3D T1-weighted Sequence Research Articles

Quantitative MRI adds to neuropsychiatric lupus diagnostics.

Attributing neuropsychiatric manifestations to SLE is often challenging. Brain white matter lesions are frequent in SLE at MRI, but their diagnostic role is unclear. Here, we assessed whether white matter lesions count, volume and distribution measurement can help in the diagnosis of neuropsychiatric systemic lupus erythematosus (NPSLE). Brain dual-echo and 3D T1-weighted sequences were acquired from 32 patients with SLE and 32 healthy controls with a 3 T-scanner and employed to derive T2-hyperintense lesion volume (T2LV), number (T2LN) and probability maps (LPM) using a semi-automatic local thresholding segmentation technique. NPSLE was classified as per the ACR nomenclature, the Italian Society for Rheumatology algorithm and by clinical impression. Clinical descriptors including the SLE International Collaborating Clinics/ACR damage index (SDI) were also recorded. Higher T2LV were observed in SLE vs healthy controls (P<0.001) and in NPSLE vs other SLE (P=0.006). Patients with NPSLE also had higher T2LN (P=0.003) compared with other SLE. In SLE, T2LPM revealed a high prevalence of lesions in the splenium of the corpus callosum, right superior longitudinal fasciculus and right corona radiata. T2LV and T2LN correlated with SLE duration (rho = 0.606; P<0.001 and rho = 0.483; P=0.005, respectively) and age (rho = 0.478; P=0.006 and rho = 0.362; P = 0.042, respectively). T2LV also correlated with SDI (rho = 0.352; P=0.048). SLE patients with fatigue had lower T2LN (P=0.038) compared with patients without fatigue. Thresholds of T2LV ≥ 0.423 cm3 or of T2LN ≥ 12 were associated with definite NPSLE and improved the classification of patients with possible NPSLE per clinical impression. Brain white matter lesions (WML) quantitation adds to NPSLE diagnostics.

Determination of skeletal tumor extent: is an isotropic T1-weighted 3D sequence adequate?

To test the hypothesis that an accelerated, T1-weighted 3D CAIPIRINHA SPACE sequence with isotropic voxel size offers a similar performance to conventional T1-weighted 2D TSE (turbo spin echo) for the evaluation of bone tumor extent and characteristics. Thirty-four patients who underwent 3-T MRI with 3DT1 (CAIPIRINHA SPACE TSE) and 2DT1 (TSE) were included. Sequence acquisition time was reported. Two radiologists independently evaluated each technique for tumor location, size/length, tumor-to-joint distance, signal intensity, margin/extraosseous extension, and signal-to-noise (SNR) and contrast-to-noise (CNR) ratios. Tumors were located in long (20/36, 55.5%) and pelvic (16/36, 44.4%) bones. 3DT1 sequence required an average acquisition time of 235 s (± 42 s, range 156-372), while two plane 2DT1 sequences combined (coronal and axial) had an average acquisition time of 381 s (± 73 s, range 312-523). There was no difference in the measurements of tumor length and tumor-to-joint distance (p = 0.95) between 3DT1 and 2DT1 images. Tumors were hypointense (17/36, 47.2% vs 17/36, 47.2%), isointense (12/36, 33.3% vs 12/36, 33.3%), or hyperintense (7/36, 19.4% vs 7/36, 19.4%) on 3DT1 vs 2DT1, respectively. Assessment of tumor margins and extraosseous extension was similar, and there was no difference in tumor SNR or CNR (p > 0.05). An accelerated 3D CAIPIRINHA SPACE T1 sequence provides comparable assessments of intramedullary bone tumor extent and similar tumor characteristics to conventional 2DT1 MRI. For the assessment of bone tumors, the isotropic volume acquisition and multiplanar reformation capability of the 3DT1 datasets can obviate the need for 2DT1 acquisitions in multiple planes. • 3DT1 offers an equivalent performance to 2DT1 for the assessment of bone tumor characteristics, with faster and higher resolution capability, obviating the need for acquiring 2DT1 in multiple planes. • There was no difference in the measurements of tumor length and tumor-to-joint distance obtained on 3DT1 and 2DT1 images. • There was no difference in signal-to-noise ratio (SNR) or contrast-to-noise ratio (CNR) measures between 3DT1 and 2DT1.

Gadolinium-Enhanced 3D T1-Weighted Black-Blood MR Imaging for the Detection of Acute Optic Neuritis.

A 3D T1-weighted black-blood sequence was recently shown to improve the detection of contrast-enhancing lesions in the brain in patients with MS compared with a 3D T1-weighted MPRAGE sequence. We compared a contrast-enhanced 3D T1-weighted black-blood sequence with a dedicated orbital contrast-enhanced T1-weighted Dixon sequence in patients with acute optic neuritis. MR imaging data (3T) of 51 patients showing symptoms of acute optic neuritis were analyzed retrospectively, including whole-brain contrast-enhanced 3D T1-weighted black-blood and dedicated orbital coronal 2D or 3D contrast-enhanced T1-weighted Dixon sequences. Two neuroradiologists assessed the images for overall image quality, artifacts, diagnostic confidence, and visual contrast enhancement. Furthermore, the standardized contrast-to-noise ratio was calculated. The final diagnosis of acute optic neuritis was established on the basis of clinical presentation, visually evoked potentials, and optical coherence tomography. Thirty of 51 patients were diagnosed with acute optic neuritis. Of those, 21 showed contrast-enhancing lesions in the optic nerves, similarly detectable on contrast-enhanced T1-weighted Dixon and contrast-enhanced T1-weighted black-blood images. Thus, the accuracy for each sequence was identical, with a resulting sensitivity of 70% and specificity of 90% or 100% (depending on the reader). Overall image quality, diagnostic confidence, visual contrast enhancement, and artifacts were rated similarly in contrast-enhanced 3D T1-weighted black-blood and dedicated orbital contrast-enhanced T1-weighted Dixon sequences. There was no significant difference (P = .27) in the mean standardized contrast-to-noise ratio between contrast-enhanced T1-weighted black-blood (1.76 ± 1.07) and contrast-enhanced T1-weighted Dixon (2.29 ± 2.49) sequences. Contrast-enhanced 3D T1-weighted black-blood imaging is comparable in accuracy and qualitative/quantitative features with dedicated orbital contrast-enhanced T1-weighted Dixon imaging for the detection of acute optic neuritis. Therefore, when used, it has the potential to considerably shorten total patient imaging time.

MR\xa0imaging by 3D T1-weighted black blood sequences may improve delineation of therapy-naive high-grade gliomas

ObjectivesTo investigate the value of contrast-enhanced (CE) turbo spin echo black blood (BB) sequences for imaging of therapy-naive high-grade gliomas (HGGs).MethodsConsecutive patients with histopathologically confirmed World Health Organization (WHO) grade III or IV gliomas and no oncological treatment prior to index imaging (March 2019 to January 2020) were retrospectively included. Magnetic resonance imaging (MRI) at 3 Tesla comprised CE BB and CE turbo field echo (TFE) sequences. The lack/presence of tumor-related contrast enhancement and satellite lesions were evaluated by two readers. Sharper delineation of tumor boundaries (1, bad; 2, intermediate; 3, good delineation) and vaster expansion of HGGs into the adjacent brain parenchyma on CE BB imaging were the endpoints. Furthermore, contrast-to-noise ratios (CNRs) were calculated and compared between sequences.ResultsFifty-four patients were included (mean age: 61.2 ± 15.9 years, 64% male). The vast majority of HGGs (51/54) showed contrast enhancement in both sequences, while two HGGs as well as one of six detected satellite lesions were depicted in CE BB imaging only. Tumor boundaries were significantly sharper (R1: 2.43 ± 0.71 vs. 2.73 ± 0.62, p < 0.001; R2: 2.44 ± 0.74 vs. 2.77 ± 0.60, p = 0.001), while the spread of HGGs into the adjacent parenchyma was larger when considering CE BB sequences according to both readers (larger spread in CE BB sequences: R1: 23 patients; R2: 20 patients). The CNR for CE BB sequences significantly exceeded that of CE TFE sequences (43.4 ± 27.1 vs. 32.5 ± 25.0, p = 0.0028).ConclusionsOur findings suggest that BB imaging may considerably improve delineation of therapy-naive HGGs when compared with established TFE imaging. Thus, CE BB sequences might supplement MRI protocols for brain tumors.Key Points• This study investigated contrast-enhanced (CE) T1-weighted black blood (BB) sequences for improved MRI in patients with therapy-naive high-grade gliomas (HGGs).• Compared with conventionally used turbo field echo (TFE) sequences, CE BB sequences depicted tumor boundaries and spread of HGGs into adjacent parenchyma considerably better, which also showed higher CNRs.• Two enhancing tumor masses and one satellite lesion were exclusively identified in CE BB sequences, but remained undetected in conventionally used CE TFE sequences.

The cerebellum in idiopathic cervical dystonia: A specific pattern of structural abnormalities?

IntroductionIn recent years, cerebellar abnormalities have gained increasing attention as possible physiopathological substratum of idiopathic cervical dystonia (ICD), but a consistent pattern of cerebellar structural modifications has not yet been established. We systematically investigated the presence of volumetric alterations of cerebellar gray (GM) and white matter (WM) in ICD patients, as well as their clinical relevance. MethodsIn this two-centers prospective cross-sectional study, from May 2013 to December 2017, 27 patients with ICD and 27 age- and sex-comparable healthy controls underwent brain MRI including 3D T1-weighted sequences for volumetric analyses. Between-group differences in terms of gray matter and cerebellar peduncles volumes were investigated using both region of interest (ROI)-based and voxel-based approaches using the SUIT tool (SPM12), and significant volumetric changes were correlated with clinical impairment (as measured with the Tsui score) and presence of tremor. ResultsICD patients showed significant volumetric reduction of cerebellar GM in the anterior lobe and lobule VI, resulting from both ROI-based (p ≤ 0.009) and voxel-based (p ≤ 0.04) analyses, while small clusters of reduced WM volume were found in the right cerebellum and left midbrain (p = 0.04), along with reduced volume of the bilateral superior (p = 0.04) and middle (p = 0.03) cerebellar peduncles. Furthermore, higher middle cerebellar peduncles volume was associated with the presence of tremor (p = 0.04). ConclusionOur data show evidence of a specific pattern of cerebellar structural abnormalities in ICD patients, with volume loss mainly involving cortical GM regions related to the somatotopic representation of the affected body parts and, to a lesser extent, cerebellar peduncles.

Inter-scanner reproducibility of brain volumetry: influence of automated brain segmentation software

BackgroundThe inter-scanner reproducibility of brain volumetry is important in multi-site neuroimaging studies, where the reliability of automated brain segmentation (ABS) tools plays an important role. This study aimed to evaluate the influence of ABS tools on the consistency and reproducibility of the quantified brain volumetry from different scanners.MethodsWe included fifteen healthy volunteers who were scanned with 3D isotropic brain T1-weighted sequence on three different 3.0 Tesla MRI scanners (GE, Siemens and Philips). For each individual, the time span between image acquisitions on different scanners was limited to 1 h. All the T1-weighted images were processed with FreeSurfer v6.0, FSL v5.0 and AccuBrain® with default settings to obtain volumetry of brain tissues (e.g. gray matter) and substructures (e.g. basal ganglia structures) if available. Coefficient of variation (CV) was calculated to test inter-scanner variability in brain volumetry of various structures as quantified by these ABS tools.ResultsThe mean inter-scanner CV values per brain structure among three MRI scanners ranged from 6.946 to 12.29% (mean, 9.577%) for FreeSurfer, 7.245 to 20.98% (mean, 12.60%) for FSL and 1.348 to 8.800% (mean value, 3.546%) for AccuBrain®. In addition, AccuBrain® and FreeSurfer achieved the lowest mean values of region-specific CV between GE and Siemens scanners (from 0.818 to 5.958% for AccuBrain®, and from 0.903 to 7.977% for FreeSurfer), while FSL-FIRST had the lowest mean values of region-specific CV between GE and Philips scanners (from 2.603 to 16.310%). AccuBrain® also had the lowest mean values of region-specific CV between Siemens and Philips scanners (from 1.138 to 6.615%).ConclusionThere is a large discrepancy in the inter-scanner reproducibility of brain volumetry when using different processing software. Image acquisition protocols and selection of ABS tool for brain volumetry quantification have impact on the robustness of results in multi-site studies.

Knee osteochondral junction imaging using a fast 3D T1-weighted ultrashort echo time cones sequence at 3T

The osteochondral junction (OCJ) of the knee joint is comprised of multiple tissue components, including a portion of the deep layer cartilage, calcified cartilage, and subchondral bone. The OCJ is of increasing radiological interest as it may be relevant in the early pathogenesis of osteoarthritis (OA). Due to its short transverse relaxation, the OCJ is invisible to clinical MR sequences. The purpose of this study was to develop a fast 3D T1-weighted ultrashort echo time cones sequence with fat saturation (FS-UTE-Cones) for high resolution and high contrast imaging of the OCJ on a clinical 3T scanner. First, numerical simulations were performed to investigate how the flip angle affected the signal intensities and contrasts of both short and long T1 tissues. The results from these simulations demonstrated that higher short T1 contrast could be achieved with higher flip angle. Next, T1 relaxation was measured for the different layers of a human patellar cartilage sample, and the results showed that the deepest layer had a significantly shorter T1 value than other layers. Finally, a healthy knee joint was scanned with different flip angles and the OCJ was highlighted in the T1-weighted FS-UTE-Cones sequence using a flip angle greater than 20°. The clinical T2-weighted and proton density-weighted FSE sequences were also included for comparison, revealing a dark OCJ region. Representative T1-weighted FS-UTE-Cones images of the whole knee of a healthy volunteer showed high signal intensity bands in the OCJ regions of the patella, femur, and tibia. On the other hand, T1-weighted FS-UTE-Cones imaging of the knee joints of OA patients revealed regions with reduction or loss of these high signal intensity bands in the OCJ regions, indicating abnormal OCJ tissue composition. The proposed 3D T1-weighted FS-UTE-Cones sequence with a 3-min scan time may be very useful for demonstrating the involvement of the OCJ regions in early OA.

Comparison between 1.5- and 3-T Magnetic Resonance Acquisitions for Direct Targeting Stereotactic Procedures for Deep Brain Stimulation: A Phantom Study

Introduction: Deep brain stimulation (DBS) is a well-established treatment for movement disorders. High magnetic fields could have an impact on distortion. We evaluated 1.5- and 3-T magnetic resonance imaging (MRI) sequences for accuracy, precision, and trueness of our MRI-guided direct targeting protocol. Methods: Effects of distortion on MR sequences (T1- and T2-weighted sequences) can be evaluated using a dedicated phantom (Elekta). Field strength capabilities were assessed on Siemens Avanto (1.5 T) and Skyra (3 T) scanners. We assessed the precision of our stereotactic MRI-guided procedure. Results: We focused on the risk of error due to a high field strength. Error values on the localizer box were between 0.4 and 0.7 mm at 1.5 T and between 0.6 and 2 mm at 3 T. The most accurate 1.5-T sequence is the 3D FLASH T1-weighted sequence, which had an accuracy value of 0.6 mm. At 3 T, the accuracy value of the isotropic 3D FLASH T1-weighted sequence was 1.6 mm. Conclusion: Given the millimetric size of stereotactic targets and electrodes, lead implantation for neuromodulation therapy needs to be accurate. We demonstrate that 3-T imaging could not be used for stereotaxy in our MRI-guided direct targeting protocol because of a risk of error induced by distortion.

Applicator visualization using ultrashort echo time MRI for high-dose-rate endorectal brachytherapy

PurposeThe individual channels in an endorectal applicator for high-dose-rate endorectal brachytherapy are not visible on standard MRI sequences. The aim of this study was to test whether an ultrashort echo time (UTE) MRI sequence could be used to visualize the individual channels to enable MR-only treatment planning for rectal cancer. Methods and MaterialsWe used a radial three-dimensional (3D) UTE pulse sequence and acquired images of phantoms and two patients with rectal cancer. We rigidly registered a UTE image and CT scan of an applicator phantom, based on the outline of the applicator. One observer compared channel positions on the UTE image and CT scan in five slices spaced 25 mm apart. To quantify geometric distortions, we scanned a commercial 3D geometric quality assurance phantom and calculated the difference between detected marker positions on the UTE image and corresponding marker positions on two 3D T1-weighted images with opposing readout directions. ResultsOn the UTE images, there is sufficient contrast to discern the individual channels. The difference in channel positions on the UTE image compared with the CT was on average −0.1 ± 0.1 mm (left-right) and 0.1 ± 0.3 mm (anteroposterior). After rigid registration to the 3D T1-weighted sequences, the residual 95th percentile of the geometric distortion inside a 550-mm-diameter sphere was 1.0 mm (left-right), 0.9 mm (anteroposterior), and 0.9 mm (craniocaudal). ConclusionsWith a UTE sequence, the endorectal applicator and individual channels can be adequately visualized in both phantom and patients. The geometrical fidelity is within an acceptable range.

Hypoglossal Nerve Lesions: The Role of a 3D IR-Prepped Fast SPGR High-Resolution 3T MRI Sequence.

To assess a 3D high-resolution IR-prepped fast SPGR high-resolution MRI sequence for evaluating hypoglossal nerve lesions. The clinical data of 8 patients with hypoglossal nerve lesions admitted from December 2011 to February 2016 were retrospectively analyzed. MRI included contrast-enhanced conventional sequences and a 3D IR-prepped fast SPGR high-resolution T1-weighted (BRAVO) MRI sequence at 3T. Eight patients had hypoglossal lesions detected by MRI. Conventional enhanced scanning could not clearly display the hypoglossal nerve and canal, while the enhanced 3D high-resolution sequence could. In addition, multiple planar reconstruction clearly displayed the hypoglossal nerve, hypoglossal canal, and lesions in multiple planes. Compared with conventional MRI, we show superior results from an advanced sequence to improve image quality in characterizing hypoglossal nerve lesions.

Prediction of post-hepatectomy liver failure using gadoxetic acid-enhanced magnetic resonance imaging for hepatocellular carcinoma with portal vein invasion

PurposeAccurate prediction of post-hepatectomy liver failure (PHLF) is important in advanced hepatocellular carcinoma (HCC). We aimed to retrospectively evaluate the utility of gadoxetic acid-enhanced MRI for predicting PHLF in patients who underwent anatomic hepatectomy for HCC with portal vein invasion. MethodsForty-one patients (32 men, 9 women) were included. Hepatobiliary-phase MR images were acquired 20 min after injection of gadoxetic acid using a 3D fat-suppressed T1-weighted spoiled gradient-echo sequence. Liver-spleen ratio (LSR), remnant hepatocellular uptake index (rHUI), and HUI were calculated. The severity of PHLF was defined according to the International Study Group of Liver Surgery. Differences in LSR between the resected liver and the remnant liver, and HUI and rHUI/HUI between no/mild and severe PHLF were compared using the Wilcoxon signed-rank test and Wilcoxon rank-sum test, respectively. Univariate and multivariate logistic regression analyses were performed to identify predictors of severe PHLF. Areas under the receiver operating characteristic curves (AUCs) of rHUI and rHUI/HUI were calculated for predicting severe PHLF. ResultsNine patients developed severe PHLF. LSR of the remnant liver was significantly higher than that of the resected liver (P < 0.001). Severe PHLF demonstrated significantly lower rHUI (P < 0.001) and rHUI/HUI (P < 0.001) compared with no/mild PHLF. Multivariate logistic regression analysis showed that decreased rHUI (P = 0.012, AUC=0.885) and rHUI/HUI (P = 0.002, AUC=0.852) were independent predictors of severe PHLF. ConclusionGadoxetic acid-enhanced MRI can be a promising noninvasive examination for assessing global and regional liver function, allowing estimation of the functional liver remnant and accurate prediction of severe PHLF before hepatic resection.

Spiral 3-Dimensional T1-Weighted Turbo Field Echo: Increased Speed for Magnetization-Prepared Gradient Echo Brain Magnetic Resonance Imaging.

Spiral magnetic resonance imaging acquisition may enable improved image quality and higher scan speeds than Cartesian trajectories. We tested the performance of four 3D T1-weighted (T1w) TFE sequences (magnetization-prepared gradient echo magnetic resonance sequence) with isotropic spatial resolution for brain imaging at 1.5 T in a clinical patient cohort based on qualitative and quantitative image quality metrics. Two prototypical spiral TFE sequences (spiral 1.0 and spiral 0.85) and a Cartesian compressed sensing technology accelerated TFE sequence (CS 2.5; acceleration factor of 2.5) were compared with a conventional (reference standard) Cartesian parallel imaging accelerated TFE sequence (SENSE; acceleration factor of 1.8). The SENSE (5:52 minutes), CS 2.5 (3:17 minutes), and spiral 1.0 (2:16 minutes) sequences all had identical spatial resolutions (1.0 mm). The spiral 0.85 (3:47 minutes) had a higher spatial resolution (0.85 mm). The 4 TFE sequences were acquired in 41 patients (20 with and 21 without contrast media). Three readers rated qualitative image quality (12 categories) and selected their preferred sequence for each patient. Two readers performed quantitative analysis whereby 6 metrics were derived: contrast-to-noise ratio for white and gray matter (CNRWM/GM), contrast ratio for gray matter-CSF (CRGM/CSF), and white matter-CSF (CRWM/CSF); and coefficient of variations for gray matter (CVGM), white matter (CVWM), and CSF (CVCSF). Friedman tests with post hoc Nemenyi tests, exact binomial tests, analysis of variance with post hoc Dunnett tests, and Krippendorff alphas were computed. Concerning qualitative analysis, the CS 2.5 sequence significantly outperformed the SENSE in 4/1 (with/without contrast) categories, whereas the spiral 1.0 and spiral 0.85 showed significantly improved scores in 10/9and 7/7 categories, respectively (P's < 0.001-0.039). The spiral 1.0 was most frequently selected as the preferred sequence (reader 1, 10/15 times; reader 2, 9/12 times; reader 3, 11/13times [with/without contrast]). Interreader agreement ranged from substantial to almost perfect (alpha = 0.615-0.997). Concerning quantitative analysis, compared with the SENSE, the CS 2.5 had significantly better scores in 2 categories (CVWM, CVCSF) and worse scores in 2 categories (CRGM/CSF, CRWM/CSF), the spiral 1.0 had significantly improved scores in 4 categories (CNRWM/GM, CRGM/CSF, CRWM/CSF, CVWM), and the spiral 0.85 had significantly better scores in 2 categories (CRGM/CSF, CRWM/CSF). Spiral T1w TFE sequences may deliver high-quality clinical brain imaging, thus matching the performance of conventional parallel imaging accelerated T1w TFEs. Imaging can be performed at scan times as short as 2:16 minutes per sequence (61.4% scan time reduction compared with SENSE). Optionally, spiral imaging enables increased spatial resolution while maintaining the scan time of a Cartesian-based acquisition schema.

Clinical implementation of MRI-based organs-at-risk auto-segmentation with convolutional networks for prostate radiotherapy

BackgroundStructure delineation is a necessary, yet time-consuming manual procedure in radiotherapy. Recently, convolutional neural networks have been proposed to speed-up and automatise this procedure, obtaining promising results. With the advent of magnetic resonance imaging (MRI)-guided radiotherapy, MR-based segmentation is becoming increasingly relevant. However, the majority of the studies investigated automatic contouring based on computed tomography (CT).PurposeIn this study, we investigate the feasibility of clinical use of deep learning-based automatic OARs delineation on MRI.Materials and methodsWe included 150 patients diagnosed with prostate cancer who underwent MR-only radiotherapy. A three-dimensional (3D) T1-weighted dual spoiled gradient-recalled echo sequence was acquired with 3T MRI for the generation of the synthetic-CT. The first 48 patients were included in a feasibility study training two 3D convolutional networks called DeepMedic and dense V-net (dV-net) to segment bladder, rectum and femurs. A research version of an atlas-based software was considered for comparison. Dice similarity coefficient, 95% Hausdorff distances (HD95), and mean distances were calculated against clinical delineations. For eight patients, an expert RTT scored the quality of the contouring for all the three methods. A choice among the three approaches was made, and the chosen approach was retrained on 97 patients and implemented for automatic use in the clinical workflow. For the successive 53 patients, Dice, HD95 and mean distances were calculated against the clinically used delineations.ResultsDeepMedic, dV-net and the atlas-based software generated contours in 60 s, 4 s and 10-15 min, respectively. Performances were higher for both the networks compared to the atlas-based software. The qualitative analysis demonstrated that delineation from DeepMedic required fewer adaptations, followed by dV-net and the atlas-based software. DeepMedic was clinically implemented. After retraining DeepMedic and testing on the successive patients, the performances slightly improved.ConclusionHigh conformality for OARs delineation was achieved with two in-house trained networks, obtaining a significant speed-up of the delineation procedure. Comparison of different approaches has been performed leading to the succesful adoption of one of the neural networks, DeepMedic, in the clinical workflow. DeepMedic maintained in a clinical setting the accuracy obtained in the feasibility study.

Inner SPACE: 400-Micron Isotropic Resolution MRI of the Human Brain.

ObjectivesClinically relevant neuroanatomy is challenging to teach, learn and remember since many functionally important structures are visualized best using histology stains from serial 2D planar sections of the brain. In clinical patients, the locations of specific structures then must be inferred from spatial position and surface anatomy. A 3D MRI dataset of neuroanatomy has several advantages including simultaneous multi-planar visualization in the same brain, direct end-user manipulation of the data and image contrast identical to clinical MRI. We created 3D MRI datasets of the postmortem brain with high spatial and contrast resolution for simultaneous multi-planar visualization of complex neuroanatomy.Materials and MethodsWhole human brains (N = 6) were immersion-fixed in 4% formaldehyde for 4 weeks, then washed continuously in water for 48 h. The brains were imaged on a clinical 3-T MRI scanner with a 64-channel head and neck coil using a 3D T2-weighted sequence with 400-micron isotropic resolution (voxel = 0.064 mm3; time = 7 h). Besides resolution, this sequence has multiple adjustments to improve contrast compared to a clinical protocol, including 93% reduced turbo factor and 77% reduced effective echo time.ResultsThis MRI microscopy protocol provided excellent contrast resolution of small nuclei and internal myelinated pathways within the basal ganglia, thalamus, brainstem, and cerebellum. Contrast was sufficient to visualize the presence and variation of horizontal layers in the cerebral cortex. 3D isotropic resolution datasets facilitated simultaneous multi-planar visualization and efficient production of specific tailored oblique image orientations to improve understanding of complex neuroanatomy.ConclusionWe created an unlabeled high-resolution digital 3D MRI dataset of neuroanatomy as an online resource for readers to download, manipulate, annotate and use for clinical practice, research, and teaching that is complementary to traditional histology-based atlases. Digital MRI contrast is quantifiable, reproducible across brains and could help validate novel MRI strategies for in vivo structure visualization.

Diffusion tensor based forearm nerve tractography in 1.5 T MRI

Diffusion tensor imaging (DTI) is a magnetic resonance imaging (MRI) method for efficient nerve pathways visualization. DTI, particularly of peripheral nerves, is commonly performed in 3 T scanners. An often more accessible 1.5 T scanners are less likely to be chosen for DTI examinations due to generally lower image quality. Novel radiofrequency (RF) coils can help improve the signal to noise ratio in MRI and thus improve image quality. This study preliminary results of the feasibility and outcomes assessment of DTI-based tractography of the forearm nerves employing a novel coil design in 1.5 T scanners. The proposed scanning protocol includes the use of a metamaterial-inspired RF coil, a common DTI pulse sequence and a 3D T1-weighted morphological reference pulse sequence. The protocol is tested on three healthy volunteers. Two tract bundles corresponding to median and ulnar nerves of the forearm are reliably reconstructed in all subjects. The results show that with an appropriate choice of RF coil and pulse sequence parameters forearm DTI studies can be performed in 1.5 T scanners with sufficient quality making such examination more accessible for clinical use.

Detection of brain metastases using alternative magnetic resonance imaging sequences: a comparison between SPACE and VIBE sequences

Abstract Background Accurate identification of brain metastases is crucial for cancer treatment. Objectives To compare the ability to detect brain metastases of two alternative types of contrast-enhanced three-dimensional (3D) T1-weighted sequences called SPACE (Sampling Perfection with Application optimized Contrasts using different flip angle Evolutions) and VIBE (Volumetric Interpolated Brain Sequence) on magnetic resonance imaging (MRI) at 3 tesla. Methods Between April 2017 and February 2018, 27 consecutive adult Thai patients with a total number of 424 brain metastases were retrospectively included. The patients underwent both contrast-enhanced 3D T1-weighted SPACE and 3D T1-weighted VIBE MRI sequences at 3 tesla. Two neuroradiology experts independently reviewed the images to determine the number of enhancing lesions on each sequence. Wilcoxon signed rank test was used to compare the difference between the numbers of detectable parenchymal enhancing lesions. Interobserver reliability was calculated using intraclass correlation. Results 3D T1-weighted SPACE detected more parenchymal enhancing lesions than 3D T1-weighted VIBE (424 vs. 378 lesions, median 6 vs. 5, P = 0.008). Fifteen patients (55.6%) had equal number of parenchymal enhancing lesions between two sequences. 3D T1-weighted SPACE detected more parenchymal enhancing lesions (up to 9 more lesions) in 10 patients (37%), while 3D T1-weighted VIBE detected more enhancing lesions (up to 2 more lesions) in 2 patients (7.4%). Interobserver reliability between the readers was excellent. Conclusion Contrast-enhanced 3D T1-weighted SPACE sequence demonstrates a higher ability to detect brain metastases than contrast-enhanced 3D T1-weighted VIBE sequence at 3 tesla.

Impaired cerebral blood flow in type 2 diabetes mellitus – A comparative study with subjective cognitive decline, vascular dementia and Alzheimer’s disease subjects

The link between non-demented type 2 diabetes mellitus (T2DM) and different types of cognitive impairment is controversial. By controlling for co-morbidities such as cerebral macrovascular and microvascular changes, cerebral atrophy, amyloid burden, hypertension or hyperlipidemia, the current study investigated the cerebral blood flow of T2DM individuals as compared to cognitively impaired subjects recruited from a memory clinic.15 healthy control (71.8 ± 6.1 years), 18 T2DM (62.5 ± 3.7 years), as well as 8 Subjective Cognitive Decline (69.5 ± 7.5 years), 12 Vascular Dementia (79.3 ± 4.2 years) and 17 Alzheimer’s Disease (75.1 ± 8.2 years) underwent multi-parametric MRI brain scanning. Subjects with T2DM and from the memory clinic also had 18-F Flutametamol PET-CT scanning to look for any amyloid burden. Pseudocontinuous Arterial Spin Labeling (PCASL), MR Angiography Head, 3D FLAIR and 3D T1-weighted sequences were used to quantify cerebral blood flow, cerebrovascular changes, white matter hyperintensities and brain atrophy respectively. Vascular risk factors were retrieved from the medical records. The 37 subjects from memory clinic were classified into subjective cognitive decline (SCD), vascular dementia (VD) and Alzheimer’s disease (AD) subgroups by a multi-disciplinary panel consisting of a neuroradiologist, and 2 geriatricians.Absolute cortical CBF in our cohort of T2DM, SCD, VD and AD was significantly decreased (p < 0.01) as compared to healthy controls (HC) in both whole brain and eight paired brain regions, after age, normalized grey matter volume and gender adjustment and Bonferroni correction.Subgroup analysis between T2DM, SCD, VD, and AD revealed that CBF of T2DM was not significantly different from AD, VD or SCD. By controlling for co-morbidities, impaired cortical CBF in T2DM was not related to microangiopathy or amyloid deposition, but to the interaction of triple risk factors (such as diabetes mellitus, hypertension, and hyperlipidemia).There was statistically significant negative correlation (p ≤ 0.05) between adjusted CBF and HbA1c in all brain regions of T2DM and HC (with partial correlation ranging from −0.30 to −0.46).Taken together, altered cerebral blood flow in T2DM might be related to disruption of cerebrovascular autoregulation related to vascular risk factors, and such oligemia occurred before clinical manifestation due to altered glycemic control.

ANALYSIS OF FATTY DEGENERATION OF THE TRAPEZIUS MUSCLE AFTER USE OF ACCESSORY NERVE.

ABSTRACTObjective: To investigate, through magnetic resonance imaging, the occurrence of fatty degeneration of the trapezius in adult patients undergoing nerve transfer procedure, using the spinal accessory nerve.Methods: A total of 13 patients meeting the criteria of unilateral brachial plexus injury and more than one year of postoperative care after nerve transfer surgery underwent an MRI scan of the trapezius. A T1-weighted 3D sequence was used, with the IDEAL technique using 8.0 mm cut thickness, 8.0 mm cut spacing, TR of 100 ms, TE of 3.45 ms, flip angle of 10 degrees, 20 cuts, on the sagittal plane. The images of the upper, transverse and lower parts of the trapezius muscle were then classified according to the degree of fatty degeneration, compared with the contralateral side, using the Goutallier score.Results: For the upper trapezius there was a change of the degeneration state in 23% (p = 0.083), for the transverse section there was a change in 84.6% (p = 0.003), for the lower one there was a change in 92.3% (p = 0.002).Conclusion: The upper trapezius did not undergo significant degeneration after transfer. The lower and transverse trapezius suffered fatty degeneration in most patients, indicating severe functional impairment. Level of Evidence IV, Case series.

Emerging Use of Ultra-High-Field 7T MRI in the Study of Intracranial Vascularity: State of the Field and Future Directions.

Cerebrovascular disease is a major source of mortality that commonly requires neurosurgical intervention. MR imaging is the preferred technique for imaging cerebrovascular structures, as well as regions of pathology that include microbleeds and ischemia. Advanced MR imaging sequences such as time-of-flight, susceptibility-weighted imaging, and 3D T2-weighted sequences have demonstrated excellent depiction of arterial and venous structures with and without contrast administration. While the advantages of 3T compared with 1.5T have been described, the role of ultra-high-field (7T) MR imaging in neurovascular imaging remains poorly understood. In the present review, we examine emerging neurosurgical applications of 7T MR imaging in vascular imaging of diverse conditions and discuss current limitations and future directions for this technique.

P1894Serum light-chain neurofilament is associated with brain atrophy in patients with atrial fibrillation

Abstract Background and aims There is emerging evidence that atrial fibrillation (AF) is associated with cognitive dysfunction, increased risk for dementia and reduced brain volume independent of stroke, but the underlying mechanisms of these associations remain unclear. Here, we investigated the association of serum light-chain neurofilament (sNfL), a neuroaxonal injury biomarker, with brain atrophy in AF patients. Methods Explorative analysis from the Swiss-AF cohort study, a multicenter prospective observationalstudy which recruited patients aged ≥45 years with documented AF (NCT02105844). In baseline blood samples, sNfL concentrations were measured in duplicates using a single-molecule array assay. Brain MRI was obtained at baseline and at two years using a standardized protocol including a 3D T1-weighted MPRAGE sequence, on which Structural Image Evaluation using Normalization of Atrophy (SIENA) with optimized parameters for brain extraction was applied to calculate the two-year percentage whole brain volume change (PBVC). Results We included 245 Swiss-AF patients (median age 73, 73% male). Two-year PBVC was significantly associated with baseline sNfL in linear regression, with a 0.09% whole brain volume decrease per 10 pg/ml sNfL increase (95% CI [0.05–0.13], p&lt;0.001). This association remained significant after adjustment for age, history of stroke and other vascular risk factors. Neurofilament and brain atrophy Conclusion Increasing baseline sNfL was predictive of higher two-year brain atrophy rates independent of stroke history in AF patients. This association might reflect a chronic neurodegenerative process in AF. Acknowledgement/Funding Swiss National Science Foundation