Nuclear Medicine
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- ItemThe added value of SPECT/CT in complicated osteomyelitis(Stellenbosch : Stellenbosch University, 2013-12) Tag, Naima; Korowlay, Nisaar A.ENGLISH ABSTRACT: Background: The detection of bone infection can be very difficult especially in bone with altered structure due to prior trauma or surgical procedures. Complicated osteomyelitis (COM) is becoming a public health problem especially with the difficult choice between, high cost surgery and prolonged courses of intravenous or oral antibiotic therapy, as well as the social and psychological effect of longterm disease and disability of the patient. The correct localisation of especially bone infection is still a challenge for the clinician. The single photon emission computed tomography/low dose computed tomography (SPECT/CT), by fusing the functional information with the anatomical parts, is a wellestablished tool used in many nuclear medicine studies. This improves the overall quality of the study with more clear answers. The aim of the study was to determine the added value of SPECT/CT in the management of complicated osteomyelitis (COM) in patients with endo-prosthesis, post traumatic osteomyelitis with and without metal implants and diabetic foot. Methods: This was a prospective study, between February 2010 and February 2012. Patients with suspected COM who fulfilled the selection and inclusion criteria were included. All had abnormal three phase bone scan followed by infection imaging with 99mTc labelled white blood cells and 99mTc -colloid if the99mTc labelled white blood cell study was abnormal. 67Ga citrate was used in vertebral involvement. Planar and SPECT/CT images were reviewed for presence of abnormal uptake and for its localization in bone and soft tissue. Scan results were defined as positive or negative. Both planar and SPECT/CT images were compared regarding diagnosis and precise localization of infection. The final diagnosis was obtained from surgical specimen or microbiological culture as well as clinical follow-up of all patients. Results: There were 72 patients, 29 male and 43 female with mean age of 57 yrs [range 27-88].There were 24 patients with prosthesis, 16 with hip prosthesis (PH=16), and 8 with knee prosthesis (PK=8). There were 44 patients with post traumatic osteomyelitis, 26 with metal implants (TOM=26) and 18 without metal implants (TOWM= 18). Four patients had diabetic foot (DF= 4). Infection was diagnosed in 19/72 patients on planar images and in 21/72 on SPECT/CT. Infection was diagnosed in 4 patients with prosthesis, 16 patients with post traumatic injury and one diabetic foot patient. The four patients with prosthesis, SPECT /CT added diagnostic value by excluding osteomyelitis in 3 patients and by defining the exact extent and localizing soft tissue and bone infection (STI/OM) in one patient. In 16 patients with post traumatic OM on planar images, SPECT /CT added diagnostic value, by excluding OM in 4 patients and confirming only STI, better localisation of the uptake in bone and soft tissue in 5 patients, of them 2 patient was negative on planar, and in 7 patients, confirmed and defined the exact extent of both OM and STI. One diabetic foot was positive for STI on the planar, the SPECT/CT added diagnostic value by defining the extent of the infection. In summary the added value of SPECT/CT was: a. Overall infection: 1. Exclusion of osteomyelitis by confirming only soft tissue involvement: 7 patients (10%) 2. Better localization in bone and soft tissue: 6 patients (8%) 3. Better delineation of extent of infection: 9 patients (12%) 4. None: 50 patients (70%) b. In positive cases only: 1. Exclusion of osteomyelitis by confirming only soft tissue involvement: 7 patients (33%) 2. Better localization in bone and soft tissue: 5 patients (24%) 3. Better delineation of extent of infection: 9 patients (43%) 4. None: 0 patients The overall sensitivity, specificity, positive predictive value, negative predictive value and accuracy for infection, on planar was 90%, 100%, 100%, 97%, 97%, respectively and for SPECT/CT 100%, 100%, 100%, 100%, 100%. For OM on planar, the sensitivity, specificity , positive predictive value, negative predictive value and accuracy was 100%, 89%, 53%, 100%, 90%, respectively and for SPECT/CT 100%, 100%, 100%, 100%, 100%. Conclusion: In complicated osteomyelitis, SPECT/CT is useful in localizing, defining the exact extent of infection where the planar images are abnormal, with no added value if the planar images are negative. We recommend in clinical practice the routine use of hybrid SPECT/CT imaging in complicated osteomyelitis when planar images are abnormal.
- ItemThe added value of SPECT/CT in the evaluation of equivocal skeletal lesions in patients with known malignant disease(Stellenbosch : University of Stellenbosch, 2010-03) Ndlovu, Xolani; Warwick, James M.; University of Stellenbosch. Faculty of Health Sciences. Dept. of Medical Imaging and Clinical Oncology. Nuclear Medicine.ENGLISH SUMMARY: Introduction: Bone scintigraphy is used extensively in evaluating metastatic disease. There are currently no clear recommendations for the use of SPECT/CT in metastatic bone disease. Existing procedural guidelines from the Society of Nuclear Medicine (SNM) for SPECT/CT do not provide specific indications for use of SPECT/CT in bone scintigraphy, and there are currently no other guidelines for the use of SPECT/CT in bone scintigraphy that the author is aware of. The aim of this study was to investigate the additional value of SPECT/CT, and to identify the clinical indications for which SPECT/CT is most useful in patients with suspected bone metastases. Subjects and Methods: Forty-two patients with equivocal lesions on planar scintigraphy were prospectively recruited and planar imaging, SPECT, and SPECT/CT done on all patients. On reading of SPECT and then SPECT/CT, patients and individual lesions were classified as malignant, benign or equivocal. Radiological studies and available clinical information were also used during reading of scans. Review of clinical information, radiological studies and/or follow-up bone scans were used as gold standard. The results of the SPECT and SPECT/CT were compared in terms of proportion of equivocal findings and accuracy. Results: Forty-two patients with 189 skeletal lesions were examined. There was a diverse variety of primary tumours, although the majority had breast (n=22) or prostate cancer (n=8). Overall, SPECT/CT resulted in a significant reduction in the proportion of equivocal findings on both a patient-wise (p=0.0015) and lesion-wise basis (p<0.0001). The overall accuracy of SPECT/CT was significantly higher than that of SPECT on both a patient-wise (p=0.0026) and lesion-wise basis (p<0.0001). Generally SPECT/CT decreased the proportion of equivocal findings and increased the accuracy independent of the presence of bone pain, type of primary tumour, or skeletal region involved. SPECT/CT did not significantly improve the diagnostic confidence of readers in equivocal lumbar lesions although accuracy was significantly improved in this region. Conclusion: SPECT/CT performs significantly better than SPECT alone for the interpretation of equivocal planar lesions. There is no evidence that the benefit of SPECT/CT is dependent on the type of primary tumour or the presence of bone pain. Where resources are limited, SPECT/CT is indicated only in those patients in whom correct classification of the lesions in question is expected to alter the patient’s management. SPECT/CT images should be interpreted with the aid of a diagnostic radiologist or nuclear medicine physicians should acquire sufficient experience in Computed Tomographic image interpretation in order to optimise diagnostic benefit from SPECT/CT.
- ItemBrain SPECT in patients with neuropsychiatric SLE : the additional value of semi-quantitative analysis(Stellenbosch : University Stellenbosch, 2009-12) Khider, Mohamed Abdelrahman; Warwick, James; Whitelaw, Dave; University of Stellenbosch. Faculty of Health Sciences. Dept. of Medical Imaging and Clinical Oncology. Nuclear Medicine.ENGLISH ABSTRACT: Introduction: There is conflicting data on the value of single photon emission tomography (SPECT) for the diagnosis of neuropsychiatric SLE (NPSLE). Visual assessment of brain SPECT scans is the standard approach in clinical practice. However the definition and identification of significant changes may be limited by a high interobserver variability, especially in centres with limited experience. This may be reduced by a more objective semi-quantitative assessment. The objectives of this study were to determine the sensitivity and specificity of SPECT for the detection of NPSLE at our institution using visual assesment, to determine the additional value of using an objective semi-quantitative diagnostic criterion, and to investigate the correlation between abnormal perfusion pattern and clinical NPSLE classification in patients with active NPSLE. Material and methods: Nineteen patients with NPSLE and 19 normal controls were studied with brain SPECT. Scans were interpreted blindly by two nuclear medicine physicians using two methods; visual and semi-quantitative assessments. In the visual method, overall visual impression was recorded for each scan using a four point scale, where A=normal, B=probably normal, C=probably abnormal, and D=abnormal. In addition, each brain region was assigned a severity score from 0=normal perfusion to 3=severe hypoperfusion. In the semi-quantitative assessment, ten-band color scale was used, and perfusion deficit was quantified on the side with the lower color intensity comparing to the contralateral side. A score was given to the region with perfusion deficit according to the difference (in color bands) between the two hemispheres. Analysis was performed for the visual assessment method (overall impression and severity scores) and the semi-quantitative assessment method using a receiver operator characteristic (ROC) curve. Optimal cut-off points were determined and the accuracy of the different techniques was also compared statistically. Finally, the correlation was determined between the SPECT perfusion pattern and the clinical pattern of disease. Results: An ROC curve analysis for the overall visual impression resulted in an area under the curve of 0.76. At a cut-off point of C (probably abnormal), brain SPECT had 89% sensitivity and 57% specificity for the diagnosis of NPSLE. The severity score which include the total severity score and the modified total severity score resulted in areas under the curve of 0.75 and 0.79 respectively. The semi-quantitative assessment resulted in areas under the ROC curve of 0.80. Statistically, there was no difference between the overall visual impression, visual severity scores, and the semi-quantitative assessment. Agreement analysis between the SPECT pattern and clinical pattern of disease showed agreement in 91.6% in the diffuse pattern, whereas agreement in the focal pattern was seen in only 42.8%. Discussion and Conclusion: In this study, we found that brain SPECT is able to diagnose active NPSLE with a high sensitivity and moderate specificity. The overall visual impression, visual severity scores, and the semi-quantitative assessment showed no significant differences between the techniques. The use of the semi-quantitative assessment described may be useful in centers with limited experience in the interpretation of brain SPECT. The correlation between the SPECT pattern and clinical disease pattern may provide some insights into the pathophysiology of NPSLE.
- ItemThe effect of reconstruction algorithms (iterative versus filtered backprojection) on the diagnosis of single pulmonary nodules using Thallium-201 and Technetium-99m MIBI SPECT(Stellenbosch : Stellenbosch University, 2004-04) Ambayi, Rudo; Ghoorun, S.; Dupont, P.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Medical Imaging and Clinical Oncology. Nuclear Medicine.ENGLISH ABSTRACT: This study involved 33 patients, 19 men and 14 women. The age range was wide (20-90 years) and median age was 57 years. These patients had a single pulmonary nodule (SPN) defined radiologically as a well defined, round or oval intrapulmonary lung lesion not associated with atelectasis or adenopathy on chest radiography or computed tomography. Patients were investigated with Tc-99m MIBI and TI-201 (25 patients) and with Tc-99m MIBI alone (8 patients). Single photon emission computed tomography images were reconstructed using both iterative reconstruction (Ordered Subsets - Expectation Maximisation: aSEM) and filtered backprojection (FBP), on the Hermes system. Transverse, coronal and sagittal slices were displayed on the screen using a grey scale. The aSEM and FBP images for each study were co-registered semi-automatically using the multimodality programme on the Hermes. The best slice for the lesion was chosen according to the best view used to locate the SPN on chest radiograph. Regions of interest (Ral) were drawn manually outside the outer margin of the detected lesion, first on the aSEM image. This was automatically mirrored on the co-registered FBP image. For most patients, the background was automatically mirrored horizontally on the contralateral side, again, first on the OSEM then automatically on the FBP image. Automatic vertical mirroring or manual horizontal mirroring was used when background was found to be in a visually 'hot' area like the heart or vertebrae. The average counts and standard deviation of the Ral and background were generated automatically. Semi-quantitative image analysis was done by calculating the signal-to-noise ratio (SNR) and tumour-to-background (TIB) ratio using the following formulae: SNR = Mean counts ROI(lesion) - Mean counts background Standard deviation background TIB rati.o = -M---e-a-n-'--c-o--u-n-'t-s- ROI(lesion) Mean counts background Detection was found to be the same for the two reconstruction algorithms, that is, every lesion detected by using OSEM could also be detected by using FBP. However lesion detection did differ between Tl-201 and Tc-99m-MIBI. Sensitivity and specificity were calculated for different thresholds of SNR and TIB ratios. Receiver operating characteristics (ROC) curves were drawn to represent the different sensitivities and specificities at each threshold. Tuberculosis (TB) was not included in this analysis as uptake of Tl-20l was found to be significantly high and comparable to that of malignant nodules. However the effect of OSEM and FBP on the 'positive' TB nodules was assessed separately. By calculating the area under the ROC curves, TI-201 using OSEM was shown to be more accurate at differentiating malignant nodules from benign ones than FBP. Although this difference was not statistically significant (p=0.1 0), there was a clear tendency. The two reconstruction algorithms were found to be almost equally accurate, when using Tc-99m-MIBI, the difference between them being considerably insignificant. In conclusion, it was shown that there is a tendency that OSEM outperforms FBP for studies using Tl-201 but not for Tc-99m-MIBI.
- ItemEvaluation of BCL-2 and PARP-1 as potential therapeutic targets to radiosensitise lung cancer(Stellenbosch : Stellenbosch University, 2021-12) Guillaume, Muteba Mpolesha; Akudugu, John M.; Serafin, Antonio M.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Medical Imaging and Clinical Oncology. Nuclear Medicine.ENGLISH SUMMARY : Lung cancer remains the most incident malignancy worldwide, representing 13% of all cancers. It is also the leading cause of death in the world, accounting for 18 18.2% of global cancer-related deaths. The burden of lung cancer in Africa is increasing due to ag ageing an and population growth, increased prevalence of risks factors such as smoking, occupational exposure, infections, lifestyle changes, and environmental pollutants. The efficacy of many therapeutic strategies has been hindered by normal tissue toxicity and treatment resistance. For many cancer patients, radiotherapy has been the chosen therapeutic option to minimise cancer cell spread by shrinking the tumour while ensuring protection of normal tissue. There is evidence that small molecule inhibitor s can effectively target cell survival signa signalling pathways, but cancer cell cells manage to find molecular escape routes to either repair the damage or evade cell death. Combination therapy appears to be an appropriate approach to address these challenges. Therefore, targeting more than one component of the cell survival signa signalling pathways could potentially sensitise cancer cells to irradiation and improve the outcome of radiotherapy. The purpose of this study was to evaluate the role of targeting the anti-apoptotic (B-cell lymphoma 2 (Bcl -2)) pathway and the DNA repair (poly (ADP ADP-ribose) polymerase 1 (PARPPARP-1)) pathway with specific inhibitors in modulating the radiosensitivity of a lung cancer cell line ( and an apparently normal lung cell line ( For this, Bcl -2 and PARP PARP-1 were inhibited using ABT ABT-737 and ABT ABT-888, respectively. At a dose of 2 Gy, the typical fractional dose in conventional radiotherapy, combined inhibition of Bcl-2 and PARP-1 or inhibition of Bcl-2 alone resulted in significant radio-sensitisation in only the A549 cells. However, at a larger radiation dose of 6 Gy (a potentially useful fractional dose in hypo-fractionated radiotherapy), inhibition of Bcl-2 and PARP-1 markedly radio-sensitised the apparently normal (L132) and malignant (A549) cell lines, respectively. These findings suggest that use of Bcl-2 and PARP-1 inhibitors might be beneficial when combined with conventional radiotherapy, but not with hypo-fractionated radiotherapy when large fractional radiation doses are employed. However, validation of these results with a larger panel of cell lines is warranted.
- ItemEvaluation of small molecule inhibitors of HER2, PI3K, mTOR and Bcl-2 for their radiomodulatory effects in human breast cancer cell lines(Stellenbosch : Stellenbosch University, 2016-12) Hamunyela, Roswita Hambeleleni; Akudugu, John M.; Serafin, Antonio Mendes; Stellenbosch University. Faculty of Medicine and Health Science. Dept. of Medical Imaging and Clinical Oncology. Nuclear Medicine.ENGLISH SUMMARY : Breast cancer remains the most commonly diagnosed cancer in women. It is responsible for 32% of all cancers and 15% of all cancer-related deaths in females. Patients with triple-negative breast cancers (TNBC) constitute about one-fifth of all breast cancer patients. TNBC is an aggressive and heterogeneous disease entity in comparison with other types of breast cancer and, therefore, tends to be resistant to existing treatment regimens, such as, targeted and hormone therapies. Although cancer treatment has evolved from being invasive and highly toxic to being more specific with reduced normal tissue toxicity, intrinsic tumor resistance still limits the benefit of therapy with radiation, drugs, and antibodies. To address this important clinical challenge, attempts have been made to better understand the molecular determinants of treatment resistance. This resistance can be attributed to the heterogeneity in the distribution of potential target antigens in a given tumor cell population, which leads to the inability to effectively target all cells with toxic levels of a particular therapeutic agent. There is evidence to suggest that proliferative pathways of triple-negative tumors are still poorly understood, which could be the reason for the observed treatment resistance. Targeted treatment modalities that are singly effective for triple-negative breast cancer are lacking, partly due to paucity of relevant targets as they are devoid of the human epidermal growth factor receptor 2 (HER2), progesterone receptor (PR), and oestrogen receptor (ER). Novel treatment approaches are, therefore, needed to overcome the challenges in the treatment of triple-negative breast cancers if treatment outcomes are to be improved. Concomitant targeting of cell signaling entities other than HER2, PR and ER may sensitize triple-negative tumors to radiotherapy. In this study, inhibition of HER2, phosphoinositide 3-kinase (PI3K), mammalian target of rapamycin (mTOR), and the pro-survival gene (Bcl-2) with small molecule inhibitors, TAK-165 (against HER2), NVP-BEZ235 (against PI3K and mTOR), and ABT-263 (against Bcl-2), singly or as cocktails, resulted in significant radio sensitization of human breast cell lines with features similar to those of triple negative cancers. This radio sensitization was seen at 2 and 6 Gy, indicating that a therapeutic benefit could be derived in conventional as well as stereotactic radiotherapy. A moderate to strong synergism was also demonstrated for NVPBEZ235/TAK-165 and NVP-BEZ235/ABT-263 cocktails. The strongest synergy was seen in the latter cocktail. In conclusion, inhibition of PI3K, mTOR and Bcl-2 could potentially be effective in the treatment of triple-negative breast cancer. The therapeutic benefit can be improved, if the target inhibition is followed by radiotherapy.
- ItemEvaluation of the effect of low and intermediate frequency electromagnetic waves on radiosensitivity(Stellenbosch : Stellenbosch University, 2016-12) Chinhengo, Angela; Akudugu, John M.; Serafin, Antonio M.; Stellenbosch University. Faculty of Medicine and Health Science. Dept. of Medical Imaging and Clinical Oncology. Nuclear Medicine.ENGLISH SUMMARY : The incidence of epidemic Kaposi’s sarcoma in HIV/AIDS patients is high due to their compromised immune system. HIV-positive individuals presenting with cancer tend to be more sensitive to ionizing radiation and are at a higher risk of developing severe side effects during radiotherapy, and there is a need to develop non-invasive methods to preferentially sensitize cancer cells and reduce therapeutic doses. Here, the effects of 100 and 1000 Hz electromagnetic fields (EMF) broadcast via an argon plasma ray tube at 50 W on the radio sensitivity of apparently normal Chinese hamster lung fibroblasts (V79) and human malignant melanoma cells (MeWo) were evaluated using the colony forming assay. Pre-exposure of the fibroblasts to both fields had no effect on their radio sensitivity, if X-ray irradiation followed within 2 h or at 6 h. Significant radio sensitization was observed when X-rays were administered 4 h after EMF exposure. For the MeWo cells, pre-exposure to 100 Hz resulted in a significant radioprotection when irradiation followed within 6 h. However, treatment of these cells with a 1000 Hz field significantly potentiated the effect of X-rays. When cells were irradiated prior to EMF exposure, the V79 cells were marginally protected by the 100 Hz field and sensitized by the 1000 Hz field. In contrast, the melanoma cells were slightly protected by the 1000 Hz field and sensitized by the 100 Hz field. The survival rate of the normal fibroblasts when treated with 2 Gy, in two fractions of 1 Gy 6 h apart, was similar to those obtained when cells received an acute dose of 2 Gy 6 h prior to or after exposure to both EMF frequencies. On the other hand, the melanoma cells were significantly sensitized when they were either treated with a combination of X-rays and then 100 Hz EMF 6 h later or with a combination of either of the EMF frequencies and then X-rays 6 h later. These data suggest that use of electromagnetic fields may sensitize tumours to radiation therapy and reduce normal tissue toxicity. Informed and well-designed combinations of low-medium frequency electromagnetic fields and radiation therapy might be beneficial in the management of cancers, especially epidemic Kaposi’s sarcoma.
- ItemExtended Cr-51 RBC combined with Tc-99m RBC for the detection and localisation of occult GIT bleeding(Stellenbosch : Stellenbosch University, 2014-04) Modebe, Emmanuel Obinna; Ellmann, Annare; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Medical Imaging and Clinical Oncology, Nuclear Medicine. Radiodiagnosis.ENGLISH ABSTRACT: Background Occult blood loss from the gastrointestinal tract (GIT), causing iron deficiency often with anaemia, can be diagnostically and therapeutically challenging. This is because the endoscopic and radiologic tests may be negative due to the slow, chronic and intermittent nature of the gastrointestinal bleeding, making timing key in detection and localisation of the bleed. These limitations can be approached using two different radioactive isotopes. Firstly, we tested the sensitivity of extending Cr-51 RBC for 21 days relative to 5 days to detect GIT bleeding and its use to optimise timing of a Tc-99m RBC study for GIT blood loss localisation. Finally, we tested if the information provided by the Tc-99m RBC study aided gastroenterologic intervention for anatomical localisation of a lesion. Method In this retrospective review, after obtaining institutional and ethics committee approval, records of patients referred for evaluation of possible GIT blood loss were reviewed. In each; daily appearance of radiochromium in stool was measured in the whole body counter. In those cases exceeding 50 ml/day, a technetium-99m (Tc-99m) localization study was performed. These studies were correlated with clinical findings. Results A total of 59 Cr-51 RBC studies were carried out in 36 females and 21 males (n = 57). In 32 (54%) the radiochromium results were positive with 75% of the bleeding incidences occurring after 5 days of stool collection. Of 17 cases in whom Tc-99m RBC imaging studies were performed, 14 (82%) were positive with specific anatomical sites successfully defined in twelve. In all patients with blood loss of >100 ml/24h, Tc-99m RBC were positive and localised. Ten of the 17 Tc-99m RBC studies were further investigated and half diagnosed with small-bowel angiodysplasia. Conclusion This sequential twin isotope method is practical in revealing otherwise silent intestinal haemorrhage. Although it has good patient acceptability and clinical as well as diagnostic utility in management, further studies are required to clearly establish a cut-off level of blood loss for performing imaging studies and the impact of the findings on the overall patient management.
- ItemGlomerular filtration rate measurement and estimation : improvement and validation of existing methods(Stellenbosch : Stellenbosch University, 2019-12) Holness, Jennifer Lyn; Warwick, James Mathew; Davids, Mogamat Razeen; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Medical Imaging and Clinical Oncology. Nuclear Medicine.ENGLISH SUMMARY : Glomerular filtration rate (GFR) is regarded as the best measure of kidney function. It can either be measured or estimated. This dissertation aims to provide a better understanding of GFR measurement in order to improve its performance and interpretation. It also aims to validate GFR estimation in local populations and to demonstrate the utility of simple adaptations of existing equations to improve estimation. On completion of a GFR measurement, various quality control (QC) checks are performed to ensure the accuracy of the result. However, this requires comparison with clearly defined reference ranges. In a study of healthy, potential kidney donors, reference data for two QC parameters were defined. In a study analysing the effect of measurement errors on GFR, the single-sample method was found to be the most robust technique overall, although for all methods measurement error was generally insignificant compared to expected biological variation in GFR. However, at low GFR values measurement errors were shown to affect all methods significantly. Errors in measurement of the doses were found to have the greatest impact on accuracy. Using nuclear medicine techniques 51Cr-ethylenediaminetetra-acetic acid (51Cr-EDTA) is the most commonly used and widely studied exogenous filtration marker. However, 99mTc-diethylenetriaminepenta-acetic acid (99mTc-DTPA) is gaining favour because of a few technical advantages it has over 51Cr-EDTA, its lower cost, and recent issues with the availability of 51Cr-EDTA. In response to a systematic review suggesting that GFR measurement from the plasma clearance of 99mTc-DTPA was inaccurate, a mini meta-analysis was performed that demonstrated excellent agreement between 51Cr-EDTA and 99mTc-DTPA clearance, thus supporting the use of 99mTc-DTPA as a reliable alternative. Where GFR cannot be routinely measured, it is frequently estimated using a creatinine-based equation. The use of any equation first requires validation in the population in which it will be used. In a study evaluating the Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations in non-cancer, mixed ancestry adults, both equations were found to perform well. However, in a study that evaluated equations in adults with cancer, the GFR estimates were found to be biased and imprecise. This study highlighted the limitations of using estimated GFR for guiding management decisions in cancer patients. A further study evaluated 11 estimating equations in non-cancer and cancer populations of South African children. The accuracy of all estimates was poor, particularly in the cancer group. Given the extensive use of GFR estimates in South Africa, these findings have profound implications for their use in the management of children and adults with cancer in this country. Developing new equations for a specific population requires large datasets and incurs costs that are impractical in most middle- or low-income countries. A simpler alternative is to adapt existing equations. This work demonstrates the application of a relatively simple approach to adapt existing equations, using modest amounts of data and a readily available Microsoft® Excel-based tool. While this approach is simple and likely to require further refinement, its utility was demonstrated in paediatric and adult cancer populations.
- ItemHow efficient is Technitium -99m labelling of erythrocytes in patients with malaria?(2011) Ekoume, F. P.; Rubow, S. M.ENGLISH ABSTRACT: With the expansion of Nuclear Medicine techniques in developing countries, it is essential to ensure a quality imaging procedure. In the case of red cell labelling, any factor which interferes with the labelling can lead to sub-optimal studies. With regard to the high incidence of malaria in sub-Saharan African countries in general and in Cameroon particularly, a high percentage of patients referred to Nuclear Medicine departments also have malaria. The question arose whether the presence of Plasmodium in erythrocytes or anti-malarial medication could affect the labelling of erythrocytes with technetium-99m. The aim of this study was to investigate the impact of Plasmodium and anti-malarial medication on Tc-99m red cell labelling efficiency with in vitro kits in a population with a high prevalence of malaria infection. Approval for this study was obtained from ethics committees of both institutions. Three groups of 30 patients were enrolled in the study after giving informed consent: 1. Smear-negative patients in an area where malaria is endemic (control group M-). 2. Patients with malaria as determined by a positive malaria smear test (group M+). 3. Patients with malaria and on anti- malaria medication (group Mm). From each patient, a 5 ml blood sample was drawn in a heparinised blood collection tube. The red blood cells of each sample were labelled in vitro with Tc-99m, using an in vitro red blood cell kit. Labelling efficiency of the 3 groups was compared. The average labelling efficiency was 98.2% ± 2.3% in malaria-free individuals, 98.6% ± 2.6% in patients with malaria but not on treatment, and 98.6% ± 1.1% in patients with proven malaria on quinine treatment. Non parametric data analysis using the Kruskal-Wallis ANOVA test for the percentage of labelling efficiencies showed a P-value of 0.2117 which was a confirmation that there was no significant difference between the labelling efficiencies for the three groups. Radioactively labelled red blood cells are used in various nuclear medicine studies. Various drug therapies, including antibiotics, are known to either inflict direct or indirect damage to RBCs or their precursors or to impact influx or efflux of Tc-99m-pertechnetate into or out of RBCs, thereby decreasing labelling efficiency to such an extent that poor and inaccurate diagnostic information is obtained. The results of this study indicate that malaria parasites and anti-malarial treatment with quinine do not affect in vitro erythrocyte labelling with Tc-99m, and should thus not interfere with nuclear medicine investigations.
- ItemImaging of renal hyperparathyroidism using SPECT/CT with low-dose localizing CT(Stellenbosch : Stellenbosch University, 2013-12) Doruyter, Alexander Govert George; Warwick, James Matthew; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Medical Imaging and Clinical Oncology. Division of Nuclear Medicine.ENGLISH ABSTRACT: Background: Hybrid imaging using single photon emission computed tomography/low dose (x-ray) computed tomography (SPECT/LDCT) is of benefit in preoperative scintigraphy of primary hyperparathyroidism. The role of SPECT/LDCT in preoperative assessment of renal hyperparathyroidism has not yet been examined. The aim of the study was to determine whether SPECT/LDCT conferred any benefit over SPECT alone in terms of detection and/or localization of hyperfunctioning parathyroid tissue in this patient group. Methods: A retrospective study of patients with renal hyperparathyroidism and positive planar and SPECT scintigraphy was undertaken. All patients underwent planar scintigraphy using 99mTc-pertechnetate immediately followed by 99mTc-sestamibi as well as SPECT/LDCT 60 min after sestamibi injection and a delayed static image to assess for differential washout at 2-3 hours. Planar subtraction images were generated. For each patient, two nuclear physicians reported on planar+ SPECT images followed by planar + SPECT/LDCT images (assisted by a radiologist). Confidence for the presence of hyperfunctioning parathyroid tissue as well as confidence of location was scored on a Likert-type scale. Interpretation of planar + SPECT was compared with interpretation of planar + SPECT/LDCT. The impact of LDCT on equivocal lesions and number of ectopic lesions detected was also assessed. Results: Twenty patients (M:13; F:7) imaged between February 2008 and June 2011 were included [mean age: 40 years (24 – 55)]. Mean creatinine was 687 μmol/l (169-1213), mean corrected calcium: 2.55 mmol/l (1.95-3.33) and median PTH 167 pmol/l (2.4 - >201). Thirty-five lesions were detected on planar and SPECT and this was unchanged after assessment of the LDCT data. Confidence for the presence of parathyroid pathology changed in 5 patients (5 lesions) with the addition of LDCT. LDCT changed the mean confidence of parathyroid pathology from 3.17 to 3.29 (p=0.16). Addition of LDCT reduced the number of equivocal lesions from 18 (14 patients) to 14 (10 patients) (p=0.13). The addition of LDCT changed localization in 4 lesions (3 patients). Confidence in localization of pathology changed in 9 lesions (7 patients) and the mean localization confidence score was improved from 4.2 to 4.46 (p=0.002) with LDCT. The number of lesions classified as ectopic increased from 5 (on planar+SPECT) to 8 (with addition of LDCT) (p=0.25). Conclusion: In renal hyperparathyroidism SPECT/LDCT altered localization of lesions detected on planar and SPECT alone and improved reader confidence of localization accuracy. SPECT/LDCT conferred no additional benefit over SPECT in terms of detection, confidence of parathyroid pathology or ability to distinguish equivocal from non-equivocal parathyroid lesions. The addition of LDCT did not detect significantly more ectopic lesions. Whereas the minor improvement in reader confidence of localization (with addition of LDCT) was of questionable clinical significance, we speculate that the changed and presumably improved localization of lesions on SPECT/LDCT had potential clinical impact in a significant proportion of patients. On this basis we recommend the use of hybrid SPECT/LDCT in imaging of renal hyperparathyroidism when surgery is considered.
- ItemImplementation of guidelines on hospital radiopharmacy in low-income settings(Stellenbosch : Stellenbosch University, 2020-12) Ekoume, Fany Pricile; Rubow, Sietske Margarete; Boersma, Hendrikus H.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Medical Imaging and Clinical Oncology. Nuclear Medicine.ENGLISH SUMMARY : Although radiopharmacy is more than 50 years old, it is still in a stage of rapid development. This dissertation focuses on quality issues in radiopharmacies in developing countries. Guidelines for radiopharmacy practice in many countries prescribe complex facilities, especially air handling units, and extensive quality assurance and documentation requirements. In developing countries, these guidelines are currently not always met. In numerous countries in Africa, enforcement of the international guidelines would lead to closure of radiopharmacies, and consequently, loss of Nuclear Medicine services. The question arises what the consequences of not meeting the requirements of the guidelines are, and if practice can be improved without major expenditure. This study considered certain aspects of Good Radiopharmacy Practice (GRP) recommendations and collected information from both a relatively well-equipped facility at Tygerberg Hospital (TBH) in South Africa, and a more basic radiopharmacy facility at Yaoundé General Hospital in Cameroon (YGH) to investigate the conditions that will ensure safe and effective products. Factors assessed include efficacy and microbial safety of the radiopharmaceuticals, with some comparison to a state-of-the-art Good Manufacturing Practice (GMP) compliant radiopharmacy at the University Medical Centre Groningen (UMCG) in the Netherlands. An adapted version of the Quality Management Audits in Nuclear Medicine (QUANUM) tool, tailored for the radiopharmacy context, was used to determine the status of practice in the two African radiopharmacies. Once the current situation and product quality in these radiopharmacies was determined, basic, low-cost interventions to minimise deficiencies were implemented at YGH and the effects of the interventions were assessed. Where the necessary level of safety and efficacy could not be met with currently available systems despite interventions, this was reported. The efficacy of radiopharmaceuticals depends on their radiochemical purity. As lack of validation of analytical methods was one of the shortcomings noted in the YGH audit, experimentally validating a cost-effective radiochromatography method to be used at YGH was the first step of corrective actions implemented. As the provision of clean air and maintenance of air handling systems and equipment require a large budget, special emphasis was placed in three further chapters of the dissertation on assessment of microbial contamination of products, and measures to ensure sterility of products. At YGH, we reached better control of microbiological air quality. This was achieved by the implementation of simple microbiological air sampling methods, and subsequent introduction of hygienic and procedural improvements. Sterility testing of SPECT radiopharmaceuticals showed a low contamination rate at both TBH and YGH. Nevertheless, preparing radiopharmaceuticals in a well-maintained laminar air flow cabinet is recommended in order to reduce the risk of contamination of products by airborne microorganisms. The serious consequences that could arise from not meeting GRP requirements, include transmission of microbial infection to patients or administering radiochemically impure products. This dissertation presents the first work evaluating an affordable approach of the implementation of GRP in sub-Saharan Africa. It is highly recommended to all radiopharmacies in the developing world to adapt GRP in their context and to implement an optimised quality assurance programme, striving for continuous improvement.
- ItemInfluence of acquisition time and smoothing parameters on Ga-68 wholebody PET/CT image quality(Stellenbosch : Stellenbosch University, 2020-12) Diale, Boitshoko Phenyo; Moalosi, Tumelo C. G.; Mix, Michael; Ellmann, Annare; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Medical Imaging and Clinical Oncology. Nuclear Medicine.ENGLISH SUMMARY : PET/CT image optimization has been extensively investigated for 18F–FDG PET imaging. Although 68Ga–tracers are already widely used in PET, optimized imaging and reconstruction are still missing. The aim of this research was to optimize image quality for 68Ga scans under the constraint that the administered dose to a patient and acquisition time are limited. Materials and Methods : A Gemini TF Big Bore PET/CT system manufactured by Philips was used to acquire the images. The experimental data was formulated by retrospectively collecting data from patient scans, who had undergone wholebody (WB) PET/CT using 68Ga–DOTANOC for oncological imaging. The patient data sets were analyzed for this study to plan phantom measurements which simulated a typical activity distribution like in the patient scans. The NEMA (IEC) body phantom filled with low contrast and high contrast activity ratios was scanned on the Gemini TF Big Bore PET/CT scanner using the patient acquisition protocol. The data was reconstructed using a default WB reconstruction protocol with different smoothing parameters and varying scan acquisition times for low and high contrast data. Additionally a HN protocol with smaller voxel sizes was also used on high contrast data. The set images were analyzed using R Studio. Image quality parameters such as coefficient of variation (COV%), contrast to noise ratio (CNR), signal to noise ratio (SNR), recovery coefficient (RC%) and uniformity in terms of standardized uptake value (SUV) were acquired. Results: For low contrast COV%, CNR, SNR values varied as follows: 0.89 – 0.99%, 0.96 – 1.08, 0.99 – 1.05, respectively. Values for high contrast varied as follows: 1.03 – 1.16%, 0.84 – 0.91, 0.80 – 0.97. When comparing COV%, CNR and SNR, low contrast images appeared to be superior to high contrast images. The RC% was found to be consistent in both low contrast and high contrast irrespective of the smoothing parameter. Conclusion: The results obtained from the phantom study demonstrated the Philips Gemini TF Big Bore PET scanner’s stability of good uniformity when assessing maximum activity concentration among the different acquisitions, and ability of the scanner to detect or recover radioactivity in low and high contrast images for all reconstruction parameters. From the phantom study results, incorporating the smoothing reconstruction parameter ”smooth” on low contrast images, allowed the reduction of acquisition time to 180 seconds while maintaining acceptable image quality.
- ItemInvestigation into various aspects of radiolabelling somatostatin peptide derivatives with 68Ga eluted from a SnO2-based 68Ge/68Ga generator(Stellenbosch : Stellenbosch University, 2018-03) Prince, Deidre Mabel; Rubow, Sietske Margarete; Rossouw, Daniel Dutoit; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Medical Imaging and Clinical Oncology. Nuclear Medicine.ENGLISH SUMMARY : 68Ge/68Ga generators ensure the supply of 68Ga for positron emission tomography (PET), for instance for somatostatin receptor imaging with 68Ga-DOTA-labelled somatostatin analogues. There are various generators available and their eluates are processed differently for radiolabelling of peptides. The objectives of this study were to investigate various aspects of the elution characteristics of the generator, to optimize labelling conditions using different eluate processing techniques such as fractionation and cation exchange chromatography and to develop user-friendly kit formulations. This study was approved by the Stellenbosch University Health Research Ethics Committee and permission was granted for the experimental work to be conducted at iThemba LABS. Elution efficiencies were determined using different HCl concentrations (0.2 M – 1.0 M). Metal analysis and 68Ge breakthrough determination were performed on eluates. Radiolabelling parameters were optimized, using fractionated eluates and different DOTA-peptide masses (15 to 50 μg) at pH 3.5 – 4.0 in sodium acetate buffer. Different heating times and heating methods and the influence of various periods of non-elution of the generator on radiolabelling results were investigated. Cationic resins were investigated for eluate processing. Radiolabelling parameters, using cationic resin-processed eluates, were optimized. Labelling was conducted at various pH values, using different quantities of buffer. DOTA-peptide kits for both fractionated and resin-processed eluates were developed and tested for sterility, endotoxin content and stability. Radiochemical yields, radiolabelling efficiency and radiochemical purity of 68Ga-DOTA-peptides were determined. The elution efficiency of the generator increased with an increase in the concentration of HCl eluent. The 68Ge breakthrough increased dramatically at 0.8 M HCl. Most metal contaminants were lowest when eluting with 0.2 M HCl and the Zn content increased with the increase in HCl concentration. The eluent of choice for the SnO2-based generator was confirmed to be 0.6 M HCl. For radiolabelling, 35 μg DOTA-peptide (9.2 – 9.4 μM) was the most favourable. Extended heating times and heating method did not significantly impact on the radiolabelling. The radiolabelling efficiencies were consistently above 90 % even after 3 weeks of non-elution of the generator, but radiochemical yields dropped after 7 days. DOTA-peptide kits for fractionated eluates were successfully developed and the radiolabelling quality was found to be superior over peptide stock solutions. A radiolabelling method using a cationic exchange resin was successfully adapted for the SnO2 generator. 68Ga was efficiently adsorbed on a Bond Elut SCX (100 mg) cartridge and desorbed by acidified solutions of NaCl. The SCX resin effectively removed about 98 % of deliberately “spiked” metals from the 68Ga eluate. An optimized labelling method based on the use of SCX-purified eluates was developed, producing radiochemical yields of almost 85 % and lead to the successful formulation of DOTATATE kits. The quality was found to be suitable over a 3-month period. In conclusion, a kit type labelling procedure, using cationic resin purified 68Ga eluates, provides the most practical method to produce 68Ga-labelled DOTA-peptides.
- ItemAn investigation of the contribution of Single Photon Emission Computed Tomography to the diagnosis of skeletal metastases using bone scan in the African context(Stellenbosch : Stellenbosch University, 2003-12) Elmadani, Ahmed Elkhidir; Warwick, James M.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Nuclear Medicine.ENGLISH ABSTRACT: Planar bone scintigraphy is highly sensitive but it may not be sensitive enough to detect subtle lesions in complex bony structures such as the spine. The accurate anatomic localisation of lesions in regions such as this is also limited using planar images. Single Photon Emission Computed Tomography (SPECT) results in a higher lesion contrast resulting in an improved sensitivity for the detection of subtle lesions. SPECT also enables improved lesion localisation, often valuable in distinguishing benign from malignant disease in the spine. A number of previous studies have demonstrated that the addition of SPECT of the spine significantly enhances the value of bone scintigraphy for the detection of bone metastases compared to planar imaging alone. These studies were however not done in the African context where patients typically present with more advanced disease. In a retrospective study of 576 patients with known primary tumors sent to our institution for bone scintigraphy for the diagnosis of bone metastases, we evaluated 119 patients in whom both planar imaging and SPECT were obtained. The studies were graded for the probability of metastatic disease, and the number of spinal lesions was determined with and without SPECT. The influence of adding SPECT on the interpretation of the study was determined in terms of the reported probability of metastatic disease, the exclusion and confirmation of metastatic disease, the decisiveness of interpretation, and the number of spinal lesions. The addition of SPEeT resulted in a statistically significant change in the interpretation of studies, although the actual numbers of patients affected were relatively small. SPEeT resulted in a more decisive interpretation of bone scintigraphy. There was a significant increase in the number of spinal lesions detected after the addition of SPEeT. It was concluded that although the use of SPEeT is ideal, acceptable results could be achieved using planar imaging alone in this patient population. This is particularly relevant in the African context, where SPEeT is often unavailable or scarce and in great demand.
- ItemMonitoring various eluate characteristics of the iThemba LABS SnO2-based 68Ge/68Ga generator over time and validation of quality control methods for the radiochemical purity assessment of 68Ga-labelled DOTA peptide formulations(Stellenbosch : Stellenbosch University, 2017-03) Davids, Claudia Ruby; Rubow, Sietske Margarete; Rossouw, Daniel; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Medical Imaging and Clinical Oncology. Nuclear MedicineENGLISH SUMMARY : PET imaging with gallium-68 (68Ga) has become widely used due to the availability of 68Ge/68Ga generators and DOTA-derivatised peptide ligands for radiolabelling. The purpose of this study was to monitor the eluate of two iThemba LABS 68Ge/68Ga generators over a period of 12 months to ascertain whether all quality parameters of the 68Ga eluate remained stable and to validate different analytical methods used to determine the radiochemical purity of 68Ga-labelled peptides. Two 1850 MBq (50 mCi) generators were eluted daily with 0.6 M HCl and metal contaminants, 68Ge breakthrough, 68Ga yield, pH, sterility and endotoxin concentrations were determined on a monthly basis. The radiochemical purity of 68Ga-labelled peptides was ascertained using high performance liquid chromatography (HPLC) and instant thin layer chromatography (iTLC). iTLC experiments were performed using both dried and undried iTLC plates. iTLC was also carried out on labelled peptide solution that was spiked with 68GaCl3. These results were also compared with those using HPLC. After 12 months the 68Ga yields, total metal contaminants, sterility and endotoxin concentration remained within European Pharmacopoeial limits. The 68Ge breakthrough increased as the generator aged. This can however be minimised by fractionated elution and post-labelling processing of the eluate by anion or cation exchange chromatography. Separation between 68GaCl3 and 68Ga-labelled peptides was obtained using both 0.1 M citrate buffer pH 5.0 (mobile phase 1) and 1 M ammonium acetate : methanol (1:1) (mobile phase 2). The results also showed that the distribution of radioactivity on the iTLC strip could be determined using a dose calibrator when a TLC scanner is not available. Experiments performed using both undried and dried iTLC-SG chromatography paper, demonstrated that despite the statistically significant difference between the sets of results, in practice either undried or dried iTLC may be used. When purified 68Ga-labelled peptides were spiked with 2% of 68GaCl3, separation between the two was obtained on both HPLC and iTLC. However, iTLC underestimated and HPLC overestimated 68GaCl3 content. Of the two iTLC methods investigated, the method using mobile phase 2 was able to separate colloidal 68Ga impurities from the 68Ga-labelled peptides while the method using mobile phase 1 and the HPLC method could not. In conclusion, the iThemba LABS 68Ge/68Ga generator can be considered stable and of use for up to one year after its manufacture. Both the iTLC method and the HPLC method could detect 68GaCl3 amounts less than 2%. The pharmacopoeia states that 68Ga must be less than 3 % on iTLC and less than 2 % on HPLC. Either dried or undried iTLC strips can be used and if a radio-TLC scanner is not available, the iTLC strips developed with mobile phase 1 can be cut at a suitable distance from the origin and the activity on each section can be read in a dose calibrator. iTLC chromatography using ammonium acetate/methanol seems to be the optimal system for routine analysis of 68Ga labelled DOTA-peptides, as it separates both 68GaCl3 and colloidal impurities from the labelled peptides and is a fast and easy technique.
- ItemOptimal utilization of gamma camera time in Tc-99m MDP bone scintigraphy(Stellenbosch : University of Stellenbosch, 2007-03) Jawa, Zabah Muhammad; Rubow, Sietske; Warwick, James; University of Stellenbosch. Faculty of Health Sciences. Dept. of Medical Imaging and Clinical Oncology. Nuclear Medicine.Introduction: Whole body bone scintigraphy with Tc-99m MDP is able to provide a survey of the entire skeleton. The question arises if it is mandatory to perform a whole body bone scan in all patients, irrespective of the clinical indication. The aim of this study is to determine the implications of performing limited imaging in patients who had whole body bone scan for various clinical patholgy with Tc-99m MDP, in order to determine if limited imaging would be acceptable in selected pathologies. This may enable gamma camera time to be optimally utilized in units with limited facilities. Materials and Methods: Reports of 3015 patients with various clinical pathologies who had whole body bone scans with Tc-99m MDP in our department from January 2002 to December 2004 were retrospectively reviewed. The presence of pathologic radiotracer uptake was analyzed in order to establish the pattern of distribution. Clinically significant skeletal lesions were classified according to the anatomical regions where they were located viz; skull (including the neck), axial skeleton (including the pelvis and shoulders) and limbs. Results: Our results showed that in patients with lung cancer, soft tissue sarcoma, and myeloma, there was an error in more than 25% of patients when limited imaging was performed. In patients with cancer of the breast, prostate, kidney, gastrointestinal system, and reproductive system and lymphoma there is an error in less than 5% of patients when limited imaging is employed. For iv patients with more localized musculoskeletal disorders such as suspected stress fractures, complicated joint prosthesis and avascular necrosis of the femur head, regional imaging of the area of pathology showed a percentage error of less than 6%.
- ItemOptimization of production methods for gallium-68 PET radiopharmaceuticals in a hospital radiopharmacy(Stellenbosch : Stellenbosch University, 2020-12) Le Roux, Johannes Stephanus; Rubow, Sietske MargareteENGLISH SUMMARY : Production of radiopharmaceuticals intended for human use and research purposes is generally performed in well-equipped commercial or research facilities that usually have access to advanced equipment for the synthesis and quality control of radiopharmaceuticals. Nuclear Medicine departments are in most cases situated in hospitals. Radiopharmacies in these departments usually have limited space and equipment which necessitates careful consideration of suitable production methods. Optimization may include methods to simplify quality control procedures through the use of less sophisticated equipment and procedures. The purpose of this study was to demonstrate how to optimize production methods in an environment with limited resources using ubiquicidin labelled with gallium-68 as an example. The peptide ubiquicidin is currently investigated for localization of infections in patients using positron emission tomography (PET). Until recently, labelling ubiquicidin with gallium-68 was limited to a manual labelling method. Manual labelling methods are not recommended for the routine production of radiopharmaceuticals because of difficulty to comply with Good Manufacturing Practice (GMP). Manual labelling methods can also result in high radiation exposure to personnel. These disadvantages can be addressed by automation of production methods. The research conducted in this study shortly entails the following aspects: •Automation of a manual labelling method of ubiquicidin with gallium-68 •Optimization of the synthesis methods using radical scavengers •In-depth comparison of the labelling characteristics of the manual method to that of theautomated methods •Conducting a literature search into the toxicity of HEPES in humans and animals in order toclarify its use as a buffering agent in the labelling of radiopharmaceuticals • Investigating thin-layer chromatography as method to determine the radiochemical purity of gallium-68 ubiquicidin Two different automated synthesis methods were developed in this study. Optimization of the labelling methods was achieved by adding free-radical scavengers to reduce the formation of impurities. A comparison of the labelling characteristics of the manual labelling method with the automated methods showed that the results obtained with automated methods were more robust and repeatable. The literature search into the toxicity of HEPES showed that its toxicity in humans and animals may be overestimated by pharmacopoeias. The current limits applied by pharmacopoeias may be too strict. An evaluation of several thin-layer chromatography methods indicated that the method currently described in the literature may underestimate the presence of colloidal impurities in the final product. None of the other methods investigated in this study could distinguish the colloidal impurity from the labelled product. This aspect highlights the need for a final purification step to reduce the presence of colloidal impurities in the final product. The work presented in this study creates an important basis for optimization of production methods in a clinical environment. The study can further serve as a guideline to other nuclear medicine departments for optimization of radiopharmaceutical production methods.
- ItemPulmonary embolism diagnosis : a clinical comparison between conventional planar and SPECT V/Q imaging using Krypton 81m – with CTPA as the gold standard(Stellenbosch : University of Stellenbosch, 2010-03) Ngoya, Patrick Sitati; Korowlay, Nisaar A.; University of Stellenbosch. Faculty of Health Sciences. Dept. of Medical Imaging and Clinical Oncology. Nuclear Medicine.ENGLISH ABSTRACT: Single photon emission computed tomography (SPECT) with a superior contrast resolution has been shown to be more sensitive and specific with a lower nondiagnostic rate than planar imaging in many nuclear medicine studies but it is still not being routinely implemented in V/Q studies at many centres including Tygerberg Hospital. There are many studies on V/Q SPECT using Technegas as a ventilation agent but very limited studies available on 81m Kr gas. Aim: To clinically compare conventional planar and SPECT V/Q imaging using 81mKr gas in the diagnosis of pulmonary embolism, with CTPA as the gold standard. Patients and Methods: All patients referred with clinical suspicion of pulmonary embolism were assessed. The inclusion criteria were normal chest radiograph, normal renal function and no contrast allergy. Exclusion criteria were age below 18 years old, pregnancy, abnormal chest radiograph, abnormal serum creatinine/urea levels and unstable patients. A Well’s score was assigned to each enrolled patient. Perfusion scintigraphy was performed after intravenous injection 125 MBq of 99mTc MAA. Ventilation scintigraphy was performed with 81mKr gas. On a dual head camera, SPECT was done before planar acquisition, while perfusion was done before ventilation imaging in the same position. Planar V/Q images consisted of 6 standard views. All V/Q SPECT images were reconstructed using ordered-subset expectation-maximization (OSEM) algorithm and a post-reconstruction 3D Butterworth filters were applied. V/Q Planar and V/Q SPECT images were later evaluated and reviewed separately and reported based on recent EANM guidelines blinded to the CTPA results. All patients underwent multi-slice CTPA examinations on a 40-detector row scanner. The images were later assessed and reported blinded to the V/Q results. Statistical analysis was done using the Fisher exact test for comparison of categorical variables and the one-way ANOVA for continuous variables (p<0.05 was significant). Results: A total of 104 consecutive patients were referred with clinical suspicion of pulmonary embolism. Seventy-nine patients were excluded from this study mostly due to abnormal serum creatinine/urea levels. Only 25 patients were included in this study, with a mean age of 48 ± 19 years, and 64% being females. When compared to CTPA as gold standard, the prevalence of PE was 16% [5% – 37% at 95% CI], sensitivity 75% [21% – 99% at 95% CI], specificity 90% [68% – 98% at 95% CI], positive predictive value 60% [17% – 93% at 95% CI], negative predictive value 95% [73% – 100% at 95% CI] and diagnostic accuracy 88% [69% – 97%at 95% CI] for both V/Q Planar and SPECT. V/Q Planar showed a lower reader confidence i.e. could only clearly resolve 72% of cases compared to V/Q SPECT, which could precisely interpret all cases, showed more and better delineated mismatch vs match and segmental vs non-segmental defects. All patients who were scored as PE unlikely on Wells’ score (4) had PE ruled out on CTPA (p=0.04581) as well as 89% of patients on V/Q SPECT and V/Q Planar. Conclusion: Based on this study, V/Q Planar and V/Q SPECT have a similar diagnostic performance in patients with a normal or near normal chest X-rays.
- ItemRadiosensitisation of low HER-2 expressing human breast cancer cell lines(Stellenbosch : Stellenbosch University, 2015-04) Hamid, Mogammad Baahith; Akudugu, John M.; Serafin, Antonio M.; Stellenbosch University. Faculty of Health Sciences. Dept. of Medical Imaging and Clinical Oncology. Nuclear Medicine.ENGLISH ABSTRACT: Breast Cancer remains one of the world’s leading causes of cancer related deaths amongst women. Its treatment has evolved from invasive, highly toxic therapies to treatments that possess a higher specificity and a lower toxicity. Despite improvements in overall survival, many patients do not benefit from these agents because of acquired and/or inherent tumour resistance, which could hinder treatment efficacy. Novel treatment strategies are, therefore, warranted to address these challenges and to significantly improve patient responses. Inhibiting components of the HER-2 signalling pathway can significantly sensitise breast cancer cells to low doses of ionising radiation. The objective of this study was to inhibit key molecular targets of the human epidermal growth factor receptor 2 (HER-2) signalling pathway and expose breast cancer cell lines to doses of radiation, so as to establish potential therapeutic targets that may be amenable to combined modality therapy, and formulate a cocktail of inhibitors to evaluate its radiosensitising capability. This study found that pre-treatment of two breast cancer cell lines (MDA-MB-231 and MCF-7) with a HER-2 inhibitor (TAK-165) had little or no effect on radiosensitivity. However, a radiation enhancement was observed when these cells were pre-treated either with BEZ235, a dual inhibitor of phosphoinositide 3-kinase (PI3K) and mammalian target for rapamycin (mTOR), or a cocktail of TAK-165 and BEZ235. These findings suggest that concurrent inhibition of HER-2, PI3K and mTOR during radiotherapy might improve treatment response of breast cancer patients.