# Inferior Phrenic Artery Variations and a Novel Classification of Aortic and Non-aortic Origins: An Observational CT Angiographic Study

## TL;DR

This study examines variations in the inferior phrenic arteries using CT scans and proposes a new classification system for their origins.

## Contribution

The study introduces a novel classification of inferior phrenic artery variations based on aortic and non-aortic origins.

## Key findings

- 44.34% of subjects showed variations in inferior phrenic artery origins.
- 64.53% of observed arteries originated from the aorta, with 13.74% having displaced origins.
- 35.47% of arteries were of non-aortic origin, classified as misplaced arteries.

## Abstract

Background and aim

The inferior phrenic arteries (IPAs) usually originate from the abdominal aorta as collateral branches and are small arteries that supply the diaphragm. Related pathologies include hemoptysis, bleeding during surgery or trauma, Mallory-Weiss tear, gastroesophageal cancer, and collateral blood supply to hepatocellular carcinoma. Knowledge about variations involving these arteries is important for clinicians, radiologists, and surgeons. This study aims to observe variations in the origin of IPAs and propose a novel classification of aortic and non-aortic origin arteries based on CT angiographic findings.

Materials and methods

The study was conducted in the Department of Anatomy in collaboration with the Department of Radiodiagnosis. Computerized tomographic angiograms of 100 subjects aged 15-70 years were retrospectively collected and reviewed after applying inclusion and exclusion criteria. The site and pattern of origin of the IPAs were observed on reconstructed CT images. The arteries were grouped according to the type of variation observed, and the prevalence of specific variations was estimated and compared on the basis of gender. A novel classification of arterial variants was also proposed.

Results

IPA anatomy was studied in 100 subjects. Instead of the expected 200 IPAs, 203 arteries were observed due to the presence of three accessory arteries. Out of these 203 arteries, 131 (64.53%) were of aortic origin - 113 (86.26%) with normal origin and 18 (13.74%) with variant (displaced) origin. The remaining 72 arteries (35.47%) were of non-aortic origin (misplaced arteries). Thus, two types of arterial variations were identified: displaced arteries (variant aortic origin) and misplaced arteries (non-aortic origin).

Conclusions

The total prevalence of variations in IPAs was found to be 44.34%. Precise knowledge of these variations is crucial for medical management and before surgical or interventional treatments. The study uniquely reports the displaced variants of IPAs and proposes a classification into different types based on the pattern of origin.