[99mTc-DMSA [V]] in detection of metastases of medullary thyroid carcinoma

Medullary thyroid carcinoma [MTC] is a rare thyroid cancer secreting calcitonin [CT] which is the most sensitive and specific tumor marker for MTC. This type of thyroid cancer is able to metastasize to different body areas including regional lymph nodes, lungs, liver and bone. The aim of this study was to assess the sensitivity and specificity of [99mTc-DMSA [V]] whole body scan [WBS] in detection of metastases in MTC. This descriptive and prospective study was performed in 15 patients with MTC referred to our nuclear medicine centre since 2004 to 2005. These patients were compared regarding age, sex, and duration of the disease. Sensitivity and specificity of each diagnostic modality in detection of metastases were calculated and compared statistically. [99mTc-DMSA [V]] showed 91% sensitivity and 75% specificity as compared with serum calcitonin as gold standard. The figures for CT scan were 82% and 45%, respectively. CEA showed 64% sensitivity and 50% specificity. It is concluded that despite the slightly lower sensitivity and specificity of [99mTc-DMSA [V]] as compared to calcitonin [Gold-standard method], this radiotracer can be used for identification of recurrence or metastasis of medullary thyroid carcinoma

Usefulness of Dipyridamole Myocardial Perfusion SPECT in Patients with Left Bundle Branch Block

Diagnosis of coronary artery disease [CAD] in patients with left bundle branch block [LBBB] is considered as a challenge in cardiology due to the low accuracy of noninvasive methods such as basal and stress electrocardiography [ECG]. This diagnostic challenge can be reduced but not eliminated using dipyridamole as a stress method instead of exercise. The aim of this study was to assess the diagnostic value of dipyridamole stress Tc-99m Sestamibi single photon emission computed tomography [SPECT] myocardial perfusion imaging in patients with complete LBBB. We studied 40 patients with permanent and complete LBBB using Tc-99m Sestamibi SPECT and dipyridamole stress to evaluate CAD. Perfusion defect was considered fixed when there was no difference between rest and stress score, while reversible defect was defined as a segment with higher score on stress images. All patients underwent coronary angiography. Eleven patients [27.5%] had normal myocardial perfusion SPECT and 29 patients [72.5%] had reversible perfusion defects. Angiography was positive in 30 patients, while 10 cases showed normal angiography. The sensitivity, specificity, positive predict value and negative predict value of our study for detecting >50% coronary stenosis was 86.6%, 70%, 89% and 64% respectively. We found 33 [82.5%] patients with concordant angiography and myocardial perfusion SPECT results [p=0.002]. Angiography was positive in 90% of patients with reversible perfusion defects on myocardial perfusion SPECT. In summary, Tc-99m Sestamibi SPECT in patients with LBBB showed high accuracy [82.5%] in detecting >50% coronary stenosis