Rosanna Tavolaro

99Tcm-sestamibi scintimammography in patients with suspicious breast lesions : Comparison of SPET and planar images in the detection of primary tumours and axillary lymph node involvement

Planar scintimammography with 99Tcm-sestamibi (99Tcm-MIBI) has been shown to be useful in diagnosing breast carcinoma. The aim of this study was to compare single photon emission tomography (SPET) and planar imaging for scintimammography with 99Tcm-MIBI in the detection of primary breast cancer and axillary lymph node involvement. Sixty-three females with mammographically suspicious lesions and 12 controls were evaluated. Dynamic images were acquired commencing immediately after the injection of the radiopharmaceutical, followed by multiple planar images in the supine and prone positions plus SPET supine imaging. A final histopathological diagnosis was achieved after surgery. A total of 66 breast lesions were considered. No focal uptake of 99Tcm-MIBI was observed in the breasts or axillas of the controls. In the patients with breast cancer, the sensitivity was 92.9% (39/42) for SPET, 71.4% (30/42) for supine and 85.7% (36/42) for prone planar imaging, respectively; the specificity was 87.5% for SPET and 91.6% for the planar scans. Metastatic axillary lymph node involvement was seen in 19 patients: the sensitivity was 84.2% (16/19) for SPET and 63.2% (12/19) for planar images; the specificity was 91.3% and 95.7%) respectively. Our results confirm the high diagnostic accuracy of 99Tcm scintimammography in the diagnosis of breast cancer, and suggest that SPET is more sensitive than planar images, especially in detecting axillary lymph node involvement.

Acute oral trimetazidine administration increases resting technetium 99m sestamibi uptake in hibernating myocardium

BackgroundTrimetazidine is an antiischemic drug protecting the myocardium from ischemic damage through the preservation of mitochondrial oxidative metabolism, without any hemodynamic effect. 99mTc-sestamibi is accumulated by myocytes according to mitochondrial function. As mitochondrial metabolism is thought to be present in hibernating myocardium, the aim of the study was to investigate trimetazidine effects on infarcted and eventually hibernating myocardial areas by means of 99mTc-sestamibi perfusional scintigraphy, comparing them to postoperative recovery of wall motion.Methods and ResultsTwelve patients with previous myocardial infarction underwent 2 perfusion imaging tomographic studies at rest with 99mTc-sestamibi, receiving placebo or trimetazidine (60 mg orally), and subsequently underwent revascularization procedures. An echocardiographic study was carried out before and >3 months after revascularization. At polar map analysis of placebo scan, infarcted vascular territories (wall motion score index: 2.65±0.31) showed 73.7%±10.4% of the territory with activity <2.5 SD from the mean of normals, for a severity (expressed as the sum of the standard deviations below average normal values in all abnormal pixels) of 833.8±345.7. Polar map analysis of the trimetazidine scan showed tracer uptake increased significantly in 11 of them, by 8.2%±3.0% (p<0.001) and by 180.3±111.0 SD (p<0.001), respectively. Postoperative wall motion score index improved significantly in 9 of these territories (−0.9±0.4, p<0.001).ConclusionsTrimetazidine-associated increase in 99mTc-sestamibi uptake in infarcted but viable myocardial areas is probably related to an improvement in mitochondrial oxidative metabolism that is essential to 99mTc-sestamibi retention. Additionally, coupling trimetazidine administration to 99mTc-sestamibi perfusional scintigraphy may represent a means of detecting viable myocardium.

Technetium-99m sestamibi myocardial tomography based on dipyridamole echocardiography testing in hypertensive patients with chest pain.

The non-invasive diagnosis of coronary artery disease in hypertensives with chest pain is an important clinical concern because all exercise-dependent tests display limited feasibility and diagnostic accuracy; by contrast, dipyridamole echocardiography testing has been shown to have a similar feasibility and accuracy in hypertensive and normotensive subjects. The aim of this study was to evaluate the diagnostic capability of technetium-99m sestamibi tomography based on dipyridamole echocardiography testing in hypertensives with chest pain, and to compare the scintigraphic results with those of coronary angiography, exercise electrocardiography and dipyridamole echocardiography. Forty subjects with mild to moderate hypertension, chest pain and no previous myocardial infarction were submitted to99mTc-sestamibi tomography (at rest and after high-dose dipyridamole echocardiography) and to exercise electrocardiography testing. At coronary angiography 22 patients (group A) had significant epicardial coronary artery disease (≥70% stenosis of at least one major vessel) and 18 normal main coronary vessels (group B). Dipyridamole99mTc-sestamibi imaging was positive in 21/22 patients of group A and in 5/18 of group B. Dipyridamole echocardiography was positive in 18/22 patients of group A and in 5/18 of group B. Exercise electrocardiography was positive in 15/22 patients of group A and in 11/18 of group B. Four out of five subjects in group B with positive results in all the tests showed a slow run-off of angiographic contrast medium, probably due to small-vessel disease. Significant epicardial coronary artery disease in hypertensives with chest pain is unlikely when dipyridamole99mTc-sestamibi tomography is negative. When scintigraphy is positive, either epicardial coronary artery disease or a small-vessel disease condition is possible. The association of scintigraphy with dipyridamole echocardiography testing allows the assessment of contractile function and myocardial perfusion by a single pharmacological stress.

Myocardial Scintigraphy with 99mTc-Sestamibi in Children with Kawasaki Disease

Kawasaki disease (KD) is a systemic vasculitis syndrome of early childhood. It involves particularly the coronary arteries and may cause aneurysms and thrombotic occlusions. Echocardiography is the most useful method of detecting coronary aneurysms. Nevertheless, obstructive lesions are difficult to evaluate and often need invasive coronary angiography. An important feature of this disease is the possibility of finding coronary pathology several years after the onset. This characteristic makes KD an important cause of coronary artery disease (CAD) in young adults. Thus patients with KD and previously diseased coronary arteries should be kept under long-term control. However, coronary angiography is invasive and cannot be performed repeatedly, espe cially in young patients. As an alternative, thallium 201 scintigraphy has been employed, but its low-energy photons are suboptimal for standard gamma-camera imaging, particularly in children aged less than three years. To verify the usefulness of a noninvasive assessment of myocardial perfusion, the authors used rest and dipyridamole 99mTc-Sestamibi scan in 15 children (ranging from one to six years of age) with Kawasakis cardiac involvement. Coronary aneurysms have been demonstrated by echocardiography in 12 patients; 8 patients were also submitted to cardiac catheterization. The sensitivity of 99mTc-Sestamibi imaging for detection of overall coronary lesions was 88% and the specificity was 93%. These data suggest that rest/dipyridamole 99mTc-Sestamibi scintigraphy is an accurate and noninvasive method for the detection and follow-up of Kawasakis cardiac damage even in patients aged one year.

Tc-99m tetrofosmin accumulation in lung cancer and its metastases.

Tc-99m tetrofosmin is a new myocardial-perfusion imaging agent that also has been used in the detection of various tumors. In this case, Tc-99m tetrofosmin imaging was performed in a patient with adenocarcinoma of the left lung. Increased uptake was observed in the primary tumor site and in its metastatic lesions (right mediastinal lymph nodes and brain). The primary tumor and its brain metastasis had been previously detected by chest x-ray and CT. Mediastinal lymph node involvement was later confirmed by mediastinoscopy. These findings suggest a possible role for Tc-99m tetrofosmin as a non-invasive method to evaluate patients with lung cancer.

Radioisotope assessment of heart damage in hypertransfused thalassaemic patients

Twenty-five thalassaemic patients treated with repeated blood transfusion (BT) and intensive iron removal therapy were studied by echocardiography and rest/stress equilibrium gated radionuclide angiocardiography (EGNA). Stress left ventricular ejection fraction (LVEF) showed an important negative correlation with number of BTs (r = −0.75). Abnormal values of stress LVEF were measured after 200 BTs: these data demonstrate the effectiveness of stress LVEF in the follow-up of patients who have undergone repeated BTs and the clinical importance of intensive chelation therapy. Peak filling rate did not show diagnostic value in the early detection of iron cardiotoxicity. However, its inverse correlation with BT (r = −60) indicates that iron overload depresses the diastolic parameters.

Preoperative Identification of Viable Myocardium: Effectiveness of Nitroglycerine-Induced Changes in Myocardial Sestamibi Uptake

In order to predict tissue viability in infarcted myocardial areas, changes induced by nitroglycerine infusion on Sestamibi myocardial uptake were evaluated in 37 patients with previously confirmed myocardial infarction undergoing coronary artery bypass grafting, and compared with echocardiographic and perfusional changes occurring after the operation. The improvement of Sestamibi uptake after nitroglycerine correctly classified 24/26 (92%) patients showing postoperative improvement of wall motion in the infarcted area, whereas 24/31 (77%) patients with nitroglycerine-induced increase in Sestamibi uptake had improved wall motion after operation. The presence of collateral flow to the infarcted area was associated with a significantly (P < 0.01) higher increase in Sestamibi uptake both during nitroglycerine infusion and postoperatively. An increase in wall motion score after operation was associated with a significantly higher (P < 0.05) increase in Sestamibi uptake score during nitroglycerine infusion. Thus, the results of this study suggest that Sestamibi perfusional myocardial scintigraphy during nitroglycerine infusion is capable of assessing viable but chronically hypoperfused myocardium and predicting postoperative wall motion and perfusional improvement, to yield the best results in patients with evidence of collateral circulation that supplies the infarcted area.