Efficacy of targeted CT angiography in evaluation of intracranial internal carotid artery disease

Rationale and Objectives. This study evaluated the efficacy of targeted computed tomographic (CT) angiography in the diagnosis of intracranial internal carotid artery (ICA) disease and compared the results of routine and targeted CT angiography. Materials and Methods. Fifty-four patients (24 male and 30 female patients aged 2 months to 87 years) were examined with CT angiography. Digital subtraction angiography (DSA) was performed in 42. CT angiograms were reconstructed with the maximum-intensity projection (MIP) algorithm. Targeted CT angiography was performed by individually reconstructing a single ICA territory. Each ICA was divided into four segments, and findings of routine MIP CT angiography, routine MIP plus targeted CT angiography, and DSA were reviewed independently by two neuroradiologists for vascular lesions involving each segment. Routine and targeted CT angiograms were also evaluated to determine how well both ICAs were visualized. Results. Routine CT angiography was rated good or excellent for ICA visualization in 64% of cases, compared with 81% for targeted CT angiography (P =.0005). The overall agreement between routine CT angiography and DSA and between routine plus targeted CT angiography and DSA was 92% and 94%, respectively. There was no statistically significant difference between the percentages of vascular lesions detected with routine CT angiography alone and with routine plus targeted CT angiography. Both methods tended to show false-positive findings of steno-occlusive disease, but targeted CT angiography showed details of aneurysms and stenotic lesions that were easily overlooked with routine CT angiography alone. Conclusion. Routine plus targeted CT angiography, while providing superior image quality, did not have much clinical effect; further assessment may be needed.