Objectives. Regional myocardial blood how (MDF) and flow reserve measurements using nitrogen-13 (N-13) ammonia positron emission tomography (PET) were compared with quantitative coronary angiography to determine their utility in the detection of significant coronary artery disease (CAD).Background. Dynamic PET protocols using N-13 ammonia allow regional quantification of MBE and flow reserve. To establish the diagnostic performance of this method, the sensitivity and specificity must be known for varying decision thresholds.Methods. MBF and flow reserve for three coronary territories were determined in 20 normal subjects and 31 patients with angiographically documented CBD by means of dynamic PET and a three-compartment model far N-13 ammonia kinetics. Ten normal subjects defined the normal mean and SD of MBF and flow reserve, and 10 normal subjects were compared with patients. PET flow obtained in the territory with the most severe stenosis in each patient mas correlated with the angiographic assessment of the stenosis (severity greater than or equal to 50%, greater than or equal to 70%, greater than or equal to 90%). Receiver operating characteristic (ROC) curve analysis was performed for 1.5, 2.01 2.5, 3.0 and 4.0 SD of how abnormalities.Results. MBF and flow reserve values from the normal subjects and from territories with documented stenoses greater than or equal to 50% were significantly different (p < 0.051). A significant difference was found between normal subjects and angiographically normal territories of patients with CAD, High diagnostic accuracy and sensitivity, with moderately high specificity, were demonstrated for detection of all stenoses.Conclusions. Quantification of myocardial perfusion using dynamic PET and N-13 ammonia provides a high performance level for the detection and localization of CAD). The specificity of dynamic PET was excellent in patients with a low likelihood of CAD, whereas an abnormal flow reserve in angiographically normal territories was postulated to represent early functional abnormalities of vascular reactivity. (C) 1998 by the American College of Cardiology.

Objectives. The aim of this study was to evaluate patients with coronary artery disease to 1) determine the relation between flow reserve measured by nitrogen-13 (N-13) ammonia kinetic modeling and stenosis severity assessed by quantitative angiography, and 2) examine whether how reserve is impaired in regions supplied by vessels without significant angiographic disease.Background. With the advent of new therapeutic approaches for coronary disease, an accurate noninvasive approach for absolute quantification of how and flow reserve is needed to evaluate functional severity and extent of atherosclerosis. Nitrogen-13 ammonia kinetic modeling may permit such evaluation.Methods. Twenty-seven subjects were classified into three groups: group 1 = 5 young volunteers; group 2 = 7 middle-aged volunteers; and group 3 = 15 patients with coronary artery disease. Dynamic N-13 ammonia positron emission tomographic imaging was performed at rest and during adenosine infusion. A three-compartment model was fit to regional N-13 ammonia kinetic data to determine myocardial flow. Group 3 patients underwent quantitative coronary angiography.Results. The regional blood flow results in patients with coronary disease were classified into four subgroups: no significant detectable disease and mild (50% to 69.9% area stenosis),ate (70% to 94.9% area stenosis) or severe (95% to 100% area stenosis) coronary disease. Flow reserve was 2.95 +/- 0.65; 2.09 +/- 0.47; 2.02 +/- 0.51; 13 +/- 0.32, respectively (p less than or equal to 0.01 except mild vs. moderate). Flow reserve was correlated with percent area stenosis (r = -0.56) and minimal lumen diameter (r = 0.75). In volunteers (groups 1 and 2), flow reserves were greater than in segments without detectable disease in group 3 patients (4.10 +/- 0.71 and 3.79 +/- 0.42, respectively, vs. 2.88 +/- 0.56, p less than or equal to 0.02).Conclusions. The functional severity of coronary disease measured by N-13 ammonia positron emission tomography varied for a given stenosis but was significantly related to angiographic severity. Among patients with coronary disease, myocardial regions without significant angiographic stenoses displayed reduced how reserve than did regions in control subjects, indicating that vascular reactivity was more diffusely impaired in group 3 than was suggested by angiography. Noninvasive quantification of myocardial how reserve using dynamic N-13 ammonia positron emission tomography yields important functional data that permit definition of the extent of disease even when disease is not apparent by angiography.

Positron emission tomography (PET), in combination with myocardial blood flow tracers, allows highly accurate diagnosis of coronary artery disease using visual data interpretation. To increase the objectivity of data analysis and to reduce interobserver variability, we developed an automated analysis method for the three-dimensional definition of myocardial activity, which includes true volumetric data extraction and mathematical constraints of activity sampling to the expected shape of the left ventricle. Data are displayed in a standardized polar map or three-dimensional format for comparison with a normal database. The first clinical evaluation of this method in 52 patients using receiver operating characteristics (ROC) curve analysis demonstrated high diagnostic accuracy for detection as well as localization of coronary artery stenosis in predefined vascular territories. The interobserver and intraobserver agreement for localization of disease was excellent, with correlation coefficients varying from 0.85 to 0.99 for individual vascular territories. Thus, this automated quantitative analysis program provides highly accurate and reproducible evaluation of cardiac PET flow studies. Definite determination of its diagnostic accuracy requires a prospective multicenter trial in a larger patient population employing the criteria for abnormality established in this initial clinical evaluation.