Development and performance evaluation of the second model 256-detector row CT.

Since our initial development of the 256-detector row CT scanner (256-row CT) for four-dimensional (4D) imaging of moving organs in 2003, the results of physical performance and those in animal and human studies have suggested that this scanner may be useful in the examination of moving organs such as the heart and lungs. We have now developed a second model of the 256-row CT with improved specifications, with a scan time of 0.5 s/rotation at the highest speed and real-time reconstruction and display of dynamic 3D images (4D images). Here, we investigated the image characteristics of the new model, including spatial resolution, noise, and low-contrast detectability, as well as the dose profile and its integral in stationary phantoms. One volunteer and one patient with lung cancer were scanned, and their images were evaluated. The results show that all characteristics have been improved compared with those of the first model, with a remarkable improvement in the low-contrast detectability and slice sensitivity profile. In a contrast study, coronary arteries were clearly visualized in the normal heart without electrocardiographic gating. Movement and deformation of the tumor in the patient with lung cancer was captured in a study of a single breath cycle. The second model 256-row CT with improved characteristics may be beneficial in imaging of moving organs such as the heart and lungs, and may enable cerebral perfusion studies of the whole brain.