Assessment of mild chronic pancreatitis：the utility of diffusion weighted imaging before and after secretin stimulation / 中华放射学杂志

ABSTRACT

Objective To explore the diagnostic value of DWI after secretin stimulation for the diagnosis of mild chronic pancreatitis (CP). Methods This was a prospective study. Ninety-nine consecutive individuals including 23 healthy volunteers, 11 risk volunteers, 15 mild CP patients, 14 moderate CP patients and 36 severe CP patients underwent secretin DWI and faecal elastase 1(FE-1) testing. The subjects were grouped by Cambridge classification about endoscopic retrograde cholangiography (ERCP), CT and ultrasonography. Secretin stimulated diffusion weighted imaging(S-DWI), the ADCs, time to peak ADCs and FE-1 were performed on all subjects. The changes of pancreatic ADC values were observed before and after the injection of secretin. All ADCs and FE-1 were compared between groups with single factor analysis of variance, and the correlation between ADCs and FE-1 was determined with Pearson analysis. ROC curves were performed to identify the diagnostic efficacy of DWI related measures. Results Eight patients with severe CP were excluded because the significant atrophy of the pancreatic parenchyma prohibited the evaluation of ADC measurement. Ninety-one individuals were divided into five groups including 23 healthy volunteers, 11 risk volunteers, 15 mild CP patients, 14 moderate CP patients and 28 severe CP patients. The mean baseline and peak ADCs were higher in the healthy volunteers than in other groups, with significant differences (P<0.05). There was no ADC peak in severe CP patients. There were significant differences between the mean baseline ADCs and the peak ADCs in the other groups (P<0.05). The mild and moderate CP groups showed a delayed peak. The area under curve (AUC) of the mean baseline and peak ADCs, time to peak ADCs for differentiating mild CP was 0.818, 0.912 and 0.965, respectively. Using 4.67 min as the cutoff value, time to peak ADCs were most accurate for differentiating healthy from risk patients and those with evident pancreatitis, yielding a sensitivity of 80.0%and a specificity of 100.0%. Good correlations between baseline and peak ADCs, time to peak ADCs, and FE-1 were shown(r=0.57, 0.72 and-0.84, P<0.01). Conclusions Using the peak and time to peak ADCs may improve the detection of risk and mild CP. Secretin-enhanced DWI is a noninvasive, convenient and accurate method.