A new scanning method for thallium-201 myocardial SPECT: semidecubital position method.

The authors have developed a new scanning method for Tl-201 myocardial SPECT using a rotating gamma camera with 180-degree data collection. This requires a new type of imaging table on which the patient is placed in a 50-degree right semidecubital position to allow close proximity to the camera-collimator system. Using this method, attenuation by the imaging table is completely avoidable because the projected views in the left oblique directions are not obstructed by the table. In addition, the radius of camera rotation is about 25% shorter than in the conventional method. Phantom and 16 clinical studies were performed to compare the performance of conventional and semidecubital position methods. In phantom studies, tomographic images produced using the new method showed better lesion contrast and more counts in the posteroinferior wall of the heart than those produced using the conventional method. Clinically, 12 of the 16 studies showed more counts in the posteroinferior wall of the heart with the semidecubital position method than with the conventional method. The semidecubital position method is useful for Tl-201 myocardial SPECT, especially for evaluation of posteroinferior wall hypoperfusion.