The Use of Three-Dimensional (3-D) Computed Tomography (CT) in Preoperative Planning for Hemivertebra Excision

PURPOSE: This study compares the operative findings at the time of hemivertebra excision with the preoperative anatomy shown by 3-D CT scans and plain films.

METHODS: We reviewed the records and imaging studies of patients who underwent isolated one stage simultaneous anterior and posterior hemivertebra excision during the time period between Jan.1, 1997 and Dec.31, 2001. The preoperative radiographs, preoperative 3-D CT scans, and operative reports were each reviewed in a blinded fashion. We then compared the imaging results with the operative findings in order to assess the reliabilty of these preoperative studies.

RESULTS: Fifteen patients were identified with a median age at surgery of 2.2 years and the median preoperative scoliosis of 38 degrees. The hemivertebra location was as follows: 3 thoracic, 4 thoracolumbar, 6 lumbar, 2 lumbosacral. The findings at operation correlated with the anterior and posterior anatomy on 3-D CT scans in all patients (100% sensitivity). The plain film analysis revealed the anterior anatomy correctly in fourteen of fifteen patients. Posterior bifid segments at operation were present in five patients; all of these were seen on the 3-D CT scans and none were seen on plain films. Eight of the fifteen patients had fused posterior lamina identified at operation;one of these was identified on plain films (13% sensitivity) while all were seen on 3-D CT scans (100% sensitivity).

CONCLUSIONS: This study shows that the anterior and posterior anatomy of a hemivertebra and adjacent segments can reliably be determined by 3-D CT scanning prior to surgical excision.