PEM as an adjunct to MRI or CESM for characterizing non-mass enhancement: a retrospective two-arm diagnostic study

To evaluate the diagnostic performance of positron emission mammography (PEM) as an adjunct to breast MRI or contrast-enhanced spectral mammography (CESM) for characterizing non-mass enhancement (NME).

This retrospective two-arm study included 108 women with NME. Patients were categorized into Arm 1 (MRI + PEM, n = 54) or Arm 2 (CESM + PEM, n = 54). Two experienced radiologists independently reviewed all imaging studies blinded to histopathology. Diagnostic performance metrics were calculated using histopathology as the reference standard.

In Arm 1, PEM demonstrated 100% sensitivity (34/34) and higher specificity (100%, 20/20) compared with MRI (30.0%, 6/20; P < 0.001). In Arm 2, PEM showed 100% sensitivity (28/28) and higher specificity (92.3%, 24/26) compared with CESM (61.5%, 16/26; P < 0.01). Inter-observer agreement was higher for PEM (κ = 0.674) than for MRI (κ = 0.351) and CESM (κ = 0.210). In a combined analysis of 38 indeterminate cases, PEM correctly reclassified 29 of 30 benign lesions.

In this cohort, PEM demonstrated high diagnostic performance and improved specificity when used as an adjunct to MRI or CESM. These findings suggest that PEM may serve as a valuable problem-solving tool in selected indeterminate cases. However, results should be interpreted with caution given the retrospective design and limited sample size.