CT installed base can handle demand for colon cancer screening

A University of Wisconsin study has found that U.S. hospitals and outpatient clinics have enough excess multislice CT capacity to handle an expected increase in demand for CT screening colonography without adding new equipment.

Thousands of CT scanners are used daily for a wide range of medical applications. Results of large clinical trials have validated the addition of CT colonography to the list, while the American Cancer Society has just endorsed it as the test of choice for colon cancer screening.

Showing CTC's value for colon cancer screening was one thing. Proving it could handle the volume of patients who might need the test in the next decade or so, however, is an entirely different matter.

Although the impact of introducing CTC colorectal cancer screening at the national level upon available MSCT units remains unknown, calculations suggest they might be sufficient to handle the task, said study coauthor Dr. David H. Kim, an assistant professor of abdominal imaging at the University of Wisconsin - Madison.

Kim and colleagues used mathematical probability models to determine the average number of CTC scans per day that would be needed to do screening based on the number of scanners available nationwide. They included only MSCT scanners based on the premise that single-detector units were inadequate to perform CTC, Kim said.

Based on their baseline analysis, a total of 37,227,541 eligible adults would need to undergo CTC screening over a 10-year period. Minding the appropriate variables for subject age and screening intervals, they estimated CTC screenings should go at a rate of about one to 1.5 studies per unit daily.

Kim presented his group's results at the 2008 ARRS meeting in Washington, DC.

According to IMV market research 2006 benchmark report estimates, slightly more than 10,000 scanners are operating in the U.S. More than two-thirds are MSCT units, and only about 10% of these are doing CTC studies, he said.

Estimates indicate nearly 300,000 people would be screened for colon cancer with CTC in year one alone. The models also calculated MSCT market penetrance, going from 10% in year one to about 70% by the end of the 10-year cycle. The model projects the increase based on the number of people positively influenced by CTC screening results.

Another interesting study finding, Kim said, is that of all the several possible variables that can come into play, none would have a significant impact on final outcomes. Even by assuming compliance rates near 90%, each MSCT scanner available in the country would not have to produce more than two studies per day. Current compliance rates for breast cancer screening approach 75%.

The calculation models make conservative assumptions and probably underestimate true MSCT scanner capacity in the U.S., Kim said, but he warned the study did not address staffing, training, or geographic variables.

"CT capacity seems more than adequate to support CTC screening," he said.

For more information from the Diagnostic Imaging archives:

CT colonography CAD trial could quicken regulatory approval

CT colonography experts assess new screening guidelines

Combined 3D 'filet' and 2D axial views may prove optimal for CT colonography

Positive results strengthen case for CT colonography screening