Out of the patients who went to surgery, three were found to be unresectable at the time of their operation and seven MK0683 research buy patients successfully underwent pancreaticoduodenectomy. The median time from the pretreatment dMRI to the start of chemoradiation was 3.5 days (range, 1–63). Pathologic response measured as percent tumor cell destruction was graded by a pathologist (JKG) (Table 1). There was one Grade I response (> 90% viable tumor), one Grade IIA response (11–50% tumor cell destruction), two Grade IIB responses (51–90% tumor cell destruction), and three Grade III responses (minimal viable tumor). We determined the

mean ADC for each tumor prior to treatment with neoadjuvant chemoradiation. The mean pretreatment ADC for the entire group was 144.2 × 10− 5 mm2/s (SD 27.9). Representative images of a tumor with a low ADC value and a high ADC value are shown in Figure 1.

There was a significant direct linear correlation between pre-treatment ADC and percent tumor cell destruction with a Pearson’s r coefficient of 0.94 (P = .001) and an R2 value of 0.90 ( Figure 2). Analysis on ADC histograms for each tumor further demonstrated that tumors with increased tumor cell destruction from chemoradiotherapy were shifted towards higher ADC values ( Figure 3). ADC histograms http://www.selleckchem.com/screening/chemical-library.html were approximately 150 × 10− 5 mm2/sec in width for each tumor. The tumors with the least amount of cellular destruction after chemoradiation demonstrated a high degree of restricted diffusion at baseline or low ADC values. Responsive tumors had mean ADCs above 150 3-mercaptopyruvate sulfurtransferase × 10− 5 mm2/s with a minimal amount of voxels below an ADC of 100 × 10− 5 mm2/sec. Mean pretreatment ADC was significantly higher in patients who had a pathologic response defined as minimal (< 10%) viable tumor (ADC 161 × 10− 5 mm2/s +/− 5, n = 3) compared to patients with a poor pathologic response (ADC 125 × 10− 5 mm2/s +/− 16, n = 4). In contrast, there was no significant change in tumor size seen on CT imaging obtained prior to and

after chemoradiation in responding or non-responding patients (Figure 4). Patients who had > 90% tumor cell destruction (Grade III response) had a median survival of 25.6 months, whereas patients who had greater than 10% viable tumor remaining (Grade I-IIB response) after chemoradiation had a median survival of 18.7 months. Patients with unresectable tumors had a median survival of 6.1 months. All patients with a mean pretreatment tumor ADC of < 145 had either viable tumor remaining after chemoradiation or were unresectable. Three of the five patients with an ADC > 145 x 10− 5 mm2/s underwent surgery and were found to have minimal viable tumor remaining after chemoradiation. Due to the high prevalence of metal biliary stents in our patient population and the potential artifact on diffusion weighted sequences, we tested three metal biliary stents to determine the feasibility of including these patients on dMRI studies.