PACS provokes increase in incidental findings

While the introduction of PACS into radiology practice may increase productivity, it also appears to be associated with an increase in reported incidental findings and recommended follow-up studies, according to a new report (Radiology 2002;225(2):500-505).

Incidental findings are a long-standing concern of radiologists, who must balance the potential benefit of discovering an unexpected and perhaps important disease process against raising patient anxiety and the costs associated with investigating the findings.

This dilemma has become particularly challenging with the advent of PACS. The inclusion of localizer images and uncropped images means more information is potentially available for interpretation, said lead author Dr. Steven C. Wagner, a radiologist at Thomas Jefferson University Hospital in Philadelphia.

The study sought to evaluate the effect of PACS on incidental findings outside the area of interest and the clinical implications of follow-up, focusing on lumbar spine MRI.

Wagner reviewed a total of 2500 reports of lumbar spine MR examinations performed at 1.5T. These included 500 consecutive lumbar spine reports of each year over a five-year period:

?one year prior to PACS implementation
?one year during transition from hard copy to PACS
?three years following PACS introduction

Wagner then tabulated the incidental findings outside the area of interest cited in the reports. He noted frequencies, the organ system involved, and recommendations, plotting this data as well as estimated costs based on Medicare reimbursements. Follow-up studies were reviewed as well.

The number of incidental findings increased from 19 before PACS to 31 during transition and to 53, 49, and 50 in the years subsequent to PACS implementation, resulting in a maximum increase of 179%. The increase was statistically significant during each post-PACS year.

"The most common incidental findings involved potential renal, pelvic, hepatic, pulmonary, and lymph node abnormalities," Wagner said.

The total number of recommended follow-up studies increased from five before PACS to 15 during transition and 32, 22, and 18 after PACS implementation, with a maximum increase of as much as 540%. Recommended ultrasonographic studies increased the most, from two in the pre-PACS year to 11 during transition and 27, 17, and 14 in the three post-PACS years.

Follow-up expense increased by a mean of 146% after PACS implementation from $4221 per 1000 studies in the pre-PACS year to $9307, $13,426, $10,558, and $8252 thereafter. Of the 202 incidental findings, four represented occult malignancy, with an attendant expense of $5721 per diagnosis.

"This is a preliminary study and it is not transposable to all clinical settings, since different MRI vendors have different localizer sequences," said Dr. William Morrison, an associate professor of radiology at Thomas Jefferson.

Also, different body parts will have different results, he said. The foot, for example, is not surrounded by other organs and may have no additional findings on a localizer sequence compared with the lumbar spine, which has many nearby structures.

"What we can do as radiologists is work with the vendors to make sequences that account for the increase in incidental findings," Morrison said.

Vendors could make a really low signal-to-noise sequence that shows only gross anatomy or a really good sequence so that radiologists can properly evaluate all of the adjacent organs present, he said.

"Otherwise, we could work with DICOM to prevent these localizer sequences from becoming a part of the permanent record," Morrison said.