[Transmyocardial laser revascularization--the initial experiences of imaging in MRT]

Imaging of myocardial signal alteration and perfusion differences after transmyocardial laser revascularization (TMLR).

5 patients suffering from coronary vessel disease underwent MRI (0.5 T) pre- and 4-7 d post-TMLR. T1-weighted spin echo sequences were acquired ECG-triggered native and after injection of gadolinium. Qualitative analysis was performed on both native and contrast-enhanced images. Myocardial signal alterations and wall changes were evaluated. Qualitative and quantitative analyses of contrast-enhanced images were performed with regard of post-therapeutic perfusion differences. Analysis was based on contrast-to-noise (C/N) data obtained from operator defined "regions of interest".

Visualization of laser-induced channels was not possible. Native scans obtained before and after TMLR revealed no significant change with regard to the qualitative analysis. Both qualitative and quantitative analyses demonstrated a posttherapeutic increase of C/N in both the left ventricular myocardium (64.4 pre-TMLR; 89.1 post-TMLR; p = 0.06) and the septum in the majority of cases. No significant difference between laser-treated left myocardium and untreated septum was observed (p > 0.05).

Single myocardial laser channels could not be visualized with a 0.5-T MRI. However, visualization of increased myocardial contrast enhancement in laser-treated left ventricular myocardium was evident in the majority of cases on the basis of qualitative and quantitative analyses.

The MRI technique used enabled a first, limited depiction of TMLR-induced myocardial changes. The clinical value and impact still have to be defined.