Complementary roles of scintigraphic and angiographic techniques in assessment of the extent of coronary artery disease

The use of computer-assisted diagnosis in cardiac-perfusion nuclear medicine studies: a review

The use of computer-assisted diagnosis has become widespread in cardiac nuclear medicine. Quantitative programs are commercially available for ventriculography, phase analysis, and thallium 201 perfusion studies. The goal of these programs is to eliminate interobserver variability by objectively analyzing the studies without causing a loss of accuracy. In addition, by using quantitative data not apparent on visual inspection, some programs attempt to increase sensitivity for disease above that possible by the visual reading of images. Programs that analyze perfusion studies to detect coronary artery disease have received the most interest. Results have varied, but sensitivities as high as 95% have been reported. This review discusses the techniques of computer-assisted diagnosis for thallium 201 myocardial-perfusion studies. The circumferential and washout profile methods are discussed in detail.

Comparative accuracy of clinical tests for diagnosis and prognosis of coronary artery disease

The discriminant accuracy of 14 variables derived from clinical evaluation, cardiac fluoroscopy, exercise electrocardiography, thallium scintigraphy and radionuclide angiography was assessed with respect to the diagnosis of angiographic coronary artery disease (CAD) among 607 patients undergoing coronary angiography, and with respect to the prognosis of subsequent cardiac death or nonfatal infarction among 4,104 patients followed for 1 year after testing. Discriminant accuracy (quantified in terms of the area under a receiver-operating characteristic curve for each variable) ranged from 50 to 73% for diagnosis, and from 54 to 77% for prognosis. Although there was a great deal of variability from test to test, variables representing direct or indirect manifestations of myocardial ischemia tended to correlate better with prognosis. Thus, variables derived from radionuclide angiography and thallium scintigraphy tended to have more prognostic accuracy than diagnostic accuracy, while fluoroscopy tended to have more diagnostic accuracy than prognostic accuracy. The pattern associated with clinical evaluation and exercise electrocardiography was less discernable. Accordingly, the accuracy of noninvasive tests with respect to diagnosis and prognosis of CAD should be separately determined based on individual empiric observation.

Should the intent of testing influence its interpretation?

A test is often interpreted as "normal" or "abnormal" by a single criterion, regardless of the intent of testing. The discriminate accuracy of this convention was critically analyzed using information content (I), likelihood ratio and the area under the receiver-operating characteristic curve. Three ejection fraction variables were assessed--ejection fraction at rest, exercise ejection fraction and the change in ejection fraction from rest to exercise--each relative to three intentional goals: diagnosis of coronary artery disease in 929 patients without previous myocardial infarction, prediction of multivessel disease in these same 929 patients and prediction of multivessel disease in 507 patients with previous myocardial infarction. The information content of exercise ejection fraction (IEX) was higher than for ejection fraction at rest (IR) or for the change from rest to exercise (IEX-R), and was relatively constant regardless of the goal of testing. In contrast, neither IR nor IEX-R was constant. IR was lowest for diagnosis of coronary artery disease, whereas IEX-R was highest for this same goal. These empiric observations are consistent with the quantitative relation predicted by information theory: IEX = IR + IEX-R. Thus, ejection fraction at rest has little discriminate value relative to the diagnosis of coronary artery disease, but does have value in evaluating the extent of disease in patients after myocardial infarction. Exercise ejection fraction and change in ejection fraction are nearly equally useful for purposes of diagnosis, whereas the former is most useful for functional evaluation in postinfarction patients.(ABSTRACT TRUNCATED AT 250 WORDS)

The declining specificity of exercise radionuclide ventriculography

Although exercise radionuclide ventriculography was initially reported to be a highly specific test for coronary-artery disease, later studies reported a high false-positive rate. To verify this turnabout, we analyzed the responses in 77 angiographically normal patients; 32 were studied from 1978 to 1979 (the early period), and 45 from 1980 to 1982 (the recent period). Most patients studied in the early period had normal responses (94 per cent for ejection fraction and 84 per cent for wall motion). In contrast, normal responses were less frequent in patients studied in the recent period (49 per cent for ejection fraction and 36 per cent for wall motion, P less than 0.001). The probability of coronary disease before testing was higher in these patients (38 vs. 7 per cent, P less than 0.001). More patients studied in the recent period underwent radionuclide ventriculography before angiography (78 vs. 22 per cent, P less than 0.001), and more of these prior studies had abnormal results than those performed after angiography (55 vs. 6 per cent, P less than 0.0001). Thus, two factors are responsible for the temporal decline in specificity: a change in the population being tested (pretest referral bias) and a preferential selection of patients with a positive test response for coronary angiography (post-test referral bias).