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Small-Vessel Stents for Intracranial Angioplasty: In Vitro Comparison of Different Stent Designs and Sizes by Using CT Angiography

2003; American Society of Neuroradiology; Volume: 24; Issue: 8 Linguagem: Inglês

1936-959X

Stefan Hähnel, Manuel Trossbach, C. Braun, Sabine Heiland, Michael Knauth, K. Sartor, Marius Hartmann,

Intracranial Aneurysms: Treatment and Complications

BACKGROUND AND PURPOSE: Our purpose was to evaluate whether CT angiography is a suitable alternative to conventional angiography in the evaluation of small-vessel stents for intracranial angioplasty. METHODS: CT angiographic appearances of 23 stents of different designs and sizes (2.0, 3.0, and 4.0 mm) were investigated after they were filled with a solution of 0.9% NaCl or diluted contrast medium. For each stent, artificial lumen narrowing (ALN) was measured, and the difference in the number of pixels with a Hounsfield value below 200 HU between the two filling states, DIFFHU<200, was calculated to provide an objective indicator of the size of the evaluable stent diameter. RESULTS: With a window width of 1500 HU at a window level of 400 HU, ALN ranged from 66.8% to 97.7% in the group of 2.0-mm stents and from 38.6% to 66.8% in the groups of 3.0- and 4.0-mm stents. For the 2.0-mm stents, DIFFHU<200 was zero. In the groups of 3.0- and 4.0-mm stents, DIFFHU<200 ranged from 0.3 to 6.7, corresponding to a diameter of 0.13–3.0 mm, when the pixel size was presupposed to be 0.449 mm. CONCLUSION: CT angiographic evaluation of small-vessel patency after stent placement is considerably impaired by ALN. Stent manufacturers should be aware of potential artifacts caused by their stents during noninvasive diagnostic studies such as CT angiography. One major problem of angioplasty with stent placement is the occurrence of in-stent neointimal growth, which can result in hemodynamically relevant restenosis or occlusion of the stented vessel segment (instent restenosis). The method of choice for the detection of restenosis within stented cerebral vessel segments is intra-arterial conventional angiography. This method is associated with an incidence of neurologic complications of about 0.5% (1, 2) and an incidence of clinically silent brain lesions of about 20% (3). To our knowledge, no systematic report has been published to describe artificial lumen narrowing (ALN) in small-vessel stents, as measured with CT angiography. The aim of our study was to determine whether CT angiography is suitable as a noninvasive alternative to conventional angiography in the evaluation of small-vessel stents used for intracranial angioplasty. Of particular interest was the measurement of ALN caused by the stent material within the stented vessel segment to determine whether CT angiography can be used to detect restenosis within the stent.