Quantitative MR imaging assessment of prostate gland deformation before and during MR imaging-guided brachytherapy.
OBJECTIVE
The authors performed this study to document the deformations that occur between pretreatment magnetic resonance (MR) imaging and intraoperative MR imaging during brachytherapy.


METHODS
MR images obtained at 1.5 and 0.5 T in 10 patients with prostate cancer were analyzed for changes in the shape and substructure of the prostate. Three-dimensional models of the prostate were obtained. The authors measured anteroposterior dimension; total gland, peripheral zone, and central gland volumes; transverse dimension; and superoinferior height.


RESULTS
Gland deformations were seen at visual inspection of the three-dimensional models. The anteroposterior dimension of the total gland, central gland, and peripheral zone increased from 1.5- to 0.5-T imaging (median dimension, 4.9, 1.5, and 1.8 mm, respectively), and the increase was greatest in the peripheral zone (P < .05, all comparisons). There was a decrease in the transverse dimension from 1.5- to 0.5-T imaging (median, 4.5 mm; P < .005). The total gland volume and the superoinferior height did not show a statistically significant change.


CONCLUSIONS
There were significant deformations in the shape of the prostate, especially in the peripheral zone, between the two imaging studies. The likely causes of the shape change are differences in rectal filling (endorectal coil used in 1.5-T studies vs obturator in 0.5-T studies) and/or changes in patient position (supine vs lithotomy). These findings suggest that pretreatment images alone may not be reliable for accurate therapy planning. It may be useful to integrate pre-and intraoperative data.
Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
Masanori
M
Hirose
Aditya
A
Bharatha
Nobuhiko
N
Hata
Kelly H
KH
Zou
Simon K
SK
Warfield
Robert A
RA
Cormack
Anthony
A
D'Amico
Ron
R
Kikinis
Ferenc A
FA
Jolesz
Clare M C
CM
Tempany
D001918:Brachytherapy / Q000379:methods; D006801:Humans; D021621:Imaging, Three-Dimensional; D007430:Intraoperative Care; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010347:Patient Care Planning; D011300:Preoperative Care; D011467:Prostate / Q000473:pathology* / Q000528:radiation effects; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000473:pathology* / Q000532:radiotherapy* / Q000601:surgery; D015203:Reproducibility of Results; D012189:Retrospective Studies