rCBV Values Research Articles

Prospective glioma grading using single-dose dynamic contrast-enhanced perfusion MRI

To evaluate the sensitivity and specificity of single-dose dynamic contrast-enhanced (DCE) perfusion magnetic resonance imaging (MRI) in prospective evaluation of glioma grading and to correlate the relative cerebral blood volume (rCBV) values with mitotic and ki-67 indexes obtained at histopathology. A total of 53 histologically proven patients with glioma were included in this study. DCE-MRI perfusion with a single dose of contrast medium was included in brain tumour protocol and prospective grading of glioma into low and high grade was done based on a previously reported rCBV cut-off value of 3. Tumours with rCBV ≥ 3 were considered to be high grade and rCBV < 3 were considered to be low grade. The sensitivity and specificity of the cut-off value were estimated. Ki-67 and mitotic indexes were also obtained on histopathological analysis along with histological grading. Based on pre-defined rCBV cut-off values, prospective grading of low- and high-grade glioma was achieved with a sensitivity and specificity of 97.22% and 100%, respectively. Significant correlation was found between the mitotic/ki-67 indexes and rCBV values when data for high- and low-grade tumours was combined. DCE-MRI performed with a single dose of contrast medium is as effective as a protocol with a double-dose of contrast medium for glioma grading using 3 T MRI and could be added to the routine evaluation protocol of brain tumours.

Differentiation of solitary brain metastasis from glioblastoma multiforme: a predictive multiparametric approach using combined MR diffusion and perfusion.

Solitary brain metastasis (MET) and glioblastoma multiforme (GBM) can appear similar on conventional MRI. The purpose of this study was to identify magnetic resonance (MR) perfusion and diffusion-weighted biomarkers that can differentiate MET from GBM. In this retrospective study, patients were included if they met the following criteria: underwent resection of a solitary enhancing brain tumor and had preoperative 3.0 T MRI encompassing diffusion tensor imaging (DTI), dynamic contrast-enhanced (DCE), and dynamic susceptibility contrast (DSC) perfusion. Using co-registered images, voxel-based fractional anisotropy (FA), mean diffusivity (MD), K(trans), and relative cerebral blood volume (rCBV) values were obtained in the enhancing tumor and non-enhancing peritumoral T2 hyperintense region (NET2). Data were analyzed by logistic regression and analysis of variance. Receiver operating characteristic (ROC) analysis was performed to determine the optimal parameter/s and threshold for predicting of GBM vs. MET. Twenty-three patients (14 M, age 32-78 years old) met our inclusion criteria. Pathology revealed 13 GBMs and 10 METs. In the enhancing tumor, rCBV, K(trans), and FA were higher in GBM, whereas MD was lower, neither without statistical significance. In the NET2, rCBV was significantly higher (p = 0.05) in GBM, but MD was significantly lower (p < 0.01) in GBM. FA and K(trans) were higher in GBM, though not reaching significance. The best discriminative power was obtained in NET2 from a combination of rCBV, FA, and MD, resulting in an area under the curve (AUC) of 0.98. The combination of MR diffusion and perfusion matrices in NET2 can help differentiate GBM over solitary MET with diagnostic accuracy of 98%.

Role of dynamic CT perfusion study in evaluating various intracranial space-occupying lesions.

Aims:Differentiating intracranial mass lesions on CT scan is challenging. The purpose of our study was to determine the perfusion parameters in various intracranial space-occupying lesions (ICSOL), differentiate benign and malignant lesions, and differentiate between grades of gliomas.Materials and Methods:We performed CT perfusion (CTP) in 64 patients, with age ranging from 17 to 68 years, having space-occupying lesions in brain and calculated relative cerebral blood flow (rCBF) and relative cerebral blood volume (rCBV).Results:We found significantly lower perfusion in low-grade gliomas as compared to high-grade tumors, lymphoma, and metastases. Similarly in infective lesions, TWT and abscesses showed significantly lower perfusion compared to TOT. In ring enhancing lesions, capsule of TWT showed significantly lower perfusion as compared to abscesses, TOT, and metastases.Conclusion:Thus, in conclusion, infective lesions can be differentiated from tumors like lymphomas, high-grade gliomas, or metastases based on perfusion parameters. The cut off value of rCBV 1.64 can be used to differentiate between low grade and high grade gliomas. However, depending only on perfusion parameters, differentiation between the tumors like lymphomas, high-grade gliomas, and metastases may not be possible.

Abstract 177: Risk of Thrombolysis-induced Hemorrhagic Transformation in Patients with Acute Ischemic Stroke: A Predictive Model Using Combined MR Perfusion Biomarkers

Purpose: Hemorrhagic transformation (HT) is a potential devastating complication of thrombolysis in patients with acute ischemic stroke (AIS). The purpose of this study was to evaluate the predictive role of MR perfusion biomarkers including increased microvascular permeability (K2) and decreased cerebral blood volume (CBV) in the infarction core to predict the risk of HT in a cohort of patients with AIS who received thrombolysis. Methods: In this retrospective study, patients were included if they: had AIS, received thrombolysis, had pre-treatment MRI (including diffusion and perfusion) and had follow-up MRI for evaluation of HT within 7 days. MR perfusion data were processed employing a Bayesian probabilistic method. Using coregistered images, voxel-based K2 and rCBV values were obtained in the region of infarction (defined by ADC &lt; 600 10 –6 mm 2 /s) and compared in patients with and without HT. Receiver operating characteristic (ROC) analysis was performed to determine the optimal parameter/s and threshold for predicting HT. Results: Forty-eight patients met study criteria: mean (SD) age was 67.5 ± 15, median baseline NIHSS was 9 (IQR: 5-24) and mean infarct volume of 34 ± 18 ml (range 11-78 ml). Thirty percent of patients (14/48) had HT. The mean K2 value was significantly ( p&lt; . 0001) higher in patients with HT (0.24 ± 0.17) versus patients without HT (0.08 ± 0.03). Mean rCBV was significantly ( p=0 .0001) lower in patients with HT (0.21 ± 0.02) compared to patients without HT (1.28 ± 0.66). ROC analysis showed a threshold and corresponding sensitivity/specificity of 0.104, 94%/84% for K2 and 0.38, 94/97% for rCBV. The combination of K2 and rCBV resulted in a higher discriminative power with an AUC of 0.97, sensitivity of 94% and specificity of 100%. In a multivariable logistic regression model that included NIHSS and infarct volume, the combined K2-rCBV classifier was an independent predictor of HT. Conclusion: Combined increased permeability and decreased CBV derived from MR perfusion have improved sensitivity and specificity, compared to either measure alone, for prediction of HT following thrombolysis. A larger clinical study is required to validate our results in an independent cohort.

Evaluation of the Posterior Cingulate Region with FDG-PET and Advanced MR Techniques in Patients with Amnestic Mild Cognitive Impairment: Comparison of the Methods

The posterior cingulate region is an area of the earliest pathological changes in amnestic mild cognitive impairment (aMCI). The utility of FDG-PET imaging in dementia is already well established. The aim of the study was to compare FDG-PET with advanced MR measurements: MR spectroscopy (MRS), perfusion weighted imaging (PWI), and diffusion tensor imaging (DTI) within the posterior cingulate region in patients with aMCI. Fifty-five patients diagnosed with aMCI (66.5 y) and 20 age-matched controls (69 y) underwent MR examination including MRS, PWI, and DTI followed by FDG-PET scanning. Values of MRS metabolite ratios (NAA/Cr, Cho/Cr, mI/Cr), PWI cerebral blood volume (rCBV), and DTI fractional anisotropy (FA) were compared to the FDG-PET rates of glucose metabolism. Compared to controls, aMCI patients showed significant (p < 0.05) glucose hypometabolism, and lower rCBV and FA values. FDG-PET results correlated significantly with rCBV values. Compared to FDG-PET, PWI showed similar and DTI greater accuracy in distinguishing aMCI from controls. According to FDG-PET findings, two groups of aMCI patients were established: those with lower (PET-positive) and normal (PET-negative) glucose uptake. PET-positive aMCI subjects showed normal MRS findings, lower rCBV and FA values, while PET-negative patients revealed normal MRS and PWI results but significantly lower FA values. Advanced MR techniques such as PWI and particularly DTI may be regarded as competitive techniques to FDG-PET. DTI was the only method to show alterations in aMCI patients with normal FDG-PET, PWI, and MRS findings. DTI seems to be a very sensitive biomarker of early degeneration in aMCI.

Imaging of gliomas at 1.5 and 3 Tesla - A comparative study

Glioma follow-up is based on MRI parameters, which are correlated with survival. Although established criteria are used to evaluate tumor response, radiological markers may be confounded by differences in instrumentation including the magnetic field strength. We assessed whether MRIs obtained at 3 Tesla (T) and 1.5T provided similar information. We retrospectively compared imaging features of 30 consecutive patients with WHO grades II and III gliomas who underwent MRI at 1.5T and 3T within a month of each other, without any clinical changes during the same period. We compared lesion volumes on fluid attenuation inversion recovery (FLAIR), ratio of cerebral blood volume (rCBV) on perfusion-weighted imaging, contrast-to-noise ratio (CNR) on FLAIR, and on post-gadolinium 3D T1-weighted sequences between 1.5T and 3T using intraclass correlation coefficient (ICC). Concordance between observers within and between modalities was evaluated using weighted-kappa coefficient (wκ). The mean ± SD delay between modalities (1.5T and 3T MRI) was 8.6 ± 5.6 days. Interobserver/intraobserver concordance for lesion volume was almost perfect for 1.5T (ICC = 0.96/0.97) and 3T (ICC = 0.99/0.98). Agreement between observers for contrast enhancement was excellent at 1.5T (wκ = 0.92) and 3T (wκ = 0.92). The tumor CNR was significantly higher for FLAIR at 1.5T (P < .001), but it was higher at 3T (P = .012) for contrast enhancement. Correlations between modalities for lesion volume (ICC = 0.97) and for rCBV values (ICC = 0.92) were almost perfect. In the follow-up of WHO grades II and III gliomas, 1.5T and 3T provide similar MRI features, suggesting that monitoring could be performed on either a 1.5 or a 3T MR magnet.

Outcome of radiosurgery for recurrent malignant gliomas: assessment of treatment response using relative cerebral blood volume.

Gamma knife radiosurgery (GKS) is efficacious for treating recurrent malignant gliomas as a salvage treatment. However, contrast enhancement alone on MR imaging remains difficult to determine the treatment response following GKS. The purpose of this study was to evaluate the radiosurgical effect for recurrent malignant gliomas and to clarify if relative cerebral blood volume (rCBV) derived from dynamic susceptibility-weighted contrast-enhanced (DSC) perfusion MR imaging could represent the treatment response. Between March 2006 and December 2008, 38 patients underwent GKS for recurrent malignant gliomas. Before and after GKS, DSC perfusion MR imaging datasets were retrospectively reprocessed and regions of interest were drawn around the contrast-enhancing region targeted with GKS. DSC-perfusion MR scans were assessed at a regular interval of two months. Following GKS for the recurrent lesions, MR images showed response (stable disease or partial response) in 26 of 38 patients (68.4 %) at post-GKS 2 months and 18 of 38 patients (47.3 %) at post-GKS 4 months. Initial mean rCBV value was 2.552 (0.586-6.178) at the pre-GKS MRI. In the response group, mean rCBV value was significantly decreased (P < 0.05) at the follow up of 2 and 4 months. However, in the treatment-failure group, mean rCBV value had no significant change. We suggest that GKS is an alternative treatment choice for the recurrent glioma. DSC-perfusion MR images are helpful to predict the treatment response after GKS.

Correlation between cerebral blood volume values and outcomes in endovascular therapy for acute ischemic stroke

BackgroundNeurointerventionalists do not agree about the optimal imaging protocol when evaluating patients with acute stroke for potential endovascular revascularization. Preintervention cerebrovascular blood volume (CBV) has been shown to predict outcomes...

Combining diffusion and perfusion differentiates tumor from bevacizumab-related imaging abnormality (bria).

A subset of patients with high-grade glioma and brain metastases who are treated with bevacizumab develop regions of marked and persistent restricted diffusion that do not reflect recurrent tumor. Here, we quantify the degree of restricted diffusion and the relative cerebral blood volume (rCBV) within these regions of bevacizumab-related imaging abnormality (BRIA) in order to facilitate differentiation of these lesions from recurrent tumor. Six patients with high-grade glioma and two patients with brain metastases who developed regions of restricted diffusion after initiation of bevacizumab were included. Six pre-treatment GBM controls were also included. Restriction spectrum imaging (RSI) was used to create diffusion maps which were co-registered with rCBV maps. Within regions of restricted diffusion, mean RSI values and mean rCBV values were calculated for patients with BRIA and for the GBM controls. These values were also calculated for normal-appearing white matter (NAWM). RSI values in regions of restricted diffusion were higher for both BRIA and tumor when compared to NAWM; furthermore RSI values in BRIA were slightly higher than in tumor. Conversely, rCBV values were very low in BRIA-lower than both tumor and NAWM. However, there was only a trend for rCBV values to be higher in tumor than in NAWM. When evaluating areas of restricted diffusion in patients with high-grade glioma or brain metastases treated with bevacizumab, RSI is better able to detect the presence of pathology whereas rCBV is better able to differentiate BRIA from tumor. Thus, combining these tools may help to differentiate necrotic tissue related to bevacizumab treatment from recurrent tumor.

Survival analysis in patients with newly diagnosed primary glioblastoma multiforme using pre- and post-treatment peritumoral perfusion imaging parameters.

The objective of this study was to evaluate if peritumoral (PT) perfusion parameters obtained from dynamic susceptibility weighted contrast enhanced perfusion MRI can predict overall survival (OS) and progression free survival (PFS) in patients with newly diagnosed glioblastoma multiforme (GBM). Twenty-eight newly diagnosed GBM patients, who were treated with resection followed by concurrent chemoradiation and adjuvant chemotherapy, were included in this study. Evaluated perfusion parameters were pre- and post-treatment PT relative cerebral blood volume (rCBV) and relative cerebral blood flow (rCBF). Proportional hazard analysis was used to assess the relationship OS, PFS and perfusion parameters. Kaplan-Meier survival estimates and log-rank test were used to characterize and compare the patient groups with high and low perfusion parameter values in terms of OS and PFS. Pretreatment PT rCBV and rCBF were not associated with OS and PFS whereas there was statistically significant association of both posttreatment PT rCBV and rCBF with OS and posttreatment rCBV with PFS (association of PFS and posttreatment rCBF was not statistically significant). Neither the Kaplan-Meier survival estimates nor the log-rank test demonstrated any differences in OS between high and low pretreatment PT rCBV values and rCBF values; however, high and low post-treatment PT rCBV and rCBF values did demonstrate statistically significant difference in OS and PFS. Our study found posttreatment, not pretreatment, PT perfusion parameters can be used to predict OS and PFS in patients with newly diagnosed GBM.

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 PurposeAsymptomatic 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 MethodsFifty-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.ResultsSignificantly 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.ConclusionsPWI 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.

The application of magnetic resonance diffusion tensor and perfusion-weighted imaging in grading of cerebral gliomas

Objective To study the application of magnetic resonance (MR),perfusion-weighted imaging (PWI) and diffusion tensor imaging (DTI) in grading gliomas.Methods 45 patients with intracranial gliomas (22 low-grade and 23 high-grade ghomas) were performed with MR examination,including conventional magnetic resonance imaging (MRI),diffusion tensor imaging (DTI) and perfusionweighted imaging (PWI).Quantitative parameters [average cerebral coefficient(ADC),fractional anisotropy(FA),reginal cerebral blood flowr(CBF),reginal cerebral blood volume (rCBV)] of solid regions of tumors,peritumoral regions and analogous locations in the contralateral WM corresponding to the tumor were measured on corresponding parameter maps generated from DTI or PWI.Then these values were compared between different groups.Receiver operating characteristic (ROC) analyses were performed to determine optimum thresholds for grading and also to calculate the sensitivity and specificity for tumor grading.Results There was a strong correlation between rCBF and rCBV of the solid regions in all 45 cases (R2 =0.9388,P ＜0.01).There was statistical significances between the ADC,FA,rCBF,rCBV values of solid regions,peritumoral region and normal white matter values (P ＜ 0.05).The difference of relative rCBV (rrCBF) and relative ADC (rADC) of solid region between high and low grade gliomas was statistical (P ＜ 0.01).So was that of the rrCBV of peritumoral regions (P ＜ 0.01).The threshold of rrCBF,rrCBV,of solid region were 2.749 and 3.058,respectively,and the diagnostic sensibility and specificity were 87％ and 100％ vs.91.3％ and 95.5％,respectively.All rrCBF,rrCBV,ADC values of solid region showed high diagnostic accuracy.Conclusion The rrCBF,rrCBV,ADC values of solid region of tumors can be used to differentiate high and low grade gliomas.The diagnostic sensitivity and specificity of rrCBF are high,and the area under the ROC curve of rrCBF is the highest,with the value of 0.974. Key words: Glioma; Magnetic resonance imaging; Diffusion tensor imaging; Perfusion-weighted imaging

Magnetic Resonance Diffusion-Weighted and Perfusion-Weighted Imaging in Differentiation of Brain Lesions

Introduction: In an educational manner are shown the diagnostic benefits of DWI and PWI in some clinically relevant cases. Aim: DWI estimates the lesion structure, water content, cellularity. PWI shows the capillary density, neovascularization. Significant differences in diffusion and perfusion were found in cases of acute ischaemia, postencephalitic lesion, metastatic lesion, lymphoma, low-and high-grade glioma. Material and Methods: DWI and PWI DSC (dynamic susceptibility contrast) Spin Echo EPI, and T1 pre, T2, T2 FLAIR, 3DT1 postcontrast images. Injector MEDRAD, Gadovist 1,0 mmol/l, dose 0,1ml/kg. Physiological serum 20 ml. Injection speed 5ml/sec. The minimum ADC (apparent diffusion coefficient) and the maximum rCBV(relative cerebral blood volume) value of each lesion was determined by placing ROI(region of interest) with area between 50-60 mm2, using the Advantage Workstation (GE Healthcare) by the radiologist. Calculation of rCBV and rADC, takes into account the maximum values in the lesion area, compared with the intact contralateral parenchymal zone. Results: Significant differences were found in these cases as follows: acute ischaemia ADC=0,0003 mm/s2, rADC=0,395, rCBV=0,113; meta ADC=0,00061 mm/s2, rADC=1,19, rCBV=0,7; lymphoma ADC=0,00071 mm/s2, rADC=1,5, rCBV=0,384; postencephalitic lesion ADC=0,00064 mm/s2, rADC=1,13, rCBV=0,44; low-grade glioma ADC=0,00184mm/s2, rADC=2,5, rCBV=0,5; high-grade glioma ADC=0,00064 mm/s2, rADC=0,816, rCBV=4. Conclusion: DWI and PWI are helpful in glioma grading, in differentiation of acute ischemia from glial tumor, in discriminating between high-grade glioma and lymphoma. This could help in finding the right and earlier treatment for the patients.

DCE and DSC MR perfusion imaging in the differentiation of recurrent tumour from treatment-related changes in patients with glioma

To retrospectively compare the utility of perfusion magnetic resonance imaging (MRI) in distinguishing treatment-related changes from recurrent disease in glioma patients. Thirty-one patients with histologically diagnosed gliomas and increased enhancement after or during concurrent (chemo-) radiation therapy were enrolled. They underwent dynamic contrast-enhanced (DCE) permeability MRI followed by dynamic susceptibility contrast (DSC) perfusion MRI. The vascular transfer constant (rK(trans)) and initial areas under the concentration curve (riAUC) were obtained from DCE MRI, and cerebral blood volume (rCBV) was obtained from DSC MRI. Patients were classified as having treatment-related changes or recurrent tumours based on clinicoradiological results or pathological results from surgery. Nineteen patients were diagnosed as having recurrences and 12 patients as having treatment-related changes. The rK(trans), riAUC, and rCBV values in the recurrent group were significantly higher than the values in the group with treatment-related changes (p < 0.05). For all 31 patients, there was no significant difference between DSC MRI and DCE MRI for the differentiating power between recurrence and treatment-related changes (p = 0.7227). However, when including only the 24 patients with concordant values of rK(trans) and riAUC, DCE MRI showed a significant AUC value of 0.786 in the receiver operating characteristic (ROC) curve analysis (p = 0.003), whereas DSC MRI did not (AUC = 0.643, p = 0.229). MRI perfusion images appear to show promise in distinguishing treatment-related changes from recurrent tumours. When both rK(trans) and riAUC show concordant values, DCE MRI seems to be more powerful than DSC MRI in the differentiation of recurrence from treatment-related changes.

Evaluation of pseudoprogression in patients with glioblastoma multiforme using dynamic magnetic resonance imaging with ferumoxytol calls RANO criteria into question

Diagnosis of pseudoprogression in patients with glioblastoma multiforme (GBM) is limited by Response Assessment in Neuro-Oncology (RANO) criteria to 3 months after chemoradiotherapy (CRT). Frequency of pseudoprogression occurring beyond this time limit was determined. Survival comparison was made between pseudoprogression and true progression patients as determined by using perfusion magnetic resonance imaging with ferumoxytol (p-MRI-Fe). Fifty-six patients with GBM who demonstrated conventional findings concerning for progression of disease post CRT were enrolled in institutional review board-approved MRI protocols. Dynamic susceptibility-weighted contrast-enhanced p-MRI-Fe was used to distinguish true progression from pseudoprogression using relative cerebral blood volume (rCBV) values. rCBV of 1.75 was assigned as the cutoff value. Participants were followed up using RANO criteria, and survival data were analyzed. Twenty-seven participants (48.2%) experienced pseudoprogression. Pseudoprogression occurred later than 3 months post CRT in 8 (29.6%) of these 27 participants (ie, 8 [14.3%] of the 56 patients meeting the inclusion criteria). Overall survival was significantly longer in participants with pseudoprogression (35.2 months) compared with those who never experienced pseudoprogression (14.3 months; P < .001). Pseudoprogression presented after 3 months post CRT in a considerable portion of patients with GBM, which raises doubts about the value of the 3-month time limit of the RANO criteria. Accurate rCBV measurement (eg, p-MRI-Fe) is suggested when there are radiographical concerns about progression of disease in GBM patients, regardless of any time limit. Pseudoprogression correlates with significantly better survival outcomes.

Facing contrast-enhancing gliomas: perfusion MRI in grade III and grade IV gliomas according to tumor area.

Tumoral neoangiogenesis characterizes high grade gliomas. Relative Cerebral Blood Volume (rCBV), calculated with Dynamic Susceptibility Contrast (DSC) Perfusion-Weighted Imaging (PWI), allows for the estimation of vascular density over the tumor bed. The aim of the study was to characterize putative tumoral neoangiogenesis via the study of maximal rCBV with a Region of Interest (ROI) approach in three tumor areas—the contrast-enhancing area, the nonenhancing tumor, and the high perfusion area on CBV map—in patients affected by contrast-enhancing glioma (grades III and IV). Twenty-one patients were included: 15 were affected by grade IV and 6 by grade III glioma. Maximal rCBV values for each patient were averaged according to glioma grade. Although rCBV from contrast-enhancement and from nonenhancing tumor areas was higher in grade IV glioma than in grade III (5.58 and 2.68; 3.01 and 2.2, resp.), the differences were not significant. Instead, rCBV recorded in the high perfusion area on CBV map, independently of tumor compartment, was significantly higher in grade IV glioma than in grade III (7.51 versus 3.78, P = 0.036). In conclusion, neoangiogenesis encompasses different tumor compartments and CBV maps appear capable of best characterizing the degree of neovascularization. Facing contrast-enhancing brain tumors, areas of high perfusion on CBV maps should be considered as the reference areas to be targeted for glioma grading.

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 PurposeDifferentiating 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 MethodsDSC-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.ResultsNeoplastic 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%.ConclusionPWI 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.

Feasibility Study of Perfusion Imaging Using Flat Detector CT with an Intra-Arterial Injection Protocol Compared to Conventional Multi-Slice Perfusion CT with an Intravenous Injection Protocol

This study investigated the feasibility of using intra-arterial injection-based cerebral blood volume (CBV) imaging with flat detector computed tomography (CT, IAFD-CBV). It is proven that this new method could provide comparable physiologic information as standard intravenous injection-based multi-slice computed tomography CBV imaging (IVCT-CBV). Twelve patients were examined using both IAFD-CBV and IVCT-CBV. An experienced neuroradiologist read both sets of generated CBV maps. If a physiologic perfusion disorder was detected in standard IVCT-CBV, the focus was to check whether IAFD-CBV indicated the same disorder or not. Otherwise, if no disorder was detected, relative CBV (rCBV) values at different basal ganglia regions were measured for both CBV maps and then compared. For three patients with lesions, IAFD-CBV and IVCT-CBV showed similar perfusion disorders in the corresponding regions. For nine patients without lesions, both CBV maps showed good symmetry of contrast agent (CA) distribution for left/right hemisphere, the total average of rCBV was found to be 0.94 -/+0.18 and 1.01 -/+0.14 (1.0 for perfect symmetry) in IAFD-CBV and IVCT-CBV, respectively. However, compared to IVCT-CBV, IAFD-CBV imaging required 70% less contrast agent (CA). In general, a good correlation between IAFD-CBV and IVCT-CBV was found for all 12 patients. Minor deviations of IAFD-CBV were only detected at regions supplied by the middle cerebral artery. IAFD-CBV imaging, which can be directly performed in a catheterization laboratory, was proven to be technically feasible for real-time CBV assessment of the whole brain with good accuracy, and minimized CA usage.

Role of CT perfusion imaging in evaluating the effects of multiple burr hole surgery on adult ischemic Moyamoya disease

IntroductionTo evaluate the effects of the multiple burr hole (MBH) revascularization on ischemic type adult Moyamoya disease (MMD) by computed tomography perfusion (CTP).MethodsEighty-six ischemic MMD patients received CTP 1 week before and 3 weeks after MBH operation. Fifty-seven patients received it again at 6 month and underwent digital subtraction angiography (DSA) and mRS follow-up. Cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), time to peak (TTP), and relative values of ischemic symptomatic hemispheres were measured. Differences in pre- and post-surgery perfusion CT values were assessed.ResultsThere were significant differences of CBF, TTP, and relative time to peak (rTTP) in ischemic hemisphere between 1 week before and 3 weeks after surgery, and no significant difference in relative cerebral blood flow (rCBF), CBV, relative cerebral blood volume (rCBV), MTT, relative mean transit time (rMTT). According to whether there was symptom improvement or not on 3 weeks after MBH, the rTTP value was not statistically significant in the patients whose symptoms were not improved at all on 3 weeks after operation. Six-month follow-up showed that CBF, rCBF, and rCBV values were significantly higher than those before operation. Postoperative MTT, TTP, rMTT, and rTTP values were significantly lower than those before operation.ConclusionCTP is a sensitive method to obtain functional imaging of cerebral microcirculation, which can be a noninvasive assessment of the abnormalities of intracranial arteries and cerebral perfusion changes in MMD before and after surgery. CBF and TTP map, especially the relative values of TTP, seems to have the capability of being quite sensitive to the presence of altered brain perfusion at early time after indirect revascularization.Electronic supplementary materialThe online version of this article (doi:10.1007/s00234-013-1291-1) contains supplementary material, which is available to authorized users.

Ferumoxytol enhanced resting state fMRI and relative cerebral blood volume mapping in normal human brain

The brain demonstrates spontaneous low-frequency (<0.1Hz) cerebral blood flow (CBF) fluctuations, measurable by resting state functional MRI (rs-fMRI). Ultra small superparamagnetic iron oxide particles have been shown to enhance task-based fMRI signals (cerebral blood volume fMRI or CBV-fMRI), compared to the BOLD effect, by a factor of ≈2.5 at 3T in primates and humans. We evaluated the use of ferumoxytol for steady state, resting state FMRI (CBV-rs-fMRI) and relative cerebral blood volume (rCBV) mapping, at 3T, in healthy volunteers. All standard resting state networks (RSNs) were identified in all subjects. On average the RSN Z statistics (MELODIC independent components) and volumes of the visual and default mode (DMN) networks were comparable. rCBV values were averaged for the visual (Vis) and DMN networks and correlated with the corresponding DMN and visual network Z statistics. There was a negative correlation between the rCBV and the Z statistics for the DMN, for both BOLD and CBV-rs-fMRI contrast (R2=0.63, 0.76). A similar correlation was not found for the visual network. Short repetition time rs-fMRI data were Fourier transformed to evaluate the effect of ferumoxytol on cardiac and respiratory fluctuations in the brain rs-BOLD, CBV signals. Cardiac and respiratory fluctuations decreased to baseline within large vessels post ferumoxytol. Robust rs-fMRI and CBV mapping is possible in normal human brain.