Both CT and MRI utilization and the number of images being collected for those exams have increased significantly in recent years, according to a recent study published in Academic Radiology. The authors believe this could potentially lead to an increase in errors made by overworked radiologists.

Robert J. McDonald, MD, from the department of radiology at the Mayo Clinic in Rochester, Minn., and colleagues performed the study, examining the total number of images for every CT and MRI exam performed at their institution between 1999 and 2010.

In that timespan, over 1.5 million CT and MRI exams were performed by a radiologist. From 1999 to 2010, CT utilization increased 68%, MRI utilization increased 85%, and overall utilization increased 75%.

Previous research has shown that while imaging utilization saw explosive growth in the mid-2000s, growth slowed and plateaued near the end of the decade. One aspect that is hidden by looking at overall utilization, but highlighted in the current study, is the growing number of images per exam.

The authors determined that over 539 million images were collected from exams during the study period. CT exams increased from 82 images per exam in 1999 to 679 images per exam in 2010. MRI exams increased from 164 images per exam in 1999 to 570 images per exam in 2010.

McDonald and colleagues list a number of technological advancements over the last 20 years that have helped bring about these high increases in both image quantity and utilization. CT scanners, for example, now exhibit an improved overall design that allows images to be acquired more rapidly. And thanks to parallel imaging techniques, MRI scanners can capture images at a higher resolution.

“These advances, in both acquisition time and resolution, have led to development and implementation of newer imaging techniques that serve to broaden the clinical utility of CT and MRI in the detection of pathology,” the authors wrote. “Collectively, such advances have led to greater imaging volumes, as examination data sets can now contain several thousand images because of their anatomic resolution and complexity of study parameters.”

As the modalities have become faster, physicians have also felt more comfortable relying on them on a regular basis, especially in high-pressure situations, the authors wrote. So improvements that make the technologies more efficient also make them more frequently used.

Mayo did hire additional radiologists to assist with this increase in utilization and images, but McDonald and colleagues found that it wasn’t enough. In 1999, a radiologist interpreting CT scans was required to interpret 2.8 images per minute. In 2010, that same number was over 19 images per minute. Likewise, a radiologist interpreting MRI scans was required to interpret 3 images per minute in 1999, but that number jumped to almost 12 per minute in 2010.

“The modern radiologist must now interpret many times more examination images when compared to similar examinations performed 10–20 years ago,” the authors wrote. “Although these advances in sensitivity and specificity are thought to translate to improved patient care, these increasing imaging volumes are placing an ever-increasing burden on the practicing radiologist. As the workload continues to increase, there is concern that the quality of the health care delivered by the radiologist will decline in the form of increased detection errors as a result of increased fatigue and stress.”

The authors do point out that more research is needed on the exact effect this increased workload has on radiologists, concluding that the topic “merits additional investigation.”