COMPUTER-ASSISTED EVALUATION OF DIPYRIDAMOLE TL-201 SPECT IN PATIENTSWITH AORTIC-STENOSIS

Dipyridamole SPECT detects significant coronary artery disease (CAD) i n patients without aortic stenosis. This study was done to establish n ormal Tl-201 distribution limits in patients with aortic stenosis and to apply these normal limits to patients with aortic stenosis and angi ographically significant CAD (greater than or equal to 75% area reduct ion). Methods: Fifty-two patients (mean age 68 yr; mean valve area 0.6 7 cm(2)) were examined with Tl-201 SPECT after dipyridamole infusion ( 0.56 mg/kg during 4 min). After tomographic reconstruction, basal, mid -ventricular and apical short-axis slices were selected. The highest a ctivity in each six-degree segment was normalized to the maximal activ ity of each slice. Results: Significant CAD was found in 24 patients. Five patients without CAD, but with localized hypokinesia or left bund le-branch block, were excluded from the reference group which finally consisted of 16 patients. Sensitivity for CAD was 88% when the lowest relative activity in each segment was used as the lower limit of norma l. With -2 s.d. and -2.5 s.d. curves the sensitivity was 83% and 75%, respectively. Gender-specific limits were not used. Nonsignificant CAD was found in seven patients (<75% stenoses). Conclusions: This study presents the normal distribution of Tl-201 uptake for patients with ao rtic stenosis, using dipyridamole SPECT. The range method had the high est sensitivity for detection of significant CAD.