Evaluation of ADC_ratio on liver MRI diffusion to discriminate benign versus malignant solid liver lesions

The aim of this project is to investigate the usefulness of the absolute liver lesion ADC value and ratio of Apparent diffusion coefficient (ADC) values of a liver lesion and liver parenchyma to discriminate between a benign and malignant lesion.

Liver MRI scans performed between January 2009 and June 2015 were retrospectively analysed. Scans were performed on either a 1.5 T or 3 T MRI unit. The type of liver lesion (benign or malignant) was determined by its radiological appearance, histology result and clinical management. Lesions with undetermined diagnosis or MRI studies degraded by artifacts were excluded. Liver cysts were also excluded from the analysis. ADC value of a lesion and liver parenchyma was measured and ADC_ratio was calculated. The values were analysed using independent samples t-test Results:Data set contained 39 benign lesions and 36 malignant lesions. Mean ADC value for benign lesions was 1678, and the mean value for malignant lesions was 1097 with a statistically significant difference of p < 0.001. All lesions with ADC value below 955 were malignant, while all lesions with ADC value above 1880 were benign. ADC value of 1260 was identified as the best available cut-off value for differentiating benign and malignant lesions, achieving sensitivity of 92%, specificity of 80% and an overall accuracy of 89%. The mean lesion to liver ADC_ratio for benign lesions was 1.3467 and for malignant lesions was 0.9038 with a statistically significant difference of p < 0.001. All lesions with ADC_ratio measuring <0.9 were malignant while lesions with ADC_ratio>1.5 were benign. ADC_ratio of 1.1 was identified statistically as the best available cut-off value for differentiating benign from malignant lesions, with sensitivity of 82%, specificity of 86% and an overall accuracy of 92%.

Our dataset indicates that lesion to background liver ADC_ratio is superior in discriminating between benign and malignant focal lesions compared to absolute ADC values of the hepatic lesions.