Comparison of multidetector CT angiography and MR imaging of cervical artery dissection

BACKGROUND AND PURPOSE: Conventional angiography has been historically considered the gold standard for the diagnosis of cervical artery dissection, but MR imaging/MR angiography (MRA) and CT/CT angiography (CTA) are commonly used noninvasive alternatives. The goal of this study was to compare the ability of multidetector CT/CTA and MR imaging/MRA to detect common imaging findings of dissection.MATERIALS AND METHODS: Patients in the data base of our Stroke Center between 2003 and 2007 with dissections who had CT/CTA and MR imaging/MRA on initial work-up were reviewed retrospectively. Two neuroradiologists evaluated the images for associated findings of dissection, including acute ischemic stroke, luminal narrowing, vessel irregularity, wall thickening/hematoma, pseudoaneurysm, and intimal flap. The readers also subjectively rated each vessel on the basis of whether the imaging findings were more clearly displayed with CT/CTA or MR imaging/MRA or were equally apparent.RESULTS: Eighteen patients with 25 dissected vessels (15 internal carotid arteries [ICA] and 10 vertebral arteries [VA]) met the inclusion criteria. CT/CTA identified more intimal flaps, pseudoaneurysms, and high-grade stenoses than MR imaging/MRA. CT/CTA was preferred for diagnosis in 13 vessels (5 ICA, 8 VA), whereas MR imaging/MRA was preferred in 1 vessel (ICA). The 2 techniques were deemed equal in the remaining 11 vessels (9 ICA, 2 VA). A significant preference for CT/CTA was noted for VA dissections (P < .05), but not for ICA dissections.CONCLUSION: Multidetector CT/CTA visualized more features of cervical artery dissection than MR imaging/MRA. CT/CTA was subjectively favored for vertebral dissection, whereas there was no technique preference for ICA dissection. In many cases, MR imaging/MRA provided complementary or confirmatory information, particularly given its better depiction of ischemic complications.

Dissection of the extracranial arteries accounts for 10%–25% of strokes in young and middle-aged patients.¹ It may be spontaneous or traumatic and can cause a variety of clinical presentations, including stroke, headache, neck pain, tinnitus, Horner syndrome, and cranial neuropathies.^1-4 Dissections are typically diagnosed on the basis of a combination of the clinical presentation, imaging studies (conventional angiography, CT/CT angiography [CTA], MR imaging/MR angiography [MRA], and sonography), and exclusion of other arterial disease, particularly atherosclerosis.^1,2,5 In patients with mild or atypical symptoms, noninvasive imaging may facilitate earlier diagnosis and prevent embolic ischemic complications with the use of antithrombotic therapy.^3,6Conventional angiography has historically been considered the gold standard for dissection diagnosis, but it has limitations, which include its cost and invasiveness.^1,7,8 Although the angiographic appearance of dissection is often characteristic, it does not assess the vessel wall for intramural hematoma; because of this feature, dissections in unusual locations or with atypical morphology may be misclassified or attributed to other processes. MR imaging/MRA and CT/CTA have emerged as viable alternatives for both diagnosis and follow-up of dissection.^9-15 In general, the 2 techniques have different strengths and weaknesses. Diffusion-weighted MR imaging is a powerful technique for detecting acute stroke,¹⁶ which may then lead to increased scrutiny of the upstream arterial tree. Axial T1-weighted fat-suppressed images can detect the methemoglobin of the intramural hematoma within the false lumen, a finding referred to as a crescent sign.^9,13 Multidetector CT/CTA has enabled routine acquisition of thinner sections with rapid imaging times, facilitating multiplanar and volume reconstructions. Additionally, it is more widely available (especially at night), has fewer contraindications, and provides greater spatial resolution than MR imaging/MRA. However, the use of ionizing radiation in the relatively young population of patients with dissection is potentially concerning, especially given the often frequent follow-up studies in these patients.Only 1 study to date has compared CT/CTA with MR imaging/MRA for evaluation of dissection, retrospectively reviewing 7 internal carotid dissections and showing CTA to be marginally more effective in the identification of the dissected vessel.¹¹ To our knowledge, this current study is the largest comparative series of cervical artery dissection imaged with both tomographic techniques. Given the higher spatial resolution of CT/CTA, we hypothesized that CT/CTA may be particularly suited to visualize dissections within the smaller vertebral arteries. Additionally, we hypothesized that in a series of known dissections, CT/CTA would be more sensitive to identify specific imaging features associated with dissections.     

Coronary CT angiography for acute chest pain in the emergency department

Acute chest pain in the emergency department (ED) is a common and costly public health challenge. The traditional strategy of evaluating acute chest pain by hospital or ED observation over a period of several hours, serial electrocardiography and cardiac biomarkers, and subsequent diagnostic testing such as physiologic stress testing is safe and effective. Yet this approach has been criticized for being time intensive and costly. This review evaluates the current medical evidence which has demonstrated the potential for coronary CT angiography (CTA) assessment of acute chest pain to safely reduce ED cost, time to discharge, and rate of hospital admission. These benefits must be weighed against the risk of ionizing radiation exposure and the influence of ED testing on rates of downstream coronary angiography and revascularization. Efforts at radiation minimization have quickly evolved, implementing technology such as prospective electrocardiographic gating and high pitch acquisition to significantly reduce radiation exposure over just a few years. CTA in the ED has demonstrated accuracy, safety, and the ability to reduce ED cost and crowding although its big-picture effect on total hospital and health care system cost extends far beyond the ED. The net effect of CTA is dependent also on the prevalence of coronary artery disease (CAD) in the population where CTA is used, which significantly influences rates of post-CTA invasive procedures such as angiography and coronary revascularization. These potential costs and benefits will warrant careful consideration and prospective monitoring as additional hospitals continue to implement this important technology into their diagnostic regimen.     

Multidetector CT angiography in spontaneous popliteal artery dissection

Primary dissection of the femoropopliteal or popliteal arteries is rare in the absence of involvement of the aorta or aneurysmal arterial changes. In this report, we present multidetector CT angiography findings of a case of a spontaneous nonaneurysmal dissection limited to the left popliteal artery in an otherwise healthy 40-year-old woman.     

Appropriateness of selection criteria for CT examinations performed at an emergency department

In the diagnosis of traumatic and nontraumatic emergencies, computed tomography (CT) is the most frequently performed procedure. The aims of this study were to find out whether CT report results can be used as a reliable tool for the diagnosis and management of patients at an emergency department and to evaluate the appropriateness of the selection criteria for CT examinations. For this reason, we analysed the emergency CT procedures according to the diagnostic hypothesis written on CT request forms, the results of the CT reports and the final diagnosis of the patients. One thousand consecutive CT procedures in the emergency department of a research hospital were retrospectively analysed. When the CT reports and the final diagnosis were evaluated, the sensitivity and specifity of the CT were found to be 0.81 and 0.85. According to the analysis of the CT reports, 55.8 % of all the patients were reported to be normal. When the patient files were examined for the final diagnosis of the patients, 55.7 % of the patients did not receive a final diagnosis related to the diagnostic hypothesis. The lowest correlation was found between the diagnostic hypothesis, the CT reports and the final diagnosis of the patients who underwent cranial CT procedure for trauma. The results of the CT reports can be used as a reliable parameter for the diagnosis and management of the patients at emergency departments. On the other hand, a high negative rate of CT reports was noted especially for the cranial CT examinations. CT selection criteria for the head trauma patients should be reconsidered. Since CT is a procedure involving ionising radiation, it is important that it is performed with the correct indications and the relevant clinical information is specified on the CT request forms.     

Multisection CT angiography compared with catheter angiography in diagnosing vertebral artery dissection

BACKGROUND AND PURPOSE: Multisection CT angiography is a minimally invasive technique that can provide high-resolution and high-contrast images of the arterial lumen and wall. To our knowledge, the ability of multisection CT angiography in detecting vertebral artery (VA) dissection has never been evaluated. We assessed the sensitivity and specificity of a routine, standardized, multisection CT angiographic protocol for the detection of VA dissection. METHODS: We retrospectively reviewed multisection CT angiograms of 17 patients with VA dissection and 17 control subjects. The acquisition protocol for multisection CT angiography was 1.25-mm nominal section thickness, a table speed of 7.5 mm per rotation (9.4 mm/s), and a 0.8-second gantry rotation period. Two radiologists assessed the maximum intensity projection and axial source images. The sensitivity and specificity of this technique in depicting VA dissection were determined. RESULTS: Conventional angiography depicted 15 normal and 19 dissected VAs (including five stenotic, seven occlusive, and seven aneurysmal dissections) in the patient group and 28 normal and six atherosclerotic VAs in the control group. Multisection CT angiography enabled successful diagnosis of all 19 dissected VAs and 48 (98%) of 49 nondissected VAs but misidentified a severe atherosclerotic lesion as an aneurysmal-type dissection. The sensitivity, specificity, accuracy, and positive and negative predictive values of multisection CT angiography in diagnosing VA dissection were 100%, 98%, 98.5%, 95%, and 100%, respectively. CONCLUSION: Multisection CT angiography was a sensitive and accurate technique for the diagnosis of VA dissection.     

肠系膜上动脉夹层的MSCT血管成像

目的:探讨多层螺旋CT血管成像(MSCTA)在诊断肠系膜上动脉夹层(SMAD)中的价值.方法:回顾性分析我院临床漏诊、经CTA诊断为SMAD后经手术或DSA证实的16例患者的临床及CT影像资料.所有患者均行MSC-TA检查,并采用MPR、CPR、MIP和VR技术进行图像后处理.总结SMAD的CTA特征表现,分析临床漏诊的原因.结果:SMAD主要CT表现:16例患者均可见SMA为双腔结构,可见内膜片,其中7例患者假腔内可见新月形充盈缺损.CT横轴面和三维重组图像能清楚显示11例患者肠系膜上动脉夹层的范围和程度.SMAD患者的主要临床表现是急性或慢性腹痛、以中上腹为主,无特异性,临床医师未认识到MSCTA诊断SMAD的价值是导致漏诊或误诊的原因.结论:MSCTA能提供评估肠系膜上动脉夹层的可靠信息,临床医师和影像医师应该认识其价值,重视对肠系膜上动脉夹层的观察.     

Spontaneous renal artery dissection revealed by helical CT angiography

Spontaneous renal artery dissection is rare and may be misdiagnosed because its clinical presentation is confusing. Diagnosis is usually made by intra-arterial angiography. We report a case where a spontaneous renal artery dissection was initially misdiagnosed as a renal abscess. Diagnosis was made later with helical CT for suspicion of renal artery stenosis in a patient with recent onset of hypertension. This unusual case shows that helical CT can be useful for non-invasive diagnosis of renal artery dissection. Received: 20 May 1999; Revised: 2 September 1999; Accepted: 3 September 1999     

CT angiography versus colour-Doppler US in acute dissection of the vertebral artery

PURPOSE: Conventional digital subtraction angiography (DSA) still represents the criterion standard for the diagnosis of vertebral artery dissection (VAD), but the main drawbacks of this technique include invasiveness, patient discomfort and risk of complications. We evaluated the potential of multidetector computed tomography angiography (CTA) as a noninvasive tool providing high-resolution images of the arterial lumen and wall by comparing the diagnostic accuracy of CTA and colour-Doppler ultrasonography (CDUS) in detecting acute VAD. MATERIALS AND METHODS: We retrospectively reviewed 15 cases of VAD in 15 patients (five men and ten women, age range 28-58 years) who came to our attention between August 2001 and September 2005. The diagnosis was made on the basis of appropriate clinical presentation, absence of atherosclerotic disease in the cerebrovascular circulation and evidence of distinctive CT features, which were subsequently confirmed by conventional angiography used as reference standard. All patients with a clinical suspicion of VAD underwent CDUS of the neck vessels prior to CTA. Accuracy, sensitivity and specificity of CDUS and CTA were expressed as percentages of agreement with the reference angiographic procedure. Interreader concordance for detection of VAD by CTA was calculated with the Cohen K value. RESULTS: The CDUS examinations revealed ten out of 15 VAD, with a sensitivity of 66%, a specificity of 60%, a positive predictive value of 55.5% and a negative predictive value of 70.5%. In five cases, CDUS revealed nonspecific wall and flow alterations; in eight patients, high resistance obstructive flow; and in two patients, intimal flap with demonstration of the true and false lumen. CTA enabled the correct identification of all 15 VAD. The reported sensitivity, specificity, positive predictive value and negative predictive value were 100%, 95%, 93.7% and 100%, respectively. With regard to localisation of VAD, CTA showed 100% correlation with DSA. The differences in CTA and CDUS sensitivity (100% vs 66%), specificity (95% vs 60%), and overall diagnostic accuracy (97% vs 62.8%), assessed by cross tabulations and compared by using the McNemar's two-sided test, were significant (p<0.05). CONCLUSIONS: Multidetector CTA is a sensitive technique for the diagnosis of VAD. Used as a complement to unenhanced brain CT, it has the advantage of being readily available and easy to perform.     

Coronary CT angiography versus standard of care for assessment of chest pain in the emergency department

Use of coronary CT angiography (CTA) in the early evaluation of low-intermediate risk chest pain in the emergency department represents a common, appropriate application of CTA in the community. Three large randomized trials (CT-STAT, ACRIN-PA, and ROMICAT II) have compared a coronary CTA strategy with current standard of care evaluations in >3000 patients. These trials consistently show the safety of a negative coronary CT angiogram to identify patients for discharge from the emergency department with low rates of major adverse cardiovascular events, at significantly lower cost, and greater efficiency in terms of time to discharge. Together, these trials provide definitive evidence for the use of coronary CTA in the emergency department in patients with a low-to-intermediate pretest probability of coronary artery disease. Clinical practice guidelines that recommend the use of coronary CTA in the emergency department are warranted.     

Diagnostic accuracy of low-dose 256-slice multi-detector coronary CT angiography using iterative reconstruction in patients with suspected coronary artery disease

Objectives

To evaluate the accuracy of low-dose coronary CTA with iterative reconstruction (IR) in the diagnosis of coronary artery disease (CAD) in patients with suspected CAD.

Methods

Ninety-six patients with suspected CAD underwent low-dose prospective electrocardiogram-gated coronary CTA, with images reconstructed using IR. Image quality (IQ) of coronary segments were graded on a 4-point scale (4, excellent; 1, non-diagnostic). With invasive coronary angiography (ICA) considered the “gold standard”, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of coronary CTA were calculated on segment-, vessel- and patient-based levels. The patient data were divided into two groups (Agatston scores of ≥ 400 and <400). The differences in diagnostic performance between the two groups were tested.

Results

Diagnostic image quality was found in 98.1 % (1,232/1,256) of segments. The sensitivity, specificity, PPV, NPV and accuracy were 90.8 %, 95.3 %, 81.8 %, 97.8 % and 94.3 % (segment-based) and 97.2 %, 83.3 %, 94.6 %, 90.9 % and 93.8 % (patient-based). Significant differences between the two groups were seen in specificity, PPV and accuracy (92.1 % vs. 97.9 %, 76.0 % vs. 86.7 %, 91.7 % vs. 96.6 %, P?<?0.05; segment-based). The average effective dose was 1.30?±?0.15 mSv.

Conclusion

Low-dose prospective coronary CTA with IR can acquire satisfactory image quality and show high diagnostic accuracy in patients with suspected CAD; however, blooming continues to pose a challenge in severely calcified segments.

Key Points

? Coronary artery disease (CAD) is increasingly investigated using coronary CTA. ? The iterative reconstruction (IR) algorithm is promising in decreasing radiation doses. ? Low-dose prospective coronary CTA with IR can acquire satisfactory image quality. ? Low-dose prospective coronary CTA with IR can show high diagnostic accuracy.     

椎动脉CTA对椎动脉型颈椎病的应用研究

目的 研究椎动脉CTA对椎动脉型颈椎病的临床应用价值，探讨周围骨性结构对椎动脉影响的定量关系。方法21例正常对照与23例临床拟诊为椎动脉型颈椎病的患者行椎动脉CTA检查，用多平面重建(MPR)对椎动脉行冠，矢状位重建，分析椎动脉CTA的影像表现特点以及周围骨性结构对其影响的定量关系。结果正常组椎动脉走行较直，病例组13例钩突轻度骨质增生对椎动脉无影响，10例共22处C4-C7，钩突中、重度增生，当轴位钩突最突出点到相应上位椎体中线的垂直距离超过15．86mm时将对椎动脉造成推移或压迫。结论椎动脉CTA可以很好地显示椎动脉及其周围骨性结构，为临床提供更为直观的影像学依据。     

Diagnostic angiography using multi-slice spiral CT in acute obstruction of the basilar artery

OBJECTIVE: To evaluate the diagnostic efficiency of CT angiography in case of clinical signs of acute brainstem infarction for the therapeutic management of catheter-based local thrombolysis. MATERIAL AND METHODS: 3 patients (2 males, 1 female) suffering from an acute onset of brainstem symptoms and being suspicious of an occluded basilar artery were included into this report. 1 patient underwent selective vertebral arteriography. 2 patients were initially examined with CT angiography using a 4-row scanner and 100 ml intravenous contrast agent. RESULTS: In one patient, an occlusion of the basilar artery was excluded with catheter-based angiography. Subsequently, the patient was treated with systemic thrombolysis using r-tPA because of a thalamus infarction seen in MRI. 2 patients who have been initially examined with CT angiography presented with complete occlusions of the basilar arteries. These patients underwent r-tPA thrombolysis by means of superselective micro-catheter approaches of the vertebrobasilar vessels. CT angiography was very useful for determinating the occlusion length of the basilar artery pre-therapeutically, and in 1 case for ruling out an occluded vertrebral artery for catheterization. All patients recovered well under thrombolytic therapy applied systemically or selectively. CONCLUSION: Cerebral multi-slice CT angiography is a fast and save technique for detecting or ruling out an acute basilar artery occlusion. Thus, in cases of equivocal clinical signs CT angiography is recommended before the decision of thrombolytic therapy is made.     

双源CT头颈联合双能量动脉成像肺动脉干监测优化方案研究

目的 探讨肺动脉干监测方案在双源CT头颈部联合双能量CTA成像中的应用价值.方法 60例行头颈部双能量CTA的患者按照随机数字表法分为2组,A组(优化方案组,30例)监测点位于肺动脉主干、阈值150 HU、触发延迟时间为8～9s,螺距0.9,碘海醇(350 mg I/ml)60 ～65 ml;B组(常规方案组,30例)监测点位于主动脉弓、阈值100 HU、触发延迟时间为5 s,碘海醇(350 mg I/ml)60～70 ml.体质量＜75 kg的患者注射流率为4.0 ml/s,体质量≥75 kg或体质量指数(BMI) ≥27 kg/m2者注射流率采用4.5 ml/s,对比剂注射完后以相同流率追加注射40 ml生理盐水.测量2组患者两侧颈总动脉、颈内外动脉、椎基底动脉、大脑中动脉水平段、注射对比剂侧锁骨下静脉、颈静脉近中远段、直窦、上矢状窦的强化CT值.2名有经验的医师采用双能量自动去骨软件、Inspace软件和3D后处理软件,行VR、MIP、CPR成像,双盲法评价CTA图像质量,评价注射对比剂侧锁骨下静脉对比剂残留伪影、头颈部静脉回流等对动脉显影的影响.应用独立样本t检验比较2组图像的CT值、图像质量评分分值等,应用卡方检验比较2组图像对比剂残留伪影、颈根部动脉起始处缺如段数、颈静脉回流严重程度等.结果 两组动脉各段CT值为372 ～414 HU,差异均无统计学意义(P值均＞ 0.05).A组左、右两侧颈静脉内近、中、远段强化CT值[分别为(95±36)、(95±36)HU,(131±58)、(133±57)HU,(174±68)、180±66) HU]明显低于B组[分别为(135±58)、(137±59)HU,(170±58)、(181±58) HU,(218±62)、(224±68) HU],两组间比较,差异有统计学意义(t值为-3.30 ～-2.54,P值均＜0.05).A组注射对比剂侧锁骨下静脉对比剂残留伪影例数(5例)及颈根部动脉起始处缺如段数(11段)少于B组(12例,24段),差异有统计学意义(x2值分别为4.02、5.65,P值均＜0.05).颈内静脉显影程度A组颈总动脉分叉以下轻微5例、严重1例,分叉以上轻微15例、严重9例;B组分叉以下显影轻微9例、严重6例,分叉以上显影轻微12例、严重17例,优化方案能显著减少颈内静脉对颈部动脉显示的干扰(x2分别为6.79、6.37,P值均＜0.05).图像质量评分A组(3.84±0.40)分高于B组(3.64±0.63)分,差异具有统计学意义(=4.26,P＜0.05).结论 肺动脉干监测结合60 ～65 ml对比剂优化双能量头颈部CTA成像方案可以显著减轻颈静脉回流和注射对比剂侧锁骨下静脉对比剂残留伪影,获得良好的图像质量,有一定的临床应用价值.     

Time-resolved CT angiography in aortic dissection

Objectives

We performed this study to assess feasibility and additional diagnostic value of time-resolved CT angiography of the entire aorta in patients with aortic dissection.

Materials and methods

14 consecutive patients with known or suspected aortic dissection (aged 60 ± 9 years) referred for aortic CT angiography were scanned on a dual-source CT scanner (Somatom Definition Flash; Siemens, Forchheim, Germany) using a shuttle mode for multiphasic image acquisition (range 48 cm, time resolution 6 s, 6 phases, 100 kV, 110 mAs/rot). Effective radiation doses were calculated from recorded dose length products. For all phases, CT densities were measured in the aortic lumen and renal parenchyma. From the multiphasic data, 3 phases corresponding to a triphasic standard CT protocol, served as a reference and were compared against findings from the time-resolved datasets.

Results

Mean effective radiation dose was 27.7 ± 3.5 mSv. CT density of the true lumen peaked at 355 ± 53 HU. Compared to the simulated triphasic protocol, time-resolved CT angiography added diagnostic information regarding a number of important findings: the enhancement delay between true and false lumen (n = 14); the degree of membrane oscillation (n = 14); the perfusion delay in arteries originating from the false lumen (n = 9). Other additional information included true lumen collapse (n = 4), quantitative assessment of renal perfusion asymmetry (n = 2), and dynamic occlusion of aortic branches (n = 2). In 3/14 patients (21%), these additional findings of the multiphasic protocol altered patient management.

Conclusions

Multiphasic, time-resolved CT angiography covering the entire aorta is feasible at a reasonable effective radiation dose and adds significant diagnostic information with therapeutic consequences in patients with aortic dissection.     

Preliminary experience using contrast-enhanced MR angiography to assess vertebral artery structure for the follow-up of suspected dissection.

BACKGROUND AND PURPOSE: Important advances have been made recently in MR angiography with the use of contrast medium injection, which has proved valuable for the imaging of vertebral arteries (VAs) obtained during short scanning times. Our purpose was to assess the feasability of contrast-enhanced fast 3D MR angiography for imaging VAs and to evaluate the long-term follow-up of VA dissections. METHODS: Sixteen consecutive patients with 18 angiographically documented VA dissections (seven occlusive dissections and 11 stenotic dissections, including two each with a pseudoaneurysm) were followed up using both contrast-enhanced 3D MR angiography and cervical T1-weighted MR imaging at a median delay of 22 months. Ten patients underwent MR imaging at the acute phase as well, and nine underwent early follow-up angiography at a median delay of 3 months. MR angiographic findings were determined by consensus, focussing on image quality, presence of residual stenosis, luminal irregularities, and occlusion. RESULTS: Of the 32 VAs, a segment of the artery was not assessable on contrast-enhanced MR angiography in each of four small VAs. A central signal void artifact of cervical arteries was seen in one patient and motion artifacts were seen in two, but images could be interpreted. A venous enhancement was detected in 10 of 16 examinations, but this did not prevent image analysis. Ten of 11 stenotic dissections returned to normal, whereas one stenotic dissection progressed to occlusion. Two pseudoaneurysms detected by initial angiography resolved spontaneously; one was revealed only by delayed MR angiography, and one was detected on an early MR angiogram and proved resolved on a late MR angiogram. Of the seven initially occluded VAs, five reopened, with a hairline residual lumen in each of three. CONCLUSION: This preliminary experience showed that contrast-enhanced MR angiography is a promising tool for imaging VAs; it allows the assessment of VA dissection changes over time. Most lesions tended to heal spontaneously, but persisting occlusion or pseudoaneurysm could be detected during the late course.     

自发性腹腔干夹层的MSCT血管成像表现

【摘要】目的：总结自发性腹腔干夹层的MSCT血管成像表现。方法：回顾性分析14例自发性腹腔干夹层患者的临床及MSCT血管成像表现。结果：14例患者中自发性腹腔干夹层10例（71.4%,10/14）,腹腔干和肠系膜上动脉夹层4例（28.6%,4/14）。14条腹腔干血管和4条肠系膜上动脉夹层均显示了内膜片、破口及真假腔,3条血管夹层合并血栓,2条夹层血管合并钙化,2例患者合并周围血肿,1例合并脾梗死。14条腹腔干夹层中6条血管夹层伴有动脉瘤样突起,4条肠系膜上动脉夹层均伴有动脉瘤样突起。2例患者行DSA检查,DSA表现与MSCT血管成像表现一致,1例行支架植入术后复查见支架内血栓形成。结论：MSCT血管成像能敏感地显示腹腔干夹层的病理改变,可作为其诊断和随访的首选检查方法。     

Spiral CT angiography of aortic dissection

Spiral CT angiography (CTA) is one of the newest imaging techniques used for the evaluation of aortic dissection. Current spiral CT scanners with high-performance tubes and subsecond scanning allow increased regions of coverage. Large volumes of data are rapidly acquired through the aorta during maximum contrast enhancement. Multiplanar reformat (MPR), curved planar reformat (CPR), and 3-D rendering techniques including shaded surface display (SSD) and maximum intensity projection (MIP) are then applied to the data to generate CT angiographic images of the aorta. Emergent spiral CTA may be performed in patients with suspected aortic dissection who are hemodynamically stable. Postprocessing is performed immediately following data acquisition and can provide additional information for aortic dissection diagnosis and clinical management. The technique, applications, and limitations of spiral CTA for the evaluation of aortic dissection will be discussed relative to the role of other imaging modalities.     

Diagnostic performance of multidetector CT angiography for assessment of coronary artery disease: meta-analysis

PURPOSE: To review the literature on the diagnostic performance of multidetector computed tomographic (CT) angiography for assessment of symptomatic coronary artery disease, with conventional coronary angiography as the reference standard. MATERIALS AND METHODS: A PubMed and manual search of the literature published between January 1998 and May 2006 on use of multidetector CT angiography compared with coronary angiography in patients with symptomatic coronary artery disease was performed. Summary estimates of diagnostic odds ratio, sensitivity, and specificity were calculated. Random-effects models were used to compare the diagnostic performance of four-, 16-, and 64-detector CT angiographic units, and the proportion of nonassessable coronary arterial segments was evaluated. RESULTS: Fifty-four studies were included in the meta-analysis: 22 studies with four-detector CT angiography, 26 with 16-detector CT angiography, and six with 64-detector CT angiography. The pooled sensitivity and specificity for detecting a greater than 50% stenosis per segment were 0.93 (95% confidence interval [CI]: 0.88, 0.97) and 0.96 (95% CI: 0.96, 0.97) for 64-detector CT angiography, 0.83 (95% CI: 0.76, 0.90) and 0.96 (95% CI: 0.95, 0.97) for 16-detector CT angiography, and 0.84 (95% CI: 0.81, 0.88) and 0.93 (95% CI: 0.91, 0.95) for four-detector CT angiography, respectively. Results of regression analysis indicated that the diagnostic performance significantly improved with the newer generations of multidetector CT scanners (64- and 16-detector vs four-detector units), adjusted for exclusion of nonassessable segments, and contrast agent concentration used (P < .05). Simultaneously, the nonassessable proportion of segments significantly decreased with the newer generations of multidetector CT scanners, adjusted for heart rate, prevalence of significant disease, and mean age. CONCLUSION: With the newer generations of multidetector CT scanners, the diagnostic performance for the assessment of coronary artery disease has significantly improved, and the proportion of nonassessable segments has decreased.