Iranian Journal of Nuclear Medicine
Year:2004 | Volume:- | Issue:22|Papers Count:9

Aim: Thyroid scan with sestamibi is used for evaluation of thyroid nodules with the aim of increasing specificity before surgery. In this study we evaluated the role of Sestamibi thyroid scan in candidates for thyroid surgery.Methods and patients: During two years, 37 patients were studied with solitary thyroid nodules, referred for thyroid surgery due to malignant or suspicious FNAB results (66/7%), compressive effects or failure of medical therapy. Thyroid scan was performed after IV injection of 15mCi of Tc-99m-MIBI in 4 phases (Angiography-First 10 minutes-15min and 2-3 hours after injection). Thyroid MIBI uptake was scaled in 5 scores (0-4) with no uptake as score 0 and hot nodule as score 4. Patients underwent thyroid surgery and results of pathology are correlated with MIBI uptake. Results: From 37 patients (27female, 10 male, mean age=35.5 years+/- 13.6) 16 malignant and 21 benign nodules were detected. In another classification, we had 26 neoplastic and 11 non-neoplastic nodules. MIBI uptake score 3-4 was noted in 11 out of 16 malignant nodules and 13 out of 21 benign nodules (P=0.73). Sensitivity and specificity of high MIBI uptake (score 3-4)for diagnosis of malignancy was 68.7% and38% respectively. The values for sensitivity and specificity were 69.2% and 30.7% in diagnosis of neoplasm respectively. Washout index (considered as difference in uptake scores of late and early phases) was 0.45 in benign and 0.09 in malignant nodules (P=0.07). The values were 0.26 and 0.37 in neoplastic and non-neoplastic nodules respectively (P=0.65).Conclusion: Thyroid MIBI scan has a low specificity for differentiating malignant from benign or neoplastic from non-neoplastic nodules in patients who are candidates for thyroid surgery according to clinical evaluation. Analysis of wash out index may increase specificity.

67Gallium-bleomycin complex (67Ga-BLM) was prepared using Thakour method. Radio-thin-layer- chromatography of prepared complex showed A2 and B2 radio peaks with Rƒ at 0.7 and 0.4 respectively with a purity of above % 95. Tissue uptake of 67Ga-BLM and 67GaCl3 in twelve tissues including tumor, blood, liver, lung, spleen, muscle, skin, heart, kidney, colon, colon content ,bladder and the total body were counted by well counter at I, 2, 4, 24 and 48 hours post injection of radiopharmaceuticals. Uptakes of tissues are expressed as percent injected dose per gram of tissue. The clearance rate of 67Ga-BLM was 1.75-1.95 times faster than 67GaCl3 at all time intervals. Bladder uptakes of 67Ga-BLM were highest among twelve tissues at 1,2 and 4 hours after injection, then falling rapidly after 24 and 48 hours. Blood uptake of 67Ga-BLM was lower than 67GaCl3 in all time intervals. Colon content uptake of 67Ga-BLM was highest among twelve tissues at 2 and 4 hours post injection. Tumor to' tissue activity ratios were also calculated, showing an increase of tumor to blood and muscle ratios. Tumor to blood ratio increased from 0.3 at 1 hour to 5.3 at 48 hours. Activity ratio of muscle increased from 0.5 at 1 hour to 5.5 at 48 hours. Whole body counting of animals showed that effective half lives of 67Ga-BLM and 67GaCl3 were about 1 and 15 hours respectively, which renders faster excretion of 67Ga-BLM complex. Biodistribution data clearly indicates that prepared complex in comparison with carrier free 67Ga(67GaCh) has two main advantages: 1) high tumor to soft tissue uptake ratio that make it suitable for tumor imaging, 2) faster excretion specially at first three hours post injection. In addition complex is stable in vitro and in vivo.

Introduction: Radioiodine (131I) is an effective and inexpensive alternative to surgery in the treatment of thyroid hyperfunction. The debate today concerns the maximum and minimum ablative doses, and factors leading to hypothyroidism.Patients & Method: 1035 hyperthyroid patients treated with weight-adjusted ablative doses of 131I were retrospectively assessed for treatment outcome or correlated with sex, age, underlying pathology, and administrated dose of 131I.Results: Thyroid hyperfunction was 3.5 times more common in women. The greatest proportions of patients were in the 31-40 years age group and the smallest proportion over-70. The commonest underlying pathology was Grave's disease. Men had a lower response rate to 131I therapy, with 2.4-fold greater probability of persistent hyperthyroidism (P<0.0001). The probability of post-131I hypothyroidism decreased with increasing age (P<0.0001).The best response to 131I therapy was seen in patients with toxic adenoma, (P=0.0001). The incidence of hypothyroidism did not show a positive collection with increased administered dose of 131I (P<0.001).Average time to develop clinical hypothyroidism was 7.1 months. 131I was effective in reducing thyroid nodule size. There were 18 cases of temporary hypothyroidism, all of which recovered to euthyroid status within 12 months.Conclusion: One dose of radioiodine was effective in treatment of hyperthyroid patients in 91.2% of cases. Age, sex and underlying pathology were determining factors. In most cases the average time to hypothyroidism was reasonably short, obviating the need for long time follow up in these patients.

Introduction: Differentiating between ischemic cardiomyopathy (ICM) and idiopathic dilated cardiomyopathy (IDCM) is important as coronary revascularization can improve prognosis in the ischemic subgroup. Due to inherent problems of coronary angiography in patients with depressed ejection fraction (EF). introducing a noninvasive tool to diagnose those who will benefit from angiography seems to be rewarding. We examined usefulness of myocardial perfusion scan in this group of patients. Materials and methods: Study was performed on 64 patients (62 male and 2 female) aged 57.1±6.7y(mean ±SD) all with dilation of the left ventricular (LV) cavity and ejection fraction less than 40% by echocardiography. Myocardial perfusion scan was performed in stress and rest phases. All the patients had coronary angiography which was used as the gold standard test. On each set of images, heart was arbitrary divided into 17segments and perfusion abnormality in each segment was scored by a 5 grade scoring system (0-4). Summed Stress Score was used as the scan criteria to differentiate dilated ischemic from idiopathic cardiomyopathy. Scores more than 17 were considered ischemic, and less than that, idiopathic. Results were compared with angiography.Results: From total 40 cases of ischemic cardiomyopathy (proved by angiography) 39 were correctly diagnosed by scan and only one case was miscategorized as IDCM. All 24 cases of IDCM were correctly diagnosed by scintigraphy. Sensitivity, specificity, positive predictive value, and negative predictive value of myocardial perfusion imaging for discrimination between ischemic and idiopathic dilated cardiomyopathy were 97.5%,100%,100%; and 96% respectively. Conclusion: Considering excellent accuracy of myocardial perfusion scan with scoring sysiem in discrimination of ischemic dilated cardiomyopathy from idiopathic dilated cardiomyopathy, this noninvasive test could be considered the main diagnostic test.

Metastatic survey of the patients with known primary malignancies with bone scan is one of the most common studies in nuclear medicine. Unfortunately the conventional planar bone scan has a very low specificity for differentiating benign from malignant lesions. especially in the spinal column. In this study, we compared the specificity of SPECT imaging and conventional planar bone scan. We studied 20 patients (12.male and 8female) with known primary malignancy, which, had abnormal increased uptake in the spinal column on the planar images.SPECT of the spine was performed for all of these patients. Lesions of the body and pedicles were considered malignant (45 and 37 lesions respectively).and lesions of the anterior rim of the body, spinal and transverse processes and laminas were considered benign (15,6, 5 and 2 lesions respectively). The results of the SPECT were correlated with MRI of the spine or the results of biopsy. 21 out of 24 benign lesions were correctly diagnosed by SPECT imaging. Specificity, positive and negative predictive values of the SPECT were 87.5%,96.3% and 75%respectively. On the other hand the specificity of the conventional planar imaging was 30%. According to the results of this study, the SPECT imaging of the spinal column can be very useful for differentiating benign from malignant causes of abnormal increased uptake of the spine.Particularly lesions located in the vertebral bodies and pedicles should be considered malignant and lesions of the anterior border of the vertebral bodies as benign degenerative changes.

introduction: Hydronephrosis is one of the major causes of referring infants for nuclear medicine investigation. Renal dynamic study is the most reliable investigation for such children. However direct evaluation of renogram leads to generation of parameters that have no physiological interpretation. The configuration of renogram is very much dependent upon the rate at which radiopharmaceutical enters the kidney. In order to decrease such effect, the radiopharmaceutical has to be injecte4iha small volume and very fast into the vein, which is not always possible, especially in the infants. Disconsolation is a method in which the injection quality does not have any. effect upon renogram decreasing the diagnostic errors. The renal retention function (RRF) is independent of input function and derived parameters have physiological significance and clinical values.Materials & methods: In this study 54patients data were evaluated. All the patients were under 6 month of age, suspicious for hydronephrosis referred to our imaging center for 99mTc-DTPA renal dynamic studies. All data were transformed into interfile format. Full renal package software was developed in visual basic 6 to read and process the data. Disconsolation was performed using matrix algorithm. Background subtraction was performed using conventional and Ruthland- Patlack method. All transit time parameters were calculated in 6 different filtering conditions.Results & discussion: Our results show that disconsolation is useful for evaluation of infant hydronephrosis. Mean transit time is the most useful parameter for estimation of renal function in infants.