After signing informed consent, patients underwent dMRI prior to starting neoadjuvant chemoradiation. The type of chemotherapy and dose of radiation was not specified in the study protocol; however, most of the patients were enrolled on an unrelated clinical trial and received gemcitabine (1000 mg/m2 on days 1, 8, and 15) plus oxaliplatin (85 mg/m2 on days 1 and 15) with 30 Gy in 2 Gy fractions. MRI scans included a fat saturated gradient recalled echo T1-weighted sequence find more (without and with gadolinium), a fat-saturated fast spin-echo
T2-weighted sequence, a single shot fast spin-echo T2-weighted sequence, a T1-weighted fat suppressed SPGR, and a diffusion sequence. The diffusion weighted technique was single shot diffusion weighted echo-planar with spectral selective fat suppression, with transaxial slices performed in three orthogonal diffusion directions over a range of b-values (0, 100,
500, and 800 s/mm2). The same MRI scanner was used for all patients on the study. All images were obtained with multiple slices to cover the entire selleck chemical tumor volume. The tumor volume, also known as the region of interest, was determined by consensus between an abdominal MR radiologist (H.H.) and the primary investigator (K.C.C.). ADC maps were generated using software created by the University of Michigan (T.L.C., B.D.R., C.J.G., A.R.). Histograms and median/mean ADC values were determined for each scan. The primary objective of the study was to correlate tumor ADC levels and distributions with pathologic and CT
response. Pathologic response was graded according to the system developed by Evans [19]. A single pathologist (J.K.G.) graded each specimen based on the percent of tumor cell destruction. CT response was based on the change in product of the two largest tumor diameters. A secondary objective was to correlate overall survival with pretreatment and post-treatment ADC parameters. Histograms depicting the distribution of voxels within a tumor were extracted from ADC maps which were check details generated from dMRI images. The median and mean ADC values for each histogram/tumor were determined using Excel Software (Microsoft). Pathologic response grading was converted to numerical values of tumor cell destruction as follows Grade I 5%, Grade IIA 30%, Grade IIB 70%, Grade III 95%. Pearson correlation coefficient was calculated to describe the relationship between ADC and percent tumor cell destruction. Student’s t test was used to compare mean ADC values and changes in size on CT scans between groups. A P value of ≤ .05 was considered statistically significant. Between October 2008 and December 2009 we performed a study of dMRI in patients undergoing neoadjuvant chemoradiation for pancreatic cancer. Sixteen patients consented to the study. Four of the patients did not have imaging due to the inability to undergo MRI or the development of metastases prior to starting therapy.