SPECT dipyridamole scintigraphy for detecting coronary artery disease in patients with isolated severe aortic stenosis.

BACKGROUND: The sensitivity and specificity of non-invasive methods--specifically single-photon emission computed tomography (SPECT) dipyridamole-thallium myocardial perfusion--for detecting coronary artery disease (CAD) in patients with severe aortic stenosis remains unclear. Occasionally, these patients present with atypical angina. Therefore, a CAD diagnosis must be excluded to prevent unnecessary cardiac catheterization. METHODS: To determine the diagnostic value of SPECT dipyridamole-thallium imaging in this population, we compared the effectiveness of the imaging procedure with that of coronary angiography by prospectively analyzing patients who underwent both procedures. Group 1 included 59 patients who were asymptomatic or had atypical angina; group 2; 51 preoperative aged-matched patients with typical angina. SPECT acquisition was performed 15 min after 0.142 mg/kg/min of dipyridamole infusion completion, and redistribution images were performed 4 h after thallium injection. Two cut-off values of luminal diameter narrowing, >50 and >70%, defined significant CAD. RESULTS: Coronary angiography with significant CAD (>50%) was present in 15 (25%) group 1 patients and in 16 (32%) group 2 patients (P=NS). The sensitivity was greater in group 2 than in group 1 (56 versus 26%; P=0.001). The specificity, positive and negative predictive value, and accuracy in the groups were similar. CAD of >70% luminal stenosis was present in 11 (19%) group 1 patients and in 12 (23%) group 2 patients (P=NS). The positive predictive value was greater in group 2 than in group 1 (75 versus 43%; P=0.001) but similar sensitivity, specificity, negative predictive value, and accuracy. The likelihood ratio for abnormal test increased in patients with CAD of >70%. CONCLUSIONS: symptoms of typical angina had significant impact on test sensitivity, positive predictive value and likelihood ratio for abnormal test. Furthermore, SPECT dipyridamole-thallium imaging was a useful non-invasive method to exclude the diagnosis of significant CAD (high specificity) in asymptomatic and symptomatic patients with isolated severe aortic stenosis.

[Mapping with Technetium-99 methoxy-isobutyl isonitrile at the bedside after coronary thrombolysis]. / Mapeamento com metoxi-isobutil-isonitrila marcada com tecnécio99 à beira do leito após trombólise coronária.

PURPOSE: To evaluate the feasibility of bedside Technetium99-methoxy-isobutyl-isonitrile (99mTc-MIBI) cardiac imaging to assess perfusion after thrombolytic therapy (TT) for myocardial infarction (MI). METHODS: We studied 9 patients (mean age 59 +/- 9 years) submitted to TT with 100 mg of rt-PA in 90 minutes within the 6 hours of the onset of MI with subsequent angiography. 99mTc-MIBI was injected intravenously in a doses of 740 MBq immediately before TT start. Imaging was performed in three moments: study 1--as soon as the TT finished, study 2--3-18 hours after TT; study 3--7-10 days after TT. A perfusion score was established in each study and then compared to determine the perfusion patterns after TT. We compared through linear regression, the perfusion score with left ventricle ejection fraction, and with CKMB enzymatic peak. RESULTS: All patients had a patent infarct related artery. The perfusion score of study 1 varied from 12 to 22, mean 15.8 +/- 3.7, and correlated with ejection fraction (r = 0.9, p < 0.01) and peak CKMB (r = 0.78, p = 0.03). Four (44%) patients presented perfusion score improvement in study 2 (varied from 12 to 23, mean 16.8 +/- 4.3) and 8 (88%) in study 3 (varied from 12 to 28, mean 19.0 +/- 4.3). CONCLUSION: Bedside 99mTc-MIBI cardiac imaging is useful to quantify myocardial area under risk before TT, and to identify the late (7 to 10 days) benefit of TT.

Radioisotopic assessment of peripheral and cardiac muscle involvement and dysfunction in polymyositis/dermatomyositis.

99mTc-pyrophosphate musculoskeletal imaging and 99mTc-red blood cell gated blood pool imaging were performed on 10 patients with documented polymyositis/dermatomyositis. Abnormal 99mTc-pyrophosphate uptake by peripheral muscles was found in 8 patients (6 mild, 2 marked). Cardiac uptake occurred in 5 patients and was 3+ in 2 with cardiovascular symptoms. These 2 patients also had abnormal EF on gated blood pool imaging. Patients without myocardial 99mTc-pyrophosphate uptake had normal EF. Patients with myocardial 99mTc-pyrophosphate uptake had abnormal wall motion, in proportion to the degree of uptake. Response to therapy and outcome were poorer in patients with marked scintigraphic changes. These findings suggest that the magnitude of 99mTc-pyrophosphate myocardial uptake may have prognostic implications in these patients.

Quantification of ocular inflammation with technetium-99m glucoheptonate.

Histological and morphometric evaluation of ocular inflammation is difficult, particularly when there is extensive ocular involvement with abscess formation and necrosis. A quantitative imaging procedure applicable to humans would be important clinically. To establish such a procedure, turpentine-induced ocular inflammation was obtained by subconjunctival injection in the right eye of 55 rabbits. The left eye was used as control and injected with a volume of saline equal to the volume of turpentine in the right eye. Volumes of turpentine or saline were 0.02, 0.04, 0.06, 0.2 and 0.6 ml, and the rabbits were divided into groups 1-5, according to these volumes. Imaging was performed 48 h after turpentine injection and 6 h after intravenous injection of 10 mCi of technetium-99m glucoheptonate (99mTc-GH). An inflammatory reaction index (IRI), defined as the ratio of counts of the right eye divided by counts of the left eye, was used. IRIs were proportional to the degree of inflammation and allowed the distinction of 3 subgroups: one represented by group 4, one by group 5 and one by groups 1, 2 and 3. This method of quantification of ocular inflammatory processes using 99mTc-GH is original, rapid, non-invasive, reproducible and safe, although unable to differentiate inflammatory processes caused by doses of turpentine which are very small and close to each other. It is conceivable that its application to humans will bring new insight into the ocular inflammatory process and response to therapy.

Pulmonary clearance of technetium 99m diethylene triamine penta-acetic acid aerosol in patients with amiodarone pneumonitis.

Amiodarone pneumonitis is a serious complication that may lead to fatal lung fibrosis. In an attempt to diagnose this condition as early as possible, the technetium-99m-labelled diethylene triamine penta-acetic acid (99mTc-DTPA) aerosol washout rates of 10 non-smoking normal volunteers (group 1), 10 non-smoking patients on a long-term amiodarone regimen with dilated cardiomyopathy but no congestive heart failure (group II) and 10 patients with amiodarone pneumonitis (group III) were compared. Spirometric measurements, as percentage predicted, were higher in group I than in group III (P less than 0.05). The global mean effective half-lives of 99mTc-DTPA aerosol for both lungs together in minutes were 65 +/- 14, 55 +/- 16 and 27 +/- 4 for groups I, II and III, respectively. Group III values were significantly lower than those of groups I and II (P less than 0.05). Our results demonstrated that amiodarone pneumonitis alters the alveolar-capillary membrane permeability to hydrophilic molecules. The pulmonary clearance of 99mTc-DTPA aerosol is a useful test in the differentiation of patients on a long-term amiodarone regimen without side effects from patients with amiodarone pneumonitis. The test is rapid, easy to perform and has the potential for playing an important role in deciding which patients should discontinue therapy.

Gallium-67 imaging in human heart transplantation: correlation with endomyocardial biopsy.

Endomyocardial biopsy seems to be the most accurate method to use for diagnosis and follow-up of acute rejection of the transplanted heart. This investigation compared a noninvasive procedure, gallium-67 imaging, with endomyocardial biopsy in the detection of acute rejection in heart transplantation. Seven male patients (aged 41 to 54 years) sequentially had 46 gallium-67 scintigrams and 46 endomyocardial biopsies between 1 week and 8 months after transplantation. Both studies were obtained in the same day, 48 hours after the administration of an intravenous injection of gallium-67 citrate. Cardiac uptake was graded as negative, mild, moderate, and marked according to an increasing count ratio with rib and sternal uptakes. Histologic findings were graded as negative, mild acute rejection, moderate acute rejection, severe acute rejection, resolving rejection, and nonspecific reaction. Negative biopsies were not found with moderate uptake, and neither moderate nor severe acute rejection were found with negative scintigrams. Imaging sensitivity was 83% with 17% false negatives and 9% false positives. Of seven studies with moderate uptake, five showed moderate acute rejection, and the patients had specific therapy with a decline in uptake, which correlated with resolving rejection. It is conceivable that in the future this technique may be used as a screening procedure for sequential endomyocardial biopsies in the follow-up of heart transplant patients.