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MR Imaging and CT of Vascular Anomalies and Connections in Patients with Congenital Heart Disease: Significance in Surgical Planning¹

¹ From the Departments of Radiology (L.B.H., N.H.), Pediatric Cardiology (H.J.I.), and Cardiothoracic Surgery (G.A.C.), Albert Einstein College of Medicine and Montefiore Medical Center, 111 E 210th St, Bronx, NY 10467; and the Division of Pediatric Cardiology, New York Presbyterian Hospital, Children’s Hospital of New York, and Columbia University, New York, NY (J.S.G.). Recipient of an Excellence in Design award for an education exhibit at the 2000 RSNA scientific assembly. Received May 24, 2001; revision requested July 5 and received July 26; accepted July 30. Address correspondence to L.B.H. (e-mail: lharamati@aecom.yu.edu).

	Abstract

Top Abstract LEARNING OBJECTIVES Introduction Materials and Methods Results and Diagnostic... Discussion Conclusions References

 
To plan effective management of congenital heart disease, one needs the clearest understanding of the anatomy. Although echocardiography and angiography are the dominant imaging modalities in patients with congenital heart disease, magnetic resonance (MR) imaging and computed tomography (CT) are valuable noninvasive adjuncts. MR imaging and CT are effective in demonstrating the complex cardiovascular morphology present in congenital heart disease, especially the extracardiac morphology. In patients with tetralogy of Fallot with complex pulmonary artery anatomy, MR imaging and CT are useful in demonstrating the pulmonary artery anatomy, along with the significant aortopulmonary collateral vessels. In the heterotaxy syndromes, patients often have unusual atriovenous connections. MR imaging allows accurate identification of the hepatic, systemic, and pulmonary veins and their relationships to both atria. CT and MR are the imaging modalities of choice in a patient who is thought to have a vascular ring. Treatment of aortic coarctation is usually performed on the basis of typical clinical and echocardiographic findings. In patients with atypical clinical or echocardiographic findings, MR imaging and CT yield helpful information that can change the treatment plan. The enhanced preoperative understanding of congenital heart disease provided by MR imaging and CT simplifies surgical decision making and consequently may improve outcome.

© RSNA, 2002

Index Terms: Aorta, abnormalities, 562.154 • Aorta, stenosis or obstruction, 56.1511 • Heart, abnormalities, 50.1653 • Tetralogy of Fallot, 50.145

	LEARNING OBJECTIVES

Top Abstract LEARNING OBJECTIVES Introduction Materials and Methods Results and Diagnostic... Discussion Conclusions References

 
After reading this article and taking the test, the reader will be able to:

• Describe the complementary role of MR imaging and CT to echocardiography and angiography in evaluation of extracardiac arterial and venous anatomy and connections in patients with congenital heart disease.
  
• Recognize the imaging features specifically helpful in preoperative planning for patients with tetralogy of Fallot, heterotaxy syndrome, vascular ring, and coarctation of the aorta.
  

	Introduction

Top Abstract LEARNING OBJECTIVES Introduction Materials and Methods Results and Diagnostic... Discussion Conclusions References

 
Echocardiography and angiography are the traditional imaging modalities used to diagnose congenital heart disease. Echocardiography with Doppler performs well in defining intracardiac anomalies and estimating hemodynamics. However, it is limited by a small field of view, a variable acoustic window, inability to penetrate air and bone, and difficulty in delineating extracardiac vascular structures in their entirety. Cardiac catheterization and angiography is an invasive modality that yields important hemodynamic data while clearly defining anatomy in vessels that are accessible to catheterization. However, angiography often gives only indirect information regarding venous connections and arterial anatomy distal to high-grade stenosis or atresia. It also uses high doses of ionizing radiation and is limited by the risks inherent to iodinated contrast material.

Therefore, magnetic resonance (MR) imaging and computed tomography (CT) play a valuable role in bridging the gaps created by echocardiography and angiography, specifically with regard to extracardiac arterial and venous anatomy and connections in patients with congenital heart disease. MR imaging and CT can assist in making appropriate decisions in evaluation of and surgical planning for patients who have previously undergone surgical or other interventional cardiac procedures, especially if vascular access is difficult or undesired (1–3).

The direct multiplanar image capability of MR imaging allows precise depiction of the complex and often unexpected cardiac and extracardiac arterial and venous morphologies present. MR imaging also has the advantage of not exposing the patient to ionizing radiation. Rapid image acquisition sequences such as single-shot echo-planar imaging and half-Fourier single-shot turbo spin-echo imaging are continuing to evolve. These advances make MR imaging more practical for sick young patients and lessen the duration of sedation. MR imaging has proved to be effective in diagnosis of coarctation of the aorta, aortic arch anomalies with vascular rings, pulmonary arterial and venous connections, and complex univentricular lesions (4,5).

CT has the advantages of easy availability and very short scanning times. Radiologists have developed a facility for using CT in vascular imaging. Contrast material–enhanced helical CT allows the precise timing necessary for accurate extracardiac arterial and venous vascular imaging. Multiplanar reformation is currently readily available, decreasing the inherent disadvantage of CT image acquisition exclusively in the transaxial plane. The drawbacks of CT include patient exposure to ionizing radiation and the risks of iodinated contrast material. Adjustment of specific technical factors has been shown to minimize the radiation dose in children undergoing CT. Such adjustment includes setting the lowest diagnostic tube current according to patient weight (range, 40–140 mA for chest CT). In addition, doubling the pitch reduces radiation dose by half. A practical standard pitch for single–detector row helical CT in children is 1.5:1 (6).

The decision to image with CT versus MR imaging should be based on institutional equipment, scheduling, and availability as well as the patient’s ability to cooperate. The need to tailor the examination to answer the specific questions being asked may also guide the choice of CT versus MR imaging.

In this article, we describe our experience with four types of complex congenital heart disease in which the use of MR imaging and CT provided enhanced anatomic delineation and therefore played an important role in surgical planning and assessment.

	Materials and Methods

Top Abstract LEARNING OBJECTIVES Introduction Materials and Methods Results and Diagnostic... Discussion Conclusions References

 
We retrospectively reviewed all chest MR images and CT scans obtained to evaluate congenital cardiovascular anatomy between December 1998 and March 2001 within a single institution. The findings in these patients had been reviewed, and further specific anatomic information was requested prior to surgery that MR imaging or CT could potentially elucidate. Twenty MR imaging examinations and four CT examinations were performed in 23 patients. One patient was examined with both modalities. The patient population consisted of 14 male patients and nine female patients with a mean age of 5.8 years (range, 6 days to 37 years). The MR imaging and CT results were correlated with results of echocardiography (n = 22), angiography (n = 13), and surgery (n = 14). All MR images were spin echo, T1 weighted, and cardiac gated and were obtained in the axial, sagittal, and coronal planes with a section thickness of 3–5 mm, a gap of 0–1 mm, and four signals acquired. All CT scans were obtained with a single–detector row helical unit by using 3-mm collimation and a pitch of 1.5:1–2:1; the dose of contrast material and the rate of intravenous administration varied according to patient weight. Patients were placed in one of four diagnostic groups based on the indications for imaging: tetralogy of Fallot with complex pulmonary artery abnormalities and aortopulmonary collateral vessels (n = 6), visceral heterotaxy syndromes with complex abnormalities in systemic and pulmonary venous drainage (n = 4), vascular rings (n = 7), and coarctation of the aorta (n = 6).

	Results and Diagnostic Applications

Top Abstract LEARNING OBJECTIVES Introduction Materials and Methods Results and Diagnostic... Discussion Conclusions References

 
Tetralogy of Fallot
Six patients with tetralogy of Fallot were imaged with MR imaging (n = 5) or CT (n = 1). All six patients were also imaged with concurrent echocardiography, and five were imaged with angiography. Five patients had complex pulmonary artery anatomy including discontinuous pulmonary arteries with multiple aortopulmonary collateral vessels arising from the aorta. In addition to depicting the intracardiac anatomy associated with tetralogy of Fallot, the MR and CT images accurately depicted the anatomy of the central pulmonary arteries and the major aortopulmonary collateral vessels (Figs 1, 2), aiding in the creation ofneopulmonary arteries by unifocalization of the major collateral vessels for the three patients who underwent surgery. One patient was evaluated after surgery because echocardiography failed to image the left pulmonary artery. MR imaging demonstrated a patent but reoriented left pulmonary artery.

View larger version (154K): [in this window] [in a new window] [Download PPT slide]   Figure 1a.  Goldenhar syndrome and tetralogy of Fallot in a 17-month-old boy who underwent creation of a modified Blalock-Taussig shunt in infancy. (a) Coronal MR image shows marked right ventricular enlargement and hypertrophy. (b) Axial MR image shows a right aortic arch (Ao) with a large left-sided patent ductus arteriosus (PDA) supplying an isolated left pulmonary artery (LPA) (ie, one not in continuity with the main pulmonary artery). (c) Axial MR image shows marked stenosis of the main pulmonary artery (MPA) and the origin of the right pulmonary artery (RPA). The descending left pulmonary artery (LPA) is large and isolated. Ao = aorta. Surgery involved unifocalization of the nonconfluent pulmonary arteries and repair of the tetralogy of Fallot.

View larger version (152K): [in this window] [in a new window] [Download PPT slide]   Figure 1b.  Goldenhar syndrome and tetralogy of Fallot in a 17-month-old boy who underwent creation of a modified Blalock-Taussig shunt in infancy. (a) Coronal MR image shows marked right ventricular enlargement and hypertrophy. (b) Axial MR image shows a right aortic arch (Ao) with a large left-sided patent ductus arteriosus (PDA) supplying an isolated left pulmonary artery (LPA) (ie, one not in continuity with the main pulmonary artery). (c) Axial MR image shows marked stenosis of the main pulmonary artery (MPA) and the origin of the right pulmonary artery (RPA). The descending left pulmonary artery (LPA) is large and isolated. Ao = aorta. Surgery involved unifocalization of the nonconfluent pulmonary arteries and repair of the tetralogy of Fallot.

View larger version (185K): [in this window] [in a new window] [Download PPT slide]   Figure 1c.  Goldenhar syndrome and tetralogy of Fallot in a 17-month-old boy who underwent creation of a modified Blalock-Taussig shunt in infancy. (a) Coronal MR image shows marked right ventricular enlargement and hypertrophy. (b) Axial MR image shows a right aortic arch (Ao) with a large left-sided patent ductus arteriosus (PDA) supplying an isolated left pulmonary artery (LPA) (ie, one not in continuity with the main pulmonary artery). (c) Axial MR image shows marked stenosis of the main pulmonary artery (MPA) and the origin of the right pulmonary artery (RPA). The descending left pulmonary artery (LPA) is large and isolated. Ao = aorta. Surgery involved unifocalization of the nonconfluent pulmonary arteries and repair of the tetralogy of Fallot.

View larger version (123K): [in this window] [in a new window] [Download PPT slide]   Figure 2a.  Tetralogy of Fallot and pulmonary atresia in a 10-year-old girl. (a) Contrast-enhanced CT scan shows a large ascending aorta that receives the entire cardiac output. The descending aorta gives rise to a large right-sided aortopulmonary (A-P) collateral vessel. A retroaortic left brachiocephalic vein (LBCV) is present. (b, c) Coronal two-dimensional reformation images show two large left-sided aortopulmonary (A-P) collateral vessels supplying the left upper (b) and left lower (c) lung. Ao = aorta. (d) CT scan (lung window) shows the mosaic perfusion pattern consistent with pulmonary atresia. Surgery involved unifocalization of the nonconfluent pulmonary arteries and repair of the tetralogy of Fallot.

View larger version (154K): [in this window] [in a new window] [Download PPT slide]   Figure 2b.  Tetralogy of Fallot and pulmonary atresia in a 10-year-old girl. (a) Contrast-enhanced CT scan shows a large ascending aorta that receives the entire cardiac output. The descending aorta gives rise to a large right-sided aortopulmonary (A-P) collateral vessel. A retroaortic left brachiocephalic vein (LBCV) is present. (b, c) Coronal two-dimensional reformation images show two large left-sided aortopulmonary (A-P) collateral vessels supplying the left upper (b) and left lower (c) lung. Ao = aorta. (d) CT scan (lung window) shows the mosaic perfusion pattern consistent with pulmonary atresia. Surgery involved unifocalization of the nonconfluent pulmonary arteries and repair of the tetralogy of Fallot.

View larger version (160K): [in this window] [in a new window] [Download PPT slide]   Figure 2c.  Tetralogy of Fallot and pulmonary atresia in a 10-year-old girl. (a) Contrast-enhanced CT scan shows a large ascending aorta that receives the entire cardiac output. The descending aorta gives rise to a large right-sided aortopulmonary (A-P) collateral vessel. A retroaortic left brachiocephalic vein (LBCV) is present. (b, c) Coronal two-dimensional reformation images show two large left-sided aortopulmonary (A-P) collateral vessels supplying the left upper (b) and left lower (c) lung. Ao = aorta. (d) CT scan (lung window) shows the mosaic perfusion pattern consistent with pulmonary atresia. Surgery involved unifocalization of the nonconfluent pulmonary arteries and repair of the tetralogy of Fallot.

View larger version (135K): [in this window] [in a new window] [Download PPT slide]   Figure 2d.  Tetralogy of Fallot and pulmonary atresia in a 10-year-old girl. (a) Contrast-enhanced CT scan shows a large ascending aorta that receives the entire cardiac output. The descending aorta gives rise to a large right-sided aortopulmonary (A-P) collateral vessel. A retroaortic left brachiocephalic vein (LBCV) is present. (b, c) Coronal two-dimensional reformation images show two large left-sided aortopulmonary (A-P) collateral vessels supplying the left upper (b) and left lower (c) lung. Ao = aorta. (d) CT scan (lung window) shows the mosaic perfusion pattern consistent with pulmonary atresia. Surgery involved unifocalization of the nonconfluent pulmonary arteries and repair of the tetralogy of Fallot.

View larger version (148K): [in this window] [in a new window] [Download PPT slide]   Figure 3a.  Heterotaxy syndrome, polysplenia, and a double-outlet right ventricle in a 1-year-old boy. (a) Axial MR image shows the side-by-side origins of the aorta (Ao) (posterior, right) and the main pulmonary artery (PA) (anterior, left), both of which arise from the right ventricular outflow tract (RVOT). The left superior pulmonary vein (PV) is seen entering the left-sided atrium. ASept = atrial septum. (b) Coronal MR image shows an unusual configuration of the atrial septum (ASept), which is common in heterotaxy. There is morphologic atrial inversion. Right-sided hepatic veins (HV) enter the right-sided atrium. The coronary sinus is absent. (c) Oblique coronal MR image shows the right superior pulmonary vein (PV) and a left-sided hepatic venous confluence (HV) entering the same right-sided atrium. Surgery consisted of a hemi-Fontan procedure.

View larger version (138K): [in this window] [in a new window] [Download PPT slide]   Figure 3b.  Heterotaxy syndrome, polysplenia, and a double-outlet right ventricle in a 1-year-old boy. (a) Axial MR image shows the side-by-side origins of the aorta (Ao) (posterior, right) and the main pulmonary artery (PA) (anterior, left), both of which arise from the right ventricular outflow tract (RVOT). The left superior pulmonary vein (PV) is seen entering the left-sided atrium. ASept = atrial septum. (b) Coronal MR image shows an unusual configuration of the atrial septum (ASept), which is common in heterotaxy. There is morphologic atrial inversion. Right-sided hepatic veins (HV) enter the right-sided atrium. The coronary sinus is absent. (c) Oblique coronal MR image shows the right superior pulmonary vein (PV) and a left-sided hepatic venous confluence (HV) entering the same right-sided atrium. Surgery consisted of a hemi-Fontan procedure.

View larger version (184K): [in this window] [in a new window] [Download PPT slide]   Figure 3c.  Heterotaxy syndrome, polysplenia, and a double-outlet right ventricle in a 1-year-old boy. (a) Axial MR image shows the side-by-side origins of the aorta (Ao) (posterior, right) and the main pulmonary artery (PA) (anterior, left), both of which arise from the right ventricular outflow tract (RVOT). The left superior pulmonary vein (PV) is seen entering the left-sided atrium. ASept = atrial septum. (b) Coronal MR image shows an unusual configuration of the atrial septum (ASept), which is common in heterotaxy. There is morphologic atrial inversion. Right-sided hepatic veins (HV) enter the right-sided atrium. The coronary sinus is absent. (c) Oblique coronal MR image shows the right superior pulmonary vein (PV) and a left-sided hepatic venous confluence (HV) entering the same right-sided atrium. Surgery consisted of a hemi-Fontan procedure.

View larger version (187K): [in this window] [in a new window] [Download PPT slide]   Figure 4a.  Heterotaxy and a single ventricle in a 4-year-old boy who underwent a bidirectional Glenn procedure. MR imaging was performed to evaluate the pulmonary and hepatic veins before additional corrective surgery. (a) Coronal MR image shows a single ventricle (V) that gives rise to a "tucked" aorta (Ao). The pulmonary artery has been disconnected from the heart and is in continuity with the bidirectional Glenn anastomosis. The coronary sinus is absent. (b) Axial MR image shows bilateral superior venae cavae (SVC) with turbulent flow. Ao = aorta. (c) Axial MR image shows the left superior vena cava (SVC) entering the left pulmonary artery (PA). The right superior vena cava is still proximal to the right pulmonary artery. (d) Sagittal MR image shows a hepatic venous confluence (HV) entering the left atrium (LA). (e) Sagittal MR image shows a second hepatic venous confluence (HV) entering the right atrium (RA), which is anterior to the left atrium (LA). Ao = aorta. (f) Axial MR image shows the right and left superior pulmonary veins (PV) entering the left atrium (LA). There is a large atrial septal defect (double-headed arrow). ASept = atrial septum, RA = right atrium. Surgery involved completion of a Fontan procedure.

View larger version (133K): [in this window] [in a new window] [Download PPT slide]   Figure 4b.  Heterotaxy and a single ventricle in a 4-year-old boy who underwent a bidirectional Glenn procedure. MR imaging was performed to evaluate the pulmonary and hepatic veins before additional corrective surgery. (a) Coronal MR image shows a single ventricle (V) that gives rise to a "tucked" aorta (Ao). The pulmonary artery has been disconnected from the heart and is in continuity with the bidirectional Glenn anastomosis. The coronary sinus is absent. (b) Axial MR image shows bilateral superior venae cavae (SVC) with turbulent flow. Ao = aorta. (c) Axial MR image shows the left superior vena cava (SVC) entering the left pulmonary artery (PA). The right superior vena cava is still proximal to the right pulmonary artery. (d) Sagittal MR image shows a hepatic venous confluence (HV) entering the left atrium (LA). (e) Sagittal MR image shows a second hepatic venous confluence (HV) entering the right atrium (RA), which is anterior to the left atrium (LA). Ao = aorta. (f) Axial MR image shows the right and left superior pulmonary veins (PV) entering the left atrium (LA). There is a large atrial septal defect (double-headed arrow). ASept = atrial septum, RA = right atrium. Surgery involved completion of a Fontan procedure.

View larger version (125K): [in this window] [in a new window] [Download PPT slide]   Figure 4c.  Heterotaxy and a single ventricle in a 4-year-old boy who underwent a bidirectional Glenn procedure. MR imaging was performed to evaluate the pulmonary and hepatic veins before additional corrective surgery. (a) Coronal MR image shows a single ventricle (V) that gives rise to a "tucked" aorta (Ao). The pulmonary artery has been disconnected from the heart and is in continuity with the bidirectional Glenn anastomosis. The coronary sinus is absent. (b) Axial MR image shows bilateral superior venae cavae (SVC) with turbulent flow. Ao = aorta. (c) Axial MR image shows the left superior vena cava (SVC) entering the left pulmonary artery (PA). The right superior vena cava is still proximal to the right pulmonary artery. (d) Sagittal MR image shows a hepatic venous confluence (HV) entering the left atrium (LA). (e) Sagittal MR image shows a second hepatic venous confluence (HV) entering the right atrium (RA), which is anterior to the left atrium (LA). Ao = aorta. (f) Axial MR image shows the right and left superior pulmonary veins (PV) entering the left atrium (LA). There is a large atrial septal defect (double-headed arrow). ASept = atrial septum, RA = right atrium. Surgery involved completion of a Fontan procedure.

View larger version (200K): [in this window] [in a new window] [Download PPT slide]   Figure 4d.  Heterotaxy and a single ventricle in a 4-year-old boy who underwent a bidirectional Glenn procedure. MR imaging was performed to evaluate the pulmonary and hepatic veins before additional corrective surgery. (a) Coronal MR image shows a single ventricle (V) that gives rise to a "tucked" aorta (Ao). The pulmonary artery has been disconnected from the heart and is in continuity with the bidirectional Glenn anastomosis. The coronary sinus is absent. (b) Axial MR image shows bilateral superior venae cavae (SVC) with turbulent flow. Ao = aorta. (c) Axial MR image shows the left superior vena cava (SVC) entering the left pulmonary artery (PA). The right superior vena cava is still proximal to the right pulmonary artery. (d) Sagittal MR image shows a hepatic venous confluence (HV) entering the left atrium (LA). (e) Sagittal MR image shows a second hepatic venous confluence (HV) entering the right atrium (RA), which is anterior to the left atrium (LA). Ao = aorta. (f) Axial MR image shows the right and left superior pulmonary veins (PV) entering the left atrium (LA). There is a large atrial septal defect (double-headed arrow). ASept = atrial septum, RA = right atrium. Surgery involved completion of a Fontan procedure.

View larger version (184K): [in this window] [in a new window] [Download PPT slide]   Figure 4e.  Heterotaxy and a single ventricle in a 4-year-old boy who underwent a bidirectional Glenn procedure. MR imaging was performed to evaluate the pulmonary and hepatic veins before additional corrective surgery. (a) Coronal MR image shows a single ventricle (V) that gives rise to a "tucked" aorta (Ao). The pulmonary artery has been disconnected from the heart and is in continuity with the bidirectional Glenn anastomosis. The coronary sinus is absent. (b) Axial MR image shows bilateral superior venae cavae (SVC) with turbulent flow. Ao = aorta. (c) Axial MR image shows the left superior vena cava (SVC) entering the left pulmonary artery (PA). The right superior vena cava is still proximal to the right pulmonary artery. (d) Sagittal MR image shows a hepatic venous confluence (HV) entering the left atrium (LA). (e) Sagittal MR image shows a second hepatic venous confluence (HV) entering the right atrium (RA), which is anterior to the left atrium (LA). Ao = aorta. (f) Axial MR image shows the right and left superior pulmonary veins (PV) entering the left atrium (LA). There is a large atrial septal defect (double-headed arrow). ASept = atrial septum, RA = right atrium. Surgery involved completion of a Fontan procedure.

View larger version (133K): [in this window] [in a new window] [Download PPT slide]   Figure 4f.  Heterotaxy and a single ventricle in a 4-year-old boy who underwent a bidirectional Glenn procedure. MR imaging was performed to evaluate the pulmonary and hepatic veins before additional corrective surgery. (a) Coronal MR image shows a single ventricle (V) that gives rise to a "tucked" aorta (Ao). The pulmonary artery has been disconnected from the heart and is in continuity with the bidirectional Glenn anastomosis. The coronary sinus is absent. (b) Axial MR image shows bilateral superior venae cavae (SVC) with turbulent flow. Ao = aorta. (c) Axial MR image shows the left superior vena cava (SVC) entering the left pulmonary artery (PA). The right superior vena cava is still proximal to the right pulmonary artery. (d) Sagittal MR image shows a hepatic venous confluence (HV) entering the left atrium (LA). (e) Sagittal MR image shows a second hepatic venous confluence (HV) entering the right atrium (RA), which is anterior to the left atrium (LA). Ao = aorta. (f) Axial MR image shows the right and left superior pulmonary veins (PV) entering the left atrium (LA). There is a large atrial septal defect (double-headed arrow). ASept = atrial septum, RA = right atrium. Surgery involved completion of a Fontan procedure.

View larger version (154K): [in this window] [in a new window] [Download PPT slide]   Figure 5a.  Double aortic arch in a 2-week-old girl with stridor in whom ventilation was difficult with a respirator. (a) Contrast-enhanced CT scan shows symmetric bilateral carotid arteries (CC) and subclavian arteries (SA). (b) CT scan shows a larger right aortic arch and a smaller left aortic arch. (c) CT scan obtained 6 mm caudad to b shows that the right descending aorta gives rise to a left-sided patent ductus arteriosus (PDA), which courses posterior to the trachea and esophagus. The trachea is narrowed to 3 mm in transverse diameter. Surgery involved division of the double aortic arch with ligation of the patent ductus arteriosus.

View larger version (158K): [in this window] [in a new window] [Download PPT slide]   Figure 5b.  Double aortic arch in a 2-week-old girl with stridor in whom ventilation was difficult with a respirator. (a) Contrast-enhanced CT scan shows symmetric bilateral carotid arteries (CC) and subclavian arteries (SA). (b) CT scan shows a larger right aortic arch and a smaller left aortic arch. (c) CT scan obtained 6 mm caudad to b shows that the right descending aorta gives rise to a left-sided patent ductus arteriosus (PDA), which courses posterior to the trachea and esophagus. The trachea is narrowed to 3 mm in transverse diameter. Surgery involved division of the double aortic arch with ligation of the patent ductus arteriosus.

View larger version (148K): [in this window] [in a new window] [Download PPT slide]   Figure 5c.  Double aortic arch in a 2-week-old girl with stridor in whom ventilation was difficult with a respirator. (a) Contrast-enhanced CT scan shows symmetric bilateral carotid arteries (CC) and subclavian arteries (SA). (b) CT scan shows a larger right aortic arch and a smaller left aortic arch. (c) CT scan obtained 6 mm caudad to b shows that the right descending aorta gives rise to a left-sided patent ductus arteriosus (PDA), which courses posterior to the trachea and esophagus. The trachea is narrowed to 3 mm in transverse diameter. Surgery involved division of the double aortic arch with ligation of the patent ductus arteriosus.

View larger version (167K): [in this window] [in a new window] [Download PPT slide]   Figure 6a.  Right aortic arch with a right-sided patent ductus arteriosus in a 5-week-old girl with difficulty breathing. CT was performed to check for a vascular ring. Because the anatomy was complex, MR imaging was performed to further demonstrate the anomalies. (a, b) Contrast-enhanced CT scan (a) and axial MR image (b) obtained at similar levels show a right aortic arch (Ao). SVC = superior vena cava. (c) Oblique sagittal MR image shows a large patent ductus arteriosus (PDA) arising from the descending aorta (Ao) and extending to the right pulmonary artery (RPA). (d) Coronal MR image shows the right-to-left course of the patent ductus arteriosus (PDA) from the right-sided descending aorta (Ao) to the right pulmonary artery (RPA). LA = left atrium. (e, f) CT scan (e) and axial MR image (f) show the patent ductus arteriosus (PDA) extending from the descending aorta (Ao) to the right pulmonary artery (RPA), which is enlarged. The MR image (f) shows extrinsic compression of the airway at the level of the carina, which explains the clinical finding. Surgery involved ligation of the patent ductus arteriosus.

View larger version (154K): [in this window] [in a new window] [Download PPT slide]   Figure 6b.  Right aortic arch with a right-sided patent ductus arteriosus in a 5-week-old girl with difficulty breathing. CT was performed to check for a vascular ring. Because the anatomy was complex, MR imaging was performed to further demonstrate the anomalies. (a, b) Contrast-enhanced CT scan (a) and axial MR image (b) obtained at similar levels show a right aortic arch (Ao). SVC = superior vena cava. (c) Oblique sagittal MR image shows a large patent ductus arteriosus (PDA) arising from the descending aorta (Ao) and extending to the right pulmonary artery (RPA). (d) Coronal MR image shows the right-to-left course of the patent ductus arteriosus (PDA) from the right-sided descending aorta (Ao) to the right pulmonary artery (RPA). LA = left atrium. (e, f) CT scan (e) and axial MR image (f) show the patent ductus arteriosus (PDA) extending from the descending aorta (Ao) to the right pulmonary artery (RPA), which is enlarged. The MR image (f) shows extrinsic compression of the airway at the level of the carina, which explains the clinical finding. Surgery involved ligation of the patent ductus arteriosus.

View larger version (189K): [in this window] [in a new window] [Download PPT slide]   Figure 6c.  Right aortic arch with a right-sided patent ductus arteriosus in a 5-week-old girl with difficulty breathing. CT was performed to check for a vascular ring. Because the anatomy was complex, MR imaging was performed to further demonstrate the anomalies. (a, b) Contrast-enhanced CT scan (a) and axial MR image (b) obtained at similar levels show a right aortic arch (Ao). SVC = superior vena cava. (c) Oblique sagittal MR image shows a large patent ductus arteriosus (PDA) arising from the descending aorta (Ao) and extending to the right pulmonary artery (RPA). (d) Coronal MR image shows the right-to-left course of the patent ductus arteriosus (PDA) from the right-sided descending aorta (Ao) to the right pulmonary artery (RPA). LA = left atrium. (e, f) CT scan (e) and axial MR image (f) show the patent ductus arteriosus (PDA) extending from the descending aorta (Ao) to the right pulmonary artery (RPA), which is enlarged. The MR image (f) shows extrinsic compression of the airway at the level of the carina, which explains the clinical finding. Surgery involved ligation of the patent ductus arteriosus.

View larger version (193K): [in this window] [in a new window] [Download PPT slide]   Figure 6d.  Right aortic arch with a right-sided patent ductus arteriosus in a 5-week-old girl with difficulty breathing. CT was performed to check for a vascular ring. Because the anatomy was complex, MR imaging was performed to further demonstrate the anomalies. (a, b) Contrast-enhanced CT scan (a) and axial MR image (b) obtained at similar levels show a right aortic arch (Ao). SVC = superior vena cava. (c) Oblique sagittal MR image shows a large patent ductus arteriosus (PDA) arising from the descending aorta (Ao) and extending to the right pulmonary artery (RPA). (d) Coronal MR image shows the right-to-left course of the patent ductus arteriosus (PDA) from the right-sided descending aorta (Ao) to the right pulmonary artery (RPA). LA = left atrium. (e, f) CT scan (e) and axial MR image (f) show the patent ductus arteriosus (PDA) extending from the descending aorta (Ao) to the right pulmonary artery (RPA), which is enlarged. The MR image (f) shows extrinsic compression of the airway at the level of the carina, which explains the clinical finding. Surgery involved ligation of the patent ductus arteriosus.

View larger version (197K): [in this window] [in a new window] [Download PPT slide]   Figure 6e.  Right aortic arch with a right-sided patent ductus arteriosus in a 5-week-old girl with difficulty breathing. CT was performed to check for a vascular ring. Because the anatomy was complex, MR imaging was performed to further demonstrate the anomalies. (a, b) Contrast-enhanced CT scan (a) and axial MR image (b) obtained at similar levels show a right aortic arch (Ao). SVC = superior vena cava. (c) Oblique sagittal MR image shows a large patent ductus arteriosus (PDA) arising from the descending aorta (Ao) and extending to the right pulmonary artery (RPA). (d) Coronal MR image shows the right-to-left course of the patent ductus arteriosus (PDA) from the right-sided descending aorta (Ao) to the right pulmonary artery (RPA). LA = left atrium. (e, f) CT scan (e) and axial MR image (f) show the patent ductus arteriosus (PDA) extending from the descending aorta (Ao) to the right pulmonary artery (RPA), which is enlarged. The MR image (f) shows extrinsic compression of the airway at the level of the carina, which explains the clinical finding. Surgery involved ligation of the patent ductus arteriosus.

View larger version (181K): [in this window] [in a new window] [Download PPT slide]   Figure 6f.  Right aortic arch with a right-sided patent ductus arteriosus in a 5-week-old girl with difficulty breathing. CT was performed to check for a vascular ring. Because the anatomy was complex, MR imaging was performed to further demonstrate the anomalies. (a, b) Contrast-enhanced CT scan (a) and axial MR image (b) obtained at similar levels show a right aortic arch (Ao). SVC = superior vena cava. (c) Oblique sagittal MR image shows a large patent ductus arteriosus (PDA) arising from the descending aorta (Ao) and extending to the right pulmonary artery (RPA). (d) Coronal MR image shows the right-to-left course of the patent ductus arteriosus (PDA) from the right-sided descending aorta (Ao) to the right pulmonary artery (RPA). LA = left atrium. (e, f) CT scan (e) and axial MR image (f) show the patent ductus arteriosus (PDA) extending from the descending aorta (Ao) to the right pulmonary artery (RPA), which is enlarged. The MR image (f) shows extrinsic compression of the airway at the level of the carina, which explains the clinical finding. Surgery involved ligation of the patent ductus arteriosus.

View larger version (196K): [in this window] [in a new window] [Download PPT slide]   Figure 7.  Aortic coarctation in a 20-month-old boy. The aortic coarctation was suspected at clinical examination but was not clearly demonstrated at echocardiography. Oblique sagittal MR image shows focal narrowing (arrowhead) of the mid-descending thoracic aorta (Ao) with associated turbulent flow. This finding was ultimately diagnosed as Takayasu arteritis. Surgery involved resection of the stenotic segment with end-to-end anastomosis of the mid-descending thoracic aorta.

View larger version (123K): [in this window] [in a new window] [Download PPT slide]   Figure 8a.  Aortic hypoplasia and coarctation along with long-segment hypoplasia of the right and left pulmonary arteries in a 6-year-old girl with Williams syndrome. Ao = aorta. (a) Axial MR image shows a thick-walled ascending aorta, which is typical of Williams syndrome. The descending aorta (arrow) is minute, and the aortic arch was not identified on axial images. MPA = main pulmonary artery. (b) Oblique sagittal MR image shows hypoplasia of the aorta above the sinus of Valsalva with long-segment coarctation (Coarct) in the proximal descending aorta. Note the hypoplastic right pulmonary artery (RPA), which is seen in cross section posterior to the ascending aorta. Surgery involved repair of the coarctation.

View larger version (180K): [in this window] [in a new window] [Download PPT slide]   Figure 8b.  Aortic hypoplasia and coarctation along with long-segment hypoplasia of the right and left pulmonary arteries in a 6-year-old girl with Williams syndrome. Ao = aorta. (a) Axial MR image shows a thick-walled ascending aorta, which is typical of Williams syndrome. The descending aorta (arrow) is minute, and the aortic arch was not identified on axial images. MPA = main pulmonary artery. (b) Oblique sagittal MR image shows hypoplasia of the aorta above the sinus of Valsalva with long-segment coarctation (Coarct) in the proximal descending aorta. Note the hypoplastic right pulmonary artery (RPA), which is seen in cross section posterior to the ascending aorta. Surgery involved repair of the coarctation.

View larger version (196K): [in this window] [in a new window] [Download PPT slide]   Figure 9a.  Residual aortic coarctation in a 7-year-old boy who underwent balloon dilation of an aortic isthmic coarctation several years earlier. (a) Oblique sagittal MR image shows hypoplasia of the mid-aortic arch between the left common carotid artery (CC) and left subclavian artery (SA). Note that the left vertebral artery arises separately from the aortic arch proximal to the left subclavian artery. Ao = aorta. (b) Oblique sagittal MR image obtained after balloon dilation shows the remodeled aortic isthmus (arrow). No surgical repair is planned at present.

View larger version (188K): [in this window] [in a new window] [Download PPT slide]   Figure 9b.  Residual aortic coarctation in a 7-year-old boy who underwent balloon dilation of an aortic isthmic coarctation several years earlier. (a) Oblique sagittal MR image shows hypoplasia of the mid-aortic arch between the left common carotid artery (CC) and left subclavian artery (SA). Note that the left vertebral artery arises separately from the aortic arch proximal to the left subclavian artery. Ao = aorta. (b) Oblique sagittal MR image obtained after balloon dilation shows the remodeled aortic isthmus (arrow). No surgical repair is planned at present.

	Discussion

Top Abstract LEARNING OBJECTIVES Introduction Materials and Methods Results and Diagnostic... Discussion Conclusions References

In patients with tetralogy of Fallot with complex pulmonary artery anatomy, MR imaging and CT are useful in defining the pulmonary artery anatomy, along with the significant aortopulmonary collateral vessels (7,8). In children with tetralogy of Fallot, pulmonary atresia, and multiple aortopulmonary collateral vessels, single-stage primary repair is currently the best palliative approach for this challenging patient population (9,10). Specifically, MR imaging or CT defines the relationship of the branch aortopulmonary collateral arteries to the tracheobronchial tree, permitting the surgeon to minimize peritracheal dissection, which may be associated with postoperative bronchospasm. In addition, identification and enlargement of all branch pulmonary arterial stenoses is mandatory to fully access the pulmonary vascular bed so as to yield subsystemic right ventricular pressures after ventricular septation. Creation of neopulmonary arteries by unifocalization of the aortopulmonary collateral vessels can be achieved and cardiac bypass time can be minimized if the anatomy is accurately mapped preoperatively. MR imaging and CT are also useful in postoperative follow-up (2).

In the heterotaxy syndromes, patients often have unusual atriovenous connections. MR imaging is accurate in identification of the hepatic, systemic, and pulmonary veins and their relationships to both atria (11–13). Angiography and echocardiography are limited in their ability to demonstrate peculiar pulmonary and systemic venoatrial connections. Preoperative knowledge of these connections helps avoid intraoperative confusion and prolonged cardiac bypass times.

CT and MR are the imaging modalities of choice in patients suspected to have a vascular ring. They not only accurately demonstrate the vascular anomalies but also allow evaluation of possible airway compromise or esophageal impingement and provide inferential evidence concerning the presence and location of ligamentous structures. This information often eliminates the more traditional multistage work-up, which includes barium study, bronchoscopy, echocardiography, and angiography (14–16).

Treatment of aortic coarctation with balloon angioplasty or surgery is usually performed on the basis of typical clinical and echocardiographic findings without reliance on further imaging with MR or CT. In patients with atypical clinical or echocardiographic findings, we have found that MR imaging or CT yields helpful information, which resulted in changing of the treatment plan for each of the four cases described in this article. MR imaging and CT are also extremely helpful in following up patients who have been treated for coarctation and may have a residual stenosis, aneurysm, or intimal flap (17,18).

	Conclusions

Top Abstract LEARNING OBJECTIVES Introduction Materials and Methods Results and Diagnostic... Discussion Conclusions References

 
Various imaging modalities contribute diagnostic information in patients with congenital heart disease. MR imaging and CT are especially useful in demonstrating extracardiac anatomy, in which application they have become the procedures of choice for aortic arch lesions. MR imaging and CT also provide enhanced diagnostic accuracy in evaluation of the central and peripheral pulmonary arteries and aortopulmonary collateral vessels in patients with tetralogy of Fallot and in delineation of the peculiar venous anatomy and venoatrial connections in patients with heterotaxy. Echocardiography continues to be the preferred modality for imaging intracardiac anatomy and hemodynamics. The MR imaging and CT examinations are most productive when specific diagnostic questions are posed by a collaborative team composed of cardiologists, surgeons, and radiologists after careful review of the clinical and other imaging data. This tailored approach maximizes the diagnostic yield and minimizes redundancy so that the length of study and sedation times can be abbreviated. Recent improvements in imaging equipment allow very short imaging times and sophisticated reconstruction with both CT and MR imaging. A thorough preoperative understanding of complex cardiovascular anatomy in patients with congenital heart disease facilitates a directed and prepared surgical approach.

	Acknowledgments

 
The authors thank Eleanor Murphy for her expert assistance in manuscript preparation.

	Footnotes

 
See the commentary by Greenberg following this article.

	References

Top Abstract LEARNING OBJECTIVES Introduction Materials and Methods Results and Diagnostic... Discussion Conclusions References

 

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