Preliminary Observation Of Optical Coherence Tomography Following Neck Vascular Stenting

OBJECTIVES:1. This study was conducted to investigate the safety and feasibility of frequency domain optical coherence tomography (FD-OCT) examination within the neck vascular. The surrounding tissue after stent implantation in the neck vascular of was analyzed by FD-OCT preliminarily.2. FD-OCT imaging technology was used for the analysis of neointimal proliferation after carotid artery stent placement.3. The study further evaluated the clinical value of FD-OCT for vascular disorders in the neck vascular measurement related parameters to guide interventional therapy.METHODS:Both Digital subtraction angiography(DSA) and FD-OCT were carried out again on the nine patients who had undergone endovascular stenting in the criminal blood vessels for three months because of their neck vascular diseases.13 stents were inserted into the 12 vascular lesion points in 9 patients, including 4 stents in common carotid artery (CCA),5 stents in internal carotid artery(ICA),3 stents in vertebral artery(VA) and 1 stents in left subclavian artery(SUBA). FD-OCT imaging was used to observe whether there are abnormal conditions, including the fracture and malaposition of the stents, plaque and thrombosis in stents, tissue prolapse, vascular dissection because of intimal tear, restenosis due to intimal hyperplasia,ect. Of 9 pieces of carotid stent success for OCT images were analyzed, and the intervals of 1 mm to support section 1 frame to observe, to obtain 271 clear image, stick a wall of evaluating image support, the further divided into two groups, group A (n=147), serving as the experimental group achieving good apposition of the stent to the wall (distance between the stent and the vessel wall,< 200μm); group B (n=124), regarding as the control group with incomplete stent apposition (distance between the stent and the vessel wall,≥ 200μm). Three to six months after stent implantation; cerebral angiography was performed on the seven patients, and FD-OCT imaging of the vascular lesions was further conducted, for the comparison of intravascular neointimal proliferation between groups. DSA and FD-OCT examination were both performed in nine patients, and the comparison of the two techniques was made regarding the differences of vascular disorders in head and neck and vascular measurement related parameters between groups.RESULTS:1.OCT was successfully carried out on 8 patients with one failing case. We observed that the strut of one in twelve stents failed to completely seal the aneurysm on the arterial wall through OCT imaging. Malaposition was exited in the strut of partial stentsand plaques and thrombus were also formed in 2 stents. Different levels of vascular intimal hyperplasia were obsevered in 6 stents in all 11 lesions in the blood vessels and one restenosis patients resulting from tunica intima hyperplasia suffered another endovascular stenting. It was by the OCT imaging that different degrees of tissue prolapsed was also detected in 3 stents with total 4 tissue prolapsed. 2.OCT images were successfully acquired. The maximal neointima, luminal loss in diameter and cross sectional a, and restenosis in diameter and CSA were significantly statistically different within three groups. The maximal intimal proliferations post stenting in group A were significantly lower than group B(0.27 mm±0.15 mm vs. 0.79 mm±0.46 mm, P= 0.014), luminal loss of diameter in group A were significantly lower than group B(0.26 mm±0.16 mm vs.1.23 mm±0.85 mm, P= 0.009), restenosis rates in diameter in group A were significantly less than group B (9%±5% vs.35%±23%, P=0.008).There were neointimal coverage over the stent struts mostly considering all 9 carotid artery stents, severe incomplete stent apposition was found over the remaining stent struts, associated with prolapse in the peripheral tissues and thrombus formation.3.As for carotid aneurysm, DSA and OCT measurement results showed no significant difference in aneurysm neck length, but DSA could indicate a relatively more clearly aneurysm morphology and provided with more aneurysm data; for patients with vascular stenosis of the neck, there was no significant statistical significance with respect to DSA and OCT target reference vessel diameter (5.37 mm ±1.78 mm vs.5.58 mm±1.33 mm, P=0.782), and target vessel stenosis length (3.89 mm±0.85 mm vs.4.09 mm±0.64 mm, P=0.645); however, statistically significance were detected regarding the narrow lumen diameter (2.36 mm±1.02 mm vs.1.68 mm±0.72 mm, P= 0.039), and the narrow lumen stenosis rate (49%±25%vs.58%±32%, P=0.018). OCT imaging results also showed that 1 patient with stenosis of the lesion showed a ruptured plaque with thrombosis.CONCLUSIONS:1. The application of FD-OCT imaging technique is safe and feasible within the vasculars of the neck. FD-OCT can clearly display the surrounding tissue after stent implantation in the neck vascular; 2. FD-OCT imaging can clearly show neointimal proliferation over the stent surface and struts, neointimal proliferation can be covered over the entire surface of the stent within 6 months after stent implantation. The study also showed that incomplete stent apposition may contribute to an abnormal neointimal proliferation, even leading to restenosis in the lumen; 3. There are significantly differences in DSA and FD-OCT for detecting vascular disorders in head and neck and vascular measurement related parameters, both of which have their advantages and disadvantages, but FD-OCT has important significance for evaluating vascular disorders in the neck vascular after stent implantation treatment.