MRI-guided HDR prostate brachytherapy in standard 1.5T scanner.
OBJECTIVE
Magnetic resonance imaging (MRI) provides superior visualization of the prostate and surrounding anatomy, making it the modality of choice for imaging the prostate gland. This pilot study was performed to determine the feasibility and dosimetric quality achieved when placing high-dose-rate prostate brachytherapy catheters under MRI guidance in a standard "closed-bore" 1.5T scanner.


METHODS
Patients with intermediate-risk and high-risk localized prostate cancer received MRI-guided high-dose-rate brachytherapy boosts before and after a course of external beam radiotherapy. Using a custom visualization and targeting program, the brachytherapy catheters were placed and adjusted under MRI guidance until satisfactory implant geometry was achieved. Inverse treatment planning was performed using high-resolution T(2)-weighted MRI.


RESULTS
Ten brachytherapy procedures were performed on 5 patients. The median percentage of volume receiving 100% of prescribed minimal peripheral dose (V(100)) achieved was 94% (mean, 92%; 95% confidence interval, 89-95%). The urethral V(125) ranged from 0% to 18% (median, 5%), and the rectal V(75) ranged from 0% to 3.1% (median, 0.3%). In all cases, lesions highly suspicious for malignancy could be visualized on the procedural MRI, and extracapsular disease was identified in 2 patients.


CONCLUSIONS
High-dose-rate prostate brachytherapy in a standard 1.5T MRI scanner is feasible and achieves favorable dosimetry within a reasonable period with high-quality image guidance. Although the procedure was well tolerated in the acute setting, additional follow-up is required to determine the long-term safety and efficacy of this approach.
Radiation Oncology Branch, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bldg. 10, Rm. B3B69, 9000 Rockville Pike, Bethesda, MD 20892, USA.
Cynthia
C
Ménard
Robert C
RC
Susil
Peter
P
Choyke
Gary S
GS
Gustafson
William
W
Kammerer
Holly
H
Ning
Robert W
RW
Miller
Karen L
KL
Ullman
Nancy
N
Sears Crouse
Sharon
S
Smith
Etienne
E
Lessard
Jean
J
Pouliot
Victor
V
Wright
Elliot
E
McVeigh
C Norman
CN
Coleman
Kevin
K
Camphausen
D000368:Aged; D001918:Brachytherapy / Q000379:methods*; D016001:Confidence Intervals; D005240:Feasibility Studies; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D014546:Urinary Catheterization / Q000379:methods