Role of Triple Phase Computed Tomography in the Evaluation of Liver Lesions

Abstract

Introduction: Wide range of benign and malignant tumours can occur in the liver, the largest organ in our body. So far, the histopathological diagnosis was considered the gold standard with the limitation of it being invasive. However, the advances in the radiological imaging techniques would surpass this difficulty, as well helps in coming to a close, if not many times the definitive diagnosis, thus preventing these invasive diagnostic procedures. Aim: To assess the role of triple phase Computed Tomography (CT) in the evaluation of liver lesions by evaluating the enhancing characteristics and comparing the findings with ultrasound, Magnetic Resonance Imaging (MRI), Biopsy and follow-up as applicable during the study period. Materials and Methods: This is a longitudinal prospective study conducted at Kamineni Institute of Medical Sciences, Narketpally, on 60 selected subjects for a period of 12 months, during July 2017 to July 2018. Patients of age more than 20 years of both gender with clinical suspicion or inconclusively diagnosed liver lesions were selected. These patients are evaluated using standard triple phase contrast CT liver protocol on 16 slice multidetector CT scan. The different enhancing patterns were inspected and compared to USG, MRI and Biopsy as applicable. All the collected data were tabulated in Microsoft excel sheet and were analysed in SPSS Software version 21. Results: The study consisted of 60 patients with 35 male and 25 female and assessed a total of 200 individual liver lesions. Out of which, 141 were malignant and 59 benign. Metastasis being the most common (n=113), followed by Hepatocellular Carcinoma (HCA) (n=26) and intrahepatic Cholangiocarcinoma (CCA) (n=2) in malignant lesions and Haemangioma (n=26) was the commonest benign lesion followed by cysts (n=20), abscess (n=10), Focal Nodular Hyperplasia (FNH) (n=2) and adenoma (n=1). In total, there were 112 (56%) hypovascular lesions and 88 hypervascular lesions (44%), with 11 enhancement patterns which are correlated to standards of reference satisfactorily. The study shows triple phase CT is 100% sensitive in diagnosing abscess, simple cysts, FNH and intrahepatic CCA and showed varied sensitivities with other lesions like HCC (sensitivity-79%), Haemangioma (sensitivity-92.3%), Metastasis (sensitivity- 91.1%), however, it showed 100% specificity in diagnosing all the cases when there was typical enhancement pattern for the individual lesion concerned. The four benign enhancement patterns and five malignant enhancement patterns were noted along with hypo/hypo/hypo, hypo/hypo/hyper and hyper/A/A patterns which needs cautious interpretation. Conclusion: We recommend triple phase CT scan as a standard first line procedure with high sensitivity, specificity and accuracy in differentiating benign and malignant liver lesions and avoiding unnecessary biopsies. Hepatic Arterial Phase (HAP) is used in identifying small hypervascular lesions and Porto-Venous Phase (PVP) in detecting small hypovascular lesions. Particularly in HCC, triple phase CT provides additional information of vascular invasions, arterioportal shunts, capsular delineation and vascular road map for pre-surgical evaluation.