408 Copyrights © 2014 The Korean Society of Radiology

INTRODUCTION

There is considerable variation in the branching patterns of the lobar segmental and subsegmental pulmonary artery branches. Most of the variants are clinically silent (1) but some specific variants, such as the pulmonary artery arising from the systemic artery or the right lower lobe medial basal segmental artery arising from the right main pulmonary artery, can be clinically significant because of the surgical risk of vessel injury (2). In this report, we describe an unusual anatomical variant of the left posterior basal segmental pulmonary artery arising from left main pulmonary artery.

CASE REPORT

A 52-year-old man visited our hospital due to fatigue and he was diagnosed with acute myelogenous leukemia. Before he re-ceived chemotherapy, he developed a fever and pneumonia. He underwent a chest computed tomography (CT) scan with 5-mm

section thickness using a multidetector CT scanner (Aquilion 64, Toshiba Medical Systems, Tokyo, Japan). The images were acquired within a single breath hold after injection of the con-trast medium (Iobrix 350; injection rate, 2.2 mL/s; volume, 100 mL). Three-dimension reconstruction images were acquired with commercial software (Aquarius iNtuition, ver. 4.4.7, Ter-arecon, Inc., Foster City, CA, USA).

The CT scan revealed consolidation in the left lung, so we considered bacterial pneumonia. Incidentally, the CT identified an unusual anatomical variant of the left posterior basal seg-mental pulmonary artery (A10) (Fig. 1). A normal left lower lobe posterior basal segmental artery arising from the pars basa-lis was not noted. Instead, an artery supplying the left posterior basal segment arose from the left main pulmonary artery as its first branch, proximal the left lower lobar pulmonary artery. This abnormal artery’s course was under the lower lobar bron-chus and reached the left posterior basal segment. There was no abnormal finding in the bronchi or lung parenchyma and the venous drainage was apparently normal.

Case ReportpISSN 1738-2637 / eISSN 2288-2928J Korean Soc Radiol 2014;70(6):408-410http://dx.doi.org/10.3348/jksr.2014.70.6.408

Received October 25, 2013; Accepted April 24, 2014Corresponding author: Mi-Jin Kang, MDDepartment of Radiology, Sanggye Paik Hospital, Inje University College of Medicine, 1342 Dongil-ro, Nowon-gu, Seoul 139-707, Korea.Tel. 82-2-950-1182 Fax. 82-2-950-1220E-mail: s2621@paik.ac.kr

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distri-bution, and reproduction in any medium, provided the original work is properly cited.

To avoid vessel injury during minimally invasive surgery of the lung, exact knowl-edge of the pulmonary vasculature is important to surgeon. In this report, we pres-ent the case of unusual anatomical variant of the left posterior basal segmental pulmonary artery, arising from the left main pulmonary artery. This anomaly is rare but easily overlooked during interpretation of CT scans, potentially resulting in seri-ous vessel injury during minimally invasive surgery.

Index termsAnatomical Variant Pulmonary ArteryCT Finding

Unusual Anatomical Variant of the Left Posterior Basal Segmental Pulmonary Artery: CT Findings1

폐의 좌하엽 후기저분절 동맥의 드문 해부학적 변이: 단층촬영 소견1

Young-Seon Kim, MD1, Mi-Jin Kang, MD1, Myeong Ja Jeong, MD1, Jae Hyung Kim, MD1, Ji Hae Lee, MD1, Han Bee Lee, MD1, Kyung Eun Bae, MD1, Tae Kyung Kang, MD2

Departments of 1Radiology, 2Emergency Medicine, Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea

Young-Seon Kim, et al

409jksronline.org J Korean Soc Radiol 2014;70(6):408-410

about the detailed anatomy of the pulmonary vessels has be-come important in avoiding surgical risks of vessel injury be-cause of the difficulties associated with the limited field of view.

In this report, we describe the case of an unusual anatomical variant of the left posterior basal segmental pulmonary artery, arising from left pulmonary artery, as its first branch. Thus, it could be called a mediastinal basal artery.

The mediastinal artery was first described in 1973 by Le Brig-and (5), as the first branch of the pulmonary artery emerging from the mediastinum. According to the previous literature, the majority of mediastinal arteries supply the lingular segment (6-8), the so-called mediastinal lingular artery.

A mediastinal basal artery is extremely rare, and only a few cas-es have been reported (6-10). According to previous reports, me-diastinal basal arteries have been characterized supplying multiple segments, such as A8 + 9 (6), A5 + 8 + 9 + 10 (7), A7 + 8 + 9 + 10 (8), A8 + 9 (9), and A9 + 10 (10). However, to our knowledge, there is no previous report of a mediastinal basal artery supply-ing only the posterior basal segment (A10).

The clinical significance of these mediastinal arteries has in-

DISCUSSION

In normal adult human anatomy, the main pulmonary artery arises from the right ventricular outflow tract (3). Then, it passes to the left of and posterior to the aorta and branches into right and left pulmonary arteries. The right pulmonary artery divides into two lobar branches at the root of the right lung (4). The left pulmonary artery courses over the left main bronchus and pen-etrates the root of the left lung, where the artery divides into two lobar branches (4). They course downwards, along the bronchi, to the subsegmental level.

Segmental and subsegmental pulmonary arteries generally parallel the segmental and subsegmental bronchi and run along-side them. Thus, the segmental arteries are named according to the bronchopulmonary segments that they feed. However, there is considerable variation in the branching patterns of the pul-monary artery branches. Moreover, many of these variations in pulmonary arteries are overlooked, because they are clinically silent (1). Today, with development of surgical techniques such as video-assisted thoracoscopic surgery (VATS), knowledge

Fig. 1. A 52-year-old man with an incidentally detected unusual anatomical variant of the left posterior basal segmental pulmonary artery. A-E. Serial contrast enhanced axial chest CT scans show an anomalous vessel (arrows), directly arise from the posterior aspect of the left main pulmonary artery, anterior to the left main bronchus. F, G. Coronal maximum intensity projection image (F) and posterior oblique coronal volume rendered images (G) show an artery supplying left posterior basal segment (arrows), directly arise from left main pulmonary artery before branching upper lobar artery.Note.-Ao = ascending aorta, BT = truncus basalis, LB = left main bronchus, LPA = left pulmonary artery, PA = pulmonary artery

E

A

F

B

GG

C D

Unusual Anatomical Variant of the Left Posterior Basal Segmental Pulmonary Artery

410 jksronline.orgJ Korean Soc Radiol 2014;70(6):408-410

4.CastañerE,GallardoX,RimolaJ,PallardóY,MataJM,Per-

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(tomeIII).Paris:MassonetCie,1973:304-305

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AnnThoracSurg2012;94:e115-e116

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lungcancerwithanextremelyrarebranchingpatternof

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creased with development of minimally invasive surgery. Yama-da et al. (2) noted a surgical risk to the right medial basal seg-mental pulmonary artery (A7) while dividing the right minor fissure during VATS segmentectomy. They detected this varia-tion before surgery on CT; thus they could avoid vessel injury.

We describe a case of a mediastinal basal artery, supplying posterior basal segment of left lower lobe. It is important for the radiologist to be familiar with the CT appearance of various pul-monary artery anomalies to avoid vascular injury during mini-mally invasive surgery.

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폐의 좌하엽 후기저분절 동맥의 드문 해부학적 변이: 단층촬영 소견1

김영선1 · 강미진1 · 정명자1 · 김재형1 · 이지혜1 · 이한비1 · 배경은1 · 강태경2

폐의 최소침습적 수술을 시행할 때 혈관의 손상을 피하기 위해서는 흉부외과 의사가 폐혈관의 정확한 해부학을 아는 것

이 매우 중요하다. 본 증례에서는 좌하엽 후기저분절 동맥이 좌폐동맥에서 직접 분지하는 드문 해부학적 변이에 대해 보

고하고자 한다. 이러한 변이는 드물지만 단층촬영 판독시에 쉽게 간과될 수 있으며 폐의 최소침습적 수술 전에 이러한 변

이를 알지 못한다면 심각한 혈관 손상을 일으킬 수 있을 것이다.

인제대학교 의과대학 상계백병원 1영상의학과, 2응급의학과