CT血流灌注参数对于肾动脉狭窄的肾脏血流研究价值

目的:探讨利用CT血流灌注参数研究肾动脉狭窄患者肾脏血流状况.方法:高血压患者34人,分为肾动脉狭窄组(23人)和对照组(11人),通过肾脏电影扫描获得的CT时间密度曲线测量肾脏皮质血流量,分析肾脏皮质血流量与肾动脉狭窄程度的关系.结果:肾动脉狭窄程度 ＜50%、50%～75%、＞75%肾皮质血流量(RBF)分别是 268±47.2ml/100g/min,227±39.2ml/100g/min, 225±88.2ml/100g/min,对照组RBF 345±62ml/100g/min.肾动脉狭窄＞50%的肾皮质血流量与对照组有明显差别(P＜0.05).结论:明显肾动脉狭窄的肾脏皮质RBF下降,CT血流灌注参数可以评估肾动脉狭窄导致的肾脏血流改变.     

急性主动脉夹层患者320排CT肾脏灌注研究

目的:研究主动脉夹层的患者肾脏的CT灌注特点,评价其指导手术的意义。方法:采用东芝公司AQUIL-ION ONE 320排CT,对30名诊断主动脉夹层的患者,术前进行双肾血流灌注检查,测量肾血流量参数值。根据肾动脉受累情况,分为真腔组、假腔组、夹层组、骑跨组。真腔组为肾动脉未受累,假腔组为肾动脉起自假腔,夹层组为肾动脉可见内膜片,骑跨组为肾动脉开口骑跨内膜破口。结果:30名患者,右肾动脉正常22例,受累8例,其中右肾动脉起自假腔6例,骑跨内膜破口2例;左肾动脉正常16例,受累14例,其中左肾动脉起自假腔9例,骑跨3例,夹层2例。真腔组、假腔组、夹层组、骑跨组肾皮质血流量参数平均值分别为305.2±7.7,311.2±11.7,126.2±11.6,364.5±12.0;肾髓质血流量参数平均值分别为175.9±7.8,173.2±12.1,89.7±15.3,231.3±8.0。采用t检验,真腔组与夹层组、骑跨组差异显著,P<0.05;与假腔组血流量参数值差异不显著,P>0.05;骑跨组肾血流量大于真腔组、假腔组,夹层组肾血流量小于真腔组、假腔组。结论:肾脏动态CT灌注不但可以观察肾动脉有无夹层或狭窄,还可以反映肾脏的微循环改变。研究主动脉夹层的患者肾脏的CT灌注特点,通过测量肾血流量以判定肾脏的功能,有助于术前的充分准备,指导术中、术后治疗方案,具有重要的临床意义。     

多层CT血管成像在老年肾动脉狭窄相关疾病中的应用价值

目的:以数字减影血管造影(DSA)为参考标准,探讨多层CT血管成像(MDCTA)在无创诊断老年肾动脉狭窄相关性疾病中的应用价值。方法:对我院2012年1月至2014年3月经DSA证实的老年肾动脉狭窄相关疾病患者48例(男性27例,女性21例,年龄65~79岁,平均年龄71±5岁),于DSA术前行MDCTA前瞻性对照研究,观察MDCTA显示肾动脉狭窄的程度、位置、形态和数目等情况,并对不同病因所引起的肾动脉狭窄进行CT影像分析。结果:48例肾动脉狭窄相关疾病包括动脉粥样硬化性肾动脉狭窄42例、大动脉炎1例、先天性肾动脉发育不良1例、肾动脉纤维性肌性结构不良1例、肾动脉瘤1例、自发性肾动脉夹层1例和腹膜后肿瘤压迫1例。DSA证实狭窄肾动脉60支,均为主肾动脉,其中双侧26例,左侧5例,右侧3例。起始部狭窄48支,中部狭窄3支,全程狭窄9支。MDCTA显示血管狭窄65例,其敏感度为100%,特异度为87.8%,准确度为95.1%,阳性预测值为92.3%,阴性预测值为100%。狭窄程度MDCTA分级:0级36支,Ⅰ级20支,Ⅱ级29支,Ⅲ级11支,Ⅳ级5支;DSA分级:0级41支,Ⅰ级19支,Ⅱ级27支,Ⅲ级10支,Ⅳ级4支,两种检查方法评价肾动脉狭窄程度差异无统计学意义(Pearsonχ2=0.5805,P=0.965)。结论:MDCTA能清晰显示肾动脉狭窄的位置、数目和形态,并精确评价其狭窄程度和鉴别肾动脉狭窄相关性疾病的病因,可作为老年肾动脉相关性疾病无创性诊断的首选方法。     

CT脑灌注评估颈动脉狭窄的血流动力学改变

目的 评价CT脑灌注在评估颈动脉狭窄患者的脑血流动力学改变中的应用价值.方法 对50例临床诊断为可疑颈动脉狭窄的患者进行常规头颅CT平扫,CT灌注扫描(CT perfusion,CTP)及CT血管成像扫描(CT angiography,CTA).CTP可获得脑血流量(CBF),脑血容量(CBV),平均通过时间(MTT)及达峰时间(TTP)等灌注参数图,CTA采用CPR,MPR及VR等重建方式重建头颈部血管.观察CTA所示的颈动脉狭窄率与CTP灌注参数变化间的关系.结果 38例单侧颈动脉狭窄患者中,10例轻度狭窄者,患侧各灌注参数变化与健侧各参数无统计学差异,9例中度狭窄与19例重度狭窄及闭塞患者中,患侧MTT与TTP较健侧显著延长,而CBF与CBV无明显变化.结论 灌注参数MTT与TTP能敏感地显示颈动脉中重度狭窄或闭塞患者的血流动力学改变,是诊断脑缺血最敏感的指标,为临床早期治疗提供可靠的依据,从而预防脑卒中的发生.     

动脉粥样硬化性肾动脉狭窄与高血压相关性的MDCTA研究

目的利用MDCTA评价动脉粥样硬化性肾动脉狭窄与高血压之间的相关性。方法对42例动脉粥样硬化性肾动脉狭窄的高血压患者的多层螺旋CT血管成像进行重建、分析,判断肾动脉狭窄的程度,对观察者间的一致性进行评价,并将肾动脉狭窄评分与血压进行相关性分析。结果 MDCTA评价肾动脉狭窄的观察者间一致性较好,kappa值为0.71。42例患者中,22例为双侧肾动脉狭窄,20例为单侧肾动脉狭窄,共64支狭窄肾动脉,其中钙化性斑块32支,混合性斑块21支,非钙化性斑块11支,狭窄部位均为肾动脉近段。肾动脉狭窄评分与收缩压及舒张压呈正的直线相关,相关系数r为0.834,决定系数R2为0.695。结论 MDCTA是评价动脉粥样硬化性肾动脉狭窄的最佳无创性检查手段之一,粥样硬化性肾动脉狭窄的程度与高血压之间存在正性直线相关。     

原发性高血压肾脏血流的多层螺旋CT灌注研究

目的利用多层螺旋CT(MSCT)灌注扫描研究原发性高血压病肾脏血流变化,探讨其在诊断高血压病早期肾损害的价值。资料与方法将原发性高血压病患者分为两组:无早期肾损害组和早期肾损害组。应用MSCT灌注扫描检查,测量血流量(BF)、血容量(BV)和平均通过时间(MTT)等,并与核医学肾脏有效血浆流量(ERPF)进行比较。结果高血压组整肾、皮质和髓质的BF值均低于对照组,其中高血压有早期肾损害组下降明显,3组间差异均有统计学意义。高血压病组整肾BV下降,与正常组比较,高血压有早期肾损害组差异有统计学意义(P<0.05),而高血压无早期肾损害组差异无统计学意义(P>0.05)。高血压病组MTT延长,与正常组比较差异无统计学意义。高血压病组整肾BF与ERPF线性相关。结论MSCT可对原发性高血压病患者组织血流变化进行动态观察,早期诊断和预测高血压病肾脏损害。     

256层螺旋CT脑灌注成像与颈内动脉狭窄的相关性研究

目的：应用256层螺旋CT探讨颈内动脉狭窄和闭塞与脑灌注降低的相关性。方法：对76例患者进行CTA和CTP联合检查,根据CTA图像选出颈内动脉无狭窄者为对照组,其余患者进行颈内动脉狭窄分级,分轻、中、重三级,每级独立分析研究。所有患者均选择感兴趣区进行脑灌注成像CBV、CBF、MTT、TTP测量,单侧颈内动脉狭窄者病变侧与健侧对比,进行配对t检验。双侧颈内动脉狭窄者与对照组对比,进行独立样本t检验。结果：颈内动脉无狭窄者共15例,CBV CBF MTT TTP值分别为（分水岭区2.5±0.6;38±12;5.4±0.6;21±6。基底节区5.5±0.4;95±15;3.2±1.1;20±5）。单侧颈内动脉狭窄者共33例,其中轻中度狭窄者各为12例,且CBV、CBF、MTT、TTP四项差异均无统计学意义（P〉0.05）,重度狭窄者9例,分水岭区CBF、MTT差异有高度统计学意义（P〈0.01）,TTP差异有统计学意义（P〈0.05）,CBV差异无统计学意义（P〉0.05）。基底节区MTT差异有高度统计学意义（P〈0.01）,CBF差异有统计学意义（P〈0.05）,CBV、TTP差异无统计学意义（P〉0.05）。双侧颈内动脉狭窄者共28例,重度狭窄者11例,CBF、MTT差异有统计学意义（P〈0.05）。结论：受侧枝循环等多种因素影响,颈内动脉重度狭窄或闭塞与脑内血流灌注降低有相关性,轻中度狭窄与脑灌注降低无明显相关性。     

肾功能不全动物模型的CT灌注成像研究

目的 分析猪单侧肾动脉狭窄（RAS）和输尿管不全梗阻（UPO）模型的CT灌注成像特征,评估灌注参数与肾小球滤过率（GFR）的相关性。材料与方法 选用24只中华实验猪并随机分为RAS组、UPO组和正常对照组,每组8只。通过手术建立猪左侧RAS及左侧UPO模型,并行双肾区容积螺旋穿梭CT灌注成像及99Tcm-DTPA动态核素显像。描绘全肾皮质获得时间-密度曲线及CT灌注参数[血流量（BF）、血容量（BV）、平均通过时间（MTT）和毛细血管表面通透性（PS）],评价肾皮质灌注参数与99Tcm-DTPA动态核素肾图获得的GFR的相关性。结果 RAS组及UPO组患侧肾皮质时间-密度曲线开始上升的时间明显延迟且上升段平缓,波峰延迟且明显低于健侧。RAS组BF明显低于健侧,MTT较健侧明显延长（t=3.594、-3.613,P=0.011）;与对照组比较,MTT明显延长（P=0.033）。UPO组BF明显低于健侧,MTT较健侧明显延长（t=10.244、-4.808,P均<0.01）;与对照组比较,患侧肾BF及BV明显下降,MTT明显延长（P均<0.05）。双侧、患侧肾皮质BF、MTT与...     

多排螺旋CT扫描对急性肾功能衰竭肾脏血流灌注研究

目的 :通过CT扫描测量肾脏组织血流灌注值 ,探讨螺旋CT对急性肾功能衰竭肾脏血流灌注变化的反映能力。方法 :实验动物分为急性肾功能衰竭组和对照组 ,用核医学肾脏动态显像作为参考指标。利用多排螺旋CT扫描机 ,获得肾皮质、肾外髓质和全肾血流灌注值。结果 :肾功能衰竭组单位体积肾脏、肾皮质血流灌注量明显低于对照组 ,差异非常显著 (P<0 .0 1) ,肾脏外髓质的血流量仅有轻微下降 ,但两组之间无显著性差异 (P>0 .0 5 )。结论 :螺旋CT能够反映急性肾脏功能衰竭肾脏血流量的变化。急性肾脏功能衰竭肾脏血流量的下降出现在肾脏皮质 ,而肾脏外髓质血流量无改变。     

CT灌注观察脑出血后血肿周围组织血流灌注变化

目的:探讨脑出血患者血肿周围组织血流的动态变化规律。方法:脑出血患者59例,分别在入组时、入组后7d、14d、28d应用CT灌注测量血肿周围组织的局部脑血流量(rCBF)、局部脑血容量(rCBV)、对比剂平均通过时间(MTT)、对比剂峰值时间(TTP)参数数值,计算脑岀血侧(患侧)与其健侧镜像部位各参数的比值,并进行对比分析。结果:脑出血后rCBF、rCBV 7d时最低,随后逐渐升高,其患侧与健侧比值各时相点均<1。MTT与TTP 7d时达高峰,随后逐渐缩短,其患侧与健侧比值各时相点均>1。结论:脑出血后血肿周围组织存在持续的低灌注状态,且这种低灌注状态随时间改变呈波动性的变化规律。     

Transplant renal artery stenosis: Evaluation with contrast-enhanced ultrasound

ObjectiveTo assess the efficacy of contrast-enhanced ultrasound (CEUS) in depicting transplant renal artery stenosis (TRAS).Materials and methodsSeventy-eight patients (56 men and 22 women; aged 36 ± 12.2 years) who were suspected of TRAS due to either Doppler ultrasound (DUS) abnormalities or difficult control of blood pressure and/or persistent deterioration of renal function were enrolled to perform CEUS. The reference standard for the TRAS diagnoses was computed tomography angiography (CTA). The diagnostic performance of DUS and CEUS parameters was assessed by the area under the receiver operating characteristic curve (AUC).ResultsTRAS was diagnosed in 32 out of 78 cases by CTA. The AUC, accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of CEUS in predicting TRAS were 0.92, 92.3%, 87.5%, 95.7%, 93.3%, and 91.7%, respectively. CEUS rectified 13 (28.3%) false-positive cases on DUS, which were confirmed by CTA. Compared to DUS parameters, CEUS showed the highest AUC, statistically significant differences of AUC were found (P = 0.006–0.039), except for that of the PSV ratio in the main transplant renal artery to that in interlobar artery (PSV-ratio) (AUC: 0.92 versus 0.86, P = 0.422). However, CEUS showed a significantly higher specificity (95.7% versus 76.1%, P = 0.008) and the same sensitivity compared to PSV-ratio.ConclusionsCEUS is superior to DUS in depicting TRAS. Moreover, our results suggest that CEUS might potentially be used as a noninvasive tool to spare many patients from unnecessary CTA.     

Variability of clinical CT perfusion measurements in patients with carotid stenosis

Introduction CT perfusion imaging (pCT) may be used to detect and monitor hemodynamic abnormalities due to cerebrovascular disease. The magnitude of variability in clinical measurements has been insufficiently evaluated. The purpose of this study was to measure the long-term variability of clinical pCT measurements in patients with cerebrovascular disease. Methods pCT parameters were calculated for the cerebral hemisphere contralateral to a carotid stenosis before and after stent treatment of stenosis in 33 consecutive patients. Mean transit time (MTT), cerebral blood flow (CBF), and cerebral blood volume (CBV) calculated from pCT data from both a small and large region of interest (ROI) using both manual and automated methods were compared before and after stent treatment. Differences between the first and second measurement were tested for statistical significance with at-test. Variability was calculated as the standard deviation of the differences divided by the mean of the pre- and post-stent treatment values. To adjust for proportional bias, the Bland–Altman analysis was applied. Results The differences between the two measurements of MTT, CBF, and CBV averaged 2.5 to 7.7% when a manual method was used and was higher with automatic methods (p > 0.07). The variability of the values was 18% for MTT, 19% for CBV, and 25% for CBF with the large ROI and the manual method of calculation. The magnitude was larger when the small ROI and automatic methods were employed. Conclusion Longitudinal measurements of MTT, CBV, or CBF by pCT may vary by 20–25%. To detect changes in treatment-related changes in perfusion, pCT studies must be designed to achieve statistical significance based on this variability.     

Dynamic perfusion CT: optimizing the temporal resolution for the calculation of perfusion CT parameters in stroke patients

PURPOSE: To assess the influence of different temporal sampling rates on the accuracy of the results from cerebral perfusion CTs in patients with an acute ischemic stroke. MATERIAL AND METHODS: Thirty consecutive patients with acute stroke symptoms received a dynamic perfusion CT (LightSpeed 16, GE). Forty millilitres of iomeprol (Imeron 400) were administered at an injection rate of 4 ml/s. After a scan delay of 7s, two adjacent 10mm slices at 80 kV and 190 mA were acquired in a cine mode technique with a cine duration of 49 s. Parametric maps for the blood flow (BF), blood volume (BV) and mean transit time (MTT) were calculated for temporal sampling intervals of 0.5, 1, 2, 3 and 4s using GE's Perfusion 3 software package. In addition to the quantitative ROI data analysis, a visual perfusion map analysis was performed. RESULTS: The perfusion analysis proved to be technically feasible with all patients. The calculated perfusion values revealed significant differences with regard to the BF, BV and MTT, depending on the employed temporal resolution. The perfusion contrast between ischemic lesions and healthy brain tissue decreased continuously at the lower temporal resolutions. The visual analysis revealed that ischemic lesions were best depicted with sampling intervals of 0.5 and 1s. CONCLUSION: We recommend a temporal scan resolution of two images per second for the best detection and depiction of ischemic areas.     

Spiral CT angiography of renal arteries: comparison with angiography

A prospective study was carried out to determine the accuracy of spiral CT angiography (CTA) in the detection of renal artery stenosis (RAS). Eighty-two patients with arterial hypertension underwent CTA and digital subtraction angiography (DSA) to exclude RAS. For CTA a contrast medium bolus of 100–150 ml (flow rate 3 ml/s) was injected. A 24 or 40 s CTA was started at the origin of the superior mesenteric artery after a delay time determined by test bolus injection (collimation = 2 mm, pitch = 1/1.5). For stenosis detection transverse images supported by maximum intensity projections (MIP) or multiplanar reconstruction projections were used. Of 197 renal arteries examined (including 33 accessory arteries), 34 RAS were visualized using DSA. With CTA, one hemodynamic RAS was missed and one additional hemodynamic RAS was found. Sensitivity/specificity was calculated to be 94 %/98 %. For hemodynamically relevant RAS (> 50 %) the sensitivity/specificity was 96 %/99 %. CTA additionally depicted five adrenal masses. The high accuracy rate of RAS detection thus allows the use of CTA as a screening method in patients with arterial hypertension to exclude a renovascular cause. Received: 23 June 1997; Revision received: 6 January 1998; Accepted: 29 April 1998     

Carotid bifurcation calcium and correlation with percent stenosis of the internal carotid artery on CT angiography

The aim of this paper was to determine the correlation between calcium burden (expressed as a volume) and extent of stenosis of the origin of the internal carotid artery (ICA) by CT angiography (CTA). Previous studies have shown that calcification in the coronary arteries correlates with significant vessel stenosis, and severe calcification (measured by CT) in the carotid siphon correlates with significant (greater than 50% stenosis) as determined angiographically. Sixty-one patients (age range 50–85 years) underwent CT of the neck with intravenous administration of iodinated contrast for a variety of conditions. Images were obtained with a helical multidetector array CT scanner and reviewed on a three-dimensional workstation. A single observer manipulated window and level to segment calcified plaque from vascular enhancement in order to quantify vascular calcium volume (cc) in the region of the bifurcation of the common carotid artery/ICA origin, and to measure the extent of ICA stenosis near the origin. A total of 117 common carotid artery bifurcations were reviewed. A significant stenosis was defined arbitrarily as >40% (to detect lesions before they become hemodynamically significant) of luminal diameter on CTA using NASCET-like criteria. All significant stenoses (21 out of 117 carotid bifurcations) had measurable calcium. We found a relatively strong correlation between percent stenosis and the calcium volume (Pearsons r = 0.65, P<0.0001). We also found that there was an even stronger correlation between the square root of the calcium volume and the percent stenosis as measured by CTA (r= 0.77, P<0.0001). Calcium volumes of 0.01, 0.03, 0.06, 0.09 and 0.12 cc were used as thresholds to evaluate for a significant stenosis. A receiver operating characteristic (ROC) curve demonstrated that thresholds of 0.06 cc (sensitivity 88%, specificity 87%) and 0.03 cc (sensitivity 94%, specificity 76%) generated the best combinations of sensitivity and specificity. Hence, this preliminary study demonstrates a relatively strong relationship between volume of calcium at the carotid bifurcation in the neck (measured by CT) and percent stenosis of the ICA below the skull base (as measured by CTA). Use of calcium volume measurements as a threshold may be both sensitive and specific for the detection of significant ICA stenosis. The significance of the correlation between calcium volume and ICA stenosis is that potentially a score can be obtained that will identify those at risk for high grade carotid stenosis.Presented at the 41st Annual Meeting of the American Society of Neuroradiology, Washington D.C., 2003. Sean Casey, MD and Charles Truwit, MD are members of the Medical Advisory Board of Vital Images (Plymouth, Minnesota), the company that developed the Vitrea 2 software.     

Total-liver-volume perfusion CT using 3-D image fusion to improve detection and characterization of liver metastases

The purpose of this study was to evaluate the feasibility of a total-liver-volume perfusion CT (CTP) technique for the detection and characterization of liver metastases. Twenty patients underwent helical CT of the total liver volume before and 11 times after intravenous contrast-material injection. To decrease distortion artifacts, all phases were co-registered using 3-D image fusion before creating blood-flow maps. Lesion-based sensitivity and specificity for liver metastases of first the conventional four phases (unenhanced, arterial, portal venous, and equilibrium) and later all 12 phases including blood-flow maps were determined as compared to intraoperative ultrasound and surgical exploration. Arterial and portal venous perfusion was calculated for normal-appearing and metastatic liver tissue. Total-liver-volume perfusion values were comparable to studies using single-level CTP. Compared to four-phase CT, total -liver-volume CTP increased sensitivity to 89.2 from 78.4% (P = 0.046) and specificity to 82.6 from 78.3% (P = 0.074). Total -liver-volume CTP is a noninvasive, quantitative, and feasible technique. Preliminary results suggest an improved detection of liver metastases for CTP compared to four-phase CT.     

Validation and absolute quantification of MR perfusion compared with CT perfusion in patients with unilateral cerebral arterial stenosis

Objective

The aim of the study was to assess absolute quantification of dynamic susceptibility contrast-enhanced magnetic resonance perfusion (MRP) comparing with computed tomography perfusion (CTP) in patients with unilateral stenosis.

Materials and methods

We retrospectively post-processed MRP in 20 patients with unilateral occlusion or stenosis of >79% at the internal carotid artery or the middle cerebral artery (MCA). Absolute quantification of MRP was performed after applying the following techniques: cerebrospinal fluid removal, vessel removal, and automatic segmentation of brain to calculate the scaling factors to convert relative cerebral blood volume (rCBV) and relative cerebral blood flow (rCBF) values to absolute values. For comparison between MRP and CTP, we manually deposited regions of interest in bilateral MCA territories at the level containing the body of the lateral ventricle.

Results

The correlation between MRP and CTP was best for mean transit time (MTT) (r = 0.83), followed by cerebral blood flow (CBF) (r = 0.52) and cerebral blood volume (CBV) (r = 0.43). There was no significant difference between CTP and MRP for CBV, CBF, and MTT on the lesion side, the contralateral side, the lesion-contralateral differences, or the lesion-to-contralateral ratios (P > 0.05). The mean differences between MRP and CTP were as follows: CBV −0.57 mL/100 g, CBF 2.50 mL/100 g/min, and MTT −0.90 s.

Conclusion

Absolute quantification of MRP is possible. Using the proposed method, measured values of MRP and CTP had acceptable linear correlation and quantitative agreement.     

螺旋CT血管造影及血管仿真内镜技术对肾动脉狭窄的诊断与评价

目的：探讨螺旋CT血管造影（SCTA）及血管仿真内镜技术（CTVE）在肾动脉狭窄（RAS）诊断中临床应用价值。方法：7例RAS及1例RAS肾切主后患者行肾动脉SCTA及三维重建，三维重建方法包括：表面遮盖成像（SSD）和最大密度投影（MIP）。3例同时行肾动脉血管CTVE成像。结果：SCTA2DCT图像显示7例RAS患侧肾体积明显缩小，肾皮质明显变薄，无或部分强化。7例RASSSD和MIP均可清晰显示肾动脉主干狭窄的部位、狭窄程度与范围，但不能显示肾段较小肾动脉的狭窄情况。1例RAS肾切除术后MIP和SSD未见肾动脉有其分支显示。3例肾血管CTVE能显示狭窄的肾动脉开口及管腔明显变窄。结论：SCTA及CTVE是诊断肾动脉主干狭窄的有效方法，基本上可代替动脉血管造影。     

Preoperative evaluation of live renal donors using multislice CT angiography

AIM: To determine the accuracy of multidetector row CT renal angiography in the preoperative evaluation of live kidney donors, and to identify potential pitfalls when reporting. METHODS: Between July 1998 and June 2003, 74 consecutive live renal donors underwent contrast-enhanced multidetector row CT renal angiography before donor nephrectomy. The operative notes and radiological reports of all cases were reviewed retrospectively. Where a significant discrepancy was identified, the archived images were reviewed by two radiologists in the light of the intraoperative findings. RESULTS: A total of 12 discrepancies were identified in 11 of the 74 cases (15%). In the preoperative CT angiography reports, 4 accessory arteries, 6 early-branching renal arteries, 1 duplicated renal vein and 1 accessory ureter were not identified; 9 of these were evident on review, but were not detected at the time of reporting. In 3 cases (1 accessory artery, the duplicated renal vein and the accessory ureter), the anomaly was not visible on review of the CT angiographic data, even with the benefit of hindsight. Surgical feedback during the study period resulted in modifications to CT technique and improved performance. CONCLUSION: In the majority of cases, there was good correlation between preoperative CT renal angiography and operative findings. Most discrepancies were due either to an oversight by the reporting radiologist, or failure to fully appreciate the potential surgical significance of certain findings. Regular surgical feedback plays a valuable role in improving reporting accuracy and maintaining imaging standards.     

Optimal sequence timing of CT angiography and perfusion CT in patients with stroke

Objective

Standard stroke CT protocols start with non-enhanced CT followed by perfusion-CT (PCT) and end with CTA. We aimed to evaluate the influence of the sequence of PCT and CTA on quantitative perfusion parameters, venous contrast enhancement and examination time to save critical time in the therapeutic window in stroke patients.

Methods and materials

Stroke CT data sets of 85 patients, 47 patients with CTA before PCT (group A) and 38 with CTA after PCT (group B) were retrospectively analyzed by two experienced neuroradiologists. Parameter maps of cerebral blood flow, cerebral blood volume, time to peak and mean transit time and contrast enhancements (arterial and venous) were compared.

Results

Both readers rated contrast of brain-supplying arteries to be equal in both groups (p = 0.55 (intracranial) and p = 0.73 (extracranial)) although the extent of venous superimposition of the ICA was rated higher in group B (p = 0.04). Quantitative perfusion parameters did not significantly differ between the groups (all p > 0.18), while the extent of venous superimposition of the ICA was rated higher in group B (p = 0.04). The time to complete the diagnostic CT examination was significantly shorter for group A (p < 0.01).

Conclusion

Performing CTA directly after NECT has no significant effect on PCT parameters and avoids venous preloading in CTA, while examination times were significantly shorter.