Advanced visualization's impact on imaging

This month brings, of course, a wealth of reports from the Radiological Society of North America (RSNA) annual convention. Journal studies also noted several developments on the advanced visualization front.

Following are a few highlights:

Lung cancer screening: Reginald Munden, MD, MBA, of MD Anderson Cancer Center in Houston, discussed the National Lung Screening Trial (NLST). Lung cancer screening differs from other organized screening initiatives, Munden said, because findings have to be managed differently. Hence, learning from the experiences (and mis-steps) of early adopters is essential.

“I can’t emphasize enough the need for a multidisciplinary team,” Munden said. This team should include a radiologist, primary care physician, surgeon, pulmonologist, prevention physician, oncologist and radiation oncologist. Other key players include a physicist to answer questions about radiation; a coordinator to serve as the face of the screening program, meet patients and answer their questions; a marketing representative; and a patient advocate.

One of the first steps to establishing a screening program is to establish guidelines regarding who will be screened and how often. MD Anderson initially used guidelines a bit broader than NLST, but reverted to NLST recommendations as the data apply to those criteria.

Munden recommended standardized reporting and developing and maintaining a good database to lay the groundwork for future research to improve lung cancer screening in practice.

Cardiac CT: Cardiac CT is a dose reduction success story, according to James P. Earls, MD, of Fairfax Radiological Consultants in Fairfax, Va. As cardiac CT technology has advanced, the amount of dose has increased. He cited the PROECTION I study, published in 2007, which recorded a mean dose of 12 mSv for cardiac CT angiography exams. The researchers also concluded that the dose range was too variable among various scanners and that dose reduction protocols were underutilized.

Dose reduction is a multi-pronged strategy. “Putting all of the pieces together can reduce dose 90 percent,” Earls said.

Prostate cancer detection: As researchers and radiologists explore various advantages and disadvantages of T2-weighted MR imaging and functional MR, multiparametric MR has demonstrated its utility in the detection, localization and characterization of prostate cancer. However, the technique requires a high level of radiologist experience and is prone to observer variability.

Thomas Hambrock, MBChB, from the department of radiology at Radboud University Medical Centre in Nijmegen, the Netherlands, and colleagues designed a study to evaluate the effect of CAD on reader performance in the differentiation of benign from malignant prostate lesions at 3T multiparametric MR imaging.

Six less-experienced radiologists who had interpreted fewer than 50 prostate MR exams and four experienced radiologists who had read more than 100 prostate MR exams reviewed multiparametric 3T MR data for 34 prostate cancer patients. Images were first read without CAD and then reviewed with CAD software. Radiologists received CAD training prior to the study.

Radiologists were provided with predefined regions of interest (ROI) and estimated the likelihood of malignancy on a scale from 0 to 100 percent for each ROI. Then the ROI CAD likelihood was displayed and the readers entered an additional likelihood of malignancy with CAD.

Without CAD, the less-experienced radiologists had an overall area under the curve (AUC) of 0.81. AUC was 0.86 for the peripheral zone and 0.72 for the transition zone. Experienced readers had an overall AUC of 0.88 without CAD, with AUCs of 0.91 and 0.81, respectively, for the peripheral zone and transition zone.

The addition of CAD resulted in significant improvements in lesion discrimination for less experienced readers, and allowed this group to achieve performance on par with experienced radiologists.

Overall AUC rose to 0.91 for less-experienced readers with the addition of CAD. AUC increased to 0.95 in the peripheral.

Improvements in detection and treatment require a robust IT infrastructure. Is your facility prepared for the latest advances in advanced visualization?

Beth Walsh, editor

bwalsh@trimedmedia.com