Regarding the focal treatment of prostate cancer: inference of the Gleason grade from magnetic resonance spectroscopic imaging.
OBJECTIVE
To quantify, as a function of average magnetic resonance spectroscopy (MRS) score and tumor volume, the probability that a cancer-suspected lesion has an elevated Gleason grade.


METHODS
The data consist of MRS imaging ratios R stratified by patient, lesion (contiguous abnormal voxels), voxels, biopsy and pathologic Gleason grade, and lesion volume. The data were analyzed using a logistic model.


RESULTS
For both low and high Gleason score biopsy lesions, the probability of pathologic Gleason score >/=4+3 increases with lesion volume. At low values of R a lesion volume of at least 15-20 voxels is needed to reach a probability of success of 80%; the biopsy result helps reduce the prediction uncertainty. At larger MRS ratios (R > 6) the biopsy result becomes essentially uninformative once the lesion volume is >12 voxels. With the exception of low values of R, for lesions with low Gleason score at biopsy, the MRS ratios serve primarily as a selection tool for assessing lesion volumes.


CONCLUSIONS
In patients with biopsy Gleason score >/=4+3, high MRS imaging tumor volume and (creatine + choline)/citrate ratio may justify the initiation of voxel-specific dose escalation. This is an example of biologically motivated focal treatment for which intensity-modulated radiotherapy and especially brachytherapy are ideally suited.
Brame
Ryan S
RS
CMS, Inc., St. Louis, MO, USA.
Zaider
Marco
M
Zakian
Kristen L
KL
Koutcher
Jason A
JA
Shukla-Dave
Amita
A
Reuter
Victor E
VE
Zelefsky
Michael J
MJ
Scardino
Peter T
PT
Hricak
Hedvig
H
D000465:Algorithms; D001706:Biopsy; D002794:Choline / Q000032:analysis; D019343:Citric Acid / Q000032:analysis; D003401:Creatine / Q000032:analysis; D006801:Humans; D016015:Logistic Models; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D011467:Prostate / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000473:pathology*; D047368:Tumor Burden
D019343:Citric Acid; D003401:Creatine; D002794:Choline