| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Case Report |
1 Both authors: Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins Medical Institutions, 600 N. Wolfe St., Baltimore, MD 21287.
Received March 16, 2001;
accepted after revision June 7, 2001.
Address correspondence to E. K. Fishman.
Introduction
 Top Introduction Case ReportDiscussionReferences |
|---|
|
TopIntroductionCase ReportDiscussionReferences |
|---|
The arteriovenous malformations in the patient's left chest had been detected 7 years previously by chest radiography, conventional axial CT, and conventional angiography (Figs. 1A,1B,1C). The first arteriovenous malformation had been documented as a single lesion in the lingula. Its complex connections were unclear on CT, but on angiography the lesion was characterized by systemic arterial supply from the celiac axis with venous drainage to the left pulmonary artery (Figs. 1A and 1B). The second lesion was identified in the left basilar region; its supply and drainage could not be explained by axial CT, but angiography showed supply from two intercostal arteries (Fig. 1C). Venous drainage could not be established. Oxygen sampling of the left pulmonary artery blood confirmed a left-to-right shunt. At that time, the patient was well, and therapeutic intervention was decided against. A series of infections since then, including osteomyelitis, had prompted reevaluation with a view to therapy.
|
|
|
Imaging was performed on a multidetector CT scanner with three-dimensional volume rendering (Plus 4 Volume Zoom; Siemens Medical Systems, Iselin, NJ) (Figs. 1D,1E,1F). The thorax and upper abdomen were imaged with 1-mm collimation and 1.25-mm slice thickness, using 1-mm data reconstructions with a pitch of 6 (defined as travel per gantry rotation / slice collimation). The patient was given 750 mL of water orally and 125 mL of IV contrast material (Omnipaque 350 [iohexol]; Nycomed Amersham, Princeton, NJ) at a rate of 3 mL/sec with a scan delay of 25 sec. Three-dimensional volume rendering was subsequently performed on a proto-type Siemens 3D Virtuoso workstation (Siemens Medical Systems).
|
|
|
Two vascular malformations were seen. A large vascular malformation in the lingula (Figs. 1D and 1E) was fed by a large tortuous systemic artery that ran cephalad from its origin below the diaphragm at the celiac axis (Fig. 1E). Venous drainage was by a large straight vessel directed posterosuperiorly to the left pulmonary artery just beyond its upper lobe branches. A smaller parallel venous drainage to the left superior pulmonary vein was also identified (Fig. 1D). The other vascular malformation was seen on the left posterior chest wall, fed by three intercostal branches with venous drainage by a small vessel to the distal left lower lobe pulmonary artery (Fig. 1F). The main and branch pulmonary arteries were otherwise normal, and no evidence of congenital heart disease was found. No lung airway or parenchymal abnormalities were seen. The patient was referred for assessment for embolic coil therapy.
|
TopIntroductionCase ReportDiscussionReferences |
|---|
Along this continuum of disease are normally sited systemic arteries delivering oxygenated blood to a normal lung (e.g., normal bronchial arteries to the lung, patent ductus arteriosus, pulmonary atresia, or coronary fistula) and abnormal systemic arteries delivering blood to an abnormal lung (e.g., sequestration or congenital adenomatous malformation). Pulmonary arteriovenous malformation represents one end of this classification scheme with abnormal arteries to normal lung, and it may be considered along with conditions such as isolated systemic supply to normal lung and truncus arteriosus. Iatrogenic surgical anastamoses are best considered under a separate scheme.
Venous drainage may be to pulmonary veins (as in arteriovenous malformation, intralobar sequestration, or total anomalous pulmonary venous return) or to systemic veins (as in scimitar syndrome or extralobar sequestration). Venous drainage to pulmonary arteries is unusual, and a lesion with concurrent pulmonary venous outflow has not been described to our knowledge.
The developing lung buds are richly supplied by a vascular plexus formed by the primitive postbranchial arteries arising from paired dorsal aortas [3]. These postbranchial vessels are present at birth and disappear with the maturation of the pulmonary arteries from the sixth aortic arches. One consideration for systemic artery supply to this patient's arteriovenous malformation is that it represents the persistence of these embryonic systemic artery collaterals to the pulmonary arteries. This theory has been suggested in the pathogenesis of isolated systemic supply to a normal lung.
Pulmonary arteriovenous malformations may be considered simple or complex; they may be single or multiple. Some are congenital, either manifesting as part of a syndrome (hereditary hemorrhagic telangiectasia) or as isolated anomalies. Some are acquired from trauma and chronic inflammation [4], and it has been suggested that systemic arterialization of a normal lung may represent inflammation-induced hypertrophy of vessels in the inferior pulmonary ligament [5]. Thus it is interesting to consider in this patient whether the vascular malformation is in some way related to his agammaglobulinemic state and repeated respiratory infections since childhood. To our knowledge, no reports of such an association exist in the literature. Systemic supply to pulmonary arteries has been noted in the setting of cyanotic obstructive right heart lesions such as tetralogy of Fallot, and systemic supply to pulmonary arteriovenous malformations may be induced by treatments that cause local ischemia [6].
The majority of pulmonary arteriovenous malformations represent a right-to-left shunt. Patients may suffer dyspnea, cyanosis, or clubbing, and documented complications include paradoxical emboli, hemoptysis, and brain abscess. Because the dominant venous outflow in this patient was to the left pulmonary artery with smaller drainage to the left pulmonary vein, the systemic supply dictated a larger left-to-right shunt with a smaller left-to-left connection. Therefore, our patient was not cyanotic, despite having a large pulmonary arteriovenous malformation.
Selective embolization is considered the first-line treatment for pulmonary arteriovenous malformations, and creation of a "roadmap" before the procedure is imperative. Failure to identify systemic arterial supply is a potential source of recurrence of arteriovenous malformations after an apparently successful embolization [6].
Conventional CT is a sensitive method to establish the diagnosis of pulmonary arteriovenous malformation. We favor it over MR imaging because CT can simultaneously reveal the commonly associated bronchopulmonary abnormalities. Moreover, multidetector CT and three-dimensional volume rendering can deliver high-quality angiograms that show multiple and complex arteriovenous malformations in a way that obviates the need for diagnostic conventional angiography unless flow direction and pressure sampling are a requirement. In this patient, multidetector CT with 0.5-sec gantry rotation and high pitch allowed z-axis coverage of the full extent of both lesions, from the upper thorax to the upper abdomen, in a single breath-hold and without compromise of in-plane resolution. Three-dimensional CT imaging with shaded surface display has been shown reliable in revealing arteriovenous malformation angioarchitecture [7]. The volume-rendered technique preserves all the data acquired, unlike a threshold technique, and may have helped us see smaller branch vessels in this patient [6, 8].
One of the fundamental advantages of volume-rendered CT over conventional angiography is that one may create with a single bolus of contrast a series of detailed, unique maps of tortuous pulmonary arteriovenous malformations, with images tailored to best advantage after data acquisition and with the best orientation already deduced. Seven years ago, axial CT in this patient required the complimentary use of conventional angiography for vascular malformation mapping. Today, with volume-rendered CT angiography, the need for invasive mapping may be questioned.
|
TopIntroductionCase ReportDiscussionReferences |
|---|
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
 |
|
  M. J. Siegel Multiplanar and Three-dimensional Multi-Detector Row CT of Thoracic Vessels and Airways in the Pediatric Population Radiology, December 1, 2003; 229(3): 641 - 650. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
