Diffusion-weighted images (DWI) without ADC values in assessment of small focal nodules in cirrhotic liver

摘要

Objective:To assess if diffusion-weighted magnetic resonance(MR) imaging without apparent diffusion coefficient(ADC) values provides added diagnostic value in combination with conventional MR imaging in the detection and characterization of small nodules in cirrhotic liver.Methods:Two observers retrospectively and independently analyzed 86 nodules(≤3 cm) certified pathologically in 33 patients with liver cirrhosis,including 48 hepatocellular carcinoma(HCC) nodules,13 high-grade dysplastic nodules(HDN),10 low-grade dysplastic nodules(LDNs) and 15 other benign nodules.All these focal nodules were evaluated with conventional MR images(T1-weighted,T2-weighted and dynamic gadolinium-enhanced images) and breath-hold diffusion-weighted images(DWI)(b=500s/mm2).The nodules were classified by using a scale of 1-3(1,not seen;3,well seen) on DWI for qualitative assessment.These small nodules were characterized by two radiologists.ADC values weren't measured.The diagnostic performance of the combined DWI-conventional images and the conventional images alone was evaluated using receiver operating characteristic(ROC) curves.The area under the curves(Az),sensitivity and specificity values for characterizing different small nodules were also calculated.Results:Among 48 HCC nodules,33(68.8%) were graded as 3(well seen),6(12.5%) were graded as 2(partially obscured),and 9 weren't seen on DWI.Among 13 HDNs,there were 3(23.1%) and 4(30.8%) graded as 3 and 2 respectively.Five(50%) of 10 benign nodules were partially obscured and slightly hyperintense.For 86 nodules,the average diagnostic accuracy of combined DWI-conventional images was 82.56%,which was increased significantly compared with conventional MR images with 76.17%.For HCC and HDN,the diagnostic accuracy of combined DWI-conventional images increased from 78.69% to 86.07%.Conclusions:Diffusion-weighted MR imaging does provide added diagnostic value in the detection and characterization of HDN and HCC,and it may not be helpful for LDN and regenerative nodule(RN) in cirrhotic liver.