Brain magnetic resonance imaging

Magnetic resonance imaging (MRI) of the head is a painless, noninvasive test that produces detailed images of your brain and brain stem. The test is carried out with an MRI machine, which produces the images using a magnetic field and radio waves. This test is also known as a brain MRI or a cranial MRI. The test will be carried out at a hospital or radiology center.

Differential diagnosis of brain magnetic resonance imaging (MRI) enhancement(s) remains a significant problem, which may be difficult to resolve without biopsy that can be often dangerous or even impossible. Such MRI enhancement(s) can result from metastases of primary tumors such as lung or breast, radiation necrosis, infections or a new primary brain tumor (glioma, meningioma). Neurological symptoms are often the same on initial presentation.

Specific anatomical patterns are seen in various diseases affecting the brain. Clinical studies on the topography of pathologies are often limited by the absence of a normalization of the prevalence of pathologies to the relative volume of the affected anatomical structures. A comprehensive reference on the relative volumes of clinically relevant anatomical structures serving for such normalization is currently lacking. The analyses are based on anatomical high-resolution three-dimensional T1-weighted magnetic resonance imaging data of 30 healthy Caucasian volunteers, including 14 females (mean age 37.79 years, SD 13.04) and 16 males (mean age 38.31 years, SD 16.91). Semi-automated anatomical segmentation was used, guided by a neuroanatomical parcellation algorithm differentiating 96 structures. Relative volumes were derived by normalizing parenchymal structures to the total individual encephalic volume and ventricular segments to the total individual ventricular volume. The present investigation provides the absolute and relative volumes of 96 anatomical parcellation units of the human encephalon. A larger absolute volume in males than in females is found for almost all parcellation units. While parenchymal structures display a trend towards decreasing volumes with increasing age, a significant inverse effect is seen with the ventricular system. The variances in volumes, as well as the effects of gender and age, are given for each structure before and after normalization. The provided atlas constitutes an anatomically detailed and comprehensive analysis of the absolute and relative volumes of the human encephalic structures using a clinically oriented parcellation algorithm. It is intended to serve as a reference for volume-standardization in clinical studies on the topographic prevalence of pathologies 1).

Magnetic resonance imaging studies typically use standard anatomical atlases for identification and analyses of (patho-)physiological effects on specific brain areas; these atlases often fail to incorporate neuroanatomical alterations that may occur with both age and disease. The present study utilizes Parkinson's disease and age-specific anatomical atlases of the subthalamic nucleus for diffusion tractography, assessing tracts that run between the subthalamic nucleus and a-priori defined cortical areas known to be affected by Parkinson's disease. The results show that the strength of white matter fiber tracts appear to remain structurally unaffected by disease. Contrary to that, Fractional Anisotropy values were shown to decrease in Parkinson's disease patients for connections between the subthalamic nucleus and the pars opercularis of the inferior frontal gyrus, anterior cingulate cortex, the dorsolateral prefrontal cortex and the pre-supplementary motor, collectively involved in preparatory motor control, decision making and task monitoring. While the biological underpinnings of fractional anisotropy alterations remain elusive, they may nonetheless be used as an index of Parkinson's disease. Moreover, we find that failing to account for structural changes occurring in the subthalamic nucleus with age and disease reduce the accuracy and influence the results of tractography, highlighting the importance of using appropriate atlases for tractography 2).

Ventricular shunt malfunction

Rapid cranial MRI was not inferior to CT for diagnosing ventricular shunt malfunction and offers the advantage of sparing a child ionizing radiation exposure 3).

Currently, most High-grade glioma patients undergo a 1.5 Tesla brain magnetic resonance (MR) for radiation treatment planning. We hypothesized that 3T MR imaging (MRI) scanning is superior to 1.5T due to higher signal-to-noise ratio (SNR), and thus will result in more accurate quantification of tumor volumes. The purpose of this prospective study was to determine differences in radiation planning volumes for high-grade gliomas when scanned on 3T MR versus 1.5T MR.

Akeret K, van Niftrik CHB, Sebök M, Muscas G, Visser T, Staartjes VE, Marinoni F, Serra C, Regli L, Krayenbühl N, Piccirelli M, Fierstra J. Topographic volume-standardization atlas of the human brain. Brain Struct Funct. 2021 May 7. doi: 10.1007/s00429-021-02280-1. Epub ahead of print. PMID: 33961092.
Isaacs BR, Trutti AC, Pelzer E, Tittgemeyer M, Temel Y, Forstmann BU, Keuken MC. Cortico-basal white matter alterations occurring in Parkinson's disease. PLoS One. 2019 Aug 19;14(8):e0214343. doi: 10.1371/journal.pone.0214343. eCollection 2019. PubMed PMID: 31425517.
Boyle TP, Paldino MJ, Kimia AA, Fitz BM, Madsen JR, Monuteaux MC, Nigrovic LE. Comparison of rapid cranial MRI to CT for ventricular shunt malfunction. Pediatrics. 2014 Jul;134(1):e47-54. doi: 10.1542/peds.2013-3739. Epub 2014 Jun 2. PubMed PMID: 24918222.
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