Role of diffusion weighted MRI imaging in characterization of hepatic focal lesions in cirrhotic patients in comparison to dynamic cross sectional imaging

Abstract

Aim of work The aim of the study is to show the feasibility of diffusion weighted (DWI) MRI with calculation of the apparent diffusion coefficient in characterization of hepatic focal lesions as well as differentiating benign from malignant lesions in cirrhotic patients. Patients and Methods The study included 35 patients (25 males and 10 females) by cross sectional study and convenient sampling at the Demerdash hospital, inclusion criteria: patients diagnosed by hepatic focal lesions on top of post-viral induced cirrhosis, detected by ultrasound, triphasic CT or dynamic MRI imaging. All patients to be included in the study underwent characterization of hepatic focal lesions to differentiate benign from malignant lesions using a combination of characteristic imaging criteria, including contrast enhancement patterns on MRI. Sequences used were T2 weighted imaging, T2 Spectral Attenuated Inversion Recovery (SPAIR), and diffusion weighted imaging sequences with estimation of the ADC map and calculation of the ADC values. Results Our study was carried on a total of 35 patients including 25 males and 10 female patients having a mean age of 59 ± 10.2 years (58.1 ± 11 and 61.2 ± 8 years for the male and female patients respectively). DWI and ADC showed statistically significant difference among the benign and malignant focal lesions in terms of their diffusion restriction criteria ( P < 0.0001), with a sensitivity, specificity, positive and negative predictive values of 100% (95% CI = 89.5 – 100%), 92.3% (95% CI = 79.6 – 97.3%), 91.6% (95% CI = 78.1 – 97.1%) and 100% (95% CI = 90.3 – 100%), as well as a likelihood ratio of 13. On comparing the ADC values of the focal lesions for the benign and malignant focal lesions, the malignant lesions showed statistically significant lower means as compared to the benign lesions (malignant = 1.08 ± 0.28 x 10-3 mm2/s, benign =2.0 ± 0 x 10-3 mm2/s, P < 0.0001). ROC curve analysis of the ADC values of the benign and malignant focal lesions was highly significant (P < 0.0001), with an area under curve of 0.9745 (97.45% overall accuracy), giving an ADC cut-off value of (< 0.98 x 10-3 mm2/s) for malignant lesions with 97.2% sensitivity (95% CI = 85.83% - 99.86%), 97.2% specificity (95% CI = 85.83% - 99.86%) and a likelihood ratio of 35. Summary and conclusion DWI MRI and the calculation of the ADC are great non invasive possible tools to detect and characterize hepatic focal lesions as well as to differentiate benign from malignant lesions in cirrhotic patients especially in patients with renal impairment and allergy to contrast media also to avoid unnecessary biopsies.