Maria Ierardi

99mTc SESTAMIBI Scintigraphic Evaluation of Skeletal Muscle Disease in Patients with Systemic Sclerosis: Diagnostic Reliability and Comparison with Cardiac Function and Perfusion

The diagnosis of skeletal muscle involvement in patients with systemic sclerosis (SSc) is usually based on clinical, laboratory, electromyographic, and bioptic evidence of muscle disorder, whereas SSc cardiac disease is well established by nuclear medicine techniques (radionuclide ventriculography and myocardial scintigraphy). Previous reports have retrospectively hypothesized a possible relationship between cardiac and muscle involvement in scleroderma patients. In order to improve overall diagnostic accuracy in the qualitative/quantitative assess ment of skeletal muscle involvement in these patients and to compare these results with those obtained at the cardiac level, diethylenetriaminepentaacetic acid (DTPA)-99mTc radionuclide ventriculography and 99mTc SESTAMIBI myocardial and muscular scinti graphic examinations were performed in 10 SSc patients and in five healthy subjects. Muscular radioactivity, as assessed at thigh and calf levels by means of a segmental score, was significantly decreased in SSc patients in comparison with healthy subjects (global score value 15.6 ±2.2 vs 22.7 ± 1.6, p < 0.001), as well as right ventricular ejection fraction (RVEF, 34.3% ±5.3 vs 53.6% ±4.2, p<0.001) and myocardial segmental perfusion (global score value, 19.6 ± 2 vs 25.9 ± 1.1, p < 0.01 ) . The results show a high frequency of skeletal muscle involvement in patients with SSc. Moreover, scleroderma patients with muscle disorders, as evidenced by scintigraphy, show a comparable occurrence of cardiac involvement, even in the absence of clinical signs of cardiac dysfunction.

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 sarcolemma of the muscle fiber, is the cause of Duchenne type muscular dystrophy. Plasma membrane damage of the muscular fiber occurs, followed by Ca++ influx into the fibers. There is severe mitochondrial damage in dystrophic but still viable fibers. Five children aged 5-7 years were studied with MRI, TI-201, and Tc-99m sestamibi scintigraphy of the thighs. These three methods showed that the sartorius is the least damaged muscle in Duchenne type muscular dystrophy. MRI showed mild damage of adductors and quadriceps; TI-201 scintigraphy showed a marked reduction of radioactivity in the same muscles; Tc-99m sestamibi uptake occurred only in the sartorius muscle; the quadriceps was not imaged and adductors showed a faint image. A decrease of water in muscular fibers as well as fatty fibrous substitution, occurs after death of the fibers, whereas plasma membrane and mitochondrial damage reduced the uptake of tracers when the fiber is still viable. The interesting mismatch between sestamibi and TI-201 can be explained by considering that the cellular mechanism of uptake and retention of Tc-99m sestamibi involves both plasma membrane and mitochondria, whereas the uptake of TI-201 is only affected by plasma membrane damage.

Reliability of visual and quantitative hepatobiliary scintigraphy in the follow-up of patients who have undergone cholecystectomy and transduodenal sphincteroplasty

A noninvasive scintigraphic technique to assess the efficacy of a surgical procedure (e.g., cholecystectomy and transduodenal sphincteroplasty) depends on the development of reliable and accurate qualitative or quantitative diagnostic criteria that allow early recognition of the occurrence and site of complications. For this purpose, the authors divided biliary flow into a four-step progression process and analyzed transit times from the peripheral vein to the gallbladder, common bile duct, and duodenum and the transit time from the common bile duct to the duodenum. These quantitative parameters were assessed in nine healthy volunteers and 31 asymptomatic patients who had previous cholecystectomy to validate their reliability. The results indicate that the four-step Tc-99m HIDA progression analysis provides a reliable, noninvasive evaluation of biliary flow, so that it can be applied to patients who have had cholecystectomy.

Dipyridamole Technetium-99M Sestamibi Imaging in the Diagnosis of Syndrome X

In a middle-aged woman with anginal chest pain and a normal-appearing angiogram, dypiridamole technetium-99m Sestamibi scintigraphy, a noninvasive method, provided the diagnosis of syndrome X and was used in follow-up to monitor the course of disease.