Use of the selective linogram in cardiac tomography quality control

Quality control for detection of patient motion is essential in tomographic myocardial imaging. Despite significant limitations, the summation image or conventional "linogram" has long been advocated as a useful image in the detection of vertical motion. In this study a new quality control image entitled the "selective linogram" is proposed to replace the summation image in routine cardiac single-photon emission cardiac tomography (SPECT) quality control. The selective linogram is constructed in a manner somewhat analogous to the sinogram. In the sinogram, each row represents a different projection angle; in the selective linogram each column represents a different projection angle.

After selection of eight motion-free studies from acquisitions at our clinical center, vertical motion of various types (bounces, shifts, and creep) were added to the projection frames. Summation image and selective linogram quality control images from these motion-containing studies and the original motion-free studies were presented in a blinded manner to two observers for scoring of patient motion. The selective linogram was significantly more accurate in allowing detection of vertical motion than was the summation image (accuracy 89% vs 47%).

The selective linogram image is markedly superior to the summation image for the detection of vertical patient motion during cardiac SPECT. This new technique can be a valuable aid in SPECT quality control.