正常大鼠脑CT灌注成像的可重复性研究

目的:评价多层螺旋CT灌注成像对正常大鼠脑血流动力学观测结果的可重复性.方法:分别对10只健康Wistar大鼠间隔2d进行CT灌注扫描,两组原始灌注数据由2名放射科医师分别进行5次后处理得出CBF、CBV和MTT值.分析观察者内和观察者间观测结果的可重复性,以及对同一组研究对象间隔2d两次检查结果的一致性.结果:多层螺旋CT对Wistar大鼠脑所采集的灌注原始数据在观察者内和观察者间观测结果均无统计学差别(P＞0.05),并具有很好的线性(CBF和CBV值)或等级(MTT值)正相关(P＜0.01).对同一组研究对象间隔2d的两次CT灌注成像结果也存在同样好的重复性.结论:多层螺旋CT灌注成像对于Wistar大鼠脑部血流动力学观测具有很高的精密度和准确性,完全适于小型动物模型脑部血流动力学的研究.     

正常大鼠脑血流动力学的CT灌注成像研究

目的:采用多层螺旋CT灌注成像探讨正常大鼠脑血流动力学特征.方法:对15只健康Wistar大鼠进行CT灌注扫描,定量测定全脑不同区域的血流动力学参数,分析正常Wistar大鼠脑血流动力学特征.结果:正常Wistar大鼠脑部不同区域的血流动力学参数存在较大差异(P＜0.05或0.01),Wistar大鼠的CBF和CBV值以小脑最高,其次是基底节区和延髓,大脑皮质的CBF和CBV值较低:而MTT值在Wistar大鼠脑部各区域比较接近,均值比较无统计学意义(P＞0.05).结论:多层螺旋CT可用于定量评价Wistar大鼠脑组织的血液动力学特征,完全适用于小型动物模型脑部血流动力学的研究.     

Comparison of Arterial Spin Labeling and Dynamic Susceptibility Contrast Perfusion MRI in Patients with Acute Stroke

Background

The aim of this study was to evaluate whether arterial spin labeling (ASL) perfusion magnetic resonance imaging (MRI) can reliably quantify perfusion deficit as compared to dynamic susceptibility contrast (DSC) perfusion MRI.

Methods

Thirty-nine patients with acute ischemic stroke in the anterior circulation territory were recruited. All underwent ASL and DSC MRI perfusion scans within 30 hours after stroke onset and 31 patients underwent follow-up MRI scans. ASL cerebral blood flow (CBF) and DSC time to maximum (T_max) maps were used to calculate the perfusion defects. The ASL CBF lesion volume was compared to the DSC T_max lesion volume by Pearson''s correlation coefficient and likewise the ASL CBF and DSC T_max lesion volumes were compared to the final infarct sizes respectively. A repeated measures analysis of variance and least significant difference post hoc test was used to compare the mean lesion volumes among ASL CBF, DSC T_max >4–6 s and final infarct.

Results

Mean patient age was 72.6 years. The average time from stroke onset to MRI was 13.9 hours. The ASL lesion volume showed significant correlation with the DSC lesion volume for T_max >4, 5 and 6 s (r = 0.81, 0.82 and 0.80; p<0.001). However, the mean lesion volume of ASL (50.1 ml) was significantly larger than those for T_max >5 s (29.2 ml, p<0.01) and T_max >6 s (21.8 ml, p<0.001), while the mean lesion volumes for T_max >5 or 6 s were close to mean final infarct size.

Conclusion

Quantitative measurement of ASL perfusion is well correlated with DSC perfusion. However, ASL perfusion may overestimate the perfusion defects and therefore further refinement of the true penumbra threshold and improved ASL technique are necessary before applying ASL in therapeutic trials.     

抑郁症患者的脑CT灌注成像特征与认知功能的相关性

摘要 目的：探讨抑郁症患者的脑CT灌注成像特征与认知功能的相关性。方法：选取我院2020年1月到2023年1月收治的90例抑郁症患者作为研究对象,将其分为观察组,另选取同期来我院体检的90名健康志愿者作为对照组。收集所有受检者脑CT灌注成像检查数据,分析抑郁症患者的脑CT灌注成像特征,并建立受试者工作特征（ROC）曲线分析脑CT灌注成像对抑郁症的诊断效能。随后对观察组和对照组受检者均进行认知功能评估,其中包括连线检测（TMT）、视觉再生测验（VRT）、言语流畅性测验（VF）、数字广度测验（DST）以及数字符号测验（SDMT）,并分析脑CT灌注成像与抑郁症认知功能的相关性。结果：观察组与对照组受检者rCBV、rCBF、MTT、TIP、右枕叶、左枕叶、右颞叶、左颞叶、右顶叶、左顶叶CT值对比无明显差异（P＞0.05）,观察组与对照组受检者右额叶、左额叶CT值对比差异显著,观察组明显低于对照组（P＜0.05）;90例抑郁症患者经过汉密尔顿抑郁量表（HAMD）评估后分数均＞20分,确定存在抑郁症状,脑CT灌注成像与HAMD评分诊断抑郁症的准确性、灵敏度、特异性、阳性预测值和阴性预测值对比无明显差异（P＞0.05）,脑CT灌注成像的曲线下面积为83.89,最佳诊断着色界限值为82.53%,HAMD评分的曲线下面积为84.26,最佳诊断着色界限值为87.57%;观察组与对照组受检者连线提笔数、连线错误数、视觉再生检测结果对比无明显差异（P＞0.05）,观察组与对照组受检者连线、言语流畅性、数字广度、数字符号检测结果对比差异显著（P＜0.05）;Spearman相关分析结果表明：连线提笔数、连线错误数、视觉再生与脑CT灌注参数均无明显相关性（P＞0.05）,连线、言语流畅性、数字广度、数字符号与rCBV、rCBF、MTT、TIP、右枕叶、左枕叶、右颞叶、左颞叶、右顶叶、左顶叶CT值无明显相关性（P＞0.05）,连线与右额叶、左额叶CT值呈负相关（P＜0.05）,言语流畅性、数字广度、数字符号与右额叶、左额叶CT值呈正相关（P＜0.05）。结论：抑郁症患者的脑CT灌注成像与健康群体呈现差异,其中右额叶、左额叶差异情况最为显著,提示抑郁症患者可能存在大脑额叶功能改变,另外,抑郁症患者的大脑额叶功能与认知功能变化具有明显相关性。     

Dual Energy CT Angiography of Peripheral Arterial Disease: Feasibility of Using Lower Contrast Medium Volume

ObjectiveOne of the main drawbacks associated with Dual Energy Computed Tomography Angiography (DECTA) is the risk of developing contrast medium-induced nephropathy (CIN). The aim of the present study was firstly, to design an optimal CT imaging protocol by determining the feasibility of using a reduced contrast medium volume in peripheral arterial DECTA, and secondly, to compare the results with those obtained from using routine contrast medium volume.MethodsThirty four patients underwent DECTA for the diagnosis of peripheral arterial disease. They were randomly divided into two groups: Group 1 (routine contrast volume group) with n = 17, injection rate 4–5 ml/s, and 1.5 ml/kg of contrast medium, and Group 2 ((low contrast volume group), with n = 17, injection rate 4–5ml/s, and contrast medium volume 0.75 ml/kg. A fast kilovoltage—switching 64-slice CT scanner in the dual-energy mode was employed for the study. A total of 6 datasets of monochromatic images at 50, 55, 60, 65, 70 and 75 keV levels were reconstructed with adaptive statistical iterative reconstruction (ASIR) at 50%. A 4-point scale was the tool for qualitative analysis of results. The two groups were compared and assessed quantitatively for image quality on the basis of signal-to-noise ratio (SNR) and contrast-to-noise-ratio (CNR). Radiation and contrast medium doses were also compared.ResultsThe overall mean CT attenuation and mean noise for all lower extremity body parts was significantly lower for the low volume contrast group (p<0.001), and varied significantly between groups (p = 0.001), body parts (p<0.001) and keVs (p<0.001). The interaction between group body parts was significant with CT attenuation and CNR (p = 0.002 and 0.003 respectively), and marginally significant with SNR (p = 0.047), with minimal changes noticed between the two groups. Group 2 (low contrast volume group) displayed the lowest image noise between 65 and 70 keV, recorded the highest SNR and CNR at 65 keV, and produced significantly lower results with respect to contrast medium volume and duration of contrast injection (p<0.001). The effect of radiation dose was not statistically significant between the two groups.ConclusionsDECTA images created at 65 keV and 50% ASIR with low contrast medium volume protocol, yielded results that were comparable to routine contrast medium volume, with acceptable diagnostic images produced during the evaluation of peripheral arteries.     

Intra-Arterial MR Perfusion Imaging of Meningiomas: Comparison to Digital Subtraction Angiography and Intravenous MR Perfusion Imaging

MethodsStudies were performed in a suite comprised of an x-ray angiography unit and 1.5T MR scanner that permitted intraprocedural patient movement between the imaging modalities. Patients underwent intra-arterial (IA) and intravenous (IV) T2* dynamic susceptibility MR perfusion immediately prior to meningioma embolization. Regional tumor arterial supply was characterized by digital subtraction angiography and classified as external carotid artery (ECA) dural, internal carotid artery (ICA) dural, or pial. MR perfusion data regions of interest (ROIs) were analyzed in regions with different vascular supply to extract peak height, full-width at half-maximum (FWHM), relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), and mean transit time (MTT). Linear mixed modeling was used to identify perfusion curve parameter differences for each ROI for IA and IV MR imaging techniques. IA vs. IV perfusion parameters were also directly compared for each ROI using linear mixed modeling.Results18 ROIs were analyzed in 12 patients. Arterial supply was identified as ECA dural (n = 11), ICA dural (n = 4), or pial (n = 3). FWHM, rCBV, and rCBF showed statistically significant differences between ROIs for IA MR perfusion. Peak Height and FWHM showed statistically significant differences between ROIs for IV MR perfusion. RCBV and MTT were significantly lower for IA perfusion in the Dural ECA compared to IV perfusion. Relative CBF in IA MR was found to be significantly higher in the Dural ICA region and MTT significantly lower compared to IV perfusion.     

Penumbra Pattern Assessment in Acute Stroke Patients: Comparison of Quantitative and Non-Quantitative Methods in Whole Brain CT Perfusion

Background And Purpose

While penumbra assessment has become an important part of the clinical decision making for acute stroke patients, there is a lack of studies measuring the reliability and reproducibility of defined assessment techniques in the clinical setting. Our aim was to determine reliability and reproducibility of different types of three-dimensional penumbra assessment methods in stroke patients who underwent whole brain CT perfusion imaging (WB-CTP).

Materials And Methods

We included 29 patients with a confirmed MCA infarction who underwent initial WB-CTP with a scan coverage of 100 mm in the z-axis. Two blinded and experienced readers assessed the flow-volume-mismatch twice and in two quantitative ways: Performing a volumetric mismatch analysis using OsiriX imaging software (MM_VOL) and visual estimation of mismatch (MM_EST). Complementarily, the semiquantitative Alberta Stroke Programme Early CT Score for CT perfusion was used to define mismatch (MM_ASPECTS). A favorable penumbral pattern was defined by a mismatch of ≥30% in combination with a cerebral blood flow deficit of ≤90 ml and an MM_ASPECTS score of ≥1, respectively. Inter- and intrareader agreement was determined by Kappa-values and ICCs.

Results

Overall, MM_VOL showed considerably higher inter-/intrareader agreement (ICCs: 0.751/0.843) compared to MM_EST (0.292/0.749). In the subgroup of large (≥50 mL) perfusion deficits, inter- and intrareader agreement of MM_VOL was excellent (ICCs: 0.961/0.942), while MM_EST interreader agreement was poor (0.415) and intrareader agreement was good (0.919). With respect to penumbra classification, MM_VOL showed the highest agreement (interreader agreement: 25 agreements/4 non-agreements/κ: 0.595; intrareader agreement 27/2/0.833), followed by MM_EST (22/7/0.471; 23/6/0.577), and MM_ASPECTS (18/11/0.133; 21/8/0.340).

Conclusion

The evaluated approach of volumetric mismatch assessment is superior to pure visual and ASPECTS penumbra pattern assessment in WB-CTP and helps to precisely judge the extent of 3-dimensional mismatch in acute stroke patients.     

Influence of Thin Slice Reconstruction on CT Brain Perfusion Analysis

Objectives

Although CT scanners generally allow dynamic acquisition of thin slices (1 mm), thick slice (≥5 mm) reconstruction is commonly used for stroke imaging to reduce data, processing time, and noise level. Thin slice CT perfusion (CTP) reconstruction may suffer less from partial volume effects, and thus yield more accurate quantitative results with increased resolution. Before thin slice protocols are to be introduced clinically, it needs to be ensured that this does not affect overall CTP constancy. We studied the influence of thin slice reconstruction on average perfusion values by comparing it with standard thick slice reconstruction.

Materials and Methods

From 50 patient studies, absolute and relative hemisphere averaged estimates of cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), and permeability-surface area product (PS) were analyzed using 0.8, 2.4, 4.8, and 9.6 mm slice reconstructions. Specifically, the influence of Gaussian and bilateral filtering, the arterial input function (AIF), and motion correction on the perfusion values was investigated.

Results

Bilateral filtering gave noise levels comparable to isotropic Gaussian filtering, with less partial volume effects. Absolute CBF, CBV and PS were 22%, 14% and 46% lower with 0.8 mm than with 4.8 mm slices. If the AIF and motion correction were based on thin slices prior to reconstruction of thicker slices, these differences reduced to 3%, 4% and 3%. The effect of slice thickness on relative values was very small.

Conclusions

This study shows that thin slice reconstruction for CTP with unaltered acquisition protocol gives relative perfusion values without clinically relevant bias. It does however affect absolute perfusion values, of which CBF and CBV are most sensitive. Partial volume effects in large arteries and veins lead to overestimation of these values. The effects of reconstruction slice thickness should be taken into account when absolute perfusion values are used for clinical decision making.     

Magnetic Resonance Imaging Quantification of Pulmonary Perfusion using Calibrated Arterial Spin Labeling

This demonstrates a MR imaging method to measure the spatial distribution of pulmonary blood flow in healthy subjects during normoxia (inspired O₂, fraction (F_IO₂) = 0.21) hypoxia (F_IO₂ = 0.125), and hyperoxia (F_IO₂ = 1.00). In addition, the physiological responses of the subject are monitored in the MR scan environment. MR images were obtained on a 1.5 T GE MRI scanner during a breath hold from a sagittal slice in the right lung at functional residual capacity. An arterial spin labeling sequence (ASL-FAIRER) was used to measure the spatial distribution of pulmonary blood flow ^1,2 and a multi-echo fast gradient echo (mGRE) sequence ³ was used to quantify the regional proton (i.e. H₂O) density, allowing the quantification of density-normalized perfusion for each voxel (milliliters blood per minute per gram lung tissue). With a pneumatic switching valve and facemask equipped with a 2-way non-rebreathing valve, different oxygen concentrations were introduced to the subject in the MR scanner through the inspired gas tubing. A metabolic cart collected expiratory gas via expiratory tubing. Mixed expiratory O₂ and CO₂ concentrations, oxygen consumption, carbon dioxide production, respiratory exchange ratio, respiratory frequency and tidal volume were measured. Heart rate and oxygen saturation were monitored using pulse-oximetry. Data obtained from a normal subject showed that, as expected, heart rate was higher in hypoxia (60 bpm) than during normoxia (51) or hyperoxia (50) and the arterial oxygen saturation (SpO₂) was reduced during hypoxia to 86%. Mean ventilation was 8.31 L/min BTPS during hypoxia, 7.04 L/min during normoxia, and 6.64 L/min during hyperoxia. Tidal volume was 0.76 L during hypoxia, 0.69 L during normoxia, and 0.67 L during hyperoxia. Representative quantified ASL data showed that the mean density normalized perfusion was 8.86 ml/min/g during hypoxia, 8.26 ml/min/g during normoxia and 8.46 ml/min/g during hyperoxia, respectively. In this subject, the relative dispersion⁴, an index of global heterogeneity, was increased in hypoxia (1.07 during hypoxia, 0.85 during normoxia, and 0.87 during hyperoxia) while the fractal dimension (Ds), another index of heterogeneity reflecting vascular branching structure, was unchanged (1.24 during hypoxia, 1.26 during normoxia, and 1.26 during hyperoxia). Overview. This protocol will demonstrate the acquisition of data to measure the distribution of pulmonary perfusion noninvasively under conditions of normoxia, hypoxia, and hyperoxia using a magnetic resonance imaging technique known as arterial spin labeling (ASL). Rationale: Measurement of pulmonary blood flow and lung proton density using MR technique offers high spatial resolution images which can be quantified and the ability to perform repeated measurements under several different physiological conditions. In human studies, PET, SPECT, and CT are commonly used as the alternative techniques. However, these techniques involve exposure to ionizing radiation, and thus are not suitable for repeated measurements in human subjects.Download video file.^{(74M, mov)}     

Differentiation of Brain Abscesses from Glioblastomas and Metastatic Brain Tumors: Comparisons of Diagnostic Performance of Dynamic Susceptibility Contrast-Enhanced Perfusion MR Imaging before and after Mathematic Contrast Leakage Correction

Purpose

To compare the diagnostic performance of dynamic susceptibility contrast-enhanced perfusion MRI before and after mathematic contrast leakage correction in differentiating pyogenic brain abscesses from glioblastomas and/or metastatic brain tumors.

Materials and Methods

Cerebral blood volume (CBV), leakage-corrected CBV and leakage coefficient K₂ were measured in enhancing rims, perifocal edema and contralateral normal appearing white matter (NAWM) of 17 abscesses, 19 glioblastomas and 20 metastases, respectively. The CBV and corrected CBV were normalized by dividing the values in the enhancing rims or edema to those of contralateral NAWM. For each study group, a paired t test was used to compare the K₂ of the enhancing rims or edema with those of NAWM, as well as between CBV and corrected CBV of the enhancing rims or edema. ANOVA was used to compare CBV, corrected CBV and K₂ among three lesion types. The diagnostic performance of CBV and corrected CBV was assessed with receiver operating characteristic (ROC) curve analysis.

Results

The CBV and correction CBV of enhancing rim were 1.45±1.17 and 1.97±1.01 for abscesses, 3.85±2.19 and 4.39±2.33 for glioblastomas, and 2.39±0.90 and 2.97±0.78 for metastases, respectively. The CBV and corrected CBV in the enhancing rim of abscesses were significantly lower than those of glioblastomas and metastases (P = 0.001 and P = 0.007, respectively). In differentiating abscesses from glioblastomas and metastases, the AUC values of corrected CBV (0.822) were slightly higher than those of CBV (0.792).

Conclusions

Mathematic leakage correction slightly increases the diagnostic performance of CBV in differentiating pyogenic abscesses from necrotic glioblastomas and cystic metastases. Clinically, DSC perfusion MRI may not need mathematic leakage correction in differentiating abscesses from glioblastomas and/or metastases.     

激光散斑成像技术在脑科学研究中的应用

激光散斑衬比成像(laser speckle contrast imaging,LSCI)是一种非扫描式实时血流动力学成像技术,具有高分辨率、快速实时成像、非接触、仪器结构较简单等优势.尽管由于深度分辨率的限制,LSCI主要用于浅表组织测量,但其在神经疾病、皮肤病等领域的基础研究及临床应用中展现出良好的应用潜力.本文简要介绍了激光散斑衬比成像技术的基本原理与技术进展,综述其在脑卒中、吸毒成瘾、阿尔茨海默病等脑疾病及其他脑科学应用中的研究进展,并展望其发展前景.     

CT灌注评价高碳酸血症模型下正常大鼠脑组织血流动力学变化

目的探讨CT灌注评价高碳酸血症模型下正常大鼠脑组织血流动力学变化的可行性;研究大鼠CT灌注参数变化率与α-SMA表达之间的相关性。方法 10只雄性SD大鼠,体质量250～300g,在吸入空气和吸入高浓度CO2混合气体(10%CO2和90%空气组成)后15min,分别使用GE16层Light Speed CT扫描仪对大鼠脑尾状核层面进行CT灌注扫描,原始图像经GE ADW4.2工作站Perfusion3.0脑部灌注软件处理后产生灌注曲线及伪彩图像,两次扫描前均测定大鼠的血液CO2分压、pH值等血气分析指标。检查结束后24h内,大鼠取脑固定,在尾状核中心层面切片,进行脑组织HE染色及鼠特异性SMA抗体免疫组化染色。应用SPSS11.5统计学软件进行分析:采用配对t检验,比较正常大鼠右侧尾状核在吸入空气和吸入高浓度CO2混合气体后CT灌注参数脑血容量(CBV)、脑血流量(CBF)、血管表面通透性(PS)和平均透过时间(MTT)的变化有无差异;采用Pearson相关分析分别检测大鼠右侧尾状核的SMA阳性血管染色计数与灌注参数CBV和CBF在CO2分压升高前后的变化率相关性。结果所有大鼠在吸入含10%CO2和90%空气的混合气体15min后,动脉血CO2分压均明显升高(t=9.39,P0.001),血浆pH值降低(t=13.49,P0.001)。正常SD大鼠右侧基底节区CBV、CBF、PS每100g组织分别为(10.28±4.01)mL、(304.95±88.77)mL/min、(0.26±0.37)mL/min,MTT值为(1.48±0.07)s;吸入10%CO2和90%空气的混合气体后右侧基底节区CBV、CBF值明显增加,每100g组织分别为(19.25±8.42)mL(t=4.92,P=0.001)和(507.33±167.94)mL/min(t=6.75,P0.001);吸入混合气体前后CBV、CBF增加百分比分别为(87.14±46.45)%、(65.75±22.05)%;PS及MTT变化不显著(P均0.05)。大鼠脑组织α-SMA阳性染色血管计数为(12.7±3.23)条/高倍视野。Pearson相关分析显示,正常脑组织的CBV和CBF变化率与其α-SMA阳性计数之间呈显著相关(r分别为0.652和0.890,P均0.05)。结论 CT灌注技术在改变血液CO2分压的条件下可以反映脑组织血流动力学变化;大鼠正常脑组织高碳酸血症前后CT灌注参数变化率与成熟血管数量相关。     

正常小型家猪脑血流灌注特征的SPECT/CT研究

目的:探讨采用SPECT/CT获得小型家猪脑血流灌注特征的方法和可行性.方法:对8头健康小型家猪进行SPECT/CT脑显像,进行图像预处理,自动提取脑相同感兴趣的相对血流量和相对离散度.结果:正常小猪脑不同感兴趣区相对血流量存在较大差异(P<0.05),相对脑血流量值以颞顶叶最高,其次是额顶叶,小脑最低.正常小猪脑各感兴趣内的相对离散度有统计学差异(P<0.05),相对离散度小脑感兴趣区最高,额叶感兴趣区最低.结论:SPECT/CT可用于半定量评价小型家猪脑血流灌注.     

SPECT 对症状性颅内动脉狭窄支架成形术的疗效评价

目的:通过SPECT脑血流灌注显像,对症状性颅内动脉粥样硬化性狭窄行颅内支架成形术,进行血流动力学的疗效评价。方法:对42例症状性颅内动脉粥样硬化性狭窄(狭窄程度>50%)患者,术前通过SPECT,分为低灌注组和正常灌注组。术后3月复查SPECT,做出血流动力学的疗效评价。通过术前及术后1年mRS评分,比较两组的远期疗效。结果:低灌注组发病症状一般为缺血性卒中,正常灌注组一般为TIA(P<0.01)。低灌注组术后血流灌注较术前改善明显(P<0.01)。正常灌注组复发性TIA的发生率较低灌注组高(P<0.05)。低灌注组术前术后mRS评分有统计学差异(P<0.05)。结论:颅内支架成形术可以明确改善颅内低灌注区的血流灌注,对低灌注组术后缺血事件的预防效果好,并有改善神经功能作用。因此,存在颅内低灌注区的患者更具有颅内支架成形术的手术适应症。     

两种碘浓度对比剂对肾脏CT增强扫描的对比研究

目的：对比300 mgI.ml-1对比剂与400 mgI.ml-1对比剂对肾脏多层面CT（multislice CT,MSCT）多期增强扫描的强化作用及不良反应。材料与方法：68例腹部CT受检者随机分成两组各34例,分别给予肾脏平扫和典比乐300（300 mgI.ml-1）与碘迈伦400（400 mgI.ml-1）的多期增强MSCT扫描（在对比剂开始注射后18s、30 s、80 s、3 min~5 min）,测量各期增强扫描腹主动脉、双肾动脉、双肾静脉、双肾皮质、双肾髓质、双肾盂的CT强化值。观察对比剂的不良反应。结果：使用400 mgI.ml-1对比剂在18s与30s采集,所检测的血管与肾各结构强化均值有意义高于300 mgI.ml-1对比剂（p〈0.01）,80 s采集,肾动脉、肾静脉、肾髓质强化均值有意义高于300 mgI.ml-1对比剂（p〈0.01）,3 min~5 min采集,肾静脉与肾盂强化均值有意义高于300 mgI.ml-1对比剂（p〈0.01）。结论：高碘浓度对比剂对肾脏各解剖结构的显示优于标准碘浓度对比剂,并可降低对比剂用量,而不良反应并无增加。     

Application of 128 Slice 4D CT Whole Liver Perfusion Imaging in Hepatic Tumor

To investigate the clinical significance of 128 slice whole liver four dimensional computed tomography (4D CT) in diagnosis and differential diagnosis of hepatic disease, by characterizing and comparing perfusion maps in two common hepatic tumors: hepatocellular carcinoma (HCC) and liver hemangioma. 45 patients with HCC and 40 patients with liver hemangioma were subjected to 128 slice 4D CT of the whole liver perfusion scan, perfusion images were obtained, and data were processed by the perfusion software. Four perfusion parameters generated automatically were used to characterize and compare the perfusion of tumor tissue and surrounding hepatic parenchyma: blood flow perfusion (BF), arterial liver perfusion (ALP), portal venous perfusion (PVP), and hepatic perfusion index (HPI). Volumetric CT perfusion data then reconstructed to yield 4D CT angiography. Morphological observation was made regarding to the blood supply of tumor, intrahepatic vasculature. (1) In both HCC and hepatic hemangioma, BF, ALP, HPI were higher (P < 0.01), whereas PVP were lower (P < 0.01) in tumor tissue than the surrounding hepatic parenchyma (within 1 cm of lesion). Compared with liver hemangioma tumor tissue, BF, ALP, PVP were lower in HCC tumor tissue (P < 0.05; 0.01; 0.01), but HPI is higher (P < 0.05). For the perfusion of the surrounding parenchyma, BF and ALP were higher (P < 0.001), PVP was lower (P < 0.001) in HCC, while HPI was unchanged. (2) Among 45 cases with HCC, cancer feeding artery was found in 28 cases. In 20 cases feeding artery was shown as thickening, rigid, or distorted. Tumor thrombus in portal vein was found in 14 cases. For total of 40 cases with liver hemangioma, in 23 cases blood vessels are shifted due to compression from tumor mass, the rest 17 cases show normal vasculature. With application of 128 slice 4D CT, whole liver perfusion scan can reliably reflect the hemodynamic characteristics of HCC and hepatic hemangioma, proving to be a valuable adjunct to conventional imaging techniques of liver for early detection, differential diagnosis, and determining surgical resection range as well as estimating prognosis for hepatic tumors.     

肝CT灌注成像技术在肝脏肿瘤应用现状、存在的问题及展望

CT灌注成像(CT perfusion imaging,CTPI)作为一种功能成像技术可无创性评估靶目标的血流动力学情况。自1993年Mile等首次报道其在肝脏肿瘤的应用以来,随着工业技术的进步,软硬件的更新,既往CTPI存在的问题,诸如,辐射剂量过高,扫描协议缺乏标准化,呼吸运动伪影,结果可重复性问题,扫描范围较小等问题均得到了不同程度的改善,使其在肝脏肿瘤应用中表现出了巨大的潜力。众所周知,CTPI的出现弥补了传统形态学成像方式对肿瘤的早期诊断,预后评估,检测新型分子靶向药物疗效等的不足。本文总结了近年来肝CTPI技术在肝肿瘤应用现状、存在的问题及未来展望。