Studying magnetic susceptibility, microstructural compartmentalisation and chemical exchange in a formalin-fixed ex vivo human brain specimen

Purpose: Ex vivo imaging is a preferable method to study the biophysical mechanism of white matter orientation-dependent signal phase evolution. Yet, how formalin fixation, commonly used for tissue preservation, affects the phase measurement is not fully known. We, therefore, study the impacts of formalin fixation on magnetic susceptibility, microstructural compartmentalisation and chemical exchange measurement on human brain tissue. Methods: A formalin-fixed, post-mortem human brain specimen was scanned with multiple orientations with respect to the main magnetic field direction for robust bulk magnetic susceptibility measurement with conventional quantitative susceptibility imaging models. Homogeneous white matter tissues were subsequently excised from the whole-brain specimen and scanned in multiple rotations on an MRI scanner to measure the anisotropic magnetic susceptibility and microstructure-related contributions in the signal phase. Electron microscopy was used to validate the MRI findings. Results: The bulk isotropic magnetic susceptibility of ex vivo whole-brain imaging is comparable to in vivo imaging, with noticeable enhanced non-susceptibility contributions. The excised specimen experiment reveals that anisotropic magnetic susceptibility and compartmentalisation phase effect were considerably reduced in formalin-fixed white matter tissue. Conclusions: Despite formalin-fixed white matter tissue has comparable bulk isotropic magnetic susceptibility to those measured via in vivo imaging, its orientation-dependent components in the signal phase related to the tissue microstructure is substantially weaker, making it less favourable in white matter microstructure studies using phase imaging.

7 Tesla MRI of the ex vivo human brain at 100 micron resolution

We present an ultra-high resolution MRI dataset of an ex vivo human brain specimen. The brain specimen was donated by a 58-year-old woman who had no history of neurological disease and died of non-neurological causes. After fixation in 10% formalin, the specimen was imaged on a 7 Tesla MRI scanner at 100 µm isotropic resolution using a custom-built 31-channel receive array coil. Single-echo multi-flip Fast Low-Angle SHot (FLASH) data were acquired over 100 hours of scan time (25 hours per flip angle), allowing derivation of synthesized FLASH volumes. This dataset provides an unprecedented view of the three-dimensional neuroanatomy of the human brain. To optimize the utility of this resource, we warped the dataset into standard stereotactic space. We now distribute the dataset in both native space and stereotactic space to the academic community via multiple platforms. We envision that this dataset will have a broad range of investigational, educational, and clinical applications that will advance understanding of human brain anatomy in health and disease.

Atypical radiological presentation of multiple cystic brain metastases from lung cancer simulating neurocysticercosis

Brain metastases (BMs) are usually characterised by vasogenic oedema and mass effect, but cystic appearance can rarely occur, mimicking parasitosis, such as neurocysticercosis (NCC). A woman in her mid-50s was admitted for dizziness and upper left extremity paresis. Neuroimaging showed multiple cystic lesions consistent with multiple stages of NCC evolution, and empiric albendazole was started, without any clinical improvement. A whole-body CT revealed a pulmonary lesion in the right superior lobe. Pathological analysis from brain specimen demonstrated a clear cell lung carcinoma. The patient gradually worsened and died 4 months after the diagnosis. In conclusion, multiple cystic BMs are an atypical presentation on neuroimaging; in these cases, a meticulous diagnostic workup should be performed, looking for the possible site of malignancy. Even when it is not possible to perform a biopsy from the primitive lesion, as reported in this case, a brain biopsy should be considered.

7 Tesla MRI of the ex vivo human brain at 100 micron resolution

We present an ultra-high resolution MRI dataset of an ex vivo human brain specimen. The brain specimen was donated by a 58-year-old woman who had no history of neurological disease and died of non-neurological causes. After fixation in 10% formalin, the specimen was imaged on a 7 Tesla MRI scanner at 100 μm isotropic resolution using a custom-built 31-channel receive array coil. Single-echo multi-flip Fast Low-Angle SHot (FLASH) data were acquired over 100 hours of scan time (25 hours per flip angle), allowing derivation of a T1 parameter map and synthesized FLASH volumes. This dataset provides an unprecedented view of the three-dimensional neuroanatomy of the human brain. To optimize the utility of this resource, we warped the dataset into standard stereotactic space. We now distribute the dataset in both native space and stereotactic space to the academic community via multiple platforms. We envision that this dataset will have a broad range of investigational, educational, and clinical applications that will advance understanding of human brain anatomy in health and disease.

Osler vindicated: glioma of the leg center with Jacksonian epilepsy; removal and cure, with a 50-year follow-up

On December 14, 1883, William Osler, then pathologist at the Montreal General Hospital, presented the specimen of a brain with an almond-sized glioma beneath the right motor cortex to the Montreal Medico-Chirurgical Society. The brain specimen was from a young woman who had suffered from intermittent Jacksonian seizures for 14 years and had eventually died in status epilepticus. Aware of the pioneering removal of a tumor from the cortex reported on in 1885 by Bennett and Godlee, Osler wrote of his case, “this was an instance in which operation would have been justifiable and possibly have been the means of saving life.” In 1953, a young man with Jacksonian attacks that began in his foot underwent removal of a Grade I glioma from the central fissure. The operation was performed in an awake craniotomy during which cortical mapping was used to define the motor and sensory cortices. Treatment with focal radiation followed, and afterward the patient became seizure-free, stopped taking anticonvulsant medication, and has led an active life over the past 50 years. Reference is made to the experiences of Sherrington, Cushing, and Penfield with cortical stimulation in the awake patient under regional anesthesia as an effective aid to surgery for epileptogenic lesions, tumors, and vascular malformations. Their technique allows for maximal resection with minimal neurological deficits. Over the past 20 years, this approach has been adopted effectively in many neurosurgical centers.

Brain-cutting device for correlation of brain scan and autopsy sections

✓ The authors describe a frame with guides to facilitate accurate correlation of the planes of brain-specimen sections with computerized axial tomography brain scans.