Asia Oceania Journal of Nuclear Medicine & Biology
Volume:3 Issue: 1, Winter 2015

Radiation therapy for breast cancer can induce myocardial capillary injury and increase cardiovascular morbidity and mortality. A prospective cohort was conducted to study the prevalence of myocardial perfusion abnormalities following radiation therapy of left sided breast cancer patients as compared to those with right–sided cancer. To minimize potential confounding factors, only those patients with low 10-year risk of coronary artery disease (based on Framingham risk scoring) were included. All patients were initially treated by modified radical mastectomy and then were managed by postoperative 3D Conformal Radiation Therapy (CRT) to the surgical bed with an additional 1-cm margin, delivered by 46-50 Gy (in 2 Gy daily fractions) over a 5-week course. The same dose-adjusted chemotherapy regimen (including anthracyclines, cyclophosphamide and taxol) was given to all patients. Six months after radiation therapy, all patients underwent cardiac SPECT for the evaluation of myocardial perfusion. A total of 71 patients with a mean age of 45.3±7.2 years [35 patients with leftsided breast cancer (exposed) and 36 patients with right-sided cancer (controls)] were enrolled. Dose-volume histogram (DVH) [showing the percentage of the heart exposed to >50% of radiation] was significantly higher in patients with left-sided breast cancer. Visual interpretation detected perfusion abnormalities in 42.9% of cases and 16.7% of controls (P=0.02, Odds ratio=1.46). In semiquantitative segmental analysis, only apical (28.6% versus 8.3%, P=0.03) and anterolateral (17.1% versus 2.8%, P=0.049) walls showed significantly reduced myocardial perfusion in the exposed group. Summed Stress Score (SSS) of>3 was observed in twelve cases (34.3%), while in five of the controls (13.9%),(Odds ratio 1.3). There was no significant difference between the groups regarding left ventricular ejection fraction. The risk of radiation induced myocardial perfusion abnormality in patients treated with CRT on the left hemi thorax is not low. It is reasonable to minimize the volume of the heart being in the field of radiation employing didactic radiation planning techniques. Also it is advisable to screen these patients with MPI-SPECT, even if they are clinically asymptomatic, as early diagnosis and treatment of silent ischemia may change the outcome.

In this study, we aimed to describe the characteristics of portal vein tumor thrombosis (PVTT), complicating hepatocellular carcinoma (HCC) in contrast-enhanced FDG PET/CT scan. In this retrospective study, 9 HCC patients with FDG-avid PVTT were diagnosed by contrast-enhanced fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT), which is a combination of dynamic liver CT scan, multiphase imaging, and whole-body PET scan. PET and CT DICOM images of patients were imported into the PET/CT imaging system for the re-analysis of contrast enhancement and FDG uptake in thrombus, the diameter of the involved portal vein, and characteristics of liver tumors and metastasis. Two patients with previously untreated HCC and 7 cases with previously treated HCC had FDG-avid PVTT in contrast-enhanced FDG PET/CT scan. During the arterial phase of CT scan, portal vein thrombus showed contrast enhancement in 8 out of 9 patients (88.9%). PET scan showed an increased linear FDG uptake along the thrombosed portal vein in all patients. The mean greatest diameter of thrombosed portal veins was 1.8 ± 0.2 cm, which was significantly greater than that observed in normal portal veins (P<0.001). FDG uptake level in portal vein thrombus was significantly higher than that of blood pool in the reference normal portal vein (P=0.001). PVTT was caused by the direct extension of liver tumors. All patients had visible FDG-avid liver tumors in contrast-enhanced images. Five out of 9 patients (55.6%) had no extrahepatic metastasis, 3 cases (33.3%) had metastasis of regional lymph nodes, and 1 case (11.1%) presented with distant metastasis. The median estimated survival time of patients was 5 months. The intraluminal filling defect consistent with thrombous within the portal vein, expansion of the involved portal vein, contrast enhancement, and linear increased FDG uptake of the thrombus extended from liver tumor are findings of FDG-avid PVTT from HCC in contrast-enhanced FDG PET/CT.

Objective (s): This study aimed to compare the diagnostic values of 11C-choline and 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in patients with cholangiocarcinoma (CCA). This prospective study was conducted on 10 patients (6 males and 4 females)، aged 42-69 years، suspected of having CCA based on CT or magnetic resonance imaging (MRI) results. 11C-choline and 18F-FDG PET/CT studies were performed in all patients over 1 week. PET/CT results were visually analyzed by 2 independent nuclear medicine physicians and quantitatively by calculating the tumor-to-background ratio (T/B). No 11C-choline PET/CT uptake was observed in primary extrahepatic or intrahepatic CCA cases. Intense 18F-FDG avidity was detected in the tumors of 8 patients (%80). Two patients، who were 18F-FDG negative، had primary extrahepatic CCA. Ki-67 measurements were positive in all patients (range; 14. 2%-39. 9%). The average T/B values of 11C choline and 18F-FDG were 0. 4±0. 2 and 2. 0±1. 0 in all cases of primary CCA، respectively; these values were significantly lower for 11C-choline (P 0. 005). Both FDG and 11C-choline PET/CT detected metastatic CCA foci in all 8 patients (two patients had no metastases). As the results suggested، primary CCA lesions showed a poor avidity for 11C-choline، whereas 18F-FDG PET/CT was of value for the detection of most primary CCA cases. In contrast to primary lesions، metastatic CCA lesions showed 11C-choline avidity.

We investigated a frequency of lower extremity uptake on the radioactive iodine (RAI) whole body scan (WBS) after RAI treatment in patients with differentiated thyroid cancer, in order to retrospectively examine whether or not the frequency was pathological. This retrospective study included 170 patients with thyroid cancer, undergoing RAI treatment. Overall, 99r (58%) and 71 (42%)patients received single and multiple RAI treatments, respectively. Post-therapeutic WBS was acquired after 3 days of RAI administration. For patients with multiple RAI treatments, the WBS of their last RAI treatment was evaluated. Lower extremity uptake on post-therapeutic WBS was classified into 3 categories: bilateral femoral uptake (type A), bilateral femoral and tibia uptake (type B), and uptake in bilateral upper and lower extremities (type C). Then, the patients with RAI uptake in the lower extremities on WBS were analyzed with clinical parameters. Overall, 99 patients (58%) had the extremity uptake on their posttherapeutic RAI WBS. As the results indicated, 42, 53, and 4 patients had type A, type B, and type C uptakes, respectively. Lower extremity uptake was significantly associated with younger age, not only in subjects with multiple RAI treatments but also in all the patients (P<0.05). Accumulation in patients with multiple RAI treatments was more frequent than patients with single RAI treatment (P<0.05). Lower extremity uptake was not associated with counts of the white blood cell count, hemoglobin level, platelet count, estimated glomerular filtration rate, effective half-time of RAI, serum TSH level, and anti-Tg concentration. About half of the patients had lower extremity uptake on the posttherapeutic RAI WBS, especially younger patients and those with multiple courses of RAI treatment. Bilateral lower extremity’s RAI uptake on the posttherapeutic WBS should be considered as physiological RAI distribution in bone marrow.

Recently, bone-avid radiopharmaceuticals have been shown to have potential benefits for the treatment of widespread bone metastases. Although 17 Lutriethylene tetramine hexa methylene phosphonic acid (abbreviated as 177Lu- TTHMP), as an agent for bone pain palliation, has been evaluated in previous studies, there are large discrepancies between the obtained results. In this study, production, quality control, biodistribution, and dose evaluation of 177Lu-TTHMP have been investigated and compared with the previously reported data. TTHMP was synthesized and characterized, using spectroscopic methods. Radiochemical purity of the 177Lu-TTHMP complex was determined using instant thin-layer chromatography (ITLC) and high performance liquid chromatography (HPLC) methods. The complex was injected to wild-type rats and biodistribution was studied for 7 days. Preliminary dose evaluation was investigated based on biodistribution data in rats. 177Lu was prepared with 2.6-3 GBq/mg specific activity and radionuclide purity of 99.98%. 177Lu-TTHMP was successfully prepared with high radiochemical purity (>99%). The complex showed rapid bone uptake, while accumulation in other organs was insignificant. Dosimetric results showed that all tissues received almost insignificant absorbed doses in comparison with bone tissues. Based on the obtained results, this radiopharmaceutical can be a good candidate for bone pain palliation therapy in skeletal metastases.

The energy resolution of a cadmium-zinc-telluride (CZT) solid-state semiconductor detector is about 5%, and is superior to the resolution of the conventional Anger type detector which is 10%. Also, the window width of the high-energy part and of the low-energy part of a photo peak window can be changed separately. In this study, we used a semiconductor detector and examined the effects of changing energy window widths for 99mTc and 123 I simultaneous SPECT. The energy “centerline” for 99mTc was set at 140.5 keV and that for 123I at 159.0 keV. For 99mTc, the “low-energy-window width” was set to values that varied from 3% to 10% of 140.5 keV and the “high-energy-window width” were independently set to values that varied from 3% to 6% of 140.5 keV. For 123I, the “low energy-window-width” varied from 3% to 6% of 159.0 keV and the high-energy-window width from 3% to 10% of 159 keV. In this study we imaged the cardiac phantom, using single or dual radionuclide, changing energy window width, and comparing SPECT counts as well as crosstalk ratio. The contamination to the 123I window from 99mTc (the crosstalk) was only 1% or less with cutoffs of 4% at lower part and 6% at upper part of 159KeV. On the other hand, the crosstalk from 123I photons into the 99mTc window mostly exceeded 20%. Therefore, in order to suppress the rate of contamination to 20% or less, 99mTc window cutoffs were set at 3% in upper part and 7% at lower part of 140.5 KeV. The semiconductor detector improves separation accuracy of the acquisition inherently at dual radionuclide imaging. In, this phantom study we simulated dual radionuclide simultaneous SPECT by 99mTc tetrofosmin and 123 I-BMIPP. We suggest that dual radionuclide simultaneous SPECT of 99mTc and 123I using a CZT semiconductor detector is possible employing the recommended windows.

Primary hepatic neuroendocrine tumors (PHNETs) are extremely rare neoplasms. Herein, we report a case of a -70year-old man with a hepatic mass. The non-contrast computed tomography (CT) image showed a low-density mass, and dynamic CT images indicated the enhancement of the mass in the arterial phase and early washout in the late phase. F18- fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) and fused PET/CT images showed increased uptake in the hepatic mass. Whole-body 18F-FDG PET images showed no abnormal activity except for the liver lesion. Presence of an extrahepatic tumor was also ruled out by performing upper gastrointestinal endoscopy, total colonoscopy, and chest and abdominal CT. A posterior segmentectomy was performed, and histologic examination confirmed aneuroendocrine tumor (grade 1). The patient was followed up for about 2 years after the resection, and no extrahepatic lesions were radiologically found. Therefore, the patient was diagnosed with PHNET. To the best of our knowledge, no previous case of PHNET have been detected by 18F-FDG PET imaging

In this study, we aimed to analyze the relationship between the diagnostic ability of fused single photon emission computed tomography/computed tomography (SPECT/CT) images in localization of parathyroid lesions and the size of adenomas or hyperplastic glands. Five patients with primary hyperparathyroidism (PHPT) and 4 patients with secondary hyperparathyroidism (SHPT) were imaged 15 and 120 minutes after the intravenous injection of technetium9 mmethoxyisobutylisonitrile (99mTc-MIBI). All patients underwent surgery and 5 parathyroid adenomas and 10 hyperplastic glands were detected. Pathologic findings were correlated with imaging results. The SPECT/CT fusion images were able to detect all parathyroid adenomas even with the greatest axial diameter of 0.6 cm. Planar scintigraphy and SPECT imaging could not detect parathyroid adenomas with an axial diameter of 1.0 to 1.2 cm. Four out of 10 (40%) hyperplastic parathyroid glands were diagnosed, using planar and SPECT imaging and 5 out of 10 (50%) hyperplastic parathyroid glands were localized, using SPECT/CT fusion images. SPECT/CT fusion imaging is a more useful tool for localization of parathyroid lesions, particularly parathyroid adenomas, in comparison with planar and or SPECT imaging.

The aim of this study was to determine whether high-dose radioactive iodine (Na131I) outpatient treatment of patients with thyroid carcinoma is a pragmatically safe approach, particularly for the safety of caregivers. A total of 79 patients completed the radiation-safety questionnaires prior to receiving high-dose radioactive iodine treatment. The questionnaire studied the subjects’ willingness to be treated as outpatients, along with the radiation safety status of their caregivers and family members. In patients, who were selected to be treated as outpatients, both internal and external radiation exposures of their primary caregivers were measured, using thyroid uptake system and electronic dosimeter, respectively. Overall, 62 out of 79 patients were willing to be treated as outpatients; however, only 44 cases were eligible for the treatment. The primary reason was that the patients did not use exclusive, separated bathrooms. The caregivers of 10 subjects, treated as outpatients, received an average radiation dose of 138.1 microsievert (mSv), which was almost entirely from external exposure; the internal radiation exposures were mostly at negligible values. Therefore, radiation exposure to caregivers was significantly below the public exposure limit (1 mSv) and the recommended limit for caregivers (5 mSv). A safe 131I outpatient treatment in patients with thyroid carcinoma could be achieved by selective screening and providing instructions for patients and their caregivers.