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E1108. Beyond PI-RADS v2.1: Adding Value to the Prostate MRI Protocol
Authors
  1. Anup Shetty; Mallinckrodt Institute of Radiology/Washington University School of Medicine
  2. Maria Zulfiqar; Mallinckrodt Institute of Radiology/Washington University School of Medicine
  3. Daniel Ludwig; Mallinckrodt Institute of Radiology/Washington University School of Medicine
  4. Mark Hoegger; Mallinckrodt Institute of Radiology/Washington University School of Medicine
  5. David Ballard; Mallinckrodt Institute of Radiology/Washington University School of Medicine
  6. Daniel Young; Mallinckrodt Institute of Radiology/Washington University School of Medicine
Background
Multiparametric MRI (mpMRI) has become an integral component in the management of prostate cancer, improving the detection of clinically significant prostate cancer and helping to reduce the overdiagnosis and treatment of clinically insignificant prostate cancer [1]. Prostate Imaging Reporting and Data System version 2.1 (PI-RADS v2.1) prescribes minimum technical standards for performing prostate mpMRI, yet a high degree of variability exists in protocol design and quality [2]. Appropriate sequence selection and optimization can greatly enhance the diagnostic value and utility of mpMRI, particularly in the assessment of nodal and osseous metastatic disease, detection of extraprostatic tumor extension, and identification of other clinically significant extraprostatic findings. Metal artifact reduction and preparation for mpMRI-ultrasound fusion biopsy are also important facets of practical mpMRI protocol design [3]. The purpose of this case-based exhibit is to demonstrate how optimization beyond PI-RADS v2.1 minimal standards can improve the diagnostic value and utility of mpMRI.

Educational Goals / Teaching Points
This exhibit will familiarize the reader with the minimal technical standards specified by PI-RADS v2.1. Using a case-based approach, different methods for primary sequences (i.e., T1, T2, and diffusion-weighted imaging [DWI]) will be reviewed, highlighting the strengths, weaknesses, and trade-offs including scan time, spatial resolution, artifact reduction, lesion conspicuity, and problem solving. The utility of specific MR sequences for metal artifact reduction in patients with hip arthroplasties will be demonstrated. The value of fast full field of view (FOV) sequences for lymph node and bone evaluation plus detection of extraprostatic findings will be illustrated. After reviewing the exhibit, the reader should have the knowledge to optimize their current prostate mpMRI protocol.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The imaging techniques and minimum standards required by PI-RADS v2.1 for primary sequences will be reviewed. Strategies for metal artifact reduction include the use of spin-echo view-angle tilting and high bandwidth readout, segmented multishot echo planar DWI, and small FOV selective excitation DWI. Full FOV sequences such as T2 single-shot fast-spin echo, DWI, and chemical shift Dixon 3D spoiled gradient echo pre- and post-contrast sequences with fat-only and water-only reconstructions and automated subtraction drastically improve the depiction of important extraprostatic findings.

Conclusion
As prostate MRI rapidly grows in volume, optimization of the protocol beyond the minimum standards of PI-RADS v2.1 will aid in detection and staging of prostate cancer, facilitate more accurate fusion biopsy, decrease artifacts, improve diagnostic confidence, and reduce the time needed for exam interpretation.