Multiplanar reformatting and three-dimensional reconstruction: for pre-operative assessment of the thoracic aorta by computed tomography

Introduction: Conventional CT demonstrates pathology of the thoracic aorta. This study aimed to evaluate the additional contributions to surgical planning of multiplanar reformatting, maximum intensity projections and three-dimensional (3-D) reconstruction. Design: Retrospective. Subject and Methodology: Fifty-three patients with newly diagnosed pathology of the thoracic aorta were scanned over a 15-month period; 25 scans were spiral acquisitions. Scans were acquired during and following rapid injection of 100 ml of intravenous iopromide. The reconstructed data was displayed as axial images, oblique or other multiplanar reformats and shaded surface display 3-D reconstructions. Two radiologists and two surgeons reviewed the images. The axial images were assessed initially, subsequently the reformats and 3-D reconstructed views were examined looking particularly for additional information that might add to the surgical management. Results: Pathologies encountered were aortic dissection (21 patients including two with Marfan's syndrome), saccular aneurysms (eight), fusiform aneurysms (16), aortic root and ascending aortic dilatation (seven) and coarctation (one). The relationship of aneurysms and dissections to major vessels are better shown with 3-D reconstruction or oblique reformats. Morphology of saccular aneurysms, particularly the neck, is well shown with 3-D reconstruction. Coarctation was best demonstrated by oblique reformats. There was little additional information from 3-D reconstruction or reformats in assessment of type A dissection. Improved spatial orientation by visualization in varying projections was helpful for surgical planning in certain cases of type B dissection, fusiform aneurysms and aortic root and ascending aortic root dilatation. Spiral acquisitions have the advantage of speed and hence a greater anatomical coverage for a single breath-hold. Conclusion: Oblique reformats and 3-D reconstruction, although using identical data as the axial images, in specific cases were felt to aid surgical assessment of aneurysms and dissections, thus assisting pre-operative planning.