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Quantitative Apparent Diffusion Coefficient Derived From Diffusion-Weighted Imaging Has the Potential to Avoid Unnecessary MRI-Guided Biopsies of mpMRI-Detected PI-RADS 4 and 5 Lesions

Polanec, Stephan H., PhD, MD*; Helbich, Thomas H., MD*; Bickel, Hubert, MD*; Wengert, Georg J., MD*; Pinker, Katja, MD*; Spick, Claudio, MD, PhD*; Clauser, Paola, MD*; Susani, Martin, MD; Shariat, Shahrokh, MD; Baltzer, Pascal A.T., MD*,§

doi: 10.1097/RLI.0000000000000498
Original Articles

Objective The aim of this study was to evaluate the potential of diffusion-weighted imaging–derived apparent diffusion coefficient (ADC) measurements to obviate unnecessary biopsies in multiparametric MRI–detected PI-RADS 4 and 5 lesions.

Materials and Methods This retrospective, institutional review board–approved study investigated 101 PI-RADS 4 and 5 prostate lesions (52 malignant, 49 benign) verified by in-bore MRI-guided biopsy in 101 men (mean age, 62.8 years). Two readers, who were not aware of the biopsy results independently and repeatedly measured minimum, mean, and maximum ADC from diffusion-weighted imaging measurements (in line with PI-RADS v2 recommendations) using a 2-dimensional region of interest drawn around the biopsied lesions. Diagnostic performance was evaluated using receiver operating characteristic statistics and reproducibility statistics were calculated.

Results The best diagnostic performance (overall area under the receiver operating characteristic curve [AUC] R1: 0.801; R2: 0.796 peripheral zone AUC R1:0.814, R2: 0.805; transitional zone AUC R1:0.786, R2:0.779) and the tightest limits of interreader agreement (−8.6% to 9.9%) were found in minimum ADC values. Rule-in and rule-out thresholds for diagnosis of prostate cancer were identified, demonstrating a potential to avoid unnecessary biopsies in 32.7% (16/49).

Conclusions Quantitative ADC measurement in multiparametric MRI–detected PI-RADS 4 and 5 lesions has the potential to avoid unnecessary MRI-guided biopsies in up to 33%.

From the *Division of Molecular and Gender Imaging, Department of Biomedical Imaging and Image-Guided Therapy;

Clinical Institute of Pathology, Medical University of Vienna;

Department of Urology, Medical University of Vienna (AKH); and

§Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria.

Received for publication April 24, 2018; and accepted for publication, after revision, May 30, 2018.

The authors report no conflicts of interest.

Correspondence to: Pascal A.T. Baltzer, MD, Division of Molecular and Gender Imaging, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Wien, Austria. E-mail: pascal.baltzer@meduniwien.ac.at.

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