MRI first-pass myocardial perfusion in patients undergoing percutaneous laser revascularization

Purpose: Evaluation of MRI first-pass myocardial perfusion pre- and post-percutaneous myocardial laser revascularisation (PMR). Patients and Methods: MRI was performed in 10 patients with coronary heart disease grade III-IV, 1-4 days prior to PMR, as well as 1-5 days and 6 months after PMR. Contrast enhanced (0.1 ml/kgBw; 4 ml/s) 'first-pass' MRI imaging was obtained by breathhold, ECG-triggered, multislice Turbo-FLASH GRE. For quantitative analysis the absolute and percentual signal-to-noise (S/N)-measurements were calculated. Positron emmission tomography (PET) was regarded as the gold standard for myocardial perfusion. Results: The mean values of absolute and % S/N increase revealed no statistical difference between pre- and immediately post-PMR imaging. 6 months following PMR both values were significantly elevated (14.1 vs. 24.4 and 127 vs. 176; p=0.03 and p=0.01). However, the non-treated myocardial segments revealed a similar S/N pattern. Intraindividual analysis showed a significant S/N increase post PMR in one patient, and in additional 4 patients 6 months later. PET revealed increased myocardial perfusion in only two patients. Following PMR 5/10 patients experienced a significant reduction of chest pain equivalent to two CCS grades. Two of these had significant S/N elevations but no evidence of increased perfusion by PET. Conclusion: S/N first-pass calculations following PMR do not correlate well with the true situation of myocardial perfusion. They seem to be more closely associated with other histological phenomena and possible explanations for the improved clinical symptomatology. (orig.)