A flow-diverting stent is not a pressure-diverting stent.

The approach for treatment of large and fusiform intracranial aneurysms has evolved from stent-assisted coiling to treatment with flow-diverting stents. The treatment results for these stents are promising; however, early postprocedural aneurysm rupture has been described. The exact cause of rupture is unknown but might be related to intra-aneurysmal flow and pressure changes. We measured intra-aneurysmal pressure before, during, and after placement of a flow-diverting stent by using a dual-sensor guidewire. The pressure inside the aneurysm momentarily decreased during placement but was restored to baseline values within minutes. The flow-diverting stent does not seem to protect the aneurysm from the stress induced by pressure or pressure changes within the lumen.

Comparison of phase-contrast MR imaging and endovascular sonography for intracranial blood flow velocity measurements.

BACKGROUND AND PURPOSE: Local hemodynamic information may help to stratify rupture risk of cerebral aneurysms. Patient-specific modeling of cerebral hemodynamics requires accurate data on BFV in perianeurysmal arteries as boundary conditions for CFD. The aim was to compare the BFV measured with PC-MR imaging with that obtained by using intra-arterial Doppler sonography and to determine interpatient variation in intracranial BFV. MATERIALS AND METHODS: In 10 patients with unruptured intracranial aneurysms, BFV was measured in the cavernous ICA with PC-MR imaging in conscious patients before treatment, and measured by using an intra-arterial Doppler sonography wire when the patient was anesthetized with either propofol (6 patients) or sevoflurane (4 patients). RESULTS: Both techniques identified a pulsatile blood flow pattern in cerebral arteries. PSV differed >50 cm/s between patients. A mean velocity of 41.3 cm/s (95% CI, 39.3-43.3) was measured with PC-MR imaging. With intra-arterial Doppler sonography, a mean velocity of 29.3 cm/s (95% CI, 25.8-32.8) was measured with the patient under propofol-based intravenous anesthesia. In patients under sevoflurane-based inhaled anesthesia, a mean velocity of 44.9 cm/s (95% CI, 40.6-49.3) was measured. CONCLUSIONS: We showed large differences in BFV between patients, emphasizing the importance of using patient-specific hemodynamic boundary conditions in CFD. PC-MR imaging measurements of BFV in conscious patients were comparable with those obtained with the intra-arterial Doppler sonography when the patient was anesthetized with a sevoflurane-based inhaled anesthetic.

Cerebral perfusion long term after therapeutic occlusion of the internal carotid artery in patients who tolerated angiographic balloon test occlusion.

BACKGROUND AND PURPOSE: Therapeutic carotid occlusion is an established technique for treatment of large and giant aneurysms of the ICA, in patients with synchronous venous filling on angiography during BTO. Concern remains that hemodynamic alterations after permanent occlusion will predispose the patient to new ischemic injury in the ipsilateral hemisphere. The purpose of this study was to assess whether BTO with synchronous venous filling is associated with normal CBF long term after carotid sacrifice. MATERIALS AND METHODS: Eleven patients were included (all women; mean age, 50.5 years; mean follow-up, 38.5 months). ASL with single and multiple TIs was used to assess CBF and its temporal characteristics. Selective ASL was used to assess actual territorial contribution of the ICA and BA. Collateral flow via the AcomA or PcomA or both was determined by time-resolved 3D PCMR. Paired t tests were used to compare CBF and timing parameters between hemispheres. RESULTS: Absolute CBF values were within the normal range. There was no significant CBF difference between hemispheres ipsilateral and contralateral to carotid sacrifice (49.4 ± 11.2 versus 50.1 ± 10.1 mL/100 g/min). Arterial arrival time and trailing edge time were significantly prolonged on the occlusion side (816 ± 119 ms versus 741 ± 103 ms, P = .001; and 1765 ± 179 ms versus 1646 ± 190 ms, P < .001). Two patients had collateral flow through the AcomA only and were found to have increased timing parameters compared with 9 patients with mixed collateral flow through both the AcomA and PcomA. CONCLUSIONS: In this small study, patients with synchronous venous filling during BTO had normal CBF long term after therapeutic ICA occlusion.

Partially thrombosed intracranial aneurysms presenting with mass effect: long-term clinical and imaging follow-up after endovascular treatment.

BACKGROUND AND PURPOSE: Partially thrombosed aneurysms as a distinct entity form a diverse collection of complex aneurysms characterized by organized intraluminal thrombus and solid mass. Endovascular treatment options are PVO or selective coil occlusion of the remaining lumen. We present long-term clinical and angiographic results of endovascular treatment of unruptured partially thrombosed aneurysms that presented with symptoms of mass effect. MATERIALS AND METHODS: Between 1994 and 2008, 30 partially thrombosed aneurysms were treated by selective coiling and 26 by PVO. Of 56 aneurysms, 53 (95%) were large or giant. Neurologic recovery during a mean clinical follow-up of 42.7 months was established. Evolution of aneurysm size during a mean follow-up of 26.6 months in 46 patients was assessed with MR imaging. RESULTS: Seventeen of 56 patients (30%) fully recovered, 22 patients (39%) partially recovered, 11 patients (20%) were unchanged, and 6 patients (11%) died. Complete recovery more often occurred after PVO than after coiling (12 of 26 versus 5 of 30, P = .02). Aneurysm size reduction occurred more often after PVO (17 of 18 versus 2 of 28, P < .001). Five aneurysms continued to grow after coiling, resulting in death in 3. During follow-up, 27 additional treatments were performed in 19 patients, all treated with coiling. CONCLUSIONS: In partially thrombosed aneurysms presenting with mass effect, the results of PVO are much better than those of selective coiling. After coiling, additional treatments are often needed, and some aneurysms keep growing. When PVO is not tolerated or not possible, surgical options should be considered before proceeding with coiling.

Late adverse events in coiled ruptured aneurysms with incomplete occlusion at 6-month angiographic follow-up.

BACKGROUND AND PURPOSE: Patients with coiled ruptured aneurysms with incomplete occlusion at 6 months are not only at risk for rebleed during further follow-up but also for complications of angiographic follow-up and retreatment, and for progressive mass effect by uncontrollable aneurysm growth. We assessed the frequency and outcome of all these possible aneurysm-related events in 124 patients with incompletely occluded aneurysms at 6 months during a follow-up of 419 patient-years. MATERIALS AND METHODS: Between 1994 and 2007, 901 ruptured aneurysms were coiled and 713 (79%) had 6-month angiographic follow-up, of which 124 were incompletely occluded (17%). These 124 patients were followed for a mean of 41 months (median, 30 months; range, 1-150 months). RESULTS: During follow-up, 307 angiograms were obtained without complications. Of 124 aneurysms, 88 were retreated (71%). Fifteen aneurysms were retreated more than once. Altogether, 124 additional treatments were performed, and no complications occurred (0%; 95% CI, 0.0-3.6%). Four aneurysms rebled, causing death in 2 patients. Another 4 patients experienced progressive mass effect by growth of the coiled aneurysm, leading to death in 1. The annual event rate was 1.9%, the annual mortality was 0.7%, and the annual rebleed rate was 1.0% (8, 3, and 4 in 419 patient-years). CONCLUSIONS: In this study of patients with coiled ruptured aneurysms with incomplete occlusion at 6 months, a strategy of imaging follow-up and retreatment when possible leads to a low incidence of serious adverse events. Rebleeding and progressive mass effect of the aneurysm were responsible for these events, not complications from additional treatment or angiographic follow-up.

Intracranial blood-flow velocity and pressure measurements using an intra-arterial dual-sensor guidewire.

Hemodynamics is thought to play a role in the growth and rupture of intracranial aneurysms. In 4 patients, we obtained local pressure and BFV by using a dual-sensor pressure and Doppler velocity wire within and in vessels surrounding unruptured aneurysms. Local BFVs can serve as boundary conditions for computational fluid dynamics, whereas pressure recordings provide direct information on the mechanical load imposed on the aneurysm. Both measurements may thus add to patient-specific rupture-risk assessment.

Evaluation of the occlusion status of coiled intracranial aneurysms with MR angiography at 3T: is contrast enhancement necessary?

BACKGROUND AND PURPOSE: MR angiography (MRA) is increasingly used as a noninvasive imaging technique for the follow-up of coiled intracranial aneurysms. However, the need for contrast enhancement has not yet been elucidated. We compared 3D time-of-flight MRA (TOF-MRA) and contrast-enhanced MRA (CE-MRA) at 3T with catheter angiography. MATERIALS AND METHODS: Sixty-seven patients with 72 aneurysms underwent TOF-MRA, CE-MRA, and catheter-angiography 6 months after coiling. Occlusion status on MRA was classified as adequate (complete and neck remnant) or incomplete by 2 independent observers. For TOF-MRA and CE-MRA, interobserver agreement, intermodality agreement, and correlation with angiography were assessed by kappa statistics. RESULTS: Catheter-angiography revealed incomplete occlusion in 12 (17%) of the 69 aneurysms; 3 aneurysms were excluded due to MR imaging artifacts. Interobserver agreement was good for CE-MRA (kappa = 0.77; 95% confidence interval [CI], 0.55-0.98) and very good for TOF-MRA (kappa = 0.89; 95% CI, 0.75-1.00). Correlation of TOF-MRA and CE-MRA with angiography was good. The sensitivity of TOF-MRA and CE-MRA was 75% (95% CI, 43%-95%); the specificity of TOF-MRA was 98% (95% CI, 91%-100%) and of CE-MRA, 97% (95% CI, 88%-100%). All 5 incompletely occluded aneurysms, which were additionally treated, were correctly identified with both MRA techniques. Areas under the receiver operating characteristic curve for TOF-MRA and CE-MRA were 0.90 (95% CI, 0.79-1.00) and 0.91 (95% CI, 0.79-1.00). Intermodality agreement between TOF-MRA and CE-MRA was very good (kappa = 0.83; 95% CI, 0.65-1.00), with full agreement in 66 (96%) of the 69 aneurysms. CONCLUSIONS: In this study, TOF-MRA and CE-MRA at 3T were equivalent in evaluating the occlusion status of intracranial aneurysms after coiling. Because TOF-MRA does not involve contrast administration, this method is preferred over CE-MRA.