An example of the utility of multiparametric MRI in the detection of prostate cancer

 

Utility of multiparametric MRI in the detection of prostate cancer

Mr B is a fit and healthy 55 year-old builder who had an elevated screening PSA (prostate specific antigen) of 5.4 (normal for his age <3.0).

The test was performed by his GP as part of a routine yearly check up.  His PSA had previously always been within the normal limits for his age. His family doctor arranged a repeat PSA and referred him to Melbourne Urology Centre for further investigation.

History

A thorough history was taken.  Mr B had some mild lower urinary tract symptoms, getting up once at night to pass urine. His symptoms were often worse after drinking alcohol but of minimal bother and not requiring any treatment. There was no history of urinary tract infection or haematuria (blood in the urine). There was no family history of prostate cancer but Mr B’s father had surgery for BPH (benign prostatic hyperplasia).

Examination

On digital rectal examination (DRE) the prostate was slightly enlarged but smooth and benign-feeling with no nodules.

Investigations

A repeat PSA including free-to-total ratio remained elevated at 5.3. Urine microscopy and culture showed no sign of an infective process to explain the elevated PSA reading. Renal tract ultrasound showed a mildly enlarged 47cc prostate with a small 30ml post void residual volume.

A multi-parametric prostate MRI was arranged which demonstrated a suspicious 1cm lesion in the anterior aspect of the prostate (see image). This was reported as PIRADS 4 (high probability of clinically significant prostate cancer).

MRI fusion transperineal prostate biopsy was arranged, enabling accurate targeted biopsy of the suspicious area, along with a template biopsy of the remainder of the prostate. The procedure was performed as a day case, without complication.

The prostate biopsy results showed Gleason 4+4=8 high-grade prostate cancer in the targeted biopsy cores only. The remainder of the biopsies were benign.

Treatment

After an in-depth discussion of the treatment options, Mr B decided to proceed with robotic radical prostatectomy for curative treatment of his high-grade prostate cancer. A more detailed account will be provided in a further case-study.

Discussion points – Role of MRI and transperineal prostate biopsy

  • Most (~70%) of prostate cancers occur in the peripheral zone. This is the outer region away from the urethra.
  • Anterior tumours may be missed on trans-rectal biopsy and are not palpable on DRE but can be easily accessed with a transperineal biopsy.
  • Small tumours may be missed on template transperineal biopsy without MRI
  • Use of MRI fusion biopsy minimizes chance of false negative biopsy (ie missing a cancer that is present).
  • MRI provides valuable information for:
    • Targeting and localising lesions for biopsy
    • Accurate staging of disease – assessing for extracapsular tumour extension
    • Surgical planning for nerve sparing
  • A high quality MRI and experienced radiologist reporting the scans is essential