3 T v 1.5 T MRI prostate with total hip prosthesis

Case contributed by Dr Chris O'Donnell

Presentation

Status post abdominoperineal resection for low rectal cancer and right total hip prosthesis. Elevated PSA.

Patient Data

Age: 65 years
Gender: Male

Very severe susceptibility artifact produced by the right total hip prosthesis causing the DWI images to be non-diagnostic.  The patient was therefore referred for repeat 1.5 T MRI prostate.

Less susceptibility artifact from the right hip prosthesis using the same b value.  PI-RADS 5 lesion of >15 mm in the left anterior prostate with reduced "smudgy" T2 signal and restricted diffusion on the DWI and ADC.  Biopsy was very difficult as transrectal ultrasound could not be used. Using the perineum as the acoustic window, transperineal prostate biopsy confirmed Gleason 3+3 cancer, although MRI suggests a higher Gleason score.

Case Discussion

Multiparametric MRI prostate has rapidly increased in popularity in the last three years following the release of PI-RADS v2 in 2015.  It is a robust reporting protocol and can be used for both 1.5 and 3 T MRI scanners although 3 T has become the standard especially for DWI sequences with long b values (DWI being the keystone to cancer diagnosis, especially in the peripheral zone).  Susceptibility artifact is heightened with the use of 3 T especially in relation to bowel gas in the rectum and any metal hardware such as a hip prosthesis.  This has been addressed to some degree by meticulous bowel preparation and use of different EPI sequences for DWI acquisition including read-out segmented multishot EPI rather than single shot effectively reducing the Te.  Modern 1.5 T MRI of the prostate with improved gradients can produce very diagnostic images and, as in this case, are less prone to susceptibility artifact.

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Case information

rID: 57273
Published: 16th Dec 2017
Last edited: 26th Mar 2018
System: Urogenital
Inclusion in quiz mode: Included

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