Gradient-recalled Echo Magnetic Resonance Imaging Research Articles

Hemosiderin deposition evaluation in hemophilic ankle joints: association between US finding and gradient-recalled echo MR imaging sequence

BackgroundRepeated bleeding in hemophilic arthropathy (HA) may result in severe degenerative changes and joint destruction. The gradient-recalled echo (GRE) sequence MR is proved to be the best method to detect hemosiderin deposition. However, MR is not widely available in developing countries, including Indonesia. Some studies have proposed ultrasonography (US) as an alternative tool in evaluating hemophilic joint. However, there is still some disagreement on the ability of US to detect hemosiderin deposition.ObjectiveTo evaluate the association between US and GRE-sequence MR imaging in detecting hemosiderin deposition in hemophilic ankle joint.Material and methodsA total of 102 sites from 17 ankle joints of 11 boys with severe hemophilia A underwent US examination using a high-frequency linear array transducer. GRE-sequence MR examination was performed in sagittal view consistent with the sites scanned by US. Both examinations were performed on the same day, but MR interpretation was performed blindly at different times. The association between US and GRE-sequences in detecting hemosiderin deposition was analyzed using McNemar’s test.ResultsStatistical analysis showed a significant association (p value < 0.001) between US and GRE MR in detecting hemosiderin deposition, but the association is weak (R = 0.26). Sensitivity and specificity of US for detecting hemosiderin deposition were 46.84% (95%CI: 35.51–58.40) and 95.65% (95%CI: 78.05–99.89), respectively, with positive predictive value 97.37% (95%CI: 84.29–99.61), negative predictive value 34.38% (95%CI: 29.50–39.60) and accuracy 57.84% (95%CI: 47.66–67.56).ConclusionThere was a weak association between US and GRE-sequences in detecting hemosiderin deposition of hemophilic ankle joint. ​​

Cerebral Microbleeds: Relationship to Antithrombotic Medications.

Cerebral microbleeds (CMBs) are represented by small areas of hemosiderin deposition, detected on brain magnetic resonance imaging (MRI), and found in ≈23% of the cognitively normal population over age of 60 years. CMBs predict risk of hemorrhagic and ischemic stroke. They correlate with increased cardiovascular mortality. In this article, we sought to determine in a population-based study whether antithrombotic medications correlate with CMBs and, if present, whether the association was direct or mediated by another variable. The study consisted of 1253 participants from the population-based Mayo Clinic Study of Aging who underwent T2* gradient-recalled echo magnetic resonance imaging. We tested the relationship between antithrombotic medications and CMB presence and location, using multivariable logistic-regression models. Ordinal logistic models tested the relationship between antithrombotics and CMB frequency. Using structural equation models, we assessed the effect of antithrombotic medications on presence/absence of CMBs and count of CMBs in the CMB-positive group, after considering the effects of age, sex, vascular risk factors, amyloid load by positron emission tomography, and apoE. Two hundred ninety-five participants (26.3%) had CMBs. Among 678 participants taking only antiplatelet medications, 185 (27.3%) had CMBs. Among 95 participants taking only an anticoagulant, 43 (45.3%) had CMBs. Among 44 participants taking an anticoagulant and antiplatelet therapy, 21 (48.8%) had CMBs. Anticoagulants correlated with the presence and frequency of CMBs, whereas antiplatelet agents were not. Structural equation models showed that predictors for presence/absence of CMBs included older age at magnetic resonance imaging, male sex, and anticoagulant use. Predictors of CMB count in the CMB-positive group were male sex and amyloid load. Anticoagulant use correlated with presence of CMBs in the general population. Amyloid positron emission tomography correlated with the count of CMBs in the CMB-positive group.

Oral anticoagulant use and the development of new cerebral microbleeds in cardioembolic stroke patients with atrial fibrillation.

ObjectiveCerebral microbleeds (CMBs) are a magnetic resonance imaging (MRI) marker for cerebral small vessel disease. Existing CMBs and those that newly develop are associated with the risks of stroke incidence and recurrence. The purpose of the present study was to investigate the association of oral anticoagulant (OAC) use and the development of new CMBs in cardioembolic stroke patients with atrial fibrillation.Subjects and methodsWe prospectively followed cardioembolic stroke patients with atrial fibrillation who had been hospitalized in the stroke center of our hospital, had been prescribed anticoagulants at discharge, and underwent repeated brain MRI with an interval of at least one year from the baseline MRI. Assessing the presence, number and location of CMBs using T2*-weighted gradient-recalled echo MRI, we used logistic regression models to investigate the associations between OAC use and the incidence of new CMBs. We also examined associations of subsequent stroke with OACs and CMBs during the follow-up.ResultsA total of 81 patients, consisting of 45 patients receiving direct oral anticoagulants (DOACs) and 36 patients receiving warfarin (WF), were analyzed in the present study. Baseline CMBs were observed in 19/81 patients (23.5%) and new CMBs in 18/81 patients (22.2%) on follow-up MRI (median interval, 34 months). Of the 31 new CMBs, 25 (80.6%) developed in the lobar location and 6 (19.4%) in the deep or infratentorial location. New CMBs occurred in 4 patients (10.0%) taking DOACs alone, in 10 patients (35.7%) taking WF alone, in 3 patients (37.5%) taking WF plus antiplatelet agents and in 1 patient (20.0%) taking DOAC plus antiplatelet agent. Regarding location, the new CMBs were the lobar type in 7 of the 10 patients taking WF alone, as well as in 3 of the 4 patients taking DOACs alone. In multivariate analysis, the presence of CMBs at baseline and WF use (vs. DOAC use) were associated with new CMBs (CMB presence at baseline: OR 4.16, 95% CI 1.19–14.44; WF use: OR 3.38, 95% CI 1.02–11.42). The presence of ≥ 2 CMBs at baseline was related to a higher risk of subsequent stroke (OR 7.25, 95% CI 1.01–52.35, P = 0.048).ConclusionOur findings suggest that DOAC compared with WF use at discharge is associated with a lower incidence of new CMBs in cardioembolic stroke patients with atrial fibrillation. Further prospective studies in the clinical setting are needed to confirm our exploratory data.

Prevalence and Heterogeneity of Cerebrovascular Disease Imaging Lesions

ObjectiveTo report population age-specific prevalence of core cerebrovascular disease lesions (infarctions, cerebral microbleeds, and white-matter hyperintensities detected with magnetic resonance imaging); estimate cut points for white-matter hyperintensity positivity; investigate sex differences in prevalence; and estimate prevalence of any core cerebrovascular disease features. Patients and MethodsParticipants in the population-based Mayo Clinic Study of Aging aged 50 to 89 years underwent fluid-attenuated inversion recovery and T2* gradient-recalled echo magnetic resonance imaging to assess cerebrovascular disease between October 10, 2011, and September 29, 2017. We characterized each participant as having infarct, normal versus abnormal white-matter hyperintensity, cerebral microbleed, or a combination of lesions. Prevalence of cerebrovascular disease biomarkers was derived through adjustment for nonparticipation and standardization to the population of Olmsted County, Minnesota. ResultsAmong 1462 participants without dementia (median [range] age, 68 [50 to 89] y; men, 52.7%), core cerebrovascular disease features increased with age. Prevalence (95% CI) of cerebral microbleeds was 13.6% (11.6%-15.6%); infarcts, 11.7% (9.7%-13.8%); and abnormal white-matter hyperintensity, 10.7% (8.7%-12.6%). Infarcts and cerebral microbleeds were more common among men. In contrast, abnormal white-matter hyperintensity was more common among women ages 60 to 79 y and men, ages 80 y and older. Prevalence of any core cerebrovascular disease feature determined by presence of at least one cerebrovascular disease feature increased from 9.5% (ages 50 to 59 y) to 73.8% (ages 80 to 89 y). ConclusionWhereas this study focused on participants without dementia, the high prevalence of cerebrovascular disease imaging lesions in elderly persons makes assignment of clinical relevance to cognition and other downstream manifestations more probabilistic than deterministic.

Influence of 7T GRE-MRI Signal Compartment Model Choice on Tissue Parameters.

Quantitative assessment of tissue microstructure is important in studying human brain diseases and disorders. Ultra-high field magnetic resonance imaging (MRI) data obtained using a multi-echo gradient echo sequence have been shown to contain information on myelin, axonal, and extracellular compartments in tissue. Quantitative assessment of water fraction, relaxation time (T2*), and frequency shift using multi-compartment models has been shown to be useful in studying white matter properties via specific tissue parameters. It remains unclear how tissue parameters vary with model selection based on 7T multiple echo time gradient-recalled echo (GRE) MRI data. We applied existing signal compartment models to the corpus callosum and investigated whether a three-compartment model can be reduced to two compartments and still resolve white matter parameters [i.e., myelin water fraction (MWF) and g-ratio]. We show that MWF should be computed using a three-compartment model in the corpus callosum, and the g-ratios obtained using three compartment models are consistent with previous reports. We provide results for other parameters, such as signal compartment frequency shifts.

Development and characterization of a tissue mimicking psyllium husk gelatin phantom for ultrasound and magnetic resonance imaging

Purpose To develop and characterize a tissue-mimicking phantom that enables the direct comparison of magnetic resonance (MR) and ultrasound (US) imaging techniques useful for monitoring high-intensity focused ultrasound (HIFU) treatments. With no additions, gelatin phantoms produce little if any scattering required for US imaging. This study characterizes the MR and US image characteristics as a function of psyllium husk concentration, which was added to increase US scattering. Methods Gelatin phantoms were constructed with varying concentrations of psyllium husk. The effects of psyllium husk concentration on US B-mode and MR imaging were evaluated at nine different concentrations. T1, T2, and T2* MR maps were acquired. Acoustic properties (attenuation and speed of sound) were measured at frequencies of 0.6, 1.0, 1.8, and 3.0 MHz using a through-transmission technique. Phantom elastic properties were evaluated for both time and temperature dependence. Results Ultrasound image echogenicity increased with increasing psyllium husk concentration while quality of gradient-recalled echo MR images decreased with increasing concentration. For all phantoms, the measured speed of sound ranged between 1567–1569 m/s and the attenuation ranged between 0.42–0.44 dB/(cm·MHz). Measured T1 ranged from 974–1051 ms. The T2 and T2* values ranged from 97–108 ms and 48–88 ms, respectively, with both showing a decreasing trend with increased psyllium husk concentration. Phantom stiffness, measured using US shear-wave speed measurements, increased with age and decreased with increasing temperature. Conclusions The presented dual-use tissue-mimicking phantom is easy to manufacture and can be used to compare and evaluate US-guided and MR-guided HIFU imaging protocols.

Traumatic Microbleeds in the Hippocampus and Corpus Callosum Predict Duration of Posttraumatic Amnesia.

Radiologic predictors of posttraumatic amnesia (PTA) duration are lacking. We hypothesized that the number and distribution of traumatic microbleeds (TMBs) detected by gradient recalled echo (GRE) magnetic resonance imaging (MRI) predicts PTA duration. Academic, tertiary medical center. Adults with traumatic brain injury (TBI). We identified 65 TBI patients with acute GRE MRI. PTA duration was determined with the Galveston Orientation and Amnesia Test, Orientation Log, or chart review. TMBs were identified within memory regions (hippocampus, corpus callosum, fornix, thalamus, and temporal lobe) and control regions (internal capsule and global). Regression tree analysis was performed to identify radiologic predictors of PTA duration, controlling for clinical PTA predictors. TMB distribution, PTA duration. Sixteen patients (25%) had complicated mild, 4 (6%) had moderate, and 45 (69%) had severe TBI. Median PTA duration was 43 days (range, 0-240 days). In univariate analysis, PTA duration correlated with TMBs in the corpus callosum (R = 0.29, P = .02) and admission Glasgow Coma Scale (GCS) score (R = -0.34, P = .01). In multivariate regression analysis, admission GCS score was the only significant contributor to PTA duration. However, in regression tree analysis, hippocampal TMBs, callosal TMBs, age, and admission GCS score explained 26% of PTA duration variance and distinguished a subgroup with prolonged PTA. Hippocampal and callosal TMBs are potential radiologic predictors of PTA duration.

Visualization of the normal appendix in children: feasibility of a single contrast-enhanced radial gradient recalled echo MRI sequence.

Magnetic resonance imaging (MRI) assessment for appendicitis is limited by exam time and patient cooperation. The radially sampled 3-dimensional (3-D) T1-weighted, gradient recalled echo sequence (radial GRE) is a free-breathing, motion robust sequence that may be useful in evaluating appendicitis in children. To compare the rate of detection of the normal appendix with contrast-enhanced radial GRE versus contrast-enhanced 3-D GRE and a multi-sequence study including contrast-enhanced radial GRE. This was a retrospective study of patients ages 7-18years undergoing abdominal-pelvic contrast-enhanced MRI between Jan. 1, 2012, and April 1, 2016. Visualization of the appendix was assessed by consensus between two pediatric radiologists. The rate of detection of the appendix for each sequence and combination of sequences was compared using a McNemar test. The rate of detection of the normal appendix on contrast-enhanced radial GRE was significantly higher than on contrast-enhanced 3-D GRE (76% vs. 57.3%, P=0.003). The rate of detection of the normal appendix with multi-sequence MRI including contrast-enhanced radial GRE was significantly higher than on contrast-enhanced 3-D GRE (81.3% vs. 57%, P<0.001). There was no significant difference between the rate of detection of the normal appendix on contrast-enhanced radial GRE alone and multi-sequence MRI including contrast-enhanced radial GRE (76% vs. 81.3%, P=0.267). Contrast-enhanced radial GRE allows superior detection of the normal appendix compared to contrast-enhanced 3-D GRE. The rate of detection of the normal appendix on contrast-enhanced radial GRE alone is nearly as good as when the contrast-enhanced radial GRE is interpreted with additional sequences.

Signal compartments in ultra-high field multi-echo gradient echo MRI reflect underlying tissue microstructure in the brain

Gradient recalled echo magnetic resonance imaging (GRE-MRI) at ultra-high field holds great promise for new contrast mechanisms and delineation of putative tissue compartments that contribute to the multi-echo GRE-MRI signal may aid structural characterization. Several studies have adopted the three water-pool compartment model to study white matter brain regions, associating individual compartments with myelin, axonal and extracellular water. However, the number and identifiability of GRE-MRI signal compartments has not been fully explored. We undertook this task for human brain imaging data. Multiple echo time GRE-MRI data were acquired in five healthy participants, specific anatomical structures were segmented in each dataset (substantia nigra, caudate, insula, putamen, thalamus, fornix, internal capsule, corpus callosum and cerebrospinal fluid), and the signal fitted with models comprising one to six signal compartments using a complex-valued plane wave formulation. Information criteria and cluster analysis methods were used to ascertain the number of distinct compartments within the signal from each structure and to determine their respective frequency shifts. We identified five principal signal compartments with different relative contributions to each structure's signal. Voxel-based maps of the volume fraction of each of these compartments were generated and demonstrated spatial correlation with brain anatomy.

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.

Two-Dimensional Spoiled Gradient-Recalled Echo Magnetic Resonance Imaging of the Liver Using Respiratory Navigator-Gating Techniques.

We assessed the feasibility of T1-weighted 2-dimensional spoiled gradient-recalled (2D SPGR) acquisition in steady-state imaging of the liver with various respiratory navigator gating techniques. A total of 12 healthy volunteers underwent in-phase and out-of-phase 2D SPGR imaging of the liver during breath-holding and free-breathing. Four techniques for respiratory navigation, 2 conventional navigator techniques and 2 self-navigator techniques, were used for free-breathing imaging. Good navigator waveforms were obtained in conventional navigation, whereas fluctuations were evident in self navigation. All of the 4 navigator-based methods provided better images in terms of background signals and visual image quality compared with images obtained with no respiratory control. However, differences remained in comparison with breath-holding. Superiority of self-navigation to conventional navigation was not shown. Navigator-gating techniques improved 2D SPGR images of the liver acquired during free-breathing, suggesting feasibility and beneficial effects, although navigator-based images were still inferior to breath-hold images.

Volumetric abnormalities of thalamic subnuclei in medication-overuse headache

BackgroundThe thalamus exerts a pivotal role in pain processing and cortical excitability control and a previous voxel-based morphometry study confirmed increased volume in bilateral thalamus in medication-overuse headache (MOH). The aim of this study is to investigate altered thalamic subnuclei volume in MOH compared with normal controls, and to evaluate the relationship of each thalamic subnuclei volume with the clinical variables.MethodsHigh resolution three-dimensional T1-weighted fast spoiled gradient recalled echo MR images were obtained from 27 patients with MOH and 27 normal controls (NC). Thalamic subnuclei templates were created based on Talairach template with MNI space transformation, and the individual thalamic subnuclei templates were generated by applying the deformation field from structural image segment to the thalamic subnuclei templates, and then individual thalamci subnuclei volume were calculated.ResultsThe whole thalamus and each thalamic subnuclei presented increased volume compared with NC (P < 0.05). The correlation analysis demonstrated that the whole thalamus volume and each thalamic subnuclei volume showed a negative relationship with HAMD scores(P < 0.05), and no any correlation with HAMA, VAS score and disease duration (P > 0.05).ConclusionIncreased gray matter volume in the whole thalamus and all the thalamus subnuclei may reflect central sensitization and higher-order of pain alteration in MOH. These structural changes in the thalamus may also be influenced by mood disturbances related to the MOH.

Volume gain of periaqueductal gray in medication-overuse headache

BackgroundPeriaqueductal gray (PAG) is a substantial descending pain modulatory center, and previous voxel-based morphometry study confirmed the clusters with increased volume in PAG region in medication-overuse headache (MOH). The aim of this study is to investigate altered PAG volume in MOH using an automated PAG segment method to measure the true PAG volume.MethodsHigh resolution three-dimensional T1-weighted fast spoiled gradient recalled echo MR images were obtained from 22 patients with MOH and 22 normal controls (NC). PAG template was created based on ICBM 152 gray template, and the individual PAG was generated by applying the deformation field from structural image segment to the PAG template, and individual PAG volume was calculated.ResultsThere was a significant increased volume of PAG in MOH (0.366 ± 0.005 ml) than that in NC (0.341 ± 0.005 ml)(P < 0.05). There was no significant correlation between the PAG volume and the clinical variables in MOH patients (P > 0.05). The area of receiver operating characteristic (ROC) curve was 0.845, and the cut-off of PAG volume was 0.341 ml with sensitivity 95.5% and specificity 63.6%.ConclusionThe present study demonstrated that the PAG volume gain was confirmed in MOH patients, and the automated individual PAG volume measure may be considered as a simple and effective imaging biomarker in MOH diagnosis.

Abnormal Alterations of Cortical Thickness in 16 Patients with Type 2 Diabetes Mellitus: A Pilot MRI Study.

Objective The aim of this study is to investigate the cerebral cortical thickness changes in type 2 diabetes mellitus (T2DM) using a whole brain cortical thickness mapping system based on brain magnetic resonance imaging (MRI).Methods High resolution three-dimensional T1-weighted fast spoiled gradient recalled echo MR images were obtained from 16 patients with T2DM, as well as from 16 normal controls. The whole brain cortical thickness maps were generated, and the cortical thickness of each brain region was calculated according to gyral based regions of interest (ROI) using an automated labeling system by the Freesurfer software. We compared mean cortical thickness at each brain region by the analysis of covariance with age and sex as covariates. The regional difference of the cortical thickness over the whole brain was compared by the analysis of surface-based cortical thickness.Results Mean cortical thicknesses analysis showed bilateral cerebrum in the patients with T2DM (left: 2.52±0.07 mm; right: 2.51±0.08 mm) were significant thinner than those in the normal controls (left: 2.56±0.09 mm; right: 2.56±0.09 mm) (both P<0.05). Regional cortical thinning in T2DM was demonstrated in the paracentral lobule, postcentral gyrus, lateral occipital gyrus, lingual gyrus, precuneus, superior temporal gyrus, middle temporal gyrus, inferior temporal gyrus and posterior cingulate gyrus, compared to the normal controls. The cortical thickness of left middle cingulate and right inferior temporal gyrus were negatively correlated with the disease course.Conclusion A widespread cortical thinning was revealed in patients with T2DM by the analysis of brain cortical thickness on MR. Our finding supports the idea that T2DM could lead to subtle diabetic brain structural changes.

All-Inside, All-Epiphyseal Anterior Cruciate Ligament Reconstruction in Skeletally Immature Athletes: Return to Sport, Incidence of Second Surgery, and 2-Year Clinical Outcomes

Background: Anterior cruciate ligament (ACL) injuries in skeletally immature athletes are increasing. Purpose: To evaluate the 2-year clinical outcomes of all-inside, all-epiphyseal ACL reconstruction in skeletally immature athletes with 3 to 6 years of remaining growth, with a focus on return to sport and the incidence of second surgery. Study Design: Case series; Level of evidence, 4. Methods: Twenty-three skeletally immature athletes were prospectively evaluated after all-epiphyseal ACL reconstruction utilizing a hamstring autograft. The athletes’ age, sex, sport, mechanism of injury, radiographs, and magnetic resonance imaging (MRI) findings were noted. The evaluation included a physical examination, KT-1000 arthrometer measurements, isokinetic testing, and validated outcome scores. Standing radiographs and spoiled gradient recalled echo MRI scans were obtained at 6, 12, and 24 months postoperatively. A quality of movement assessment and return-to-sport performance analysis were also performed. Results: Of the 23 athletes, 6 were female (mean age, 11.3 years), and 17 were male (mean age, 12.6 years). At a minimum follow-up of 2 years (range, 24-45 months), the mean International Knee Documentation Committee score was 94.6 ± 4.9, the mean Lysholm score was 97.9 ± 4.0, the mean Marx activity rating scale score was 13.4 ± 3.6, and the mean Hospital for Special Surgery Pediatric Functional Activity Brief Scale score was 23.9 ± 7.0. Lachman and pivot-shift test results were negative in all patients. The mean side-to-side difference on the KT-1000 arthrometer was 0.9 ± 0.5 mm and less tight on the operated side. No significant growth disturbances were noted; however, 6 athletes had a leg-length discrepancy of more than 5 mm (range, 6-18 mm). Two patients had overgrowth in the femur of more than 15 mm (16 mm and 18 mm). Two athletes (8.7%) required second surgery. The mean time to return to unrestricted activity was 13.5 months (range, 8-22 months). Conclusion: The all-inside, all-epiphyseal ACL reconstruction technique using a hamstring autograft demonstrates excellent subjective and objective clinical outcomes in skeletally immature athletes without physeal arrest.

Effect and Safety of Rosuvastatin in Acute Ischemic Stroke.

Background and PurposeThe benefit of statins in acute stroke remains uncertain. Statins may prevent stroke recurrence during the acute stage of stroke via pleiotropic effects. However, statins may increase the risk of intracerebral hemorrhage. We investigated the effect and safety of rosuvastatin in acute stroke patients.MethodsThis randomized, double-blind, multi-center trial compared rosuvastatin 20 mg and placebo in statin-naïve stroke patients who underwent diffusion-weighted imaging (DWI) within 48 hours after symptom onset. The primary outcome was occurrence of new ischemic lesions on DWI at 5 or 14 days.ResultsThis trial was stopped early after randomization of 316 patients due to slow enrollment. Among 289 patients with at least one follow-up imaging, the frequency of new ischemic lesions on DWI was not different between groups (rosuvastatin: 27/137, 19.7% vs. placebo: 36/152, 23.6%) (relative risk 0.83, 95% confidence interval 0.53–1.30). Infarct volume growth at 5 days (log-transformed volume change, rosuvastatin: 0.2±1.0 mm3 vs. placebo: 0.3±1.3 mm3; P=0.784) was not different, either. However, hemorrhagic infarction or parenchymal/subarachnoid hemorrhage on gradient-recalled echo magnetic resonance imaging occurred less frequently in the rosuvastatin group (6/137, 4.4%) than the placebo group (22/152, 14.5%, P=0.007). Among 314 patients with at least one dose of study medication, progression or clinical recurrence of stroke tended to occur less frequently in the rosuvastatin group (1/155, 0.6% vs. 7/159, 4.4%, P=0.067). Adverse events did not differ between groups.ConclusionsThe efficacy of rosuvastatin in reducing recurrence in acute stroke was inconclusive. However, statin use was safe and reduced hemorrhagic transformation.

Thrombus Characteristics Are Related to Collaterals and Angioarchitecture in Acute Stroke

We have theorized that clots with stasis are longer. We therefore explored the relationship between thrombus imaging characteristics on noncontrast computed tomography (NCCT) and magnetic resonance imaging (MRI) with clot length and pial collaterals on baseline computed tomography angiography (CTA). Prospective study of acute ischemic stroke patients (2005-2009) from Keimyung University. Patients with known stroke symptom onset time, baseline CTA, MRI, and with M1-Middle Cerebral Artery (MCA)±intracranial internal carotid artery (ICA) occlusions were included. Clot length and pial collaterals were measured on baseline CTA. A total of 104 patients (mean age 65.1±12.28 years, 56.7% male, median baseline National Institutes of Health Stroke Scale 13) with intracranial ICA + MCA (n=50) or isolated M1-MCA (n=54) occlusions were included. Hyperdense sign on NCCT had a median clot length of 42.3 mm versus 29.5 mm when hyperdense negative (p=0.02). Clots showing blooming artifact on gradient recall echo MRI had a median length of 39.1 mm versus 24.5 mm without blooming (p=0.005). Patients with poor baseline collaterals on CTA had longer clots than those with intermediate/good collaterals (median clot length 49.4 mm vs 34.9 mm vs 20.5 mm respectively, p<0.001). In censored logistic regression modeling, clot length was an independent predictor of hyperdense sign (p=0.05) and of the presence of blooming artifact (p=0.006). Clot length and baseline collateral status are independent predictors of clot hyperdensity on NCCT and blooming artifact on gradient recall echo. Longer clots are more likely to be hyperdense and to bloom more, probably because portions of these clots are freshly formed locally due to of stasis of blood around the original clot. This stasis could be because of poor collaterals and inefficient angio-architecture within the cerebral arterial tree.

Postoperative lumbar epidural abscess: conventional and advanced magnetic resonance imaging findings

A 54-year-old female patient was admitted to our departmentwithnumbnessinbothlowerextremitiesduringthepast 2 weeks. She had a history of discectomy surgery. Spinal magneticresonance(MR)imagingwasperformed.Magnetic resonance imaging revealed an extradural mass. The lesion was iso-hyperintense on T2-weighted images comparing muscle intensity (Fig. 1, Left and Right). Abscess or hematoma was considered for different diagnosis of mass. Gradient-recalled echo, diffusion- and contrast-enhanced MR imaging were performed. The mass was hyperintense on hemo sequence (Fig. 2). Thus, hematoma was excluded. On the diffusion-weighted imaging, the lesion was homogeneousincreasedsignalintensity.Theapparentdiffusioncoefficient map showed significant diffusion restriction (Fig. 3, Left and Right). The mass was also peripherally contrast enhanced (Fig. 4, Top, Bottom, and Right). With the MR imaging findings, the lesion was considered as an epidural abscess. Drainage treatment for abscess was planned. An urgent reoperation was performed. There was yellowish liquid pus in the extradural area. She was treated with evacuation of the epidural abscess. No additional pathologic findings were observed in the extradural area. Culture showed methicillin-susceptible Staphylococcus aureus. Appropriate antibiotics were administered. With an intensive treatment, the patient showed good neurologic improvement and was discharged after 8 weeks of IV antibiotic therapy.

Accuracy of Magnetic Resonance Imaging in Diagnosis of Liver Iron Overload: A Systematic Review and Meta-analysis

Guidelines advocate use of magnetic resonance imaging (MRI) to estimate concentrations of iron in liver, to identify patients with iron overload, and to guide titration of chelation therapy. However, this recommendation was not based on a systematic synthesis and analysis of the evidence for MRI's diagnostic accuracy. We conducted a systematic review and meta-analysis to investigate the diagnostic accuracy of MRI in identifying liver iron overload in patients with hereditary hemochromatosis, hemoglobinopathy, or myelodysplastic syndrome; liver biopsy analysis was used as the reference standard. We searched MEDLINE and EMBASE databases, the Cochrane Library, and gray literature, and computed summary receiver operating curves by fitting hierarchical models. We assessed methodologic quality using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. Our final analysis included 20 studies (819 patients, total). Sensitivity and specificity values varied greatly, ranging from 0.00 to 1.00 and from 0.50 to 1.00, respectively. Because of substantial heterogeneity and variable positivity thresholds, we calculated only summary receiver operating curves (and summary estimate points for studies that used the same MRI sequences). T2 spin echo and T2* gradient-recalled echo MRI sequences accurately identified patients without liver iron overload (liver iron concentration > 7 mg Fe/g dry liver weight) (negative likelihood ratios, 0.10 and 0.05 respectively). However, these MRI sequences are less accurate in establishing a definite diagnosis of liver iron overload (positive likelihood ratio, 8.85 and 4.86, respectively). Based on a meta-analysis, measurements of liver iron concentration by MRI may be accurate enough to rule out iron overload, but not to definitely identify patients with this condition. Most studies did not use explicit and prespecified MRI thresholds for iron overload, therefore some patients may have been diagnosed inaccurately with this condition. More studies are needed of standardized MRI protocols and to determine the effects of MRI surveillance on the development of chronic liver disease and patient survival.

Cartilage signal intensity on T1-weighted MRI: association with risk factors and measures of knee osteoarthritis

This study aims to assess mean signal intensity of cartilage on T1-weighted magnetic resonance imaging (MRI) images, and then examine whether mean signal intensity is associated with risk factors and measures of osteoarthritis in younger and older adults. A total of 50 younger adult subjects (mean age 41, range 29-57; 64% female; baseline only) and 168 older adult subjects (mean age 63, range 52-78; 46% female; baseline and 2.9 year followup) were randomly selected from the community. T1-weighted fat-supressed gradient recall echo MRI scans of right knees were performed. Image segmentation was performed semi-automatically, and measures of mean signal intensity and cartilage thickness for regions of cartilage were obtained. Urinary levels of C-terminal crosslinking telopeptide of type II collagen (U-CTX-II) were measured in younger adults. Cartilage defects were scored using a 5-point scale in both groups. In multivariable analyses, higher cartilage defects and BMI were significantly associated with lower same-region mean signal intensity in younger and older adults. CTX-II was negatively and significantly associated with mean signal intensity of cartilage in the lateral femoral and patellar sites. Joint space narrowing and osteophytes analysed in older adults were significantly associated with reduced mean signal intensity at various sites. Over 2.9 years, lower mean signal intensity at femoral and patellar sites and in whole knee was associated with decreases in cartilage thickness. Reduced mean signal intensity of cartilage on T1-weighted gradient recall echo MRI is associated with osteoarthritis risk factors and predicts cartilage loss suggesting low cartilage signal intensity may reflect early osteoarthritic changes.