Iranian Journal of Nuclear Medicine
Volume:9 Issue: 1, 2001

Unilateral condylar hyperplasia is the main cause of mandibular asymmetry. Radionuclide bone scanning is a useful procedure for functional evaluation of temporomandibular joint. In this study, 39 patients with normal bone scan and no facial asymmetry were studied. All patients were below 22 years of age. Normal condylar uptake was determined in this group of patients. Right & left condylar uptakes were not completely identical and some difference (Below 10%) between right and left condylar uptake was seen. No significant difference in condylar uptake in male & female patients were observed (P=0.26, α=0.05).

Radioisotope scanning is the best method for objective assessment of salivary gland function. Thus, it was used in a randomized trial of concomitant pilocarpine for assessment of radiation-induced xerostomia, in addition to subjective evaluation by an approved questionnaire and objective standard xerostomia grading. Patients randomized in placebo-controlled trial of pilocarpine concurrent with irradiation for prevention of radiation-induced xerostomia were evaluated by salivary gland scintigraphy immediately before and 6 months after the end of head and neck radiotherapy. Salivary gland function was measured by ejection fraction (EF) of Technetium-99m pertechnetate. The mean values for pre and post-radiotherapy scans were calculated and compared. Also post-radiotherapy scan findings in the two groups of pilocarpine and placebo were compared using the student’s t-test. In addition, comparison was made between the scan results and the subjective findings and objective gradings. Twenty patients underwent the pre-radiotherapy salivary scintigraphy, and also 20 post-radiotherapy scans were performed. Mean parotid EF was 60.85% in the pre-radiotherapy and 9.08% in the post-radiotherapy scans (P<0.01). The means for submandibular glands in the pre and post-radiotherapy scans were 41% and 11.2%, respectively (P<0.01). Also the mean EF was 14.5% in the pilocarpine group and 3.65 in the placebo group for parotid glands (P=0.07) and 18.3% and 4.1% respectively for submandibular glands (P<0.05). The salivary scans confirmed the subjective and objective xerostomia findings. Salivary gland scintigraphy is a valuable method for evaluation of xerostomia after head and neck radiotherapy, quantitatively demonstrating the protective effect of pilocarpine compared to placebo on salivary glands.

This study was performed to evaluate the Tc-pyp SPECT role in determination of AMI severity and extension. Pyp SPECT imaging was done for 54 patients with AMI, who met the WHO criteria. SPECT findings were correlated with LVEF measurements. The abnormal scan was graded according to the intensity and was compared with the activity of the sternum in the same image. In addition, a segmental myocardial model was used for location determination of abnormal tracer uptake. Resting LVEF was determined by 2D echocardiography in each patient 2 weeks after onset of pain. 79 patients had positive pyp SPECT scans. According to pyp uptake intensity, good correlation between severity and extension of pyp uptake and LVEF was seen. These factors can be considered suitable for prognosis estimation in early post AMI period.

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.

A retrospective study was undertaken to examine the thyroid cancer cases referred for external radiotherapy to our department during the period of 1991-99. Within this period, a total of 33 patients had been treated by irradiation for thyroid cancer or its metastases and these cases were evaluated for age, sex, pathology and type of surgery. The reason of patients’ referral for external radiotherapy (The main aim of our study) was tumor extensive infiltration of the neck soft tissue and/or lymph nodes in 21 cases (64%), and tumor metastasis in 12 cases (36%). Twenty-one patients came back for follow-up, who were all symptom-free 12-18 months after irradiation.

In nuclear medicine, there are two methods of imaging, planar and tomography. Single photon emission computerized tomography (SPECT) shows better image details and therefore is influenced more by image parameters such as resolution, uniformity, sensitivity, etc. Manufacturers provide customers with data which are obtained by complicated and sometimes secret methods. Marketing companies test and verify these data and buyers perform acceptance testing on installation of system. Since acceptance testing is not usually done in our country, follow up of system performance and therefore setting up of a comperehensive quality control program faces difficulty. In this research which was done sometimes after installation, evaluation of SPECT system was carried out and data obtained were compared with those of manufacturer catalogue. It was found that in most cases our figures do not correspond to those of manufacturer catalogue, therefore acceptance testing using standard and precision devices being carried out by trained personnel is strongly recommended.

The main concern with respect to discharge of patients from hospital after 131-I therapy is contamination of their surroundings and exposure of people who are in close contact with them. In this study, we evaluated absorbed dose received by homemates of these patients within one week of discharge from hospital. This study was based on 100 patients (23 patients with thyroid cancer together with 70 members of their families and 2 hyperthyroid patients plus 5 of their family members). Measurements were performed by TLD. Patients were discharged from hospital if the dose rate from a meter distance of their thyroid was below 20 μSv/hr (ICRP-60). The hospitalization period for those patients with thyroid cancer varied between 2-3 days (Depending on the amount of radioactivity received). Hyperthyroid patients were treated as outpatients. Our data indicate that although hyperthyroid patients received much less activity in comparison to those with thyroid cancer, but due to the slow iodine discharge rate from their bodies, they radiated more to their surroundings. For patients with thyroid cancer, when the given activity increased from 100 mCi to 150 mCi, the average dose absorbed by their family members increased by a factor of 3. The duration of hospitalization as well as the amount of activity given to the patients have a significant effect on the amount of radiation dose received by the family members. In a group of patients who received 100 mCi of 131-I, the average radiation dose received by the family members of those patients who were hospitalized for 2 days were 1.5 times more than that of those patients who were hospitalized for 3 days, whereas following therapy with 150 mCi of 131-Iodine, the average radiation dose received by the family members of those patients who were hospitalized for 2 days were about 6.5 times more than that of those who were hospitalized for 3 days. The size of the patient’s house and the time that family spends with the patient at house are other considerable factors. Our data show that by increasing the house size from 45-50 m to 75-100 m, the average radiation dose received by the family members reduce by a factor of 4, wheras by increasing the house size from 75-100 m to about 120-400 m, this dose only reduce by a factor of 1.5. The average dose for family members who were at house for less than 10 hours a day is about 5 times less than that of the individuals who were at house for more than 10 hours a day. In addition, average absorbed dose by children was about 9 times more than that of spouses. On the basis of this study findings, we suggest that parameters such as the amount of received activity, type of disease, house size, presence of children at house, duration of time which family members spend with the patient at house and differences in cultural behaviors between children and their parents should be considered in order to decrease the exposure of the family members and also to decide for duration of hospitalization and the approtiate time of discharge.

Abdominal wall hernias are the most common situations requiring major surgeries. In this study, we report a large incisional hernia, as an incidental finding, in a Tc-DTPA scan of a renal transplant recepient. Increased flow of activity in dynamic phase and relatively increased and nonuniform tracer accumulation in static phase of the study were observed