Comparison of the Diagnostic Performance of Synthetic Versus Acquired High b-Value (1500 s/mm2) Diffusion-Weighted MRI in Women With Breast Cancers

BackgroundAcquired high b-value (>1000 s/mm(2)) diffusion-weighted imaging (DWI) has its strength in lesion detection. However, it is not easily used, due to a lower signal-to-noise ratio, eddy current distortions, and prolonged acquisition times. Synthetic DWI does not have these disadvantages because it is based on indirect acquisition, calculated in a voxel-wise manner. PurposeTo compare the diagnostic performance of synthetic and acquired high b-value (1500 s/mm(2)) DWI in women with breast cancer. Study TypeRetrospective. PopulationA total of 108 patients (median age 49 years [range 32-77]) with 133 breast cancers. Field Strength/Sequence3T, echo-planar imaging. AssessmentThree radiologists independently reviewed image sets of both synthetic (S-b1500) and acquired (A-b1500) high b-value DWI. Malignancy confidence of the lesion was scored using a 6-point Likert-type scale. Statistical TestJack-knife alternative free-response receiver-operating characteristic 1 (JAFROC1) analysis was used. Sensitivity and positive predictive value (PPV) were compared using generalized estimating equations. An independent t-test was used to compare the confidence. An intraclass correlation coefficient was calculated to compare interobserver agreement. ResultsThe JAFROC1 figures of merit values were 0.816 and 0.808 in S-b1500 and A-b1500, respectively, with no statistically significant difference (P=0.637). Sensitivity was higher in synthetic than in A-b1500 for readers 2 (P=0.015) and 3 (P=0.037). Although sensitivity was higher in S-b1500 than in A-b1500 for reader 1, the difference was not significant (P=0.487). The PPV of S-b1500 was not significantly different from that of A-b1500 (P=0.397). The malignancy confidence of true-positive tumors was higher in S-b1500 than in A-b1500 (P=0.013). Interobserver agreement was good for both sequences. Data ConclusionsThe synthetic high b-value DWI may improve the diagnostic sensitivity for breast cancer detection without affecting PPV compared with acquired high b-value DWI. Level of Evidence: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:857-863.