The Added Value of Volume-of-Interest C-Arm CT Imaging during Endovascular Treatment of Intracranial Aneurysms.

BACKGROUND AND PURPOSE: Successful endovascular treatment of intracranial aneurysms requires understanding the exact relationship of implanted devices to the aneurysm, parent artery, and other branch vessels during the treatment. Intraprocedural C-arm CT imaging has been shown to provide such information. However, its repeated use is limited due to increasing radiation exposure to the patient. The goal of this study was to evaluate a new volume-of-interest C-arm CT imaging technique, which would provide device-specific information through multiple 3D acquisitions of only the region of interest, thus reducing cumulative radiation exposure to the patient. MATERIALS AND METHODS: VOI C-arm CT images were obtained in 28 patients undergoing endovascular treatment of intracranial aneurysms. VOI images were acquired with the x-ray source collimated around the deployed device, both horizontally and vertically. The images were reconstructed by using a novel prototype robust reconstruction algorithm to minimize truncation artifacts from double collimation. The reconstruction accuracy of VOI C-arm CT images was assessed quantitatively by comparing them with the full-head noncollimated images. RESULTS: Quantitative analysis showed that the quality of VOI C-arm CT images is comparable with that of the standard Feldkamp, Davis, and Kress reconstruction of noncollimated C-arm CT images (correlation coefficient = 0.96 and structural similarity index = 0.92). Furthermore, 91.5% reduction in dose-area product was achieved with VOI imaging compared with the full-head acquisition. CONCLUSIONS: VOI imaging allows multiple 3D C-arm CT acquisitions and provides information related to device expansion, parent wall apposition, and neck coverage during the procedure, with very low additional radiation exposure to the patient.

Endovascular Recanalization in Acute Ischemic Stroke Using the Solitaire FR Revascularization Device with Adjunctive C-Arm CT Imaging.

In this clinical report, we examined a single-center experience by using the Solitaire FR Revascularization Device in the treatment of acute ischemic stroke in which there was poor initial visualization of the occluded arterial branches by using biplanar cerebral angiography. In all cases, adjunctive C-arm CT was used during the deployment of the thrombectomy device to gain additional information regarding device placement and expansion. Outcome measures included the extent of reperfusion, posttreatment changes in NIHSS scores, posttreatment TICI scores, cerebral hemorrhage, and survival. Clot removal with successful arterial recanalization was achieved in 15/18 cases (83.3%) with TICI scores of 2b/3 in all patients who had initial recanalization. The NIHSS score improved, on average, from 19 pretreatment to 11 posttreatment, and 72% of patients survived. In cases of acute stroke in which there is little information available regarding the positioning and deployment of a retrievable stent during mechanical thrombectomy, the use of C-arm CT may provide more information about device placement across an area of thrombus.

Effect of structural remodeling (retraction and recoil) of the pipeline embolization device on aneurysm occlusion rate.

BACKGROUND AND PURPOSE: During endovascular treatment of unruptured aneurysms with the Pipeline Embolization Device, an oversized device is often selected to achieve better wall apposition; however, this device oversizing could be related to overelongation and possible delayed enlargement of the stented region. The purpose of this study is to investigate the relationship between oversize and treatment outcome. MATERIALS AND METHODS: The DynaCT images of 14 aneurysms treated by a single Pipeline Embolization Device were retrospectively analyzed. 3D images of the deployed device were compared with those acquired at the 6-month follow-up for qualitative and quantitative evaluation. The diameter and length of the Pipeline Embolization Device were measured at both time points and compared for determination of the device changes. RESULTS: Structural changes of the device have been observed, and it was found that the Pipeline Embolization Device influences the vessel curvature in some cases. On average, it increases its diameter by 0.23 mm and decreases its length by 2.88 mm within 6 months of initial deployment. Excessive elongation beyond its nominal length is correlated with a lower aneurysm occlusion rate at the 6-month follow-up. CONCLUSIONS: Not only does a Pipeline Embolization Device reconstruct the aneurysm and parent artery, but its entire structure goes through a gradual remodeling process. The relative deformation between the device and the artery indicates suboptimal wall apposition. Device oversizing does not have a direct effect on shortening or recoil. The aneurysm occlusion rate, however, is lowered by overelongation of the Pipeline Embolization Device.

Analysis of intra-aneurysmal flow for cerebral aneurysms with cerebral angiography.

BACKGROUND AND PURPOSE: Hemodynamics is an important factor in the development and rupture of cerebral aneurysms. Current techniques for measuring blood flow in cerebral aneurysms suffer from various limitations and have not been able to address our clinical needs. A new technique has been developed for effective evaluation of intra-aneurysmal flow based on high-frame-rate cerebral angiography, especially for flow-diverters. MATERIALS AND METHODS: Six patients with 7 unruptured ICA aneurysms were imaged with a specially designed DSA protocol (a 3D DSA and a 2D DSA acquired at 30 frames/s, with a 2-mL/s contrast injection rate). Images of these cases were analyzed to determine the intra-aneurysmal flow based on the newly developed technique. Patient-specific aneurysm models were used for CFD calculation, and intra-aneurysmal flow rates were computed numerically. The intra-aneurysmal flow rates from the 2 methods were then compared. RESULTS: There is a linear relationship between intra-aneurysmal flow ratios obtained from high-frame-rate cerebral angiography and CFD calculation (R = 0.99). A high frame rate (30 frames/s) provides a better estimate of intra-aneurysmal flow than low frame rates (7.5 frames/s and 15 frames/s). CONCLUSIONS: The CFD calculation validates the estimate of intra-aneurysmal hemodynamics from cerebral angiography. The linear relationship obtained by using these 2 techniques can be used for real-time assessment of intra-aneurysmal hemodynamics for cerebral aneurysms.

Aneurysm ostium angle: a predictor of the need for stent as assistance for endovascular aneurysm coiling in internal carotid artery sidewall aneurysms.

BACKGROUND AND PURPOSE: There is no satisfactory parameter that can predict the need for assistant devices for endovascular aneurysm coiling. Our aim was to evaluate the utility of MOA as a predictor of the need for stent-assisted coiling in ICA sidewall aneurysms. MATERIALS AND METHODS: From a retrospective review of an internal data base, 55 consecutive ICA sidewall aneurysms were identified. Thirty-two of the aneurysms were treated by using endovascular techniques. Because 23 of the 55 aneurysms were either untreated or clipped, 3 experienced interventionalists reviewed the 3D images of these aneurysms and then made a decision as to whether stent-assisted coiling would have been required. Thirty-one of the 55 aneurysms would have required stent-assisted coiling, while 24 would not. Neck width, DNR, AR, and MOA were obtained from each aneurysm by using prototype software. These parameters were then correlated with the requirement of stent-assisted coiling. RESULTS: MOA and neck width of aneurysms requiring stent-assisted coiling were significantly larger than those not requiring stent-assisted coiling (P < .001 and <0.001, respectively). Although the DNR and AR of aneurysms requiring stent-assisted coiling were smaller than those not requiring it, the difference was not significant (P = .22 and 0.12, respectively). ROC analysis revealed that MOA was the parameter that best correlated with the need for stent-assisted coiling. Inclusion of MOA with the rest of the parameters significantly increased the predictive performance regarding the need for stent-assisted coiling (P = .005). CONCLUSIONS: In this small study, MOA was a useful parameter to predict the need for stent-assisted coiling in ICA sidewall aneurysms. Further prospective study of this parameter for aneurysms at multiple locations is required to determine its ultimate value.

Embolization of Cerebral Aneurysms with Spherically Shaped Detachable Microcoils (MicruSphere Microcoil System). A Single Centre Experience.

SUMMARY: We present our initial experience of concentric-filling technique using MicruSphere 3D coils (Micrus Endovascular, San Jose, CA) in the treatment of intracranial aneurysms. 149 intracranial saccular aneurysms in 142 consecutive patients (mean age 56.6-/+12.7, ruptured in 54 (36.2%)) were treated with the concentric-filling technique. The mean aneurysm volume was 169.0-/+363.0 mm(3). Neck remodeling technique was used in 120 (80.5%). Procedure-related problems were recorded. Initial embolization results were evaluated, and the coil packing density was calculated. Clinical and angiographic follow-ups were performed after six months. Any changes in embolization status were classified as 'improved', 'unchanged', or 'worse'. The overall packing density was 40.1% (range 10.5-90.9%). The permanent morbidity and mortality rates were 4.0% and 1.3%, respectively. The initial Raymond and Roy classification results were class 1 in 37 aneurysms (24.8%), class 2 in 50 (33.6%), and class 3 in 62 (41.6%). On the mean follow-up examination of 8.2 months in 103 patients (72.5%), there were one transient ischemic attack, one minor stroke, and one instance of rebleeding. Angiographic follow-up in 101 aneurysms (67.8%) showed the change in embolization status as 'improved' in 42 aneurysms (41.6%), 'unchanged' in 42 (41.6%), and 'worse' in 17 (recanalisation rate, 16.8%). The concentric-filling technique using Micrusphere 3D coils was effective in achieving high packing density which in turn resulted in stable embolization in the majority of the aneurysms. Longer follow-up is warranted to determine the durability of these results.

Wall shear stress on ruptured and unruptured intracranial aneurysms at the internal carotid artery.

BACKGROUND AND PURPOSE: Hemodynamics is often recognized as one of the major factors in aneurysm rupture. Flow impingement, greater pressure, and abnormal wall shear stress are all indications for aneurysm rupture. Characterizing wall shear stress for intracranial aneurysms at similar anatomic locations may help in understanding its role. MATERIALS AND METHODS: Twenty-six intracranial aneurysms at the paraclinoid and superclinoid segments of the internal carotid artery from 25 patients between July 2006 and July 2007 were studied retrospectively. Among them, 8 aneurysms were ruptured and 18 were unruptured. Computational fluid dynamics was used to determine the wall shear distribution. Morphologic and hemodynamic variables was analyzed by using the Mann-Whitney rank sum test. RESULTS: Wall shear stress was qualitatively the same throughout the cardiac cycle; thus, only wall shear stress at the end of diastole was compared. Both ruptured and unruptured aneurysms have similar maximal wall shear stress (26 versus 23 N/m(2)), and mean wall shear stress is shown to be a function of the aneurysm area. Ruptured aneurysms also have a greater portion of aneurysm under low wall shear stress (27% versus 11% for unruptured aneurysms, P = .03). CONCLUSION: For intracranial aneurysms at the internal carotid artery, an area of low wall shear is associated with aneurysm rupture.

Dual antiplatelet therapy monitoring for neurointerventional procedures using a point-of-care platelet function test: a single-center experience.

BACKGROUND AND PURPOSE: Growing evidence of the relationship between poor antiplatelet response and occurrence of clinical events elicited the need of monitoring the response which has not been part of our daily practice. We present our initial experience with a new point-of-care antiplatelet-function test (VerifyNow assay) in neurointerventional procedures. MATERIALS AND METHODS: Among the 106 consecutive patients from July 2006 to April 2007, ninety-eight met the inclusion criteria. Our preferred antiplatelet regimen was aspirin (325 mg daily) and clopidogrel (300 mg of loading dose followed by 75 mg daily) starting 5-10 days before the procedure. The test results were reported as aspirin-reaction unit (ARU) for aspirin and P2Y(12) reaction units (PRU), baseline (BASE), and percentage inhibition for the P2Y(12) assay and were summarized as mean +/- SD of the values. We analyzed the effects of several factors of poor clopidogrel response (<40% inhibition). The occurrence of thrombotic events was recorded. RESULTS: The mean ARU of aspirin assays was 438.3 +/- 47.9 (range, 350-632), and the response was poor in 2 patients (2.1%). For clopidogrel, the mean of the BASE, PRU, and percentage inhibition was 356.8 +/- 56.3 (range, 234-495), 198.9 +/- 104.4 (range, 8-401), and 45.2 +/- 27.1% (range, 0-98), respectively. Forty-two patients (42.9%) showed poor response. Multivariate analysis showed greater body weight (81.9 Kg +/- 19.1 kg versus 69.9 +/- 15 kg) in the poor-response group. All 3 cases of intraprocedural thrombosis (3.1%) were observed only in the poor-response group. CONCLUSION: We observed a high frequency of poor clopidogrel responses in the neurointerventional setting. Routine monitoring of the drug response would be helpful for the early identification of poor antiplatelet responders so that we may modify the regimen and/or treatment plan.

3D rotational digital subtraction angiography may underestimate intracranial aneurysms: findings from two basilar aneurysms.

3D digital subtraction angiography (DSA) allows clinicians to review intracranial aneurysms and other vascular lesions. We report 2 basilar aneurysms that were imaged by both 3D DSA and DynaCT. These 2 techniques produced very different aneurysm appearances. Anterior portions of the aneurysms were invisible on 3D DSA but were revealed by DynaCT. These aneurysms appeared to have been flattened by image artifacts in 3D DSA. Pulsation and gravity are 2 possible causes of aneurysm underestimation.

Intimal Thickening after Placement of a Neuroform Stent. Its Incidence and Relation to Angiographic Follow-up Results of Aneurysm Embolization.

SUMMARY: Little attention has been given to the intimal thickening of the parent artery associated with the use of Neuroform stent. The purposes of this study were are to analyze quantifyanalyze the incidence of the parent artery intimal thickening the incidence and pattern of luminal changes, to to see somedetermine possible predictors of the phenomenonof the intimal thickening, to to evaluate the its effectthe phenomenonrestenosis on the aneurysm treatment results. We reviewed the initial and six-month followup angiographic images in 32 intracranial aneurysm patients treated with Neuroform stent and coilsin wide-necked aneurysm treatment. The initial embolization results were evaluated by the Raymond and Roy classification. The angiographic changes from immediate post-embolization to the six-month follow-up were classified as 'improved', 'unchanged' and 'worse'. The occurrencerates of parent artery intimal thickening was observed. Any perceivable change in the stented segment of the parent artery was considered as 'intimal thickening' and any change of >/=50% as 'significant thickening'. Fisher exact tests and logistic regression analysis were applied to determine the relation between the occurrence of the intimal thickening and several variables. The incidence of the intimal thickening was 18.8% (6/32) and of significant thickening, 3.1% (1/32). The change in angiographic occlusion of the aneurysm was 'improved' in 40.6% (13/32), 'unchanged' in 37.5% (12/32), and 'worse' in 21.9% (7/32). Among the variables, patient's age (>/=55) and follow-up angiographic results ('improved') correlated with the occurrence of the intimal thickening. Of notable finding was all six cases with intimal thickening of the parent artery were associated with 'improved' in their followup angiographic result. Neuroform-associated intimal thickening usually occurs in younger patients and is frequently associated with improved angiographic result of the aneurysm embolization on follow-up.

Neonate with vein of Galen malformation and heart failure: serial changes in plasma B-type natriuretic peptide following endovascular embolization.

We report a neonate with vein of Galen malformation (VGM) who developed congestive heart failure (CHF) early after birth. Serial changes in plasma B-type natriuretic peptide (BNP) following an endovascular embolization procedure for VGM were mirrored in his clinical CHF status. The plasma BNP level markedly increased to 1800 pg/ml (normal, <100 pg/ml) in accordance with the severity of CHF. It rapidly decreased to 356 pg/ml during the first week after endovascular embolization for VGM. In the following 3 weeks there was an unexpected upward trend in plasma BNP despite echocardiography revealing normal biventricular function. After additional evaluation and treatment for CHF, BNP decreased again and the patient's clinical status concurrently improved. The patient was discharged with a normal BNP level. Monitoring serial plasma BNP provides valuable information regarding the need for additional evaluation or treatment of newborns with CHF and may be used to document improvement.

Aneurysms of the posterior cerebral artery: classification and endovascular treatment.

BACKGROUND AND PURPOSE: We present a retrospective review of our experience in the endovascular treatment of posterior cerebral artery (PCA) aneurysms. We detail the anatomic location of these aneurysms, the technique of endovascular treatment, morphologic results, and clinical outcome. We also discuss the segmental anatomy of the PCA as it relates to the various neurologic deficits that may result from occlusion of the parent artery. METHODS: From 1993 to 1998, 20 patients (12 female, eight male; mean age, 44 yrs) harboring a PCA aneurysm were treated via an endovascular approach. One patient had two aneurysms, comprising a total of 21 lesions. Fourteen (66%) of 21 aneurysms were saccular in nature, five (24%) were giant serpentine aneurysms, and two (10%) were posttraumatic. All aneurysms were treated using Guglielmi detachable coils (GDC) either by selective obliteration of the aneurysm sac or by parent artery occlusion. RESULTS: Fourteen (66%) of the 21 aneurysms were successfully treated with preservation of the parent artery. In the remaining seven (33%), the parent artery was permanently occluded. The overall complication rate in this series was 15%, with a permanent morbidity rate of 10% and a 0% mortality rate. CONCLUSION: Aneurysms of the PCA are rare compared with other locations in the intracranial circulation. Saccular PCA aneurysms can be treated effectively, by use of GDC, to obliterate the aneurysm yet preserve the parent artery. Fusiform and giant serpentine aneurysms of the PCA can effectively be treated by permanent occlusion of the parent artery; in these cases, thorough knowledge of the PCA segmental anatomy is crucial in order to select the site of occlusion and to avoid major neurologic deficits.

Incidence of cerebral vasospasm after endovascular treatment of acutely ruptured aneurysms: report on 69 cases.

Cerebral vasospasm is the most common cause of morbidity and mortality in patients admitted to the hospital after suffering aneurysmal subarachnoid hemorrhage (SAH). The early surgical removal of subarachnoid clots and irrigation of the basal cisterns have been reported to reduce the incidence of vasospasm. In contrast to surgery, the endovascular treatment of aneurysms does not allow removal of subarachnoid clots. In this study the authors measured the incidence of symptomatic vasospasm after early endovascular treatment of acutely ruptured aneurysms with Guglielmi detachable coils (GDCs). Sixty-nine patients classified as Hunt and Hess Grades I to III underwent occlusion of intracranial aneurysms via GDCs within 72 hours of rupture. The amount of blood on the initial computerized tomography (CT) scan was classified by means of Fisher's scale. Symptomatic vasospasm was defined as the onset of neurological deterioration verified with angiographic or transcranial Doppler studies. Hypertensive, hypervolemic, hemodilution therapy, with or without intracranial angioplasty, was used to treat vasospasm after GDC placement. Symptomatic vasospasm occurred in 16 (23%) of 69 patients. The clinical grade at admission and the amount of blood on the initial CT were both associated with the incidence of subsequent vasospasm. At 6-month clinical follow-up examination, 12 of these 16 patients experienced a good recovery, two were moderately disabled, and two patients had died of vasospasm. In conclusion, the 23% incidence of symptomatic vasospasm in this series compares favorably with that found in conventional surgical series of patients with acute aneurysmal SAH. These results indicate that endovascular therapy does not have an unfavorable impact on cerebral vasospasm.

Treatment of dissecting pseudoaneurysm of the cervical internal carotid artery using a wall stent and detachable coils: case report.

OBJECTIVE AND IMPORTANCE: This case illustrates the use of an endovascular stent and coiling combination to treat a giant wide-necked pseudoaneurysm of the cervical internal carotid artery. CLINICAL PRESENTATION: A 20-year-old male patient presented with a bilateral dissection of the cervical internal carotid artery and a right giant wide-necked pseudoaneurysm of the cervical segment of the internal carotid artery after a high-speed motor vehicle collision. INTERVENTION: After failing conservative therapy, the patient was treated by endovascular placement of a Palmaz wall stent at the level of the pseudoaneurysm and filling of the pseudoaneurysm with multiple Guglielmi detachable coils. Obliteration of the pseudoaneurysm was achieved, and patency of the right internal carotid artery was maintained. CONCLUSION: The patient's neurological symptoms resolved completely after treatment, and he sustained no neurological complications during the 20-month follow-up period. This case illustrates the successful treatment of a wide-based giant pseudoaneurysm by using a combination of an endovascular stent and coil embolization.

Fatal subarachnoid hemorrhage from the rupture of a totally intracavernous carotid artery aneurysm: case report.

Intracavernous carotid artery aneurysms usually cause symptoms because of gradual expansion without rupture. Most such aneurysms that do rupture lead to a carotid-cavernous fistula. Very few cases of rupture leading to subarachnoid hemorrhage have been reported. We report a case in which rupture of an entirely intracavernous carotid artery aneurysm led to death from a massive subarachnoid hemorrhage.

Giant serpentine aneurysms: radiographic features and endovascular treatment.

PURPOSE: To describe the characteristic CT, MR, and angiographic features of giant serpentine aneurysms and discuss their endovascular treatment. METHODS: Thirteen patients with giant serpentine aneurysms were studied at our institution in the last 3 years. They all underwent CT and MR studies as well as cerebral angiography. More recently, some of the patients were studied with MR angiography. Seven patients had endovascular occlusion of the giant serpentine aneurysms, 3 with N-butyl cyanoacrylate, 2 with Guglielmi detachable coils, and 2 with detachable balloons. RESULTS: Giant serpentine aneurysms mimic cerebral neoplasms on CT and MR studies; they are often associated with mass effect and adjacent edema, and they enhance with contrast medium. The cerebral angiogram shows a residual irregular lumen of the partially clotted aneurysm, which continues into normal branches supplying the distal arterial territory. Six patients were treated successfully with an endovascular approach consisting of complete and permanent occlusion of the parent artery. CONCLUSION: Giant serpentine aneurysms from a subgroup of large intracranial aneurysms that have specific CT, MR, and angiographic features, which should be recognized before their treatment. The endovascular treatment of the aneurysm consists of permanent occlusion of the parent artery.

Long-term histopathologic changes in canine aneurysms embolized with Guglielmi detachable coils.

PURPOSE: To evaluate the long-term histologic changes, including those in the ultrastructure of the neoendothelium, occurring in experimental canine aneurysms obliterated with Guglielmi detachable coils. METHODS: Ten experimental aneurysms were surgically created in mongrel dogs using side-to-side jugular carotid fistulas that were subsequently ligated to form blind pouch venous aneurysms dependent on the carotid circulation. The aneurysms were obliterated with Guglielmi detachable coils, and the animals were kept in observation. Six months after the endovascular obliteration of the aneurysms, repeat carotid arteriography was performed to assess for potential recanalization of the aneurysms. The animals were then killed and submitted for autopsy. The carotid artery and the embolized aneurysm were resected and studied with light and electron microscopy. RESULTS: Both completely obliterated and recanalized aneurysms were excluded from the parent circulation by an endothelialized layer of connective tissue. The fundus of the aneurysm was completely obliterated by heavy reactive fibrous tissue surrounding the coils with very minimal, if any, inflammatory reaction. The neointima is composed of three well-identifiable layers, the most superficial of which is formed of new endothelial cells positioned next to each other in a cobblestone fashion over a basal membrane. CONCLUSION: In the absence of histologic data in human aneurysms obliterated with Guglielmi detachable coils, several observations made in our experimental study help in the understanding of the long-term results expected from this endovascular technique.

Metastatic adenocarcinoma to the brain: MR with pathologic correlation.

PURPOSE: To describe the appearance on T2-weighted scans of metastatic adenocarcinoma to the brain and to show that the hypointensity frequently associated with these lesions is not related to the presence of mucin, blood products, iron, or calcium. METHODS: The MR scans of 14 patients with metastatic adenocarcinoma to the brain were reviewed retrospectively. The signal intensity on T2-weighted scans of the solid enhancing portion of the tumors was compared with white matter. Histologic examination of the surgical specimens included special stains to search for calcium, mucin, and iron. RESULTS: Eight of nine surgical and all six nonsurgical lesions were either iso- or hypointense to white matter on T2-weighted scans. There was no correlation with tumor histology or the presence of mucin, blood products, iron, or calcium. CONCLUSIONS: The presence of a hypointense intraaxial mass on T2-weighted scans strongly suggests the possibility of metastatic adenocarcinoma. The MR appearance is not explained by the presence of mucin, blood products, iron, or calcium. This phenomenon most likely reflects the relaxation parameters of the tissue from which the metastasis arose.

MR appearance of an orbital leiomyoma.

The authors describe the MR appearance of an intraconal orbital vascular leiomyoma that probably arose from smooth muscle in the wall of a vein. Cavernous hemangiomas, schwannomas, neurofibromas, and other well-encapsulated masses can have a similar appearance.