Objectives: To evaluate the incremental value of diffusion weighted imaging (DWI) in
addition to magnetic resonance cholangiopancreat-ography (MRCP) in diagnosing extrahepatic
cholangiocarcinoma (EHCC); to determine the most appropriate b value for DWI on 3.0 T MRI.
Methods: Preoperative MRI examinations were performed for 63 patients with suspected EHCC.
The examinations included T2-weighted imaging, coronal fast imaging employing steady-state acquisition
(FIESTA), MRCP and DWI sequence with different b values (500, 1000 and 1200s/mm2).
All cases were confirmed by histopathological diagnosis. Two radiologists in consensus reviewed
MRCP imaging and combined MRCP and DWI imaging with ADC maps, and apparent diffusion
coefficient (ADC) value, signal-noise ratio (SNR), contrast-to-noise ratio (CNR) and signalintensity
ratio (SIR) under various b values were calculated.
Results: There were significant differences in sensitivity (74.4% vs. 94.9%), specificity (75% vs.
100%) and accuracy (74.6% vs. 96.8%) between MRCP alone and combined MRCP and DWI with
a b value of 1000 s/mm2 (P<0.05). There was also a significant difference in ADC, SNR, CNR and
SIR under various b values (P<0.05).
Conclusion: For diagnosing EHCC, the combined use of MRCP and DWI shows a better diagnostic
performance than MRCP alone; the b value of 1000 s/mm2 is the most appropriate for DWI on