Role of radionuclide scintigraphy in the detection of parathyroid adenoma.

BACKGROUND: Preoperative detection of parathyroid adenoma is a diagnostic challenge. The sonography and computerized tomography (CT) scan demonstrate high sensitivity but low specificity. The advent of radionuclide scanning technique has enhanced the specificity in this context. AIM: We undertook a study to assess the role of radionuclide scanning in suspected cases of parathyroid adenomas. MATERIALS AND METHODS: Totally 28 cases were incorporated in the study. The suspicion was raised either due to raised PTH levels or recurrent calcinosis. Most of these patients had estimation of calcium done as a routine or specific investigation. The parathyroid scan was performed using either of the two techniques - Dual isotope subtraction or Sestamibi washout technique. We also used the recent approach of fusion imaging (CT + tomographic nuclear images) in selected cases. RESULTS: There were 16 true positive, 10 true negative, 1 false negative and 1 equivocal scan findings. The findings were compared with sonography, CT Scan and PTH values. The true positive yield in our study was 57%, true negative 35% and the overall sensitivity and specificity was found to be 94% and 100% respectively. CONCLUSION: We conclude that parathyroid scintigraphy is a reliable and sensitive technique in the preoperative detection of parathyroid adenomas and should be the first choice of imaging modality in suspicion of parathyroid adenoma.

Prognostic value of 99mTc-Sestamibi stress Myocardial Perfusion Single Photon Emission Computed Tomography (SPECT) in ischemic heart disease.

AIM: To study prognostic value of 99mTc-Sestamibi stress Myocardial Perfusion Single Photon Emission Computed Tomography (SPECT) in suspected or diagnosed ischemic heart disease, in an urban Indian population. METHODS: Eight hundred and eighty one patients with clinically suspected or diagnosed ischemic heart disease who underwent 99mTc-MIBI stress-rest Myocardial Perfusion SPECT (MPS) between 1st February 2001 to October 2002 were followed up for 14 +/- 2 months after the scan by questionnaire and telephonic interview with queries about cardiac death, myocardial infarct (hard events) and admission for unstable angina, CABG and PTCA (soft events). Patients were classified into pre-test: low, intermediate or high risk subsets based on clinical risk factors and ECG criteria. They were then reclassified based on MPS scan into post-test: high, intermediate and low risk subsets. Subsequent cardiac event rate was compared in the three subsets. A 12-lead ECG was an integral component of the stress MPS evaluation. RESULTS: MPS changed (1) the pre-test low risk category in 114 out of 613 patients to intermediate and 102 to high risk; (2) pre-test intermediate risk in 110 patients out of 163 to low risk and 19 patients to high risk (3) pre-test high risk category in 56 patients out of 105 to low risk and 28 to intermediate risk (total change 429 out of 881 patients). The hard cardiac event rate at one year was less than 0.5% in low risk, 2.3% in intermediate risk and 4.2% in high risk group. CONCLUSIONS: 99mTc-Sestamibi stress SPECT MPS thus provided incremental information for prognostic evaluation of patients with suspected or diagnosed coronary artery disease by assessing the effect of ischemic burden on LV function. This incremental information is crucial since coronary arteriography alone is not enough for prognosis and management decisions. Patients with a normal or low risk MPS have generally a benign prognosis with a low annual hard cardiac event rate of 0.5%. Future challenge is to identify high risk subsets within this group, with CT coronary calcium score > or = 100 and inflammation markers such as high hsCRP so that more aggressive secondary preventive measures can be instituted to prevent future hard cardiac events.

The correlation of Tc-99m MIBI scintigraphy and histological response in determining the percentage of tumor necrosis in osteosarcoma after preoperative chemotherapy.

PURPOSE: The most important prognostic factor of osteosarcoma is the percentage of tumor necrosis. Only well trained and experienced musculoskeletal pathologists can count and assess the percentage of tumor necrosis from the resected specimens. The purpose of the present study was to characterize the correlation of Tc-99m MIBI scintigraphy for assessing the percentage of tumor necrosis using postoperative histology as a gold standard. MATERIAL AND METHOD: During September 2002 to August 2004, nine consecutive patients with the diagnosis of conventional osteosarcoma were included in the present study. The osteosarcoma protocol comprises 3 courses of doxorubicin and cisplatin preoperatively followed by wide resection of tumors and another 3 courses of postoperative chemotherapy. The Tc-99m MIBI scintigraphy examination was carried out before commencing chemotherapy and after completing preoperative chemotherapy. The tumor uptake was measured using the tumor to the background ratio (TBR). Comparison of TBR before and after preoperative chemotherapy was used to calculate the alteration ratio which was reported in terms of percentage. All of the resected specimens were sent to the pathological department. The histological assessment of the response to chemotherapy was performed using the standard technique according to the current practice of osteosarcoma from the Mayo Clinic. The percentages of tumor necrosis from histology were also reported. RESULTS: The analysis of the correlation between the reduction of tracer uptake and the postoperative histological response was performed. The correlation and linear regression analysis showed that the two methods had a significant correlation (R = 0.75) regression coefficient (1.172) with p = 0.020 and 0.043, respectively. CONCLUSION: The present study showed that Tc-99m MIBI scintigraphy had a significant correlation with percentage of tumor necrosis from histology. This technique can be used to predict the response of osteosarcoma after preoperative chemotherapy.

Apical hypertrophic cardiomyopathy with apical necrosis and aneurysm formation.

Apical hypertrophic cardiomyopathy, characterized by giant T-waves and spade-shaped left ventricular cavity is prevalent in Oriental people, particularly the Japanese. We report an asymptomatic case of apical hypertrophic cardiomyopathy progressing to myocardial necrosis and aneurysm formation because of the chronic myocardial ischemia at the apex.

Adenosine myocardial SPECT--its efficacy and safety and correlation with coronary angiogram.

OBJECTIVE: The aim of this study was to determine the safety and efficacy of adenosine Tc99m sestamibi myocardial perfusion study under controlled conditions and to correlate the adenosine Tc99m sestamibi perfusion defects and the coronary angiography in patients investigated for coronary artery disease. METHODS: This prospective study included 122 consecutive patients who underwent adenosine Tc99m sestamibi single photon emission computed tomography (SPECT) myocardial perfusion study. Seventy two patients had coronary angiographic correlation. All the patients who were referred by the cardiologists for stress myocardial perfusion scan who could not be stressed physiologically for one reason or the other were included in the study. RESULTS: Among the coronary angiography group the overall sensitivity, specificity, positive predictive value and negative predictive value of adenosine Tc99m sestamibi single photon emission computed tomography myocardial perfusion study for detecting significant coronary obstruction (diameter > or = 50%) were 94.4%, 79%, 85% and 92% respectively. The side effects were transient and required no treatment. CONCLUSION: We conclude adenosine Tc99m sestamibi single photon emission computed tomogram myocardial perfusion study is a reliable test with high sensitivity and specificity for the detection of coronary artery disease.

Treadmill ECG test combined with myocardial perfusion imaging for evaluation of coronary artery disease: analysis of 340 cases.

AIM: Using Coronary arteriogram as the gold standard, stress ECG (Treadmill Test - TMT) has a sensitivity of 68% and specificity (77%) for the detection of coronary artery disease (CAD). Stress myocardial perfusion imaging (MPI) with Tc-99m Sestamibi gated SPECT has a sensitivity of 85% and specificity of 90%. The aim of the study was to ascertain if the combined use of the two physiologic tests will raise the predictive value for the presence or absence of physiologically significant CAD to 100%. METHODS AND MATERIAL: Three hundred and fourty patients (200 with suspected and 140 proved CAD) were studied with the same day rest and stress protocol. A rest MPI image was acquired with 8 mCi Tc-99m Sestamibi, followed by TMT; at the peak exercise 20 mCi tracer was injected and post-stress MPI image was acquired after 1 hour. 12-lead ECG at rest and during stress and recovery period was analyzed. RESULTS: Out of 200 patients with a prior probability of CAD 40-50% (151 with pain in chest, 81 with shortness of breath on exertion and 68 asymptomatic high risk for CAD--more than 5/9 risk factors), a normal stress MPI result in 150 patients excluded the probability of physiologically significant CAD. Fifty patients with abnormal stress MPI were refered for coronary arteriography. Stress ECG had 17% "false negative" and 23% "false positive" compared to stress MPI. In this group out of 140 known CAD, (56 post-infarct, 52 post-CABG and 32 post-PTCA), all sent for evaluation of ischemic symptoms, MPI documented 101 infarcts (fixed defects with no wall motion and thickening), 20 of them were "silent" (with no history of previous infarct) ECG did not help in picking them up. 58/101 infarcts had only fixed defects while 43/101 were accompanied by reversible ischaemia in same or other vascular territories. Thirty nine patients showed only reversible ischaemia without any infarct. Risk stratification was possible based on the extent and severity of the perfusion defects and number of territories in which defects were seen, rest LVEF, size of LV and transient dilation CONCLUSIONS: Combined stress ECG and stress MPI perform "gate keeper" function for referral for angiography, as well as for risk stratification of those who already have coronary angiograms. Decisions for revascularization should be based on combined evaluation--a shift from stenosis- based to ischaemic--based evaluation. Success or failure of revascularization was also documented by this evaluation.

Scintimammography (SMM) in breast cancer patients.

The author retrospectively reviewed the scintimammography (SMM) using 201Tl and/or 99mTc-MIBI in 45 breast cancer patients. 36 cases with 37 intact breast masses and another 9 cases with previous excision of the masses were studied. The sensitivity for the detection of the primary breast cancer was 92 per cent and that of ipsilateral axillary lymph node metastasis was only 48 per cent. SMM is helpful for the diagnosis of breast cancer and differentiating malignant from benign masses, thus improving the accuracy of routine mammography. In postoperative cases SMM is helpful to detect palpable local tumor recurrence and axillary node metastasis but it is not accurate enough for assessing the extent of microscopic tumor involvement locally and also distant metastasis. Thus, it is not recommended to use SMM alone for staging of breast cancer.