Contrast-enhanced MR angiography of intracranial giant aneurysms

BACKGROUND AND PURPOSE: Intravoxel phase dispersion and flow saturation often prevent adequate depiction of intracranial giant aneurysms on 3D time-of-flight (3D-TOF) MR angiography (MRA). Additional diagnostic difficulties may arise from T1 contamination artifact of an associated blood clot. Our aim was to assess whether contrast-enhanced MRA could improve the evaluation of giant aneurysms and to compare two different types of contrast-enhanced MRA. METHODS: We studied 11 aneurysms in 10 patients (age range, 31-77 years) with giant aneurysms of the anterior (n = 9) and posterior (n = 2) cerebral circulation by comparing 3D-TOF, first-pass dynamic contrast-enhanced MRA, and steady-state contrast-enhanced 3D-TOF sequences. Additional comparison with digital subtraction angiography (DSA) was performed in eight aneurysms. RESULTS: In nine of 11 aneurysms, 3D-TOF did not adequately show the lumen and exiting vessels. Contrast-enhanced 3D-TOF and dynamic contrast-enhanced MRA showed the aneurysm sac and exiting vessels in all of these cases. Dynamic contrast-enhanced MRA showed a better intravascular contrast than did contrast-enhanced 3D-TOF, which led to better delineation of the aneurysms. T1 contamination artifact from intra- or extraluminal blood clot was evident on the 3D-TOF images in four cases. The artifact was less marked on the contrast-enhanced 3D-TOF image and was completely eliminated on the dynamic contrast-enhanced MRA image by subtraction of precontrast images. The diagnostic information provided by dynamic contrast-enhanced MRA was comparable to that provided by DSA. CONCLUSION: Precontrast 3D-TOF is inadequate for the assessment of giant cerebral aneurysms. Both contrast-enhanced 3D-TOF and dynamic contrast-enhanced MRA reliably show the aneurysm sac and connected vessels. Dynamic MRA provides a superior contrast between flow and background and eliminates T1 contamination artifact. It should therefore be considered as the MRA sequence of choice.     

The role of time-resolved 3D contrast-enhanced MR angiography in the assessment and grading of cerebral arteriovenous malformations

Purpose

To assess the role of three-dimensional (3D) contrast-enhanced, time-resolved MR angiography (CE TR MRA) in patients with intracranial arteriovenous malformations (AVMs).

Methods

We studied 12 patient with intracranial AVMs on a 3.0 T MR imaging system (Magentom TIM Trio, Siemens Medical Solutions, Erlangen, Germany) using 3D CE TR MRA with autocalibrating partially parallel acquisitions and echo sharing schemes, which provided temporal resolution of 0.58 or 1.7 s and near isotropic voxels. We qualitatively assessed image quality of the 3D CE TR MRA and compared the grading of the AVMs based on modified Spetzler-Martin system for 3D CE TR MRA and catheter digital subtraction angiography (DSA).

Results

CE TR MRA provided good quality images in the 3 standard orthogonal planes, and good arterial-venous separation in all cases. All AVMs were correctly graded by CE TR MRA when compared with DSA.3D CE TR MRA provides a non-invasive alternative to DSA for the evaluation of cerebral AVMs.     

Follow-up of intracranial aneurysms treated with detachable coils: comparison of 3D inflow MRA at 3T and 1.5T and contrast-enhanced MRA at 3T with DSA

Introduction  The purpose of this prospective study was to compare 3T and 1.5T magnetic resonance angiography (MRA) with digital subtraction angiography (DSA) for the follow-up of endovascular treated intracranial aneurysms to assess the grade of occlusion. Materials and methods  Thirty-seven patients with 41 aneurysms who had undergone endovascular treatment with detachable coils were included. MRA was performed on the same day using an eight-channel sensitivity encoding head-coil with 3D axial inflow technique. At 3T, a contrast-enhanced transverse 3D fast gradient echo acquisition was also performed. Most patients underwent DSA the following day. MRA scans and DSA were classified first independently by two neuroradiologists and an interventional neuroradiologist. Secondly, a consensus was done. Source images, maximum intensity projection, multiplanar reconstruction and volume rendering reconstructions were used for MRA evaluations. A modification of the Raymond classification, previously used for DSA evaluation of recanalization, was used. Results  Statistical comparison of the consensus showed that 3T MRA with 3D axial inflow technique had better agreement with DSA (κ = 0.43) than 1.5T MRA(κ = 0.21) and contrast-enhanced MRA (CE-MRA) at 3T (κ = 0.17). The susceptibility artefacts from the coil mesh were significally smaller at 3T (p = 0.002–0.007) than at 1.5T. Conclusion  3T MRA, using a sensitivity encoding head-coil, showed better agreement with DSA than 1.5T and CE-MRA at 3T for evaluation of aneurysms treated with endovascular coiling.     

Acute subarachnoid Haemorrhage: 3D time-of-flight MR angiography versus intra-arterial digital angiography

To evaluate the efficacy and reliability of 3D time-of-flight MR angiography (TOF MRA) as a noninvasive procedure, 27 patients with acute subarachnoid haemorrhage (SAH) were studied with MRA immediately before or after intra-arterial digital subtraction angiography (DSA). 3DTOF MRA was performed with an axial slab of 60 mm centred on the circle of Willis and isotropic voxels. DSA showed 22 aneurysms and 1 dural arteriovenous fistula in 21 patients; the aneurysms ranged in size from 2 to 8 mm. MRA failed to show 2 small aneurysms, at the origin of the posterior and anterior communicating arteries. The 3D display of the intracranial vessels obtained with maximum intensity projection (MIP) or targetted MIP sometimes rendered the aneurysms better than DSA. However, due to its high spatial resolution, DSA more clearly defined the overall anatomy of the walls of the normal and abnormal vessels.1992 Scientific Award of the ESNR     

Follow-up of coiled intracranial aneurysms: comparison of 3D time-of-flight and contrast-enhanced magnetic resonance angiography at 3T in a large, prospective series

Objectives

To compare 3D-TOF magnetic resonance angiography (MRA) and contrast-enhanced MRA (CE-MRA) sequences at 3T in the follow-up of coiled aneurysms with digital subtracted angiography (DSA) as the gold standard.

Methods

DSA, 3D-TOF and CE-MRA were performed in a prospective series of 126 aneurysms in 96 patients (57 female, 39 male; age: 25–75 years, mean: 51.3?±?11.3 years). The quality of aneurysm occlusion was assessed independently and anonymously by a core laboratory.

Results

Using DSA (gold standard technique), total occlusion was depicted in 57 aneurysms (45.2%), neck remnant in 34 aneurysms (27.0%) and aneurysm remnant in 35 aneurysms (27.8%). Sensitivity, specificity, positive predictive value and negative predictive value were very similar with 3D-TOF and CE-MRA. Visibility of coils was much better with 3D-TOF (95.2%) than with CE-MRA (23.0%) (P?P?=?0.012).

Conclusions

In this large prospective series of patients with coiled aneurysms, at 3T 3D-TOF MRA was equivalent to CE-MRA for the evaluation of aneurysm occlusion, but coil visibility was superior at 3D-TOF. Thus the use of 3D-TOF at 3T is recommended for the follow-up of coiled intracranial aneurysms.

Key Points

? Different Magnetic Resonance (MR) imaging techniques are used to evaluate intracranial aneurysms. ? At 3T MR, 3D-TOF and CE-MRA appear equivalent for evaluating coiled aneurysms.. ? Coils are better visualised on 3D-TOF than on CE-MRA. ? Combined analysis of 3D-TOF and CE-MRA does not seem helpful. ? At 3T, 3D-TOF techniques are recommended for monitoring patients with coiled aneurysms.     

Contrast-Enhanced Time-Resolved MRA for Follow-Up of Intracranial Aneurysms Treated with the Pipeline Embolization Device

BACKGROUND AND PURPOSE:Endovascular reconstruction and flow diversion by using the Pipeline Embolization Device is an effective treatment for complex cerebral aneurysms. Accurate noninvasive alternatives to DSA for follow-up after Pipeline Embolization Device treatment are desirable. This study evaluated the accuracy of contrast-enhanced time-resolved MRA for this purpose, hypothesizing that contrast-enhanced time-resolved MRA will be comparable with DSA and superior to 3D-TOF MRA.MATERIALS AND METHODS:During a 24-month period, 37 Pipeline Embolization Device–treated intracranial aneurysms in 26 patients underwent initial follow-up by using 3D-TOF MRA, contrast-enhanced time-resolved MRA, and DSA. MRA was performed on a 1.5T unit by using 3D-TOF and time-resolved imaging of contrast kinetics. All patients underwent DSA a median of 0 days (range, 0–68) after MRA. Studies were evaluated for aneurysm occlusion, quality of visualization of the reconstructed artery, and measurable luminal diameter of the Pipeline Embolization Device, with DSA used as the reference standard.RESULTS:The sensitivity, specificity, and positive and negative predictive values of contrast-enhanced time-resolved MRA relative to DSA for posttreatment aneurysm occlusion were 96%, 85%, 92%, and 92%. Contrast-enhanced time-resolved MRA demonstrated superior quality of visualization (P = .0001) and a higher measurable luminal diameter (P = .0001) of the reconstructed artery compared with 3D-TOF MRA but no significant difference compared with DSA. Contrast-enhanced time-resolved MRA underestimated the luminal diameter of the reconstructed artery by 0.965 ± 0.497 mm (27% ± 13%) relative to DSA.CONCLUSIONS:Contrast-enhanced time-resolved MRA is a reliable noninvasive method for monitoring intracranial aneurysms following flow diversion and vessel reconstruction by using the Pipeline Embolization Device.

Surgical clipping or endovascular coil embolization is generally the preferred treatment for intracranial aneurysms.¹ The Pipeline Embolization Device (PED; Covidien, Irvine, California) is an endovascular device that has redefined the scope of treatment for large, giant, wide-neck, or fusiform aneurysms or aneurysms having failed coil embolization, by reconstructing the parent artery and restoring its natural course.² The PED is designed for 85% reduction of blood flow within an aneurysm, which induces thrombosis² while keeping perforators and/or side branch vessels patent.³ Results from a multicenter prospective trial for treatment of uncoilable or failed large and giant ICA aneurysms with the PED demonstrated 99% technical success and 74% complete occlusion with 6% major ipsilateral stroke or death.⁴ Flow diversion with the PED has also been reported in the treatment of HIV vasculopathy, with fusiform cerebral aneurysms precluding parent vessel sacrifice or surgical bypass.⁵Digital subtraction angiography is the reference standard for the evaluation of aneurysms after endovascular treatment due to its unsurpassed spatial resolution; however, DSA is invasive and not without risks of puncture site and neurologic complications.⁶ Posttreatment follow-up of intracranial aneurysms after coil embolization with MRA by using 3D-TOF or contrast-enhanced techniques is a potential noninvasive alternative to DSA for the evaluation of PED-treated aneurysms without the use of ionizing radiation.⁷ Contrast-enhanced time-resolved MRA (CE-TR MRA) uses acquisition schemes aimed at accelerated data collection, primarily using parallel imaging algorithms and novel k-space trajectories to achieve high temporal resolution for multiphasic MRA examinations. This technique provides consistent, technologist-independent, optimal arterial enhancement for contrast-enhanced MRA and provides information on temporal contrast kinetics.^8,9 Use of CE-TR MRA has been reported in the evaluation of intracranial lesions such as arteriovenous malformations and dural arteriovenous fistulas and for assessment of stenosis of the extracranial carotid artery, and it seems to be a promising technique for evaluating aneurysms after stent-assisted coil embolization.^9–11We hypothesized that TR-CE MRA could provide information comparable with DSA and would be superior to 3D-TOF MRA in the evaluation of intracranial aneurysms and the parent artery following flow diversion and parent vessel reconstruction with the PED.     

Contrast-enhanced magnetic resonance angiography in peripheral arterial disease: improving image quality by automated image registration

In peripheral arterial disease, contrast-enhanced MR angiography (MRA) is a noninvasive imaging alternative for catheter-based digital subtraction angiography (DSA). In DSA, final images are generated by subtracting a native mask image from subsequent contrast-enhanced images. Image quality is routinely improved by digitally shifting the mask image prior to subtraction if the patient has moved during angiography. This study investigated whether such image registration may also help to improve the image quality of MRA. In all, 545 MRA examinations of pelvic and leg arteries in patients with symptoms of peripheral arterial disease were studied retrospectively. Standard nonregistered MRA was compared to automatically linear, affine, and warp registered MRA by visual analysis and by three image quality parameters, including vessel detection probability (VDP) of angiographic maximum intensity projections. Most MRA of pelvic and upper leg arteries showed good nonregistered image quality. However, the 15% of lower legs with a body shift of 1 mm or more had relatively low nonregistered image quality, which improved significantly with image registration (VDP gain more than 18%, P < 0.05). The visual analysis gave similar results. In conclusion, image registration can improve image quality of MRA in peripheral arterial disease, especially in the lower legs.     

Intracranial vascular stenosis and occlusion: comparison of 3D time-of-flight and 3D phase-contrast MR angiography

We compared the value of 3D time-of-flight (TOF) and phase-contrast (PC) MR angiography (MRA) for detection and grading of intracranial vascular steno-occlusive disease. Unenhanced 3D-TOF MRA and 3D-PC MRA (30–60 cm/s velocity encoding) were performed at the level of the circle of Willis in 18 patients, mean age 56 ± 10 years. Postprocessed images using a maximum-intensity projection reconstruction with multiple targetted projections were analysed. A total of 126 vessels was assessed by PC MRA and 143 by TOF MRA, with digital subtraction angiography (DSA) in 15 patients and/or transcranial Doppler sonography (TCD) in 18 as a standard. Two blinded readers reviewed the MRA, DSA and TCD examinations retrospectively. On DSA and/or TCD the two observers found 32 and 28 steno-occlusive lesions. 3D-TOF MRA was more sensitive than 3D-PC MRA (87 % and 86 % vs. 65 % and 60 %) and had a higher negative predictive value (96 % vs. 89 %). Correct grading of stenoses was achieved in 78 % by 3D-TOF and 65 % by 3D-PC MRA. Received: 24 September 1997 Accepted: 27 February 1998     

Contrast-enhanced MR angiography of the supra-aortic vessels in 24 seconds: a feasibility study

A contrast-enhanced, gradient-echo 3D pulse sequence providing angiographic information in 24 s was tested in five healthy subjects and used prospectively in 21 patients for the investigation of the cervical arteries. Indications included suspected stenosis of the carotid (in 13), or vertebral arteries (in 1), carotid dissection (3), variants of the branches of the aortic arch (2) and extracranial carotid aneurysms (2). The results in all patients were compared with those of intra-arterial digital subtraction angiography (DSA). In patients with carotid stenosis, they were also compared with high-resolution 3D time-of-flight (TOF) MR angiography (MRA). Good quality MR angiograms of the neck vessels were obtained with the fast 3D sequence in 20 of the 21 patients. One claustrophobic patient was unable to co-operate. The degree of internal carotid artery (ICA) stenosis was graded correctly (compared to DSA) in 21 of 24 cases (87.5 %). Two mild stenoses were overestimated as moderate using the fast MR sequence and one high-grade stenosis was misdiagnosed as a complete occlusion. Carotid dissection was confirmed in one case and correctly excluded in two. Four extracranial ICA aneurysms in two patients, arterial variants and stenosis of the origin of the vertebral artery were correctly diagnosed using the contrast-enhanced MR angiogram. Three-dimensional TOF MRA was unsuccessful due to motion artefacts in half of the cases of ICA stenosis. Received: 6 August 1998 Accepted: 21 December 1998     

连续三维时飞法磁共振血管成像对脑动脉的显示能力评价

目的评价连续3D-TOF和高速度编码的三维相位对比法(Venc3D-PC)MRA对脑动脉的显示能力。方法前瞻性选取脑MRI表现正常且连续3D-TOF及高Venc3D-PC磁共振脑动脉成像表现正常者15例,用以评价2种MRA技术显示脑动脉的差异。回顾性选取进行脑动脉MRA及DSA2种检查者43例,以DSA为标准,取其中38侧表现正常者用以评价MRA显示脑动脉的能力。结果3D-TOF与高Venc3D-PC技术显示ACA、MCA或PCA的最大级数均无显著统计学差异,但前者的图像质量优于后者。MRA显示ACA、MCA和PCA的分支级数与DSA均有显著差异性。MRA对ACA和MCA的显示能力均较DSA减少1个级别,对PCA的显示能力差别不大。结论连续3D-TOFMRA对脑动脉的显示能力小于DSA,但已能满足大多数脑血管疾病的临床应用。     

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.     

Surveillance of intracranial aneurysms treated with detachable coils: a comparison of MRA techniques

Two MRA techniques were evaluated for the follow-up of coiled intracranial aneurysms. Twenty-nine coiled aneurysms were evaluated for a total of 36 follow-up assessments using 3D time-of flight MRA (TOF MRA), an auto-triggered elliptic–centric-ordered three-dimensional gadolinium-enhanced MR angiogram (ATECO MRA), as well as a selective digital subtraction angiography (DSA), which served as the gold standard. Confident visualization was seen in 36 (100%) of ATECO MRAs and in 32 (89%) of the TOF MRAs. Eleven residual aneurysm components (RACs) greater than 2 mm were described on DSA. Of these, nine were seen on ATECO MRA (sensitivity of 81% and specificity of 88%) and four were seen on TOF MRA (sensitivity of 40% and specificity of 90%). The two RACs not seen on ATECO MRA both measured 3 mm. The six RACs not seen on TOF MRA measured 3, 4 and 5 mm. ATECO MRA provides a non-invasive reliable angiogram for the surveillance of coiled aneurysms and is superior to TOF MRA for this purpose.     

Contrast-enhanced MR 3D angiography in the assessment of brain AVMs

BACKGROUND AND PURPOSE: Digital subtraction angiography (DSA) is the current reference standard for the diagnosis, assessment, and management of brain arteriovenous malformations (AVMs). The purpose of this study was to compare the diagnostic utility of three-dimensional (3D) time-of-flight (TOF) magnetic resonance angiography (MRA) and contrast-enhanced 3D MRA in patients with intracranial arteriovenous malformations (AVMs) in different sizes and locations. The AVM diagnosis was proved via DSA and almost half of the patients had also hematoma. MATERIALS AND METHODS: Two radiologists, experienced on neurovascular imaging and independent from each other, retrospectively reviewed two MRA techniques and DSA with regard to the assessment of feeding arteries, AVM nidus, and venous drainage patterns on 20 patients with 23 examinations by scoring system. Disagreements were resolved by consensus. RESULTS: An excellent agreement between contrast-enhanced MRA and DSA was found in order to assess the numbers of arterial feeders and draining veins (Spearman r=0.913, P<0.001). The average scores in contrast-enhanced MRA for feeders, nidi, and drainers were respectively 2.26, 2.69, and 2.48, while in TOF-MRA they are 1.96, 1.35, and 0.89, respectively. CONCLUSION: Compared to TOF-MRA, 3D contrast-enhanced MRA is useful for visualization by subtraction technique of malformation components presented by hematoma or by haem product. On the other hand, for the cases presented by slow or complex flow that is especially in around or nidi or around the venous portion is also advantageous because of the independence from flow-related enhancement. Therapeutic effects were clearly demonstrated in three follow-up patients. A major limitation of this technique is the low spatial resolution. Since there is such a limitation, arterial feeder of a case with micro-AVM is not detected by contrast-enhanced MRA and nidus for the same case was observed retrospectively. In this respect, we believe that 3D contrast-enhanced MRA is a less invasive and inexpensive angiographic tool, but not a safe substitute for DSA. Yet, it can be a beneficial supplement to DSA in patients with cerebral AVMs at both initial diagnosis and at follow-up processes after therapy.     

Time-of-flight MR angiography targeted to coiled intracranial aneurysms is more sensitive to residual flow than is digital subtraction angiography

BACKGROUND AND PURPOSE: For intracranial aneurysms treated with Guglielmi detachable coils, long-term follow-up is mandatory because coil compaction may occur and aneurysms may recur. The purpose of this study was to establish a noninvasive technique to visualize residual flow in coiled aneurysms. METHODS: We designed a 3D time-of-flight (3D-TOF) MR angiography (MRA) technique targeted to depict coiled aneurysms that employed a very short TE (1.54-1.60 ms) and a high spatial resolution (0.3 x 0.3 x 0.3 mm3 with zero-filling) to diminish spin dephasing. To diminish spin saturation, image volume was carefully positioned so that the neck of the targeted aneurysm was within 2 cm of the inflow portion along the stream of blood. Fifty-one MRA images of 39 coiled aneurysms in 39 patients were compared with digital subtraction angiography (DSA) images. DSA and MRA findings were interpolated retrospectively for parent and branch arteries' patency, as well as residual flow in aneurysms. In the latest 11 MR studies, a dark-blood 3D turbo spin-echo sequence was added to MRA to negate the effect high-signal-intensity thrombus. RESULTS: MRA visualized all parent and branch arteries with DSA confirmation. MRA visualized residual flow more frequently (38 studies) than did DSA (25 studies). Residual flow space visualized with MRA was always similar to or larger than that with DSA. The dark-blood sequence completely suppressed intraluminal high signal intensity on MRA images and confirmed that the high signal intensity was not due to thrombus. CONCLUSION: TOF MRA targeted to depict coiled intracranial aneurysms is noninvasive and superior to DSA in visualization of residual flow and, hence, useful for follow-up of coiled aneurysms.     

Magnetic resonance angiography in the management of aneurysmal subarachnoid haemorrhage: a study of 51 cases

We report preliminary experience with the use of magnetic resonance angiography (MRA) in the assessment of intracranial aneurysms. The aims of the study were to confirm that aneurysms could be detected and to assess the quality of the images with a view to early surgery if clinically indicated. We studied 51 patients with recent spontaneous subarachnoid haemorrhage with MRA, using a three-dimensional time-of-flight technique. The results of MRA were subsequently confirmed on intra-arterial digital subtraction angiography (IA-DSA) for anatomical correlation, and were considered satisfactory in 38 patients (74.5 %). In 20 patients early surgical obliteration of their aneurysm was possible on the MRA results without recourse to IA-DSA. A total of 37 aneurysms were identified in 32 patients, while the remaining 6 patients did not have an aneurysm. MRA was misinterpreted in 4 patients (7.9 %), and in 9 other patients (17.6 %) MRA was unsatisfactory due to movement artefacts. Received: 1 September 1994 Accepted: 12 May 1995     

Utility of CT angiography and MR angiography for the follow-up of experimental aneurysms treated with stents or Guglielmi detachable coils

BACKGROUND AND PURPOSE: Previous studies have depicted arterial and aneurysmal anatomy with three-dimensional time-of-flight (3D-TOF) MR angiography before and after treatment with Guglielmi detachable coils (GDCs) and with CT angiography before and after treatment with stents and stent-grafts. We investigated the ability of time-resolved contrast-enhanced 3D MR angiography (3D MR digital subtraction angiography [DSA]) to accurately depict the anatomy of experimental lateral aneurysms before and after treatment with GDCs and a variety of stents or stent-grafts, and compared these findings with 3D-TOF MR angiography without and with contrast enhancement and CT angiography. METHODS: Two nitinol stents, two nitinol-polytetrafluoroethylene (PTFE) stent-grafts, and two stainless steel stents were deployed in three dogs with experimental carotid aneurysms. In a fourth animal, one of three aneurysms was completely occluded with GDCs. The other two aneurysms were loosely packed to ensure persistence of some residual aneurysmal lumen. Cut-film angiography, CT angiography, 3D-TOF MR angiography without and with contrast enhancement, and 3D MR DSA were performed in all dogs before and 3 weeks after treatment. RESULTS: 3D MR DSA was superior to conventional 3D-TOF MR angiography without and with contrast enhancement in accurately depicting experimental lateral aneurysms and superior to CT angiography in depicting aneurysms treated by GDCs. 3D MR DSA and CT angiography were comparable in depicting vessels treated with nitinol stents and stent-grafts, whereas CT angiography was superior for showing vessels treated by stainless steel stents. CONCLUSION: We recommend further development and clinical evaluation of 3D MR DSA for imaging cerebral aneurysms before and after treatment with GDCs. 3D MR DSA or CT angiography may be useful for evaluating vessels containing nitinol stents or nitinol-PTFE stent-grafts, whereas CT angiography should be used for follow-up of vessels treated by stainless steel stents.     

三维动态增强MR血管造影对颅内动脉瘤的诊断价值

目的 评价三维动态增强磁共振血管造影(3D DCE-MRA)在颅内动脉瘤诊断中的价值。方法 对54例高度怀疑有颅内动脉瘤的病人行3D DCE-MRA检查，随后行DSA造影及可行的血管内栓塞治疗。3D DCE-MRA用超快速三维梯度回波序列(3D FISP)(钆喷替酸葡甲胺0．2mmol／kg,1次扫描时间10s)，工作站上三维重建，比较3D DCE-MRA及常规DSA在显示动脉瘤、瘤颈及与载瘤动脉关系上的优劣，及对血管内栓塞治疗的价值。结果 39例脑动脉瘤患者共45个动脉瘤，3D DCE-MRA对动脉瘤的敏感度为96％，特异度73％，准确度90％。3D DCE-MRA对动脉瘤细节及瘤颈的显示明显优于常规DSA，尤其是颈内动脉海绵窦部及椎动脉近小脑后下动脉的动脉瘤，可指导DSA显示动脉瘤方向及预先制定治疗方案。但对周边部及动脉分岔处小动脉瘤的诊断应谨慎。结论3D DCE-MRA能无创有效地诊断颅内动脉瘤，所提供的三维信息对治疗方案的制定具有极大帮助。当诊断有怀疑时，应结合DSA检查。     

脑动脉瘤的MR血管造影与IA—DSA的对照研究

对经手术证实的２０例脑动脉瘤的ＭＲＡ和ＩＡ－ＤＳＡ的影像进行了对照分析研究，经ＭＲＡ检出１９例（９５％）动脉瘤，１０ｍｍ以下的动脉瘤９例，最小的为４ｍｍ，与ＤＳＡ检出率（１９／２０）相仿。ＭＲＡ的定位符合率为８４％，低于ＤＳＡ（９５％）。１３／１９例（６８％）在ＭＲＡ图象上能显示动脉瘤的瘤颈。作者认为ＭＲＡ是一种新的非侵入性的血管影像方法，可作为脑动脉瘤高危病例的筛选检查，随着ＭＲＡ技术的进一步完善，ＭＲＡ有望在神经外科领域替代部分侵入性血管造影检查。     

Modern cross-sectional imaging in the diagnosis and follow-up of intracranial aneurysms

Digital subtraction angiography (DSA) is still considered the gold standard for most applications in neurovascular imaging. However, with the ongoing development of cross-sectional imaging modalities DSA is increasingly being replaced by less invasive methods. This contribution describes the diagnostic value and the increasing potential of computed tomography angiography (CTA) and magnetic resonance angiography (MRA) in the diagnosis and follow-up of intracranial aneurysms. The main role of CTA is in the diagnosis and therapy planning of ruptured aneurysms; in contrast, MRA plays an increasingly important role in the screening for asymptomatic aneurysms (especially in cases of familial subarachnoid hemorrhage) and in the follow-up after endovascular therapy with coils and/or intracranial stents. Technical issues concerning examination technique are covered here as well as an approach to advanced postprocessing of the image data. Furthermore, a brief outlook on the impact of new developments (MRA with parallel imaging and at 3.0 T) is given.     

颅内动脉瘤 3D DCE-MRA与DSA对照研究

目的 探讨三维动态增强MR血管造影(3D DCE-MRA)在颅内动脉瘤诊断中的价值. 资料与方法 对39例临床拟诊动脉瘤和常规MRA可疑动脉瘤的患者行3D DCE-MRA,随后行DSA,比较两种方法 对颅内动脉瘤的显示情况. 结果 34例动脉瘤患者中共有动脉瘤41个,3D DCE-MRA对动脉瘤诊断的敏感性为95%,特异性为80%,准确性为85%,3D DCE-MRA与DSA比较,差异无统计学意义(P>0.05). 结论 3D DCE-MRA是一项无创、安全、简便和可靠的诊断颅内动脉瘤的方法,对于颅内较大血管的动脉瘤的显示,可以取代DSA.