Nienke Lynn Hansen MD, Presenter: Nothing to Disclose

Simone Schrading MD, Abstract Co-Author: Nothing to Disclose

Alexandra Barabasch MD, Abstract Co-Author: Nothing to Disclose

Kevin Strobel PhD, Abstract Co-Author: Nothing to Disclose

Christiane Katharina Kuhl MD, Abstract Co-Author: Advisory Board Member, Bayer AG

Purpose of our study was to determine the influence of the degree of background enhancement on sensitivity, specificity and positive predictive value (PPV) of breast MRI.

335 women with 494 breasts underwent dynamic contrast-enhanced breast MRI in our institution (median age 55, 25-86 years) from May 2010 to November 2012. Background enhancement in MRI was scored on a 4-point-scale from absent to strong. BIRADS diagnoses were assigned per breast. BIRADS6 lesions were excluded from analysis. Diagnoses were validated either by biopsy (BIRADS 4/5) or MRI follow-up (BIRADS 1-3) (average 14 months, 12-27 months). Sensitivity, specificity and PPV were calculated and compared for all classes of background enhancement. Fisher’s exact test was used for statistical analysis.

A total 378 (77%) benign and 116 (23%) malignant diagnoses were validated in the 494 breasts. 9% (45/494) of lesions were classified as DCIS (mean size 28 mm, range 7-100 mm), 14% (71/494) as invasive carcinoma (mean size 17 mm, range 0.5-11 mm). The distribution of MR-ACR categories in the 335 patients was as follows: MR-ACR1 in 187/335 (56%), 2 in 92/335 (27%), 3 in 41/335 (12%), and MR-ACR4 in 15/335 (4%). Sensitivity of MRI in breasts categorized as MR-ACR1, 2, 3, and 4 was 98% (64/65), 100% (31/31), 100% (15/15), and 100% (5/5), respectively (p=1). Specificity of breast MRI in breasts categorized as MR-ACR1, 2, 3, and 4 was 83% (175/211), 72% (76/105), 57% (26/46) and 38% (6/16) (p=0.000019). PPV was 64% (64/100), 52% (31/60), 43% (15/35) and 33% (5/15). 

Background enhancement does not seem to interfere with our ability to identify invasive breast cancers and DCIS in MRI. This, however, is achieved at the expense of specificity and PPV, which decreases significantly with stronger background enhancement.

The accuracy of breast MRI decreases with increasing background enhancement; a compromise on specificity appears unavoidable. However, PPV levels appear still acceptable in women with MR-ACR 3 and 4.

Hansen, N, Schrading, S, Barabasch, A, Strobel, K, Kuhl, C, Does Background Enhancement Influence Diagnostic Accuracy of Breast MRI?.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13044269.html