Gradient-recalled Echo MRI Research Articles

Comparison of Hemorrhage on CT Versus MRI After Thrombectomy: The HECATE Study

Background The characterization of hemorrhage following acute stroke intervention has largely been computed tomography (CT) based. We sought to compare magnetic resonance imaging‐ (MRI‐) and CT‐based scoring of hemorrhage after acute endovascular therapy (EVT) applying the Heidelberg Bleeding Classification (HBC) to assess intermodal agreement and quantify interrater agreement. Methods Consecutive patients with acute stroke were included in this retrospective study if they (1) had MRI and CT ≤12 hours of each other OR (2) had CT bracketed by MRI pre‐ and post‐CT (ie, MRI‐CT‐MRI) ≤7 days post‐EVT. The concordance of the HBC ratings by consensus panel were compared between CT and T2 * gradient recalled echo MRI. Results For the 87 EVT‐treated patients included, median age was 68 years [60–74], admission National Institutes of Health Stroke Scale score 18 [13–23], 47% were treated with intravenous/intraarterial thrombolytics, and 93% were successfully recanalized (modified Thrombolysis in Cerebral Infarction 2b/3). Hemorrhage was detected on at least 1 modality in 60% (52/87) of patients. We found a 68% (59/87, 95% CI [57%–77%]) agreement overall between CT and MRI for hemorrhage classification post‐EVT. MRI had the best interrater agreement for HBC 0 (no hemorrhage) with excellent concordance (ĸ = 0.882), compared with CT (ĸ = 0.683). T2 * gradient recalled echo MRI tended to have increased sensitivity to scattered petechial hemorrhage (HBC 1a) as compared with CT with 17% (2/12) intermodal agreement. The interrater agreement of HBC class 2 (ie, parenchymal hematoma grade 2 was substantial for MRI (ĸ = 0.781) and excellent in CT (ĸ = 0.951), with 67% (8/12) intermodal agreement. Subarachnoid hemorrhage was detected in 24% (21/87) of patients on CT and/or MRI with 29% (6/21) intermodal agreement. Conclusion With the exception of subarachnoid hemorrhage and minor petechial hemorrhagic transformation, we found that MRI and CT are overall interchangeable for detecting and classifying hemorrhage after EVT. These findings are reassuring for both clinical decision‐making and research application. Given the complexity of hemorrhage subtypes post‐EVT, work to further refine a post‐EVT hemorrhage classification scale with clinical correlation would be beneficial.

Increased periventricular thalamic damage gradient in multiple sclerosis detected by quantitative gradient echo MRI

ObjectiveThalamic tissue damage in multiple sclerosis (MS) follows a ‘surface-in’ gradient from the ventricular surface. The clinical consequences of this gradient are not completely understood. Using quantitative gradient-recalled echo (qGRE) MRI, we evaluated a periventricular thalamic gradient of tissue integrity in MS and its relationship with clinical variables. MethodsStructural and qGRE MRI scans were acquired for a cohort of MS patients and healthy controls (HC). qGRE-derived R2t* values were used as a measure of tissue integrity. Thalamic segmentations were divided into 1-mm concentric bands radiating from the ventricular surface, excluding the CSF-adjacent band. Median R2t* values within these bands were used to calculate the periventricular thalamic gradient. ResultsWe included 44 MS patients and 17 HC. R2t* increased slightly with distance from the ventricular surface in HC. MS patients had a steeper periventricular thalamic gradient compared to HC (mean slope 0.55 vs. 0.36; p < 0.001), which correlated with longer disease duration (β = 0.001 /year; p = 0.027) and higher Expanded Disability Status Scale (EDSS) score (β = 0.07 /EDSS point; p = 0.019). Left and right thalamus were symmetrically affected. ConclusionsWe detected an increased thalamic gradient in MS in vivo using qGRE MRI, which correlated with disease duration and greater clinical disability. These findings further support the ‘surface-in’ pathology hypothesis in MS and suggest a CSF-mediated process given symmetric bi-thalamic involvement.

Deep learning-based Accelerated and Noise-Suppressed Estimation (DANSE) of quantitative Gradient-Recalled Echo (qGRE) magnetic resonance imaging metrics associated with human brain neuronal structure and hemodynamic properties.

The purpose of the current study was to introduce a Deep learning-based Accelerated and Noise-Suppressed Estimation (DANSE) method for reconstructing quantitative maps of biological tissue cellular-specific, R2t*, and hemodynamic-specific, R2', metrics of quantitative gradient-recalled echo (qGRE) MRI. The DANSE method adapts a supervised learning paradigm to train a convolutional neural network for robust estimation of R2t* and R2' maps with significantly reduced sensitivity to noise and the adverse effects of macroscopic (B0 ) magnetic field inhomogeneities directly from the gradient-recalled echo (GRE) magnitude images. The R2t* and R2' maps for training were generated by means of a voxel-by-voxel fitting of a previously developed biophysical quantitative qGRE model accounting for tissue, hemodynamic, and B0 -inhomogeneities contributions to multigradient-echo GRE signal using a nonlinear least squares (NLLS) algorithm. We show that the DANSE model efficiently estimates the aforementioned qGRE maps and preserves all the features of the NLLS approach with significant improvements including noise suppression and computation speed (from many hours to seconds). The noise-suppression feature of DANSE is especially prominent for data with low signal-to-noise ratio (SNR ~ 50-100), where DANSE-generated R2t* and R2' maps had up to three times smaller errors than that of the NLLS method. The DANSE method enables fast reconstruction of qGRE maps with significantly reduced sensitivity to noise and magnetic field inhomogeneities. The DANSE method does not require any information about field inhomogeneities during application. It exploits spatial and gradient echo time-dependent patterns in the GRE data and previously gained knowledge from the biophysical model, thus producing high quality qGRE maps, even in environments with high noise levels. These features along with fast computational speed can lead to broad qGRE clinical and research applications.

Abstract WP23: Determining The Association Between Atrial Cardiopathy And Cerebral Microbleeds In Ischemic Stroke Patients

Introduction: Cerebral microbleeds (CMB) are frequently found in individuals with atrial fibrillation (AF) or ischemic stroke (IS), but whether atrial cardiopathy among IS patients is associated with CMB is unknown. We hypothesize that atrial cardiopathy is associated with increased risk of CMB. Methods: Inclusion criteria were IS patients admitted to Johns Hopkins (2015-2019) with transthoracic echocardiography, and electrocardiography. CMB were defined per established criteria as small, round hypo-intensities on T2* susceptibility weighted imaging or gradient recalled echo MRI sequences. Atrial cardiopathy was defined as the presence of ≥1: left atrium (LA) diameter &gt;4.0 cm (males) or &gt;3.8 cm (females), PR interval &gt;200 ms, or NT-pro BNP &gt;250 pg/mL. Multivariable or multinomial logistic regression was used to determine the association between atrial cardiopathy, and CMB presence or number, each, adjusted for potential confounders. Results: Patients (N=150) were mean age 61 years (range 22-98), 42% female, 59% black, and 42% were on anti-thrombotic medications. 54 (36%) participants had ≥1 CMB (range 0-10, IQR 0-7). 65 (43%) patients had atrial cardiopathy (46 with enlarged LA diameter, 15 with elongated PR interval, 16 with elevated NT-pro BNP). Age (67 years vs. 57 years, p&lt;0.001) and AF (N=18 vs. N=12, p=0.032) differed based on atrial cardiopathy status. Atrial cardiopathy was associated with higher odds of any CMB (OR 2.41, 95% CI 1.22-4.79) but not after adjustment (Table 1). Atrial cardiopathy was associated with lobar CMB (OR 2.33, 95% CI 1.01-5.37, Model 3) but not with deep (OR 0.45, 95% CI 0.13-1.54, Model 3). There was a non-statistically significant higher relative risk of having 1 or &gt;1 CMBs (vs. none) among those with atrial cardiopathy. Conclusion: In this study, we found a significant association between atrial cardiopathy and lobar CMB in IS patients, suggesting that atrial cardiopathy may increase subclinical embolic risk.

The Role of the Human Brain Neuron-Glia-Synapse Composition in Forming Resting-State Functional Connectivity Networks.

While significant progress has been achieved in studying resting-state functional networks in a healthy human brain and in a wide range of clinical conditions, many questions related to their relationship to the brain’s cellular constituents remain. Here, we use quantitative Gradient-Recalled Echo (qGRE) MRI for mapping the human brain cellular composition and BOLD (blood–oxygen level-dependent) MRI to explore how the brain cellular constituents relate to resting-state functional networks. Results show that the BOLD signal-defined synchrony of connections between cellular circuits in network-defined individual functional units is mainly associated with the regional neuronal density, while the between-functional units’ connectivity strength is also influenced by the glia and synaptic components of brain tissue cellular constituents. These mechanisms lead to a rather broad distribution of resting-state functional network properties. Visual networks with the highest neuronal density (but lowest density of glial cells and synapses) exhibit the strongest coherence of the BOLD signal as well as the strongest intra-network connectivity. The Default Mode Network (DMN) is positioned near the opposite part of the spectrum with relatively low coherence of the BOLD signal but with a remarkably balanced cellular contents, enabling DMN to have a prominent role in the overall organization of the brain and hierarchy of functional networks.

MRI quantitative susceptibility mapping of the substantia nigra as an early biomarker for Lewy body disease.

Neurodegeneration of the substantia nigra in Lewy body disease is associated with iron deposition, which increases the magnetic susceptibility of the substantia nigra on MRI. Our objective was to measure iron deposition in the substantia nigra in patients with probable dementia with Lewy bodies (pDLB) and patients who are at risk for pDLB by quantitative susceptibility mapping (QSM). Participants included pDLB (n = 36), mild cognitive impairment with at least one core feature of DLB (MCI-LB; n = 15), idiopathic rapid eye movement sleep behavior disorder (iRBD; n = 11), and an age-and gender-matched clinically unimpaired control group (n = 102). QSM was derived from multi-echo 3D gradient recalled echo MRI at 3T, and groups were compared on mean susceptibility values of the substantia nigra and its relation to parkinsonism severity. Patients with pDLB had higher susceptibility in the substantia nigra compared to controls (p< 0.001) and MCI-LB (p = 0.043). The susceptibility of substantia nigra showed an increasing trend from controls to iRBD and MCI-LB, and to pDLB (p< 0.001). Parkinsonism severity was not associated with the mean susceptibility in the substantia nigra in the patient groups. Our data suggested that QSM is sensitive to the increased magnetic susceptibility due to higher iron content in the substantia nigra in pDLB. The trend of increasing susceptibility from controls to iRBD and MCI-LB, and to pDLB suggests that iron deposition in the substantia nigra starts to increase as early as the prodromal stage in DLB and continues to increase as the disease progresses, independent of parkinsonism severity.

Evaluation of the changes in hepatic apparent diffusion coefficient and hepatic fat fraction in healthy cats during body weight gain.

To determine the change in mean hepatic apparent diffusion coefficient (ADC) and hepatic fat fraction (HFF) during body weight gain in cats by use of MRI. 12 purpose-bred adult neutered male cats. The cats underwent general health and MRI examination at time 0 (before dietary intervention) and time 1 (after 40 weeks of being fed high-energy food ad libitum). Sequences included multiple-echo gradient-recalled echo MRI and diffusion-weighted MRI with 3 b values (0, 400, and 800 s/mm2). Variables (body weight and the HFF and ADC in selected regions of interest in the liver parenchyma) were compared between time points by Wilcoxon paired-sample tests. Relationships among variables were assessed with generalized mixed-effects models. Median body weight was 4.5 and 6.5 kg, mean ± SD HFF was 3.39 ± 0.89% and 5.37 ± 1.92%, and mean ± SD hepatic ADC was 1.21 ± 0.08 × 10-3 mm2/s and 1.01 ± 0.2 × 10-3 mm2/s at times 0 and 1, respectively. Significant differences between time points were found for body weight, HFF, and ADC. The HFF was positively associated with body weight and ADC was negatively associated with HFF. Similar to findings in people, cats had decreasing hepatic ADC as HFF increased. Protons associated with fat tissue in the liver may reduce diffusivity, resulting in a lower ADC than in liver with lower HFF. Longer studies and evaluation of cats with different nutritional states are necessary to further investigate these findings.

MRI phase offset correction method impacts quantitative susceptibility mapping

Individual channel ultra-high field (7T) phase images have to be phase offset corrected prior to the mapping of magnetic susceptibility of tissue. Whilst numerous methods have been proposed for gradient recalled echo MRI phase offset correction, it remains unclear how they affect quantitative magnetic susceptibility values derived from phase images. Methods already proposed either employ a single or multiple echo time MRI data. In terms of the latter, offsets can be derived using an ultra-short echo time acquisition, or by estimating the offset based on two echo points with the assumption of linear phase evolution with echo time. Our evaluation involved 32 channel multi-echo time 7T GRE (Gradient Recalled Echo) and ultra-short echo time PETRA (Pointwise Encoding Time Reduction with Radial Acquisition) MRI data collected for a susceptibility phantom and three human brains. The combined phase images generated using four established offset correction methods (two single and two multiple echo time) were analysed, followed by an assessment of quantitative susceptibility values obtained for a phantom and human brains. The effectiveness of each method in removing the offsets was shown to reduce with increased echo time, decreased signal intensity and reduced overlap in coil sensitivity profiles. Quantitative susceptibility values and how they change with echo time were found to be method specific. Phase offset correction methods based on single echo time data have a tendency to produce more accurate and less noisy quantitative susceptibility maps in comparison with methods employing multiple echo time data.

Field strength influences on gradient recalled echo MRI signal compartment frequency shifts

Different trends of echo time dependent gradient recalled echo MRI signals in different brain regions have been attributed to signal compartments in image voxels. It remains unclear how variations in gradient recalled echo MRI signals change as a function of MRI field strength, and how data processing may impact signal compartment parameters. We used two popular quantitative susceptibility mapping methods of processing raw phase images (Laplacian and path-based unwrapping with V-SHARP) and expressed values in the form of induced frequency shifts (in Hz) in six specific brain regions at 3T and 7T. We found the frequency shift curves to vary with echo time, and a good overlap between 3T and 7T mean frequency shift curves was present. However, the amount of variation across participants was greater at 3T, and we were able to obtain better compartment model fits of the signal at 7T. We also found the temporal trends in the signal and compartment frequency shifts to change with the method used to process images. The inter-participant averaged trends were consistent between 3T and 7T for each quantitative susceptibility pipeline. However, signal compartment frequency shifts generated using different pipelines may not be comparable.

Cerebral amyloid angiopathy-related transient focal neurological episodes: A transient ischemic attack mimic with an increased risk of intracranial hemorrhage

BackgroundTransient focal neurological episodes (TFNEs) are a recently recognized clinical presentation of cerebral amyloid angiopathy (CAA). Our aim was to describe the clinical and radiological features of a series of patients with AS. MethodsWe included 11 patients presenting with recurrent transient focal neurological symptoms and radiological features related to CAA. ResultsMean age was 76,6 and 5 patients were women. All patients reported transient, stereotyped, and recurrent episodes (6 patients had >10 episodes). Gradual spread of the symptoms was recorded in 9 patients. Initially, 3 patients were misdiagnosed as having recurrent transient ischemic attack (TIA), 6 as having seizures, and 2 as having both. Two patients were prescribed antiplatelet therapy. A cerebral MRI with T2* gradient-recalled echo sequence revealed cortical superficial siderosis (cSS) in 5 patients, cortical microbleeds in 1 patient, and both features in 5 cases. After a median follow-up of 36 months, intracranial hemorrhage (ICH) was recorded in 4 patients. All 4 had cSS in the previous cerebral MRI, and 1 was on antiplatelet therapy. ConclusionCAA-related TFNEs are an underdiagnosed entity, often mimicking TIA, seizures, or migraine aura. This misdiagnosis can lead to the prescription of antiplatelet or anticoagulant therapy, which increases the risk of ICH. Our results suggest that cSS might be a radiological marker that is closely related to an increased risk of bleeding. A T2* gradient-recalled echo MRI should be performed in elderly patients with transient focal neurological symptoms suggestive of CAA.

7T GRE-MRI signal compartments are sensitive to dysplastic tissue in focal epilepsy

Ultra-high field magnetic resonance imaging data obtained using a multi-echo gradient echo sequence has been shown to contain information on tissue microstructure. Quantitative assessment of water fraction, relaxation time and frequency shift using multi-compartment signal modelling may help improve our understanding of diseases and disorders affecting the human brain. In this study, we explored tissue microstructure information by analysing voxel compartment water fraction and frequency shifts derived from 7 T multi-echo gradient recalled echo MRI data. We aimed to test whether the parameters of a three compartment model could distinguish the normal cortex from the cortex affected by focal cortical dysplasia. We compartmentalised normal and dysplastic cortical regions in patients diagnosed with focal cortical dysplasia. We found the frequency shift parameter of the shortest T2⁎ signal compartment to be sensitive to regions of dysplastic tissue. We conclude that mathematical modelling of echo time dependent gradient recalled echo MRI signals in patients with focal cortical dysplasia can potentially delineate cortical areas that have undergone microstructural changes in comparison to normal tissue.

Single scan quantitative gradient recalled echo MRI for evaluation of tissue damage in lesions and normal appearing gray and white matter in multiple sclerosis.

Multiple sclerosis (MS) is a chronic disease affecting the human central nervous system (CNS) and leading to neurologic disability. Although conventional MRI techniques can readily detect focal white matter (WM) lesions, it remains challenging to quantify tissue damage in normal-appearing gray matter (GM) and WM. To demonstrate that a new MRI biomarker, R2t*, can provide quantitative analysis of tissue damage across the brain in MS patients in a single scan. Prospective. Forty-four MS patients and 19 healthy controls (HC). 3T, quantitative gradient-recalled-echo (qGRE), Magnetization-prepared rapid gradient-echo, fluid-attenuated inversion recovery. Severity of tissue damage was assessed by reduced R2t*. Tissue atrophy was assessed by cortical thickness and cervical spinal cord cross-sectional area (CSA). Multiple Sclerosis Functional Composite was used for clinical assessment. R2t* in cortical GM was more sensitive to MS damage than cortical atrophy. Using more than two standard deviations (SD) reduction versus age-matched HC as the cutoff, 48% of MS patients showed lower R2t*, versus only 9% with lower cortical thickness. Significant correlations between severities of tissue injury were identified among 1) upper cervical cord and several cortical regions, including motor cortex (P < 0.001), and 2) adjacent regions of GM and subcortical WM (P < 0.001). R2t*-defined tissue cellular damage in cortical GM was greater relative to adjacent WM. Reductions in cortical R2t* correlated with cognitive impairment (P < 0.01). Motor-related clinical signs correlated most with cervical cord CSA (P < 0.001). Reductions in R2t* within cortical GM was more sensitive to tissue damage than atrophy, potentially allowing a reduced sample size in clinical trials. R2t* together with structural morphometry suggested topographic patterns of regions showing correlated tissue damage throughout the brain and the cervical spinal cord of MS patients. 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;49:487-498.

MRI Detection of Intratumoral Fat in Colorectal Liver Metastases After Preoperative Chemotherapy.

The objective of this study was to investigate the incidence and clinical significance of intratumoral fat deposition in colorectal liver metastases (CLMs) after preoperative chemotherapy using dual-echo gradient-recalled echo MRI. Our institutional review board approved this retrospective radiographic study and waived the requirement for informed patient consent. Fifty-nine patients (33 men, 26 women; median age, 62 years old) who underwent preoperative MRI and curative hepatic resection for colorectal liver metastases after chemotherapy were selected. Twenty patients also underwent MRI before chemotherapy. On dual-echo gradient-recalled echo MR images, intratumoral fat deposition and fat signal fraction at the densest areas of fat deposition in colorectal liver metastases were evaluated. Predictors of overall survival and intratumoral fat deposition after chemotherapy were identified by multivariate analyses. Before and after chemotherapy, 0 (0%) and 32 (54%) of the patients exhibited intratumoral fat deposition, respectively. Independent predictors of poor overall survival were presence of five or more CLMs (p < 0.001), fat signal fraction of 12% or more (p = 0.01), age of 65 years or older (p = 0.02), and tumor response classified as progressive or stable disease by the Response Evaluation Criteria in Solid Tumors 1.1 (p = 0.049). Predictors of tumor fat signal fraction being 12% or greater after chemotherapy were largest tumor size of 5 cm or more (p = 0.005), tumor calcification (p = 0.008), and history of cetuximab or panitumumab administration (p = 0.04). CLMs after preoperative chemotherapy frequently exhibit intratumoral fat deposition.

MRI-detected subchondral bone marrow lesions: does using two mri sequences improve detection and clinical relevance?

Purpose: Fluid-sensitive MRIs are preferred in scoring BMLs compared to gradient recalled echo (GRE)-type MRI sequences. However, whether one sequence correlates better with clinical osteoarthritis (OA) outcomes than the other is unknown. We aim to describe the association of bone marrow lesions (BMLs) present on two different MRI sequences with pain, physical function limitation, stiffness, cartilage defect progression, cartilage volume loss over 2.7 years, and total knee replacement (TKR) over 13.3 years in older adults. Methods: 394 community-dwelling adults aged 50–80 years were assessed at baseline and 2.7 years. BML presence at baseline was scored on T1-weighted fat-suppressed 3D gradient-recalled acquisition (T1-w GRE) and T2-weighted fat-suppressed 2D fast spin-echo (T2-w FSE) MRI sequences, at the tibial, femoral, and patellar sites. Knee pain, physical function limitation, and stiffness were assessed using Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scales. Cartilage volume and defect scores were assessed using validated methods. The incidence of TKR was determined by data linkage to the Australian Orthopaedic Association National Joint Replacement Registry. Ordinal logistic, linear, log binomial, and mixed-effects regression were used for analysis. Results: BMLs were mostly present on both MRI sequences (86%) and appeared slightly larger on T2-w FSE MRI. BMLs present on T2-w FSE, T1-w GRE, and both MRI sequences were associated with increased odds of moving to a higher category of knee pain and physical function limitation (odds ratio (OR) = 1.49 to 1.70; all P < 0.05) but not stiffness. Longitudinally, BMLs present on T2-w FSE, T1-w GRE, and both MRI sequences were associated with worsening knee pain (β = 1.12 to 1.37, respectively; P < 0.05) and worsening stiffness (β = 0.45 to 0.52, respectively; all P < 0.05) but not worsening physical function limitation or total WOMAC. BMLs present on T2-w FSE, T1-w GRE, and both MRI sequences predicted site-specific cartilage defect progression (relative risk (RR) = 1.22 to 4.63; all P < 0.05) except at the medial tibial and inferior patellar sites. Lateral tibial and superior patellar BMLs present on T2-w FSE, T1-w GRE, and both MRI sequences predicted site-specific cartilage volume loss (β = −174.77 to −140.67; P < 0.05). BMLs present on T2-w FSE, T1-w GRE, and both MRI sequences were strongly associated with incident TKR. Conclusions: BMLs can be assessed on either T2-w FSE or T1-w GRE MRI sequence alone with no predictive advantage of performing both sequences, even though BMLs appear smaller on T1-w GRE MRI.

Placental baseline conditions modulate the hyperoxic BOLD-MRI response

ObjectivesHuman pregnancies complicated by placental dysfunction may be characterized by a high hyperoxic Blood oxygen level-dependent (BOLD) MRI response. The pathophysiology behind this phenomenon remains to be established. The aim of this study was to evaluate whether it is associated with altered placental baseline conditions, including a lower oxygenation and altered tissue morphology, as estimated by the placental transverse relaxation time (T2*). MethodWe included 49 normal pregnancies (controls) and 13 pregnancies complicated by placental dysfunction (cases), defined by a birth weight < 10th percentile in combination with placental pathological signs of vascular malperfusion. During maternal oxygen inhalation, we measured the relative ΔBOLD response ((hyperoxic BOLD – baseline BOLD)/baseline BOLD) from a dynamic single-echo gradient-recalled echo (GRE) MRI sequence and the absolute ΔT2* (hyperoxic T2*– baseline T2*) from breath-hold multi-echo GRE sequences. ResultsIn the control group, the relative ΔBOLD response increased during gestation from 5% in gestational week 20 to 20% in week 40. In the case group, the relative ΔBOLD response was significantly higher (mean Z-score 4.94; 95% CI 2.41, 7.47). The absolute ΔT2*, however, did not differ between controls and cases (p = 0.37), whereas the baseline T2* was lower among cases (mean Z-score −3.13; 95% CI -3.94, −2.32). Furthermore, we demonstrated a strong negative linear correlation between the Log10 ΔBOLD response and the baseline T2* (r = −0.88, p < 0.0001). ConclusionThe high hyperoxic ΔBOLD response demonstrated in pregnancies complicated by placental dysfunction may simply reflect altered baseline conditions, as the absolute increase in placental oxygenation (ΔT2*) does not differ between groups.

Differential involvement of nigral subregions in idiopathic parkinson's disease.

In this study, the prevalence of abnormality in putative nigrosome 1 and nigrosome 4 (N1 and N4, respectively) was investigated in early versus late-stage idiopathic Parkinson's disease (IPD) patients. A total of 128 IPD patients (early stage[n = 89]; late stage[n = 39]) and 15 healthy subjects were scanned for high-resolution (0.5 × 0.5 × 1.0mm3 ) multiecho gradient-recalled echo MRI and dopamine transporter PET imaging. The MRI data were processed for susceptibility map-weighted imaging (SMWI) to improve a contrast-to-noise ratio, and the images were resliced at 0.5 mm to define N1 and N4. When each side of N1 and N4 was assessed separately for the loss of hyperintensity by two independent reviewers, the consensus review results showed that in early-stage IPD (178 substantia nigras [SNs]), the loss of hyperintensity was observed more often in only the N1 region (65.2%) when compared to in both N1 and N4 regions (34.8%). In late-stage IPD (78 SNs), on the other hand, the loss in only the N1 region (25.6%) was less prevalent than in both N1 and N4 (74.4%) (P < 0.0001). Additionally, intact SNs (both in N1 and N4) were observed 17 SNs (9.6%) of the early-stage IPD patients, whereas it was not found in any SNs of the late-stage IPD patients (P = 0.005). Moreover, involvement of both N1 and N4 on both sides was found in 19.1% of the early-stage IPD patients, whereas its incidence was higher (61.5%) in the late-stage IPD patients (P < 0.0001), suggesting that the loss of hyperintensity in IPD progresses from N1 to N4 as the disease advances. Hum Brain Mapp 39:542-553, 2018. © 2017 Wiley Periodicals, Inc.

The Impact of Discrepancy between Measured versus Stated Weight on Hemorrhagic Transformation and Clinical Outcomes after Intravenous Alteplase Thrombolysis

Background: An accurate measurement of patient weight is important in determining the dosage for intravenous alteplase thrombolysis. In most emergency rooms, however, weight is not measured. We investigated the difference between stated and measured weight and its effect on hemorrhagic transformation and clinical outcomes. Methods: We enrolled 128 consecutive patients who had hyperacute stroke and were treated by alteplase. Alteplase dose was calculated using the weight provided by patient or guardian/caregiver, and the actual weight was measured after administration. Patients were classified into 2 groups: overused group (stated weight >measured weight) and underused group (measured weight ≥stated weight). The prevalence of hemorrhagic transformation on follow-up, determined by gradient-recalled echo MRI or non-enhanced CT, was compared between the 2 groups. The predictors for hemorrhage with progression, defined as an increase in the National Institutes of Health Stroke Scale (NIHSS) by a value of 4 or more accompanied by hemorrhage, were determined using multivariable logistic regression analysis and included the overused or underused alteplase and baseline clinical and laboratory findings. Results: Sixty-six (51.6%) of 128 patients were in the underused group and 62 patients (48.4%) in the overused group. The median difference between the stated and measured weights was 1.5 (interquartile range 0.56-3.81) kg, with the largest difference being 25.6 kg. Although there were no significant difference in baseline clinical and laboratory findings between the 2 groups, the overused group showed a significantly higher prevalence of hemorrhagic transformation (p = 0.012) and hemorrhage with progression (p = 0.025). The multivariable logistic regression analysis demonstrated that overused alteplase (OR 7.26; 95% CI 1.24-42.45; p = 0.028), baseline glucose (>144 mg/dL; OR 5.03; 95% CI 1.00-25.26; p = 0.050), and initial NIHSS (OR 1.13 per 1-point NIHSS increase; 95% CI 1.00-1.27; p = 0.047) in model 1 that use alteplase overdose as a categorical variable and overused alteplase (OR 1.67 1-mg increase; 95% CI 1.05-2.66; p = 0.027) in model 2 that use an overused alteplase dose as numerical variable were significant predictors for hemorrhage with progression. Conclusion: More alteplase usage than actual weight led to higher hemorrhagic transformation. As one of the predictors for clinical deterioration, it is important to administrate alteplase based on an accurately measured weight.

JOURNAL CLUB: Four-Dimensional Flow MRI-Based Splenic Flow Index for Predicting Cirrhosis-Associated Hypersplenism.

The objective of this study is to evaluate the ability of spleen volume, blood flow, and an index incorporating multiple measures to predict cirrhosis-associated hypersplenism. A total of 39 patients (14 women and 25 men; mean [± SD] age, 52 ± 10 years) with cirrhosis and sequelae of portal hypertension underwent 4D flow MRI and anatomic 3-T MRI performed before and after contrast administration. Unenhanced 4D flow MRI was used to assess abdominal hemodynamics, and splenic volumes were measured on T1-weighted gradient-recalled echo MRI. Relationships among demographic characteristics, blood component counts, splenic volume, arterial flow, venous flow, and the percentage of shunted portal flow were assessed in 29 consecutive patients (i.e., the derivation group), to develop a splenic flow index. This index was assessed along with splenic volume and blood flow alone in 10 additional consecutive patients (i.e., the validation group) via ROC curve analysis, to identify platelet counts of less than 50 × 103 cells/μL, leukocyte counts of less than 3.0 × 103 cells/μL, or both. In the derivation cohort (platelet count, 129 ± 76 × 103 cells/μL), splenic volume, arterial flow, venous flow, and the percentage of shunted portal flow were inversely correlated with platelet counts (ρ = -0.68, -0.68, -0.56, and -0.36, respectively; p < 0.05). Adding splenic volume to arterial flow and the product of venous flow and the percentage of shunted portal flow indexed to the body surface area yielded superior correlations with platelet counts, leukocyte counts, and the degree of severity of hypersplenism (ρ = -0.75, -0.48, and -0.75, respectively; p ≤ 0.001) and predicted severe hypersplenism (sensitivity, 100%; specificity, 100%) in the validation cohort (platelet count, 93 ± 71 × 103 cells/μL). A splenic flow index that incorporates both splenic volume and blood flow is a better indicator of hypersplenism than is splenic volume alone.

Abstract TP173: Kidney Dysfunction and Silent Brain Infarction in Generally Healthy Adults

Purpose: The association between silent brain infarction (SBI) and estimated glomerular filtration rate (eGFR)-based kidney dysfunction has not yet been definitively confirmed. This study aimed to investigate the association in generally healthy adults without a previous history of stroke or overt kidney disease. Methods: A total of 2,594 subjects who underwent brain MRI as part of health screening were included. SBIs were identified using gradient-recalled echo MRI. Kidney dysfunction was defined as eGFR &lt; 60 ml/min/1.73 m 2 . Results: The mean age was 56.8 ± 9.3 years, and 1,422 subjects (54.8%) were male. The mean eGFR level was 81.9 ± 15.4 ml/min/1.73 m 2 . The prevalence rates of kidney dysfunction and SBI were 5.1% and 7.1%, respectively. A higher proportion of subjects with SBI had kidney dysfunction than subjects without SBI (14.6% vs. 4.4%). The number of SBI lesions tended to increase with the progression of kidney dysfunction (p for trend &lt; 0.001). In multivariate logistic regression analyses, kidney dysfunction was significantly associated with the presence of SBI (adjusted odd ratio = 1.99 to 2.21 in all four models). The same significant association was consistently identified in subgroup analyses using silent lacunar infarction (adjusted odd ratio = 1.71 to 1.87 in all four models). Conclusion: Kidney dysfunction was found to be an independent risk factor for the presence and number of SBI in generally healthy adults. Physicians treating patients with a decreased creatinine-based eGFR level should try to identify and modify the coexisting risk factors ofstroke followed by SBI.

Abstract TP172: Pulmonary Function and White Matter Hyperintensity in Neurologically Healthy Adults

Introduction: Cerebral small vessel disease (SVD) is considered as precursor lesion of many clinical outcomes including stroke and dementia. It is well established that obstructive sleep apnea or chronic obstructive pulmonary disease is an independent risk factor of stroke. However, there are few studies about the association between pulmonary function and the presence of cerebral small vessel disease. Purpose: This study aims to investigate the association between pulmonary function and cerebral SVD in healthy adults. Methods: We conducted a cross-sectional study of 1,528 neurologically healthy people (mean age 56.0±9.0; 847 men), who underwent brain MRI and pulmonary function tests (forced vital capacity (FVC), forced expiratory volume in the first second (FEV 1 )). Risk factors, anthropometric parameters and clinical information were obtained. For evaluating cerebral SVD, the presence of small silent infarction (SSI) and the volume of white matter hyperintensity (WMH) were assessed through axial T2 fluid-attenuated inversion recovery (FLAIR) sequences MRI. Cerebral microbleeds (CMBs) were evaluated through T2-weighted gradient-recalled echo MRI. Results: The prevalence of SSI and CMBs were 9.6% (147 subjects) and 4.1% (63 subjects), respectively. The mean volume of WMH was 2.8±6.2mm 3 . In multiple regression analysis that controlled for age, sex, and smoking status, FVC had a significant negative correlation with WMH volume (R 2 =0.005, β=-0.109, p=0.002), and FEV 1 /FVC ratio had a significant correlation with WMH volume (R 2 =0.006, β=0.083, p=&lt;0.001). In multivariable logistic analysis, after adjusting age, gender, hypertension, and glucose, FVC was negatively associated with the presence of SSI (adjusted OR 0.63, 95% CI 0.44-0.91), and FEV 1 /FVC ratio was positively associated with the presence of SSI (adjusted OR 1.05, 95% CI 1.02-1.08). The presence of CMBs was not associated with any factor of pulmonary function tests. Conclusions: The results from our study suggest that lower pulmonary function, especially FVC, was found to be an independent risk factor of cerebral SVD in neurologically healthy adults.