scholarly journals A High-Resolution Interactive Atlas of the Human Brainstem Using Magnetic Resonance Histology

Neurosurgery ◽  
2020 ◽  
Vol 67 (Supplement_1) ◽  
Author(s):  
Syed M Adil ◽  
Evan Calabrese ◽  
Lefko T Charalambous ◽  
James Cook ◽  
Shervin Rahimpour ◽  
...  
Keyword(s):  
White Matter ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Spatial Resolution ◽  
7 Tesla ◽  
Acquisition Time ◽  
Superior Cerebellar Peduncle ◽  
Corticospinal Tracts ◽  
Custom Made ◽  
And Diffusion

Abstract INTRODUCTION Traditional atlases of the human brainstem are limited by the inflexible, sparsely-sampled, two-dimensional nature of histology or the low spatial resolution of magnetic resonance imaging (MRI). Magnetic resonance histology (MRH) uses postmortem high-resolution MRI to circumvent the challenges associated with both modalities. METHODS A human brainstem specimen extending from the rostral diencephalon through the caudal medulla was removed from a 65-year-old male within 24 hours of death. The specimen was formalin-fixed for two weeks, then rehydrated and placed in a custom-made MRI compatible tube and immersed in buffered liquid fluorocarbon. MRI was performed in a 7-Tesla machine with 120 unique diffusion directions. Acquisition time for anatomic and diffusion images were 14 hours and 208 hours, respectively. Segmentation was performed manually. Deterministic fiber tractography was done using strategically chosen regions of interest and avoidance, with manual editing using expert knowledge of human neuroanatomy. RESULTS Anatomic and diffusion images were rendered with isotropic resolutions of 50 μm and 200 μm, respectively. Spatial resolution was high enough to visualize individual fasciculi of the descending corticospinal tracts intercalated between the transverse pontocerebellar fibers. Ninety different structures were segmented and 11 different fiber bundles were rendered with tractography. Angular resolution was high enough to visualize crossing fibers, such as those of the superior cerebellar peduncle. Both gray and white matter can be visualized in 3D simultaneously, such as the subthalamic nuclei and corticospinal tracts, as may be used in deep brain stimulation. CONCLUSION We used MRH to enable unprecedented resolution in digital imaging of the human brainstem and adjacent diencephalic structures, and we then performed comprehensive segmentation and tractography to render an interactive, three-dimensional atlas of both gray and white matter. This atlas has immediate applications in neuroanatomical study and education, with the potential for future neurosurgical applications in enhancing neurosurgical planning through “safe” zones of entry into the human brainstem. We are currently building the computer infrastructure to make this atlas publicly-available.

scholarly journals Fast high-resolution metabolic imaging of acute stroke with 3D magnetic resonance spectroscopy

Brain ◽  
2020 ◽  
Vol 143 (11) ◽  
pp. 3225-3233
Author(s):  
Yao Li ◽  
Tianyao Wang ◽  
Tianxiao Zhang ◽  
Zengping Lin ◽  
Yudu Li ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
High Resolution ◽  
Acute Stroke ◽  
Spatial Resolution ◽  
Tissue Level ◽  
Metabolic Imaging ◽  
Acquisition Time ◽  
Resonance Spectroscopy ◽  
Ischaemic Injury ◽  
Whole Brain

Abstract Impaired oxygen and cellular metabolism is a hallmark of ischaemic injury in acute stroke. Magnetic resonance spectroscopic imaging (MRSI) has long been recognized as a potentially powerful tool for non-invasive metabolic imaging. Nonetheless, long acquisition time, poor spatial resolution, and narrow coverage have limited its clinical application. Here we investigated the feasibility and potential clinical utility of rapid, high spatial resolution, near whole-brain 3D metabolic imaging based on a novel MRSI technology. In an 8-min scan, we simultaneously obtained 3D maps of N-acetylaspartate and lactate at a nominal spatial resolution of 2.0 × 3.0 × 3.0 mm3 with near whole-brain coverage from a cohort of 18 patients with acute ischaemic stroke. Serial structural and perfusion MRI was used to define detailed spatial maps of tissue-level outcomes against which high-resolution metabolic changes were evaluated. Within hypoperfused tissue, the lactate signal was higher in areas that ultimately infarcted compared with those that recovered (P < 0.0001). Both lactate (P < 0.0001) and N-acetylaspartate (P < 0.001) differed between infarcted and other regions. Within the areas of diffusion-weighted abnormality, lactate was lower where recovery was observed compared with elsewhere (P < 0.001). This feasibility study supports further investigation of fast high-resolution MRSI in acute stroke.

High‐resolution magnetic resonance imaging of trabecular bone in the wrist at 3 tesla: initial results

2005 ◽  
Vol 46 (3) ◽  
pp. 306-309 ◽  
Author(s):  
B. Ludescher ◽  
P. Martirosian ◽  
S. Lenk ◽  
J. Machann ◽  
F. Dammann ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Trabecular Bone ◽  
Spatial Resolution ◽  
Bone Structure ◽  
3 Tesla ◽  
Spongy Bone ◽  
Resonance Imaging ◽  
High Resolution Mri

Purpose: To evaluate the feasibility of high‐resolution magnetic resonance imaging (MRI) of trabecular bone of the wrist at 3 Tesla (3T) in vivo and to assess the potential benefit of the increased resolution for clinical assessment of structural changes in spongy bone. Material and Methods: High‐resolution MRI of the wrist was performed with a whole‐body 3T MR scanner using a dedicated circularly polarized transmit–receive wrist‐coil. Two 3D‐FISP sequences with a spatial resolution of 300×300×300 µm3 in a measuring time of TA = 7:51 min, and 200×200×200 µm3 in TA = 9:33 min were applied. Seven young healthy volunteers and three elderly subjects with suspected osteoporosis were examined. The signal‐to‐noise ratio (SNR) in the optimized setup at 3T was compared to measurements at 1.5T. Results: The images at 3T allow microscopic analysis of the bone structure at an isotropic spatial resolution of 200 µm in examination times of <10 min. Differences in the structure of the spongy bone between normal and markedly osteoporotic subjects are well depicted. The SNR at 3T was found up to 16 times higher than at 1.5T applying unchanged imaging parameters. Conclusion: The proposed high‐resolution MRI technique offers high potential in the diagnosis and follow‐up of diseases with impaired bone structure of hand and/or wrist in clinical applications.

scholarly journals Medullary vein architecture modulates the white matter BOLD cerebrovascular reactivity signal response to CO2: observations from high-resolution T2* weighted imaging at 7T

2021 ◽  
Author(s):  
Alex A. Bhogal
Keyword(s):  
White Matter ◽  
High Resolution ◽  
Vascular Reactivity ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
7 Tesla ◽  
Hemodynamic Parameters ◽  
Vascular Control ◽  
Bold Imaging ◽  
Anatomical Images

ABSTRACTBrain stress testing using blood oxygenation level-dependent (BOLD) MRI to evaluate changes in cerebrovascular reactivity (CVR) is of growing interest for evaluating white matter integrity. However, even under healthy conditions, the white matter BOLD-CVR response differs notably from that observed in the gray matter. In addition to actual arterial vascular control, the venous draining topology may influence the WM-CVR response leading to signal delays and dispersions. These types of alterations in hemodynamic parameters are sometimes linked with pathology, but may also arise from differences in normal venous architecture. In this work, high-resolution T2*weighted anatomical images combined with BOLD imaging during a hypercapnic breathing protocol were acquired using a 7 tesla MRI system. Hemodynamic parameters including base CVR, hemodynamic lag, lag-corrected CVR, response onset and signal dispersion, and finally ΔCVR (corrected CVR minus base CVR) were calculated in 8 subjects. Parameter maps were spatially normalized and correlated against an MNI-registered white matter medullary vein atlas. Moderate correlations (Pearson’s rho) were observed between medullary vessel frequency (MVF) and ΔCVR (0.52; 0.58 for total WM), MVF and hemodynamic lag (0.42; 0.54 for total WM), MVF and signal dispersion (0.44; 0.53 for total WM), and finally MVF and signal onset (0.43; 0.52 for total WM). Results indicate that, when assessed in the context of the WM venous architecture, changes in the response shape may only be partially reflective of the actual vascular reactivity response occurring further upstream by control vessels. This finding may have implications when attributing diseases mechanisms and/or progression to presumed impaired WM BOLD-CVR.

PD54-08 EX-VIVO EXPERIMENTAL 7 TESLA HIGH RESOLUTION MAGNETIC RESONANCE IMAGING - OF LOCALIZED PROSTATE CANCER

2020 ◽  
Vol 203 ◽  
pp. e1106-e1107
Author(s):  
Matthieu Durand* ◽  
Thomas Bessede ◽  
Patrick-Julien Treacy ◽  
Imad Bentellis ◽  
Idoia Corcuera-Solano ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Prostate Cancer ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Ex Vivo ◽  
Localized Prostate Cancer ◽  
7 Tesla ◽  
Resonance Imaging

scholarly journals Effect of Filtered Back-Projection Filters to Low-Contrast Object Imaging in Ultra-High-Resolution (UHR) Cone-Beam Computed Tomography (CBCT)

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6416
Author(s):  
Sunghoon Choi ◽  
Chang-Woo Seo ◽  
Bo Kyung Cha
Keyword(s):  
Computed Tomography ◽  
High Resolution ◽  
Spatial Frequency ◽  
Spatial Resolution ◽  
Cone Beam Computed Tomography ◽  
Cone Beam ◽  
Acquisition Time ◽  
Imaging Protocol ◽  
Low Contrast ◽  
Smoothing Window

In this study, the effect of filter schemes on several low-contrast materials was compared using standard and ultra-high-resolution (UHR) cone-beam computed tomography (CBCT) imaging. The performance of the UHR-CBCT was quantified by measuring the modulation transfer function (MTF) and the noise power spectrum (NPS). The MTF was measured at the radial location around the cylindrical phantom, whereas the NPS was measured in the eight different homogeneous regions of interest. Six different filter schemes were designed and implemented in the CT sinogram from each imaging configuration. The experimental results indicated that the filter with smaller smoothing window preserved the MTF up to the highest spatial frequency, but larger NPS. In addition, the UHR imaging protocol provided 1.77 times better spatial resolution than the standard acquisition by comparing the specific spatial frequency (f50) under the same conditions. The f50s with the flat-top window in UHR mode was 1.86, 0.94, 2.52, 2.05, and 1.86 lp/mm for Polyethylene (Material 1, M1), Polystyrene (M2), Nylon (M3), Acrylic (M4), and Polycarbonate (M5), respectively. The smoothing window in the UHR protocol showed a clearer performance in the MTF according to the low-contrast objects, showing agreement with the relative contrast of materials in order of M3, M4, M1, M5, and M2. In conclusion, although the UHR-CBCT showed the disadvantages of acquisition time and radiation dose, it could provide greater spatial resolution with smaller noise property compared to standard imaging; moreover, the optimal window function should be considered in advance for the best UHR performance.

Another Piece of the Puzzle of Anomalous Connectivity in Joubert's Syndrome

2021 ◽  
Author(s):  
Avner Meoded ◽  
Marcia Kukreja ◽  
Gunes Orman ◽  
Eugen Boltshauser ◽  
Thierry A.G.M. Huisman
Keyword(s):  
White Matter ◽  
Diffusion Tensor ◽  
Three Dimensional ◽  
Axonal Guidance ◽  
Molar Tooth ◽  
Superior Cerebellar Peduncle ◽  
Corticospinal Tracts ◽  
Cerebellar Peduncles ◽  
Cerebellar Peduncle ◽  
Magnetic Resonance Imaging Mri

AbstractWe report on the conventional and diffusion tensor imaging (DTI) findings of a 2-year-old child with clinical presentation of Joubert's Syndrome (JS) and brainstem structural abnormalities as depicted by neuroimaging.Conventional magnetic resonance imaging (MRI) showed a “molar tooth” configuration of the brainstem. A band-like formation coursing in an apparent axial plane anterior to the interpeduncular fossa was noted and appeared to partially cover the interpeduncular fossa.DTI maps and three-dimensional (3D) tractography demonstrated a prominent red-encoded white matter bundle anterior to the midbrain. Probable aberrant course of the bilateral corticospinal tracts (CST) was also depicted. Absence of the decussation of the superior cerebellar peduncles and elongated thickened, horizontal superior cerebellar peduncle (SCP) reflecting the molar tooth sign were also shown.Our report and the review of the published cases suggest that DTI and tractography may be very helpful to differentiate between interpeduncular heterotopias and similarly located white matter bundles corroborating the underlying etiology of axonal guidance disorders in the complex group of ciliopathies including JS. Our case represents an important additional puzzle piece to explore the variability of these ciliopathies.

Sign in / Sign up

Export Citation Format

Share Document