Fenestration of the middle cerebral artery detected by MR angiography.

Unlike fenestration of the posterior cerebral arterial circulation, fenestration of the anterior cerebral arterial circulation has not been well described. We investigated the location and configuration of fenestration of the middle cerebral artery (MCA) detected by magnetic resonance (MR) angiography. We found 6 fenestrations of the MCA among cranial MR angiography images obtained from about 2,000 patients during the past 9 years at our institution using either of two 1.5T imagers. All images were obtained by the three-dimensional time-of-flight technique. Maximum-intensity projection images in the horizontal rotation view were displayed stereoscopically. All 6 fenestrations had small slit-like configurations, five located at the proximal M1 segment, the other, at the middle M1 segment. No associated aneurysm was found. Although MCA fenestration is extremely rare and cerebral artery fenestration usually has no clinical significance, an aneurysm can arise at the proximal end of the fenestration. Thus, recognizing MCA fenestration is important when interpreting cranial MR angiograms.     

Three-dimensional time-of-flight MR angiography for evaluation of intracranial aneurysms after endosaccular packing with Guglielmi detachable coils: comparison with 3D digital subtraction angiography

The sensitivities and specificities of three-dimensional time-of-flight MR angiography (3D-TOF MRA) and 3D digital subtraction angiography (3D-DSA) were compared for evaluation of cerebral aneurysms after endosaccular packing with Guglielmi detachable coils (GDCs). Thirty-three patients with 33 aneurysms were included in this prospective study. 3D-TOF MRA and 3D-DSA were performed in the same week on all patients. Maximal intensity projection (MIP) and 3D reconstructed MRA images were compared with 3D-DSA images. The diameters of residual/recurrent aneurysms detected on 3D-DSA were calculated on a workstation. In 3 (9%) of 33 aneurysms, 3D-TOF MRA did not provide reliable information due to significant susceptibility artifacts on MRA. The sensitivity and specificity rates of MRA were 72.7 and 90.9%, respectively, for the diagnosis of residual/recurrent aneurysm. The diameters of residual/recurrent aneurysms that could not be detected by MRA were significantly smaller than those of detected aneurysms (mean 1.1 vs mean 2.3 mm). In one aneurysm of the anterior communicating artery (ACoA), the relationship between the residual aneurysm and the ACoA was more evident on MRA than DSA images. MRA can detect the recurrent/residual lumen of aneurysms treated with GDCs of up to at least 1.8 mm in diameter. 3D-TOF MRA is useful for follow-up of intracranial aneurysms treated with GDCs, and could partly replace DSA.     

Basilar artery fenestrations detected by MR angiography

Basilar artery (BA) fenestrations are the most frequently observed fenestrations of the cerebral arteries. Our goal was to examine the magnetic resonance (MR) angiographic incidence, location, and characteristic configuration of BA fenestration. Between April 1996 and March 2000, 600 cranial MR angiographies were performed at our institution. The majority of the patients examined had or were suspected to have cerebrovascular disease. We retrospectively reviewed these 600 MR angiograms. A 1.5 Tesla scanner was used in all studies, and maximum intensity projection (MIP) images obtained using the three-dimensional time-of-flight (3D-TOF) technique were displayed stereoscopically. Ten BA fenestrations (1.7%) were detected on MR angiograms. In 87 cases from the early period, the vertebrobasilar (VB) junction was unfortunately not included in the imaging slices. Eight of the 10 fenestrations were located at the proximal BA: six of them were small with a slit-like shape, and two were relatively large with a convex-lens-like shape. A small fenestration was located at the distal BA, and the remaining one was a total duplication of the BA. We stress that knowledge and recognition of BA fenestration are useful and important in the interpretation of cranial MR angiography. Since saccular aneurysms are reported to arise frequently at BA fenestration, the VB junction should be included in the imaging slices of routine cranial MR angiography.     

Fenestrations of the anterior communicating artery: incidence on 3D angiography and relationship to aneurysms

BACKGROUND AND PURPOSE: Demonstration of fenestrations of the anterior communicating artery (AcomA) with conventional digital subtraction angiography is very uncommon. The purpose of this study was to assess the incidence of visible fenestrations of the AcomA on 3D rotational angiography (3DRA) and to evaluate the relationship between fenestrations of the AcomA and aneurysms of the AcomA.MATERIALS AND METHODS: We systematically reviewed 305 datasets of 3DRA of the internal carotid artery in 305 patients with aneurysms of the anterior circulation on a dedicated workstation for the presence of fenestrations on the AcomA.RESULTS: In 78 of 305 3DRAs, only the ipsilateral A2 segment was visible; thus, the AcomA could not be evaluated. Of the remaining 227 3DRAs, a fenestration of the AcomA was present in 12 (5.3%; 95% CI, 3.0%–9.1%). Of 12 fenestrations of the AcomA, 10 (83%) were associated with 1 or more aneurysms of the AcomA. Of 305 patients, 133 had an aneurysm on the AcomA, and in 127 of these, the AcomA was visible. Of 127 AcomA aneurysms with a visible AcomA, 10 were associated with fenestration, which accounted for an incidence of AcomA fenestrations with AcomA aneurysms of 7.9% (95% CI, 4.2%–14.0%). The proportion of fenestrations of the AcomA with aneurysms of the AcomA was 4.4% (10/227), and the proportion of AcomA fenestration with an aneurysm at another location was 0.9% (2/227). This difference was statistically significant (P = .040). Even in retrospect, 11 of 12 fenestrations were not visible on 2D DSA images.CONCLUSION: In selected patients with aneurysms of the anterior circulation, fenestrations in the AcomA were found with 3DRA in 5.3% of datasets. Most fenestrations were associated with 1 or more aneurysms of the AcomA.

The anterior communicating artery (AcomA) is a small connecting artery between the paired anterior cerebral arteries and provides an important anastomotic channel for collateral circulation through the circle of Willis. In the embryologic stage, the AcomA develops from a multichanneled vascular network that coalesces to a variable degree by the time of birth.¹ A wide variety exists in the anatomy of the AcomA complex. A common variation is aplasia or hypoplasia of one A1 segment. In this variation, the other A1 continues as two A2 segments and an AcomA can hardly be defined.² In large autopsy and surgical series, single, double, or even triple fenestrations of the AcomA are reported in approximately 40% of specimens.^3–5 Despite this frequent occurrence in anatomic studies, angiographic demonstration of fenestrations of the AcomA is very uncommon. With recent advances in 3D rotational angiography (3DRA), high-resolution images are obtained that can be freely rotated. In this study, we systematically reviewed 305 datasets of 3DRA of the internal carotid artery in 305 patients with aneurysms of the anterior circulation to assess the incidence of visible AcomA fenestrations and to evaluate the relationship between AcomA fenestrations and AcomA aneurysms.     

Three-dimensional time-of-flight MR angiography in the evaluation of cerebral aneurysms

We review our preliminary experience with the use of three-dimensional (3D) time-of-flight (TOF) magnetic resonance (MR) angiography (MRA) in the assessment of intra- and extracranial aneurysms. Six patients were examined: Five had intracranial aneurysms and one had a cervical carotid pseudoaneurysm. A 3D rephased gradient recalled echo pulse sequence and maximum intensity projection (MIP) reconstruction algorithm were used. Magnetic resonance angiography, spin echo MR, and conventional angiography were retrospectively reviewed with specific regard to individual vessel visualization, aneurysm depiction, and presence of artifact related to acquisition techniques or MIP reconstruction. All aneurysms were detected on MRA, and anatomical correlation with conventional angiography was excellent. Significant problems included loss of visualization of small vessels, intraluminal signal loss in large vessels, subacute thrombus simulating flow on MIP reconstructions, and limited projections obtainable with MIP techniques. Adequate MRA assessment of aneurysms can be obtained using a combination of T1-weighted spin echo images and 3D TOF MRA. Review of all components of the MRA is required. MRA may be useful in screening asymptomatic patients for intracranial aneurysms as well as in the follow-up of patients treated with balloon occlusion.     

血管成像技术诊断内脏动脉瘤的临床价值

目的:探讨MSCT血管成像(MSCTA)及三维对比增强磁共振血管成像(3DDCEMRA)在腹腔内脏动脉瘤诊断和治疗中的价值。方法:回顾性分析分别经MSCTA及3DDCEMRA检查诊断的腹腔内脏动脉瘤38例患者的影像资料,采用容积重组(VR)、多平面重组(MPVR)、及最大密度投影(MIP)进行重组。结果:行MSCTA及3DMRA检查的38例患者中发现内脏动脉瘤42个,其中脾动脉瘤12个,肝动脉瘤6个,腹腔干动脉瘤8个,肠系膜上、下动脉瘤分别为6个和2个,肾动脉8个。VR、MIP、MPR可准确、清晰地显示瘤体位置、形态、范围、瘤壁、载瘤动脉和与周围血管的关系。结论:MSCTA和3DDCEMRA是简单、快速、无创、安全、可靠的血管成像技术,在诊断内脏动脉瘤方面,具有分辨力高,快速,准确,经济等优点,对腹腔内脏动脉瘤的检出具有较高的敏感度和特异度,提供的详尽信息可为尽快确定治疗方案提供依据,是诊断内脏动脉瘤的首选方法。     

64层螺旋CT脑血管造影在颅内动脉瘤诊断中的应用

目的:与DSA相对照,探讨64层螺旋CT脑血管造影在颅内动脉瘤中的诊断价值。方法:对29例临床怀疑颅内动脉瘤的患者行64层螺旋CT脑血管造影(CTA)和DSA检查,使用GE64层Lightspeed VCT获得原始图像,所有病例均采用多层面重建(multiplanar reconstruction,MPR)、容积再现(volume rendering,VR)、薄层块最大密度投影(thin-slab maximumintensity projectjon,TS MIP)。后处理图像及DSA图像由2位放射科医生共同评估。结果:29例患者中,DSA证实25例共27个动脉瘤,其中2例为2个动脉瘤。与DSA结果相对照,CTA共检出25例26个动脉瘤,漏诊了1个颈出动脉瘤。CTA清晰显示了动脉瘤的形态、大小及载瘤动脉,3例动脉瘤瘤颈DSA未显示,CTA显示了全部动脉瘤的瘤颈。结论:64层CTA在颅内动脉瘤的诊断中具有极高价值,特别在显示动脉瘤瘤颈方面具有独特的优势,对临床治疗具有指导意义。     

Influence of perianeurysmal environment on the deformation and bleb formation of the unruptured cerebral aneurysm: assessment with fusion imaging of 3D MR cisternography and 3D MR angiography

BACKGROUND AND PURPOSE: Surface irregularity and bleb formation are anatomical factors that are associated with aneurysm rupture. The perianeurysmal environment has been proposed as one factor that may influence aneurysm morphology. We have developed a fusion imaging technique of 3D MR cisternography and angiography that allows clear visualization of an aneurysm and its environment. This technique may prove useful in further understanding of the natural history of intracranial aneurysms. METHODS: Fusion images of 3D MR cisternography and angiography were reconstructed by a perspective volume-rendering algorithm from the volume datasets of MR cisternography, obtained by a T2-weighted 3D fast spin-echo sequence, and coordinated MR angiography, by a 3D time-of-flight sequence. On the fusion images, the anatomic relationship of an aneurysm to the perianeurysmal structures was assessed, and the influence of perianeurysmal environment on the deformation and bleb formation of the aneurysm was investigated. RESULTS: Marked and minor deformation and bleb formation of the aneurysmal dome were found at the areas confronted or adjacent to a certain contact with perianeurysmal structures, including cranial nerves, brain parenchyma, cranial base bones, petroclinoidal dural folds, and dura mater. CONCLUSION: Fusion images of 3D MR cisternography and angiography can depict the contact of an aneurysm with its perianeurysmal environment; this may provide an additional parameter in consideration for the natural history of cerebral aneurysms.     

Development of "de novo" aneurysms following endovascular procedures

Two personal cases of "de novo" aneurysms of the anterior communicating artery (ACoA) occurring 9 and 4 years, respectively, after endovascular carotid occlusion are described. A review of the 30 reported cases (including our own two) of "de novo" aneurysms after occlusion of the major cerebral vessels has shown some features, including a rather long time interval after the endovascular procedure of up to 20-25 years (average 9.6 years), a preferential ACoA (36.3%) and internal carotid artery-posterior communicating artery (ICA-PCoA) (33.3%) location of the "de novo" aneurysms, and a 10% rate of multiple aneurysms. These data are compared with those of the group of reported spontaneous "de novo" aneurysms after SAH or previous aneurysm clipping. We agree that the frequency of "de novo" aneurysms after major-vessel occlusion (two among ten procedures in our series, or 20%) is higher than commonly reported (0 to 11%). For this reason, we suggest that patients who have been submitted to endovascular major-vessel occlusion be followed up for up to 20-25 years after the procedure, using non-invasive imaging studies such as MR angiography and high-resolution CT angiography. On the other hand, periodic digital angiography has a questionable risk-benefit ratio; it may be used when a "de novo" aneurysm is detected or suspected on non-invasive studies. The progressive enlargement of the ACoA after carotid occlusion, as described in our case 1, must be considered a radiological finding of risk for "de novo" aneurysm formation.     

Clinical and experimental investigation of pseudoaneurysm in the anterior communicating artery area on 3-dimensional time-of-flight cerebral magnetic resonance angiography

OBJECTIVE: To investigate the hemodynamic mechanism of pseudoaneurysm in the anterior communicating artery (AcoA) area in magnetic resonance (MR) angiography. METHODS: For the clinical study, a total of 62 patients who undertook digital subtraction angiography (DSA) because of the rupture of an aneurysm originating from a location other than the AcoA area were examined with MR angiography. The relation between signal defect at the AcoA in MR angiography and anatomic variation of the anterior cerebral artery (ACA) was evaluated. For the experimental study, MR angiography and DSA were performed on elastic silicon vascular phantoms with 2 different bifurcation angles (70 degrees and 140 degrees). Hemodynamic factors producing signal defects were evaluated, and the results were compared by computational fluid dynamics (CFD). RESULTS: In a clinical study, 21 of 62 patients had a hypogenetic A1 segment on either side of the ACA. Their MR angiography showed signal defects in the axilla area of the bifurcated AcoA complex in 14 patients, 7 of which could make the residual normal vessel seem to be an aneurysm. All the cases with an intact AcoA complex showed no signal defect. In an experimental study, MR angiography of vascular phantoms with broad-angle bifurcation (140 degrees) showed signal defects at the axilla areas of bifurcation, and these were shown as turbulent flow in DSA and CFD. Phantoms with narrow-angle bifurcation (70 degrees) did not show a significant signal defect, however. CONCLUSIONS: A hypoplastic A1 segment accompanying a broad bifurcation angle of the contralateral A1 segment may cause a pseudoaneurysm in MR angiography because of signal defect in the AcoA area.     

前交通动脉瘤与大脑前动脉A1段缺如相关性研究

目的：探讨前交通动脉瘤（ACoA）发病及伴蛛网膜下腔出血与大脑前动脉A1段缺如的相关性。方法：回顾性分析705例全脑血管造影及临床资料,其中47例ACoA患者为研究组,129例无脑血管病变患者为对照组,比较ACoA发病、动脉瘤大小及蛛网膜下腔出血与大脑前动脉A1段缺如相关性。结果：47例ACoA患者中,大脑前动脉A1段缺如发生率为44.7%,对照组129例患者中大脑前动脉A1段缺如发生率为9.3%,ACoA患者伴大脑前动脉A1段缺如发生率明显高于对照组,差异有显著性意义（χ^2=28.303,P〈0.001）。21例伴A1段缺如的ACoA动脉瘤平均直径（5.8±2.8）mm,26例无A1段缺如的ACoA动脉瘤平均直径（4.2±2.2）mm,二者差异有显著性意义（t=2.098,P〈0.05）。21例伴A1段缺如的ACoA,其蛛网膜下腔出血程度与大脑前动脉A1段缺如相关（Z=-2.199,P〈0.05）。结论：前交通动脉瘤发病、动脉瘤大小以及伴发蛛网膜下腔出血均与大脑前动脉A1段缺如相关,大脑前动脉A1段缺如患者的ACoA发生率明显增高。     

Infraoptic anterior cerebral artery or carotid–anterior cerebral artery anastomosis: A very rare embryological variation. Case series and review of literature

PurposeAn infraoptic course of the anterior cerebral artery (ACA) is a rare cerebrovascular variation that can be associated with anterior communicating artery aneurysm. The purpose of this study is: 1. Describe infraoptic ACA or Carotid-ACA anastomosis. 2. Discuss the embryology. 3. Demonstrate this rare variation on CT/MR angiography. 4. Discuss its clinical significance. 5. Understand the anatomy for appropriate management of associated vascular pathology (Anterior communicating aneurysm). 6. Literature review.MethodsWe describe 2 cases with CT/MR angiographic findings of this rare vascular variation along with review of embryology and literature.Results and conclusionGenerally, ACA arises from the internal carotid artery (ICA) terminus and runs medially superior to the optic nerves and communicates with contralateral ACA through the anterior communicating artery. An infraoptic course of the A1 segment of the ACA is associated with a low ICA bifurcation, usually located intradurally at or just above the level of the origin of the ophthalmic artery. Rarely, infraoptic origins of A1 are proximal or at the level of origin of the ophthalmic arteries and arise below the optic strut possibly extradurally. Abberant ACA course has been shown to be associated with aneurysms which needs prompt recognition, to allow optimum treatment planning (surgical/endovascular). Our first case has bilateral infraoptic ACA seen on CT angiography. The second case has ipsilateral (right) infraoptic ACA with associated anterior communicating artery aneurysm.     

Fenestrations of Intracranial Arteries

BACKGROUND AND PURPOSE:Few data are available on the frequency and location distribution of fenestrations of intracranial arteries. We used 3D rotational angiography of all intracranial arteries in a cohort of 179 patients with suspected intracranial aneurysms to assess the prevalence and location of fenestrations and the relation of fenestrations to aneurysms.MATERIALS AND METHODS:Of 179 patients with subarachnoid hemorrhage admitted between March 2013 and June 2014, 140 had 3D rotational angiography of all cerebral vessels. The presence and location of aneurysms and fenestrations were assessed. In patients with both aneurysms and fenestrations, we classified the relation of the location of the aneurysm as remote from the fenestration or on the fenestration.RESULTS:In 140 patients, 210 aneurysms were present. In 33 of 140 patients (24%; 95% confidence interval, 17.2%–31.3%), 45 fenestrations were detected with the following locations: anterior communicating artery in 31 (69%), A1 segment of the anterior cerebral artery in 4 (9%), middle cerebral artery in 4 (9%), basilar artery in 4 (9%), vertebral artery in 1 (2%), and anterior inferior cerebellar artery in 1 (2%). Of 56 patients with anterior communicating artery aneurysms, 14 had a fenestration on the anterior communicating artery complex. The remaining 31 fenestrations had no anatomic relation to aneurysms. In 140 patients with 210 aneurysms, 14 aneurysms (7%) were located on a fenestration and 196 were not.CONCLUSIONS:In patients with a suspected ruptured aneurysm, fenestrations of intracranial arteries were detected in 24% (33 of 140). Most fenestrations were located on the anterior communicating artery. Of 45 fenestrations, 14 (31%) were related to an aneurysm.

Fenestrations of intracranial arteries are segmental duplications of the lumen into 2 distinct channels, each comprising endothelial and muscular layers with or without a shared adventitia. Fenestrations are anatomic variants and can range from a small focus of divided tissue to duplication of a long vessel segment.^1,2Fenestrations result from partial failure of fusion of paired primitive embryologic vessels or from incomplete obliteration of anastomosis in a primitive vascular network.²The association of fenestrations with aneurysms and other neurovascular disorders has been noted. Some suggest that altered flow dynamics in the presence of fenestrations may promote aneurysm development, though the exact relationship is not well-defined.Surgical and anatomic studies suggest that fenestrations are common in intracranial arteries with the highest prevalence in the anterior communicating artery (AcomA) complex.^3–5 Demonstration of fenestrations with imaging is uncommon.^6,7 Most fenestrations are only visible from a specific viewing angle that is often not provided by conventional angiography or reconstructed cross-sectional imaging. With 3D imaging, especially 3D rotational angiography, the detection rate of fenestrations has improved.⁸ Scant data are available on the frequency and location distribution of fenestrations of intracranial arteries, to our knowledge. We used 3D rotational angiography of all intracranial arteries in a cohort of 179 patients with suspected intracranial aneurysms to assess the prevalence and location of fenestrations and the relation of fenestrations with aneurysms.     

Improved image quality of intracranial aneurysms: 3.0-T versus 1.5-T time-of-flight MR angiography

BACKGROUND AND PURPOSE: We hypothesize that the nearly doubling of signal-to-noise ratio at 3.0 T compared with that at 1.5 T yields improved clinical MR angiograms and enables superior visualization of intracranial aneurysms. The goal of this study was to determine whether 3.0-T time-of-flight (TOF) MR angiography is superior to 1.5-T TOF MR angiography in the detection and characterization of intracranial aneurysms. METHODS: Fifty consecutive patients referred for MR angiography of a known or suspected intracranial aneurysm underwent 3-T TOF MR angiography. Seventeen of these 50 patients had also previously undergone 1.5-T TOF MR angiography and these images were used as a basis for comparison with images obtained at 3.0 T. Fourteen of 23 patients in whom aneurysms were identified also underwent prior conventional angiography, which was used as the reference standard. Readers blinded to patient history identified the presence and location of aneurysm(s) on angiograms and graded images for overall image quality by using a five-point scale. RESULTS: Twenty-eight aneurysms were identified in 23 of 50 patients. Seventeen aneurysms in 17 patients had been documented with 1.5-T MR angiography. The 3.0-T technique had a higher mean image quality score than that of the 1.5-T MR technique (P <.0001). Both 3.0-T and 1.5-T TOF MR angiography depicted all the aneurysms that had been documented by conventional angiography. CONCLUSION: 3D TOF MR angiography at 3 T offers superior depiction of intracranial aneurysms compared with that of 1.5-T TOF MR angiography.     

Time-of-Flight Magnetic Resonance Angiography for Follow-Up of Coil Embolization with Enterprise Stent for Intracranial Aneurysm: Usefulness of Source Images

Objective

The aim of this study was to determine the interobserver and intermodality agreement in the interpretation of time-of-flight (TOF) MR angiography (MRA) for the follow-up of coiled intracranial aneurysms with the Enterprise stent.

Materials and Methods

Two experienced neurointerventionists independently reviewed the follow-up MRA studies of 40 consecutive patients with 44 coiled aneurysms. All aneurysms were treated with assistance from the Enterprise stent and the radiologic follow-up intervals were greater than 6 months after the endovascular therapy. Digital subtraction angiography (DSA) served as the reference standard. The degree of aneurysm occlusion was determined by an evaluation of the maximal intensity projection (MIP) and source images (SI) of the TOF MRA. The capability of the TOF MRA to depict the residual flow within the coiled aneurysms and the stented parent arteries was compared with that of the DSA.

Results

DSA showed stable occlusions in 25 aneurysms, minor recanalization in 8, and major recanalization in 11. Comparisons between the TOF MRA and conventional angiography showed that the MIP plus SI had almost perfect agreement (κ = 0.892, range 0.767 to 1.000) and had better agreement than with the MIP images only (κ = 0.598, range 0.370 to 0.826). In-stent stenosis of more than 33% was observed in 5 cases. Both MIP and SI of the MRA showed poor depiction of in-stent stenosis compared with the DSA.

Conclusion

TOF MRA seemed to be reliable in screening for aneurysm recurrence after coil embolization with Enterprise stent assistance, especially in the evaluation of the SI, in addition to MIP images in the TOF MRA.     

MR angiography and surgery for unruptured familial intracranial aneurysms in persons with a family history of cerebral aneurysms.

OBJECTIVE: We used MR angiography to determine prevalence of unruptured familial intracranial aneurysms in a prepaid medical care program. We compared surgical outcomes and the cost of treating unruptured versus ruptured aneurysms. We compared the cost of MR angiography with the cost of screening mammography and with the cost of surgically treating a ruptured aneurysm. SUBJECTS AND METHODS: During a 30-month period, we performed MR angiography to show cerebral aneurysms in 63 surgical candidates who had one or more first-degree relatives with an aneurysm. Unruptured aneurysms seen on MR angiography were evaluated by digital subtraction angiography (DSA) and treated surgically. RESULTS: MR angiography showed nine unruptured aneurysms in six patients. Eight aneurysms were seen on MR angiography and nine were seen on DSA. Seven unruptured aneurysms were treated surgically. The mean treatment cost was 50% lower for an unruptured aneurysm than that for a ruptured aneurysm. No patient surgically treated for an unruptured aneurysm required rehabilitation, unlike 25% of patients with ruptured aneurysms. The annual total cost of MR angiography was equivalent to 2.9% of the annual cost of screening mammography. The annual cost of MR angiography equaled half the cost of treating one patient after aneurysm rupture. CONCLUSION: MR angiography showed a 9.5% prevalence of unruptured aneurysms among persons who had one or more first-degree relatives with a cerebral aneurysm. DSA confirmed 88% of aneurysms found on MR angiography. Persons with unruptured aneurysms had better treatment outcomes at lower cost than did patients treated for aneurysm rupture. The annual MR angiography cost was low compared with the cost of screening mammography and with the cost of treating one patient with aneurysm rupture.     

Supraclinoid internal carotid artery fenestration from which the posterior communicating artery arising with infundibular dilatation at its origin diagnosed by magnetic resonance angiography

A 72-year-old man with vertigo underwent cranial magnetic resonance (MR) imaging and MR angiography using a 3.0-Tesla scanner. MR angiography showed an aneurysm-like lateral protrusion from the left supraclinoid internal carotid artery (ICA) and infundibular dilatation of the left posterior communicating artery at its origin. After creating both partial maximum-intensity-projection images and partial volume-rendering images, a fenestration of the supraclinoid ICA was found. The posterior communicating artery arose from the fenestrated segment, and its origin was dilated triangularly, indicating infundibular dilatation. Cerebral arterial fenestration is not so rare, but it is rarely found at the ICA. The majority of recently reported cases had an associated aneurysm at the proximal end of the fenestration diagnosed using three-dimensional rotational angiography (3DRA). MR angiography is noninvasive and widely used for the screening of cerebral arterial lesions. Even though 3.0-Tesla scanner, special resolution of MR angiography is much lower than that of the 3DRA. For the diagnosis and confirmation of this rare variation, partial maximum-intensity-projection images and/or partial volume-rendering images are useful.     

Computed tomography angiography in detection and characterization of ruptured anterior cerebral artery aneurysms at uncommon location for emergent surgical clipping

INTRODUCTION: Cerebral subarachnoid hemorrhage may result from rupture of saccular aneurysms at uncommon location [excluding the anterior communicating artery (ACOM)] of the anterior cerebral artery (ACA). The purpose of this study was to evaluate the usefulness of helical computed tomography angiography (CTA) in detection and characterization of intracranial aneurysms at such uncommon locations before emergent surgical clipping. MATERIALS AND METHODS: Between 1998 and 2003, records for 50 consecutive patients who underwent emergent surgical clipping for intracranial aneurysms were reviewed. Eighteen of these patients had aneurysms in the ACA. After those patients with unequivocal ACOM aneurysms were excluded, eight patients with eight aneurysms in an uncommon location of the ACA were recruited to this study. Plain computed tomography (CT) and CTA were performed in eight patients, and digital subtraction angiographies were done in three patients. Each aneurysm was evaluated for the detection, quantification, and characterization of the aneurysms with 2D multiplanar reformatted and 3D volume-rendering techniques. RESULTS: There were two small aneurysms arising from the A1 segment, one from the A2 segment, two at the junction of triplicated ACAs, two at the junction of A2 and A3 segments, and one at the junction of A2 and A3 segments of the azygos ACA. The average diameter of the aneurysmal sac was 4.44 mm (range, 2.7-7.0 mm), and the aneurysmal neck averaged 2.59 mm (range, 1.2-3.5 mm) in size. The smallest aneurysm measured 2.2x1.8x2.7 mm (neck, 1.2 mm) in the A1 segment of the left ACA. Three patients had intracerebral hematoma, seven had intraventricular hemorrhage, and three had acute hydrocephalus. CONCLUSION: Aneurysms in uncommon locations of ACAs exhibited characteristic features. Rupture of these aneurysms can cause intracerebral hematoma, intraventricular hemorrhage, and/or acute hydrocephalus. Noninvasive CTA can reliably detect and characterize intracranial aneurysms at such uncommon location for planning of emergent surgical intervention.     

The role of MR angiography in the pretreatment assessment of intracranial aneurysms: a comparative study

BACKGROUND AND PURPOSE: With developments in coil technology, intracranial aneurysms are being treated increasingly by the endovascular route. Endovascular treatment of aneurysms requires an accurate depiction of the aneurysm neck and its relation to parent and branch vessels preoperatively. Our goal was to estimate the clinical efficacy of MR angiography (MRA) in the pretreatment assessment of ruptured and unruptured intracranial aneurysms. We compared MRA source data (axial acquired partitions), multiplanar reconstruction (MPR) of these data, as well as maximum intensity projection (MIP) and 3D-isosurface images with intraarterial digital subtraction angiography (IA-DSA). METHODS: The study was performed in 29 patients with 42 intracerebral aneurysms. The MRA data were examined in four different forms--as axial source data, MPR images of the source data, and MIP and 3D isosurface--rendered images. A composite standard of reference for each aneurysm was then constructed using this information together with the IA-DSA findings by looking at aneurysm detection rate, aneurysm morphology, neck interpretation, and branch vessel relationship to the aneurysm. All techniques, including conventional IA-DSA, were then scored independently on a five-point scale from 1 (non diagnostic) to 5 (excellent correlation with the standard of reference) for each of the aneurysm components as compared with the composite picture. An overall score for each technique was also obtained. RESULTS: Of the 42 aneurysms examined, 34 were small (<10 mm), six were large (10-25 mm), and two were giant (>25 mm). Three aneurysms were not detected with MRA. These were smaller than 3 mm and either in an anatomically difficult location (middle cerebral artery bifurcation) or obscured by adjacent hematoma. Two large aneurysms were depicted as undersized by IA-DSA owing to the presence of intramural thrombus shown by MRA axial source data. IA-DSA received the highest scores overall and in three of the four subgroups. Three-dimensional isosurface reconstructions scored higher than did IA-DSA for depiction of the aneurysm neck, although this difference was not significant. The MPR and 3D-isosurface images were comparable to those of IA-DSA in all categories. MPR images were particularly useful for defining branch vessels and the aneurysm neck. MIP images scored poorly in all subgroups (P < .005) compared with IA-DSA findings, except for in aneurysm detection. Source data images were significantly inferior to those of IA-DSA in all categories (P < .005). CONCLUSION: MRA is currently inferior to IA-DSA in pretreatment assessment of intracranial aneurysms, and can miss small lesions (<3 mm). It can, however, provide complementary information to IA-DSA, particularly in anatomically complex areas or in the presence of intramural thrombus. If MRA is used in aneurysm assessment, a meticulous technique with reference to both axial source data and MPR is mandatory. The axial source data should not be interpreted in isolation. Three-dimensional isosurface images are comparable to those of IA-DSA and are more reliable than are MIP images, which should be interpreted with caution.     

Basilar artery fenestration detected with CT angiography

Objectives

To analyse the characteristics of basilar artery (BA) fenestrations and their coexistence with aneurysms and other anomalies in a massive cases by computed tomographic angiography (CTA).

Methods

A total of 5,657 sequential cerebral CTA images performed from January 2006 to February 2012 were reviewed. CTA images were obtained from the raw datasets by using volume rendering and maximal intensity projection reconstruction.

Results

One hundred and thirty-two (2.33 %) BA fenestrations were detected with CTA, and most common at the proximal segment (n?=?124). BA fenestration-associated aneurysms were found in 34 cases and 7 located at the posterior circulation, and the frequency of posterior circulation aneurysms was significantly different in patients with and without BA fenestrations (P?=?0.025). Other associated anomalies included arteriovenous malformation (n?=?7) and moyamoya disease (n?=?6). BA fenestrations were classified into Type I (74 cases), Type II (15 cases), Type III (41 cases) and Type IV (2 cases). A significant difference was observed between Types II + III associated with convex-lens-like and slit-like fenestrations (P?=?0.008).

Conclusions

BA fenestrations were found in 2.33 % with CTA. They were significantly more often associated with posterior circulation aneurysms than those without BA fenestration. The anterior inferior cerebral artery (AICA) tends to originate more often from convex-lens-like fenestration than slit-like.

Key Points

? Basilar artery fenestrations were found in 2.33?% of patients undergoing CT angiography. ? Fenestrations were seen more often in the lower third with slit-like configurations. ? No obvious relationship exists between basilar artery fenestration and aneurysm formation. ? Basilar artery fenestrations perhaps predispose a patient to posterior circulation aneurysm formation. ? The AICA tends to originate more often from convex-lens-like than slit-like fenestrations.