When an inversion of the ratio between the resistance index of the ophthalmic artery and that of the common carotid or an index value lower than 0.70 in the ophthalmic artery is observed, further investigation is needed as this situation cannot be considered normal. The value of the index in the ophthalmic arteries, when the circulation is normal in the extra- and intracranial arteries is rarely lower than 0.70. The resistance index of the ophthalmic arteries was, in all cases, greater than that of the ipsilateral common carotid artery which in turn, was greater than that of the internal carotid. The mean values (standard deviation) of the measured parameters for the ophthalmic arteries were: insonation depth: 38.38 mm (2.60 mm), peak systolic velocity: 34.71 cm/sec (6.38 cm/sec), end diastolic velocity: 7.95 cm/sec (1.70 cm/sec), resistive index: 0.77 (0.04). Peak systolic velocity, end diastolic velocity and resistance index (RI) of the common carotid, internal carotid and ophthalmic arteries, as well as the insonation depth of the ophthalmic arteries were measured. A colour Doppler ultrasound examination of the neck arteries was performed, followed by a colour Doppler ultrasound examination of the 120 ophthalmic arteries included. Sixty healthy subjects (age range 20-74 years) with normal vascular findings, stratified by age and sex were recruited to the study. The proposed new velocity criteria accurately define residual stenosis >or =20%, in-stent restenosis >or =50%, and high-grade in-stent restenosis > or =80% in the stented carotid artery.The aim of this study was to assess the flow characteristics in ophthalmic arteries and to detect their possible relationships to those in the common and internal carotid arteries. These changes persist during long-term follow-up and across all grades of in-stent restenosis after CAS. Ultrasound velocity criteria developed for native arteries overestimate the degree of in-stent restenosis encountered. Progressively increasing PSV and ICA/CCA ratios correlate with evolving restenosis within the stented carotid artery. Receiver operating characteristic analysis demonstrated the following optimal threshold criteria: residual stenosis > or =20% (PSV >or =150 cm/s and ICA/CCA ratio > or =2.15), in-stent restenosis > or =50% (PSV > or =220 cm/s and ICA/CCA ratio > or =2.7), and in-stent restenosis > or =80% (PSV 340 cm/s and ICA/CCA ratio > or =4.15). 85) and ICA/CCA ratios (r(2) = 0.76) correlated most with the degree of stenosis. The accuracy of CTA vs carotid angiograms was confirmed (r(2) = 0.88) in a subset of 19 patients. Available for analysis were 189 pairs of ultrasound and procedural carotid angiogram measurements 99 pairs of ultrasound and CTA measurements during routine follow-up and 29 pairs of ultrasound and carotid angiograms measurements during follow-up for suspected high-grade in-stent restenosis > or =80% (n = 310 pairs of observations, ultrasound vs carotid angiograms/CTA). During a mean follow-up of 4.6 years (range, 1 to 10 years), 23 patients died and 64 were lost. Of 255 CAS procedures that were reviewed, 39 had contralateral ICA stenosis and were excluded from the study. The DUS protocol included peak-systolic (PSV) and end-diastolic velocity (EDV) measurements in the native common carotid artery (CCA), proximal stent, mid stent, distal stent, and distal internal carotid artery (ICA). DUS findings were therefore available for comparison with luminal stenosis measured by carotid angiograms or CTA in all these patients. Patients with suspected high-grade in-stent restenosis on DUS imaging underwent diagnostic carotid angiograms. Patients were followed up with annual DUS imaging and underwent both ultrasound scans and computed tomography angiography (CTA) at their most recent follow-up visit. In the present study, we test whether ultrasound velocity measurements correlate with increasing degrees of in-stent restenosis in patients undergoing CAS and develop customized velocity criteria to identify residual stenosis > or =20%, in-stent restenosis > or =50%, and high-grade in-stent restenosis > or =80%.Ĭarotid angiograms performed at the completion of CAS were compared with duplex ultrasound (DUS) imaging performed immediately after the procedure. Ultrasound velocity criteria for the diagnosis of in-stent restenosis in patients undergoing carotid artery stenting (CAS) are not well established.
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