Direct sagittal computed tomography in Graves' ophthalmopathy.

Standard axial transverse orbital computed tomography scans show the medial and lateral rectus muscles very well but section the superior and inferior rectus muscles obliquely. Determining enlargement of the superior and inferior recti in Graves' disease can therefore be difficult on axial transverse scans. We have obtained sagittal, coronal, and axial transverse orbital scans in a series of patients with Graves' ophthalmopathy and have compared the images in each plane. Direct sagittal and coronal scans were obtained without image regeneration from axial transverse sections by using a wide-aperture Varian body scanner and a special accessory table. Sagittal and coronal scans can demonstrate enlargement of the superior or inferior muscles even in cases in which the medial and lateral recti are normal. Since scans performed at approximately 20 degrees to the sagittal plane are parallel to the long axis of the orbit, they demonstrate orbital anatomy better than scans in the true sagittal plane.