MUSCULAR UPTAKE OF TC-99M MIBI AND TL-201 IN DUCHENNE MUSCULAR-DYSTROPHY

Lack of dystrophin, a protein localized to the inner surface of the sa rcolemma of the muscle fiber, is the cause of Duchenne type muscular d ystrophy, Plasma membrane damage of the muscular fiber occurs, followe d by Ca++ influx into the fibers, There is severe mitochondrial damage in dystrophic but still viable fibers, Five children aged 5-7 years w ere studied with MRI, TI-201, and Tc-99m sestamibi scintigraphy of the thighs, These three methods showed that the sartorius is the least da maged muscle in Duchenne type muscular dystrophy, MRI showed mild dama ge of adductors and quadriceps; TI-201 scintigraphy showed a marked re duction of radioactivity in the same muscles; Tc-99m sestamibi uptake occurred only in the sartorius muscle; the quadriceps was not imaged a nd adductors showed a faint image, A decrease of water in muscular fib ers as well as fatty fibrous substitution, occurs after death of the f ibers, whereas plasma membrane and mitochondria[ damage reduced the up take of tracers when the fiber is still viable. The interesting mismat ch between sestamibi and TI-201 can be explained by considering that t he cellular mechanism of uptake and retention of Tc-99m sestamibi invo lves both plasma membrane and mitochondria, whereas the uptake of TI-2 01 is only affected by plasma membrane damage.