Mammographic interpretive volume and diagnostic mammogram interpretation performance in community practice

To investigate the association between radiologist interpretive volume and diagnostic mammography performance in community-based settings.

This study received institutional review board approval and was HIPAA compliant. A total of 117,136 diagnostic mammograms that were interpreted by 107 radiologists between 2002 and 2006 in the Breast Cancer Surveillance Consortium were included. Logistic regression analysis was used to estimate the adjusted effect on sensitivity and the rates of false-positive findings and cancer detection of four volume measures: annual diagnostic volume, screening volume, total volume, and diagnostic focus (percentage of total volume that is diagnostic). Analyses were stratified by the indication for imaging: additional imaging after screening mammography or evaluation of a breast concern or problem.

Diagnostic volume was associated with sensitivity; the odds of a true-positive finding rose until a diagnostic volume of 1000 mammograms was reached; thereafter, they either leveled off (P < .001 for additional imaging) or decreased (P = .049 for breast concerns or problems) with further volume increases. Diagnostic focus was associated with false-positive rate; the odds of a false-positive finding increased until a diagnostic focus of 20% was reached and decreased thereafter (P < .024 for additional imaging and P < .001 for breast concerns or problems with no self-reported lump). Neither total volume nor screening volume was consistently associated with diagnostic performance.

Interpretive volume and diagnostic performance have complex multifaceted relationships. Our results suggest that diagnostic interpretive volume is a key determinant in the development of thresholds for considering a diagnostic mammogram to be abnormal. Current volume regulations do not distinguish between screening and diagnostic mammography, and doing so would likely be challenging.