1. What is the appropriate margin for focal therapy of prostate cancer when using MRI/MRSI for treatment planning?
Proposed secondary study for ACRIN 6659 data
Fergus Coakley MD, Professor of Radiology and Urology,
Chief, Abdominal Imaging, University of California San Francisco

2. Objective
Determine the appropriate margin for focal therapy of prostate cancer when planned from MRI/MRSI

3. Background
Increasing interest in focal therapy as “middle way” for prostate cancer treatment
Active surveillance – minimalist
Definitive treatment (RRP or RT) – high morbidity
Three requirements for focal therapy:
Clinical selection – no consensus
Radiological selection – MRI criteria on next slide
Adequate margin – purpose of this proposal

4. UCSF selection study
88 patients with MRI/MRSI before RRP and with detailed tumor maps
MRI/MRSI reviewed by two independent readers
Dominant treatable foci = largest lesion & > 0.5cc
Results:
ALL visible lesions on T2 with ≥0.54 cm3 of concordant MRSI abnormality (n = 27 and 25 for reader 1 and 2, respectively) were correctly identified dominant treatable tumor foci

5. Proposal (two steps) Apply UCSF criteria to ACRIN database
T2 visible & ≥0.54 cm3 concordant MRSI
Two readers (remote or travel to ACRIN HQ?)
Anticipate small number will meet criteria (<10?)
Co-register digital pathology with T2
Pick largest/best T2 image and “best match” pathology slide
Morph gland outline on pathology to T2 (allows margin measurement using MRI calipers)
Measure maximum margin (per quadrant and separate capsular from non-capsular?)

6. “Best match” T2 MRI and pathology slice
Example
“Best match” T2 MRI and pathology slice

7. Example
“Morph” pathology to T2

8. Example
“Morph” pathology to T2

9. Measure margins – maximum capsular and non-capsular plus by quadrant?
Example
Measure margins – maximum capsular and non-capsular plus by quadrant?

10. Analysis
Presumably will be essentially descriptive – what margin would have encompassed all the tumors?
Issues for discussion:
Explore additional selection criteria?
More than two reads?
Can readings be done remotely?
Who will fuse images and measure margins?
Funding level? Travel and/or time?