QUANTITATIVE MEASUREMENTS OF CARDIAC PHOSPHORUS METABOLITES IN CORONARY-ARTERY DISEASE BY P-31 MAGNETIC-RESONANCE SPECTROSCOPY

Background P-31 metabolite measurements in the human heart by magnetic resonance spectroscopy (MRS) have been reported previously. By use of a method in which metabolite content was quantified with reference to a standard located outside the chest, it has become possible to measu re the content of phosphocreatine (PCr) and ATP in vivo in the human h eart. In this study, PCr and ATP contents were measured by P-31 MRS an d compared in human myocardium with reversible ischemia or scar diagno sed by exercise thallium scintigraphy. Methods and Results Forty-one s ubjects with stenosis of the left anterior descending coronary artery (>50%) and 11 healthy control subjects (C) composed the present study group. Patients were divided into two groups on the basis of exercise Tl-201 scintigraphy: a reversible Tl-201 defect group (RD[+], n=29) wh o demonstrated redistribution at late image and a fixed Tl-201 defect group (RD[-], n=12). While the subjects lay supine within the magnet, P-31 MR spectra were obtained from the anterior and apical regions of the left ventricle by slice-selected one-dimensional chemical shift im aging. For metabolite quantification, a standard was placed at the cen ter of the surface coil. ANOVA revealed significant differences among the three groups with respect to the mean (+/-SD) PCr at rest (C, 12.1 4+/-4.25 >RD[+], 7.64+/-3.00 >RD[-], 3.94+/-2.21 mu mol/g wet heart ti ssue, P<.05) as well as a significant decrease in ATP in the RD(-) gro up (C, 7.72+/-2.97; RD[+], 6.35+/-3.17 >RD[-], 4.35+/-1.52 mu mol/g we t heart tissue, P<.05). Conclusions Compared with healthy control subj ects, PCr content decreased significantly in patients with both revers ible and fixed Tl-201 defects, and ATP content decreased significantly in subjects with fixed thallium defects. These results suggest that t he measurement of ATP content in the human heart by P-31 MRS is a clin ically important method for the evaluation of myocardial viability.