Relative value of sliding-thin-slab multiplanar reformations and sliding-thin-slab maximum intensity projections as reformatting techniques in multisection CT angiography of the cervicocranial vessels

BACKGROUND AND PURPOSE: To investigate image quality and vascular delineation of multisection CT (MSCT) angiography of the cervicocranial vessels with sliding-thin-slab (STS) maximum intensity projections (MIP) and multiplanar reformations (MPR). MATERIALS AND METHODS: Ten patients examined with a standardized protocol on a 16-section MSCT were included in the study. The data were reformatted as MIP and MPR in 3 planes for each subject; both reformatting techniques were applied in an STS technique with an increment of 3 mm. Images were evaluated independently by 3 blinded readers grading image quality parameters and vascular delineation of supra-aortic arteries and veins. An extension of the Mantel-Haenzel row mean score test was used to compare the distribution of scores for vascular delineation and image quality between STS MIP and STS MPR. RESULTS: STS MIP reformations were significantly superior to STS MPR in the delineation of all extra- and intracranial arteries and arterial segments and in the delineation of the cavernous sinus and the internal cerebral veins (P < .05). No significant differences were found for the large venous vessels, the visual assessment of vascular contrast, or the impact of imaging artifacts. CONCLUSION: Because STS MIP reformations were preferred to or equal to STS MPR in all aspects, we recommend STS MIP as the primary reformatting technique in MSCT angiography of the cervicocranial vessels in addition to viewing the source images.     

Evaluation of the hepatic artery in potential donors for living donor liver transplantation by computed tomography angiography using multidetector-row computed tomography: comparison of volume rendering and maximum intensity projection techniques

PURPOSE: To compare the volume rendering (VR) and maximum intensity projection (MIP) computed tomography angiography (CTA) techniques using multidetector-row CT for hepatic artery evaluation of potential donors for living donor liver transplantation (LDLT). METHOD: Over a 9-month period, CTA using multidetector-row CT and conventional angiography was performed in 62 consecutive potential donors for LDLT. Acquisition of arterial phase scans was initiated within 5 seconds after reaching enhancement of the descending aorta up to 70 HU as measured by a bolus-tracking technique (collimation = 1.25 mm, table speed = 7.5 mm, reconstruction interval = 0.625 mm). Postprocessing was performed on a commercially available workstation. Computed tomography angiography images of the hepatic artery were made using the VR and MIP techniques. A total of 10 to 30 images of various planes were generated to reveal the origins and branching patterns of hepatic arteries. With a 2-week interval, two reviewers separately evaluated CTA using VR and MIP techniques, specifically evaluating anatomic variations and hepatic arterial conspicuity. The results of conventional angiography were considered to represent the gold standard. The difference in postprocessing time between the two techniques was statistically analyzed by the Student t test, and the differences in arterial conspicuity and in the identified number of the hepatic artery to segment IV of the liver were analyzed by the chi2 test. RESULTS: Two CT examinations (3%) were technically inadequate for generating CTA because of respiratory motion artifact. The average times for postprocessing of VR and MIP images were 8.1 +/- 3.8 minutes and 5.0 +/- 0.7 minutes, respectively. Variations of hepatic arterial anatomy were present in 19 patients (32%) on conventional angiography. In 8 patients (13%), there was discrepancy in the variations of hepatic arterial anatomy between the two techniques: MIP was correct in 7 patients, and VR was correct in 1 patient. The dominant artery supplying segment IV was identified in 51 patients (85%) with MIP and in 39 patients (65%) with VR. There was no significant difference in conspicuity of the hepatic arteries using either the MIP or VR technique. CONCLUSION: In CTA techniques using multidetector-row CT, MIP is superior to VR for the hepatic arterial evaluation of potential LDLT donors in terms of depicting anatomic variations and postprocessing time.     

Comparative assessment of helical CT-angiography, 2D TOF MR-angiography and 3D gadolinium enhanced MRA in aorto-iliac occlusive disease

PURPOSE: To compare helical CT-angiography (CTA) and two techniques of MR angiography (MRA) to conventional angiography in aorto-iliac occlusive disease. MATERIALS AND METHODS: The abdominal aorta and iliac arteries in 22 patients (4 for preoperative assessment of abdominal aortic aneurysm and 18 for peripheral vascular disease) were imaged using four techniques: digital subtraction angiography ("gold standard"), 2D TOF MR angiography, 3D Gd-enhanced MR angiography and helical CT angiography. Source (CTA and 2D TOF MRA) and MIPed images (after subtraction measures before and after gadolinium injection for 3D Gd-MRA) were reviewed. RESULTS: Sensitivity, specificity and accuracy for the detection of significant (>50%) stenosis and occlusion of aorto-iliac arteries were respectively: 38%, 89%, 77% for 2D TOF MRA; 75%, 71%, 72% for 3D Gd-MRA and 95%, 90%, 92% for CTA. Excluding the internal iliac arteries, results were 54%, 96%, 88% for 2D TOF MRA; 96%, 80%, 83% for 3D Gd-MRA and 92%, 93%, 95% for CTA. CONCLUSION: 3D Gd-MRA, a technique with potential for further improvement, is superior to 2D TOF MRA for detecting significant stenosis and occlusion of aorto-iliac arteries. Results at Gd-MRA are nearly similar to those at CTA (after excluding internal iliac arteries). Results at Gd-MRA are not affected by calcified plaque.     

Subtracted 3D CT angiography for evaluation of internal carotid artery aneurysms: comparison with conventional digital subtraction angiography

BACKGROUND AND PURPOSE: 3D computed tomographic angiography (3DCTA) has been used recently for the evaluation of intracerebral aneurysms, but it is difficult to use this technique to visualize aneurysms near the base of the skull because of the presence of bone. Subtracted 3DCTA could replace digital subtraction angiography (DSA) for evaluation of aneurysms near the base of the skull if the 2 methods were to give similar results. The aim of this study was to compare the evaluation of aneurysms of the internal carotid artery (ICA) near the base of the skull by subtracted 3DCTA and DSA. METHODS: CTA and DSA were obtained in 25 patients with unruptured aneurysms of the ICA. To create subtracted 3DCTA images, we used a volume subtraction (VS) method, wherein nonenhanced volume data are subtracted from enhanced volume data. CTA and DSA were reviewed by 2 neuroradiologists who performed the detection and characterization of aneurysms of the ICA by using 2D multiplanar reformatted (MPR) and VS- and nonsubtracted (NS)-3DCTA images with volume rendering techniques. RESULTS: DSA detected 29 aneurysms in the 25 patients. VS-3DCTA detected all 29 aneurysms in the 25 patients and was equivalent to DSA for evaluating their characteristics (location, size, and direction). NS-3DCTA detected 19 (1 cavernous, 4 ophthalmic, 1 superior hypophyseal, 7 posterior communicating, and 6 anterior choroidal artery) of these 29 aneurysms, but it could not characterize ophthalmic and superior hypophyseal artery aneurysms because they were only partly visible on NS-3DCTA because of bony structures. 2D-MPR images detected all but the small aneurysms (24 of 29 detected). VS-3DCTA and 2D-MPR could visualize all branching arteries (ophthalmic, posterior communicating, and anterior choroidal) detected by DSA, but NS-3DCTA could not visualize ophthalmic arteries because of the presence of bony structures. CONCLUSION: VS-3DCTA can be used as an alternative to DSA for preoperative examination of aneurysms near the skull base, where it provides equivalent identification and characterization.     

Comparison of contrast-enhanced ct angiography and gadolinium-enhanced MR angiography in the detection of subsegmental-sized pulmonary embolism. An experimental study in a pig model

Purpose: 
To compare contrast-enhanced CT angiography (CTA) and gadolinium-enhanced MR angiography (MRA) for the detection of subsegmental-sized pulmonary emboli in a pig model. Material and Methods: 
In 5 anesthetized pigs, 3-mm diameter embolic materials made of Konjac, a semisolid food, were introduced through the internal jugular vein into pulmonary arteries. After embolization, CTA and MRA images were obtained. Respiration was suspended during CTA and MRA image acquisition. Two readers reviewed the CTA and MRA images to detect emboli. The pigs were sacrificed, and sliced specimens of inflated lung served as the gold standard. Results: 
Thirty-six emboli were detected within peripheral arteries. The sensitivity (and 95% confidence intervals) of CTA for the two readers were 57% (39-74%) and 66% (48-81%), and 88% (69-98%) and 92% (74-94%) for MRA. The specificity of CTA was 95% (91-97%) and 98% (96-99%), and that of MRA was 85% (74-93%) and 90% (80-96%). Interobserver agreement was higher for MRA (kappa 0.898) than CTA (kappa 0.574). Conclusion: 
For the detection of subsegmental pulmonary emboli, MRA was superior to CTA, with a higher sensitivity and interobserver agreement by demonstrating perfusion deficits.     

Assessment of the cerebellar arteries with multidetector computed tomography angiography benefits from submillimeter slice thickness

Purpose

To evaluate the accuracy of 64-row-multidetector computed tomography (MDCT) with different slice thickness (0.625 vs. 1.25 mm) in assessing the cerebellar arteries.

Materials and methods

A total of 21 consecutive patients who underwent computed tomography angiography (CTA) of the cervicocranial arteries (64-row MDCT; slice thickness, 0.625 mm) because of suspicion of cerebral ischemia were enrolled retrospectively. The MDCT data set was secondarily reconstructed to a slice thickness of 1.25 mm. The examinations were reviewed by three independent blinded observers. Recorded parameters for reconstructed slice thicknesses of 0.625 compared to 1.25 mm were visualization and edge enhancement (based on a developed phantom reference model) of the cerebellar arteries including anterior and posterior inferior cerebellar arteries and the superior cerebellar artery.

Results

With 0.625-mm slices, significantly more vessel segments were visualized and edge enhancement was superior compared to 1.25-mm slices by the three readers, and a significant difference for the interaction between vessel segments and the slice thickness was found (P<.001). Furthermore, for a slice thickness of 1.25 mm, there was a significant difference in visualization (P=.0042) and edge enhancement (P=.0015) of vessel segments between the three readers, whereas for thinner slices (0.625 mm), no significant differences were found (P=.412, P=.465).

Conclusions

MDCT with slice thickness of 0.625 mm is superior to 1.25 mm reconstructed slice thickness regarding the visualization of cerebellar arteries, representative for smallest assessable arteries in CTA. This is paralleled by a sharper edge enhancement of the vessel contours resulting from a reduced partial volume effect. Conclusively, cranial CTA protocols should be routinely optimized to generate submillimeter slices for diagnostic purposes and digital storage as additional diagnostic value can be expected.     

Usefulness of preoperative three-dimensional volumetric analysis of carotid body tumors

Purpose

The Shamblin classification is the commonest method to predict complications and outcomes during carotid body tumor (CBT) resection. The aim of this study is to describe the utility of the three-dimensional volumetric reconstruction (3DVR) analysis of the CBT and its relationship with postoperative outcomes.

Methods

Preoperative computed tomography angiography (CTA) was obtained to perform 3DVR of the CBT. Imaging data were analyzed and correlated with surgical outcomes: estimated blood loss (EBL), surgical time (ST), and hospital length of stay (HLOS). The Pearson test was used to determine the correlation between volume and postoperative outcomes.

Results

Fifty-seven patients were studied, 13 had Shamblin type I tumors with a mean 3DVR of 7.69 cm³ (standard deviation [SD 8.27]), 21 were type II with a mean 3DVR of 15.57 cm³ (SD 8.40), and 23 were type III with a mean 3DVR of 30.58 cm³ (SD 20.16). EBL mean was 559 milliliters (mL) (standard error [SE] 80.44), the mean ST of resection was 202 min (SD 67), and the mean HLOS was 5.8 days (SD 3.23). The Pearson test showed a correlation of r?=?0.69 (p?<?0.0001) between 3DVR and EBL, a r?=?0.4 (p?=?0.05) was obtained between 3DVR and ST, and finally, a r?=?0.3 (p?=?0.05) between 3DVR and HLOS was obtained.

Conclusion

The preoperative 3DVR determination of CBTs allows to analyze possible predictors of surgical outcomes. We found a positive correlation between the 3DVR volume and EBL. Further research is necessary to validate this method in the evaluation of these rare neoplasms.

     

64层CT增强扫描对胃癌患者胃供血动脉的显示

目的 探讨64层CT增强扫描对胃癌患者胃供血动脉的显示及血管变异的检出情况.方法 回顾性分析行CT检查的连续66例胃癌患者资料.CT扫描根据目标血管管径及跨层走行情况,凋节滑块间距得到胃供血动脉薄层滑块最大密度投影图像(STS-MIP),4周后利用血管追踪生长技术获得同一组病例的三维容积重组图像(AVVR).分析胃的直接和间接供血动脉显示率及来源.采用McNemar检验(精确概率法)比较STS-MIP、AVVR对胃供血动脉的显示率,采用独立样本t检验比较AVVR重组上胃供血动脉显示与动脉强化CT值的关系,分析血管分支变异情况.结果 AVVR及STS-MIP对胃间接供血动脉的显示率均达到100%(66/66).对胃左动脉(LGA)和胃网膜右动脉(RGEA)的显示率分别为98.5%(65/66)、100.0%(66/66)及97.0%(64/66)、100.0%(66/66);AVVR对胃右动脉(RGA)、胃网膜左动脉(LGEA)、胃短动脉(SGA)及胃后动脉(PGA)的显示率分别为68.2%(45/66)、53.0%(35/66)、7.6%(5/66)和18.2%(12/66),低于 STS-MIP的显示率,分别为98.5%(65/66)、97.0%(64/66)、59.1%(39/66)和63.6%(42/66),差异有统计学意义(P<0.01).采用AVVR重组方法,显示的LGEA、RGEA及SGA分别为35、64和5支,腹腔干强化CT值分别为(272±44)、(256±44)和(298±39)HU,未显示的上述血管支数分别为31、2、61支,腹腔干强化CT值分别为(229±42)、(141±26)和(249±47)HU,差异有统计学意义(t值分别为4.043、3.641和2.278,P值均<0.05).检出迷走肝左动脉13例(发生率19.7%),腹腔干大血管分支变异7例(变异率10.6%).结论 64层CT可清晰显示胃周供血动脉及其相关变异,为胃癌术前方案的制定提供参考.     

一键去骨法与减影法在头颅CTA血管重建中的对照研究

目的:比较一键去骨法与减影法在头颅CTA血管重建中图像质量及对血管病变检出的差异,探讨一键去骨法的应用价值。方法:对247例患者分别进行一键去骨法和减影法头颅CTA重建,对两种去骨法CTA所得颈内动脉(七段),大脑前、中、后动脉(分别为四段),椎动脉(四段),前后交通动脉和基底动脉血管图像质量按照5个等级标准进行评分,同时分别记录两组图像诊断病变血管数目分布差异。应用秩和检验比较两组血管图像质量差异,配对卡方检验比较两者诊断病变血管能力差异。结果:247例病例共10868段脑动脉。两种方法总体图像质量评分无统计学差异(P=0.405),一键去骨法血管质量评分均值为4.49±1.098,减影法血管质量评分均值为4.50±1.065,双侧椎动脉V4段图像质量减影法优于一键去骨法(左侧V4:P=0.026,右侧V4:P=0.017)。双侧颈内动脉C2段图像质量一键去骨法优于减影法(左侧C2:P=0.039;右侧C2:P=0.028)。其他分段血管图像质量评分两者无统计学差异。在血管狭窄、闭塞及动脉瘤检出方面两者无统计学差异。在血管钙化及血管病变术后金属夹、支架显示一键去骨法优于减影法(P均为0.000)。结论:一键去骨法对于血管病变显示和图像质量均不劣于减影法,在显示血管钙化和金属夹、支架方面有一定优势,值得应用和推广。     

多层螺旋CT及重建技术在胸部创伤中的临床应用

目的:讨论多层螺旋CT(MSCT)扫描及重建技术在胸部创伤中的临床应用价值。方法:57例胸部创伤病人行MSCT扫描,重建层厚2.5 mm,间隔1.25 mm,将数据传至专门工作站,对骨性胸廓进行多平面重建(MPR)、薄层最大密度投影(STS-MIP)及容积再现(VR)重建,对横断面图像及重建图像进行回顾性分析。结果:57例胸部创伤患者中,发现肺挫伤44例,肺撕裂伤4例,肺不张及肺萎缩11例,气胸27例,胸腔积液42例,肋骨骨折36例,肋软骨骨折2例,肩胛骨骨折6例,锁骨骨折3例,胸椎骨折1例。MPR图像可清楚显示骨折线的走行及移位,3D重建图像从各个方位显示了骨折的空间改变。结论:多层螺旋CT扫描能够清晰显示肺部损伤情况,胸廓重建图像可以显示骨折的立体空间改变,两者相结合,对临床制定治疗方案具有重要的参考价值。     

Spiral computed tomographic angiography of the renal arteries: A prospective comparison with intravenous and intraarterial digital subtraction angiography

Purpose: To assess the accuracy of computed tomographic angiography (CTA) in the evaluation of the renal arteries in comparison with intravenous (IVDSA) and intraarterial digital subtraction angiography (IADSA). Methods: In 18 patients, 35 CTAs and DSAs (27 IADSA, 8 IVDSA) of the renal arteries were performed. CTA was done with 2–3 mm collimation, 2–4 mm/sec table speed, after intravenous injection of 80 ml of contrast medium at 4 ml/sec with a scanning delay time of 14–21 sec. No previous circulation time curve was performed. CTA data were reconstructed with maximum intensity projection (MIP) and shaded surface display (SSD). The presence of stenosis was assessed on a three-point rating scale (grade 1–3). The quality of the examinations; visualization of the ostium, the main artery, and its branches; vessel sharpness, linearity, and intraluminal contrast filling were evaluated. We compared CTA with DSA. Results: CTA had 96% sensitivity, 77% specificity, and 89% accuracy in the detection of stenoses > 50%. Due to technical errors two stenoses were erroneously diagnosed as positive but there were no false negative diagnoses. The quality of CTA was good in 56% and moderate in 34% of cases. Visualization of the ostium and main artery was graded as 1.74 (out of 2) points and of the renal branches as 1.02 (out of 2) points. The quality of CTA images was worse than that of IADSA in 52%, equal in 41%, and better in 7% of cases. CTA was equal to IVDSA in 25% and better in 75% of the cases. Conclusion: CTA is an accurate noninvasive method for the evaluation of renal arteries. Examination quality is essential for the diagnosis. CTA is limited in its ability to visualize the branches of the renal artery and accessory arteries. CTA seems to be superior to IVDSA.     

胰腺供血动脉的16层CT血管成像对比研究

目的 探讨16层CT血管成像3种重组技术：最大密度投影（MIP）、薄层最大密度投影（TSMIP）和容积重组（VR）对胰腺供血动脉的显示率，比较显示胰腺供血动脉的优势。方法 40例非胰腺病变的患者行腹部16层CT增强扫描和动脉期血管成像。统计TSMIP、MIP及VR对胰腺直接、间接供血动脉的显示率及显示状况。用配对X^2。检验观察显示率的差异；用配对秩和检验观察显示状况的差异。结果 （1）3种重组技术对胰腺间接供血动脉的显示率均为100％（40／40）。TSMIP、MIP、VR对胰十二指肠上后动脉（PSPDA）的显示率分别为92．5％（37／40）、77．5％（31／40）、67．5％（27／40）；对胰十二指肠上前动脉（ASPDA）的显示率分别为95．0％（38／40）、82．5％（33／40）、75．0％（30／40）；对胰十二指肠下动脉（IPDA）的显示率分别为92．5％（37／40）、75．0％（30／40）、57．5％（23／40）。（2）TSMIP与VR对ASPDA、PSPDA、IPDA的显示率的差异有统计学意义（X^2值分别为6．27、7．81、13．07、P值均〈0．01）；TSMIP与MIP对IPDA的显示率差异有统计学意义（X^2值为4．50，P〈0．05）。（3）TSMIP与MIP对胃十二指肠动脉（Z=-3．317，P=0．001）、胃左动脉（Z=-3．557，P=0．000）、肝固有动脉（Z=-2．810，P：0．005）、ASPDA（Z=-4．796，P=0．000）、PSPDA（Z=-4．400，P=0．000）和IPDA（z=-4．811，P=0．000）的显示状况的差异有统计学意义：TSMIP与VR对胃十二指肠动脉（Z=-3．162，P=0．003）、胃左动脉（Z=-3．051，P=0．002）、肝固有动脉（Z=-2．460，P=0．014）、ASPDA（Z=-5．166，P=0．000）、PSPDA（Z=-5．056．P=0．000）和IPDA（Z=-5．564，P=0．000）的显示状况的差异有统计学意义；MIP与VR对ASPDA（Z=-3．000，P=0．002）、PSPDA（Z=-2．352，P=0．019）和IPDA（Z=-3．500，P=0．000）显示状况的差异有统计学意义。结论 TSMIP显示胃左动脉、肝固有动脉、胃十二指肠动脉和胰腺直接供血动脉优于MIP及VR。MIP显示胰腺直接供血动脉优于VR。     

Preliminary experience with dynamic MR projection angiography in the evaluation of cervicocranial steno-occlusive disease

The application of a contrast-enhanced, two-dimensional MR technique, which provides dynamic projection angiograms at a subsecond temporal frame rate for depiction of the cervical and intracranial arteries, was evaluated in three healthy volunteers and seven patients with various cervicocranial steno-occlusive diseases. Intra-arterial digital subtraction angiography (DSA) served as standard of reference for findings in the patients. Magnetic resonance projection angiography (MRPA) was performed on a standard 1.5-T clinical MR imaging system at intravenous injection of a single dose of contrast agent (0.1 mmol/kg GdDTPA-BMA). Sixty consecutive images of the cerebral circulation were acquired at a temporal frame rate of 900 ms per image in the coronal plane. The collateral flow and the perfusion of the compromised vessel territory were readily assessed by MPRA in patients with occlusion of the internal cerebral artery (ICA) or middle cerebral artery (MCA). The leptomeningeal collateralisation of these patients was displayed in a dynamic fashion. Furthermore, quantitative perfusion measurement provided a difference between both MCA territories in the time to peak (ΔDTTP) of the contrast bolus of 1.12 ± 0.28 s in five patients with severe stenosis or occlusion of the ICA (healthy volunteers 0.19 ± 0.05 s). However, important pathological findings, such as the evaluation of carotid artery stenoses and the intracranial collateral flow pattern in patients with severe carotid stenoses, were not sufficiently assessable as compared with DSA. We conclude that the possibility of obtaining simultaneously information about morphology and perfusion dynamics of the cervicocranial vessels is unique in MPRA as compared with other MR techniques. However, in the applied form, the technique is not a reliable tool for the complete evaluation of the cervicocranial vessels in patients with steno-occlusive disease. Received: 27 January 2000/Revised: 11 July 2000/Accepted: 13 July 2000     

Bone-subtraction CT angiography: evaluation of two different fully automated image-registration procedures for interscan motion compensation

BACKGROUND AND PURPOSE: Bone-subtraction techniques have been shown to enhance CT angiography (CTA) interpretation, but motion can lead to incomplete bone removal. The aim of this study was to evaluate 2 novel registration techniques to compensate for patient motion. MATERIALS AND METHODS: Fifty-four patients underwent bone-subtraction CTA (BSCTA) for the evaluation of the neck vessels with 64-section CT. We tested 3 different registration procedures: pure rigid registration (BSCTA), slab-based registration (SB-BSCTA), and a partially rigid registration (PR-BSCTA) approach. Subtraction quality for the assessment of different vascular segments was evaluated by 2 examiners in a blinded fashion. The Cohen kappa test was applied for interobserver variability, and the Wilcoxon signed rank test, for differences between the procedures. Motion between the corresponding datasets was measured and plotted against image-quality scores. RESULTS: Algorithms with motion compensation revealed higher image-quality scores (SB-BSCTA, mean 4.31; PR-BSCTA, mean 4.43) than pure rigid registration (BSCTA, mean 3.88). PR-BSCTA was rated superior to SB-BSCTA for the evaluation of the cervical internal and external carotid arteries (P<.001), whereas there was no significant difference for the other vessels (P=.157-.655). Both algorithms were clearly superior to pure rigid registration for all vessels except the basilar and ophthalmic artery. Interobserver agreement was high (kappa=0.46-0.98). CONCLUSION: Bone-subtraction algorithms with motion compensation provided higher image-quality scores than pure rigid registration methods, especially in cases with complex motion. PR-BSCTA was rated superior to SB-BSCTA in the visualization of the internal and external carotid arteries.     

螺旋CT肾动脉成像与数字减影血管造影的对比分析

目的:客观评价螺旋CT肾动脉成像的临床应用价值.材料和方法:从本院螺旋CT肾动脉成像(CTRA)资料中选取31例曾做过DSA肾动脉造影(含动脉成形和支架放置术)者,CTRA和DSA图像分别先由两位医师独立观察.分析内容包括解剖变异、有无狭窄及进行狭窄程度分级.最后将结果进行对比分析.结果:CTRA发现狭窄血管33支,其中31支经DSA证实(2支假阳性).符合率为94%.清楚显示5支副肾动脉(经DSA证实).结论:CTRA是肾性高血压筛选的可靠方法并可取代DSA作为首选检查方法.     

颈部CTA图像后处理的临床应用

目的:比较颈部CTA图像后处理方法的优缺点。方法:25例病人,经四排螺旋CT扫描后得到50支颈动脉和椎动脉,分别用3mm、5mm和15mm薄层MIP和SSD方法进行重建。结果:1侧椎动脉闭塞,1侧椎动脉全程较细,32支颈总动脉或颈内、外动脉有斑块,1支颈动脉2级狭窄、11支颈动脉1级狭窄。结论:颈部CTA可以准确地评估颈部动脉粥样硬化,层厚为15mm的薄层MIP可以几乎显示颈总动脉及其分支的全程,显示椎动脉需用3mm的薄层MIP,SSD不能鉴别钙化斑块和增强后的动脉,评估颈动脉需结合重建后的图像和原始的轴位图像。     

First results of computerised tomographic angiography using electron beam tomography

The aim of this study was to evaluate the suitability of electron beam tomography (EBT) with fast continuous volume scanning for CT angiography (CTA) in chest and abdomen. An Evolution XP EBT scanner with a new software version (12.34) was used. One hundred forty images per study can be acquired in 17 s using 3-mm collimation and overlapping image reconstruction. Study protocols for five different clinical applications of EBT CTA were established and evaluated. The EBT CTA technique was performed in 155 patients. High- and homogeneous density values were achieved along the whole course of the vessels; the mean density in the aorta was > 240 HU. Coeliac axis, superior and inferior mesenteric artery, renal and lumbar arteries were visualised in all cases. Maximum intensity projection and shaded surface display reconstruction demonstrated the relation between aneurysm and aortic branches very well due to an excellent resolution along the z-axis. In large scan volumes overlapping image reconstruction demonstrated better resolution along the z-axis than is available with helical CT. The EBT CTA technique proved to be very well suited excellent suitability for evaluation of pulmonary vessels. Compared with helical CT, EBT CTA offers a shorter scan time, which allows higher contrast enhancement in pulmonary vessels. The identification of intraluminal emboli and mural thrombi has improved. The EBT CTA technique is a very reliable tool for evaluation of aortic disease and pulmonary vessels. Received: 17 June 1998; Revision received: 9 September 1998; Accepted: 29 September 1998     

颅脑创伤血管痉挛的CT血管造影评价

目的 :探讨CT血管造影 (CTA)在评价颅脑外伤性血管痉挛中的应用。材料和方法 :对 19例颅脑外伤患者和 10例对照组患者采用多层螺旋CT增强扫描获得原始图像 ,用最大强度投影 (MIP)和容积显示 (VR)技术进行三维重建CTA观察和分析。结果 :所有患者均成功获得良好的CTA图像 ,9例患者发现脑血管痉挛 16处 ,其中 13处出现在大脑中动脉 ,并大多呈串珠样改变。VR显示血管改变最佳 ,可充分显示血管痉挛 ;结合横断面图像可全面评价脑创伤情况。结论 :外伤后脑血管痉挛大多呈串珠样改变 ,CTA VR可充分显示血管痉挛 ,有助于研究外伤后脑血管的变化。     

CT in vascular pathologies

Since the introduction of helical scanners, CT angiography (CTA) has achieved an essential role in many vascular applications that were previously managed with conventional angiography. The performance of CTA is based on the accurate selection of collimation width, pitch, reconstruction spacing and scan delay, which must be modulated on the basis of the clinical issue. However, the major improvement of CT has been provided by the recent implementation of many post-processing techniques, such as multiplanar reformatting, shaded surface display, maximum intensity projections, 3D perspectives of surface and volume rendering, which simulate virtual intravascular endoscopy. The integration of the potentialities of the scanner and of the image processing techniques permitted improvement of: (a) the evaluation of aneurysms, dissection and vascular anomalies involving the thoracic aorta; (b) carotid artery stenosis; (c) aneurysms of abdominal aorta; (d) renal artery stenosis; (e) follow-up of renal artery stenting; and (f) acute or chronic pulmonary embolism. Our experience has shown that the assessment of arterial pathologies with CTA requires the integration of 3D post-processing techniques in most applications. Received 23 December 1997; Accepted 2 January 1998     

3 T contrast-enhanced magnetic resonance angiography for evaluation of the intracranial arteries: comparison with time-of-flight magnetic resonance angiography and multislice computed tomography angiography

PURPOSE: We sought to prospectively evaluate the image quality and visualization of the intracranial arteries using high spatial resolution contrast-enhanced magnetic resonance angiography (CE-MRA) at 3 T and to perform intraindividual comparison with time-of-flight (TOF) MRA and multislice CT angiography (CTA). MATERIALS AND METHODS: Twelve patients (5 men, 7 women, 37-71 years of age) with suspected cerebrovascular disease prospectively underwent MRA and CTA. MRA was performed on a 3 T MR system, including both 3-dimensional (3D) TOF (Voxel dimension: 0.6 x 0.5 x 0.9 mm in 5 minutes and 40 seconds) and 3D CE-MRA (voxel dimension: 0.7 x 0.7 x 0.8 mm in 20 seconds, using parallel acquisition with an acceleration factor of 4). CTA images were acquired on a 16-slice CT scanner (voxel dimension: 0.35 x 0.35 x 0.8 mm in 17 seconds). The image quality and visualization of up to 26 intracranial arterial segments in each study was evaluated by 2 experienced radiologists. The arterial diameter for selective intracranial arteries was measured independently on each of the 3 studies, and statistical analysis and comparative correlation was performed. RESULTS: A total of 312 arterial segments were examined by CE-MRA, TOF-MRA, and CTA. The majority of intracranial arteries (87%) were visualized with diagnostic image quality on CE-MRA with a significant correlation to TOF (R values = 0.84; 95% confidence interval 0.79-0.86, P < 0.0001), and to CTA (R values = 0.74; 95% confidence interavl 0.68-0.78, P < 0.001). The image quality for small intracranial arteries, including the anterior-inferior cerebellar artery, the posterior communicating artery, and the M3 branch of the middle cerebral artery, was significantly lower on CE-MRA compared with TOF and CTA (P < 0.03). There was a significant correlation for the dimensional measurements of arterial diameters at CE-MRA with TOF (r = 0.88, 95% confidence interval 0.81-0.93), and CTA (r = 0.83, 95% confidence interval 0.73-0.90). CONCLUSION: The described 3 T CE-MRA protocol, spanning from the cervical to the intracranial vessels, visualized and characterized the majority of intracranial arteries with image quality comparable with that obtained using TOF-MRA and CTA. Further clinical studies are required to establish the accuracy of the technique in a broader clinical setting.