Department of Medical Imaging and Clinical Oncology

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Extended 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.
Influence 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.
Response to radioiodine in male hyperthyroid patients at Tygerberg Hospital
(Stellenbosch : University of Stellenbosch, 2009-03) Onimode, Yetunde Ajoke; Ellmann, Annare; Korowlay, Nisaar; University of Stellenbosch. Faculty of Health Sciences. Dept. of Medical Imaging and Clinical Oncology. Nuclear Medicine.
ENGLISH ABSTRACT: Radioiodine therapy is reputed to yield poorer results in male patients than in females. We retrospectively reviewed the records of 308 patients treated with radioiodine-131 (RAI) for Graves’ disease (n=266, 86.4%), toxic multinodular goitres (n=35, 11.4%) and toxic solitary nodules (n=7, 2.3%). The mean age of the men was 44 ±13.6 years (range 14-77 years). Patients with GD were predominantly in the younger age groups, while those with toxic nodular goitres were in the older range. Two hundred and fifty-nine patients (84.1%) were treated with a single dose of RAI, while 49 (15.9%) required further doses. A second dose had to be administered to 38 patients, while 8 received 3 doses, 2 got 4 doses and 1 patient had 5 doses in all (these included a first dose received prior to referral to our Thyroid Clinic). Cure was determined as euthyroidism or hypothyroidism at the 3-month follow-up visit. The average pre-treatment T4 value was 68.9 ± 31.8 pmol/L (range 5.7 – 155 pmol/L); while the mean Tc-99m pertechnetate uptake value was 15.8 ± 10.9% (range 0.88 - 62.9). Patients with GD presented with more severe hyperthyroidism than the other patients; mean free T4 of 71.9 ± 31.1 pmol/L compared to 51.4 ± 29.9 pmol/L for the TMG group of patients, and 39.6 ± 26.8 pmol/L for the TSN group (ANOVA p<0.0001, confirmed by the Kruskal-Wallis test). Patients with TMG and TSN were treated with higher doses than patients with GD; mean first doses of 349.3 ± 88.5 MBq and 428.1 ± 28.6 MBq respectively, compared to a mean dose of 325.1 ± 69.3 MBq for patients with GD. Treatment with multiple doses of RAI correlated with higher values of T4 and T3 at presentation (p<0.0001). However, none of the baseline variables of age, T4 and T3, and first dose of RAI was significant predictors of free T4 outcome at 3 months. A consistently higher dose was administered to the male patients, compared to female patients of similar age, diagnosis and level of thyrotoxicosis (Tc-99m pertechnetate uptake). Despite this, male patients had similar outcomes as the female patients 3 months after therapy. Our findings lend weight to the theory that male patients are more difficult to treat than their female counterparts, seeing that the former had similar outcomes despite the significantly higher doses of RAI administered to the males.
The value of different reconstruction algorithms for quantification of FDG PET brain imaging
(Stellenbosch : Stellenbosch University, 2016-12) Moalosi, Tumelo Carel Godwin; Ellmann, Annare; Mix, Michael; Warwick, James; Du Toit, Monique; Doruyter, Alexander; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Medical Imaging. Medical Physics.
ENGLISH SUMMARY : Modern reconstruction techniques of positron emission tomography/computed tomography (PET/CT) data are optimized for whole body imaging. Such optimization is less developed for brain imaging. This study aimed at investigating the effect of different image reconstruction parameters (varying number of iterations, scan duration, relaxation parameter (smoothing levels) and the use of time of flight (TOF)) on PET/CT images with the objective of evaluating the algorithms for quantification of fluorodeoxyglucose (FDG) PET brain imaging. Materials and methods: A Philips Gemini TF Big Bore PET/CT scanner was used for acquiring the data. The study was based primarily on phantom and limited patient data for preliminary validation. Three dimensional (3D) Hoffman brain phantom (HBP) data and data of patients attending the Western Cape Academic PET/CT Centre for oncological purposes, with low probability of neurological pathology, were included in the study. The data was reconstructed using two different iterative reconstruction algorithms, row action maximum likelihood algorithm (RAMLA) and spherically symmetric basis function ordered subset algorithm (BLOB or BLOB OS), with variation in the number of iterations, scan acquisition duration, switching TOF on and off for BLOB OS and by varying the relaxation parameter. The set of output images were analyzed using MATLAB code. Results: From the HBP data, in all regions of the brain, the grey matter/white matter ratio, and the mean and the normalized mean counts increased as the number of iterations increased, reaching a plateau after 15 iterations for all algorithms. When comparing the algorithms with relaxation values λ=0.7 and λ=1.0, it was found that the latter converged faster. Overall, BLOB TOF (λ=1.0) proved to have faster convergence followed by BLOB TOF (λ=0.7). The coefficient of variation (COV) for all volumes of interest showed BLOB TOF to be superior compared to all the other algorithms. The COV results for different scan durations showed that there is minimal improvement after 5 min in high-activity regions (GM) and after 10 min in low-activity region (WM). The patient data was used as proof of principle but the numbers were too small to analyze further, as no pattern of behaviour could be identified for the different algorithms in the three patient images available. Conclusions: A higher number of iterations, such as 15, than currently used by the vendor of the PET scanner led to improved image quality for all algorithms. An acquisition time of 10 min provided an optimal trade-off between image quality and scan time irrespective of the reconstruction algorithm used. Including the TOF in the reconstruction algorithm improved the image quality, proving that TOF also improves image quality for small objects such as the brain similar to that seen for larger anatomical diameters as indicated in the literature.
Working towards the implementaion of an international accreditation programme in a Nuclear Medicine Department of a South African teaching hospital
(Stellenbosch : Stellenbosch University, 2005-04) Eiselen, Thea; Ellmann, Annare; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Medical Imaging and Clinical Oncology. Nuclear Medicine.
ENGLISH ABSTRACT: Introduction: Quality assurance in Nuclear Medicine is of utmost importance in order to ensure optimal scintigraphic results and correct patient management. A customised Quality Management System (QMS) should be documented and implemented by following the international guidelines set by the International Standardisation Organization (ISO). Materials & Methods: A Quality Control Manual (QCM), defining the departmental quality policy, mission, vision and objectives was customised following the framework of a tried and tested design. As ISO focuses on client satisfaction and staff harmony, the following departmental objectives were audited in working towards the accreditation of the Nuclear Medicine Department of Tygerberg Hospital: referring physician satisfaction, patient satisfaction as well as staff satisfaction and harmony. Information was collected by means of questionnaires completed by referring physicians and staff members. One-on-one interviews were executed on patients. An international ISO accredited Nuclear Medicine department was visited to establish the suggested path to follow en route to successful ISO accreditation and certification. Results: Referring physicians indicated overall satisfaction with service provision, but a need for electronic report and image transfers seemed too dominant. The patient satisfaction survey resulted into overall satisfaction with personal service providing, but the provision of written and understandable information, long waiting times and t equipment must receive attention. Staff questionnaires indicated a general lack of communication between different professional groups and the need for interpersonal loyalty and team building. Improvement measures were identified to ensure the continuous improvement of the QMS by focusing on these quality parameters. Conclusion: The department has QA procedures in place, but does not meet all criteria for external accreditation. In order to ensure departmental harmony and sustainability of client and staff satisfaction, the departmental objectives in measured and improved where needed. The successful implementation and continuous improvement of a customised QMS, following the guidelines outlined in the QCM will lead to successful accreditation.

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