Evaluation of a multicrystal gamma camera and rotating chair for tomographic studies of the heart

This study evaluates the feasibility of performing tomographic studies with a multicrystal gamma camera combined with a rotating chair.

Tomographic acquisitions were performed with a cardiac phantom containing eight defects of different sizes. Defect size was determined from the fraction of counts in the short-axis slices that fell below a fixed threshold value. Image contrast was determined from the ratio of minimum/maximum counts. Images of an American College of Nuclear Physicians cardiac single-photon emission computed tomographic phantom were acquired and the results were compared with those obtained from 194 centers in the United States. For cardiac studies with 201Tl and 99mTc, threshold values of 65% to 70% gave the best correlation (R2 > 0.94) between true and measured defect sizes, although the slope of the regression line was less than 0.95 for both isotopes. Small inferior defects demonstrated poor image contrast, particularly for 99mTc. Of the three defects in the American College of Nuclear Physicians phantom, the two largest were identified in the tomographic images.

A multicrystal gamma camera system coupled with a rotating chair can be used for tomographic studies of the heart. Image quality is poorer than that seen on conventional single-photon emission computed tomographic systems, particularly for 99mTc.