Iranian Journal of Nuclear Medicine
Volume:18 Issue: 1, Winter-Spring 2010

Sentinel lymph node biopsy is the standard procedure for lymph node staging in intermediate thickness melanoma. In Iran, this procedure has not been addressed sufficiently. In this study, we report our experience in this area. Ten consecutive patients with intermediate thickness melanoma where included in our study. 1.5 mCi of Tc-99m antimony sulfide colloid in two divided dose was injected around the tumor. All patients underwent surgery 2-4 hours after injection of the tracer. Patent blue V dye was also used for 8 patients. Using a hand-held gamma probe, the sentinel nodes were harvested and sent to the pathologist for frozen section and H&E review. For patients with positive sentinel nodes, lymph node dissection was performed. At least one sentinel node could be harvested in all patients. The mean number of sentinel nodes was 1.66. Detection rate with radiotracer and blue dye was 100% and 75% respectively. 30% of the patients had positive sentinel nodes. One patient in the pediatric age range and one head and neck melanoma were included in our study with successful sentinel node mapping. Sentinel lymph node biopsy using Tc-99m antimony sulfide colloid is a reliable and safe method in melanoma patients which can help in treatment planning and patient's ultimate prognosis

Percutaneous transluminal coronary angioplasty (PTCA) is an effective method for revascularizing of stenotic coronary vessels. Lack of response to this treatment, either in symptomatic or asymptomatic patients, is usually due to incomplete revascularization, restenosis, and/or irreversibility of myocardial perfusion. Introduction of a noninvasive method with high predictive value for diagnosis of reversibility in ischemic myocardium is of high importance to determine the patients who will benefit from PTCA. Sixty patients with one or two vessel disease, who were candidates for PTCA and had a successful PTCA (proved by post- revascularization angiography), enrolled the study. For all patients myocardial perfusion imaging (MPI) was performed before PTCA in stress and rest phases. MPI was repeated in stress and rest phases within 6 months after PTCA. The predictive values of pre-PTCA scan for the diagnosis of reversibility and prediction of perfusion improvement after PTCA were evaluated. Perfusion improvement after PTCA was noted in 52 of 60 patients (86.7%). The positive predictive value of pre-intervention MPI for diagnosis of reversibility was 94.3% and the corresponding negative predictive value was 71.4%. Myocardial perfusion imaging may play an important role for accurate prediction of perfusion improvement after percutaneous transluminal coronary angioplasty.

[61Cu]diacetyl-bis(N4-methylthiosemicarbazone) ([61Cu]ATSM) is a well-established hypoxia imaging tracer with simple production and significant specifity. In this work the accumulation of the tracer is studied in wild-type, necrotic and hypoxic fibrosarcoma tumors. [61Cu]ATSM was prepared using ATSM ligand and [61Cu]CuOAc followed by i.v. administration and imaging studies in wild-type rats and hypoxic fibrosarcoma-bearing mice. [61Cu]ATSM with high radiochemical purity (>99%, HPLC, RTLC) was injected to wild-type rats as well as hypoxic and necrotic fibrosarcoma-bearing mice followed by imaging up to 3 hours. [61Cu]ATSM was mainly accumulated in liver, as well as kidney and bladder and less but still significant in brain of wild-type rats. A significant and hypoxia-specific tumor/non tumor ratio in hypoxic models was observed by co-incidence imaging 2 h post injection, while in necrotic and 12-week tumor-induced mice very slight tumor uptakes were detected. [61Cu]ATSM is a positron emission tomography (PET) radiotracer for selective tumor hypoxia imaging from necrotic and proliferative tumors.

Developing new radiosynovectomy agents is of great importance due to the aging of human populations around the world and increasing the incidence of inflammatory diseases. In this work, Sm-153 chitosan agent was developed for the first time in our country and preparation and quality control of the compound is described. Sm-153 chloride was obtained by thermal neutron flux (4-5 × 1013 n.cm-2.s-1) of natural Sm2O3 sample, dissolved in acidic media. 153Sm-samarium chloride (370 MBq) was used in preparation of 153Sm-chitosan complex followed by quality control using MeOH: H2O: acetic acid (4: 4: 2) as mobile phase. The complex stability and viscosity were checked in the final solution up to 2 days. The complex solution and 153Sm3+ (80 µCi/100 µl) were injected intra-articularly into male rat knee joint followed by scarification studies 6 d post injection. Sm-153 chitosan was prepared successfully with high radiochemical purity (>99%, ITLC) at room temperature after 10-30 min followed by autoclave sterilization. The complex was stable at room temperature and 37ºC up to 2 days. No significant leakage of dose from injection site and its distribution in organs were observed up to 6 days for 153Sm-chitosan. Approximately, more than 90% of injected dose remained in injection site after 6d. The complex is a dedicated agent for radiosynovectomy. The experience from this study would lead to the development of more sophisticated radiosynovectomy radiopharmaceutcals for human use in the country.

Using beta emitter radionuclide is a useful therapeutic modality in the treatment of skin cancers in areas which are difficult to cure by other methods. The aim of this research is to evaluate the tissue response to beta rays of 166Ho and determine the feasibility of beta emitting radionuclide for treatment of skin cancers. In this work, we have calculated depth dose distribution of 166Ho using Varskin3 code. The code has been run for various input parameters to calculate absorbed depth dose for different shape of source. Absorbed depth dose variation has been calculated for166Ho beta emitter, in different shape of sources such as slab, spherical, cylindrical and 2-D disk shapes. Comparison of the result for different shape sources has been presented. The result shows that 2-D disk source induces damage to skin cells more than other shape of sources. These computational and Lee et al. experimental results are shown that 166Ho radionuclide treatment is very useful for skin cancer therapy. One of advantages of using 166Ho radionuclide is that no adverse effect on underlying bone and soft tissue due to the physical characteristics of beta rays, high linear energy transfer or rapid depth dose fall off is observed.

Iranian scorpion species are classified in Buthidae and Scorpionidae with 16 genera and 25 species. In Iran, similar to other parts of the world, there are a few known species of scorpions responsible for severe envenoming. Mesobuthus eupeus is the most common species in Iran. Its venom contains several toxin fractions which can affect the ion channel. In this study purification, labeling and biological evaluation of Mesobuthus eupeus scorpion venom are described. To separate different venom fractions, soluble venom was loaded on a chromatography column packed with sephadex G50 gel then the fractions were collected according to UV absorption at 280 nm wavelength. Toxic fraction (F3) was loaded on anionic ion exchanger resin (DEAE) and then on a cationic resins (CM). Finally toxic fraction F319 was labeled with 99mTc and radiochemical analysis was determined by paper chromatography. The biodistribution was studied after injection into normal mice. Toxic fraction of venom was successfully obtained in purified form. Radiolabeling of venom was performed at high specific activity with radiochemical purity more than 95% which was stable for more than 4 h. Biodistribution studies in normal mice showed rapid clearance of compound from blood (2.64% ID at 4 h) and tissues except the kidneys (27% ID at 4 h). As tissue distribution studies are very important for clinical use, results of this study suggest that 99mTc labeling of venom can be a useful tool for in vivo studies and is an excellent approach to follow the process of biodistribution and kinetics of toxins.

Although PET scanning using F-18[FDG] is considered the superior radiotracer for tumnor imaging, Gallium-67 is still in use for some malignancies such as lymphoma and hepatoma. One of the strategies to improve the diagnostic accuracy of Gallium is to perform SPECT which is reported to be more sensitive compared to planar imaging. In this study we compared the sensitivity of SPECT and planar imaging in patients suspicious of thoracic recurrent lymphoma. 129 patients with suspicious recurrent lymphoma of the thorax were included into the study. All patients received 10 mCi Gallium-67-citrate intravenously. Twenty four and 48 hours post injection whole body and thoracic SPECT imaging was performed. The final diagnosis of recurrence was achieved by combination of clinical and imaging findings or pathologic examination whenever possible. The final diagnosis of 83 (64.3%) patients was recurrence of lymphoma in the thoracic area and the remainder 46 (35.7%) were in remission. The sensitivity of planar and SPECT imaging for diagnosis of recurrent lymphoma was 63% ([52-73%] with 95% confidence intervals) and 87% ([79-94%] with 95% confidence intervals), respectively. In our study, 20 patients with the final diagnosis of lymphoma recurrence in the thoracic area had negative planar despite positive SPECT imaging. This showed an increase of 24% in sensitivity of the scan (from 63% to 87%) by adding SPECT imaging to the procedure. Our recommendation is integrating SPECT modality into all gallium scintigraphy for lymphoma recurrence.

Anaplastic thyroid carcinoma is an uncommon, highly aggressive malignancy usually presenting in the elderly. An eighteen year old boy was recently diagnosed as anaplastic carcinoma of the thyroid. PET/CECT scan performed for staging, revealed a large FDG avid heterogeneously enhancing thyroid mass with bilateral jugular venous thrombosis, which also showed increased FDG uptake, thus pointing towards tumor thrombus. To our knowledge, this is the first case wherein the PET/CT diagnosis of tumor thrombosis from anaplastic thyroid carcinoma was made in a young patient.

A 29- year old female with bone pain and history of precocious puberty was referred for bone scintigraphy. On physical examination café au lait macular spots were noted on her neck, buttocks and left leg. Bone scan showed multiple areas of intense increased activity which was in favour of polyostotic fibrous dysplasia. Considering the presence of polyostotic fibrous dysplasia, precocious puberty and café au lait macular spots, MacCune-Albright syndrome was confirmed in this patient.

A 65 year-old overweight man with a history of prostate cancer was referred to our nuclear medicine department for bone scanning. Anterior projection images showed two small foci of increased radiotracer uptake corresponding to the anterior arcs of the right and left sixth ribs, which were interpreted as suspicious for metastatic involvement. Eight months later the patient was referred for follow-up bone scan. In the follow-up scan, those two foci of abnormal radiotracer activity were outside the limits of the bony structures of the chest. In fact, those foci changed their position and were due to radiotracer uptake by the enlarged breasts of this gentelman (Gynecomastia). Previously, it has been just one report concerning radiotracer uptake in the breasts of a man. Based on our case report, this abnormal finding is not exclusively observed in women and it can be also seen in men who suffer from gynecomastia. Physical examination in these settings can be extremely helpful. Oblique, lateral and SPECT (Single Photon Emission Tomography) views can also confirm the extraskeletal origin of radiotracer uptake.