Potential of Noncontrast Magnetic Resonance Imaging With Diffusion-Weighted Imaging in Characterization of Breast Lesions: Intraindividual Comparison With Dynamic Contrast-Enhanced Magnetic Resonance Imaging

Abstract

Objectives: The aim of this study was to assess the potential of noncontrast magnetic resonance imaging (NC-MRI) with diffusion-weighted imaging (DWI) in characterization of breast lesions in comparison to dynamic contrast-enhanced MRI (DCE-MRI) at 3 T.

Materials and methods: Consecutive patients with conventional imaging (mammography, ultrasound) BI-RADS 4/5 findings were included in this institutional review board-approved single-center study. All underwent 3 T breast MRI including readout-segmented DWI, DCE, and T2-weighted sequences. Final diagnosis was defined by histopathology or follow-up (>24 months). Two experienced radiologists (R1, R2) independently assigned lesion conspicuity (0 = minimal to 3 = excellent) and BI-RADS scores to NC-MRI (readout-segmented DWI including apparent diffusion coefficient maps) and DCE-MRI (DCE and T2-weighted). Receiver operating characteristics, κ statistics, and visual grading characteristics analysis were applied.

Results: Sixty-seven malignant and 56 benign lesions were identified in 113 patients (mean age, 54 ± 14 years). Areas under the receiver operating characteristics curves were similar: DCE-MRI: 0.901 (R1), 0.905 (R2); NC-MRI: 0.882 (R1), 0.854 (R2); P > 0.05, respectively. The κ agreement was 0.968 (DCE-MRI) and 0.893 (NC-MRI). Visual grading characteristics analysis revealed superior lesion conspicuity by DCE-MRI (0.661, P < 0.001).

Conclusions: Diagnostic performance and interreader agreement of both NC-MRI and DCE-MRI is high, indicating a potential use of NC-MRI as an alternative to DCE-MRI. However, inferior lesion conspicuity and lower interreader agreement of NC-MRI need to be considered.

Figure 1:

59 year old patient with a T1c invasive ductal cancer G3. Readout-segmented DWI image at b=850 s/mm² (A) shows ill-defined strongly hyperintense lesion (arrow) with corresponding low Apparent Diffusion Coefficient values on the ADC map (B). Note the similar contrast and morphologic appearance as compared to the T1w contrast enhanced TWIST image (C) and the T2w-TSE image (D).

Figure 2:

Comparison of morphologic assessment on NC-MRI and CE-MRI. A shows a circumscribed round lesion on the b850 s/mm² image (dashed arrow) while B visualizes a non-circumscribed, rather spiculated lesion on the b850 s/mm² image (arrow). The lesion from A appears with circumscribed margins on the early contrast-enhanced subtraction (C, dashed arrow) and was histologically proven as a fibroadenoma while the lesion from B appears non-circumscribed with heterogeneous internal structure and a feeding vessel on the early contrast-enhanced subtraction (D, arrow) and corresponds to an invasive ductal carcinoma G2.

Figure 3:

Binominal fitted Visual Grading Characteristics (VGC) Curve comparing lesion conspicuity in readout-segmented DWI (NC-MRI) and contrast enhanced MRI (DCE-MRI) reveals an area under the curve of 0.661. The curve significantly (P<0.001) deviates from the null hypothesis (0.5, diagonal line) towards the CE-MRI axis which can be interpreted as a superior lesion conspicuity of CE-MRI compared to NC-MRI.

Figure 4:

Receiver Operating Characteristics Curve of BI-RADS ratings for reader 1 (R1) and reader 2 (R2) in readout-segmented DWI (NC-MRI) and contrast enhanced MRI (DCE-MRI).

Figure 5:

Lesion conspicuity of a small carcinoma (5mm, arrow) in a 53-year old patient. The lesion shows excellent conspicuity on the early contrast-enhanced subtraction (A) while it is adequately visualized on the b850 s/mm² image (B). The corresponding ADC map shows a hypointense lesion correlate, corresponding to low ADC-values (0.8 *10⁻³ mm²/s.