Keywords:
Gastrointestinal tract, MR-Diffusion/Perfusion, PET-CT
Authors:
N. Gong, C. S. Wong, Y. C. T. Chu, J. Gu; Hong Kong/CN
DOI:
10.1594/ecr2012/C-1906
Methods and Materials
A.Patients and Treatment
Between September 2010 and November 2011,
7 patients with histopathological proof of metastatic GIST in a single institution (***) were enrolled into the present study.
Patients with contraindication to MRI and claustrophobia were excluded.
All recruited patients underwent PET/CT scans first and then MRI scans at diagnosis.
Totally 37 lesions were found.
And they were later treated with Imatinib Mesylate.
Between December 2010 and November 2011,
6 out of 7 patients had follow-up MRI and PET/CT examinations within an average interval of 12 weeks from baseline.
One patient was defaulted.
B.
Diffusion Weighted Imaging
All pre- and post-treatment MR images were acquired by a 3T scanner (Achieva; Philips Healthcare) with patients in supine position.Patients were asked to fast for 4 h before MRI.
A technique similar to Diffusion Weighted Imaging with Background Body Signal Suppression was used.
Free-breathing DWI was obtained in transverse plane using a single-shot echo planar imaging (EPI) sequence with short TI inversion recovery (STIR) fat-suppression and slice-selection gradient reversal technique.
C.PET/CT Imaging
All pre- and post-treatment PET/CT examinations were performed on a PET/CT scanner (Discovery VCT,
GE Healthcare Bio-Sciences Corp.).
D.Treatment Response Criteria
PET/CT was used as a standard of reference for treatment response categorization.
An experienced radiologist specialist (***,
9 years experience) determined the response on PET/CT images.
Treatment responses in diffusion weighted images were determined by another radiologist specialist (***,
9 years experience) who was blinded to the PET/CT data
E.SUV Measurement
PET/CT data evaluation was performed on a workstation (Advantage Workstation,
4.3,
GE Healthcare) by a radiologist,
who was blinded to the MRI results.
F.ADC Measurement
ADC map was reconstructed on a pixel basis from diffusion weighted images with three b values: 0,
150,
and 1000 s/mm2 using the standard software on the imaging console (Achieva; Philips Healthcare).