Abstract 167: Noninvasive MRI Measurement of Cerebrovascular Reactivity Enables Evaluation of Surgical Revascularization Response in Moyamoya

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Travis R Ladner ◽  
Carlos Faraco ◽  
Manus J Donahue ◽  
Daniel Arteaga ◽  
Lori C Jordan ◽  
...  
Keyword(s):  
Tissue Level ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Clinical Severity ◽  
Atmospheric Air ◽  
Bold Mri ◽  
Oxygenation Level ◽  
Hemodynamic Improvement ◽  
Mri Changes ◽  
Mri Measurements

Introduction: Frequent dissociation between clinical severity and angiographic grading of moyamoya supports a role for alternative tissue-level hemodynamic measures. Here, angiography is complemented with noninvasive MRI measurements of parenchymal impairment to assess changes in cerebrovascular reactivity (CVR) after extracranial-intracranial bypass in moyamoya. Hypothesis: CVR is regionally impaired pre-operatively, yet increases after surgery. This can be visualized noninvasively by assessing blood oxygenation level-dependent (BOLD) MRI changes with safe, mildly hypercarbic gas. Methods: Using a block MRI paradigm, carbogen (5% CO 2 ; 95% O 2 3 min) was interleaved with atmospheric air (<1% CO 2 ; 3 min) administration during BOLD MRI in intracranial stenosis patients (n=70), a subset of which (n=9; age=35.7+/-10.8; 7F/2M) underwent indirect (n=8) or direct (n=1) revascularization for moyamoya. Five patients had both pre-operative and post-operative hemodynamic imaging, with post-operative scans performed after 7.3+/-4.1 months. CVR, calculated as a z-statistic in response to hypercarbia vs. atmospheric air, was compared (two-tailed t-test) for each patient between the two time points to correlate CVR changes with surgery. Results: Fig. 1 shows BOLD MRI on a patient scanned before and 2 years after right-sided indirect bypass, with significant (t=79.29, p<0.01) right-sided hemodynamic improvement. Cohort analyses of patients with pre/post-operative scans revealed significant interhemispheric CVR differences prior to surgery (t=3.48, p<0.01), which resolved after bypass (t=0.88, p=0.20). Additionally, CVR increased significantly in the operative hemisphere (t=4.50, p<0.01). Conclusions: CVR-weighted hemodynamic MRI can be implemented into routine clinical protocols, corresponds well with revascularization response, and has potential as a noninvasive complement to angiography for serial monitoring of moyamoya patients.

scholarly journals The Cumulative Influence of Hyperoxia and Hypercapnia on Blood Oxygenation and R2*

2015 ◽  
Vol 35 (12) ◽  
pp. 2032-2042 ◽  
Author(s):  
Carlos C Faraco ◽  
Megan K Strother ◽  
Jeroen CW Siero ◽  
Daniel F Arteaga ◽  
Allison O Scott ◽  
...  
Keyword(s):  
Venous Blood ◽  
Quantitative Information ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Resonance Imaging ◽  
Tissue Water ◽  
Bold Mri ◽  
Bold Imaging ◽  
Complex Interactions ◽  
Oxygenation Level

Cerebrovascular reactivity (CVR)-weighted blood-oxygenation-level-dependent magnetic resonance imaging (BOLD-MRI) experiments are frequently used in conjunction with hyperoxia. Owing to complex interactions between hyperoxia and hypercapnia, quantitative effects of these gas mixtures on BOLD responses, blood and tissue R2∗, and blood oxygenation are incompletely understood. Here we performed BOLD imaging (3T; TE/TR = 35/2,000 ms; spatial resolution = 3×3×3.5 mm3) in healthy volunteers ( n = 12; age = 29±4.1 years) breathing (i) room air (RA), (ii) normocapnic-hyperoxia (95% O2/5% N2, HO), (iii) hypercapnic-normoxia (5% CO2/21% O2/74% N2, HC-NO), and (iv) hypercapnic-hyperoxia (5% CO2/95% O2, HC-HO). For HC-HO, experiments were performed with separate RA and HO baselines to control for changes in O2. T2-relaxation-under-spin-tagging MRI was used to calculate basal venous oxygenation. Signal changes were quantified and established hemodynamic models were applied to quantify vasoactive blood oxygenation, blood–water R∗2, and tissue-water R∗2. In the cortex, fractional BOLD changes (stimulus/baseline) were HO/RA = 0.011 ± 0.007; HC-NO/RA = 0.014±0.004; HC-HO/HO = 0.020±0.008; and HC-HO/RA = 0.035 ±0.010; for the measured basal venous oxygenation level of 0.632, this led to venous blood oxygenation levels of 0.660 (HO), 0.665 (HC-NO), and 0.712 (HC-HO). Interleaving a HC-HO stimulus with HO baseline provided a smaller but significantly elevated BOLD response compared with a HC-NO stimulus. Results provide an outline for how blood oxygenation differs for several gas stimuli and provides quantitative information on how hypercapnic BOLD CVR and R∗2 are altered during hyperoxia.

Impact of baseline CO 2 on Blood-Oxygenation-Level-Dependent MRI measurements of cerebrovascular reactivity and task-evoked signal activation

2018 ◽  
Vol 49 ◽  
pp. 123-130 ◽  
Author(s):  
Christiaan Hendrik Bas van Niftrik ◽  
Marco Piccirelli ◽  
Oliver Bozinov ◽  
Nicolai Maldaner ◽  
Catherine Strittmatter ◽  
...  
Keyword(s):  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Blood Oxygenation Level ◽  
Oxygenation Level ◽  
Mri Measurements ◽  
Signal Activation ◽  
And Task

scholarly journals Feasibility and safety of intraoperative BOLD functional MRI cerebrovascular reactivity to evaluate extracranial-to-intracranial bypass efficacy

2019 ◽  
Vol 46 (2) ◽  
pp. E7 ◽  
Author(s):  
Giovanni Muscas ◽  
Christiaan Hendrik Bas van Niftrik ◽  
Jorn Fierstra ◽  
Marco Piccirelli ◽  
Martina Sebök ◽  
...  
Keyword(s):  
Brain Tissue ◽  
Functional Mri ◽  
Bypass Graft ◽  
Tissue Level ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Bypass Flow ◽  
Hemodynamic Changes ◽  
Flow Measurements ◽  
Oxygenation Level

Blood oxygenation level–dependent functional MRI cerebrovascular reactivity (BOLD-CVR) is a contemporary technique to assess brain tissue hemodynamic changes after extracranial- intracranial (EC-IC) bypass flow augmentation surgery. The authors conducted a preliminary study to investigate the feasibility and safety of intraoperative 3-T MRI BOLD-CVR after EC-IC bypass flow augmentation surgery. Five consecutive patients selected for EC-IC bypass revascularization underwent an intraoperative BOLD-CVR examination to assess early hemodynamic changes after revascularization and to confirm the safety of this technique. All patients had a normal postoperative course, and none of the patients exhibited complications or radiological alterations related to prolonged anesthesia time. In addition to intraoperative flow measurements of the bypass graft, BOLD-CVR maps added information on the hemodynamic status and changes at the brain tissue level. Intraoperative BOLD-CVR is feasible and safe in patients undergoing EC-IC bypass revascularization. This technique can offer immediate hemodynamic feedback on brain tissue revascularization after bypass flow augmentation surgery.

scholarly journals Hemodynamic and metabolic changes during hypercapnia with normoxia and hyperoxia using pCASL and TRUST MRI in healthy adults

2021 ◽  
pp. 0271678X2110645
Author(s):  
Pieter T Deckers ◽  
Alex A Bhogal ◽  
Mathijs BJ Dijsselhof ◽  
Carlos C Faraco ◽  
Peiying Liu ◽  
...  
Keyword(s):  
Arterial Spin Labeling ◽  
Oxygen Metabolism ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Oxygen Extraction Fraction ◽  
Mixed Effect ◽  
Cerebral Oxygen Metabolism ◽  
Extraction Fraction ◽  
Oxygenation Level

Blood oxygenation level-dependent (BOLD) or arterial spin labeling (ASL) MRI with hypercapnic stimuli allow for measuring cerebrovascular reactivity (CVR). Hypercapnic stimuli are also employed in calibrated BOLD functional MRI for quantifying neuronally-evoked changes in cerebral oxygen metabolism (CMRO2). It is often assumed that hypercapnic stimuli (with or without hyperoxia) are iso-metabolic; increasing arterial CO2 or O2 does not affect CMRO2. We evaluated the null hypothesis that two common hypercapnic stimuli, ‘CO2 in air’ and carbogen, are iso-metabolic. TRUST and ASL MRI were used to measure the cerebral venous oxygenation and cerebral blood flow (CBF), from which the oxygen extraction fraction (OEF) and CMRO2 were calculated for room-air, ‘CO2 in air’ and carbogen. As expected, CBF significantly increased (9.9% ± 9.3% and 12.1% ± 8.8% for ‘CO2 in air’ and carbogen, respectively). CMRO2 decreased for ‘CO2 in air’ (−13.4% ± 13.0%, p < 0.01) compared to room-air, while the CMRO2 during carbogen did not significantly change. Our findings indicate that ‘CO2 in air’ is not iso-metabolic, while carbogen appears to elicit a mixed effect; the CMRO2 reduction during hypercapnia is mitigated when including hyperoxia. These findings can be important for interpreting measurements using hypercapnic or hypercapnic-hyperoxic (carbogen) stimuli.

scholarly journals BOLD MRI to evaluate early development of renal injury in a rat model of diabetes

2018 ◽  
Vol 46 (4) ◽  
pp. 1391-1403 ◽  
Author(s):  
Qidong Wang ◽  
Chuangen Guo ◽  
Lan Zhang ◽  
Rui Zhang ◽  
Zhaoming Wang ◽  
...  
Keyword(s):  
Renal Injury ◽  
Diabetic Rats ◽  
Blood Oxygenation ◽  
Dynamic Changes ◽  
Bold Mri ◽  
Oxygenation Level ◽  
Mri Scans ◽  
Streptozotocin Induced Diabetes ◽  
Magnetic Resonance Imaging Mri ◽  
Diabetes Induction

Objective To investigate changes in renal oxygenation levels by blood-oxygenation-level dependent (BOLD)-magnetic resonance imaging (MRI), and to evaluate BOLD-MRI for detecting early diabetic renal injury. Methods Seventy-five rats, with unilateral nephrectomy, were randomly divided into streptozotocin-induced diabetes mellitus (DM, n = 65) and normal control (NC, n = 10) groups. BOLD-MRI scans were performed at baseline (both groups) and at 3, 7, 14, 21, 28, 35, 42, 49, 56, 63 and 70 days (DM only). Renal cortical (C) and medullary (M) R2* signals were measured and R2* medulla/cortex ratio (MCR) was calculated. Results DM-group CR2* and MR2* values were significantly higher than NC values following diabetes induction. R2* values increased gradually and peaked at day 35 (CR2*, 33.95 ± 0.34 s–1; MR2*, 43.79 ± 1.46 s–1), then dropped gradually (CR2*, 33.17 ± 0.69 s–1; MR2*, 41.61 ± 0.95 s–1 at day 70). DM-group MCR rose gradually from 1.12 to 1.32 at day 42, then decreased to 1.25 by day 70. Conclusions BOLD-MRI can be used to non-invasively evaluate renal hypoxia and early diabetic renal injury in diabetic rats. MCR may be adopted to reflect dynamic changes in renal hypoxia.

scholarly journals Hemodynamic investigation of peritumoral impaired blood oxygenation-level dependent cerebrovascular reactivity in patients with diffuse glioma

2020 ◽  
Vol 70 ◽  
pp. 50-56
Author(s):  
Giovanni Muscas ◽  
Christiaan Hendrik Bas van Niftrik ◽  
Martina Sebök ◽  
Katharina Seystahl ◽  
Marco Piccirelli ◽  
...  
Keyword(s):  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Diffuse Glioma ◽  
Blood Oxygenation Level ◽  
Oxygenation Level

scholarly journals The Vascular Steal Phenomenon is an Incomplete Contributor to Negative Cerebrovascular Reactivity in Patients with Symptomatic Intracranial Stenosis

2014 ◽  
Vol 34 (9) ◽  
pp. 1453-1462 ◽  
Author(s):  
Daniel F Arteaga ◽  
Megan K Strother ◽  
Carlos C Faraco ◽  
Lori C Jordan ◽  
Travis R Ladner ◽  
...  
Keyword(s):  
Clinical Symptoms ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Intracranial Stenosis ◽  
Compensatory Mechanism ◽  
Ischemic Cerebrovascular Disease ◽  
Oxygenation Level ◽  
Fluid Attenuated Inversion Recovery ◽  
Vascular Steal ◽  
Negative Bold

‘Vascular steal’ has been proposed as a compensatory mechanism in hemodynamically compromised ischemic parenchyma. Here, independent measures of cerebral blood flow (CBF) and blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) responses to a vascular stimulus in patients with ischemic cerebrovascular disease are recorded. Symptomatic intracranial stenosis patients ( n = 40) underwent a multimodal 3.0T MRI protocol including structural (T1-weighted and T2-weighted fluid-attenuated inversion recovery) and hemodynamic (BOLD and CBF-weighted arterial spin labeling) functional MRI during room air and hypercarbic gas administration. CBF changes in regions demonstrating negative BOLD reactivity were recorded, as well as clinical correlates including symptomatic hemisphere by infarct and lateralizing symptoms. Fifteen out of forty participants exhibited negative BOLD reactivity. Of these, a positive relationship was found between BOLD and CBF reactivity in unaffected (stenosis degree <50%) cortex. In negative BOLD cerebrovascular reactivity regions, three patients exhibited significant ( P < 0.01) reductions in CBF consistent with vascular steal; six exhibited increases in CBF; and the remaining exhibited no statistical change in CBF. Secondary findings were that negative BOLD reactivity correlated with symptomatic hemisphere by lateralizing clinical symptoms and prior infarcts(s). These data support the conclusion that negative hypercarbia-induced BOLD responses, frequently assigned to vascular steal, are heterogeneous in origin with possible contributions from autoregulation and/or metabolism.

Abstract 2240: T2-Prepared Steady-State Free-Precession Blood Oxygenation Level-Dependent MRI in Patients with Coronary Artery Disease and Normal Volunteers: Validation against PET

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Theodoros D Karamitsos ◽  
Alejandro Recio-Mayoral ◽  
Jayanth R Arnold ◽  
Lucia Leccisotti ◽  
Paul Bhamra-Ariza ◽  
...  
Keyword(s):  
Gold Standard ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Short Axis ◽  
Normal Volunteers ◽  
Bold Mri ◽  
Blood Oxygenation Level ◽  
Oxygenation Level ◽  
Artery Disease ◽  
Perfusion Measurements

Blood oxygenation level-dependent (BOLD) MRI clinical studies at 1.5 Tesla (T) have been principally limited by low signal to noise. We sought to apply this method at 3T in patients with coronary artery disease (CAD) and normal volunteers, and validated it against perfusion measurements by PET. Twenty-two patients (age 62±8 yrs, 16 men) with CAD (at least 1 stenosis > 50% on quantitative coronary angiography-QCA) and 10 normal volunteers (age 52±7 yrs, 7 men) underwent 3T BOLD MRI and PET. For BOLD MRI a mid-ventricular slice was acquired every 30sec at rest and during adenosine stress (140 μg/kg/min). A set of 6 images was acquired at rest and at peak stress. Using PET with oxygen-15 labelled water, myocardial blood flow (MBF) was measured at baseline and during adenosine hyperemia. The BOLD short-axis view was divided into 6 segments, according to the mid-ventricular segments of the 17-AHA segment model, and mean signal intensities (SI) were calculated using QMass (Medis) software. PET images were analyzed with MATLAB software (MathWorks Inc.) and registered with the BOLD short-axis image using anatomical landmarks. Taking QCA as the gold standard, cut-off values for stress MBF (< 2.57ml/min/g - AUC 0.79) and BOLD SI change (< 4.75% -AUC 0.78) were determined to define ischemic segments. Rest MBF, stress MBF, coronary flow reserve and BOLD-SI change of ischemic (n=69), remote to ischemia (n=73) and normal segments (n=60) are shown in table . BOLD MRI and PET agreed on the presence or absence of ischemia in 18 of the 22 patients (82%), and in all normals. With regards to per segment analysis: taking PET as the gold standard and by applying the cut-off values for stress MBF and BOLD SI, BOLD MRI had only moderate sensitivity (61%) but good specificity (88%) for the identification of ischemia. T2-prepared SSFP 3T BOLD imaging is feasible in the clinical setting and has good agreement with PET perfusion measurements for the detection of myocardial ischemia.

Blood oxygenation level-dependent MRI at 3T for differentiating prostate cancer from benign tissue: a preliminary experience

2021 ◽  
pp. 20210461
Author(s):  
Yongtae Kim ◽  
Jung Jae Park ◽  
Chan Kyo Kim
Keyword(s):  
Prostate Cancer ◽  
Regional Distribution ◽  
Specific Antigen ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Bold Mri ◽  
Benign Tissue ◽  
Blood Oxygenation Level ◽  
Oxygenation Level ◽  
Mean Differences

Objective: Blood oxygenation-level dependent (BOLD) MRI may identify or quantify the regional distribution of hypoxia within a tumor. We aimed to evaluate the feasibility of BOLD MRI at 3 T in differentiating prostate cancer from benign tissue. Methods: A total of 145 patients with biopsy-proven prostate cancer underwent BOLD MRI at 3 T. BOLD MRI was performed using a multiple fast field echo sequence to acquire 12 T2*-weighted images. The R2* value (rate of relaxation, s−1) was measured in the index tumor, and benign peripheral (PZ) and transition zone (TZ), and the results were compared. The variability of R2* measurements was evaluated. Results: Tumor R2* values (25.95 s−1) were significantly different from the benign PZ (27.83 s−1) and benign TZ (21.66 s−1) (p < 0.001). For identifying the tumor, the area under the receiver operating characteristic of R2* was 0.606, with an optimal cut-off value of 22.8 s−1 resulting in 73.8% sensitivity and 52% specificity. In the Bland–Altman test, the mean differences in R2* values were 8.5% for tumors, 13.3% for benign PZ, and 6.8% for benign TZ. No associations between tumor R2* value and Gleason score, age, prostate volume, prostate-specific antigen, or tumor size. Conclusion: BOLD MRI at 3 T appears to be a feasible tool for differentiating between prostate cancer and benign tissue. However, further studies are required for a direct clinical application. Advances in knowledge: The R2* values are significantly different among prostate cancer, benign PZ, and benign TZ.

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