[Myocardial involvement in muscular dystrophy evaluated by thallium-201 emission computed tomography]

The clinical usefulness of thallium-201 myocardial emission computed tomography (ECT) for evaluating left ventricular myocardial fibrosis was assessed in 47 patients with Duchenne (MD), facioscapulo-humeral (FSH), limb-girdle (LG) and myotonic (MT) dystrophy. Trans-, long- and short-axial images were interpreted quantitatively by circumferential profile analysis, and the extent of fibrotic tissue (%FIB) was estimated by integrating hypoperfused areas in six to eight consecutive short-axial slices. Lung/mediastinum count ratio (L/M ratio), LV cavity dilatation, aneurysm formation and cardiac malrotation were also assessed with ECT. Distinct ECT defects were demonstrated in 95 of a total of 235 LV segments (40%) and in 37 of 47 cases (85% of DMD, 71% of FSH, 50% of MT and 60% of LG). They were observed specifically in the posterior wall (82%) and the apex (65%) in DMD, and were scattered in all LV wall segments in FSH, LG, and MT. There was a significant correlation between %FIB and the L/M ratio (r = 0.79, p less than 0.001), and the L/M ratio was significantly higher in DMD than in MT (0.67 +/- 0.36 vs 0.34 +/- 0.25, p less than 0.05). ECT showed marked LV dilatation in seven (15%), apical aneurysm in five (11%) and vertical heart in 12 (26%) of the 47 patients. There were no significant correlations between age or clinical stage scores and numbers of defect segments or %FIB in each group. During the one-year follow-up period of these patients, a DMD boy with the largest %FIB (54%) and the highest L/M ratio (1.4) together with LV dilatation had complications of refractory heart failure and he died eight months following the ECT examination. Thallium-201 planar imaging and standard 12-lead ECG underestimated the perfusion defects which were evaluated with ECT.