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9. Gould KL, Goldstein RA. Mullani NA, et al. Noninvasive assessment of coronary stenoses by myocardial perfusion imaging during pharmacologie coronary vasodilation. VIII. Clinical feasibility of positron cardiac imaging without a cyclotron using generator-produced rubidium-82. J Am Coll Cardio/ 1986:7:775-789. 10. Demer LL, Gould KL, Goldstein RA. et al. Assessment of coronary artery disease severity by positron emission tomography. Comparison with quantitative arteriography in 193 patients. Circulation 1989:79:825-835. 11. Goldstein RA. Kirkeeide RL. Small mg RW. et al. Changes in myocardial perfusion reserve after PTCA: noninvasive assessment with positron tomography. J NucÃ-Med 1987:28:1262-1267. 12. Go RT, Marwick TH. Maclntyre WJ, et al. A prospective comparison of rubidium-82 PET and thallium-201 SPECT myocardial perfusion imaging utilizing a single dipyridamole stress in the diagnosis of coronary artery disease. J NucÃ-Med 1990;31: 1899-1905. 13. Stewart RE, Schwaiger M, Molina E, et al. Comparison of rubidium-82 positron emission tomography and thallium-201 SPECT imaging for detection of coronary artery disease. Am J Cordial 1991:67:1303-1310. 14. Herrero P. Markham J. Shelton ME, Bergmann SR. Implementation and evaluation of a two-compartment model for quantification of myocardial perfusion with rubidium-82 and positron emission tomography. Circ Res 1992:70:496-507. 15. Green MA, Mathias CJ. Welch MJ. et al. Copper-62-labeled pyruvaldehyde bis(N4-

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Technetium-99m-Sestamibi SPECT to Detect Restenosis after Successful Percutaneous Coronary Angioplasty Elisa Milan, Orazio Zoccarato, Arturo Terzi, Federica Ettori, Omelia Leonzi, Luigi Niccoli and Raffaele Giubbini Nuclear Medicine and Cardiology Departments, Civic Hospital and University of Brescia, Brescia; and Nuclear Medicine Department. Fondazione ClÃ-nicadel Lavoro- Veruno, Lavoro- Veruno, Italy This study evaluated the accuracy of ""Tc SPECT in predicting restenosis after primary successful PTCA. Methods: Thirty-seven patients with equivocal symptom-limited exercise stress testing were evaluated. All patients underwent separate day exercise-rest 99mTc-sestamibi SPECT. The perfusion studies were evaluated using three different methods of analysis: visual inspection, semiquantitative and quantitative polar map analysis. The perfusion studies were interpreted in absence of a pre-PTCA scan. All patients underwent a control coronary angiography within 1 mo. Results: Sensitivity and specificity of ""Tc-sestamibi SPECT in predicting restenosis were 87.5-78%, 50-65% and 75-74% for visual inspec tion, semiquantitative and quantitative polar map analysis, respec tively. Sensitivity and specificity related to the vascular territories Received July 10, 1995; revision accepted Oct. 8, 1995. For correspondence or reprints contact: Bisa Milan, MD, Nuclear Medicine Depart ment, Civic Hospital, Piazza Spedali Civili, 1, 25100 Brescia, Italy.

1300

were: LAD territory 93-73% (qualitative analysis), 53-60% (semiquantitative analysis), 80-67% (quantitative analysis); LCX territory 83-100% (qualitative analysis); and 33-100% (semiquantitative analysis), 67-100% (quantitative analysis); and RCA territory 67-80% (qualitative analysis), 67-60% (semiquantitative analysis), 67-80% (quantitative analysis). Conclusion: These data suggest that 99nTcsestamibi SPECT is a useful noninvasive tool in the follow-up evaluation of patients who have undergone angiographically suc cessful coronary angioplasty even in the absence of a pre-PTCA perfusion study. Key Words: angioplasty; restenosis;technetium-99m-sestamibi J NucÃ-Med 1996; 37:1300-1305

Uespite the immediate efficacy of percutaneous transluminal coronary angioplasty (PTCA), its long-term efficacy is limited by the presence of restenosis reported in approximately 30% to

THEJOURNAL OFNUCLEAR MEDICINE • Vol. 37 • No. 8 • August 1996

45% of patients who have undergone the procedure (1-3). The increase in balloon angioplasty with application to more com plex situations has led to a justified increase in the likelihood of restenosis. Restenosis is reported to be a time-related phenomenon, having a peak incidence between 2 and 3 mo after the procedure (4,5). However, in several cases restenosis can be observed later and, moreover, the progression of CAD in previously normal vessels is unpredictable. The capability to predict this phenomenon on the basis of clinical and procedural parameters remains limited. In the era of multivessel PTCA and partial revascularization, the ability to localize ischemia noninvasively is crucial to patient care. These findings have generated an increasing interest in the use of myocardial perfusion studies to detect myocardial ischemia in the myocardial territory supplied by the restenosed vessel in both symptomatic and asymptomatic patients (6-11). Scintigraphic studies performed before and after PTCA (10,11 ) have been demonstrated to be effective in predicting restenosis. However, a crucial point is that pre-PTCA scintigraphic studies are rarely available and studies must be read without knowledge of the pre-PTCA myocardial perfusion pattern. The aim of the present study was the evaluation of the diagnostic accuracy of myocardial SPECT with 99mTc-sestamibi to predict restenosis in a group of patients, with no pre-PTCA perfusion study, referred to our laboratory for equivocal exercise stress test (asymptomatic patients with positive exercise ECG, pa tients with atypical angina or without angina and positive or nondiagnostic exercise ECG, patients with typical angina and negative exercise ECG) after successful PTCA.

FIGURE 1. Seventeen-segment SPECT model used for "Tc

bull's eye

SPECT analysis. Segments 1, 2, 3,12,13,14,15,16 and 17 were attributed to the LAD territory; segments 4, 5, 6 and 7 to the LCX territory; and segments 8, 9, 10 and 11 to the CDX.

breath or severe angina, 2 mm or more downsloping or horizontal ST depression, hypotension or complex ventricular arrhythmias. At peak exercise 99mTc-sestamibi was injected and the patient was asked to continue exercising for an additional 2 min. Technetium-99m-Sestamibi

SPECT Acquisition

and Processing

The stress and rest studies were performed on two different days using 1100 MBq of 99mTc-sestamibi each. Image acquisition METHODS started 60-90 min after the injection and followed a light meal. SPECT imaging was performed on a LFOV gamma-camera com Patients Thirty-seven consecutive patients (33 men, 4 women; aged 55 ± puter system fitted with a high-resolution collimator (FWHM = 7 11 yr) with equivocal exercise stress test after successful PTCA for mm). Beginning from the right anterior oblique to the left posterior oblique, 60 projections over a 180°circular orbit, in a step-andchronic stable angina pectoris due to single or multiple coronary shoot mode, were obtained using a 20% energy window centered artery disease (CAD) were studied. on the 140-keV photopeak. Images were stored on a 64 X 64 Seventeen patients had a history of previous (>6 mo) myocar matrix, with a 1.3 zoom factor. One-pixel thick transaxial sections dial infarction (12 Q-wave and 5 non-Q-wave myocardial infarc tion) in the region of the diseased coronary artery, none were were reconstructed after correction for flood dishomogeneity, by treated by aortocoronary bypass graft surgery (CABG) and all of filtered backprojection (10 mm Wiener filter). From transaxial them had a positive exercise test for myocardial ischemia before slices, 16-mm thick slices of short, vertical and horizontal long PTCA. The PTCA procedure was considered successful when the axes were reconstructed. From 3-mm thick short-axis slices, polar residual stenosis was less than 50% in diameter with a good runoff maps were obtained. and filling of the distal vessel on angiography. Analysis of Technetium-99m-Sestamibi SPECT All the patients had equivocal exercise stress test after PTCA Qualitative Analysis. For purposes of visual interpretation, stress and therefore received a follow-up 99nTc-sestamibi SPECT fol and rest tomograms were evaluated by consensus of two observers lowed by a coronary angiography within 1 mo. Coronary angiog (RG, EM) aware of the patient history. raphy was interpreted visually without knowledge of the noninvaSevere reversible perfusion defects were considered a marker of sive test results. restenosis. Finally the scans were read as normal or abnormal in the Twenty-eight left anterior descending (LAD), 10 left circumflex territory supposed to be perfused by the vessel treated by PTCA. (LCX) and 12 right coronary (RCA) were analyzed. The time Semiquantitative Analysis. Stress and rest polar maps were interval between PTCA and 99mTc-sestamibi SPECT ranged from 1 to 30 mo (10.2 ±7.7). The clinical definition of restenosis was evaluated in a different reading session by two observers (RG, EM) using a 17-segment model. Both readers were unaware of patient indicated by an increase in the stenosis diameter of the dilated history and qualitative analysis results. Each segment was assessed lesion above 50% of the initial value. using a four-point scoring system (0 = normal, 1 = slightly reduced uptake, 2 = severely reduced uptake, 3 = absence of Exercise Stress Testing Bicycle exercise testing was performed during the drug washout uptake). period. All patients underwent multistage-symptom limited-exer Disagreement regarding the classification of segments into cise testing after an overnight fast. A 12-lead electrocardiogram normal, abnormal, reversible perfusion defect or fixed defect was and blood pressure were recorded every 3 min. The exercise work observed in 7), determined by a receiver operating characteristic (ROC) curve, was found to discriminate best between patients with and without restenosis. Out of 47 territories analyzed, 24 (51%) were found to have a reversible 29.62± perfusion defect >7% ischemie, of these 18 (75%) vessels had 22.14±16.09± an angiographie documented restenosis; 17 of 23 (74%) terri tories with A score