Type:
Educational Exhibit
Keywords:
Neoplasia, Cancer, Observer performance, Education, Diagnostic procedure, MR, Abdomen, Pelvis, Genital / Reproductive system male
Authors:
J. Ash-Miles1, H. M. A. OBrien2, P. Charters1, S. HALDAR1; 1Bristol/UK, 2Taunton/UK
DOI:
10.26044/ecr2019/C-0531
Background
In the UK,
prostate cancer is the most common cancer in men and the 2nd most common cause of cancer death1.
Previously,
tissue biopsy was the standard for diagnosing prostate cancer2.
However,
advances in imaging techniques,
especially MRI,
have improved diagnostic precision in identifying prostate malignancy2.
MP-MRI provides information on prostate volume,
vascularity and cellularity in addition to anatomical information2.
The PROMIS trial investigated whether MP-MRI could be used as the initial diagnostic tool to discriminate between men with clinically significant prostate cancer and those without clinically significant disease3.
They used three definitions of clinically significant disease:
-
Primary definition: Gleason score 4+3,
cancer core length 6mm (see figure 1)
-
Secondary definition: Gleason score 3+4,
cancer core length 4mm
-
Any Gleason score 7 (3+4)
They compared the accuracy of MP-MRI and transrectal ultrasound-guided prostate biopsy (TRUS-biopsy),
using template prostate mapping biopsies (TPM-biopsies) as the reference standard. This trial showed that MP-MRI has significantly better sensitivity and negative predictive value for clinically significant prostate cancer compared with TRUS-biopsy,
thus enabling the use of MP-MRI as the initial triage test prior to biopsy.
This enabled one quarter of men to avoid biopsy and its associated complications,
which can include life threatening sepsis3.
It also resulted in a reduction in the number of clinically insignificant cancers diagnosed.
Since the publication of this study,
MP-MRI has been used as the initial triage test for men suspected of having prostate cancer in our tertiary referral centre.
In order to monitor and assess our interpretation and reporting accuracy of these scans and provide learning opportunity in cases of discrepant radiological and pathological findings,
we reviewed all MP MRI prostate scans performed on patients presenting with raised PSA,
over a 3-month period in 2018. A total of 296 examinations were included.
We reviewed the radiological and pathological findings of all examinations scored as PIRADS 1 or 2 on MP MRI that subsequently showed clinically significant prostate cancer on biopsy (false negatives).
We also reviewed the radiology and pathology results of cases scored as PIRADS 4 or 5 that did not subsequently demonstrate malignancy on biopsy (false positives).
We utilised the PROMIS definitions of clinically significant disease as outlined above.
By comparing radiological findings with pathological results,
we identified common pitfalls in image interpretation and present these below.