Dynamic Susceptibility Contrast Perfusion Research Articles

Clinical parameters outweigh diffusion- and perfusion-derived MRI parameters in predicting survival in newly diagnosed glioblastoma.

The purpose of this study was to determine the relevance of clinical data, apparent diffusion coefficient (ADC), and relative cerebral blood volume (rCBV) from dynamic susceptibility contrast (DSC) perfusion and the volume transfer constant (ktrans) from dynamic contrast-enhanced (DCE) perfusion for predicting overall survival (OS) and progression-free survival (PFS) in newly diagnosed treatment-naïve glioblastoma patients. Preoperative MR scans including standardized contrast-enhanced T1 (cT1), T2 - fluid-attenuated inversion recovery (FLAIR), ADC, DSC, and DCE of 125 patients with subsequent histopathologically confirmed glioblastoma were performed on a 3 Tesla MRI scanner. ADC, DSC, and DCE parameters were analyzed in semiautomatically segmented tumor volumes on contrast-enhanced (CE) cT1 and hyperintense signal changes on T2 FLAIR (ED). Univariate and multivariable Cox regression analyses including age, sex, extent of resection (EOR), and KPS were performed to assess the influence of each parameter on OS and PFS. Univariate Cox regression analysis demonstrated a significant association of age, KPS, and EOR with PFS and age, KPS, EOR, lower ADC, and higher rCBV with OS. Multivariable analysis showed independent significance of male sex, KPS, EOR, and increased rCBVCE for PFS, and age, sex, KPS, and EOR for OS. MRI parameters help to predict OS in a univariate Cox regression analysis, and increased rCBVCE is associated with shorter PFS in the multivariable model. In summary, however, our findings suggest that the relevance of MRI parameters is outperformed by clinical parameters in a multivariable analysis, which limits their prognostic value for survival prediction at the time of initial diagnosis.

Dynamic susceptibility contrast perfusion imaging in biopsy-proved adult medulloblastoma

Medulloblastoma (MB) is a high-grade rare brain tumor in adults, with heterogeneous imaging features and variable enhancing patterns. Diffusion and spectroscopy multimodal imaging have already been described in adult MB, yet perfusion has not been explored. This study aimed to evaluate vascularity in adult classic and desmoplastic MB, using perfusion-weighted dynamic susceptibility contrast (DSC) MRI and histopathology. Six histologically proved MB patients were classified as classic (n=3) and desmoplastic (n=3). DSC perfusion MRI was performed in three centers and retrospectively evaluated. Postprocessing included automatic arterial input function, motion and contrast leakage correction. Region of interest (ROI) delineation was performed on three perfusion slices to obtain a total of three cerebral blood volume ratios (rCBV) that were averaged to serve as the main rCBV. Permeability was evaluated on K2 maps. Low rCBVs were observed in all cases (mean rCBV=1.19±0.39). rCBV values were lower than 2 for classic MB and lower than 1 for desmoplastic MB. All cases showed an increase of permeability on K2 maps. Our preliminary results suggest that MB exhibits rCBV values close to 1 and increased permeability on DSC perfusion imaging, especially in desmoplastic cases, which could be explained by fibrous matrix. This type of perfusion pattern contrasts with those given by other enhancing subtentorial tumors such as metastasis, high-grade gliomas or hemangioblastomas.

A phase I study of chemo-radiotherapy with plerixafor for newly diagnosed glioblastoma (GB).

2068Background: Preclinical studies indicate that local recurrence after radiotherapy (RT) of Glioblastoma is dependent on recovery of tumor vasculature following RT via hypoxia-driven SDF-1 (CXCL12) secretion. We hypothesize that blocking the CXCL12/CXCR4 axis would improve local control. Methods: Newly diagnosed Glioblastoma patients were recruited to this Phase I study of a 4 week intravenous infusion of Plerixafor (Mozobil), a CXCR4 antagonist, with concurrent Temozolomide (TMZ) and radiation therapy. Three patients were treated with Plerixafor at 8.3 µg/kg/hr and six patients at 16.6 µg/kg/hr, while being monitored for dose limiting toxicities (DLTs) including grade ≥ 3 hematologic or non-hematologic adverse events. Patients underwent dynamic susceptibility contrast perfusion MRI (DSC-MRI) for quantification of relative cerebral blood volume (rCBV) values by region-of-interest analysis. Pharmacokinetic (PK) analysis of Plerixafor plasma levels were collected. Results: Since August 2014, 9 patients co...

Improved Leakage Correction for Single-Echo Dynamic Susceptibility Contrast Perfusion MRI Estimates of Relative Cerebral Blood Volume in High-Grade Gliomas by Accounting for Bidirectional Contrast Agent Exchange.

Contrast agent extravasation through a disrupted blood-brain barrier potentiates inaccurate DSC MR imaging estimation of relative CBV. We explored whether incorporation of an interstitial washout rate in a leakage-correction model for single-echo, gradient-echo DSC MR imaging improves relative CBV estimates in high-grade gliomas. We modified the traditional model-based postprocessing leakage-correction algorithm, assuming unidirectional contrast agent extravasation (Boxerman-Weisskoff model) to account for bidirectional contrast agent exchange between intra- and extravascular spaces (bidirectional model). For both models, we compared the goodness of fit with the parent leakage-contaminated relaxation rate curves by using the Akaike Information Criterion and the difference between modeled interstitial relaxation rate curves and dynamic contrast-enhanced MR imaging by using Euclidean distance in 21 patients with glioblastoma multiforme. The bidirectional model had improved Akaike Information Criterion versus the bidirectional model in >50% of enhancing tumor voxels in all 21 glioblastoma multiformes (77% ± 9%; P < .0001) and had reduced the Euclidean distance in >50% of enhancing tumor voxels for 17/21 glioblastoma multiformes (62% ± 17%; P = .0041). The bidirectional model and dynamic contrast-enhanced-derived kep demonstrated a strong correlation (r = 0.74 ± 0.13). On average, enhancing tumor relative CBV for the Boxerman-Weisskoff model exceeded that for the bidirectional model by 16.6% ± 14.0%. Inclusion of the bidirectional exchange in leakage-correction models for single-echo DSC MR imaging improves the model fit to leakage-contaminated DSC MR imaging data and significantly improves the estimation of relative CBV in high-grade gliomas.

Dynamic contrast-enhanced and dynamic susceptibility contrast perfusion MR imaging for glioma grading: Preliminary comparison of vessel compartment and permeability parameters using hotspot and histogram analysis

IntroductionDynamic susceptibility contrast (DSC)-MRI is a perfusion technique with high diagnostic accuracy for glioma grading, despite limitations due to inherent susceptibility effects. Dynamic contrast-enhanced (DCE)-MRI has been proposed as an alternative technique able to overcome the DSC-MRI shortcomings.This pilot study aimed at comparing the diagnostic accuracy of DSC and DCE-MRI for glioma grading by evaluating two estimates of blood volume, the DCE-derived plasma volume (Vp) and the DSC-derived relative cerebral blood volume (rCBV), and a measure of vessel permeability, the DCE-derived volume transfer constant Ktrans. MethodsTwenty-six newly diagnosed glioma patients underwent 3T-MR DCE and DSC imaging. Parametric maps of CBV, Vp and Ktrans were calculated and the region of highest value (hotspot) was measured on each map. Histograms of rCBV, Vp and Ktrans values were calculated for the tumor volume. Statistical differences according to WHO grade were assessed. The diagnostic accuracy for tumor grading of the two techniques was determined by ROC analysis. ResultsrCBV, Vp and Ktrans measures differed significantly between high and low-grade gliomas. Hotspot analysis showed the highest correlation with grading. Ktrans hotspots co-localized with Vp hotspots only in 56% of enhancing gliomas. For differentiating high from low-grade gliomas the AUC was 0.987 for rCBVmax, and 1.000 for Vpmax and Ktransmax. Combination of DCE-derived Vp and Ktrans parameters improved the diagnostic performance of the histogram method. ConclusionThis initial experience of DCE-derived Vp evaluation shows that this parameter is as accurate as the well-established DSC-derived rCBV for glioma grading. DCE-derived Ktrans is equally useful for grading, providing different informations with respect to Vp.

E.436 - Arterial spin labeling (ASL) technique could be used as standard clinical tool?

Introduction: The twomost commonmethods formeasuring perfusion using MRI are the Dynamic Susceptibility Contrast (DSC) approach, which identifies the passage of an intravascular contrast agent, and the Arterial Spin Labeling (ASL), which uses magnetically labeled arterial bloodwater as a diffusible flow tracer. DSC perfusion is still the more widely applied clinical technique but recent technical advances have improved the sensitivity of ASL perfusion. It has been argued that ASL perfusion images are not clinically reliable due to the low SNR. The objective of the current study was to evaluate the regional correlation between ASL perfusion measurement of CBF in healthy subjects and patients with brain tumors in different brain areas. Materials and Methods: 35 subjects were enrolled: 27 healthy subjects (19 m/17 f, 44.6 y) and 8 patients (4 m/3 f, 57 y) with different brain lesions. The study was performed using a 1.5 T MR scanner. Each subject received an ASL scan and all the routine clinical MRI scans; a DSC scan was also acquired only for patients. For all subjects, a series of ROIs in correspondence to the white matter (WM) and gray matter (GM) have been drawn on the ASL-CBF map; the same ROIs were also positioned on DSC-CBF map for all patients. The perfusion ASL values from different regions were analyzed using non parametric t-test. For patients, the ASL and DSC data have also been compared. Results and Conclusions: From the comparison between the ASL values it was found that the values of the CBF were statistically higher in the GM (33.5 ± 5.8 ml/100g/min) with respect to the WM (17.1 ± 5.7 mL/100g/min) as expected. Frompatient data analysis, it was evident that ASL andDSC values are in agreement with the type of lesions, WM, GM. Our study confirmed that the ASL technique represents a valid alternative to conventional DSC. In our experience the ASL was able to highlight the topographical distribution of CBF and to locate in patients ischemic and glial lesions.

Perfusion magnetic resonance imaging provides additional information as compared to anatomical imaging for decision-making in vestibular schwannoma

ObjectiveThe added value of perfusion MRI for decision-making in vestibular schwannoma (VS) patients is unknown. MRI offers two perfusion methods: the first employing contrast agent (dynamic susceptibility contrast (DSC)-MRI) that provides information on cerebral blood volume (CBV) and cerebral blood flow (CBF), the second by magnetic labeling of blood (arterial spin labeling (ASL)-MRI), providing CBF-images. The goal of the current study is to investigate whether DSC and ASL perfusion MRI provides complimentary information to current anatomical imaging in treatment selection process of VS. MethodsNine patients with growing VS with extrameatal diameter >9mm were included (>2mm/year and 20% volume expansion/year) and one patient with 23mm extrameatal VS without growth. DSC and ASL perfusion MRI were obtained on 3T MRI. Perfusion in VS was scored as hyperintense, hypointense or isointense compared to the contralateral region. ResultsSeven patients showed hyperintense signal on DSC and ASL sequences. Three patients showed iso- or hypointense signal on at least one perfusion map (1 patient hypointense on both DSC-MRI and ASL; 1 patient isointense on DSC-CBF; 1 patient isointense on ASL). All patients showed enhancement on post-contrast T1 anatomical scan. ConclusionPerfusion MR provides additional information compared to anatomical imaging for decision-making in VS.

Correlation of 3D Arterial Spin Labeling and Multi-Parametric Dynamic Susceptibility Contrast Perfusion MRI in Brain Tumors.

Arterial spin labeling (ASL) is an alternative method to Dynamic susceptibility contrast (DSC) perfusion MRI for brain tumors. However, ASL cerebral blood flow (CBF) can be easily affected by transit time. DSC MRI derived time to maximum of the residue function (Tmax) is possible to assess the transit time on ASL. Thirty patients with brain tumors were studied using ASL and DSC MRI. The relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), Tmax, and mean transit time (MTT) were obtained from DSC MRI. The ratios of the parameters were analyzed. ASL CBF ratio correlated with the DSC rCBF ratio (r=0.78, p<0.001) and rCBV ratio (r=0.74, p<0.001). There was a moderate correlation between ASL CBF ratio and Tmax ratio (r=-0.43, p<0.05) in brain tumors. ASL CBF strongly correlated with DSC rCBF and rCBV. In addition, a negative correlation was found between ASL CBF and Tmax in brain tumors, indicating that these parameters would be affected by transit time. This may explain why ASL CBF is different from DSC rCBF and rCBV. The decreased DSC Tmax value may suggest high vascularity in a tumor. J. Med. Invest. 63: 175-181, August, 2016.

Pre-Operative Perfusion Skewness and Kurtosis Are Potential Predictors of Progression-Free Survival after Partial Resection of Newly Diagnosed Glioblastoma.

ObjectiveTo determine whether pre-operative perfusion skewness and kurtosis derived from normalized cerebral blood volume (nCBV) histograms are associated with progression-free survival (PFS) of patients after partial resection of newly diagnosed glioblastoma.Materials and MethodsA total of 135 glioblastoma patients who had undergone partial resection of tumor (resection of < 50% of pre-operative tumor volume or surgical biopsy) confirmed with immediate postsurgical MRI and examined with both conventional MRI and dynamic susceptibility contrast (DSC) perfusion MRI before the surgery were retrospectively reviewed in this study. They had been followed up post-surgical chemoradiotherapy for tumor progression. Using histogram analyses of nCBV derived from pre-operative DSC perfusion MRI, patients were sub-classified into the following four groups: positive skewness and leptokurtosis (group 1); positive skewness and platykurtosis (group 2); negative skewness and leptokurtosis (group 3); negative skewness and platykurtosis (group 4). Kaplan-Meier analysis and multivariable Cox proportional hazards regression analysis were performed to determine whether clinical and imaging covariates were associated with PFS or overall survival (OS) of these patients.ResultsAccording to the Kaplan-Meier method, median PFS of group 1, 2, 3, and 4 was 62, 51, 39, and 41 weeks, respectively, with median OS of 82, 77, 77, and 72 weeks, respectively. In multivariable analyses with Cox proportional hazards regression, pre-operative skewness/kurtosis pattern (hazard ratio: 2.98 to 4.64; p < 0.001), Karnofsky performance scale score (hazard ratio: 1.04; p = 0.003), and post-operative tumor volume (hazard ratio: 1.04; p = 0.02) were independently associated with PFS but not with OS.ConclusionHigher skewness and kurtosis of nCBV histogram before surgery were associated with longer PFS in patients with newly diagnosed glioblastoma after partial tumor resection.

Fully automated stroke tissue estimation using random forest classifiers (FASTER)

Several clinical trials have recently proven the efficacy of mechanical thrombectomy for treating ischemic stroke, within a six-hour window for therapy. To move beyond treatment windows and toward personalized risk assessment, it is essential to accurately identify the extent of tissue-at-risk (“penumbra”). We introduce a fully automated method to estimate the penumbra volume using multimodal MRI (diffusion-weighted imaging, a T2w- and T1w contrast-enhanced sequence, and dynamic susceptibility contrast perfusion MRI). The method estimates tissue-at-risk by predicting tissue damage in the case of both persistent occlusion and of complete recanalization. When applied to 19 test cases with a thrombolysis in cerebral infarction grading of 1–2a, mean overestimation of final lesion volume was 30 ml, compared with 121 ml for manually corrected thresholding. Predicted tissue-at-risk volume was positively correlated with final lesion volume (p < 0.05). We conclude that prediction of tissue damage in the event of either persistent occlusion or immediate and complete recanalization, from spatial features derived from MRI, provides a substantial improvement beyond predefined thresholds. It may serve as an alternative method for identifying tissue-at-risk that may aid in treatment selection in ischemic stroke.

Contrast Leakage Patterns from Dynamic Susceptibility Contrast Perfusion MRI in the Grading of Primary Pediatric Brain Tumors.

The pattern of contrast leakage from DSC tissue signal intensity time curves have shown utility in distinguishing adult brain neoplasms, but has limited description in the literature for pediatric brain tumors. The purpose of this study is to evaluate the utility of grading pediatric brain tumors with this technique. A retrospective review of tissue signal-intensity time curves from 63 pediatric brain tumors with preoperative DSC perfusion MR imaging was performed independently by 2 neuroradiologists. Tissue signal-intensity time curves were generated from ROIs placed in the highest perceived tumor relative CBV. The postbolus portion of the curve was independently classified as returning to baseline, continuing above baseline (T1-dominant contrast leakage), or failing to return to baseline (T2*-dominant contrast leakage). Interobserver agreement of curve classification was evaluated by using the Cohen κ. A consensus classification of curve type was obtained in discrepant cases, and the consensus classification was compared with tumor histology and World Health Organization grade. Tissue signal-intensity time curve classification concordance was 0.69 (95% CI, 0.54-0.84) overall and 0.79 (95% CI, 0.59-0.91) for a T1-dominant contrast leakage pattern. Twenty-five of 25 tumors with consensus T1-dominant contrast leakage were low-grade (positive predictive value, 1.0; 95% CI, 0.83-1.00). By comparison, tumors with consensus T2*-dominant contrast leakage or return to baseline were predominantly high-grade (10/15 and 15/23, respectively) with a high negative predictive value (1.0; 95% CI, 0.83-1.0). For pilomyxoid or pilocytic astrocytomas, a T1-dominant leak demonstrated high sensitivity (0.91; 95% CI, 0.70-0.98) and specificity (0.90, 95% CI, 0.75-0.97). There was good interobserver agreement in the classification of DSC perfusion tissue signal-intensity time curves for pediatric brain tumors, particularly for T1-dominant leakage. Among patients with pediatric brain tumors, a T1-dominant leakage pattern is highly specific for a low-grade tumor and demonstrates high sensitivity and specificity for pilocytic or pilomyxoid astrocytomas.

The role of imaging in the management of adults with diffuse low grade glioma: A systematic review and evidence-based clinical practice guideline.

What is the optimal imaging technique to be used in the diagnosis of a suspected low grade glioma, specifically: which anatomic imaging sequences are critical for most accurately identifying or diagnosing a low grade glioma (LGG) and do non-anatomic imaging methods and/or sequences add to the diagnostic specificity of suspected low grade gliomas? These recommendations apply to adults with a newly diagnosed lesion with a suspected or histopathologically proven LGG. In patients with a suspected brain tumor, the minimum magnetic resonance imaging (MRI) exam should be an anatomic exam with both T2 weighted and pre- and post-gadolinium contrast enhanced T1 weighted imaging. CRITICAL IMAGING FOR THE IDENTIFICATION AND DIAGNOSIS OF LOW GRADE GLIOMA: In patients with a suspected brain tumor, anatomic imaging sequences should include T1 and T2 weighted and Fluid Attenuation Inversion Recovery (FLAIR) MR sequences and will include T1 weighted imaging after the administration of gadolinium based contrast. Computed tomography (CT) can provide additional information regarding calcification or hemorrhage, which may narrow the differential diagnosis. At a minimum, these anatomic sequences can help identify a lesion as well as its location, and potential for surgical intervention. IMPROVEMENT OF DIAGNOSTIC SPECIFICITY WITH THE ADDITION OF NON-ANATOMIC (PHYSIOLOGIC AND ADVANCED IMAGING) TO ANATOMIC IMAGING: Class II evidence from multiple studies and a significant number of Class III series support the addition of diffusion and perfusion weighted MR imaging in the assessment of suspected LGGs, for the purposes of discriminating the potential for tumor subtypes and identification of suspicion of higher grade diagnoses. Multiple series offer Class III evidence to support the potential for magnetic resonance spectroscopy (MRS) and nuclear medicine methods including positron emission tomography and single-photon emission computed tomography imaging to offer additional diagnostic specificity although these are less well defined and their roles in clinical practice are still being defined. Which imaging sequences or parameters best predict the biological behavior or prognosis for patients with LGG? These recommendations apply to adults with a newly diagnosed lesion with a suspected or histopathologically proven LGG. Anatomic and advanced imaging methods and prognostic stratification Multiple series suggest a role for anatomic and advanced sequences to suggest prognostic stratification among low grade gliomas. Perfusion weighted imaging, particularly when obtained as a part of diagnostic evaluation (as recommended above) can play a role in consideration of prognosis. Other imaging sequences remain investigational in terms of their role in consideration of tumor prognosis as there is insufficient evidence to support more formal recommendations as to their use at this time. What is the optimal imaging technique to be used in the follow-up of a suspected (or biopsy proven) LGG? This recommendation applies to adults with a newly diagnosed low grade glioma. In patients with a diagnosis of LGG, anatomic imaging sequences should include T2/FLAIR MR sequences and T1 weighted imaging before and after the administration of gadolinium based contrast. Serial imaging should be performed to identify new areas of contrast enhancement or significant change in tumor size, which may signify transformation to a higher grade. Advanced imaging utility may depend on tumor subtype. Multicenter clinical trials with larger cohorts are needed. For astrocytic tumors, baseline and longitudinal elevations in tumor perfusion as assessed by dynamic susceptibility contrast perfusion MRI are associated with shorter time to tumor progression, but can be difficult to standardize in clinical practice. For oligodendrogliomas and mixed gliomas, MRS may be helpful for identification of progression.

Distance to Thrombus in Acute Middle Cerebral Artery Occlusion Predicts Target Mismatch and Ischemic Penumbra

In patients with occlusion of the middle cerebral artery (MCA) treated by intravenous thrombolysis (IVT), the distance to thrombus (DT) has been proposed as a predictor of outcome. The purpose of the present study was to investigate how DT relates to dynamic susceptibility contrast perfusion metrics. Retrospective analysis was undertaken of patients who were diagnosed with acute MCA occlusion by magnetic resonance imaging and treated with IVT. Volumes of time-to-maximum (Tmax) perfusion deficits and diffusion-weighted imaging (DWI) lesions, diffusion-perfusion mismatch volumes, and the presence of target mismatch were determined. Correlations between the above stoke measures and DT were then calculated. Fifty-five patients were included. DT showed significant inverse correlations with Tmax greater than 4, 6, 8, and 10 seconds, respectively, and mismatch volumes. Using the DT group median (14 mm) as a separator, significant intergroup differences were observed for Tmax greater than 4, 6, and 8 seconds, respectively, and for mismatch volumes. Grouping DT into quartiles showed significant intergroup differences regarding mismatch volumes and Tmax values greater than 4 and 6 seconds. Binary logistic regression identified DT (odds ratio [OR] = .89; 95% confidence interval [CI], .81-.99) and DWI lesion volumes (OR = .92; 95% CI, .86-.97) as independent predictors of target mismatch. A low DT predicted target mismatch with an area under the curve of .69. DT correlates inversely with Tmax perfusion deficits and mismatch volumes and acts as an independent predictor of target mismatch.

NIMG-24HIGH SPATIOTEMPORAL DYNAMIC SUSCEPTIBILITY CONTRAST (DSC) PERFUSION MRI USING MULTIBAND ECHOPLANAR IMAGING (MB-EPI)

NIMG-24. HIGH SPATIOTEMPORAL DYNAMIC SUSCEPTIBILITY CONTRAST (DSC) PERFUSION MRI USING MULTIBAND ECHOPLANAR IMAGING (MB-EPI) Benjamin Ellingson, Kevin Leu, Whitney Pope, Albert Lai, Phioanh Nghiemphu, Linda Liau, and Timothy Cloughesy; University of California Los Angeles, Los Angeles, CA, USA BACKGROUND: Dynamic susceptibility contrast (DSC)-MRI is a commonlyusedperfusion imaging techniqueused toassessbrain tumorvascularity and angiogenesis by estimation of relative cerebral blood volume (rCBV). Despite widespread use, technical limitations lead to compromises in terms of resolution, slice coverage, and temporal resolution when acquiring dynamic data using the current single-shot echoplanar (EPI) imaging approach. In the current study we demonstrate the use of a new “multiband” (MB)-EPI sequence for multislice excitation, originally developed for fMRI as part of the Human Connectome Project, to obtain DSC perfusion MRI with whole brain coverage, higher spatial resolution, and twice the temporal resolution of current strategies. METHODS: DSC data collected using standard EPI were compared with DSC obtained using MB-EPI in 20 prospective GBM patients. Standard DSC-MRI were collected on conventional 1.5T or 3T MR scanners using a temporal resolution of 1250-1900ms, matrix size 1⁄4 96x96–128x128, and 5-20 slices with 5mm slice thickness. High spatiotemporalDSC-MRI datawere collectedona3TSiemensPrismawith temporal resolution of 600-750ms, matrix size 1⁄4 100x100–200x200, and 30-32 slices with 4mm slice thickness. Both DSC-MRI datasets were post-processed using standard leakage correction and deconvolution techniques to calculate rCBV and rCBF. RESULTS: Data collected using standard and MB-EPI showed similar dynamic contrast-to-noise, although MB-EPI showed more T1-weighting and leakage effects. RCBV maps obtained using both techniques provided similar information regarding the extent of hypervascularity within the tumor after leakage correction; however, rCBV maps calculated from MB-EPI data had more brain coverage and higher spatial resolution. Parametric maps of blood flow differed slightly due to higher temporal resolution MB-EPI data. CONCLUSION: High spatiotemporal DSC perfusion MRI is desirable and clinically feasible using MB-EPI. DSC using MB-EPI provides comparablequantitativedataand dataqualitywith betteraccuracyandspatial resolution. Neuro-Oncology 17:v153–v171, 2015. doi:10.1093/neuonc/nov225.24 Published by Oxford University Press on behalf of the Society for Neuro-Oncology 2015.

High-resolution blood-pool-contrast-enhanced MR angiography in glioblastoma: tumor-associated neovascularization as a biomarker for patient survival. A preliminary study.

The objective of the study was to determine whether tumor-associated neovascularization on high-resolution gadofosveset-enhanced magnetic resonance angiography (MRA) is a useful biomarker for predicting survival in patients with newly diagnosed glioblastomas. Before treatment, 35 patients (25 men; mean age, 64 ± 14 years) with glioblastoma underwent MRI including first-pass dynamic susceptibility contrast (DSC) perfusion and post-contrast T1WI sequences with gadobutrol (0.1 mmol/kg) and, 48 h later, high-resolution MRA with gadofosveset (0.03 mmol/kg). Volumes of interest for contrast-enhancing lesion (CEL), non-CEL, and contralateral normal-appearing white matter were obtained, and DSC perfusion and DWI parameters were evaluated. Prognostic factors were assessed by Kaplan-Meier survival and Cox proportional hazards model. Eighteen (51.42 %) glioblastomas were hypervascular on high-resolution MRA. Hypervascular glioblastomas were associated with higher CEL volume and lower Karnofsky score. Median survival rates for patients with hypovascular and hypervascular glioblastomas treated with surgery, radiotherapy, and chemotherapy were 15 and 9.75 months, respectively (P < 0.001). Tumor-associated neovascularization was the best predictor of survival at 5.25 months (AUC = 0.794, 81.2 % sensitivity, 77.8 % specificity, 76.5 % positive predictive value, 82.4 % negative predictive value) and yielded the highest hazard ratio (P < 0.001). Tumor-associated neovascularization detected on high-resolution blood-pool-contrast-enhanced MRA of newly diagnosed glioblastoma seems to be a useful biomarker that correlates with worse survival.

Reduced perfusion in white matter lesions in multiple sclerosis

To investigate dynamic susceptibility contrast (DSC) perfusion weighted imaging (PWI) in white matter lesions (WML) in patients with multiple sclerosis (MS), using automatically generated binary masks of brain tissue. WML in MS have in some studies demonstrated perfusion abnormalities compared to normal appearing white matter (NAWM), however perfusion changes in WML in MS have in general not been well documented. DSC PWI was performed at 1.5 Tesla in 69 newly diagnosed MS patients. Parametric perfusion maps representing cerebral blood volume (CBV), cerebral blood flow (CBF) and mean transit time (MTT) were obtained. Binary masks of WML, white matter (WM) and grey matter (GM) were automatically generated and co-registered to the perfusion maps. The WML mask was manually edited and modified to correct for errors in the automatic lesion detection. Perfusion parameters were derived both from WML and NAWM using the manually modified WML mask, and using the original non-modified WML mask (with and without GM exclusion mask). Differences in perfusion measures between WML and NAWM were analyzed. CBF was significantly lower (p<0.001) and MTT significantly higher (p<0.001) in WML compared to NAWM. CBV did not show significant difference between WML and NAWM. The non-modified WML mask gave similar results as manually modified WML mask if the GM exclusion mask was used in the analysis. DSC PWI revealed lower CBF and higher MTT, consistent with reduced perfusion, in WML compared to NAWM in patients with early MS. Automatically generated binary masks are a promising tool in perfusion analysis of WML.

Paradoxical perfusion metrics of high-grade gliomas with an oligodendroglioma component: quantitative analysis of dynamic susceptibility contrast perfusion MR imaging.

The aim of this study is to investigate perfusion characteristics of glioblastoma with an oligodendroglioma component (GBMO) compared with conventional glioblastoma (GBM) using dynamic susceptibility contrast (DSC) perfusion magnetic resonance (MR) imaging and microvessel density (MVD). The study was approved by the institutional review board. Newly diagnosed high-grade glioma patients were enrolled (n = 72; 20 GBMs, 14 GBMOs, 19 anaplastic astrocytomas (AAs), 13 anaplastic oligodendrogliomas (AOs), and six anaplastic oligoastrocytomas (AOAs)). All participants underwent preoperative MR imaging including DSC perfusion MR imaging. Normalized cerebral blood volume (nCBV) values were analyzed using a histogram approach. Histogram parameters were subsequently compared across each tumor subtype and grade. MVD was quantified by immunohistochemistry staining and correlated with perfusion parameters. Progression-free survival (PFS) was assessed according to the tumor subtype. GBMO displayed significantly reduced nCBV values compared with GBM, whereas grade III tumors with oligodendroglial components (AO and AOA) exhibited significantly increased nCBV values compared with AA (p < 0.001). MVD analyses revealed the same pattern as nCBV results. In addition, a positive correlation between MVD and nCBV values was noted (r = 0.633, p < 0.001). Patients with oligodendroglial tumors exhibited significantly increased PFS compared with patients with pure astrocytomas in each grade. In contrast to grade III tumors, the presence of oligodendroglial components in grade IV tumors resulted in paradoxically reduced perfusion metrics and MVD. In addition, patients with GBMO exhibited a better clinical outcome compared with patients with GBM.

Presurgical evaluation of mesial temporal lobe epilepsy with multiple advanced MR techniques at 3T

Accurate localization of the epileptogenic zone is essential for successful surgical treatment of mesial temporal lobe epilepsy (MTLE). The aim of this study was to analyze and compare the hippocampal volumetry (HV), MR spectroscopy (MRS), Dynamic susceptibility contrast (DSC) and pulsed arterial spin labeling (pASL) perfusion techniques in a large sample size of refractory MTLE patients. Forty-two patients with medically refractory MTLE who underwent preoperative evaluation and eleven normal controls were studied. Pathologic and control hippocampi were compared in terms of hippocampal volume, metabolite ratios and relative hippocampal perfusion values. By using cut-off points and asymmetry indexes, percentages of performance indicators for each technique were calculated in groups of MR (+), MR (-) and bilateral MTLE. For all techniques, a statistically significant difference was found between the pathologic and control hippocampus groups (P<0.001). Also, all of them except HV had diagnostic value in groups of MR (-) and bilateral MTLE. HV, MRS, DSC and pASL have achieved comparable performance and each of them provides important information about the lateralization of epileptogenic focus. Among those, pASL and MRS may easily be used as an adjunct to conventional MR.

ASFNR recommendations for clinical performance of MR dynamic susceptibility contrast perfusion imaging of the brain.

MR perfusion imaging is becoming an increasingly common means of evaluating a variety of cerebral pathologies, including tumors and ischemia. In particular, there has been great interest in the use of MR perfusion imaging for both assessing brain tumor grade and for monitoring for tumor recurrence in previously treated patients. Of the various techniques devised for evaluating cerebral perfusion imaging, the dynamic susceptibility contrast method has been employed most widely among clinical MR imaging practitioners. However, when implementing DSC MR perfusion imaging in a contemporary radiology practice, a neuroradiologist is confronted with a large number of decisions. These include choices surrounding appropriate patient selection, scan-acquisition parameters, data-postprocessing methods, image interpretation, and reporting. Throughout the imaging literature, there is conflicting advice on these issues. In an effort to provide guidance to neuroradiologists struggling to implement DSC perfusion imaging in their MR imaging practice, the Clinical Practice Committee of the American Society of Functional Neuroradiology has provided the following recommendations. This guidance is based on review of the literature coupled with the practice experience of the authors. While the ASFNR acknowledges that alternate means of carrying out DSC perfusion imaging may yield clinically acceptable results, the following recommendations should provide a framework for achieving routine success in this complicated-but-rewarding aspect of neuroradiology MR imaging practice.

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%.