MRI-based thermal dosimetry and diffusion-weighted imaging of MRI-guided focused ultrasound thermal ablation of uterine fibroids.
OBJECTIVE
To investigate tissue changes observed in diffusion-weighted imaging (DWI) and its relation to contrast imaging, thermal dosimetry, and changes in the apparent diffusion coefficient (ADC) after MRI-guided focused ultrasound surgery (MRgFUS) of uterine fibroids.


METHODS
Imaging data were analyzed from 45 fibroids in 42 women treated with MRgFUS. The areas of the hyperintense regions in DWI and of nonperfused regions in T1-weighted contrast enhanced imaging (both acquired immediately after treatment) were compared with each other and to thermal dosimetry based estimates. Changes in ADC were also calculated.


RESULTS
Hyperintense regions were observed in 35/45 fibroids in DWI. When present, the areas of these regions were comparable on average to the thermal dose estimates and to the nonperfused regions, except for in several large treatments in which the nonperfused region extended beyond the treated area. ADC increased in 19 fibroids and decreased in the others.


CONCLUSIONS
DWI changes, which includes changes in both in T2 and ADC, may be useful in many cases to delineate the treated region resulting from MRgFUS. However, clear DWI changes were not always observed, and in some large treatments, the extent of the nonperfused region was under estimated. ADC changes immediately after MRgFUS were unpredictable.
Pilatou
Magdalini C
MC
Department of Radiology, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts, USA. mcpilatou@bwh.harvard.edu
Stewart
Elizabeth A
EA
Maier
Stephan E
SE
Fennessy
Fiona M
FM
Hynynen
Kullervo
K
Tempany
Clare M C
CM
McDannold
Nathan
N
D000328:Adult; D003287:Contrast Media / Q000008:administration & dosage; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage; D006801:Humans; D007889:Leiomyoma / Q000628:therapy*; D053783:Magnetic Resonance Imaging, Interventional / Q000379:methods*; D008875:Middle Aged; D012189:Retrospective Studies; D013817:Thermography / Q000379:methods*; D014464:Ultrasonic Therapy / Q000379:methods*; D014594:Uterine Neoplasms / Q000628:therapy*
D003287:Contrast Media; D019786:Gadolinium DTPA