Immediate DBT mammo interpretation doesn’t impact performance metrics

Do the pressures of immediate interpretation of digital breast tomosynthesis (DBT) screening exams impact the diagnostic performance of a radiologist? They don’t at the University of Utah’s Radiology and Imaging Services Department in Salt Lake City. Radiologists compared performance metrics of DBT batch interpretation with immediate interpretation to reach their conclusions, which they reported online May 7 in Academic Radiology.

When mammography screening results can be reported immediately, patients may experience less stress and anxiety.¹ Interpretation while the patient is still present also enables technologists to perform additional imaging if necessary, can reduce recalls and related scheduling delays, and can improve patient service. Biopsies may also be performed more rapidly or even the same day. From the perspective of patients and clinicians, the advantages of immediate interpretation are many.²

In 2011, the University of Utah radiology department began offering DBT for breast cancer screening.  Recall rates for this subset of patients dropped to 5%-7%. By 2015, the department was offering all patients DBT screening mammograms in lieu of conventional full-field digital mammography. The department also switched from batch reading to immediate interpretation.

To determine if performance metrics were impacted, the authors compared 18 months of batch-read DBT mammograms (1,212) and six months of immediately interpreted exams (4,306). They evaluated recall rates, cancer detection rates, positive predictive values (PPV) of screening, and biopsy. The PPV included categories for the percentage of all positive screening exams that resulted in a tissue diagnosis of breast cancer, the percentage of abnormal examinations in which biopsies were performed with a breast cancer diagnosis, and the percentage of biopsies performed as a result of a positive diagnostic exam that were diagnosed as breast cancer.

Lead author Nicole S. Winkler, MD, assistant professor of radiology, and colleagues, found no statistically significant difference in recall or cancer detection rates for the two methods. This was also true for all the PPV categories.

When performing immediate DBT screening mammograms, radiologists work in a quiet, secluded room with only minimal interruptions except for urgent phone calls and their own recalls. The authors equated this environment to “batch-screening mammography in real-time.”

“To accommodate for the unpredictability of recalls, the radiologist assigned to ‘real-time’ readings is also responsible for interpreting additional imaging ordered for patients and even same-visit biopsies. Thus, these patients do not interfere with scheduled diagnostic imaging and biopsy resources. With the low rate of callbacks, on most days the impact on imaging workflow is predictable and manageable,” the researchers wrote.  

However, there are days when workflow is negatively impacted with respect to availability of imaging suites. Technologists and interpreting radiologists get overloaded. But the authors write that everyone pitches in to complete the work expediently as possible. A backup diagnostic imaging radiologist will also assist with the immediate interpretation of DBT screening exams so that results can be conveyed to the patient as quickly as possible

The authors are studying the costs associated with batch reading versus immediate interpretation. They will publish their formal cost analysis at a later time.

REFERENCE

1. Lindfors KK, O’Connor J, Parker RA. False-positive screening mammograms: effect of immediate versus later work-up on patient stress. Radiology. 2001 218:247-253.
2. Winkler NS, Freer P, Anzai Y, et al. Impact of immediate interpretation of screening tomosynthesis mammography on performance metrics. Acad Radiol. Published online May 7, 2018. doi: 10.1016/j.acra.2018.04.012