Editor’s Choices

Clinical Feasibility of Synthetic MRI in Multiple Sclerosis: A Diagnostic and Volumetric Validation Study

Editor’s Choice

SyMRI is a quantitative synthetic MR imaging method where a single saturation recovery TSE sequence is used to estimate the proton density, longitudinal relaxation rate, and transverse relaxation rate and allows for a free range of synthetic weightings. Twenty patients with MS and 20 healthy controls were enrolled and synthetic MR imaging was implemented on a Siemens 3T scanner. Diagnostic accuracy, lesion detection, and artifacts were assessed by blinded neuroradiologic evaluation, and CNR by manual tracing. Synthetic PD-, T1-, and T2-weighted images were of sufficient or good quality and were acquired in 7% less time than with conventional MRI. Synthetic FLAIR images suffered from artifacts. Also, synthetic MRI provided segmentations with the shortest processing time (16 seconds) and the lowest repeatability error for brain volume. Synthetic MRI can be an alternative to conventional MRI for generating diagnostic PD-, T1-, and T2-weighted images in patients with MS with fast and robust volumetric measurements.

Abstract

Conventional (top row) and synthetic (middle row) axial noncontrast MR imaging in a 49-year-old male patient with MS, from left to right: T1-, PD-, and T2-weighted, and FLAIR images. The bottom row shows brain tissue segmentations of the WM (cyan), GM (green), CSF (magenta), and other remaining brain tissues (yellow) from SyMRI.
Conventional (top row) and synthetic (middle row) axial noncontrast MR imaging in a 49-year-old male patient with MS, from left to right: T1-, PD-, and T2-weighted, and FLAIR images. The bottom row shows brain tissue segmentations of the WM (cyan), GM (green), CSF (magenta), and other remaining brain tissues (yellow) from SyMRI.

BACKGROUND AND PURPOSE

Quantitative MR imaging techniques are gaining interest as methods of reducing acquisition times while additionally providing robust measurements. This study aimed to implement a synthetic MR imaging method on a new scanner type and to compare its diagnostic accuracy and volumetry with conventional MR imaging in patients with MS and controls.

MATERIALS AND METHODS

Twenty patients with MS and 20 healthy controls were enrolled after ethics approval and written informed consent. Synthetic MR imaging was implemented on a Siemens 3T scanner. Comparable conventional and synthetic proton-density–, T1-, and T2-weighted, and

Brain Structural and Vascular Anatomy Is Altered in Offspring of Pre-Eclamptic Pregnancies: A Pilot Study

Editor’s Choice

The authors assessed the brain structural and vascular anatomy in 7- to 10-year-old offspring of pre-eclamptic pregnancies compared with matched controls (n=10 per group). TOF-MRA and a high-resolution anatomic T1-weighted MPRAGE sequence were acquired for each participant. Offspring of pre-eclamptic pregnancies exhibited enlarged brain regional volumes of the cerebellum, temporal lobe, brain stem, and right and left amygdalae. These offspring displayed reduced cerebral vessel radii in the occipital and parietal lobes. The authors conclude that these structural and vascular anomalies may underlie the cognitive deficits reported in the pre-eclamptic offspring population.

Abstract

Visual 3D representation of the vessel radii calculated for a segmented TOF-MRA dataset of a single female, 8-year-old PE-F1 participant who was born at 34 weeks of gestation.
Visual 3D representation of the vessel radii calculated for a segmented TOF-MRA dataset of a single female, 8-year-old PE-F1 participant who was born at 34 weeks of gestation.

BACKGROUND AND PURPOSE

Pre-eclampsia is a serious clinical gestational disorder occurring in 3%–5% of all human pregnancies and characterized by endothelial dysfunction and vascular complications. Offspring born of pre-eclamptic pregnancies are reported to exhibit deficits in cognitive function, higher incidence of depression, and increased susceptibility to stroke. However, no brain imaging reports exist on these offspring. We aimed to assess brain structural and vascular anatomy in 7- to 10-year-old offspring of pre-eclamptic pregnancies compared with matched controls.

MATERIALS AND METHODS

Offspring of pre-eclamptic pregnancies and matched controls (n = 10 per group) were recruited from an established longitudinal cohort examining the effects of pre-eclampsia. Children underwent MR imaging to identify brain structural and vascular anatomic differences. Maternal plasma samples collected at birth were assayed for angiogenic factors by enzyme-linked immunosorbent assay.

RESULTS

Offspring of pre-eclamptic pregnancies exhibited enlarged brain regional volumes of the cerebellum, temporal lobe, brain stem, and right and left amygdalae. These offspring displayed reduced cerebral vessel radii in the occipital and parietal lobes. Enzyme-linked immunosorbent assay analysis revealed underexpression of the placental growth factor

Mitotic Activity in Glioblastoma Correlates with Estimated Extravascular Extracellular Space Derived from Dynamic Contrast-Enhanced MR Imaging

Editor’s Choice

Twenty-eight patients with newly presenting glioblastoma multiforme underwent preoperative conventional imaging and T1 dynamic contrast-enhanced MRI. Parametric maps of the initial area under the contrast agent concentration curve, contrast transfer coefficient, estimate of volume of the extravascular extracellular space, and estimate of blood plasma volume were generated, and the enhancing fraction was calculated. High values of the estimate of volume of the extravascular extracellular space were associated with a fibrillary histologic pattern and increased mitotic activity. This finding is counterintuitive to the standard concept that more proliferative tumors would be more densely packed with cells and have less extracellular space. As the authors point out, this surprising finding requires more investigation to understand whether this relationship will hold, and what the underlying mechanism might be.

Abstract

Scatterplot of mitotic activity versus ve (P = .012, ρ = 0.470), marker shapes depict separate scores of cell density measures.
Scatterplot of mitotic activity versus ve (P = .012, ρ = 0.470), marker shapes depict separate scores of cell density measures.

BACKGROUND AND PURPOSE

A number of parameters derived from dynamic contrast-enhanced MR imaging and separate histologic features have been identified as potential prognosticators in high-grade glioma. This study evaluated the relationships between dynamic contrast-enhanced MRI–derived parameters and histologic features in glioblastoma multiforme.

MATERIALS AND METHODS

Twenty-eight patients with newly presenting glioblastoma multiforme underwent preoperative imaging (conventional imaging and T1 dynamic contrast-enhanced MRI). Parametric maps of the initial area under the contrast agent concentration curve, contrast transfer coefficient, estimate of volume of the extravascular extracellular space, and estimate of blood plasma volume were generated, and the enhancing fraction was calculated. Surgical specimens were used to assess subtype and were graded (World Health Organization classification system) and were assessed for necrosis, cell density, cellular atypia, mitotic activity, and overall vascularity scores. Quantitative assessment of endothelial surface area, vascular surface area, and a vascular profile count were made by using CD34 immunostaining. The relationships

Lateral Asymmetry and Spatial Difference of Iron Deposition in the Substantia Nigra of Patients with Parkinson Disease Measured with Quantitative Susceptibility Mapping

Editor’s Choice

The authors evaluated 24 patients with Parkinson disease and 24 age- and sex-matched healthy controls who underwent 3T MR imaging with a 3D multiecho gradient-echo sequence. On reconstructed quantitative susceptibility maps they measured the susceptibility values in the anterior, middle, and posterior parts of the substantia nigra, the whole substantia nigra, and other deep gray matter structures in both cerebral hemispheres. Susceptibility in the middle part, the posterior part, and the whole substantia nigra was significantly higher in the more and the less affected hemibrains of patients with Parkinson disease than in the healthy controls. Also, susceptibility was significantly higher in the posterior substantia nigra of the more affected hemibrain.

Abstract

A 59-year-old woman with Parkinson disease. A, QSM, axial section at the level of the basal ganglia. ROIs as large as possible were placed. Areas encircled in red, green, and blue are the caudate nucleus, putamen, and globus pallidus. B, QSM, axial section at the level of the midbrain. The encircled area identifies the red nucleus medial to the substantial nigra.
A 59-year-old woman with Parkinson disease. A, QSM, axial section at the level of the basal ganglia. ROIs as large as possible were placed. Areas encircled in red, green, and blue are the caudate nucleus, putamen, and globus pallidus. B, QSM, axial section at the level of the midbrain. The encircled area identifies the red nucleus medial to the substantial nigra.

BACKGROUND AND PURPOSE

Quantitative susceptibility mapping is useful for assessing iron deposition in the substantia nigra of patients with Parkinson disease. We aimed to determine whether quantitative susceptibility mapping is useful for assessing the lateral asymmetry and spatial difference in iron deposits in the substantia nigra of patients with Parkinson disease.

MATERIALS AND METHODS

Our study population comprised 24 patients with Parkinson disease and 24 age- and sex-matched healthy controls. They underwent 3T MR imaging by using a 3D multiecho gradient-echo sequence. On reconstructed quantitative susceptibility mapping, we measured the susceptibility values in the anterior, middle, and posterior parts of the substantia nigra, the whole substantia nigra, and other deep gray matter structures in both hemibrains. To identify the more and less affected hemibrains in patients

Cerebral Blood Flow Improvement after Indirect Revascularization for Pediatric Moyamoya Disease: A Statistical Analysis of Arterial Spin-Labeling MRI

Editor’s Choice

The authors evaluated 15 children treated by indirect cerebral revascularization with multiple burr-holes between 2011–2013. Arterial spin-labeling MR imaging and T1 sequences were analyzed under SPM8 before and after the operation (3 and 12 months). Group analysis showed statistically significant preoperative hypoperfusion in the MCA territory in the Moyamoya hemispheres and a significant increase of cerebral perfusion in the same territory after revascularization. The authors conclude that SPM analysis of arterial spin-labeling MR imaging offers a noninvasive evaluation of preoperative cerebral hemodynamic impairment and an objective assessment of postoperative improvement in children with Moyamoya disease.

Abstract

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Click image to enlarge

BACKGROUND AND PURPOSE

The severity of Moyamoya disease is generally scaled with conventional angiography and nuclear medicine. Arterial spin-labeling MR imaging is now acknowledged for the noninvasive quantification of cerebral blood flow. This study aimed to analyze CBF modifications with statistical parametric mapping of arterial spin-labeling MR imaging in children undergoing an operation for Moyamoya disease.

MATERIALS AND METHODS

We included 15 children treated by indirect cerebral revascularization with multiple burr-holes between 2011 and 2013. Arterial spin-labeling MR imaging and T1 sequences were then analyzed under SPM8, according to the general linear model, before and after the operation (3 and 12 months). Voxel-based analysis was performed at the group level, comparing all diseased hemispheres with all normal hemispheres and, at the individual level, comparing each patient with a control group.

RESULTS

Group analysis showed statistically significant preoperative hypoperfusion in the MCA territory in the Moyamoya hemispheres and a significant increase of cerebral perfusion in the same territory after revascularization (P < .05 family-wise error–corrected). Before the operation, individual analysis showed significant hypoperfusion for each patient co-localized with the angiographic defect on DSA. All except 1 patient had improvement of CBF after revascularization, correlated with their clinical status.

A Spiral Spin-Echo MR Imaging Technique for Improved Flow Artifact Suppression in T1-Weighted Postcontrast Brain Imaging: A Comparison with Cartesian Turbo Spin-Echo

Editor’s Choice

T1-weighted enhanced brain imaging was performed in 24 pediatric patients comparing the reference Cartesian TSE sequence (2 minutes 30 seconds) with a spiral spin-echo sequence (1 minutes 18 seconds) with similar spatial resolution and coverage. In 23/24 cases, spiral spin-echo was scored better than Cartesian TSE for flow artifact reduction and in 21 cases was superior in subjective preference. The authors demonstrate a relatively simple 2D spiral SE approach in T1-weighted postcontrast brain MR imaging that has minimal flow artifacts in comparison with its 2D Cartesian TSE counterpart.

Abstract

Figure 3, from Li et al. A Spiral Spin-Echo MR Imaging Technique for Improved Flow Artifact Suppression in T1-Weighted Postcontrast Brain Imaging: A Comparison with Cartesian Turbo Spin-Echo
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BACKGROUND AND PURPOSE

A challenge with the T1-weighted postcontrast Cartesian spin-echo and turbo spin-echo brain MR imaging is the presence of flow artifacts. Our aim was to develop a rapid 2D spiral spin-echo sequence for T1-weighted MR imaging with minimal flow artifacts and to compare it with a conventional Cartesian 2D turbo spin-echo sequence.

MATERIALS AND METHODS

T1-weighted brain imaging was performed in 24 pediatric patients. After the administration of intravenous gadolinium contrast agent, a reference Cartesian TSE sequence with a scanning time of 2 minutes 30 seconds was performed, followed by the proposed spiral spin-echo sequence with a scanning time of 1 minutes 18 seconds, with similar spatial resolution and volumetric coverage. The results were reviewed independently and blindly by 3 neuroradiologists. Scores from a 3-point scale were assigned in 3 categories: flow artifact reduction, subjective preference, and lesion conspicuity, if any. The Wilcoxon signed rank test was performed to evaluate the reviewer scores. The t test was used to evaluate the SNR. The Fleiss κ coefficient was calculated to examine interreader agreement.

RESULTS

In 23 cases, spiral spin-echo was scored over Cartesian TSE in flow artifact reduction (P < .001). In 21 cases, spiral spin-echo was rated superior in subjective preference (

Computational Identification of Tumor Anatomic Location Associated with Survival in 2 Large Cohorts of Human Primary Glioblastomas

Editor’s Choice

Preoperative T1 anatomic MR images of 384 patients with glioblastomas were evaluated by an automated computational image-analysis pipeline to determine the anatomic locations of tumor in each patient. Voxel-based differences in tumor location between good and poor survival groups identified in the training cohort were used to classify patients in The Cancer Genome Atlas cohort into 2 brain-location groups, for which clinical features, messenger RNA expression, and copy number changes were compared. Tumors in the right occipitotemporal periventricular white matter were significantly associated with poor survival in both training and test cohorts. Tumors in the right periatrial location were associated with hypoxia pathway enrichment and PDGFRA amplification. The authors conclude that voxel-based location in glioblastoma is associated with patient outcome and may have a potential role for guiding personalized treatment.

Abstract

Figure 1 from Liu et al, Computational Identification of Tumor Anatomic Location Associated with Survival in 2 Large Cohorts of Human Primary Glioblastomas, AJNR 2016
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BACKGROUND AND PURPOSE

Tumor location has been shown to be a significant prognostic factor in patients with glioblastoma. The purpose of this study was to characterize glioblastoma lesions by identifying MR imaging voxel-based tumor location features that are associated with tumor molecular profiles, patient characteristics, and clinical outcomes.

MATERIALS AND METHODS

Preoperative T1 anatomic MR images of 384 patients with glioblastomas were obtained from 2 independent cohorts (n = 253 from the Stanford University Medical Center for training and n = 131 from The Cancer Genome Atlas for validation). An automated computational image-analysis pipeline was developed to determine the anatomic locations of tumor in each patient. Voxel-based differences in tumor location between good (overall survival of >17 months) and poor (overall survival of <11 months) survival groups identified in the training cohort were used to classify patients in The Cancer Genome Atlas cohort into 2 brain-location groups, for which clinical features, messenger RNA expression, and copy number changes were compared to elucidate

Stent-Assisted Coil Embolization of Intracranial Aneurysms: Complications in Acutely Ruptured versus Unruptured Aneurysms

Editor’s Choice

Editor’s Comment

The authors evaluated complications in a cohort of 45 patients with acutely ruptured aneurysms and 47 with unruptured aneurysms. All were treated with stent-assisted coiling. The permanent complication rate in ruptured aneurysms was 11*. Five of 45 patients had an early rebleed from the treated aneurysm after 3–45 days, and in 4 this rebleed was fatal. Thromboembolic complications occurred in 2 patients with unruptured aneurysms. The authors conclude that the complication rate in ruptured aneurysms was 10 times higher than in unruptured aneurysms.

Abstract

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BACKGROUND AND PURPOSE

The use of stents in the setting of SAH is controversial because of concerns about the efficacy and risk of dual antiplatelet therapy. We compare complications of stent-assisted coil embolization in patients with acutely ruptured aneurysms with complications in patients with unruptured aneurysms.

MATERIALS AND METHODS

Between February 2007 and March 2015, 45 acutely ruptured aneurysms and 47 unruptured aneurysms were treated with stent-assisted coiling. Patients with ruptured aneurysms were not pretreated with antiplatelet medication but received intravenous aspirin during the procedure. Thromboembolic events and early rebleeds were recorded.

RESULTS

In ruptured aneurysms, 9 of 45 patients had thromboembolic complications. Four patients remained asymptomatic, 4 developed infarctions, and 1 patient died. The permanent complication rate in ruptured aneurysms was 11% (95% CI, 4%–24%). Five of 45 patients (11%; 95% CI, 4%–24%) had an early rebleed from the treated aneurysm after 3–45 days, and in 4, this rebleed was fatal. In 46 patients with 47 unruptured aneurysms, thromboembolic complications occurred in 2. One patient remained asymptomatic; the other had a thalamus infarction. The complication rate in unruptured aneurysms was 2.2% (1 of 46; 95% CI, 0.01%–12%). No first-time hemorrhages occurred in 46 patients with 47 aneurysms during 6 months of follow-up.

CONCLUSIONS

The complication rate of

MR Elastography Demonstrates Increased Brain Stiffness in Normal Pressure Hydrocephalus

Editor’s Choice

Editor’s Comment

This is a comprehensive group of guidelines for imaging patients with demyelinating disease, from an international group of neurologists and radiologists. Suggestions for MR imaging protocols are given for the brain, for surveillance imaging for progressive multifocal leukoencephalopathy, for spinal cord imaging, and for the orbit. Recommendations are also given for what type of material should be included in the report.

Abstract

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BACKGROUND AND PURPOSE

Normal pressure hydrocephalus is a reversible neurologic disorder characterized by a triad of cognitive impairment, gait abnormality, and urinary incontinence that is commonly treated with ventriculoperitoneal shunt placement. However, multiple overlapping symptoms often make it difficult to differentiate normal pressure hydrocephalus from other types of dementia, and improved diagnostic techniques would help patient management. MR elastography is a novel diagnostic tool that could potentially identify patients with normal pressure hydrocephalus. The purpose of this study was to assess brain stiffness changes in patients with normal pressure hydrocephalus compared with age- and sex-matched cognitively healthy individuals.

MATERIALS AND METHODS

MR elastography was performed on 10 patients with normal pressure hydrocephalus and 21 age- and sex-matched volunteers with no known neurologic disorders. Image acquisition was conducted on a 3T MR imaging scanner. Shear waves with 60-Hz vibration frequency were transmitted into the brain by a pillowlike passive driver. A novel postprocessing technique resistant to noise and edge artifacts was implemented to determine regional brain stiffness. The Wilcoxon rank sum test and linear regression were used for statistical analysis.

RESULTS

A significant increase in stiffness was observed in the cerebrum (P = .001), occipital lobe (P < .001), parietal lobe (P = .001), and the temporal lobe (P = .02) in the normal pressure hydrocephalus group compared with healthy controls. However, no significant difference was noted

Utility and Significance of Gadolinium-Based Contrast Enhancement in Posterior Reversible Encephalopathy Syndrome

Editor’s Choice

Editor’s Comment

The authors report on a cohort of 135 patients with clinically confirmed PRES who received gadolinium-based contrast and evaluate symptoms, etiology, and clinical follow-up. The most common pattern seen was leptomeningeal (17.8*) or leptomeningeal plus cortical (15.6*). No association was found between the presence or pattern of enhancement and any of the variables, which included sex, age, symptoms, blood pressure, and outcome.

Abstract

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BACKGROUND AND PURPOSE

Posterior reversible encephalopathy syndrome is a clinicoradiologic syndrome. Literature regarding associated factors and the prognostic significance of contrast enhancement in posterior reversible encephalopathy syndrome is sparse. This study set out to evaluate an association between the presence of enhancement in posterior reversible encephalopathy syndrome and various clinical factors in a large series of patients with this syndrome.

MATERIALS AND METHODS

From an MR imaging report search that yielded 176 patients with clinically confirmed posterior reversible encephalopathy syndrome between 1997 and 2014, we identified 135 patients who had received gadolinium-based contrast. The presenting symptoms, etiology, clinical follow-up, and maximum systolic and diastolic blood pressures within 1 day of MR imaging were recorded. MRIs were reviewed for parenchymal hemorrhage, MR imaging severity, and the presence and pattern of contrast enhancement. Statistical analyses evaluated a correlation between any clinical features and the presence or pattern of enhancement.

RESULTS

Of 135 included patients (67.4% females; age range, 7–82 years), 59 (43.7%) had contrast enhancement on T1-weighted MR imaging, the most common pattern being leptomeningeal (n = 24, 17.8%) or leptomeningeal plus cortical (n = 21, 15.6%). Clinical outcomes were available in 96 patients. No significant association was found between the presence or pattern of enhancement and any of the variables, including sex, age, symptom, MR imaging severity, blood pressure, or outcome (all P > .05 after Bonferroni correction).