Comparison Study of Subtraction CT Angiography and Conventional CT Angiography in the Clipped Intercranial Aneurysms

Objective To evaluate the value of the subtraction CT angiography and Conventional CT angiography in following up the patients with clipped aneurysms. Materials and Methods 34 consecutive patients with clipped aneurysms underwent 64 spiral CT and DS angiography. CT raw data were reconstructed with volume rendering (VR) and maximum intensity projection (MIP) to display the vessels. Two observers assessed the sites of the clips and patency of the vessels by reviewing both CT and DSA independently. Results Subtraction CT angiography demonstrated 6 patients with neck remnant lesions(6/34) and 2 cases with stenosis in the parent vessels(2/34), which all were confirmed by DSA. In one patient(1/34),a neck remnant lesion was seen on DS angiograms but missed on Subtraction CT angiograms. The sensitivity, specificity and accuracy for detecting neck remnants on Subtraction CT angiography were 85.7%,100% and 96.1% respectively. The sensitivity, specificity and accuracy for evaluating vessels potency were all 100%. Conventional CT angiography detected 5 neck remnant lesions and missed 2 cases, misdiagnosed 1 case proximal obturation of the right middle artery. The sensitivity, specificity and accuracy for detecting neck remnants on conventional CT angiography were 71.4%,100% and 94.4% respectively; the sensitivity, specificity and accuracy for evaluating vessels potency were 100%, 96.8% and 97.1% respectively. Conclusion Subtraction CT angiography is an accurate noninvasive tool and can be used as the main method in following up the patients with clipped aneurysms.