CT灌注成像技术用于重型颅脑损伤患者脑室型颅内压探头植入的临床价值评估

目的:探讨CT灌注成像技术用于重型颅脑损伤患者脑室型颅内压(Intracranial Pressure, ICP)探头植入的临床价值。方法:选取60例重型颅脑损伤患者,均行患侧开颅去骨瓣减压和颅内压监测探头置入术。其中,行普通型颅内压监测探头置入术28例,脑室型颅内压监测探头置入术32例。比较两组术后甘露醇应用剂量和应用时间,术后局部脑血流参数区域脑血流量(regional Cerebral Blood Flow, r CBF)、相对脑血容量(relative Cerebral Blood Volume, r CBV)、平均通过时间(Mean Transit Time, MTT)、对比剂达峰时间(time to peak, TTP)恢复情况。结果:脑室型颅内压监测组患者术后应用甘露醇的剂量和天数较普通颅内压监测组明显缩短(P0.05),术后3个月随访提示脑室型ICP监测组预后良好比例较普通型ICP组显著增加(P0.05)。并且螺旋CT灌注成像结果提示脑室型颅内压监测组患者术后局部脑血流参数r CBF、r CBV、MTT、TTP恢复情况明显优于普通型颅内压监测组(P0.05)。结论:重型颅脑损伤患者应用脑室型颅内监测探头改变了脱水剂在临床应用中的治疗模式,通过螺旋CT灌注成像检测患者损伤部位的r CBF、r CBV、MTT和TTP可评估脑损伤的程度以及预后,对重型颅脑损伤的临床治疗和改善患者预后具有重要意义。     

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。     

MR扩散加权成像和CT及MR灌注成像对不同程度肝硬化患者的诊断价值

目的:研究MR扩散加权成像(DWI)和CT及MR灌注成像对不同程度肝硬化患者的诊断价值。方法:选择从2015年8月到2017年2月在我院治疗的肝硬化患者60例作为研究对象,根据Child-Pugh分级进行分组,其中A级32例为轻度肝硬化(记为A组),B级16例、C级12例为中重度肝硬化(记为B组),另选同期在我院进行体检的健康志愿者30例记为C组,对三组受试者分别进行DWI检查、CT及MR灌注成像,对比各组ADC值、肝脏动门脉灌注比率[SSr(ct)及SSr(mr)],采用Spearman相关性分析各指标之间的相关性。结果:三组ADC值整体比较无统计学差异(P0.05),A、B两组的ADC值较C组降低,但差异无统计学意义(P0.05)。A、B两组的ADC值比较无统计学差异(P0.05)。三组SSr(ct)、SSr(mr)整体比较,差异有统计学意义(P0.05),B组的SSr(ct)及SSr(mr)较A、C两组明显升高,差异均有统计学意义(均P0.05)。A、C两组的SSr(ct)及SSr(mr)比较无统计学差异(P0.05)。Spearman相关性分析显示,不同程度肝硬化患者的SSr(ct)与SSr(mr)呈正相关(r=0.687,P=0.000)。结论:CT以及MR灌注成像均可较好地反映出肝硬化的病变程度,且二者较DWI成像的诊断效果更佳,值得临床推广。     

The role of perfusion computed tomography in the prediction of cerebral hyperperfusion syndrome

Background

Hyperperfusion syndrome (HPS) following carotid angioplasty with stenting (CAS) is associated with significant morbidity and mortality. At present, there are no reliable parameters to predict HPS. The aim of this study was to clarify whether perfusion computed tomography (CT) is a feasible and reliable tool in predicting HPS after CAS.

Methodology/Principal Findings

We performed a retrospective case-control study of 54 patients (11 HPS patients and 43 non-HPS) with unilateral severe stenosis of the carotid artery who underwent CAS. We compared the prevalence of vascular risk factors and perfusion CT parameters including regional cerebral blood volume (rCBV), regional cerebral blood flow (rCBF), and time to peak (TTP) within seven days prior to CAS. Demographic information, risk factors for atherosclerosis, and perfusion CT parameters were evaluated by multivariable logistic regression analysis. The rCBV index was calculated as [(ipsilateral rCBV - contralateral rCBV)/contralateral rCBV], and indices of rCBF and TTP were similarly calculated. We found that eleven patients had HPS, including five with intracranial hemorrhages (ICHs) of whom three died. After a comparison with non-HPS control subjects, independent predictors of HPS included the severity of ipsilateral carotid artery stenosis, 3-hour mean systolic blood pressure (3 h SBP) after CAS, pre-stenting rCBV index >0.15 and TTP index >0.22.

Conclusions/Significance

The combination of severe ipsilateral carotid stenosis, 3 h SBP after CAS, rCBV index and TTP index provides a potential screening tool for predicting HPS in patients with unilateral carotid stenosis receiving CAS. In addition, adequate management of post-stenting blood pressure is the most important treatable factor in preventing HPS in these high risk patients.     

Multiparametric Characterization of Grade 2 Glioma Subtypes Using Magnetic Resonance Spectroscopic,Perfusion, and Diffusion Imaging

BACKGROUND AND PURPOSE: The purpose of this study was to derive quantitative parameters from magnetic resonance (MR) spectroscopic, perfusion, and diffusion imaging of grade 2 gliomas according to the World Health Organization and to investigate how these multiple imaging modalities can contribute to evaluating their histologic subtypes and spatial characteristics. MATERIALS AND METHODS: MR spectroscopic, perfusion, and diffusion images from 56 patients with newly diagnosed grade 2 glioma (24 oligodendrogliomas, 18 astrocytomas, and 14 oligoastrocytomas) were retrospectively studied. Metabolite intensities, relative cerebral blood volume (rCBV), and apparent diffusion coefficient (ADC) were statistically evaluated. RESULTS: The 75th percentile rCBV and median ADC were significantly different between oligodendrogliomas and astrocytomas (P < .0001) and between oligodendrogliomas and oligoastrocytomas (P < .001). Logistic regression analysis identified both 75th percentile rCBV and median ADC as significant variables in the differentiation of oligodendrogliomas from astrocytomas and oligoastrocytomas. Group differences in metabolite intensities were not significant, but there was a much larger variation in the volumes and maximum values of metabolic abnormalities for patients with oligodendroglioma compared with the other tumor subtypes. CONCLUSIONS: Perfusion and diffusion imaging provide quantitative MR parameters that can help to differentiate grade 2 oligodendrogliomas from grade 2 astrocytomas and oligoastrocytomas. The large variations in the magnitude and spatial extent of the metabolic lesions between patients and the fact that their values are not correlated with the other imaging parameters indicate that MR spectroscopic imaging may provide complementary information that is helpful in targeting therapy, evaluating residual disease, and assessing response to therapy.     

Cerebral perfusion changes in patients with internal carotid artery stenoses after surgical revascularization

Changes of cerebral perfusion and the condition of collateral blood supply in patients with internal carotid artery stenoses may have a prognostic value for effective blood flow restoration after revascularization of the internal carotid arteries (ICAs). To determine the patterns of cerebral perfusion changes in patients with ICA stenoses before and after surgical treatment, a clinical CT perfusion study of 41 patients with moderate to severe ICA stenoses was performed. Perfusion CT (PCT) had been conducted in 17 patients with moderate ICA stenoses (50–69%) and in 24 patients with severe ICA stenoses (70–99%) 3 times: before intervention (balloon angioplasty with stenting or carotid endarterectomy), on the 3rd to 7th day, and within 1 to 3 months after surgery. Scanning was performed at the level of the basal ganglia and semioval centers. In patients without ICA stenosis (control group of 39 individuals), PCT was conducted once. We found that surgical recanalization of the ICA leads to normalization of the cerebral blood flow parameters in the perfusion area of the middle cranial artery, as evidenced by a decrease of MTT and CBV and an increase of CBF to values comparable to those in the control group. However, blood flow restoration in the anterior and posterior watershed areas, which are known to be mostly affected under chronic hypoperfusion conditions, was observed only in patients with a complete circle of Willis (CW) and moderate ICA stenosis. Therefore, severe stenosis (>70%) and the incomplete CW are the prognostic factors for inadequate blood flow restoration after revascularization in patients with ICA stenoses.     

The Role of Dynamic Susceptibility Contrast-Enhanced Perfusion MR Imaging in Differentiating between Infectious and Neoplastic Focal Brain Lesions: Results from a Cohort of 100 Consecutive Patients

Background and Purpose

Differentiating between infectious and neoplastic focal brain lesions that are detected by conventional structural magnetic resonance imaging (MRI) may be a challenge in routine practice. Brain perfusion-weighted MRI (PWI) may be employed as a complementary non-invasive tool, providing relevant data on hemodynamic parameters, such as the degree of angiogenesis of lesions. We aimed to employ dynamic susceptibility contrast-enhanced perfusion MR imaging (DSC-MRI) to differentiate between infectious and neoplastic brain lesions by investigating brain microcirculation changes.

Materials and Methods

DSC-MRI perfusion studies of one hundred consecutive patients with non-cortical neoplastic (n = 54) and infectious (n = 46) lesions were retrospectively assessed. MRI examinations were performed using a 1.5-T scanner. A preload of paramagnetic contrast agent (gadolinium) was administered 30 seconds before acquisition of dynamic images, followed by a standard dose 10 seconds after starting imaging acquisitions. The relative cerebral blood volume (rCBV) values were determined by calculating the regional cerebral blood volume in the solid areas of lesions, normalized to that of the contralateral normal-appearing white matter. Discriminant analyses were performed to determine the cutoff point of rCBV values that would allow the differentiation of neoplastic from infectious lesions and to assess the corresponding diagnostic performance of rCBV when using this cutoff value.

Results

Neoplastic lesions had higher rCBV values (4.28±2.11) than infectious lesions (0.63±0.49) (p<0.001). When using an rCBV value <1.3 as the parameter to define infectious lesions, the sensitivity of the method was 97.8% and the specificity was 92.6%, with a positive predictive value of 91.8%, a negative predictive value of 98.0%, and an accuracy of 95.0%.

Conclusion

PWI is a useful complementary tool in distinguishing between infectious and neoplastic brain lesions; an elevated discriminatory value for diagnosis of infectious brain lesions was observed in this sample of patients when the rCBV cutoff value was set to 1.3.     

16层螺旋CT灌注成像对肝硬化血流状态的评估及与肝硬化程度的相关性研究

目的:探讨16层螺旋CT灌注成像对肝硬化血流状态的评估价值及其与肝硬化程度的相关性。方法:选取2014年1月至2016年1月于我院接受诊治的肝硬化患者126例作为肝硬化组,根据Child-Pugh分级分为A组(Child A级,n=35例)、B组(Child B级,n=50例)、C组(Child C级,n=41例)。另选取同期于我院接受体检的健康人员100例作为对照组。应用16层螺旋CT对受试者肝脏、脾脏、主动脉以及门静脉的层面进行CT动态增强扫描,对比CT灌注参数,采用Pearson相关性分析分析CT灌注参数与肝硬化病情严重程度的关系。结果:肝硬化组肝动脉灌注量(HAP)、肝动脉灌注指数(HPI)、肝脏血流量(TBV)以及平均通过时间(MTT)均明显高于对照组,而门静脉灌注量(PVP)、总肝灌注量(TLP)均明显低于对照组(P0.05)。A组患者HAP、HPI均明显高于C组,而PVP与TLP均明显低于C组,差异有统计学意义(P0.05);两组TBV、MTT比较无统计学差异(P0.05);而A组与B组相比以及B组与C组相比,各项CT灌注参数均无统计学差异(P0.05)。肝硬化患者病情严重程度与HAP、HPI均呈正相关关系(P0.05),而与PVP、TLP均呈负相关关系(P0.05)。结论:16层螺旋CT灌注成像对肝硬化血流状态具有一定的评估价值,且CT灌注参数的水平变化与肝硬化患者病情严重程度存在密切相关。     

In Vivo MR Imaging of Intraarterially Delivered Magnetically Labeled Mesenchymal Stem Cells in a Canine Stroke Model

Background

This study aimed to evaluate the feasibility of intraarterial (IA) delivery and in vivo MR imaging of superparamagnetic iron oxide (SPIO)-labeled mesenchymal stem cells (MSCs) in a canine stroke model.

Methodology

MSCs harvested from beagles’ bone marrow were labeled with home-synthesized SPIO. Adult beagle dogs (n = 12) were subjected to left proximal middle cerebral artery (MCA) occlusion by autologous thrombus, followed by two-hour left internal carotid artery (ICA) occlusion with 5 French vertebral catheter. One week later, dogs were classified as three groups before transplantation: group A: complete MCA recanalization, group B: incomplete MCA recanalization, group C: no MCA recanalization. 3×10⁶ labeled-MSCs were delivered through left ICA. Series in vivo MRI images were obtained before cell grafting, one and 24 hours after transplantation and weekly thereafter until four weeks. MRI findings were compared with histological studies at the time point of 24 hours and four weeks.

Principal Findings

Home-synthesized SPIO was useful to label MSCs without cell viability compromise. MSCs scattered widely in the left cerebral hemisphere in group A, while fewer grafted cells were observed in group B and no cell was detected in group C at one hour after transplantation. A larger infarction on the day of cell transplantation was associated with more grafted cells in the brain. Grafted MSCs could be tracked effectively by MRI within four weeks and were found in peri-infarction area by Prussian blue staining.

Conclusion

It is feasible of IA MSCs transplantation in a canine stroke model. Both the ipsilateral MCA condition and infarction volume before transplantation may affect the amount of grafted cells in target brain. In vivo MR imaging is useful for tracking IA delivered MSCs after SPIO labeling.     

Value of Dynamic Susceptibility Contrast Perfusion MRI in the Acute Phase of Transient Global Amnesia

Purpose

Transient global amnesia (TGA) is a transitory, short-lasting neurological disorder characterized by a sudden onset of antero- and retrograde amnesia. Perfusion abnormalities in TGA have been evaluated mainly by use of positron emission tomography (PET) or single-photon emission computed tomography (SPECT). In the present study we explore the value of dynamic susceptibility contrast perfusion-weighted MRI (PWI) in TGA in the acute phase.

Methods

From a MRI report database we identified TGA patients who underwent MRI including PWI in the acute phase and compared these to control subjects. Quantitative perfusion maps (cerebral blood flow (CBF) and volume (CBV)) were generated and analyzed by use of Signal Processing In NMR-Software (SPIN). CBF and CBV values in subcortical brain regions were assessed by use of VOI created in FIRST, a model-based segmentation tool in the Oxford Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB) Software Library (FSL).

Results

Five TGA patients were included (2 men, 3 women). On PWI, no relevant perfusion alterations were found by visual inspection in TGA patients. Group comparisons for possible differences between TGA patients and control subjects showed significant lower rCBF values bilaterally in the hippocampus, in the left thalamus and globus pallidus as well as bilaterally in the putamen and the left caudate nucleus. Correspondingly, significant lower rCBV values were observed bilaterally in the hippocampus and the putamen as well as in the left caudate nucleus. Group comparisons for possible side differences in rCBF and rCBV values in TGA patients revealed a significant lower rCBV value in the left caudate nucleus.

Conclusions

Mere visual inspection of PWI is not sufficient for the assessment of perfusion changes in TGA in the acute phase. Group comparisons with healthy control subjects might be useful to detect subtle perfusion changes on PWI in TGA patients. However, this should be confirmed in larger data sets and serial PWI examinations.     

磁共振灌注加权成像与弥散加权成像在脑胶质瘤分级诊断中的应用

目的:探讨磁共振灌注加权成像(perfusion weighted imaging,PWI)与弥散加权成像(diffusion weighted imaging,DWI)在脑胶质瘤分级诊断中的应用价值。方法:选取2012年1月-2017年6月在我院就诊并经病理证实为脑胶质瘤患者100例,其中高、低级别胶质瘤患者各44、56例。对所有患者行PWI、DWI检查,比较肿瘤不同区域表观扩散系数(apparent diffusion coefficient,ADC)、局部脑血流量(regional cerebral blood flow,rCBF),不同级别肿瘤实质区、瘤周水肿区rADC、rrCBF,根据ROC曲线分析rADC、rrCBF对不同级别胶质瘤的诊断阈值、敏感性、特异性。结果:与对侧相应正常脑实质比较,瘤周水肿区及肿瘤实质区ADC、rCBF均显著升高(P0.05);与瘤周水肿区比较,肿瘤实质区ADC、rCBF均显著升高(P0.05)。高级别肿瘤实质区rADC显著低于低级别肿瘤实质区(P0.05),rrCBF显著高于肿瘤实质区(P0.05)。高级别瘤周水肿区与低级别瘤周水肿区rADC间无显著差异(P0.05),高级别瘤周水肿区rrCBF显著高于低级别瘤周水肿区(P0.05)。在对高、低级别脑胶质瘤的分级中,rADC、rrCBF的曲线下面积(under the receiver operating characteristic curve,AUC)分别为0.957、0.978,均0.9。rADC诊断不同分级胶质瘤的敏感度是90.12%,特异度是95.26%,诊断阈值是13.12;rrCBF诊断不同分级胶质瘤的敏感度是92.31%,特异度是98.57%,诊断阈值是2.62。rADC与rrCBF诊断不同分级胶质瘤敏感度、特异度间无显著差异(P0.05)。结论:PWI、DWI能够为脑胶质瘤的分级诊断提供参考依据。     

Intravoxel Incoherent Motion Diffusion Weighted MR Imaging for Monitoring the Instantly Therapeutic Efficacy of Radiofrequency Ablation in Rabbit VX2 Tumors without Evident Links between Conventional Perfusion Weighted Images

ObjectiveTo investigate the intravoxel incoherent motion diffusion weighted imaging (IVIM-DWI) as a potential valuable marker to monitor the therapy responses of VX2 to radiofrequency ablation (RF Ablation).MethodsThe institutional animal care and use committee approved this study. In 10 VX2 tumor–bearing rabbits, IVIM-DWI examinations were performed with a 3.0T imaging unit by using 16 b values from 0 to 800 sec/mm². The true diffusion coefficient (D), pseudodiffusion coefficient (D^*) and perfusion fraction (f) of tumors were compared between before and instantly after RF Ablation treatment. The differences of D, D^* and f and conventional perfusion parameters (from perfusion CT and dynamic enhanced magnetic resonance imaging, DCE-MRI) in the coagulation necrosis area, residual unablated area, untreated area, and normal control had been calculated by compared t- test. The correlation between f or D^* with perfusion weighted CT including blood flow, BF (milliliter per 100 mL/min), blood volume, BV (milliliter per 100 mL/min), and capillary permeability–surface area, PMB (as a fraction) or from DCE-MRI: transfer constant (K_trans), extra-vascular extra-cellular volume fraction (V_e) and reflux constant (K_ep) values had been analyzed by region-of-interest (ROI) methods to calculate Pearson’s correlation coefficients.ResultsIn the ablated necrosis areas, f and D^* significantly decreased and D significantly increased, compared with residual unblazed areas or untreated control groups and normal control groups (P < 0.001). The IVIM-DWI derived f parameters showed significant increases in the residual unablated tumor area. There was no significant correlations between f or D^* and conventional perfusion parameters.ConclusionsThe IVIM-DW derived f, D and D^* parameters have the potential to indicate therapy response immediately after RF Ablation treatment, while no significant correlations with classical tumor perfusion metrics were derived from DCE-MRI and perfusion-CT measurements.     

Uninterpretable Dynamic Susceptibility Contrast-Enhanced Perfusion MR Images in Patients with Post-Treatment Glioblastomas: Cross-Validation of Alternative Imaging Options

Purpose

The purpose of this study was to evaluate the accuracy of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE) perfusion MR imaging for distinguishing tumor recurrence from post-treatment effect as alternatives to dynamic-susceptibility contrast-enhanced (DSC) perfusion MR imaging when the DSC image is uninterpretable.

Materials and Methods

This retrospective study was approved by our institutional review board. Seventy one post-treatment glioblastoma patients who showed enlarged contrast-enhancing lesions on follow-up MR images after concurrent chemoradiotherapy and uninterpretable DSC images for corresponding enhancing lesions, underwent additional DWI and DCE MR imaging. The primary outcome was the frequency of interpretable DWI and DCE MR cases in these 71 patients. The secondary outcome was the area under the receiver operating characteristic curve (AUC) of DWI and DCE imaging parameters for distinguishing tumor recurrence from post-treatment effect in selected patients with interpretable DWI and DCE images. The imaging parameters were quantified as 10% cumulative histogram cutoff of apparent diffusion coefficient (ADC10) and 90% cumulative histogram cutoff of initial area under the time signal intensity curve (IAUC90). The AUCs were cross-validated by using leave-one-out method.

Results

Of the 71 patients, the uninterpretable DSC images were associated with treatment-related hemorrhage within the corresponding enhancing lesions (n = 54, 76.1%) and a near skull base location (n = 17, 23.9%). The frequencies of interpretable DWI and DCE image were 51 (71.8%) and 59 (83.1%) of the 71 cases with uninterpretable DSC images, respectively. Of the 45 selected patients with interpretable DWI and DCE images, the combination of DWI with DCE imaging showed a superior diagnostic performance than DWI or DCE imaging alone for differentiating tumor recurrence from post-treatment effect (cross-validated AUC: 0.78 versus 0.55 and 0.73 for reader 1; cross-validated AUC: 0.78 versus 0.53 and 0.75 for reader 2, respectively). Cross-validated accuracy of the single and combined imaging parameters also showed the highest for the combination of DWI with DCE MR imaging (72.9% for reader 1; 72.5% for reader 2) and the lowest for DWI alone (54.0% for reader 1; 56.4% for reader 2). Inter-reader agreement for DCE imaging was higher than that for DWI (intraclass correlation coefficient: 0.95 versus 0.87).

Conclusion

DCE MR imaging could be a superior and more reproducible imaging biomarker than DWI for differentiating tumor recurrence from post-treatment effect in patients with post-treatment glioblastoma when DSC MR images are not interpretable.     

Impact of quantization algorithm and number of gray level intensities on variability and repeatability of low field strength magnetic resonance image-based radiomics texture features

PurposeThe purpose of this work was to investigate the impact of quantization preprocessing parameter selection on variability and repeatability of texture features derived from low field strength magnetic resonance (MR) images.MethodsTexture features were extracted from low field strength images of a daily image QA phantom with four texture inserts. Feature variability over time was quantified using all combinations of three quantization algorithms and four different numbers of gray level intensities. In addition, texture features were extracted using the same combinations from the low field strength MR images of the gross tumor volume (GTV) and left kidney of patients with repeated set up scans. The impact of region of interest (ROI) preprocessing on repeatability was investigated with a test-retest study design.ResultsThe phantom ROIs quantized to 64 Gy level intensities using the histogram equalization method resulted in the greatest number of features with the least variability. There was no clear method that resulted in the highest repeatability in the GTV or left kidney. However, eight texture features extracted from the GTV were repeatable regardless of ROI processing combination.ConclusionLow field strength MR images can provide a stable basis for texture analysis with ROIs quantized to 64 Gy levels using histogram equalization, but there is no clear optimal combination for repeatability.     

Comparison of Partial Volume Effects in Arterial and Venous Contrast Curves in CT Brain Perfusion Imaging

Purpose

In brain CT perfusion (CTP), the arterial contrast bolus is scaled to have the same area under the curve (AUC) as the venous outflow to correct for partial volume effects (PVE). This scaling is based on the assumption that large veins are unaffected by PVE. Measurement of the internal carotid artery (ICA), usually unaffected by PVE due to its large diameter, may avoid the need for partial volume correction. The aims of this work are to examine i) the assumptions behind PVE correction and ii) the potential of selecting the ICA obviating correction for PVE.

Methods

The AUC of the ICA and sagittal sinus were measured in CTP datasets from 52 patients. The AUCs were determined by i) using commercial CTP software based on a Gaussian curve-fitting to the time attenuation curve, and ii) by simple integration of the time attenuation curve over a time interval. In addition, frames acquired up to 3 minutes after first bolus passage were used to examine the ratio of arterial and venous enhancement. The impact of selecting the ICA without PVE correction was illustrated by reporting cerebral blood volume (CBV) measurements.

Results

In 49 of 52 patients, the AUC of the ICA was significantly larger than that of the sagittal sinus (p = 0.017). Measured after the first pass bolus, contrast enhancement remained 50% higher in the ICA just after the first pass bolus, and 30% higher 3 minutes later. CBV measurements were significantly lowered when the ICA was used without PVE correction.

Conclusions

Contradicting the assumptions underlying PVE correction, contrast in the ICA was significantly higher than in the sagittal sinus, even 3 minutes after the first pass of the contrast bolus. PVE correction might lead to overestimation of CBV if the CBV is calculated using the AUC of the time attenuation curves.     

Value of Perfusion-Weighted MR Imaging in the Assessment of Early Cerebral Alterations in Neurologically Asymptomatic HIV-1-Positive and HCV-Positive Patients

Background and Purpose

Asymptomatic central nervous system (CNS) involvement occurs in the early stage of the human immunodeficiency virus (HIV) infection. It has been documented that the hepatitis C virus (HCV) can replicate in the CNS. The aim of the study was to evaluate early disturbances in cerebral microcirculation using magnetic resonance (MR) perfusion-weighted imaging (PWI) in asymptomatic HIV-1-positive and HCV-positive patients, as well as to assess the correlation between PWI measurements and the clinical data.

Materials and Methods

Fifty-six patients: 17 HIV-1-positive non-treated, 18 HIV-1-positive treated with combination antiretroviral therapy (cART), 7 HIV-1/HCV-positive non-treated, 14 HCV-positive before antiviral therapy and 18 control subjects were enrolled in the study. PWI was performed with a 1.5T MR unit using dynamic susceptibility contrast (DSC) method. Cerebral blood volume (CBV) measurements relative to cerebellum (rCBV) were evaluated in the posterior cingulated region (PCG), basal ganglia (BG), temporoparietal (TPC) and frontal cortices (FC), as well as in white matter of frontoparietal areas. Correlations of rCBV values with immunologic data and liver histology activity index (HAI) were analyzed.

Results

Significantly lower rCBV values were found in the right TPC and left FC as well as in PCG in HIV-1-positive naïve (p = 0.009; p = 0.020; p = 0.012), HIV-1 cART treated (p = 0.007; p = 0.009; p = 0.033), HIV-1/HCV-positive (p = 0.007; p = 0.027; p = 0.045) and HCV-positive patients (p = 0.010; p = 0.005; p = 0.045) compared to controls. HIV-1-positive cART treated and HIV-1/HCV-positive patients demonstrated lower rCBV values in the right FC (p = 0.009; p = 0.032, respectively) and the left TPC (p = 0.036; p = 0.005, respectively), while HCV-positive subjects revealed lower rCBV values in the left TPC region (p = 0.003). We found significantly elevated rCBV values in BG in HCV-positive patients (p = 0.0002; p<0.0001) compared to controls as well as to all HIV-1-positive subjects. There were no significant correlations of rCBV values and CD4 T cell count or HAI score.

Conclusions

PWI examination enables the assessment of HIV-related as well as HCV-related early cerebral dysfunction in asymptomatic subjects. HCV-infected patients seem to reveal the most pronounced perfusion changes.     

MSCT 灌注成像在肾细胞癌临床应用价值研究*

目的:探讨肾细胞癌多层螺旋CT(MSCT)灌注成像特征,并研究其临床应用价值。方法:肾癌患者69例,采用64排多层螺旋CT对其肾脏进行平扫及灌注增强扫描,使用renal tumor perfusion软件对图像进行后处理,自动生成时间-密度曲线(TDC),各种灌注图像及感兴趣区(ROI)内的灌注参数,包括血流量(BF)、血容量(BV)、平均通过时间(MTT)及表面通透性(PS),将得到的灌注参数分别进行统计分析。结果:肾癌肿块灌注参数与已测得的正常肾皮质各灌注参数值均存在显著性差异(P值均<0.01),其中,正常肾皮质的BF值、BV值及PS值均高于肾癌组织,MTT值则相反;肾癌肿块灌注参数与已测得的正常肾髓质各灌注参数值同样存在显著性差异(p值均<0.01),正常肾髓质各灌注参数值均低于肾癌组织,而PS值二者之间差别不显著(P<0.05);肾癌患者健侧肾皮髓质灌注参数值与已测得的正常肾皮髓质各灌注参数值及肾癌患者癌旁正常肾皮髓质各灌注参数值,三者之间差异无统计学意义(P>0.05)。结论:多层螺旋CT(MSCT)灌注成像在显示肾脏形态的同时,还可定量测量皮髓质的血流灌注情况,间接反映肾脏生理特征。     

CT灌注成像在兔早期肝硬化诊断中的应用价值研究

目的:探讨CT灌注成像在兔早期肝硬化诊断中的应用价值。方法:将55只新西兰大白兔随机分为2组,其中实验组45只,对照组10只。实验组给予皮下注射葡萄籽油稀释的50%CCL4,1次/4天,前4次剂量为1.0 m L/kg,第5次剂量为1.35 m L/kg,共注射20次。对照组采用同样方法只注射相同剂量的生理盐水。每注射4次后分别对实验组兔7只和正常对照组兔2只做螺旋CT灌注扫描,分析灌注参数,同时做相应的病理学观察,将二者进行比较及统计学分析。结果:注药4次末,兔血清ALT及AST明显高于注药前,注药8次末,兔血清ALT及AST最高,之后兔血清ALT及AST轻度减低,注药前后兔血清ALT及AST的变化有统计学意义(P0.05)。而血清(ALB)水平变化不明显,仅在注药16次末后,ALB水平稍减低,但差异无统计学意义。对照组肝脏灌注参数正常,实验组从注药4次开始,HAP呈上升趋势,但注药4次末及注药8次末,实验组及对照组之间差异无统计学意义(P0.1),注药12次末后二者之间差异有统计学意义(P0.05);而HPP、HBF及HBV呈下降趋势,MTT逐渐延长,与对照组的差异均有统计学意义(P0.05)。随兔血清ALT及AST的升高,HAP逐渐升高,MTT逐渐延长,而HPP、HBF及HBV逐渐减低。实验组肝小叶正常结构破坏,肝实质被纤维组织分割成大小不一、圆形或近圆形结节(假小叶),间隔较窄,炎症轻,结节边界尚整齐;汇管区内门脉小支扩张,壁增厚。对照组肝小叶结构规整,肝板排列有序,汇管区无扩大,其内个别炎细胞浸润,肝小叶内偶见点灶状坏死。结论:全肝CT灌注功能成像可为早期肝硬化的诊断提供影像学依据,将灌注征象与病理学变化结合有利于肝硬化的早期诊断和治疗。     

Comparison of three differently shaped ROIs in free breathing breast radiotherapy setup using surface guidance with AlignRT®

BackgroundSetup accuracy within adjuvant radiotherapy of breast cancer treated in free breathing is well studied, but a comparison of the typical regions of interest (ROI) used in surface guided radiation therapy (SGRT) does not exist. The aim of this study was to estimate the setup accuracy obtained with differently shaped ROIs in SGRT.Materials and methodsA total of 573 orthogonal image pairs were analyzed from free breathing breast patients in two groups: positioning using AlignRT^® surface guidance system (Group A, n = 20), and setup using conventional laser and tattoo setup (Group L, n = 20). For SGRT, three different setup ROIs were used: a Breast-shaped, O-shaped and T-shaped (B-O and T-ROI). We evaluated the isocenter-, rotation-, pitch and arm position accuracy and residual errors for the chest wall and shoulder joint in kV orthogonal and tangential setup images with laser- or SGRT-based setup.ResultsLess isocenter variance was found in Group A than in Group L. Rotations and posture errors were larger in group L than in Group A (p ≤ 0.05). Rotation error was smaller with T-shaped ROI than with O- or B-shape (p = 0.01–0.04).ConclusionSetup with AlignRT^® improves reproducibility compared to laser setup. Between the different ROI shapes only small differences were found in the patient posture or the isocenter position in the images. The T-ROI is recommended to set up the chest wall bony structure and an additional B-ROI may be used to fine-tune the soft tissue accuracy.     

Contrast Imaging Ultrasound Detects Abnormalities in the Marmoset Ovary

The development of a functional vascular tree within the primate ovary is critical for reproductive health. To determine the efficacy of contrast agents to image the microvascular environment within the primate ovary, contrast ultrasonography was performed in six reproductive‐aged female common marmosets (Callithrix jacchus) during the late luteal phase of the cycle, following injection of Sonovue?. Regions of interest (ROIs), representing the corpus luteum (CL) and noncorpus luteum ovarian tissue (NCLOT), were selected during gray‐scale B‐mode ultrasound imaging. The magnitude of backscatter intensity of CL and NCLOT ROIs were calculated in XnView, post hoc: subsequent gamma‐variate modeling was implemented in Matlab to determine perfusion parameters. Histological analysis of these ovaries revealed a total of 11 CL, nine of which were identified during contrast ultrasonography. The median enhancement ratio was significantly increased in the CL (5.54AU; 95% CI ?2.21–68.71) compared to the NCLOT (2.82AU; 95% CI 2.73–15.06; P < 0.05). There was no difference in time parameters between the CL and NCLOT. An additional avascular ROI was identified in the ovary of Animal 5, both histologically and by ultrasonography. This cystic ROI displayed a markedly lower enhancement ratio (0.79AU) and higher time parameters than mean CL and NCLOT, including time to peak and time to wash out. These data demonstrate, for the first time, the ability of commercially available contrast agents, to differentiate structures within the nonhuman primate ovary. Contrast‐enhanced ultrasonography has a promising future in reproductive medicine. Am. J. Primatol. 74:1088‐1096, 2012. © 2012 Wiley Periodicals, Inc.