Blood Volume Maps Research Articles

Mapping hepatic blood oxygenation by quantitative BOLD (qBOLD) MRI.

Abnormalities in hepatic oxygen delivery and oxygen consumption may serve as a significant indicator of hepatic cellular dysfunction and may predict treatment response. However, conventional and oxygen-enhanced hepatic BOLD MRI can only provide semiquantitative assessment of hepatic oxygenation. A hepatic quantitative BOLD (qBOLD) model was proposed for noninvasive mapping of hepatic venous blood oxygen saturation (Yv ) and deoxygenated blood volume (DBV) in human subjects. The validity and the estimation bias of the proposed model were evaluated by Monte Carlo simulations. Eight healthy subjects were scanned after written consent with institutional review board approval. Monte Carlo simulations demonstrated that the proposed single-compartment hepatic qBOLD model leads to significant deviation of the predicted T2* decay profile from the simulated signal due to high hepatic blood volume fraction. Small relative estimation bias for hepatic Yv and significant overestimation for hepatic DBV were observed, which can be corrected by applying the calibration curves established from simulations. After correction, the mean hepatic Yv in human subjects was 56.8 ± 6.8%, and the mean hepatic DBV was 0.190 ± 0.035, consistent with measurements from other invasive approaches. Except in regions with significant vascular contamination, the maps for hepatic Yv and DBV were relatively homogenous. With estimation bias correction, the hepatic qBOLD approach enables noninvasive mapping of hepatic blood volume and oxygenation in human subjects. The established protocol may be used to quantitatively assess hepatic tissue hypoxia in multiple liver diseases.

Perfusion MRI grading diffuse gliomas: Impact of permeability parameters on molecular biomarkers and survival

Background and purposeOur objectives were: (1) compare dynamic susceptibility-weighted (DSC) and dynamic contrast-enhanced (DCE) permeability parameters, (2) evaluate diagnostic accuracy of DSC and DCE discriminating high- and low-grade tumors, (3) analyze relationship of permeability parameters with overall (OS) and progression-free survival (PFS) and (4) assess differences in high-grade tumors classified according to molecular biomarkers. Materials and methods49 patients with histologically proved diffuse gliomas underwent DSC and DCE imaging. Parametric maps of cerebral blood volume (CBV), CBV-leakage corrected, volume transfer coefficient (Ktrans), fractional volume of the extravascular extracellular space (EES) (Ve), fractional blood plasma volume (Vp) and rate constant between EES and blood plasma (Kep) were calculated. High-grade gliomas were also classified according to isocitrate dehydrogenase (IDH), alpha-thalassemia/mental retardation syndrome X-linked (ATRX) and O6-methylguanine-dna-methyltransferase promoter methylation (MGMT) status. ResultsThere is correlation between parameters leakage, Ktrans and Vp. ROC curve analysis showed significance in both Ktrans and Ve for glioma grading. Threshold value of 0.075 for Ve generated the best combination of sensitivity (80%) and specificity (75%) in tumor gradation. Leakage was the only permeability parameter related to OS (P=0.006) and PFS (0.012); with prolonged survival for leakage values lower than 1.2. IDH-mutated high-grade tumors showed lower leakage and Ktrans values. High-grade tumors with loss of ATRX presented lower leakage and Vp values. ConclusionsBoth DSC and DCE permeability parameters serve as non-invasive method for glioma grading. Leakage was the unique permeability parameter related to survival and the best discriminating high-grade gliomas classified according to IDH and ATRX status.

Machine learning based on multi-parametric magnetic resonance imaging to differentiate glioblastoma multiforme from primary cerebral nervous system lymphoma

PurposeTo evaluate the performance of a machine learning method based on texture features in multi-parametric magnetic resonance imaging (MRI) to differentiate a glioblastoma multiforme (GBM) from a primary cerebral nervous system lymphoma (PCNSL). Materials and methodsWe included 70 patients who underwent contrast enhanced brain MRI at 3 T with brain tumors diagnosed as GBM (n = 45) and PCNSL (n = 25) in this retrospective study. Twelve histograms and texture parameters were assessed on T2-weighted images (T2WIs), apparent diffusion coefficient maps, relative cerebral blood volume (rCBV) map, and contrast-enhanced T1-weighted images (CE-T1WIs). A prediction model was developed using a machine learning method (univariate logistic regression and multivariate eXtreme gradient boosting-XGBoost) and the area under the receiver operating characteristic curve of this model was calculated via 10-fold cross validation. In addition, the performance of the machine learning method was compared with the judgments of two board certified radiologists. ResultsWith the univariate logistic regression model, the standard deviation of rCBV offered the highest AUC (0.86), followed by mean value of rCBV (0.83), skewness of CE-T1WI (0.78), mean value of CET1 (0.78), and max value of rCBV (0.77). The AUC of the XGBoost was significantly higher than the two radiologists (0.98 vs. 0.84; p < 0.01 and 0.98 vs. 0.79; p < 0.01, respectively). ConclusionThe performance of machine learning based on histogram and texture features in multi-parametric MRI was superior to that of conventional cut-off method and the board certified radiologists to differentiate a GBM from a PCNSL.

Incorporating diffusion- and perfusion-weighted MRI into a radiomics model improves diagnostic performance for pseudoprogression in glioblastoma patients.

Pseudoprogression is a diagnostic challenge in early posttreatment glioblastoma. We therefore developed and validated a radiomics model using multiparametric MRI to differentiate pseudoprogression from early tumor progression in patients with glioblastoma. The model was developed from the enlarging contrast-enhancing portions of 61 glioblastomas within 3 months after standard treatment with 6472 radiomic features being obtained from contrast-enhanced T1-weighted imaging, fluid-attenuated inversion recovery imaging, and apparent diffusion coefficient (ADC) and cerebral blood volume (CBV) maps. Imaging features were selected using a LASSO (least absolute shrinkage and selection operator) logistic regression model with 10-fold cross-validation. Diagnostic performance for pseudoprogression was compared with that for single parameters (mean and minimum ADC and mean and maximum CBV) and single imaging radiomics models using the area under the receiver operating characteristics curve (AUC). The model was validated with an external cohort (n = 34) imaged on a different scanner and internal prospective registry data (n = 23). Twelve significant radiomic features (3 from conventional, 2 from diffusion, and 7 from perfusion MRI) were selected for model construction. The multiparametric radiomics model (AUC, 0.90) showed significantly better performance than any single ADC or CBV parameter (AUC, 0.57-0.79, P < 0.05), and better than a single radiomics model using conventional MRI (AUC, 0.76, P = 0.012), ADC (AUC, 0.78, P = 0.014), or CBV (AUC, 0.80, P = 0.43). The multiparametric radiomics showed higher performance in the external validation (AUC, 0.85) and internal validation (AUC, 0.96) than any single approach, thus demonstrating robustness. Incorporating diffusion- and perfusion-weighted MRI into a radiomics model improved diagnostic performance for identifying pseudoprogression and showed robustness in a multicenter setting.

Ultra-high resolution blood volume fMRI and BOLD fMRI in humans at 9.4 T: Capabilities and challenges

Functional mapping of cerebral blood volume (CBV) changes has the potential to reveal brain activity with high localization specificity at the level of cortical layers and columns. Non-invasive CBV imaging using Vascular Space Occupancy (VASO) at ultra-high magnetic field strengths promises high spatial specificity but poses unique challenges in human applications. As such, 9.4 T B1+ and B0 inhomogeneities limit efficient blood tagging, while the specific absorption rate (SAR) constraints limit the application of VASO-specific RF pulses. Moreover, short T2* values at 9.4 T require short readout duration, and long T1 values at 9.4 T can cause blood-inflow contaminations.In this study, we investigated the applicability of layer-dependent CBV-fMRI at 9.4 T in humans. We addressed the aforementioned challenges by combining multiple technical advancements: temporally alternating pTx B1+ shimming parameters, advanced adiabatic RF-pulses, 3D-EPI signal readout, optimized GRAPPA acquisition and reconstruction, and stability-optimized RF channel combination. We found that a combination of suitable advanced methodology alleviates the challenges and potential artifacts, and that VASO fMRI provides reliable measures of CBV change across cortical layers in humans at 9.4 T. The localization specificity of CBV-fMRI, combined with the high sensitivity of 9.4 T, makes this method an important tool for future studies investigating cortical micro-circuitry in humans.

Perfusion magnetic resonance imaging changes in normal appearing brain tissue after radiotherapy in glioblastoma patients may confound longitudinal evaluation of treatment response

BackgroundThe aim of this study was assess acute and early delayed radiation-induced changes in normal-appearing brain tissue perfusion as measured with perfusion magnetic resonance imaging (MRI) and the dependence of these changes on the fractionated radiotherapy (FRT) dose level.Patients and methodsSeventeen patients with glioma WHO grade III-IV treated with FRT were included in this prospective study, seven were excluded because of inconsistent FRT protocol or missing examinations. Dynamic susceptibility contrast MRI and contrast-enhanced 3D-T1-weighted (3D-T1w) images were acquired prior to and in average (standard deviation): 3.1 (3.3), 34.4 (9.5) and 103.3 (12.9) days after FRT. Pre-FRT 3D-T1w images were segmented into white- and grey matter. Cerebral blood volume (CBV) and cerebral blood flow (CBF) maps were calculated and co-registered patient-wise to pre-FRT 3D-T1w images. Seven radiation dose regions were created for each tissue type: 0–5 Gy, 5–10 Gy, 10–20 Gy, 20–30 Gy, 30–40 Gy, 40–50 Gy and 50–60 Gy. Mean CBV and CBF were calculated in each dose region and normalised (nCBV and nCBF) to the mean CBV and CBF in 0-5 Gy white- and grey matter reference regions, respectively.ResultsRegional and global nCBV and nCBF in white- and grey matter decreased after FRT, followed by a tendency to recover. The response of nCBV and nCBF was dose-dependent in white matter but not in grey matter.ConclusionsOur data suggest that radiation-induced perfusion changes occur in normal-appearing brain tissue after FRT. This can cause an overestimation of relative tumour perfusion using dynamic susceptibility contrast MRI, and can thus confound tumour treatment evaluation.

Combined application of multi-parameter semiquantitative Alberta stroke program early CT score to assess infarction severity in acute ischemic stroke

Objective: To explore the significance of multi-parameter semiquantitative Alberta Stroke Program Early CT Score (ASPECTS) in detecting core infarction in acute ischemic stroke (AIS) patients. Methods: Twenty-one consecutive AIS patients from Beijing Hospital were retrospectively reviewed in this study from August 2016 to August 2017. All the patients presented within 6 hours since symptom onset.All the patients underwent one-stop dynamic whole brain 4D CTA-CTP scan before treatments (intravenous thrombolysis, mechanical thrombectomy, or other endovascular recanalization). MRI scan was performed in all patients 3 to 7 days after initial administration. Multi-parameter ASPECTS was calculated on the affected hemisphere regarding noncontrast CT (NCCT) map, cerebral blood flow (CBF) map, cerebral blood volume (CBV) map, mean transit time (MTT) map and MRI-DWI map by subtracting 1 point from 10 for any abnormalities visually detected. The evaluative consistency and diagnostic efficiency were analyzed by Pearson's χ(2) test, kappa identity test, and Kendall's coefficient of concordance using IBM SPSS statistics 22.0 software. Results: Compared with DWI-ASPECTS or follow-up NCCT-ASPECTS, CBV-ASPECTS had the best performance on both the kappa identity test (kappa coefficient κ=0.74)and Kendall's coefficient of concordance (τ=0.70). All the values of sensitivity (77.8%), specificity (95.5%), positive likelihood ratio (17.27) and AUC(0.87)were the highest in CBV-ASPECTS, followed by dMTT-ASPECTS. Meanwhile, the misdiagnosis rate (4.5%), missed diagnosis rate (22.2%) and negative likelihood ratio were the lowest in CBV-ASPECTS, followed by dMTT-ASPECTS. dMTT-ASPECTS had the same specificity(95.5%) as CBV-ASPECTS did and it could reveal the infarction in the areas where CBV map showed normal. NCCT-ASPECTS had the lowest sensitivity (64.7%) and highest missed diagnosis rate (35.3%). The misdiagnosis rate of CBF-ASPECTS was the highest (25.2%) and AUC was the lowest (0.76). Conclusions: Multi-parameter semiquantitative ASPECTS may predict the infarction accurately in AIS patients. Compared with the single parameter of NCCT-ASPECTS, this new method may have better detectability and diagnostic performance.

Quantitative assessment of local perfusion change in acute intracerebral hemorrhage areas with and without "dynamic spot sign" using CT perfusion imaging.

Positive "dynamic spot sign" has been proven to be a potential risk factor for acute intracerebral hemorrhage (ICH) expansion, but local perfusion change has not been quantitatively investigated. To quantitatively evaluate perfusion changes at the ICH area using computed tomography perfusion (CTP) imaging. Fifty-three patients with spontaneous ICH were recruited. Unenhanced computed tomography (NCCT), CTP within 6 h, and follow-up NCCT were performed for 21 patients in the "spot sign"-positive group and 32 patients in the control group. Cerebral perfusion change was quantitatively measured on regional cerebral blood flow/regional cerebral blood volume (rCBF/rCBV) maps. Regions of interest (ROIs) were set at the "spot-sign" region and the whole hematoma area for "spot-sign"-positive cases, and at one of the highest values of three interested areas and the whole hematoma area for the control group. Hematoma expansion was determined by follow-up NCCT. For the "spot-sign"-positive group, the average rCBF (rCBV) values at the "spot-sign" region and the whole hematoma area were 21.34 ± 15.24 mL/min/100 g (21.64 ± 21.48 mL/100g) and 5.78 ± 6.32 mL/min/100 g (6.07 ± 5.45 mL/100g); for the control group, the average rCBF (rCBV) values at the interested area and whole hematoma area were 2.50 ± 1.83 mL/min/100 g (3.13 ± 1.96 mL/100g) and 3.02 ± 1.80 mL/min/100 g (3.40 ± 1.44 mL/100g), respectively. Average rCBF and rCBV values of the "spot-sign" region were significantly different from other regions ( P < 0.001; P = 0.004). The average volumes of hematoma expansion in the "spot-sign"-positive and control groups were 25.24 ± 19.38 mL and -0.41 ± 1.34 mL, respectively. The higher perfusion change at ICH on CTP images may reflect the contrast extravasation and be associated with the hematoma expansion.

Quantitative dynamic susceptibility contrast perfusion-weighted imaging-guided customized gamma knife re-irradiation of recurrent high-grade gliomas

Treatment of recurrent high-grade gliomas (rHGG) has always been challenging. This study aimed to explore the treatment effect of quantitative dynamic susceptibility contrast perfusion-weighted imaging (DSC-PWI)-guided gamma knife radiosurgery (GKRS) on rHGG. Between April 2014 and July 2016, 26 consecutive patients were treated by quantitative DSC-PWI-guided GKRS as salvage treatment for rHGG. The gross tumor volume (GTV) was defined as the high perfusion area on absolute cerebral blood volume maps, with a cutoff value of 22ml/100g. The clinical target volume (CTV) encompassed the GTV by 3mm. Overall survival (OS) and progression-free survival (PFS) were calculated by the Kaplan-Meier method. Prognostic factors were tested by the log-rank (Mantel-Cox) test. With a median follow-up of 32 months, the median PFS after GKRS was 8months (95% CI [6, 12]); the 1- and 2-year survival rates were 30.8 and 11.5%, respectively. The median OS was 25.5months (95% CI [18, 40]); the 1- and 2-year survival rates were 96.2 and 57.7%, respectively. Pathology grade and CTV were identified as prognostic factors for PFS. However, none of the parameters tested were independent prognostic factors for OS among these selected patients. No severe radiotoxicity was observed among all patients. Quantitative DSC-PWI-guided GKRS is feasible for the treatment of rHGG and that these outcomes remain to be validated. Despite this, we think that carefully selected patients can benefit from this treatment method.

Exploratory Radiomics in Computed Tomography Perfusion of Prostate Cancer.

An evaluation if radiomic features of CT perfusion (CTP) can predict tumor grade and aggressiveness in prostate cancer was performed. Forty-seven patients had biopsy-confirmed prostate cancer, and received a CTP. Blood volume (BV), blood flow (BF) and mean transit time (MTT) maps were derived and 1,701 radiomic features were determined per patient. Regression models were built to estimate post-surgical Gleason score (GS), microvessel density (MVD) and distinguish between the different risk groups. Six out of the 47 patients had to be excluded from further analysis. A weak relationship between postsurgical GS and one radiomic parameter was found (R2=0.21, p=0.01). The same parameter combined with MTT inter-quartile range was prognostic for the risk group categorisation (AUC=0.81). Two different radiomic parameters were able to distinguish between low-intermediate risk and high-intermediate risk (AUC=0.77). Four parameters correlated with MVD (R2=0.53, p<0.02). This exploratory study shows the potential of radiomics to classify prostate cancer.

Detection of Recurrent/Residual Hepatocellular Carcinoma: Single-Center Retrospective Comparative Study Between Parenchymal Blood Volume Mapping Using Cone Beam CT and Multiphase Dynamic CT

Detection of Recurrent/Residual Hepatocellular Carcinoma: Single-Center Retrospective Comparative Study Between Parenchymal Blood Volume Mapping Using Cone Beam CT and Multiphase Dynamic CT

Computed Tomography Perfusion Alberta Stroke Program Early Computed Tomography Score Is Associated with Hemorrhagic Transformation after Acute Cardioembolic Stroke.

Alberta Stroke Program Early Computed Tomography (CT) score (ASPECTS) has been applied to CT perfusion (CTP) with good interrater agreement to predict early ischemic stroke, and it can be useful in decision making in acute ischemic stroke. The aim of the present study was to assess the predictive value of CTP ASPECTS of hemorrhagic transformation (HT) in acute cardioembolic stroke. This is a single-enter, retrospective study. All patients hospitalized with acute cardioembolic stroke from January 2008 to September 2013 were included. ASPECTS of baseline non-contrast CT, CTP maps of cerebral blood volume (CBV), cerebral blood flow, and mean transit time were collected from 52 consecutive patients with less than 12-h anterior circulation ischemic stroke. MRI scan was performed within 72 h of symptom onset after index stroke including T2*-weighted gradient echo to identify HT. For bleeding risk assessment, CTP and diffusion-weighted imaging ASPECTS were categorized into 0–7 or 8–10. Baseline characteristics, ASPCETS scores and HT were compared. Eighteen (34.6%) patients had HT and four (7.7%) developed symptomatic HT. On univariate analysis, the proportion of patients with CBV-ASPECTS 0–7 was significantly higher in HT patients as compared to patients without HT (44 versus 9%, P = 0.005). CBV ASPECTS 0–7 remained independent prognostic factors for HT after adjustment for clinical baseline variables. CBV ASPECTS could be of value to predict HT risk after acute cardioembolic stroke and may be a quick risk assessment approach before reperfusion therapy.

Clustering of multi-parametric functional imaging to identify high-risk subvolumes in non-small cell lung cancer

Background and purposeWe aimed to identify tumour subregions with characteristic phenotypes based on pre-treatment multi-parametric functional imaging and correlate these subregions to treatment outcome. The subregions were created using imaging of metabolic activity (FDG-PET/CT), hypoxia (HX4-PET/CT) and tumour vasculature (DCE-CT). Materials and methods36 non-small cell lung cancer (NSCLC) patients underwent functional imaging prior to radical radiotherapy. Kinetic analysis was performed on DCE-CT scans to acquire blood flow (BF) and volume (BV) maps. HX4-PET/CT and DCE-CT scans were non-rigidly co-registered to the planning FDG-PET/CT. Two clustering steps were performed on multi-parametric images: first to segment each tumour into homogeneous subregions (i.e. supervoxels) and second to group the supervoxels of all tumours into phenotypic clusters. Patients were split based on the absolute or relative volume of supervoxels in each cluster; overall survival was compared using a log-rank test. ResultsUnsupervised clustering of supervoxels yielded four independent clusters. One cluster (high hypoxia, high FDG, intermediate BF/BV) related to a high-risk tumour type: patients assigned to this cluster had significantly worse survival compared to patients not in this cluster (p = 0.035). ConclusionsWe designed a subregional analysis for multi-parametric imaging in NSCLC, and showed the potential of subregion classification as a biomarker for prognosis. This methodology allows for a comprehensive data-driven analysis of multi-parametric functional images.

Detection of cartilage invasion in laryngeal carcinoma with dynamic contrast-enhanced CT.

ObjectiveStaging of laryngeal cancer largely depends on cartilage invasion. Presence of cartilage invasion affects treatment choice and prognosis. On MRI and contrast‐enhanced CT (CECT) it may be challenging to differentiate cartilage invasion from inflammation. The purpose of this study is to compare the diagnostic properties of dynamic contrast‐enhanced CT (DCECT) and CECT for visual detection of cartilage invasion in laryngeal cancer.Study DesignProspective cohort study.MethodsPatients with T3 or T4 laryngeal squamous cell carcinoma treated with total laryngectomy were evaluated using 0.625 mm slice CT. DCECT derived permeability and blood volume maps and CECT images were visually evaluated for the presence of invasion of the cartilaginous T‐stage subsites of laryngeal cancer, by detecting continuity with the tumor‐bulk of increased permeability, increased blood volume, and enhancement. Histological evaluation of the surgical total laryngectomy specimen served as the gold standard. Sensitivity, specificity, negative predictive value, and positive predictive value were calculated and compared using the McNemar and Chi‐squared test.ResultsFrom 14 included patients, a total of 462 subsites were available for T‐stage analysis, of which 84 were cartilage. The median time between CT imaging and total laryngectomy was 1 day (range 1–34 days). There was no significant difference in the detection of cartilage invasion between DCECT and CECT. The sensitivity of CECT was better for all subsites combined (0.85 vs. 0.75; p < 0.01).ConclusionDCECT does not improve visual detection of cartilage invasion in T3 and T4 laryngeal cancer compared to CECT.Level of Evidence2b, individual cohort study.

Bimodality Imaging of Primary Cervical Tumors Before and During Concurrent Chemoradiation Therapy Suggests Association Between Changes in Tumor Blood Volume and Treatment Response

To investigate changes of FDG-PET and perfusion CT parameters in cervical cancer patients before and during CCRT and to correlate these parameters and their changes with metabolic response evaluated post CCRT. Pretreatment perfusion CT and PET/CT were performed on 20 patients, of whom 19 also underwent during treatment imaging after 4 weeks of CCRT. Stage distribution was as follows: 1 IIA1, 2 IIA2, 11 IIB, 1 IIIA, 5 IIIB. Three-dimensional co-registered parametric maps of SUV, Blood Flow (BF), Blood Volume (BV), and Permeability (PMB) were generated. Summary statistics for these and other parameters were calculated within 3 regions: primary tumor, healthy muscle receiving prescription dose, and muscle in a peripheral low dose region. Baseline values and their changes were examined for association with therapy outcome as evaluated by FDG-PET/CT 3 months post-CCRT in 17 patients (14 with complete metabolic response (CMR) and 3 with new distant disease). In tumors, during- versus pre- treatment values decreased significantly for the following parameters: volume (66.2 +/- 65.1 vs. 17.4+/-15.0 ml, P = 0.0015), SUVmax (11.0 +/- 3.9 vs. 6.7 +/- 3.7, P = 0.0002), and SUVmean (5.1 +/- 1.7 vs. 3.5 +/-1.6, P = 0.0010). BVmean (10.9 +/- 2.6 vs. 12.1 +/- 3.4 ml/100ml, P = 0.0013) and PMBmean (18.8 +/- 5.3 vs. 25.4 +/- 7.2 ml/100 ml/min, P < 0.0001) increased significantly. Coefficients of variation for BF, BV, PMB, and SUV decreased significantly (P < 0.003) indicating therapy-induced improvement in the homogeneity of perfusion and FDG uptake. In muscle pre-treatment perfusion values were significantly lower (P < 0.0001) than the corresponding values in tumors: BFmean (22.3 +/- 13.6 ml/100 ml/min), BVmean (2.9 +/- 1.8 ml/100 ml), and PMBmean (2.9 +/- 2.4 vs. ml/100 ml/min). For both muscle locations pre- and during treatment BFmean and BVmean were not significantly different indicating that BVmean changes in tumors reflected tumor- specific vasculature response to radiation. On univariate analysis FDG-PET and CT perfusion baseline values were not associated with treatment outcome. Among the examined parameters both absolute and relative differences in BVmean were significantly associated with treatment outcome. In patients with CMR BVmean increased by 32.4% +/- 25.8%, whereas in patients with new disease BVmean decreased by 20.8% +/- 10.9% (P < 0.01). CCRT significantly changes both PET and perfusion values in cervical tumors but not in healthy muscle. In our patient cohort blood volume increase during treatment was associated with complete metabolic response to therapy, a finding in line with observations from serial dynamic MRI studies. This suggests a potential role for perfusion CT in early evaluation of treatment response to chemoradiotherapy for cervical patients.

Whole-tumor histogram analysis of the cerebral blood volume map: tumor volume defined by 11C-methionine positron emission tomography image improves the diagnostic accuracy of cerebral glioma grading.

This study aimed to compare the tumor volume definition using conventional magnetic resonance (MR) and 11C-methionine positron emission tomography (MET/PET) images in the differentiation of the pre-operative glioma grade by using whole-tumor histogram analysis of normalized cerebral blood volume (nCBV) maps. Thirty-four patients with histopathologically proven primary brain low-grade gliomas (n=15) and high-grade gliomas (n=19) underwent pre-operative or pre-biopsy MET/PET, fluid-attenuated inversion recovery, dynamic susceptibility contrast perfusion-weighted magnetic resonance imaging, and contrast-enhanced T1-weighted at 3.0T. The histogram distribution derived from the nCBV maps was obtained by co-registering the whole tumor volume delineated on conventional MR or MET/PET images, and eight histogram parameters were assessed. The mean nCBV value had the highest AUC value (0.906) based on MET/PET images. Diagnostic accuracy significantly improved when the tumor volume was measured from MET/PET images compared with conventional MR images for the parameters of mean, 50th, and 75th percentile nCBV value (p=0.0246, 0.0223, and 0.0150, respectively). Whole-tumor histogram analysis of CBV map provides more valuable histogram parameters and increases diagnostic accuracy in the differentiation of pre-operative cerebral gliomas when the tumor volume is derived from MET/PET images.

Mechanical Thrombectomy for Acute Basilar Artery Occlusion in Early Therapeutic Time Window

Background: The natural history of basilar artery occlusion (BAO) is devastating, with morbidity rates increasing up to 80%. However, the efficacy of recanalization therapy for BAO has not been established as yet. Objective: We analyzed consecutive cases of BAO treated with mechanical thrombectomy (MT) to evaluate its safety and efficacy and to determine factors associated with the prognosis. Methods: Between October 2011 and September 2016, MT was performed in 34 patients with BAO. MT was performed using the Penumbra system and stent retriever. CT perfusion was used for evaluating patients. Cerebral blood flow (CBF) maps and cerebral blood volume (CBV) maps were evaluated. CBF/CBV mismatch was defined as ≥50% penumbra. Clinical outcomes were correlated with demographic, clinical, and radiographic findings. Results: The median baseline National Institutes of Health Stroke Scale score was 29 (14-33). The recanalization rate (≥thrombolysis in cerebral infarction grades 2b) was 100%. The median onset to recanalization time (OTR) was 197 (160-256) min. Favorable outcomes (modified Rankin Scale ≤2) at 90 days occurred in 56% (n = 19 of 34). The mortality rate at 90 days was 12% (n = 4 of 34). In univariate analysis, intravenous (IV) recombinant tissue-type plasminogen activator (rt-PA) use, and OTR were significantly associated with favorable outcomes. In a multivariate logistic regression model, IV rt-PA use and lower National Institute of Health Stroke Scale score were significantly related to favorable outcomes. Conclusion and Relevance: Multimodal endovascular therapy using the Penumbra system and stent retriever demonstrated a high recanalization rate and favorable outcomes for BAO. Both devices were feasible and effective in the treatment of BAO. An approach combining MT with IV thrombolysis provided a better recanalization rate and more favorable clinical outcomes.

The diagnostic value of susceptibility-weighted imaging for ischemic penumbra in patients with acute ischemic stroke.

The ischemia penumbra area is not easy to be detected accurately using noninvasive imaging methods. We aim to assess the diagnostic value of susceptibility-weighted imaging (SWI) for ischemic penumbra in patients with acute ischemic stroke. A retrospective analysis was carried out in 47 patients with ischemic stroke involving the middle cerebral artery. Mean transit time (MTT), time to peak, relative cerebral blood flow, and relative cerebral blood volume maps were created after image processing. No significant difference was found in the mismatch between the SWI and diffusion-weighted imaging (SWI-DWI) or in the MTT-DWI mismatch scores (P= 0.056, Kappa = 0.864). SWI provides information comparable to PWI and, thus, could serve as a reliable magnetic resonance technique for assessing ischemic penumbrae.

Abstract CT068: Tumor treating fields in patients with glioblastomas: Evaluation of treatment response using advanced mr imaging techniques

Abstract Introduction: Tumor treating fields (TTFields) is a new modality for the treatment of patients with newly diagnosed and recurrent glioblastomas (GBMs). TTFields system delivers low intensity, intermediate frequency alternating electric field directly to brain causing neoplastic cell death with minimal effect on the normal dividing cells. The purpose of present investigator sponsored trial was to evaluate the effects of TTFields in GBM patients using diffusion tensor imaging (DTI), perfusion weighted imaging (PWI) and 3D-echoplanar spectroscopic imaging (EPSI). Methods: Two patients with newly diagnosed GBM and six patients with recurrent GBMs previously treated with standard of care maximal safe resection and chemo-radiation therapy received TTFields. Patients underwent baseline (prior to TTFields) and two follow-up (one and two months post initiation of TTFields) MR imaging on a 3T MR system. DTI data were acquired using 30 directions with a single-shot spin-echo EPI sequence. After motion and eddy current correction of raw DTI data, parametric maps [mean diffusivity (MD), fractional anisotropy (FA)] were generated using in-house developed algorithm. For PWI, T2* weighted gradient-echo EPI sequence was acquired with a temporal resolution of 2.1s. Leakage corrected cerebral blood volume (CBV) maps were constructed. 3D-EPSI was acquired using a spin-echo based sequence. EPSI data were processed using metabolic imaging and data analysis system (MIDAS) package. DTI (MD, FA), EPSI [choline (Cho)/creatine(Cr)], CBV maps and FLAIR images were co-registered to post-contrast T1-weighted images and a semi-automated algorithm was used to segment the contrast-enhancing region of neoplasms. Median values of MD, FA, relative CBV (rCBV) and Cho/Cr were computed at each time point. The 90th percentile rCBV (rCBVmax) values were also measured. Percent changes of each parameter between baseline and follow-up time points were evaluated. Results and Discussion: In general, there was an increasing trend in MD (~3%) and steadily decline trend in FA (~8%) at the 2 month follow-up relative to baseline. Additionally, from baseline to post- TTFields, reductions in Cho/Cr and rCBVmax were also observed from most of the patients. Clinically, all these patients were stable at 2 month follow-up. The inhibited cellular growth may account for large increase in MD and decrease in FA and Cho/Cr as observed in the current study. Reducing trends in rCBVmax at the follow-up may indicate anti- angiogenetic effects of TTFields and tissue perfusion within the tumor bed after the therapy. Conclusion: Our preliminary data suggest that advanced MR imaging may be useful in evaluating treatment response to TTFields in patients with GBMs. Inclusion of more patients is warranted to validate our findings. Acknowledgement: Support of NovoTTF-100A system (Novocure Ltd., Haifa, Israel) is gratefully acknowledged. Citation Format: SANJEEV CHAWLA, Sumei Wang, Gaurav Verma, Aaron Skolnik, Lauren Karpf, Lisa Desiderio, Steven Brem, Katherine Peters, Harish Poptani, Suyash Mohan. Tumor treating fields in patients with glioblastomas: Evaluation of treatment response using advanced mr imaging techniques [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT068. doi:10.1158/1538-7445.AM2017-CT068

Predictive Value of Pooled Cerebral Blood Volume Mapping for Final Infarct Volume in Patients with Major Artery Occlusions. ARetrospective Analysis.

Detection of ischemic core and collateral status is helpful to predict clinical success of thrombectomy in acute cerebral artery occlusion. Angiographic flat panel detector computed tomography (CT) with pooled blood volume (PBV) data acquisition was described to be helpful to estimate ischemic core in stroke patients prior to thrombectomy and to depict cerebral vessels. We therefore retrospectively evaluated preinterventional PBV data of alarge collective of ischemic stroke patients prior to thrombectomy to test its predictive value on final infarct considering PBV maps and collateral status. We used PBV data from 101 patients with acute cerebral artery occlusion prior to successful thrombectomy to reconstruct PBV maps and collateral status maps. Suspected ischemic core and collateral status were correlated to final infarct on follow-up multislice CT. Furthermore, the influence of time window and patient age was taken into consideration. In 75.2% (95% confidence interval CI 66-82%), suspected ischemic core (PBV) matched with final infarct and in 24.8% (95% CI 17-34%) final infarct was overestimated. In all patients, collateral status could be evaluated, and the better the collateral status, the smaller the final infarct (p= 0.016). Although not statistically significant, poor collaterals seem to be arisk factor for overestimation of final infarct on PBV maps. In patients >80years old predictive value of PBV and collateral status is better than in patients ≤80years old (p= 0.04). Increasing time window did not have significant impact on predictive value of PBV and collateral status. The PBV data are useful to expeditiously exclude infarct growth and estimate collateral status prior to thrombectomy after alonger interval between initial multislice CT magnetic resonance imaging (MRI) and intervention. However, because of overestimating final infarct in 25% of patients, PBV data presuming large infarct should not be used as the only basis for excluding patients from effective stroke treatment at this point in time.