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Introduction: Extracutaneous melanomas are rare, aggressive type of tumour, clinically and biologically distinct from their cutaneous counterpart. The two large broad categories of the extracutaneous melanomas are ocular and mucosal subtypes. Melanomas are classically hyperintense on T1 weighted images and hypointense on T2 weighted images due to the paramagnetic effects of melanin and presence of paramagnetic elements. Aim: To describe the Magnetic Resonance Imaging (MRI) findings in primary extracutaneous melanomas at various anatomic sites. Materials and Methods: This was a retrospective study in which 13 cases of primary extracutaneous melanomas were identified from Picture Archiving and Communication System (PACS) archive over a period of eight years (January 2013 - December 2020). Location and morphology of the tumour, signal intensity characteristics in T1 weighted, T2 weighted (hyperintense/ isointense/hypointense to adjacent muscle) and Diffusion Weighted Imaging (DWI) (presence or absence of diffusion restriction) were analysed. Results: The ocular melanomas (n=2) were seen as well-defined small intraocular mass attached to the choroid. The mucosal melanomas of the nasal cavity (n=2), rectum (n=4), vagina (n=3) and cervix (n=2) presented as large intraluminal polypoidal masses. Three categories of MRI appearances emerged in this study. Majority of the cases (n=8) showed hyperintense signals in T1- weighted images and hypointense signals in T2 weighted images (category 1). Diffusion restriction was seen in all cases (n=13) with low Apparent Diffusion Coefficient (ADC) values which ranged from 439-966 mm/sec with an average value of 755 mm/ sec. Conclusion: T1 and T2 shortening are typical of melanoma, the absence of these does not exclude the diagnosis. Although diffusion restriction and low ADC values help in the diagnosis of these tumours, they do not tend to play a specific role in the diagnosis.

Introduction: Anatomical variations of celiac and hepatic arteries are relatively common and impact operative time and technique. Intraoperative identification of the entire course of these vessels can be a challenge due to limited surgical field and increases the chance of iatrogenic injury. Aim: To evaluate and describe the origin and prevalence of retroportal course of hepatic arteries seen in Computed Tomography (CT) angiography in a large series of patients. Materials and Methods: The present retrospective study was conducted in the Department of Radiology, affiliated to a tertiary cancer centre in Southern India. CT angiogram done between January 2020 to June 2021 were included. Total of 326 abdominal CT angiograms were studied for celiac axis variations, variations in the origin and branching pattern of hepatic arteries, trajectory of the hepatic artery and its relation to portal vein. The branching pattern of celiac axis was analysed with adherence to the modified definition of Common Hepatic Artery (CHA) and it was classified as normal/variant/ambiguous. Based on the origin and branching pattern, hepatic arteries were divided into standard/replaced/accessory and classic/variant divisions, respectively. Variant divisions include trifurcation, duplicate or double hepatic artery and late origin of Gastro Duodenal Artery (GDA). Retroportal hepatic arteries under each variation was identified separately and their prevalence calculated. Confidence interval was calculated using simple proportionfrequency analysis open Epi version 3 software. Results: The age of the patients varies from 3 to 83 years (mean age 53.7 years). 207 (63.49%) cases were male and 119 (36.5%) cases were female. 262 (80.37%) cases had a normal celiac axis anatomy. Eight specific types of celiac axis variations were observed in 48 (14.72%) cases. In the remaining 16 (4.91%) cases, the celiac axis anatomy was ambiguous. CHA originated from the celiac axis, Superior Mesentric Artery (SMA) and aorta in 294 (90.18%), 10 (3.07%) and 6 (1.84%) cases respectively. Out of the 52 replaced Right Hepatic Artery (rRHA), 48 (14.72%), 3 (0.92%) and 1 (0.30%) cases had Right Hepatic Artery (RHA) replaced to the SMA, aorta and GDA, respectively. Except for the one rRHA from GDA, all of them had a retroportal course. Classic branching pattern of hepatic artery was seen in 154 (47.24%). Trifurcation, early branching of RHA and early branching of LHA were found in 49 (15.03%), 4 (1.22%) and 8 (2.45%) respectively. 63 (70%) cases of variations in hepatic artery origin, 15 (16.67%) cases of variations in hepatic artery branching and 12 (13.33%) cases of variations in celiac axis contributed to a total of 90 cases with retroportal hepatic artery. Prevalence of retroportal hepatic artery in the present study is 27.61% (confidence interval 22.82- 32.8) and the most common cause was aberrant RHA origin. Conclusion: Knowledge about the origin and prevalence of retroportal course of hepatic artery will help the surgeon to approach it systematically. Preoperative knowledge of the variations in origin and branching patterns and its influence on the trajectory will help in a better intraoperative identification of these variant vessels.