Classification of hepatocellular carcinoma Ki-67 expression status by a simple combination of magnetic resonance slow...

Twenty-two hepatocellular carcinoma (HCC) cases were retrospectively collected from Sichuan Cancer Hospital, Chengdu, China. All were singular lesions with a median size of 4.3 cm. HCC lesions were categorized into low (<20%) and high (≥20%) Ki-67 labeling index (LI) groups. Slow diffusion coefficient (SDC) was derived from b=400 and 800 s/mm² diffusion weighted imaging (DWI) images, and apparent diffusion coefficient (ADC) was derived from b=50 and 800 s/mm² DWI images. On SDC map, relative to the adjacent liver signal, a tumor signal was assigned to six semi-quantitative score (SQS) categories: low signal (score: '0'), iso-signal (score: '1'), slightly high signal (score: '1.5'), high signal (score: '2'), higher signal (score: '2.5'), and markedly high signal (score: '3'). On ADC map, a tumor signal was assigned to 3 SQS categories: low signal (score: '0'), iso-signal (score: '1'), slightly high or high signal (score: '1.5'). HCC lesion SDC SQS was positively and modestly correlated with Ki-67 LI (Spearman rho 0.559), and ADC SQS was negatively and modestly correlated with Ki-67 expression (Spearman rho -0.366). All Ki-67 low expression lesions tended to have an SDC SQS ≤2.0, and SDC SQS ≤1.5 favored the diagnosis of Ki-67 low expression. Only Ki-67 high expression lesions had an SDC SQS ≥2.5. ADC SQS of 1.5 favored the prediction of Ki-67 low expression. A combination of SDC and ADC had an area under the receiver operating characteristic curve (AUROC) of 0.958 for the classification of Ki-67 low vs. high expression.