Assessment of renal hemodynamics and function in pigs with 64-section multidetector CT: comparison with electron-beam CT

PURPOSE: To prospectively evaluate the feasibility of obtaining reliable measurements of renal hemodynamics and function by using 64-section multidetector CT. MATERIALS AND METHODS: This study was approved by the Institutional Animal Care and Use Committee. Eight pigs (two with induced unilateral renal artery stenosis) were studied with both electron-beam CT and 64-section multidetector CT at 1-week intervals in randomized order. Both kidneys were scanned repeatedly, without table movement, for about 3 minutes after intravenous (IV) administration of a bolus of contrast medium and again during vasodilator challenge (acetylcholine). Images were reconstructed on each CT console but were analyzed on the same independent workstation. Attenuation changes in the kidneys were plotted as function of time, and time-attenuation curves (TACs) were subsequently analyzed to determine regional perfusion and volume, glomerular filtration rate (GFR), and renal blood flow (RBF). Statistical analysis utilized Student t test, analysis of variance (ANOVA), linear regression, and Bland-Altman analysis. RESULTS: TACs obtained with multidetector CT were qualitatively similar to those obtained with electron-beam CT, as were the quantitative values of renal perfusion and function. RBF correlated significantly between the two techniques (RBF(MD) = 0.96 . RBF(EB) mL/min; R = 0.77, P < .01). GFR(MD) was also similar to GFR(EB) (77.6 +/- 8.3 vs 79.8 +/- 8.8 mL/min, p > .05). Bland-Altman plots showed good agreement between the two techniques. Both techniques similarly detected the differences between stenotic and contralateral kidneys. CONCLUSION: The clinical multidetector CT scanner provides reliable measurements of single-kidney hemodynamics and function, which are similar to those obtained with previously validated electron-beam CT.     

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。     

Asymmetry of the renal nephrograms on CT: significance of the unilateral prolonged cortical nephrogram

The finding of asymmetry in the renal nephrograms as manifested by a unilateral prolonged cortical nephrogram on dynamic contrast-enhanced CT examinations signifies the presence of an abnormality of renal parenchymal perfusion and/or tubular transit. The differential diagnostic possibilities include stenosis or long-standing occlusion of the renal artery, renal vein thrombosis, and urinary tract obstruction.     

孤立肺结节的增强CT诊断新进展

孤立肺结节(SPN)的增强CT诊断是近年来研究热点之一,检查方法分为动态和多期增强扫描两类,以SPN的强化程度、结节-主动脉强化值比(S/A)、时间-密度曲线类型、灌注值、强化模式、肿瘤血管征等作为诊断依据。以强化值<15HU、S/A<6%为界值,可区分出良性结节;时间-密度曲线类型有助于恶性与炎性结节的鉴别;肿瘤血管征可作为特异性诊断指征;包膜样强化或内壁规则的周围强化高度提示结核的诊断。     

Hemodynamic segmentation of MR perfusion images in patients with unilateral carotid stenosis using independent component analysis

Purpose

To assess spatiotemporal patterns of local perfusion in MR brain perfusion images for patients with unilateral carotid stenosis.

Materials and Methods

MR perfusion images acquired from 12 patients with unilateral carotid stenosis were retrospectively segmented using independent component analysis. Regions of interest selected from the segmentation results were used to measure the time to peak (TTP), time to maximum of the residue curve (T_max), and mean transit time (MTT) for arteries and brain parenchyma on normal and stenotic sides.

Results

The tissue types that can be identified in segmentation results include normal artery, artery with proximal stenosis, normal brain parenchyma, delayed‐perfusion brain parenchyma, vein and sinus, choroid plexus, cerebrospinal fluid, and leukoaraiosis. Concentration–time curves measured on normal and stenotic artery regions can be modeled as two arterial input functions. Unilateral carotid stenosis associated with either middle cerebral artery stenosis or poor collateral circulation at the circle of Willis resulted in increased differences of brain parenchyma TTP, T_max, and MTT between normal and stenotic sides.

Conclusion

Independent component analysis on perfusion images of patients with unilateral carotid stenosis provides useful spatiotemporal information regarding blood supply to arteries and local perfusion of brain parenchyma. J. Magn. Reson. Imaging 2008;28:1125–1132. © 2008 Wiley‐Liss, Inc.     

肾动脉狭窄的肾脏CT血流灌注参数研究

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36人,分为肾动脉狭窄组(24人)和对照组(12人),进行肾脏CT电影扫描获得动态序列图像,通过AW影像工作站计算肾脏皮质血流灌注参数,分析肾脏皮质血流灌注与肾动脉狭窄的关系。结果:肾动脉狭窄>75%组肾皮质单位体积血流量(BF)(189.9±102.3ml/100g/min)低于对照组(308.4±99.9ml/100g/min),有显著差异(P=0.026)。肾动脉狭窄50%-75%组及狭窄>75%组肾皮质微血管容积(BV)(24.6±7.6ml/100g,21.4±12.6ml/100g)低于对照组(41.1±14.1ml/100g),有非常显著差异(P=0.008,0.001)。各组之间平均通过时间(MTT)、毛细血管表面通透性(PS)无显著性差异(P>0.05)。结论:明显肾动脉狭窄的肾脏皮质BF、BV下降,CT血流灌注参数可以为评估肾动脉狭窄的肾脏是否缺血提供帮助。     

多层面螺旋CT对肝移植术后肝动脉狭窄肝灌注的研究

目的　利用动态单层CT扫描对原位肝移植术后肝动脉狭窄肝灌注与未行肝移植、无肝脏病变者进行比较。资料与方法　对 30例肝移植术后肝动脉狭窄患者选取肝门 (包括肝、门静脉、主动脉和脾 )层面行动态单层CT扫描。高压注射器经肘静脉注射非离子型对比剂欧乃派克 4 0ml,流率 3ml/s,注射对比剂时即进行扫描 ,每间隔1s扫 1层 ,共扫描 35层。通过每一层面选定的ROI作CT值测量 ,绘制出时间 密度曲线 ,从而计算出相应灌注值并与未行肝移植、无肝脏病变者进行对照。结果　肝移植术后肝动脉狭窄 <5 0 %组 ,肝动脉灌注 (t=0 .5 ,P >0 .0 5 )、门静脉灌注 (t=1 ,P >0 .0 5 )与对照组间无显著差异 ;肝动脉狭窄≥ 5 0 % ,肝动脉灌注与对照组存在差异 (t =2 .1 4 ,P <0 .0 5 ) ,低于对照组 ,门静脉灌注与对照组有差异 (t=2 .6 3,P <0 .0 5 ) ,高于对照组。结论　肝移植术后肝动脉狭窄≥ 5 0 % ,肝动脉灌注降低而门静脉灌注升高。动态单层CT扫描对于评价肝移植术后肝脏灌注是有帮助的     

基于CTA对肾动脉狭窄与肾动脉主干形态学特征的相关性分析

目的 研究肾动脉狭窄与肾动脉主干的形态学特征,特别是与肾动脉变异曲度的相关性。 方法 收集62例肾动脉狭窄的患者[男性37例、女性25例,年龄36~78（52.64±16.32）岁]进行肾动脉CT血管造影（CTA）,分别测量狭窄侧与非狭窄侧的肾动脉主干的平均管腔直径、管腔横截面积、长度、主干CT值、肾动脉主干强化CT值与腹主动脉强化CT值的比值（RA/AA）、肾皮质的平均强化CT值、最大曲度、肾动脉主干起点至最大曲度顶点的距离以及狭窄侧肾动脉主干起点至狭窄近端的距离。组间比较采用配对样本t检验。 结果 肾动脉狭窄62支,对侧肾动脉正常62支,伴有斑块形成的肾动脉狭窄侧,其肾动脉走行的最大曲度（0.15±0.02）明显大于非狭窄侧（0.08±0.02）,差异有统计学意义（t=19.487,P<0.05）,而狭窄侧与非狭窄侧的肾动脉主干的平均管腔直径、管腔横截面积、长度、肾动脉主干CT值、RA/AA、肾皮质的平均强化CT值分别为（5.39±0.53） mm、（20.52±7.22） mm2、（34.51±13.12） mm、 （349.54±51.23） HU、（94.25±3.46）%、（278.41±35.47） HU和（5.27±.062） mm、（18.97±5.05） mm2、 （35.27±14.74） mm、（353.31±54.37） HU、（93.46±3.62）%、（284.21±37.92） HU,二者比较差异均无统计学意义（t=1.158、1.385、0.303、0.397、1.242、0.879,均P>0.05）。狭窄侧与非狭窄侧肾动脉主干起点至最大曲度顶点的距离分别为（9.62±1.34） cm和（9.79±1.47） cm,差异无统计学意义（t=0.673,P>0.05）。狭窄侧肾动脉主干起点至狭窄近端的距离为（9.42±1.61） cm,与肾动脉起点至最大曲度顶点的距离[（9.62±1.34） cm]比较,差异无统计学意义（t=0.752,P>0.05）。 结论 CTA能够直接显示肾动脉水平的形态,其变异曲度与肾动脉狭窄有一定的相关性。     

Technetium-99m DTPA renal flow studies in Goldblatt hypertension

Computer-assisted dynamic renal studies were performed on a group of 14 mongrel dogs before and after the induction of unilateral renal artery stenosis. Ninety-second technetium-99m diethylenetriaminepentaacetic acid ( [99mTc]DTPA), 15-min [99mTc]DTPA, and 30-min iodine-131 orthoiodohippurate ( [131I]hippuran) time-activity curves were analyzed and correlated with reduction of renal blood flow as measured by electromagnetic flow probe and PAH clearance techniques. Parameters of the 90-sec [99mTc]DTPA curves found to be significantly different for the same kidney before and after stenosis were: upslope, curve width at 75% maximum, maximum activity value, and differential (stenotic/contralateral) maximum activity ratio. For blood flow reductions greater than 33%, the [99mTc]DTPA studies were judged diagnostic of unilateral renal artery stenosis in all cases, whereas the [131I]hippuran time-activity curves were indicative of stenosis in only six of ten studies. Thus, in this model we find the computer-assisted 90-sec [99mTc]DTPA renal flow study to be superior to conventional [131I]hippuran renography in the diagnosis of moderate-to-severe unilateral renal artery stenosis.     

利用灌注MRI技术评价颈内动脉狭窄或闭塞的血流动力学状态

目的 利用灌注磁共振成像(PWI)技术分析颈内动脉狭窄或闭塞时的血流动力学特点。资料与方法 搜集46例单侧颈内动脉狭窄或闭塞患者的资料，借助PWI对其血流动力学特点进行评价。结果 所有患者局部脑血流量没有显著性降低，但大脑中动脉分布区灌注明显延迟，在重度狭窄及闭塞时，分水岭区的灌注也出现障碍；不同的侧支循环代偿仅对大脑中动脉分布区的灌注有所影响，其中前交通动脉作用较为明显。结论 单侧颈内动脉狭窄时，PWI可以准确评价患者的血流动力学状况，而此时的血流动力学障碍与狭窄程度及侧支循环代偿均有明显的关系。     

Renal artery stenosis: in vivo perfusion MR imaging

The intravoxel incoherent motion (IVIM) model of perfusion and diffusion imaging was applied to an in vivo canine model of unilateral renal artery stenosis and was compared with relative renal blood flow determination with radioactive microspheres. The percentage relative renal blood flow as determined with radioactive microspheres correlated closely with the percentage apparent diffusion coefficient. If this method can be adapted to human imaging, it may provide a noninvasive means for detecting renal artery stenosis.     

多层螺旋CT脑灌注成像与血管成像联合评价颈动脉狭窄与脑梗死的临床研究

目的 应用多层螺旋CT灌注成像与CTA联合评价颈内动脉狭窄与脑梗塞的相关性.资料与方法 59例急性脑梗死患者,在急性发作后6 h内行CT灌注成像和CTA检查.通过CTA对颈动脉狭窄程度进行评估,通过灌注图像评估脑梗塞的血流动力学状态.结果 梗死侧颈动脉血管狭窄发生率显著高于非梗死侧(P＝0.001),颈动脉狭窄程度与脑梗死所致神经功能缺损的严重程度之间明显相关(P<0.05).结论 联合CT灌注与CTA能评价颈内动脉狭窄程度与脑组织的血流灌注情况之间的关系.     

Renal artery stenosis: CT angiography--comparison of real-time volume-rendering and maximum intensity projection algorithms

PURPOSE: To compare results of helical computed tomographic (CT) angiography with real-time interactive volume rendering (VR) to CT angiography with maximum intensity projection (MIP) for the detection of renal artery stenosis. MATERIALS AND METHODS: Twenty-five patients underwent both conventional and CT angiography of the renal arteries. Images were blindly reviewed after rendering with MIP and VR algorithms. MIP images were viewed in conjunction with axial CT images; VR models were evaluated in real time at the workstation without CT images. Findings in 50 main and 11 accessory renal arteries were categorized as normal or by degree of stenosis. RESULTS: All arteries depicted on conventional angiograms were visualized on MIP and VR images. Receiver operating characteristic (ROC) analysis for MIP and VIR images demonstrated excellent discrimination for the diagnosis of stenosis of at least 50% (area under the ROC curve, 0.96-0.99). Although sensitivity was not significantly different for VR and MIP (89% vs 94%, P > .1), specificity was greater with VR (99% vs 87%, P = .008 to .08). Stenosis of at least 50% was overestimated with CT angiography in four accessory renal arteries, but three accessory renal arteries not depicted at conventional angiography were depicted at CT angiography. CONCLUSION: In the evaluation of renal artery stenosis, CT angiography with VR is faster and more accurate than CT angiography with MIP. Accessory arteries not depicted with conventional angiography were depicted with both CT angiographic algorithms.     

Attenuation changes of the normal and ischemic canine kidney. Dynamic CT scanning after intravenous contrast medium bolus

The potential of CT scanning to explore total and regional renal blood flow was evaluated in a dog model with unilateral renal artery stenosis (n = 7, reduction of renal blood flow: 32-75% of base line flow). Attenuation versus time curves were generated for the renal cortex and medulla, as well as for the aorta and renal vein. A fast CT scanner was used which allowed for up to 24 scans/minute at the same level (slice thickness: 10 mm). A total of 10 ml contrast medium was injected into a peripheral vein for each scan series taken. During baseline conditions, the curve of the renal cortex and medulla demonstrated 2 peaks. The first peak was mainly related to early vascular enhancement, whereas the second peak corresponded mainly to the appearance of contrast medium in the distal convolutes and collecting ducts. Ischemia of the kidney resulted in a reduction of the first peak and a flattening of the leading edge slope. Transport of contrast medium through the extravascular compartments of the kidney was delayed during ischemia. Relative renal blood flow was obtained from the CT data by dividing peak enhancement by rise-time as assessed from the cortical curve. All measurements were related to baseline flow and validated by flow measurements using radioactive labeled microspheres (n = 5). Correlation was found to be r = 0.97.     

Evaluation of cerebral hemodynamics with computed tomography perfusion using gadolinium as an alternative to iodinated contrast: a case report

Computed tomography (CT) perfusion is traditionally performed using iodinated contrast, but this can be problematic in patients with impaired renal function or contrast allergy. We report a case of a 63-year-old man whose medical history was complicated by chronic renal failure, which was exacerbated after placement of a left cervical internal carotid artery stent by 70% stenosis and left hemisphere perfusion deficit. On a follow-up clinic visit, because of the patient s chronic renal failure, CT perfusion was performed successfully using gadolinium without further renal complications.     

Renal artery stenosis: functional assessment with dynamic MR perfusion measurements--feasibility study

PURPOSE: To prospectively assess feasibility of renal magnetic resonance (MR) perfusion measurement method based on turbo fast low-angle shot sequences for grading effect of renal artery stenosis (RAS) on parenchymal perfusion. MATERIALS AND METHODS: Institutional review board approved this study, and patients gave written consent. Seventy-three patients (34 male, 39 female; age range, 17-84 years) who were clinically suspected of having RAS underwent contrast material-enhanced (gadodiamide) saturation-recovery turbo fast low-angle shot imaging for measurement of renal perfusion and high-spatial-resolution MR angiography for RAS detection and grading. Degree of stenosis was evaluated as high grade (>/=75% stenosis), low to intermediate grade (>0% to <75% stenosis), or absent. High temporal resolution of the turbo fast low-angle shot sequence allowed acquisition of an exact first-pass tracing of the contrast agent bolus from which a signal intensity (SI)-time curve was derived. On the basis of this curve, mean transit time (MTT) of the contrast agent bolus, maximal upslope (MUS) of the curve, maximum SI, and time to SI peak (TTP) were calculated with a gamma variate fit. Wilcoxon rank sum test, Pearson product moment correlation, and paired t test were used for statistical analysis. RESULTS: Twenty-four renal arteries had high-grade RAS, 12 renal arteries had low- to intermediate-grade RAS, and 104 renal arteries had no RAS. Significant differences between patients without stenoses or with low- to intermediate-grade stenoses and patients with high-grade stenoses were found for MTT, MUS, and TTP (P < .001). Perfusion parameters were correlated with patients' serum creatinine levels, and significant correlations were found for MTT (r = 0.41), MUS (r = 0.48), and TTP (r = 0.4), with P < .001. CONCLUSION: MR perfusion parameters can be used to assess effect of RAS on parenchymal perfusion. Perfusion measurements reflect renal function as measured with serum creatinine levels.     

Quantification of renal perfusion abnormalities using an intravascular contrast agent (part 2): results in animals and humans with renal artery stenosis.

The interrelation between the morphologic degree of renal artery stenosis and changes in parenchymal perfusion is assessed using an intravascular contrast agent. In seven adult foxhounds, different degrees of renal artery stenosis were created with an inflatable clamp implanted around the renal artery. Dynamic susceptibility-weighted gradient-echo imaging was used to measure signal-time curves in the renal artery and the renal parenchyma during administration of 1.5 mg/kg BW of an intravascular ultrasmall particle iron oxide (USPIO) contrast agent. From the dynamic series, regional renal blood volume (rRBV), regional renal blood flow (rRBF), and mean transit time (MTT) were calculated. The morphologic degree of stenosis was measured in the steady state using a high-resolution 3D contrast-enhanced (CE) MR angiography (MRA) sequence (voxel size = 0.7 x 0.7 x 1 mm(3)). Five patients with renoparenchymal damage due to long-standing renal artery stenosis were evaluated. In the animal stenosis model, cortical perfusion remained unchanged for degrees of renal artery stenosis up to 80%. With degrees of stenoses > 80%, cortical perfusion dropped to 151 +/- 54 ml/100 g of tissue per minute as compared to a baseline of 513 +/- 76 ml/100 g/min. In the patients, a substantial difference in the cortical perfusion of more than 200 +/- 40 ml/100 g/min between the normal and the ischemic kidneys was found. The results show that quantitative renal perfusion measurements in combination with 3D-CE-MRA allow the functional significance of a renal artery stenosis to be determined in a single MR exam. Differentiation between renovascular and renoparenchymal disease thus becomes feasible.     

双源CT灌注成像在活体肝移植后对移植肝的评价作用

 目的 探讨双源CT灌注成像在活体肝移植后对移植肝的评价作用。方法 招募解放军总医院第三医学中心2013-06至2018-11进行活体肝移植术后1个月经超声及CTA检查肝动脉无狭窄患者25例;术后3个月患者61例,其中肝动脉无狭窄25例,轻度狭窄13例,中度狭窄12例,重度狭窄11例;同时收集同时期因怀疑有肝脏肿瘤行CT灌注扫描,后经临床及影像证实无肿瘤的患者(25例)作为对照组。上述所有研究对象均行双源CT全肝灌注成像检查并测量肝动脉灌注量(hepatic artery perfusion,HAP)、门静脉灌注量(portal vein perfusion, PVP)、肝总灌注量(total liver perfusion, TLP)及肝动脉灌注指数(hepatic perfusion index, HPI)。同时补充检测肝动脉狭窄人群的谷丙转氨酶(alanine transaminase, ALT)。结果 与对照组人群[(0.28±0.13) ml/(min·ml)]相比,肝移植术后1个月无肝动脉狭窄人群HAP[(0.36±0.17) ml/(min·ml)]显著增高(P<0.05),术后3个月中度及重度肝动脉狭窄人群HAP显著降低[(0.12±0.09)ml/(min·ml),(0.06±0.03) ml/(min·ml),P<0.05]。中度及重度肝动脉狭窄人群HPI较对照组显著降低(0.07±0.05、0.03±0.02 vs. 0.23±0.16, P<0.05)。重度肝动脉狭窄人群PVP较对照组显著升高[(1.81±0.36)ml/(min·ml) vs. (1.23±0.62) ml/(min·ml),P<0.05])。在肝动脉狭窄患者中,ALT对数与HAP对数成线性相关。结论 双源CT能对活体肝移植患者术后的移植肝进行血流灌注评价,能够为临床提供更为精准的信息,提高患者后续治疗的准确性。     

双源CT双能量心肌灌注对诊断心肌梗塞及其罪犯血管关系的研究

目的 探讨双源CT双能量心肌灌注对心肌梗塞的诊断价值及其与罪犯血管的关系.方法 用双源CT双能量灌注成像方法对42例临床疑诊或确诊为冠心病的患者进行扫描.分析心肌灌注情况与罪犯冠脉狭窄程度的关系;对19例临床确诊为陈旧性心梗患者的心电图与心肌灌注情况进行了对比分析.结果 42例患者的心肌灌注改变与冠脉狭窄程度存在线性变化趋势(P＞0.05),11例冠脉轻及中度狭窄患者心肌灌注未见异常,31例重度及完全闭塞患者,26例可见心肌灌注减低;19例临床确诊为陈旧性心梗患者心电图均见病理性Q波、心肌灌注均有缺损.结论 双源CT双能量心肌灌注成像.可一站式评价冠心病心肌缺血或梗死情况及其与罪犯血管的关系,对冠心病的诊断、治疗及预后评估具有重要指导意义.     

Quantitative coronary arterial stenosis assessment by multidetector CT and invasive coronary angiography for identifying patients with myocardial perfusion abnormalities

Background

Semi-quantitative stenosis assessment by coronary CT angiography only modestly predicts stress-induced myocardial perfusion abnormalities. The performance of quantitative CT angiography (QCTA) for identifying patients with myocardial perfusion defects remains unclear.

Methods

CorE-64 is a multicenter, international study to assess the accuracy of 64-slice QCTA for detecting ??50% coronary arterial stenoses by quantitative coronary angiography (QCA). Patients referred for cardiac catheterization with suspected or known coronary artery disease were enrolled. Area under the receiver-operating-characteristic curve (AUC) was used to evaluate the diagnostic accuracy of the most severe coronary artery stenosis in a subset of 63 patients assessed by QCTA and QCA for detecting myocardial perfusion abnormalities on exercise or pharmacologic stress SPECT.

Results

Diagnostic accuracy of QCTA for identifying patients with myocardial perfusion abnormalities by SPECT revealed an AUC of 0.71, compared to 0.72 by QCA (P?=?.75). AUC did not improve after excluding studies with fixed myocardial perfusion abnormalities and total coronary arterial occlusions. Optimal stenosis threshold for QCTA was 43% yielding a sensitivity of 0.81 and specificity of 0.50, respectively, compared to 0.75 and 0.69 by QCA at a threshold of 59%. Sensitivity and specificity of QCTA to identify patients with both obstructive lesions and myocardial perfusion defects were 0.94 and 0.77, respectively.

Conclusions

Coronary artery stenosis assessment by QCTA or QCA only modestly predicts the presence and the absence of myocardial perfusion abnormalities by SPECT. Confounding variables affecting the relationship between coronary anatomy and myocardial perfusion likely account for some of the observed discrepancies between coronary angiography and SPECT results.