CT: All the possibilities

Multislice CT has radiology and cardiology abuzz. The advent of next-generation scanners at last fall's RSNA meeting brought new hopes for improved procedures old and new, namely in cardiac applications. Debuts of a variety of new units and high accolades for installs since then have kept CT high on the radar screen.

Sixteen-slice scanners are hitting a sweet spot in mapping vasculature in the liver, CT angiography and CT colonography. Coronary arteries are now being conquered for more than 90 percent of the population, according to a German study released this spring. Temporal resolution jumps 20 percent over four-slice. And on the financial side, studies such as CT colonography are finally gaining ground in reimbursement - with three payers now in Wisconsin and two new CPT codes.

New 32- and 40-slice systems bring still-higher gantry rotation speed and more impact on temporal resolution. Cardiac benefits most, since nearly every patient can be imaged. Exam times shrink as does image post-processing time to nearly immediate image review. The 40-slice system covers 40 mm per rotation at speeds of 144 mm per second, allowing for a total body scan in 10 to 15 seconds (a comfortable breath-hold for most). Better diagnoses will come from thinner slices, and thus improved spatial resolution and contrast in small regions (even without contrast), less noise and artifacts. Radiation dose is cut to 15 to 20 percent compared with 16-slice.

Three new 64-slice systems were rolled out at the 6th Annual International Symposium on Multidetector-Row CT in late June, with positive first impressions of 64-slice's ability to assist in evaluating chest pain and detecting evidence of a heart attack, pulmonary embolism and aortic dissection. Scan times of 5 to 8 seconds further conquer cardiac motion issues. Perfusion imaging has great promise, too.

But what about the massive image volume? 2,000 images produce a gigabyte of data. Workflow is changing for the technologist, too, since functions are pushed from the scanner to the workstation, making multislice CT more like PACS and more of a priority in image management.

For a closer look at the clinical and workflow angles of multislice CT, see our Special Focus section.