Fusion imaging of 3D MR cisternography/angiography for differential diagnosis of internal carotid-posterior communicating artery aneurysms and infundibular dilations

By using a fusion imaging of three-dimensional (3D) magnetic resonance cisternography (MRC) and coregistered magnetic resonance angiography (MRA), protrusions at the bifurcation of the internal carotid-posterior communication artery, detected by MRA, were investigated to differentiate between the infundibular dilations and aneurysms. The MRA, obtained by the 3D time-of-flight sequence, showed the flow-related arterial structures by means of an inflow effect mainly induced by the peak systolic flow velocity. The MRC, obtained by 3D fast spin-echo sequence, depicted the contours of the vascular structures within the cisternal space in contrast to the surrounding cerebrospinal fluid. Fusion images of 3D MRC/MRA showed the anatomy of protrusions from the different viewpoints with flow-related intraluminal images (MRA) in conjunction with outer-wall configuration images of the vascular structures (MRC). This imaging technique may be useful to differentiate the infundibular dilations from the internal carotid-posterior communicating artery aneurysms.     

The usefulness of 3D MR angiography in surgery for ruptured cerebral aneurysms

BACKGROUND

We have used magnetic resonance angiography (MRA) in screening for unruptured cerebral aneurysms since 1993. The development of high-resolution magnetic resonance (MR) imaging has led to a remarkable improvement in image quality. Three-dimensional (3D) MRA can be used for surgical simulation. Here, we report on the usefulness of and problems associated with 3D MRA for the surgery of ruptured cerebral aneurysms.

METHODS

Between June 1998 and June 2000, 106 patients with SAH diagnosed by 3D MRA underwent surgery. We compared 3D MRA images with operative findings and investigated the usefulness of this assessment tool.

RESULTS

In 48 of 106 cases (45.3%), we were able to perform surgery based on 3D MRA alone. By using the 3D images, we could easily detect the relative location of the aneurysm, its neck and the surrounding arteries. The remaining cases required further examinations because of uncertainty of diagnosis or insufficient information.

CONCLUSION

3D MRA is a safe and useful procedure for the diagnosis and surgery of ruptured cerebral aneurysms. However, in approximately half of all cases, 3D computed tomographic angiography (CTA) or digital subtraction angiography (DSA) is required in addition for the planning of surgery. It is important to use 3D MRA for surgery only after taking sufficient consideration of certain limitations peculiar to MRA.     

零回波时间动脉自旋标记MR血管成像评估颅内动脉瘤

目的 观察零回波时间(ZTE)动脉自旋标记(ASL)MR血管成像(MRA)评估颅内动脉瘤(IA)的价值。方法 对18例临床疑诊IA患者行头颈部时间飞跃法(TOF)MRA(TOF-MRA)及ZTE ASL-MRA,并于之后2天内行头颈部数字减影血管造影(DSA);评价2种MRA图像显示IA质量(优、良、中等或差)及IA定量参数(瘤高、瘤宽及瘤颈),比较其图像质量评分差异;以DSA结果为金标准,采用组内相关系数(ICC)观察3种检查所获IA定量参数的一致性。结果 18例共21个IA纳入研究。ZTE ASL-MRA显示IA图像质量评分[4(4,4)]高于TOF-MRA[4(3,4),Z=－2.40,P=0.02]。ZTE ASL-MRA(ICC=0.99、0.98、0.99)及TOF-MRA(ICC=0.96、0.96、0.93)所示IA瘤高、瘤宽及瘤颈与DSA结果的一致性均强(P均<0.05)。结论 ZTE ASL-MRA可用于无创、定量评估IA。     

Preoperative assessment of microvascular decompression for hemifacial spasm with fusion imaging of 3D MR cisternogram/angiogram

The preoperative assessment of microvascular decompression (MVD) for hemifacial spasm has been performed with MRI, but assessment of the compressive status by 2D imaging has a number of limitations. We used a fusion image of the 3D MR cisternogram and co-registered 3D MR angiogram, reconstructed from MR cisternogram, obtained by 3D fast spin-echo sequence, and MR angiography, 3D time-of-flight and spoiled-gradient recalled sequences, for the preoperative assessment of the offending artery in 10 patients with hemifacial spasm. The anatomical relationship of the nerve-vessel complex was assessed on the simulated images, and compared with the intraoperative findings. The fusion image of the 3D MR cisternogram/angiogram depicted contours of the brain, nerves, and vessels clearly, and that allowed precise assessment of the pathogenic compression of the facial nerve by the offending vessels, comparative to the operative findings. The fusion imaging of the 3D MR cisternogram/angiogram may provide useful information in the surgical planning of MVD for hemifacial spasm.     

Assessment of the signal intensity distribution pattern within the unruptured cerebral aneurysms using color-coded 3D MR angiography

To evaluate the interaction between the MR signal intensity distribution pattern and bleb formation/ deformation of the aneurysmal dome, fifty cases of the unruptured cerebral aneurysms were investigated with the color-coded 3D MR angiography. Patterns were categorized into central-type, neck-type and peripheral-type according to the distribution of MR signals with low-, moderate- and high signal intensity areas. Imaging analysis revealed the significant relationship (P < 0.02) of the peripheral-type aneurysms to the bleb formation and deformation of the dome, compared with those of central- and neck-type. Additionally, peripheral-type signal intensity distribution pattern was shown with aneurysms harboring relatively large dome size and lateral-type growth including internal carotid aneurysms. Prospective analysis of intraaneurysmal flow pattern with the color-coded 3D MR angiography may provide patient-specific analysis of intraaneurysmal flow status in relation to the morphological change of the corresponding aneurysmal dome in the management of unruptured cerebral aneurysms.     

Serial FIB/SEM imaging for quantitative 3D assessment of the osteocyte lacuno-canalicular network

Up to now, a quantitative three-dimensional (3D) assessment of the lacuno-canalicular network (LCN) within bone has not been achieved in a comprehensive way and the LCN has mostly been investigated using two-dimensional imaging methods only. First attempts for the 3D assessment of the osteocytes and their cell processes have been reported using different imaging techniques. Nevertheless, various experimental limitations allowed for assessment of isolated or incompletely interconnected osteocytes only. On the other hand, serial focused ion beam/scanning electron microscopy (FIB/SEM) currently seems to be a promising imaging method for quantitative 3D assessment of the LCN. However, combined 3D visualization and quantification of the LCN using serial FIB/SEM imaging has not been reported so far. The aim of this study was to provide a proof of concept that serial FIB/SEM meets all requirements for quantitative 3D imaging of the LCN. To this end, we developed a new bone sample preparation protocol for serial FIB/SEM imaging providing a resolution on the order of 30nm. This technique was successfully applied to the mid-diaphysis of a mouse femur. Moreover, we devised and applied novel measures for subsequent quantitative 3D morphometry of the LCN. Briefly, serial FIB/SEM was shown to be an appropriate technique to quantify the morphology of the LCN truly in 3D. This will allow investigating bone matrix changes on an ultrastructural level, which result from aging, disease, and treatment.     

Preoperative assessment of hemifacial spasm by the coronal heavily T2-weighted MR cisternography

Background

Microvascular decompression (MVD) has become a well-established surgical procedure for hemifacial spasm (HFS). Before surgery, it is essential to evaluate any possible deformity of the brainstem and establish the precise location of the offending vessels. In the present study of HFS patients we examined coronal sections taken by heavily T2-weighted MR cisternography in addition to routine axial sections, and assessed the usefulness of these images through comparison with intraoperative findings.

Methods

Eighty patients with HFS underwent preoperative coronal heavily T2-weighted MR cisternography before microvascular decompression surgery. Three neurosurgeons examined the preoperative axial and coronal MR images and evaluated vessel invagination into the brainstem. The usefulness of coronal sections was assessed statistically by the Mann-Whitney U test.

Results

Invagination of the offending vessel into the brainstem was observed in 24 cases (30.0%). In 19 patients, it was predicted preoperatively that compression of the flocculus and brainstem would be required in order to approach the offending vessels. Coronal MR cisternography was significantly more useful in cases with vessel invagination into the brainstem than in cases without invagination.

Conclusions

Coronal sections obtained by MR cisternography are able to demonstrate the severity of vessel invagination into the brainstem as well as revealing the presence of the offending vessel. This information is helpful for planning a suitable approach to the root exit zone.     

支架成形术治疗颅内血管狭窄的安全性及短期疗效分析

目的　评价血管内支架成形术治疗颅内动脉狭窄的安全性及短期疗效。方法　对 4 6例患者 5 0处颅内动脉狭窄病变行血管内支架成形术 ,其中基底动脉狭窄 16处 ,椎动脉颅内段狭窄12处 ,颈内动脉颅内段狭窄 13处 ,大脑中动脉狭窄 9处。结果　 5 0处狭窄中有 4 9处成功地进行了支架成形术 (98% ) ,动脉狭窄程度从治疗前的 (72 4± 12 3) %降为 (10 6± 7 8) %。本组患者无手术死亡及缺血性脑卒中 ;4例出现和操作有关的并发症 ,其中 1例发生近端颅外段颈内动脉夹层 ,1例微导丝引起颅内出血 ,2例穿刺部位出现皮下血肿。 37例患者临床随访超过 6个月 (平均 8 5个月 ) ,无缺血性脑卒中发生。结论　血管内支架成形术治疗颅内动脉狭窄的成功率高 ,具有一定的安全性 ,但长期疗效有待于进一步随访     

Transcranial Doppler ultrasound for the assessment of intracranial arterial flow velocity—Part 2. Evaluation of intracranial arterial disease

Transcranial (TC) pulsed Doppler ultrasound was used to evaluate flow velocity within the intracranial basal cerebral arteries in 71 patients with cerebrovascular disease as revealed by arteriography. Abnormalities of the fast-Fourier transformed (FFT) Doppler spectra were used to detect and classify obstructive lesions as well as dilative arteriopathy of the carotid siphon, the middle, anterior, and posterior cerebral arteries, and the basilar artery. Functional stenosis due to large shunting volumes in patients with arteriovenous malformations and in the presence of significant collateralization of extracranial obstructive lesions were similarly diagnosed.     

Transparent imaging of CT angiography for the delineation of cerebral aneurysms]

Transparent imaging with volume rendering of CT angiography (CTA) was used to delineate cerebral aneurysms. Five unruptured cerebral aneurysms discovered incidentally on MR angiography were delineated as transparent CTA images and compared with routine three-dimensional CTA images. Reconstructing the volume data sets by adjusting the opacity level and range of CT values allowed transparent visualization of the aneurysm with its related vessels through the bony structures of the cranial base. Transparent imaging of CTA may be a useful adjunct for the evaluation of an aneurysm adjacent to the bony structure.     

三维动态增强磁共振血管造影用于犬颈动脉支架植入术后随访的可行性

目的分析颈动脉支架在犬三维动态增强磁共振血管造影（3DCE-MRA）图像上的信号及伪影特点,评价3DCE—MRA用于颈动脉支架术后随访的可行性。方法通过外科手术方法在6只犬的颈动脉成功建立非粥样硬化性狭窄,选用3枚镍钛合金自膨式带膜支架及3枚不锈钢（316L）球囊膨胀式支架行经皮血管腔内成形术及颈动脉支架植入术（PTA＋CAs）。于支架植入术后行颈动脉造影及3DCE-MRA。结果PTA＋CAS技术成功率为100％。造影证实2支颈动脉轻度狭窄（〈50％）,1支中度狭窄（≥50o．4且〈700．4）,3支重度狭窄（≥70％）。3DCE-MRA显示镍钛合金支架表现为支架腔边缘呈锯齿样细小的暗带状伪影,伪影引起的腔内假性狭窄约0-30％;不锈钢球囊膨胀式支架表现为支架腔内信号完全丢失。结论3DCE-MRA可用于评价镍钛合金支架腔内是否通畅,尚无法对狭窄程度进行分级;但对于不锈钢球囊膨胀式支架,由于伪影严重,无法评价支架腔内情况。     

Iterative denoising accelerated 3D SPACE FLAIR sequence for brain MR imaging at 3T

PurposeThe purpose of this study was to prospectively evaluate image quality of three-dimensional fluid attenuated inversion recovery (3D-FLAIR) sequence acquired with a high acceleration factor and reconstructed with iterative denoising (ID) for brain magnetic resonance imaging (MRI) at 3-T.Material and methodsPatients with brain tumor who underwent brain MRI were consecutively included. Two 3D-FLAIR sequences were successively performed for each patient. A first conventional FLAIR acquisition (conv-FLAIR) was performed with an acceleration factor of 6. The second acquisition was performed with an increased acceleration factor of 9. Two series one without ID (acc-FLAIR) and one with ID (acc-FLAIR-ID) were reconstructed. Two neuroradiologists independently assessed image quality, deep brain nuclei visualization and white matter/gray matter (WM/GM) differentiation on a 4-point scale.ResultsThirty patients with brain tumor were consecutively included in this study. There were 16 women and 14 men with a mean age of 54 ± 17 (SD) years (range: 22–78 years). Scanning time of Acc-FLAIR-ID and Acc-FLAIR (4 min 40 sec) was 37% shorter than that of conv-FLAIR (2 min 50 sec) (P < 0.01). Improved image quality score was significantly different for both conv-FLAIR and acc-FLAIR-ID compared to acc-FLAIR (P < 0.01 for both). WM/GM differentiation score of conv-FLAIR was not significantly different compared to acc-FLAIR-ID (P = 0.10). Improved WM/GM differentiation score was different for both sequences compared to acc-FLAIR (P = 0.017 and P < 0.001). Deep brain nuclei visualization score was not different between conv-FLAIR and acc-FLAIR-ID (P = 0.71). However, the improved deep brain nuclei visualization score was significantly different for both sequences compared to acc-FLAIR (P < 0.001 for both).ConclusionScanning time of 3D-FLAIR sequence using a high acceleration factor reconstructed with ID algorithm can be reduced by 37% while preserving image quality for brain MRI.     

MSCT血管成像技术对椎动脉狭窄程度评估的比较研究

目的探讨MSCT血管成像技术对椎动脉狭窄程度评估的运用价值。方法对29例临床诊断为后循环缺血,行颈部MSCT椎动脉成像并做了DSA的患者椎动脉资料进行比较研究。所有病例均行MIP等三维成像。结果经MSCT血管成像诊断40支椎动脉狭窄,其中重度狭窄10支,中度8支,轻度22支。DSA共诊断39支椎动脉狭窄,其中重度狭窄10支,中度8支,轻度21支。经与DSA椎动脉造影对比,2种方法在狭窄程度比较上无显著差异(P0.05)。结论MSCT颈椎动脉成像可多方位立体显示颈椎动脉的形态、走形及狭窄情况,经MIP等三维软件处理后,可获得更多的影像诊断信息,MSCT颈椎动脉成像可作为评价椎动脉狭窄的重要手段。     

3.0T MR三维成像序列在腰骶神经根成像上的应用

[目的]探讨MR 3D-FIESTA序列和3D-MERGE序列在腰骶神经根成像上的可行性,比较两者所得神经根影像的优缺点。[方法]对30例正常志愿者和40例考虑腰椎间盘突出神经根受压患者分别行3D-FIESTA序列和3D-MERGE序列冠状位成像。由4名高年资医师对所得图像质量进行可视化评价,并比较两序列所得图像神经根的信噪比和对比噪声比。[结果]两序列在L_1～S_1节前神经根、神经节以及L_3～S_1节后神经根显示上基本一致,在L_1和L_2的节后神经根显示上3D-FIESTA序列不及3D-MERGE序列。尽管3D-FIESTA序列对正常神经根显示评分优于3D-MERGE序列[(3.72±0.28) vs (3.36±0.31),P0.05),前一序列对受压神经根的显示评分不及后一序列[(2.26±0.57) vs (2.81±0.42),P0.05)。对神经根的SNR及神经根与椎体CNR的比较,3D-FIESTA序列为(48.37±9.29)、(33.25±15.46),而3D-MERGE序列分别为(122.19±15.54)、(83.92±20.47),前者不及后者(P0.05)。然而,在神经根与脑脊液的CNR方面, 3D-FIESTA序列显著优于3D-MERGE序列[(230.57±65.02) vs(81.94±20.96),P0.05]。[结论] 3D-FIESTA序列与3D-MERGE序列均可良好显示腰骶神经根:3D-FIESTA序列适合于显示椎管内节前神经根;3D-MERGE序列则可更好的显示侧隐窝段及远端神经根和受压的神经根。