Direct comparison of computed tomography and magnetic resonance imaging for characterization of posterior left atrial morphology.

OBJECTIVE: Accumulating evidence points to the central importance of the posterior left atrium (PLA) for atrial fibrillation (AF). Catheter ablation intended to cure AF is increasingly practiced; performance and assessment of this procedure is enhanced by accurate imaging of PLA anatomy. Prior reports have suggested that both computed tomographic (CT) and magnetic resonance (MR) imaging techniques provide accurate PLA images. These techniques have never been compared directly. MATERIALS AND METHODS: Twenty patients referred for catheter ablation underwent preoperative imaging using both CT and MR. Each technique was used to create a multidimensional image of the PLA. RESULTS: Within patients, morphologic and dimensional PLA indices, including number of individual pulmonary venoatrial junctions, presence of ostial branches, circumference of each venoatrial junction, venoatrial junction "non-circularity", and distance between ipsilateral superior and inferior venoatrial junctions, were well correlated. CONCLUSIONS: CT and MR-based images of the PLA appear comparable. Technique selection should involve considerations of toxicity, tolerance, and local resources.

Intracranial volume changes in craniosynostotic rabbits: effects of age and surgical correction.

BACKGROUND: The premature fusion of one or more cranial sutures, termed craniosynostosis, alters normal brain growth patterns and results in compensatory changes in the cranial vault. The authors previously reported that bilateral coronal suture fusion resulted in a reduction in intracranial volume in a rabbit model of nonsyndromic, familial coronal suture synostosis. METHODS: The current follow-up study involved collecting cross-sectional three-dimensional computed tomographic head scans from 142 rabbits (70 normal, 44 with uncorrected synostosis, and 28 synostosed rabbits with coronal suturectomy) at 0, 10, 25, 42, 84, and 126 days of age. Intracranial contents were reconstructed, and indirect intracranial volume was calculated. RESULTS: Results revealed a significant (p < 0.05) postsynostotic reduction of intracranial volume (23 percent) by 25 days of age in rabbits with uncorrected craniosynostosis compared with normal controls, which continued through 84 days of age. Also, rabbits with surgically released synostosis, using a simple strip suturectomy, showed significantly (p < 0.05) greater intracranial volume at 25 days of age compared with unoperated synostosed rabbits. However, no changes in intracranial volume were noted between 42 and 84 days of age in rabbits with surgically released synostosis, at which point their intracranial volume was 30 percent less than that in normal control rabbits. CONCLUSIONS: These data suggest that in rabbits with uncorrected craniosynostosis, compensatory changes in the neurocranium were not capable of compensating for the loss of sutures as growth sites. The results also showed that that surgical release of the synostosed suture improved intracranial volume in the short term (25 to 42 days) but failed to change it in the long term (42 to 84 days), possibly because of rapid resynostosis of the suturectomy site. This study suggests that surgical release of the suture fusion site alone may not be adequate to allow for normal intracranial volume growth in synostotic rabbits. For this reason, it may be efficacious to design and develop adjunct protein and gene therapies to prevent resynostosis and improve postoperative intracranial volume in craniosynostotic individuals.

Multi-detector row CT of the left atrium and pulmonary veins before radio-frequency catheter ablation for atrial fibrillation.

Radio-frequency catheter ablation (RFCA) of the distal pulmonary veins and posterior left atrium is increasingly being used to treat recurrent or refractory atrial fibrillation that resists pharmacologic therapy or cardioversion. Successful RFCA of atrial fibrillation requires resolution of abnormal rhythms while minimizing complications and can be achieved with precise, preprocedural, three-dimensional (3D) anatomic delineation of the target, the atriopulmonary venous junction. Three-dimensional multi-detector row computed tomography (CT) of the pulmonary veins and left atrium provides the necessary anatomic information for successful RFCA, including (a) the number, location, and angulation of pulmonary veins and their ostial branches unobscured by adjacent cardiac and vascular anatomy, and (b) left atrial volume. The 3D multi-detector row CT scanning and postprocessing techniques used for pre-RFCA planning are straightforward. Radiologists must not only understand these techniques but must also be familiar with atrial fibrillation and the technical considerations and complications associated with RFCA of this condition. In addition, radiologists must be familiar with anatomic variants of the left atrium and distal pulmonary veins and understand the importance of these variants to the referring cardiac interventional electrophysiologist.

Characterization of left atrium and distal pulmonary vein morphology using multidimensional computed tomography.

OBJECTIVES: This study was designed to examine the dimensions and morphology of left atrial (LA) and distal pulmonary veins (PVs) using multidetector helical computed tomography (MDCT). BACKGROUND: Detailed knowledge of LA and PV anatomy will assist in the development of techniques for ablative intervention. Multidetector helical computed tomography is a method for multidimensional imaging of cardiac anatomy. METHODS: Multidetector helical computed tomography was used to image the LA and PVs in 70 subjects with and 47 subjects without atrial fibrillation (AF). Accuracy of the MDCT data was confirmed by correlation with echocardiography and endocardial electrogram recordings. RESULTS: Left atrial and PV dimensions were significantly larger in AF versus non-AF subjects, men versus women, and subjects with persistent versus paroxysmal AF. There were no differences between groups in morphologic detail. CONCLUSIONS: Multidetector helical computed tomography images of the LA and PVs are accurate and provide detailed anatomic information. Significant differences in dimensions but not morphologic detail were apparent between groups.