Asia Oceania Journal of Nuclear Medicine & Biology
Volume:4 Issue: 1, Winter 2016

AOJNMB is striving for excellence. Our journal is publishing its 4th volume of publication and we are delighted to observe on time publication of this journal with important scientific articles. On November 2015, 11th Asia Oceania Congress of Nuclear Medicine & Biology (AOCNMB) was held in Jeju International Convention Center (JICC) in Korea with hundreds of participants and the abstracts of the meeting were published as a supplement issue of the AOJNMB (1). The 11th AOCNMB meeting was a great opportunity for me to thank the best contributors of the AOJNMB in the last three years. Actually, AOJNMB awarded three contributors for their invaluable effort in years 2013-2015. Prof. Seigo Kinuya was awarded as our “Best Associate Editor” for the highest number of successful editorship, Prof.Henry Bom as “Top Contributor” with the highest number of reviewed articles and Prof.Jerry Obaldo as the “Best Reviewer” for his rapid, critical and instructive reviews.

The mortality of patients with locally advanced triple-negative breast cancer (TNBC) is high, and pathological complete response (pCR) to neoadjuvant chemotherapy (NAC) is associated with improved prognosis. This retrospective study was designed and powered to investigate the ability of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) to predict pathological response to NAC and prognosis after NAC. The data of 32 consecutive women with clinical stage II or III TNBC from January 2006 to December 2013 in our institution who underwent FDG-PET/CT at baseline and after NAC were retrospectively analyzed. The maximum standardized uptake value (SUVmax) in the primary tumor at each examination and the change in SUVmax (ΔSUVmax) between the two scans were measured. Correlations between PET parameters and pathological response, and correlations between PET parameters and disease-free survival (DFS) were examined. At the completion of NAC, surgery showed pCR in 7 patients, while 25 had residual tumor, so-called non-pCR. Median follow-up was 39.0 months. Of the non-pCR patients, 9 relapsed at 3 years. Of all assessed clinical, biological, and PET parameters, N-stage, clinical stage, and ΔSUVmax were predictors of pathological response (p=0.0288, 0.0068, 0.0068; Fischer’s exact test). The cut-off value of ΔSUVmax to differentiate pCR evaluated by the receiver operating characteristic (ROC) curve analysis was 81.3%. Three-year disease-free survival (DFS) was lower in patients with non-pCR than in patients with pCR (p=0.328, log-rank test). The cut-off value of ΔSUVmax to differentiate 3-year DFS evaluated by the ROC analysis was 15.9%. In all cases, 3-year DFS was lower in patients with ΔSUVmax <15.9% than in patients with ΔSUVmax ≥15.9% (p=0.0078, log-rank test). In non-pCR patients, 3-year DFS was lower in patients with ΔSUVmax <15.9% than in patients with ΔSUVmax ≥15.9% (p=0.0238, log-rank test). FDG-PET/CT at baseline and after NAC could predict pathological response to NAC before surgery and the clinical outcome after surgery in locally advanced TNBC patients.

In clinical practice, approximately 10-25% of post-surgical differentiated thyroid carcinoma (DTC) patients with high serum thyroglobulin (Tg) and negative 131I whole-body scan (WBS) have poor prognosis due to recurrent or metastatic lesions after radioactive iodine treatment. The purpose of this study was to evaluate the value of 18F-FDG PET/CT scan in DTC patients with high serum Tg level and negative 131I WBS. 69 post-surgical DTC patients with high serum Tg level and negative post ablation 131I WBS were enrolled in this study. All DTC patients underwent head and neck ultrasound, CT scan and whole-body 18F-FDG PET/CT, based on the dedicated head and neck protocol. Overall, 92 lesions were detected in 43 (62.3%) out of 69 patients with positive 18F-FDG PET/CT scan, compared to only 39 lesions detected on CT scan in 26 (37.7%) out of 69 patients. The sensitivity, accuracy and negative predictive value of 18F-FDG PET/CT were 88%,87% and 76%, respectively, which were significantly higher than those of CT scan (67.2%, 54.3% and 48.8%, respectively) (P<0.01). Specificity and positive predictive value of 18F-FDG PET/CT (90.5% and 95.2%, respectively) were similar to those of CT scan (95.2 % and 96.2 %, respectively) (P>0.05). The maximum standardized uptake value (SUVmax) threshold was 4.5 with a good diagnostic value (sensitivity of 92.3 % and specificity of 100 %). The dedicated head and neck 18F-FDG PET/CT protocol altered the treatment plan in 33 (47.8%) out of 69 DTC patients with high serum Tg level and negative 131I WBS. Dedicated head and neck 18F-FDG PET/CT protocol showed a higher diagnostic value, compared to CT scan and played an important role in detecting recurrent or metastatic lesions in post-surgical DTC patients with high serum Tg level and negative 131I WBS.

Gallium-68 DOTA-DPhe1-Tyr3-Octreotide (68Ga-DOTATOC) has been applied by several European centers for the treatment of a variety of human malignancies. Nevertheless, definitive dosimetric data are yet unavailable. According to the Society of Nuclear Medicine and Molecular Imaging, researchers are investigating the safety and efficacy of this radiotracer to meet Food and Drug Administration requirements. The aim of this study was to introduce the optimized procedure for 68Ga-DOTATOC preparation, using a novel germanium-68 (68Ge)/68Ga generator in Iran and evaluate the absorbed doses in numerous organs with high accuracy. The optimized conditions for preparing the radiolabeled complex were determined via several experiments by changing the ligand concentration, pH, temperature and incubation time. Radiochemical purity of the complex was assessed, using high-performance liquid chromatography and instant thin-layer chromatography. The absorbed dose of human organs was evaluated, based on biodistribution studies on Syrian rats via Radiation Absorbed Dose Assessment Resource Method. 68Ga-DOTATOC was prepared with radiochemical purity of >98% and specific activity of 39.6 MBq/nmol. The complex demonstrated great stability at room temperature and in human serum at 37°C at least two hours after preparation. Significant uptake was observed in somatostatin receptor-positive tissues such as pancreatic and adrenal tissues (12.83 %ID/g and 0.91 %ID/g, respectively). Dose estimations in human organs showed that the pancreas, kidneys and adrenal glands received the maximum absorbed doses (0.105, 0.074 and 0.010 mGy/MBq, respectively). Also, the effective absorbed dose was estimated at 0.026 mSv/MBq for 68Ga-DOTATOC. The obtained results showed that 68Ga-DOTATOC can be considered as an effective agent for clinical PET imaging in Iran.

Lutetium-177 can be made with high specific activity and with no other isotopes of lutetium present, referred to as “No Carrier Added” (NCA) 177Lu. We have radiolabelled DOTA-conjugated peptide DOTA‐(Tyr3)‐octreotate with NCA 177Lu (“NCA-LuTATE”) and used it in nearly 40 therapeutic administrations for subjects with neuroendocrine tumours or meningiomas. In this paper, we report on our initial studies on aspects of the biodistribution and dosimetry of NCA-LuTATE from gamma camera 2D whole body (WB) and quantitative 3D SPECT (qSPECT) 177Lu imaging. Thirteen patients received 39 NCA-LuTATE injections. Extensive WB planar and qSPECT imaging was acquired at approximately 0.5, 4, 24 and 96 h to permit estimates of clearance and radiation dose estimation using MIRD-based methodology (OLINDA-EXM). The average amount of NCA-Lutate administered per cycle was 7839±520 MBq. Bi-exponential modelling of whole body clearance showed half lives for the fast & slow components of t½=2.1±0.6 h and t½=58.1±6.6 h respectively. The average effective dose to kidneys was 3.1±1.0 Gy per cycle. In eight patients completing all treatment cycles the average total dose to kidneys was 11.7±3.6 Gy. We have shown that NCA-LuTATE has an acceptable radiation safety profile and is a suitable alternative to Carrier-Added 177Lu formulations. The fast component of the radiopharmaceutical clearance was closely correlated with baseline renal glomerular filtration rate, and this had an impact on radiation dose to the kidneys. In addition, it has less radioactive waste issues and requires less peptide per treatment.

Considering the fact that the standardized uptake value (SUV) of a normal lung tissue is expressed as x±SD, x+3×SD could be considered as the threshold value to outline the internal tumor volume (ITV) of a lung neoplasm. Three hollow models were filled with 55.0 kBq/mL fluorine18- fluorodeoxyglucose (18F-FDG) to represent tumors. The models were fixed to a barrel filled with 5.9 kBq/mL 18F-FDG to characterize normal lung tissues as a phantom. The PET/CT images of the phantom were acquired at rest. Then, the barrel was moved periodically to simulate breathing while acquiring PET/CT data. Volume recovery coefficient (VRC) was applied to evaluate the accuracy of ITVs. For statistical analysis, paired t-test and analysis of variance were applied. The VRCs ranged from 0.74 to 0.98 and significantly varied among gross tumor volumes for delineating ITV (P<0.01). In two-dimensional PET scans, the motion distance did not affect VRC (P>0.05), whereas VRC decreased with increasing distance in three-dimensional PET scans (P<0.05). The threshold value (x+3×SD) had the potential to delineate the ITV of cancerous tissues, surrounded by lung tissues, particularly in two-dimensional PET images.

The present study was conducted to examine whether the standardized uptake value (SUV) may be affected by the spatial position of a lesion in the radial direction on positron emission tomography (PET) images, obtained via two methods based on time-of-flight (TOF) reconstruction and point spread function (PSF). A cylinder phantom with the sphere (30mm diameter), located in the center was used in this study. Fluorine-18 fluorodeoxyglucose (18F-FDG) concentrations of 5.3 kBq/ml and 21.2 kBq/ml were used for the background in the cylinder phantom and the central sphere respectively. By the use of TOF and PSF, SUVmax and SUVmean were determined while moving the phantom in a horizontal direction (X direction) from the center of field of view (FOV: 0 mm) at 50, 100, 150 and 200 mm positions, respectively. Furthermore, we examined 41 patients (23 male, 18 female, mean age: 68±11.2 years) with lymph node tumors, who had undergone 18F-FDG PET examinations. The distance of each lymph node from FOV center was measured, based on the clinical images. As the distance of a lesion from the FOV center exceeded 100 mm, the value of SUVmax, which was obtained with the cylinder phantom, was overestimated, while SUVmean by TOF and/or PSF was underestimated. Based on the clinical examinations, the average volume of interest was 8.5 cm3. Concomitant use of PSF increased SUVmax and SUVmean by 27.9% and 2.8%, respectively. However, size of VOI and distance from the FOV center did not affect SUVmax or SUVmean in clinical examinations. The reliability of SUV quantification by TOF and/or PSF decreased, when the tumor was located at a 100 mm distance (or farther) from the center of FOV. In clinical examinations, if the lymph node was located within 100 mm distance from the center of FOV, SUV remained stable within a constantly increasing range by use of both TOF and PSF. We conclude that, use of both TOF and PSF may be helpful.

To the best of our knowledge, imaging of accidental exposure to radioactive fluorine-18 (F-18) due to liquid spill has not been described earlier in the scientific literature. The short half-life of F-18 (t½=110 min), current radiation safety requirements, and Good Manufacturing Practice (GMP) regulations on radiopharmaceuticals have restrained the occurrence of these incidents. The possibility of investigating this type of incidents by gamma and positron imaging is also quite limited. Additionally, a quick and precise analysis of radiochemical contamination is cumbersome and sometimes challenging if the spills of radioactive materials are low in activity. Herein, we report a case of accidental F-18 contamination in a service person during a routine cyclotron maintenance procedure. During target replacement, liquid F-18 was spilled on the person responsible for the maintenance. The activities of spills were immediately measured using contamination detectors, and the photon spectrum of contaminated clothes was assessed through gamma spectroscopy. Despite protective clothing, some skin areas were contaminated, which were then thoroughly washed. Later on, these areas were imaged, using positron emission tomography (PET), and a gamma camera (including spectroscopy). Two contaminated skin areas were located on the hand (9.7 and 14.7 cm2, respectively), which showed very low activities (19.0 and 22.8 kBq respectively at the time of incident). Based on the photon spectra, F-18 was confirmed as the main present radionuclide. PET imaging demonstrated the shape of these contaminated hot spots. However, the measured activities were very low due to the use of protective clothing. With prompt action and use of proper equipments at the time of incident, minimal radionuclide activities and their locations could be thoroughly analyzed. The cumulative skin doses of the contaminated regions were calculated at 1.52 and 2.00 mSv, respectively. In the follow-up, no skin changes were observed in the contaminated areas.

Bangladesh is one of the smaller states in Asia. But it has a long and rich history of nuclear medicine for over sixty years. The progress in science and technology is always challenging in a developing country. In 1958, work for the first Nuclear Medicine facility was commenced in Dhaka in a tin-shed known as ‘Radioisotope Centre’ and was officially inaugurated in 1962. Since the late 50s of the last century nuclear medicine in Bangladesh has significantly progressed through the years in its course of development, but still the facilities are inadequate. At present there are 20 nuclear medicine establishments with 3 PET-CTs, 42 gamma camera/SPECTs with 95 physicians, 20 physicists, 10 radiochemists and 150 technologists. The Society of Nuclear Medicine, Bangladesh (SNMB) was formed in 1993 and publishing its official journal since 1997. Bangladesh also has close relationships with many international organizations like IAEA, ARCCNM, AOFNMB, ASNM, WFNMB and WARMTH. The history and the present scenario of the status of nuclear medicine in Bangladesh are being described here.