Catheter related artifacts on bone scans: report of two cases

Bone scanning using the 99mTc-phosphate analogs is an established diagnostic modality and a commonly requested radioisotope examination for a variety of pathologies involving the skeleton, such as osteomyelitis, bony metastases, and occult fractures. The bone scan is one of the most commonly requested procedure in most nuclear medicine department. The images show areas of increased and decreased activity usually related to the bone turnover. The bone scan is interpreted by evaluating the pattern of radioactive localization in the skeleton and identifying areas of increased uptake [hot spots] or, less frequently, decreased or absent activity [1]. Unfortunately, the findings are most often very nonspecific and do not tell us the exact underlying cause of the abnormal activity. A variety of factors may change the normal distribution of bone-seeking radiopharmaceuticals. Although most of the times these areas of abnormal radiotracer activities are due to true pathologic bone states, however, it is not infrequent that they are caused by technical errors such as urinary contamination, nonuniformity of gamma camera, and attenuation of activity by foreign bodies. These artifactual causes warrant careful attention to prevent unnecessary interventions. In certain conditions, nonosseous structures other than the urinary tract are seen on the bone scan. For example, there may be localized muscle uptake, such as myositis ossificans, or localization in a pleural effusion. Such serendipitous findings may constitute welcome diagnostic information [1]. On the other hand, soft-tissue uptake may at times hamper interpretation of the study by bringing in artifacts that degrade the quality of the images. Therefore, recognition of patterns of nonbony uptake is important for correct identification of artifacts and accurate interpretation of the scan [1]. This paper presents two cases of artifactual causes of odd radiotracer activity in bone scans. In both cases the artifact is at least somewhat related to an indwelling catheter

[Agreement of two methods of planar and SPECT scintigraphy with 99mTc- RBC in detection of liver Hemangioma]

Hemangiomas are the most frequent benign tumors of the liver and detecting them from metastasis or other malignant hepatic tumors is of outmost importance. 99mTc- RBC scan is highly specific and is the method of choice for this differentiation. This scintigraphy is performed in Planar and SPECT modes. These two procedures are in agreement most of the times, however since SPECT is more expensive and time consuming we planned a study to evaluate the agreement of these two methods. Sixty two patients [age range 20-80 yr, mean age 42 yr], 41 female [67%] and 20 male [33%], who were under evaluation for liver mass detected on abdominal ultrasound or CT scan, underwent 99mTc- RBC scan with both Planar and SPECT methods. The data was processed by computer and SPSS software [11.5]. Planar scan was positive in 42% and negative in 59% of cases, while for SPECT study these values were 68.9% and 31.1%, respectively. The Kappa value for planar and SPECT scan results was 48%, and there were 17 lesions [27%] which were detected only by SPECT. SPECT scan defined 35% of the posteriorly located hemangiomas, and 58.3% of hemangiomas smaller than 3 cm, which were not detected by planar scans. Also 75% of patients with multiple hepatic lesions showed more lesions by SPECT as compared to planar scan. Since there is a weak agreement between SPECT and Planar scan, SPECT is considered the more reliable method in diagnosis of liver hemangioma and this is especially true when the hemangioma is of small size, has a posterior location or in cases of multiple lesions

[Myocardial 99m Tc-MDP uptake on the bone scintigraphy in the hemodialysis-associated amyloidosis:a case report]

Amyloidosis is characterized by an abnormal extracellular deposition of amyloid in different organs, where it usually causes some type of dysfunction. Its cause is unknown. Five different types of amyloidosis have been described according to the underlying disease; immunoglobulin amyloidosis, familial amyloidosis, senile systemic amyloidosis, secondary amyloidosis and hemodialysis-associated amyloidosis. We report a case of hemodialysis-associated amyloidosis in a 56-year-old man that radionuclide imaging demonstrated intense uptake of Tc-99m MDP within the myocardium. The diagnosis of amyloidosis was established by analysis of aspirated abdominal fat, although other non- invasive modalities didn't reveal any positive findings. The first clue to the possible presence of amyloidosis in this case was provided by the radionuclide bone scan performed, which revealed intense tracer uptake in the heart suggesting amyloid deposit. We conclude that in cases of extraosseous accumulation of Tc-99 MDP especially as a diffuse pattern of myocardial uptake, a diagnosis of amyloidosis should be considered, in an appropriate clinical setting

[Evaluation of diagnostic role of 99mTc-terofosmin scintigraphy in cold thyroid nodules]

Various radiopharmaceuticals, including 67Ga, 201Tl, and 99mTc-sestamibi have been used to differentiate benign from malignant thyroid nodules. 99mTc-Tetrofosmin, a lipophilic cationic radiotracer, and 99mTc-sestamibi have also been reported to accumulate in thyroid tumors. In this study, we evaluated the role of 99mTc-Tetrofosmin in the differentiation of malignant from benign thyroid nodules. We prospectively studied 108 patients with solitary cold thyroid nodule on 99mTc-pertechnetate scintigraphy [33 malignant and 75 benign] to investigate the diagnostic value of 99mTc-Tetrofosmin scintigraphy. 99mTc-Tetrofosmin scintigraphy was performed 15, 60, and 120 minutes following IV injection of 20 mCi [740 MBq] of radiotracer in the anterior planar mode with a gamma camera equipped with LEAP collimator. The scans were visually analyzed by two experienced nuclear physician. The nodules with late tracer retention [activity more than adjacent thyroid tissue] were classified as positive and nodules without late retention were interpreted as negative for malignancy. Fine needle aspiration [FNA] was performed in all patients in 3-7 days interval. 52 patients were subsequently operated on while 56 patients refused surgery. These 56 patients, however, had at least two negative FNA results. 45 out of 108 nodules show high 99mTc-Tetrofosmin uptake on delayed images; 27 of them were malignant. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated to be 81.8%, 76.0%, 54.0%, and 90.4% respectively. Accuracy of the test was also determined to be 77.7%. We concluded that 99mTc-Tetrofosmin scintigraphy is a relatively sensitive, but not enough specific, method in diagnosing malignant thyroid nodules. This agent could be of value in the presence of FNA limitations

[Effects of treatment with radioactive iodine on gonadal functions in patients with differentiated thyroid cancer]

Background: The purpose of this study was to evaluate the effect of treatment with radioactive iodine on the function of gonads in males and females with follicular and papillary thyroid carcinoma

Materials and Methods: Consenting patients in the reproductive age were grouped according to the cumulative dose of received radioiodine and followed for at least 12 months. For all men, serum levels of FSH, LH, and testosterone were measured some [53 cases] were also studied by semen analysis. For women, tests for serum levels of LH, FSH, estrogen, and progesterone were performed

Results: Overall, 246 patients [159 females, 87 males] were studied. In 87.4% of men, there was an increase in serum FSH level after radioiodine therapy, in 20.7% of whom the level remained high during follow-up period. The average serum level of FSH after each course of treatment was significantly higher than the level before treatment [p<0.01], and there was a meaningful correlation with the cumulative dose of received iodine [p<0.001]. Reduced number of sperms was shown in 35.8% of male patients, among whom 73.7% also showed reduced motility. In 36.8% of the patients with reduced sperm number [13.2% of the total], this finding was persistent during the follow-up period. Increased level of FSH was correlated with reduced sperm counts in all doses [p<0.005]. There was no significant correlation between serum levels of LH and testosterone with iodine treatment in males [p=0.47]. In women, no significant correlation between gonadal-hypophyseal hormones and treatment with radioactive iodine was found, and there were no signs and symptoms of sexual dysfunction. Infertility was not noticed in any patient and no case of abortion was found

Conclusion: It seems that cells in spermatogonia lineage [in contrast to Leydig cells] are radiosensitive, with the sensitivity related to the cumulative dose of received radioactive iodine. But in the oogonia cell line, the radiosensitivity is insignificant

Studying the specificity of bone SPECT for differentiating malignant from benign lesions in the vertebral column of the patients with a known primary malignancy

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 8 female] 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

value of myocardial perfusion imaging in differentiating between idiopathic dilated cardiomyopathy from the ischemic form

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. 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 17 segments 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. 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. Considering excellent accuracy of myocardial perfusion scan with scoring system in discrimination of ischemic dilated cardiomyopathy from idiopathic dilated cardiomyopathy, this noninvasive test could be considered the main diagnostic test

Treatment 's results of hyperthyroid patients with iodine - 131

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. 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. 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 correction 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. 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

Quantitative evaluation of normal uptake of mandibular condyle in bone scan with Tc99m-MDP

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 and 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 and female patients were observed [P=0.26, alph=0.05]

Evaluation of the effect of various parameters on the amount of radiation dose received by family members after 131-I therapy

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 micro Sv/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

Imaging of medullary thyroid carcinoma with Tc-99m [V] DMSA

Twenty-one patients with medullary thyroid carcinoma were studied prospectively with Tc-99m [V] DMSA after surgery. Pentavalent DMSA scintigram demonstrated abnormal uptake in 13 and equivocal uptake in 6 patients. Finally, seven patients with surgical or other imaging documentation were selected for this paper. Most of these patients were asymptomatic. Six patients had hypercalcitonemia and serum calcitonine was not measured in one patient. Whole body scan with Tc-99m [V] DMSA demonstrated abnormal radiotracer uptake in all patients locating in the neck [3 cases], mediastinum [5 cases], bone [2 cases], liver [1 case] and thyroid lobes [2 cases]. This preliminary study with the locally developed Tc-99m [V] DMSA showed that it is a useful imaging agent for localization of metastatic lesions in asymptomatic patients with medullary thyroid carcinoma and high serum calcitonine

value of thyroglobulin [tg] measurement in different thyroid disorders

Thyroglobulin is a glycoprotein which is synthesized by the thyroid follicular cells. The blood level of this protein is changed in different physiologic and pathologic thyroid conditions. In this papar, the usefulness of thyroglobulin assay, methods of measurement, problems in evaluation and interpretation of the results in physiologic and disease processes are reviewed