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Nuclear magnetic resonance (NMR) imaging has been shown to accurately portray cardiac anatomy and function. To investigate the potential of NMR imaging for the assessment of coronary stenosis in patients with chest pain, ultrafast NMR imaging in conjunction with a T1 (longitudinal relaxation time) contrast agent was performed in 17 patients with chest pain who had undergone cardiac catheterization. These included 12 patients with significant coronary artery stenoses and 4 who underwent repeat NMR study after myocardial revascularization. Cardiac images at rest were obtained during rapid intravenous injection of gadolinium-DTPA (0.04 mM/kg). Electrocardiographic-gated images were acquired over 380 ms, with repetitive images obtained every 3 to 4 s. After contrast injection, there was pronounced signal enhancement in the right ventricular cavity, followed by enhancement in the left ventricular cavity and myocardium. Regional myocardium perfused by a diseased vessel demonstrated a lower peak signal intensity (p = 0.001) and lower rate of signal increase (p = 0.001) than did myocardium perfused by coronary arteries without stenosis. Repeat NMR study after revascularization showed an increase in peak signal intensity (p less than 0.002). These results demonstrate the clinical potential of dynamic gadolinium-DTPA-enhanced NMR imaging for the assessment of coronary artery disease in patients with chest pain. In combination with anatomic and functional NMR imaging, this technique has the potential to provide a comprehensive noninvasive cardiac evaluation of patients with suspected coronary artery disease.

Subjective estimates of the angiographic severity of coronary artery stenoses show variability and inaccuracy. We therefore tested the accuracy of a newly developed computerized image analysis system for quantitating vessel diameter from cineangiograms. Fourteen cylindrical phantoms of known diameter were filled with contrast medium and filmed over a wide range of clinically relevant radiographic conditions in order to develop regression equations that related computer-derived to anatomic diameters. Computer measurements of vessel diameter were unaffected by vessel size, magnification, focal spot size, thickness of scattering medium, kilovolt peak, or location within the radiographic field, but a correction factor was necessary for a small but significant (p < .01) linear dependence on contrast medium concentration. The accuracy of computerized vessel diameter measurements ranged between + 59 and 137 ,u for all conditions except for rapid vessel motion and contrast medium concentrations of 50% or less meglumine diatrizoate (Renografin 76), both of which resulted in reduced accuracy as well as in the inability to locate lumen edges of vessels less than 1 mm in diameter.Circulation 68, No. 2, 453-461, 1983. SUBJECTIVE VISUAL ESTIMATES of percent stenosis of a coronary artery from cineangiograms have been shown to be characterized by a large interobserver variabilityl-3 and a descrepancy between angiographic and postmortem estimates of lesion severity has been noted in a number of studies. further objectify measurements of luminal dimensions. Although the reproducibility of various objective methods of diameter measurement has been studied, the accuracy of these measurements has received little attention.The fact that radiographic vessel images have edge gradients rather than sharply demarcated edges is not widely appreciated by angiographers. 14 Accurate diameter measurement is dependent on precise localization of the anatomic vessel edge within the edge gradient, and the magnitude of error in diameter measurements associated with arbitrary assignment of the vessel edge within the edge gradient may be considerable. A new method for computerized edge detection of coronary arteries from digitized 35 mm cineangiographic images with the use of specific algorithms to locate spatially disparate points within the edge gradient has been developed. The hypothesis that each of these points can be mathematically related to the anatomic edge was tested by filming contrast mediumfilled cylindrical phantoms over a wide range of cineradiographic conditions and comparing computer-derived measurements of diameter from digitized frames with the known diameters.

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