Presented by: Charan Mohan MD
The Smith Institute for Urology, Northwell Health

Introduction

Prostate MRI has been used as a gold standard to determine prostate size allowing for more accurate preoperative surgical planning.  The objective of this study was to assess the performance of MRI in predicting prostate size by comparing the reduction in prostate by surgical weight to postoperative reduction of PSA following laser enucleation of the prostate (LEP).

Materials

A retrospective review was performed on patients undergoing LEP by two fellowship trained surgeons. Thulium Fiber Laser Enucleation was performed using 550-micron laser fiber, and morcellation performed with the Wolf Piranha morcellator©. Preoperative weight was based on prostate volume on MRI assuming 1 mL was equivalent to 1 g of prostatic tissue. Percentage reduction of prostate as measured by preoperative weight and pathology specimen weight was compared to percentage reduction measured by change in PSA preoperatively to 3 months postoperatively.  Additional demographic factors were also obtained.

Results

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30 patients were included in the analysis. Median age was 70 years (IQR 63-73). Median prostate volume on MRI was 115 mL (IQR 90.3-154.8) and median preoperative PSA was 6.5 ng/mL (IQR 4.8-9.9). The median percent change based on prostate weight was 59.1% (IQR 45.9-69.6) compared to median change in PSA which was 90.4% (IQR 79.8-95.1). This difference was statistically significant (p=0.005).

Conclusion

The percent change in PSA following LEP is significantly higher than the presumed reduction in prostate weight. This suggests MRI oversizes prostates in planning for BPH surgery, particularly with larger glands. Possible explanation may be inclusion of all prostatic components in measurement on MRI while only prostatic adenoma is included in postoperative specimens. Alternatively, the conventional density assumption of 1 mL of prostate volume to 1 g of prostatic tissue may not be accurate in larger glands and modifications to this conversion need to be adapted for prostatic composition. Care should be taken when counseling patients on BPH therapy when using imaging measurements, even when MRI is utilized.

Funding

none

Co-Authors

Gregory Mullen, MD
The Smith Institute for Urology, Northwell Health

Jared Winoeker, MD
The Smith Institute for Urology, Northwell Health

Arun Rai, MD, MS, MBA
The Smith Institute for Urology, Northwell Health

Zeph Okeke, MD
The Smith Institute for Urology, Northwell Health

David Hoenig, MD
The Smith Institute for Urology, Northwell Health

Tareq Aro, MD
The Smith Institute for Urology, Northwell Health