Prostate MRI and orthopedic artifact

Case contributed by Dr Ian Bickle

Presentation

Prior biopsy proven malignancy. Now rising PSA.

Patient Data

Age: 70 years
Gender: Male

Prostate volume 32mls.  Rising PSA 0.35ng/ml.

The whole left peripheral zone is occupied by PIRADS 5.  Long capsular abutment, but no extracapsular extension.  Normal right lobe.

Minor BPH.

Normal seminal vesicles.  No pelvic nodes.  No bone metastases.

Case Discussion

Metallic artefact from orthopedic procedures hugely degrade the DWI and ADC sequences in prostate MR imaging.  These are vital sequences which largely determine the PIRADS status of focal abnormalities observed on T2..

In this case the lesion is so large that despite the distortion enough of the T2 visible abnormality is demonstrated on the DWI (b1400) and ADC maps to confirm a PIRADS 5 lesion occupying the whole of the peripheral zone of the left lobe.

Often the distortion is too great for a lesion to be fully classified and only the T2 images can be used for a judgment call.  Strictly speaking then the maximum PIRADS one can state is PIRADS 3.

This cases was due to a ORIF from of a prior pelvic fracture, but it is typically hip replacements, dynamic hip screws and hemiarthroplasties responsible for the artefact.  This is the nature of the patient population being largely senior males.

You can observe just how susceptible the DWI and ADC sequences are compared to T1 and T2 in this case.

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Case information

rID: 85969
Published: 15th Jan 2021
Last edited: 15th Jan 2021
System: Urogenital
Inclusion in quiz mode: Included

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