Mass General Hospital
NOVEMBER 2011
ISSUE 41


MRI of Partial Anomalous Pulmonary Venous Return - Scimitar Syndrome
Gladwin Hui, MD; Jonathan Beaudoin, MD; Wilfred Mamuya, MD, PhD, and Suhny Abbara, MD

Clinical History
A remote chest radiograph in a 75-year-old patient demonstrated slight rightward shift of the mediastinum. The patient had been asymptomatic and stable for many years. MRI was ordered to investigate for possible anatomic variant prior to non-cardiac surgery.

Findings
Cardiac MRI demonstrated an abnormal vessel draining the right middle lobe medial segment as well as the right lower lobe (Figure 1-4). The vessel coursed inferiorly and drained into the IVC at the level of the diaphragm, consistent with Scimitar Syndrome. The left common trunk pulmonary vein and the right superior pulmonary vein drained normally into the left atrium. There was also mild right lung volume loss or hypoplasia. In addition, there was an incidental double SVC (superior vena cava), with the left sided IVC (inferior vena cava) draining normally into the coronary sinus.


Figure 1


Figure 2


Figure 3

Figure 4

(Click on image to enlarge)

Figure 1: Axial SSFP (steady state free precession) MR demonstrates anomalous pulmonary vein (Scimitar vein) draining into IVC.

Figure 2:
Coronal reformat of gadolinium enhanced MRA.

Figure 3:
Maximum intensity projection from gadolinium enhanced MRA.

Figure 4:
3D volume rendered reformat demonstrates anomalous pulmonary vein draining inferiorly towards the IVC at the level of the diaphragm.  It courses along the right heart border.


Discussion
Partial anomalous pulmonary venous return (PAPVR) refers to a type of congenital vascular anomaly where one or more pulmonary vein drains not into the left atrium, but instead into the SVC, IVC, right atrium, coronary sinus, hepatic veins or portal veins.  When the pulmonary vein drains into the IVC, it is also called Scimitar Syndrome, named after the Turkish sword for its curvilinear opacity adjacent to the right heart border on a chest radiograph.  Physiologically, Scimitar Syndrome represents a left to right shunt. Most patients are either minimally symptomatic or asymptomatic. The treatment is usually conservative.

Scimitar Syndrome is also known as hypogenetic Lung Syndrome,  because it is often associated with right lung hypoplasia. Imaging often reveals mediastinal shift towards the right, as in this patient. Other documented associations include atrial septal defect, pulmonary artery hypoplasia and sequestration.

CT and MRI are both excellent, noninvasive means to clearly delineate the anatomy and course of PAPVR and Scimitar syndrome. MR has the added advantage of being free of radiation.  MRI can be performed either without or with gadolinium. Gadolinium-enhanced MRA, can demonstrate the anomalous draining pulmonary vein with superb quality.


REFERENCES
1.

Daltrol P., et al.  CT of Congenital Lung Lesions in Pediatric Patients. AJR 2004; vol. 183 no. 5, 1497-1506

2. Gavazzi E., et al. Scimitar Syndrome Comprehensive, Noninvasive Assessment With Cardiovascular Magnetic Resonance Imaging. Circulation 2008; 118: e63-e64
3. Konen E., et al. Congenital Pulmonary Venolobar Syndrome: Spectrum of Helical CT Findings with Emphasis on Computerized Reformatting. RadioGraphics 2003; 23, 1175-1184
4. Wang Z., et al. Cardiovascular Shunts: MR Imaging Evaluation. RadioGraphics 2003; 23, S181-S194

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Editors:
Suhny Abbara, MD
MGH Department of Radiology
Wilfred Mamuya, MD, PhD
MGH Department of Cardiology

Phone: 617-726-5954