Diffusion-weighted Imaging Distortion in Prostate MRI: A Cross-sectional Study Comparing Supine and Prone Positioning

Area of Science:

• Radiology
• Medical Imaging
• Prostate Cancer Diagnostics

Background:

• Diffusion-weighted imaging (DWI) is crucial for multiparametric (mp) prostate MRI.
• Echo-planar DWI techniques are prone to distortion near the recto-prostatic air-tissue interface.

Purpose of the Study:

• To evaluate if prone patient positioning minimizes rectal air and DWI distortion compared to supine positioning.
• To assess the impact of prone positioning on overall image quality.

Main Methods:

• Prospective study of patients undergoing mpMRI for suspected prostate cancer.
• Quantitative measurement of DWI distortion and rectal air volume.
• Qualitative assessment of DWI and T2-weighted imaging (T2WI) using PI-QUAL and Likert scales.

Main Results:

• Prone positioning significantly reduced rectal air volume and improved qualitative DWI quality.
• T2WI quality was significantly inferior in the prone position.
• DWI distortion was reduced in prone positioning for patients with significant rectal air (>4 cm³).
• Prone imaging added an average of 8 minutes 18 seconds to scan time.

Conclusions:

• Prone positioning effectively reduces DWI distortion and rectal air in prostate MRI.
• The benefit of reduced DWI distortion must be weighed against the degradation of T2WI quality.
• Prone positioning is beneficial for DWI quality when rectal air is a concern, but may compromise T2WI assessment.