Clinical Imaging

Use of multidetector CT angiography and 3D postprocessing in

a case of pulmonary sequestration

Alberto Clemente, Aldo Morra4

Department of Radiology, Euganea Medica, Via Colombo 13, I-35020 Albignasego [PD], Italy

Received 7 December 2006; accepted 22 December 2006

Abstract

Pulmonary sequestration is a pulmonary malformation in which a portion of nonfunctioning bronchopulmonary tissue is separated from

the rest of the lung parenchyma. We report the case of a 48-year-old woman with history of chronic pneumonia, studied with computed

tomography and in whom we obtained three dimensional evaluation of the pathological structures.

D 2007 Elsevier Inc. All rights reserved.

Keywords: CT angiography; Bronchopulmonary sequestration; Congenital anomalies

1. Introduction

Pulmonary sequestration is a rare malformation charac-

terized by a mass of nonfunctioning lung tissue and

vascularized by an aberrant systemic artery. Most patients

are asymptomatic, but some, with concurrent cardiac

anomalies or severe type of pulmonary atresia or hypopla-

sia, may have clinical symptoms at an early age.

The evidence of nonfunctional embryonic lung tissue

lying within a normal pulmonary visceral pleura, with no

communication with normal bronchial system and sup-

plied by an aberrant systemic artery, is diagnostic for

pulmonary sequestration.

Traditionally, angiography has been the imaging proce-

dure of choice for the demonstration of vascular anomalies.

However, the introduction of multidetector computed

tomography (MDCT), combined with the use of advanced

postprocessing graphic workstations, allowed an improved

delineation of the complex and of the variable anatomic

abnormalities seen in patients with pulmonary sequestra-

tion, and it permitted also the identification of abnormal

pulmonary and systemic vessels as well as tracheobron-

chial anomalies.

0899-7071/07/$ – see front matter D 2007 Elsevier Inc. All rights reserved.

doi:10.1016/j.clinimag.2006.12.028

4 Corresponding author. Tel.: +39 049 804 4836; fax: +39 049 804

4801.

E-mail address: aldo.morra@euganeamedica.it (A. Morra).

We report a case of intralobar pulmonary sequestration in

which we obtained accurate information essential for its

diagnosis and for the preoperative evaluation of the patient.

2. Case report

A 48-year-old woman, with a reported history of

pulmonary tuberculosis at the age of 20 years, presented

with chronic pneumonia, productive cough, and fever. A

chest radiograph showed an area of increased opacity in

the right lower lobe simulating pneumonia. The patient

underwent antibiotic therapy, but after a week, no clinical

improvement was achieved. A computed tomographic (CT)

scan without contrast medium was performed to evaluate

the presence of bronchiectasis. A mass located in the right

middle-basal hemithorax, in the paravertebral and retro-

cardiac areas, was demonstrated, inducing the use of

contrast medium for a complete definition of the patho-

logic findings.

A postcontrast CT was performed using a 16-row MDCT

scanner (LightSpeed 16, General Electric Medical System,

Milwaukee, WI, USA), obtaining these parameters: cranio-

caudal acquisition, slice thickness 1.25 mm, table increase

27.50 mm (high speed), tube voltage 120 kV, tube current

250 mA, tube rotation 800 ms, and 120 ml of nonionic

iodinated contrast agent (350 mg I/ml) injected intrave-

nously at 3 ml/s, followed by a 50 ml saline chaser bolus via

a catheter placed into the cubital vein.

31 (2007) 210–213

Fig. 1. (A and B) Axial CT at the level of the lung bases showing a heterogeneous consolidation with mild enhancement of tissue septa that separate cyst-like

structures within the lesion, and a large vessel originating from the thoracic descending aorta (arrow).

A. Clemente, A. Morra / Clinical Imaging 31 (2007) 210–213 211

The image data sets were evaluated and processed on an

independent workstation using Advantage for Windows 4.3

(General Electric Medical System, Milwaukee, WI, USA);

there, multiplanar reformatted (MPR), maximum intensity

projection (MIP), and volume-rendered (VR) images were

obtained to produce images for soft-copy display and hard-

copy printout.

The examination showed a discrete central hypodense

mass located in the right costovertebral sulcus, with central

cystic changes and necrotic–colliquative components, and a

large vessel arising from the thoracic descending aorta (Figs.

1A and B; 2A and B). MPR (Figs. 2A, 3A and B), MIP (Fig.

2B), and 3D VR images (Fig. 4A–C) clearly showed these

anomalies and were helpful in identifying the venous return

Fig. 2. (A and B) Coronal MPR and coronal MIP showing the supplying artery aris

the solid mass at the base of the right lung (arrows).

draining into the systemic right circulation through the

azygos–hemiazygos system.

3. Discussion

Pulmonary sequestration is a relatively rare disorder

classified as either intralobar or extralobar [1,2]. It is defined

as a segment of lung parenchyma that is separated from its

tracheobronchial tree and is supplied with blood from a

systemic rather than a pulmonary artery lying within normal

pulmonary visceral pleura [3,4]. The intralobar sequestra-

tion accounts for 75% of pulmonary sequestration; in 98%

of the cases, is located in lower lobes; and in the majority of

cases (58%), occurs on the left side.

ing from the thoracic aorta and coursing downwards into the chest to supply

Fig. 3. (A and B) Multiplanar curved reformatted view, demonstrating the venous drainage of the lesion through the hemiazygos–azygos system (arrows).

Fig. 4. (A) Schematic drawing of the vascular peduncle (right arrow), and the lung sequestration (left arrow). (B) 3D VR image of the vascular peduncle arising

from the descending aorta (arrowhead with ball) and of the venous drainage (white arrows). (C) 3D VR image of the lung sequestration (arrow).

A. Clemente, A. Morra / Clinical Imaging 31 (2007) 210–213212

A. Clemente, A. Morra / Clinical Imaging 31 (2007) 210–213 213

Pulmonary sequestration is a malformation which is an

uncommon cause of nonresolving or recurrent pneumonia.

Although most patients are asymptomatic, some with

concurrent cardiac anomalies or with severe forms of

pulmonary atresia or hypoplasia may have clinical symp-

toms at an early age. Surgical intervention may be required

in selected cases, such as intractable infection, hemopthysis

and congestive heart failure, or hypertension due to

excessive shunting [5,6]. In the suspected case of pulmonary

sequestration, plain chest radiographs are usually nonspe-

cific, showing an ill-defined consolidation simulating a

pneumonia, or show a soft tissue mass with well- or ill-

defined borders [7].

CT of the chest usually shows a discrete mass in the

posterior- or medial–basal segment of the lower lobe, with

or without cystic changes, as in our case. Absence of

communication between the lung mass, the normal bron-

chial system, and the presence of a supply systemic artery

are diagnostic for pulmonary sequestration. The diagnosis of

pulmonary sequestration traditionally requires arteriography

to identify abnormal systemic vessels feeding the abnormal

portion of the lung [6,8]. Previous studies, performed with

earlier generations of CT scanners, showed that the

procedure was helpful in the evaluation of congenital

pulmonary venolobar syndrome [9] but, in many cases,

could not demonstrate the anomalous vessels.

The recent introduction of multisection helical CT,

combined with the use of advanced postprocessing graphic

workstation, allows improved delineation of the anomaly

and the variable abnormalities seen in patients with

pulmonary sequestration [1]. This information is essential

for an accurate diagnosis and for the preoperative evaluation

of the affected patient.

Usually, the blood supply comes from the descending

thoracic aorta, but in about 20% of the cases, it comes from

the upper segment of the abdominal aorta, the celiac artery,

or the splenic artery [4]. Angiography can demonstrate the

pulmonary venous drainage of the intralobar sequestration,

which, in 95% of the cases, occurs through the pulmonary

veins of the parental lobe into the left atrium [7,8], while in

5% of the cases, it drains into the systemic circulation

through the hemiazygos–azygos system, into the intercostal

veins, or superior vena cava toward the right atrium [10,11].

In rare cases, the lesion may drain into a branch of the

pulmonary artery, joining antegrade arterial flow into the

normal lung parenchyma.

In our case, the vascular supply arose from the

descending thoracic aorta, while the venous drainage was

connected with the superior vena cava through the hemi-

azygos–azygos system.

MPR, MIP, and VR were very helpful in showing a

complete and immediate representation of the anatomical

details of sequestration, the aberrant artery and the venous

return. Images obtained with 3D elaboration techniques

supplied anatomical detailed information that was needful

and quite imperative in the planning of a better therapeutic

treatment, while spiral CT allowed the definition of both

nature of the pathologic alterations and the associated

vascular abnormalities, without the aid of angiography.

Using these reconstructed images we were able to

formulate a complete anatomical diagnosis and present it

to the referring physician.

4. Conclusion

Pulmonary sequestration is a rare acquired disorder—the

intralobar, more common, is located on the left side and

occurs in the lower lobes—or congenital, intralobar or

extralobar. Its diagnosis is characterized by the presence of

pulmonary tissue that does not communicate with the

normal tracheobronchial tree but receive its arterial supply

from an anomalous systemic artery, most frequently from

the thoracic aorta, the celiac artery, or the splenic artery. An

intralobar sequestration is located within the normal lung

and its pleural cover. The most common clinical manifes-

tation is infection. The diagnosis of pulmonary sequestration

enforces the surgical exeresis to prevent the inevitable

infective complications.

Multisection helical CT is a helpful diagnostic proce-

dure in the preoperative evaluation of patients with

suspected congenital pulmonary sequestration, as it allows

a detailed assessment of vascular, tracheobronchial and

pulmonary abnormalities with a single short, noninvasive,

and painless procedure.

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