Analysis of metabolic indices in regions of abnormal perfusion in patients with high-grade glioma

BACKGROUND AND PURPOSE: MR spectroscopic imaging (MRSI) and dynamic susceptibility-contrast MR imaging (DSC-MR imaging) are functional in vivo techniques for assessing tumor metabolism and vasculature characteristics. Because tumor hypoxia is influenced by tortuous, degraded, swollen, and angiogenic tumor vasculature, regions of abnormal perfusion parameters should coexist with changes in lactate and creatine metabolite levels. MATERIALS AND METHODS: DSC-MR imaging and lactate-edited MRSI were performed on 38 treatment-naive patients with high-grade gliomas (17 grade III, 21 grade IV) before surgical diagnosis. Regions of abnormal perfusion were determined from peak height and percent recovery maps for each voxel within the spectroscopic imaging volume. Choline, creatine, and lactate levels within voxels experiencing only abnormal peak height (aPH), only abnormal recovery (aRec), and both abnormal peak height and recovery (aPH+aRec) were determined and compared to the surrounding T2 hyperintensity (T2h) and normal-appearing white matter. RESULTS: There were decreasing trends in volume from aPH to aRec to aPH+aRec regions for both grade III and grade IV gliomas. Grade IV gliomas exhibited significantly elevated choline in all abnormal perfusion regions, with reduced creatine and increased lactate in the aRec region relative to the surrounding T2h. Grade III gliomas showed trends toward increased creatine within the aPH region and reduced levels within the aRec region. CONCLUSION: Depressed creatine and elevated lactate levels confirmed the lack of oxygenation within regions of compromised vascular integrity. Identification of regions with leaky or dense vasculature and metabolic markers of hypoxia and cellular proliferation could be useful in determining the more aggressive part of the tumor for targeting, monitoring, and assessing effects of treatment.     

Prognostic value of preoperative dynamic contrast-enhanced MRI perfusion parameters for high-grade glioma patients

Introduction

The prognostic value of the dynamic contrast-enhanced (DCE) MRI perfusion and its histogram analysis-derived metrics is not well established for high-grade glioma (HGG) patients. The aim of this prospective study was to investigate DCE perfusion transfer coefficient (K^trans), vascular plasma volume fraction (v_p), extracellular volume fraction (v_e), reverse transfer constant (k_ep), and initial area under gadolinium concentration time curve (IAUGC) as predictors of progression-free (PFS) and overall survival (OS) in HGG patients.

Methods

Sixty-nine patients with suspected anaplastic astrocytoma or glioblastoma underwent preoperative DCE-MRI scans. DCE perfusion whole tumor region histogram parameters, clinical details, and PFS and OS data were obtained. Univariate, multivariate, and Kaplan–Meier survival analyses were conducted. Receiver operating characteristic (ROC) curve analysis was employed to identify perfusion parameters with the best differentiation performance.

Results

On univariate analysis, v_e and skewness of v_p had significant negative impacts, while k_ep had significant positive impact on OS (P < 0.05). v_e was also a negative predictor of PFS (P < 0.05). Patients with lower v_e and IAUGC had longer median PFS and OS on Kaplan–Meier analysis (P < 0.05). K^trans and v_e could also differentiate grade III from IV gliomas (area under the curve 0.819 and 0.791, respectively).

Conclusions

High v_e is a consistent predictor of worse PFS and OS in HGG glioma patients. v_p skewness and k_ep are also predictive for OS. K^trans and v_e demonstrated the best diagnostic performance for differentiating grade III from IV gliomas.

     

表观弥散系数在高级别胶质瘤与急性期脑梗死鉴别诊断中的应用

目的探讨表观弥散系数(ADC值)在高级别胶质瘤与急性期脑梗死鉴别诊断中的应用。方法回顾性分析经手术和病理证实的18例高级别胶质瘤及正规及时溶栓治疗的28例急性期脑梗死的常规磁共振表现和弥散加权成像(DWI)表现,对照分析高级别胶质瘤实性部分、急性期脑梗死灶中心部分及对侧正常脑组织ADC值。结果 18例高级别胶质瘤患者共发现20个病灶,其中11例病灶内合并有出血、坏死和囊变,肿瘤实质部分呈稍高信号,囊变坏死区呈明显低信号,肿瘤实质部分平均ADC值为(0.92±0.12)×10-3mm2/s,对侧相应正常部位平均ADC值为(0.79±0.09)×10-3mm2/s,差异有统计学意义(P<0.05),急性期脑梗死在DWI上表现为高或稍高信号,其ADC值明显低于对侧相应区域,平均ADC值为(0.69±0.10)×10-3mm2/s,高级别胶质瘤实性部分与急性期脑梗死平均ADC值差异有统计学意义(P<0.05)。结论 DWI表现及ADC值对高级别胶质瘤与急性期脑梗死磁共振鉴别诊断具有重要价值。     

Apparent diffusion coefficients in the evaluation of high-grade cerebral gliomas

BACKGROUND AND PURPOSE: Preliminary data indicate that apparent diffusion coefficient (ADC) values may be useful in identifying and grading primary cerebral tumors. We tested the hypothesis that ADC values can be used to differentiate tumor, edema, and normal brain tissue. METHODS: Fifteen patients with high-grade cerebral astrocytomas underwent conventional MR imaging, diffusion-weighted MR imaging, and proton MR spectroscopy. We defined tumor as an area containing the highest choline/creatine and choline/N-actetyl aspartate ratios, contrast enhancement, and abnormal T2 signal intensity. Edema was defined as tissue with normal proton MR spectra, no enhancement, and high T2 signal intensity. Normal brain was assumed if tissue had normal proton MR spectra, no enhancement, and normal T2 signal intensity in the hemispheres ipsilateral or contralateral to tumor. ADC maps were calculated and regions of interest were manually placed over areas of tumor, edema, and normal tissue. Comparisons were made by analysis of variance. For post hoc testing, the Tukey method was used to correct for the effect of multiple comparisons, and significance was accepted if P was less than .05. RESULTS:When ADC values were analyzed as a group, significant differences were found between tumor (131 + 45) and normal brain tissue (ipsilateral to tumor, 92 + 22; contralateral to tumor, 78 + 5) but not between tumor and adjacent edema (129 + 45). A plot of individual data points showed considerable overlapping among the three types of tissue sampled. CONCLUSION: As a group, ADC values helped to distinguish high-grade glioma from normal tissue but could not be used to separate high-grade glioma from surrounding edema. Individually, ADC values overlapped considerably and were not useful in our patients. The utility of ADC values (as obtained in this relatively small study) is questionable in patients with high-grade cerebral astrocytomas.     

Differentiation between solitary brain metastasis and high-grade glioma by diffusion tensor imaging

We tested our hypothesis that fractional anisotropy (FA) maps of diffusion tensor imaging could be used to differentiate between a solitary brain metastasis and a high-grade glioma. In seven patients with a solitary metastasis and seven patients with a high-grade glioma, FA values of enhancing and non-enhancing parts of the tumour were compared. Additionally, we visually assessed FA maps. No significant difference in the FA values of either the enhancing or non-enhancing part was found between the two groups. In the visual assessment, displacement of subcortical white-matter fibres was found in five of the seven metastasis patients, but in only one glioma patient. Additionally, discrimination between tumour and oedema was possible in three of the seven metastasis patients, but not in any glioma patient. Although FA values are not helpful in differentiating between the two groups, visual differences in FA values can allow the differentiation. Displacement of white-matter fibres is another finding suggestive of metastasis.     

Predicting cerebral ischemic infarct volume with diffusion and perfusion MR imaging

BACKGROUND AND PURPOSE: Diffusion and perfusion MR imaging have proved useful in the assessment of acute stroke. We evaluated the utility of these techniques in detecting acute ischemic infarction and in predicting final infarct size. METHODS: Diffusion and hemodynamic images were obtained in 134 patients within a mean of 12.3 hours of onset of acute ischemic stroke symptoms. We retrospectively reviewed patient radiology reports to determine the presence or absence of lesion identification on initial diffusion- (DW) and perfusion-weighted (PW) images. Radiologists were not blinded to the initial clinical assessment. For determination of sensitivity and specificity, the final discharge diagnosis was used as the criterion standard. Neurologists were not blinded to the DW or PW imaging findings. In 81 patients, acute lesions were compared with final infarct volumes. RESULTS: Sensitivities of DW imaging and cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) perfusion parameters were 94%, 74%, 84%, and 84%, respectively. Specificities of DW imaging, CBV, CBF, and MTT were 96%, 100%, 96%, and 96%, respectively. Results were similar in 93 patients imaged within 12 hours. In 81 patients with follow-up, regression analysis yielded r(2) = 0.9, slope = 1.24 for DW imaging; r(2) = 0.84, slope = 1.22 for CBV; r(2) = 0.35, slope = 0.44 for CBF; and r(2) = 0.22, slope = 0.32 for MTT, versus follow-up volume. A DW-CBV mismatch predicted additional lesion growth, whereas DW-CBF and DW-MTT mismatches did not. Results were similar in 60 patients imaged within 12 hours. CONCLUSION: Diffusion and hemodynamic images are sensitive and specific for detecting acute infarction. DW imaging and CBV best predict final infarct volume. DW-CBV mismatch predicts lesion growth into the CBV abnormality. CBF and MTT help identify additional tissue with altered perfusion but have lower correlation with final volume.     

ADC histograms predict response to anti-angiogenic therapy in patients with recurrent high-grade glioma

Introduction  

The purpose of this study is to evaluate apparent diffusion coefficient (ADC) maps to distinguish anti-vascular and anti-tumor effects in the course of anti-angiogenic treatment of recurrent high-grade gliomas (rHGG) as compared to standard magnetic resonance imaging (MRI).     

CT全脑灌注图像在脑梗死后交叉性小脑神经功能联系不能预后评估中的应用

目的 :运用CT全脑灌注图像评估脑梗死后交叉性小脑神经功联系不能(CCD)的临床预后。方法 :收集单侧幕上新发脑梗死115例,其中急性期55例,亚急性期60例,均在症状稳定期行320排CT全脑灌注扫描。随访CCD阳性患者2个月后Barthel指数。分析神经功能联系不能程度与Barthel指数的关系。结果 :急性期CCD阳性组共20例,成功随访12例,其小脑平均通过时间差值(ΔMTT)、达峰时间差值(ΔTTP)、脑血流量(CBF)减少率、脑血容量(CBV)减少率与2个月Barthel指数均无明显线性相关关系(均P0.05)。亚急性期CCD阳性组共25例,成功随访15例,其小脑ΔMTT、ΔTTP、CBF减少率与2个月Barthel指数均呈线性负相关(均P0.05),CBV减少率与Barthel指数无明显线性相关关系(P0.05)。结论:CT全脑灌注图像可帮助评估脑梗死后CCD患者预后。对于亚急性期脑梗死患者,CCD提示临床预后较差。     

Assessment of diffusion and perfusion deficits in patients with small subcortical ischemia

BACKGROUND AND PURPOSE: Using perfusion- and diffusion-weighted MR imaging in acute ischemic stroke of the middle cerebral artery (MCA), previous studies have shown a typical pathophysiologic pattern that is characterized by a perfusion deficit larger than the diffusion lesion (mismatch), with the final lesion usually comprising the initial diffusion lesion (core) plus parts of the initial mismatch area. Little is known about underlying pathophysiology in small ischemic stroke. In this study, we used perfusion- and diffusion-weighted MR imaging to investigate the underlying pathophysiology of small subcortical ischemia. METHODS: Six consecutive patients (age range, 42-76 years) with small subcortical ischemia were examined by using a 1.5-T MR system 2-5, 22-55, and 144-392 hours after the onset of symptoms. T2-weighted, diffusion-weighted imaging at b=0 s/mm2 and b=1000 s/mm2, and bolus-track perfusion-weighted imaging were performed. Lesion sizes were determined on the basis of T2-weighted findings as well as those of apparent diffusion coefficient (ADC) maps and CBF. RESULTS: In every patient, the initial CBF lesion was smaller than the initial ADC lesion. Both the CBF lesion and the ADC lesion increased in size from first to second examination. In all instances, however, the CBF lesion remained smaller than the ADC lesion. The CBF lesion observed during the acute phase and the one seen on the following days were both smaller than the final T2 lesion. CONCLUSION: Our data suggest that in contrast to previous findings in MCA ischemia in small subcortical infarcts tissue damage may spread beyond the area of the initial perfusion disturbance. In light of the small number of patients, further studies will have to address the relevance of this observation.     

Distinction between cerebral abscesses and high-grade neoplasms by dynamic susceptibility contrast perfusion MRI

OBJECTIVE: The purpose of the study was to determine whether dynamic susceptibility contrast perfusion MRI allowed distinction of cerebral abscesses from cystic high-grade brain neoplasms. CONCLUSION: In this small preliminary study, dynamic susceptibility perfusion MRI allowed distinction of cerebral abscesses from rim-enhancing high-grade gliomas. Validation of these results using a prospective large study is warranted.     

脑灌注MRI与脑血管造影在评价脑缺血病变中的价值

目的 通过对脑缺血性疾病患者的脑动脉血管造影和脑灌注ＭＲＩ对照，评价脑缺血性疾病中侧支循环建立情况，并试图鉴别脑缺血性病变的性质。     

Superselective cerebral arterial infusion of BCNU in high-grade glioma: the radiologist's point of view

Thirty-two patients suffering from high-grade glioma were candidates for superselective cerebral arterial infusion of 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU) after surgery and radiation therapy. There were 74 catheterizations using an 8-French guiding catheter through which a 2.5-French balloon catheter was placed into the main arterial trunk feeding the tumor. Eleven procedures were abandoned because of arterial spasm with a transient neurological deficit or because of prolonged catheterization time. Sixty-three infusions of BCNU were done, each lasting three hours. Eighty-one percent of patients showed stabilization or improvement on computed tomographic (CT) scans five weeks after treatment. We thus demonstrate the safety of supraophthalmic catheterization, the feasibility of prolonged catheterization, and the relative effectiveness of low doses of BCNU infused over a long period of time in the treatment of cerebral gliomas.     

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.     

99mTc-sestamibi brain SPECT after chemoradiotherapy is prognostic of survival in patients with high-grade glioma.

This prospective clinical study used (99m)Tc-sestamibi (MIBI) brain SPECT to assess residual tumor volume and determine whether it would be prognostic of survival at the end of cranial irradiation in patients with malignant glioma. METHODS: Fifty-seven patients with supratentorial malignant glioma were included in this clinical trial. Tomoscintigraphy was performed 4 h after an intravenous injection of MIBI (1,110 MBq). The images were obtained from a dual-head gamma-camera using fanbeam collimators. Transverse, coronal, and sagittal views were reconstructed. Metabolic tumor volume (MTV), using an ellipsoid model, was calculated from the 3 slices. The first posttherapeutic neuroradiologic evaluation was performed at the end of each patient's radiation therapy. RESULTS: (99m)Tc-MIBI brain SPECT performed at the end of cranial irradiation provided data that allowed the identification of residual tumor and could be used to accurately predict survival of malignant glioma patients, taking into account the established prognostic factors. Patients with an MTV < 32 cm(3) had a median survival of 358 d, as opposed to 238 d in patients with an MTV >or= 32 cm(3) (P = 0.05). Moreover, half of CT scans performed at the same time were considered to show doubtful or only suggestive findings. No diagnosis of tumor progression or inflammatory changes was possible. CONCLUSION: (99m)Tc-MIBI brain SPECT may help in establishing the prognosis of glioma patients at the end of radiation therapy. Consequently, the management of patients can be adapted. These new data should be considered in the design of future clinical studies of malignant glioma patients as a way to quickly assess the efficiency of therapies.     

MELAS综合征患者脑灌注异常的MRI特征

目的 探讨MELAS综合征患者的MR脑血流灌注异常特征.方法 对13例确诊的MELAS综合征患者和13名对照组受试者行流速敏感交替反转恢复免除独立T1测量(FAIREST)序列扫描,通过后处理生成脑血流量(CBF)图,分别测量他们的双侧基底节区、丘脑、颢叶和枕叶的相对脑血流量(rCBF)值,采用多元回归法分析对照组中测量部位和侧别对rCBF值的影响,将对照组、MELAS综合征组非病灶区和病灶区的rCBF值采用单因素方差分析进行比较.结果 对照组左侧基底节区、丘脑、颞叶和枕叶的rCBF值分别为0.83±0.23、1.17±0.30、0.93±0.28和1.11±0.25,右侧基底节区、丘脑、颞叶和枕叶的rCBF值分别为0.77±0.15、1.03±0,34、1.06±0.23和1.09±0.23,多元同归分析结果显示,对照组不同测量部位和侧别对于rCBF值的影响无统计学意义(P＞0.05).对照组感兴趣区的rCBF值为1.00±0.28,MELAS组综合征非病灶区和病灶区的rCBF值分别为1.01±0.31和1.95±0.43,MELAS综合征组病灶区的rCBF值大于非病灶区和对照组,差异有统计学意义(F=54.99,P＜0.01).结论MR灌注成像能够显示MELAS综合征患者发作期的脑血流改变,提示病灶区处于高灌注状态.