Lower diffusion-derived vessel density (DDVD) measure of liver focal nodular hyperplasia than those of hepatocellular carcinoma and liver metastasis allows potential differential diagnosis: quantitative and semi-quantitative analyses of two-center data.

Background: Focal nodular hyperplasia (FNH) and liver cancers are commonly differentiated by contrast enhanced scan, particularly with the application of hepatobiliary-specific contrast agents. This study aims to investigate the diffusion-derived vessel density (DDVD) difference between liver FNH and liver malignant lesions [hepatocellular carcinoma (HCC) and metastasis].

Methods: The liver diffusion-weighted magnetic resonance imaging (MRI) dataset-1 had 8 cases of FNH, 56 cases of HCC, and 14 cases of liver metastases. Liver diffusion MRI dataset-2 had 10 cases of FNH, 78 cases of HCC. For dataset-1, DDVD and DDVD were calculated from =0 and =10 s/mm images, =0 and =20 s/mm images, respectively. For dataset-2, the measurement was conducted on =0, =2, and b=10 s/mm diffusion-weighted imaging (DWI) images. The ratios of lesion to adjacent liver tissue were taken as: DDVD ratio (DDVDr) = lesion DDVD/liver DDVD. For semi-quantitative analysis on =0 s/mm DWI image and DDVD map, relative to the adjacent liver signal, a liver lesion signal was assigned to five categories: low signal, iso-signal, slightly high signal, high signal, and markedly high signal.

Results: FNH tended to have a lower DDVDr value than malignant lesions, both for dataset-1 (mean DDVDr value, FNH: 1.672, HCC: 5.807, metastases: 7.944) and dataset-2 (mean DDVDr value, FNH: 1.141 HCC: 3.340). For dataset-1, DDVDr had an area under receiver operating characteristic curve (AUROC) of 0.864, and a cutpoint value of >1.923 had a sensitivity of 81.4% and a specificity of 87.5% in suggesting malignancy. For dataset-2, DDVDr had an AUROC of 0.912, and a cutpoint value of >1.845 had a sensitivity of 79.7% and a specificity of 90% in suggesting malignancy. Consistent with quantitative measurement, semi-quantitative scoring showed that a drop from DWI high signal or slightly high signal to DDVD iso-signal suggested the diagnosis of FNH. Dataset-1 showed metastases had a higher DDVD signal than HCC, with markedly high signal on both DWI and DDVD map favoring the diagnosis of metastases.

Conclusions: FNH has a lower DDVD measure compared to HCC and Mets. A drop from DWI high signal or slightly high signal to DDVD iso-signal suggests the diagnosis of FNH.