Determination of [99]Mo contamination in [99m]Tc elute obtained from [99]Mo / [99m]Tc- generator

[99m]Tc is a widely used radioisotope in nuclear medicine centers which is obtained by elution from Mo-[99]/Tc-[99m] generators. Usually the generators are either supplied by the Iran Atomic Energy Agency or by private companies from foreign countries. In this study we have measured [99]Mo contamination in [99m]Tc elute from different generators in a period of one year. The radionuclide impurity of the [99m]Tc elute were studied in two types of radionuclide generators [A: produced in Iran and B: imported from other country]. In-vitro measurements were performed using dose calibrator. Direct measurements were made, using a standard canister at the time of milking of the generators and also in subsequent hours after milking. The results showed a mean of [99]Mo impurity in generators A and B to be 0.00932 +/- 0.0043 and 0.0170 +/- 0.0127 respectively. Although the results showed that the [99]Mo contamination in [99m]Tc elute was lesser than the maximum accepted activity limit of 0.015%, the difference in these two types may reflect different methods of productions of generator, as well as the quality control procedures. The mean of [99]Mo contamination in generators produced in Iran Atomic Energy Organization was lesser than generators imported from foreign origin

[Comparison of left ventricular ejection fraction and ventricular volume in echocardiography and nuclear myocardial perfusion scan]

Radionuclide scanning of the heart has incremental value in diagnosis and risk stratification of coronary artery disease. Gated myocardial perfusion SPECT is a new method and the state of the art in coronary artery disease detection. This study was done to evaluate estimation of LV volume, wall motion diameters and ejection fraction by gated myocardial perfusion scan and make a comparison with trans thoracic echocardiography. In this cross-sectional descriptive study during Sep 2001- Dec 2002, 68 patients suspected of IHD who were referred to nuclear Medicine Department of Imam Reza Hospital in Mashhad University of Medical Sciences were under taken gated myocardial perfusion SPECT, and then referred to echocardiography unit for trans thoracic echocardiography. LV volume, ejection fraction, regional wall motion in different views of 2D-echo was recorded and the results were compared by descriptive statistics. This study was performed on 68 patients. The mean age of patients was 52.8 [min: 38, Max: 75]. 54% of patients were male and 46% were female. Mean end systolic volumes of LV was 32.4ml [sd: 37.1] estimated by echocardiography and 68.3ml [sd: 52.2] stimated by radionuclide scan [pv: 0.00]. Mean end diastolic volume of LV was 129.6ml [sd: 45.8] in echocardiography and 143.7ml [sd: 46.23] in radionuclide scanning [pv: 0.00]. Mean ejection fraction value of LV was 54.6 [sd: 12.44] estimated by echocardiography and 54 [sd: 12.94] by radionuclide scan [pv: 0.00]. Left ventricular end systolic and diastolic volumes and ejection fraction, obtained by gated myocardial perfusion scan and echocardiography, had significant statistic correlations and estimation of LV wall motions and ejection fraction by gated SPECT was as echocardiography

Diuretic effect on the measurement of differential renal function using 99m Tc-DMSA in patients with hydronephrosis

It has been suggested that calculation of differential renal function [DRF] using 99mTc-DMSA may lead to overestimation of the function of an obstructed kidney. The aim of this study was to evaluate the effect of diuretic administration on the determination of DRF using 99mTc-DMSA scintigraphy in patients with dilated pelvis. Thirty three patients, aged from 2 months to 66 years [19.27 +/- 20.83 years, 22 males, 11 females], in whom unilateral hydronephrosis had been documented by ultrasonography and diuretic renography were included in the study. 99mTc-DMSA scintigraphy was performed in all patients 3 hours after tracer injection. Immediately after the standard study, furosemide was injected in all patients, and 30 min later anterior and posterior images were obtained. DRF was calculated for each patient and from each 99mTc-DMSA study by using the geometric mean method. We did not observe any significant difference in all patients between the DRF values obtained before and after diuretic administration [the DRF value of the affected kidney was thus taken into account][P=0.35]. When we compared DRF values obtained from standard and from diuretic DMSA studies, the mean of the differences was only 0.18% and the SD was only 1.09%. In 17 patients [group1], diuresis renography revealed an obstructive curve pattern while 16 patients [group 2] had a nonobstructive dilated renogram curve pattern. There were again no significant differences between DRF values obtained before and after diuretic injection in each group. In view of our study, diuretic administration seems to be an unnecessary intervention because it has no effect on the accuracy of DRF measurements using 99mTc-DMSA scintigraphy in patients with a dilated collecting system whether it is obstructed or not

Complications after dipyridamole infusion in myocardial perfusion SPECT and correlation with homodynamic changes

In Iran dipyridamole is the main agent used for coronary dilatation before myocardial perfusion SPECT. This study tries to evaluate the side effects after dipyridamole infusion and its relation with hemodynamic changes. We studied 300 patients who referred to myocardial perfusion scan. The exclusion criteria were: 1] AV block degree 2 or more, 2] Asthma 3] Sick sinus syndrome 4] LV EF<25%. Dipyridamole infusion was done with a dose of 0.568 mg/kg of body weight for 4 minutes and blood pressure and pulse rate were measured before infusion of dipyridamole and 2 minutes after termination of infusion. Patients were asked for any side effects and any complaints were recorded. Relationship between these side effects and age and sex of patients as well as hemodynamic changes were studied. 148 female and 152 male patients studied with a mean age of 55.9 years [11.1]. After dipyridamole infusion 79.3% of patients had at least one symptom, with headache [50%] and sweating [3%], the most and the least prevalent symptoms respectively. Mean heart rate increment was 8.8 and 9.2 beat per minute in female and male respectively [P=0.59]. Mean systolic blood pressure decrement was 8.5 [8.6] and 9.6 [7.1] mmHg in male and female respectively [P=0.21]. Diastolic pressure decrement was 4.6 [6.7] and 6.8 [6.3] mmHg in male and female respectively [P=0.003]. Headache and flashing were more frequent in female patients [P=0.004]. Other symptoms like dizziness, dyspnea, chest discomfort and abdominal discomfort were not different between female and male patients [P>0.08]. After dipyridamole infusion, nonspecific side effects are frequent. Headache and flashing is more frequent in female patients. Flashing is related to decrement in diastolic blood pressure

[Color doppler and sonographic appearances of thyroid nodules and comparison with the FNA results]

Thyroid node is one of common clinical symptoms. Fine needle aspiration, radioisotope scan and ultrasound are some imaging methods which help us in diagnosis and management of a thyroid node. Ultrasound is a noninvasive method with minimal side effects and we studied diagnostic value of ultrasound and color doppler in thyroid nodules. We studied 66 cases of palpable thyroid node who came to endocrine clinic of Emam-Reza hospital between August 2003-2004 and underwent FNA. These patients were evaluated by sonography and color doppler in radiology department of Ghaem hospital. 8% of the nodules were malignant and 92% were benign. Homogeneous echo pattern suggests benign lesion rather than malignancy. The probability of malignancy is greater in solitary nodule than multiple nodules. In color doppler examination, 91% of benign nodules and 75% of malignant nodules had perilesional vascularity. 60% of malignant nodules and 12% of benign nodules had very high intranodular vascularity, so rich intralesional flow is an indicative of a malignant lesion. RI>0.75 is significantly higher in malignant lesions than benign lesions [P=0.045]

Evaluation of breast scan with[99m] tc-mibi in differential diagnosis of breast masses

Introduction: Breast cancer in women is second only to lung cancer with respect to cancer deaths. Early detection of this cancer is believed to improve patient survival and to prevent metastasis

Material and Method: This descriptive study was designed to evaluate the value of [99m] TC-MIBI-breast scintigraphy in differential diagnosis of breast masses. A total of 20 patients during a 12-months period [from March 2003 to March 2004] in Imam Reza Hospital evaluated. After clinical examinations and breast MIBI scan, excisional biopsy was done

Result: We studied 21 breast masses. 14 masses were malignant tumours and 7 masses were benign tumours. The mean value of MIBI uptake in malignant masses of breast was significantly greater than benign masses [P=0.05]. The sensitivity and specifity of breast scan with [99m] TC-MIBI using qualitative interpretation was 78.5% and 85.7% respectively. The sensitivity and specifity of [99m] TC-MIBI using tumour/background ratio in detection of malignancy was 92.3% and 71.4% respectively

Conclusion: In this study it was found that quantitative interpretation of [99m] TC-MIBI scintimammography considering tumour/background uptake ratio [>1.3] is highly sensitive for detection of breast cancer

optimal time of discontinuing methimzaole before radioiodine therapy

Hyperthyroidism is a common disease and one of the best methods for its treatment is radioiodine therapy. Treatment with antithyroid drugs brings patients to euthyroidism before radioiodine therapy. Antithyroid drugs should be discontinued before radioiodine therapy to increase thyroid uptake. The purpose of this study was to determine the optimal time of methimazole [MTZ] discontinuation. One hundred eighty four patients, who were referred for radioiodine therapy were classified in 3 groups according to the duration of MTZ discontinuation before thyroid uptake [RAIU] measurement. Group 1, 2 and 3 were patients who discontinued MTZ [48-72 hrs], [72-120 hrs] and more than 120 hrs before RAIU measurement, respectively. Mean thyroid uptake in group 1, 2 and 3 was [64 +/- 15.1%], [60.1 +/- 14.1%] and [59.3 +/- 12.8], respectively. No significant difference was noted in thyroid uptake between these groups [F=1.83, P<0.16]. This study shows that 48-72 hrs of MTZ discontinuation before radioiodine therapy is enough and longer term abstention is not associated with higher uptake