A Study of Anatomical Pattern of Inferior Phrenic Artery using Multidetector CT

Abstract

Introduction: Inferior Phrenic Artery (IPA), though a small artery, is important from several points of view. Apart from being arterial supply to normal structures, it is also involved in many pathological conditions such as tumours, haemoptysis, gastroesophageal bleeding and traumatic conditions where interventional radiology or surgery play an important role in management. A preprocedure idea about variations in its anatomical pattern may help better treatment planning and minimise morbidity. Aim: To study variations in anatomical pattern of IPA in terms of vessel of origin, vertebral level of origin and diameter of IPA using Multidetector Computed Tomography (MDCT). Materials and Methods: The present study was a cross-sectional study conducted in Department of Radiodiagnosis, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India. A retrospective analysis of CT angiography or Triple phase CT abdomen studies of 200 adult patients (M:F 119:81) performed during December 2020 to April 2021 was done to look for anatomical pattern variations in IPA. Vessel of origin and level of origin were recorded. Diameters of IPAs were also recorded and statistical analysis was done. Results: Common Inferior Phrenic Artery (CIPA) was seen in 23% cases, with independent Right and Left Inferior Phrenic artery (RIPA and LIPA) in remaining 77%. Vessels of origin for CIPA were aorta (n=27; 58.7%), celiac trunk (n=16; 34.8%) and right Main Renal Artery (right MRA) (n=3; 6.5%); for RIPA, celiac trunk (n=69; 44.8%), aorta (n=57; 37.01%), right MRA (n=23;14.94%), Left Gastric Artery (LGA) (n=5; 3.25%), and for LIPA, celiac trunk (n=97; 63%), aorta (n=53; 34.4%), left MRA (n=2; 1.3%) and LGA (n=2; 1.3%), respectively. Level of origin from aorta for RIPA was L1>T12>T12/L1 disc>others; LIPA, T12>T12/L1>L1>others; celiac trunk, T12>L1>T12/L1 disc>others. Mean diameters of apparently normal RIPA and LIPA were 1.75 mm and 1.76 mm, respectively. Conclusion: The most common vessels of origin for CIPA, RIPA and LIPA were abdominal aorta (58.7%), celiac trunk (44.8%) and celiac trunk (63%), respectively. The predominant vertebral levels of origin for CIPA, RIPA and LIPA arising from aorta were T12, L1, and T12 respectively, and for celiac trunk T12. The mean diameter of IPA was found to be greatest in cirrhotic group followed by chronic pancreatitis and apparently normal IPA group, but not statistically significant. These can be efficiently and readily demonstrated by CT angiography or arterial phase of multiphasic CT study.