256-slice CT creates 4D liver studies

Researchers in Japan have tested a prototype 256-slice CT scanner in human patients, according to a study in the July issue of the American Journal of Roentgenology. The technology enabled dynamic imaging of liver cancer in real-time.

Imagers have been able to perform contrast-enhanced 3D imaging of the liver's arterial phase using 16-slice CT scanners, albeit with limitations. Current MSCT detector technology would not be able to obtain more than one image per second of a descending contrast agent bolus.

Dr. Shinichiro Mori and colleagues from research institutions in Chiba and Osaka used an experimental MSCT scanner in three randomly selected patients with hepatocellular carcinomas. They were able to detect all lesions using dynamic contrast enhancement in an almost simultaneous volumetric imaging cine mode.

Dynamic 256-slice CT obtained continuous 3D coronal renderings 30 seconds after contrast injection. The hepatic veins, abdominal aorta, and renal arteries were best visualized at 30, 34, and 36 seconds after injection, respectively. The technique also allowed observation of the backflow of contrast material to the inferior vena cava in one patient experiencing heart failure.

Investigators applied an imaging protocol including the following parameters:

• 912 transverse x 256 craniocaudal detectors

• one-second rotation time, 10-sec total scanning time

• 256 x 0.5-mm beam collimation

• 120 kV, 200 mA, and an effective dose of 27.7 mSv/10 sec

• 90 mL iopamidol injection at 3.5 mL/sec

The 256-slice scanner allowed superior cine imaging reconstructions of structures with a craniocaudal distance of approximately 10 cm in any plane with several postprocessing techniques including full-volume renderings and maximum intensity projections.

The system can cover one or more organs during one phase of contrast enhancement. It could also produce functional studies of the head, liver, and renal and coronary arteries, investigators noted in the study.

For more information from the Diagnostic Imaging archives:

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Why stop at 16? CT imagers predict 256-row scanners