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), facio-scapulo-humeral (FSH), limb-girdle (LG) and myotonic (MT) dystrophy. 1. 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. 2. 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. 3. There was a significant correlation between %FIB and the L/M ratio (r = 0.79, p < 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 < 0.05). 4. ECT showed marked LV dilatation in seven (15 %), apical aneurysm in five (11 %) and vertical heart in 12 (26 %) of the 47 patients. 5. There were no significant correlations between age or clinical stage scores and numbers of defect segments or %FIB in each group. 6. 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. 7. Thallium-201 planar imaging and standard 12-lead ECG underestimated the perfusion defects which were evaluated with ECT. (author)