Background: With the advances in magnetic resonance imaging (MR) technology, diffusion-weighted magnetic resonance imaging (DWI) can be used in further characterization of liver lesions and differentiating malignant and benign lesions.

Aims: The purpose of this study was to evaluate focal hepatic lesions using Diffusion Weighted Magnetic resonance imaging and calculate apparent diffusion coefficient (ADC) values, to determine if focal hepatic lesions could be differentiated as benign or malignant by diffusion weighted imaging and ADC maps. Histopathological correlation wherever possible.

Material and Methods: This study was carried out on 40 patients in Department of Radiodiagnosis, Government Medical College, Rajindra Hospital, Patiala. Patients with indeterminate hepatic masses found on USG abdomen and/ CT abdomen were included and MRI abdomen was conducted to characterize liver lesions and ADC values calculated using different b values = 0, 100, 500 and 750 s/mm².ADC values of benign and malignant lesions were compared.

Results: Mean ADC values of malignant focal lesions were significantly lower than benign mass lesions: 0.87 ± 0.15 x10^-3mm²/s V/s 2.66±0.80x10^-3mm²/s respectively (P<0.05). The best ADC threshold value for distinguishing benign and malignant lesions was1.50 x 10^-3mm²/s with Sensitivity =100 %, Specificity = 90.9%, Positive predictive value= 93.33%, Negative predictive value =100% and p value <0.05 respectively.

Conclusion: DWI and ADC can better characterize focal hepatic lesions. DWI can be used as an additional sequence to the standard protocol study and not as a unique imaging series.Since there could be substantial overlap in the range of ADCs between different pathologies, the ADC should be interpreted concurrently with all available imaging before making the radiologic diagnosis.

Keywords: DW MRI liver; Hepatic focal lesions; ADC of hepatic focal lesions; Benign and malignant lesions; ADC cut-off.

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Dr Sachin Kumaraswamy

Junior Resident, Department of Radiodiagnosis, Government Medical College, Patiala, Punjab, India