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Developmental Diseases of the Nervous System
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
James H. Tonsgard, Nikolas Mata-Machado
MRI with enhancement demonstrates the vascular malformation. This can usually be seen within the first year of life, but may not be easily visible initially. Fluid-attenuated inversion recovery (FLAIR) sequences in the MRI, as well as MR venography, may be useful. CT demonstrates calcification of the underlying cortex relatively early, usually within the first 2 years of life.
Anterior thalamic nucleus stimulation: surgical procedure
Published in Hans O Lüders, Deep Brain Stimulation and Epilepsy, 2020
Magnetic resonance imaging (MRI) is performed for targeting with a 1.5 tesla MRI unit (Signa, General Electric). Target anatomy is best seen in the fast-spin echo inversion recovery, and standard T-2 weighted sequences. At first, sagittal images are obtained to define the AC-PC line. Axial images parallel to the AC-PC line and coronal images perpendicular to the AC-PC plane are then obtained. We usually determine the stereotactic coordinate of the target point by three methods as follows.
Biomedical Imaging Magnetic Resonance Imaging
Published in Lawrence S. Chan, William C. Tang, Engineering-Medicine, 2019
Free water has a very long T2 value (~ 2 s at 1.5 T), making CSF appear hyperintense in a T2-weighted image (Fig. 14c). The intense CSF signals can sometimes mask T2-weighted contrast between other tissues. An effective way to solve this problem is to apply an inversion pulse and wait until the inverted CSF signal to be at the null point (Fig. 7) before executing an FSE pulse sequence. Because CSF has a substantially longer T1 (~ 4 s at 1.5 T) than the other brain tissues, when the CSF signal reaches the null point, the magnetization for other brain tissues is almost fully recovered, resulting in a T2-weighted image with the CSF signal suppressed (Fig. 14d). This technique is known as fluid attenuated inversion recovery (FLAIR) (Hajnal et al. 1992).
White matter lesions are associated with obstructive sleep apnea hypopnea syndrome
Published in Neurological Research, 2022
Weihua Huang, Huanmin Li, Huan Li, Tianrong Huang, Shiqi Yuan, Tianming Lü
MRI was performed following a standard protocol including T1 and T2 weighted and fluid attenuated inversion recovery sequences using a 1.5 T or 3.0 T magnet (Philips Medical Systems Greater China). On magnetic resonance imaging (MRI), WML are seen as hyperintensities on fluid-attenuated inversion recovery sequences (FLAIR). FLAIR is now the preferred imaging modality to assess the presence and severity of WMLs. The degree of WML was rated on FLAIR by two trained investigators who were blind to the clinical data. The Fazekas scale was used to measure the white matter hypertensities [12]. Disagreements in imaging analysis were resolved by consensus. Considering only deep and subcortical white matter, WML was defined for single lesions that must be more than 3 mm or more in any diameter. The mild and moderate-or-severe levels of white matter changes were combined to define white matter abnormality, which was then compared to those without white matter changes.
Cortical projection neurons as a therapeutic target in multiple sclerosis
Published in Expert Opinion on Therapeutic Targets, 2020
Tatjana Beutel, Julia Dzimiera, Hannah Kapell, Maren Engelhardt, Achim Gass, Lucas Schirmer
MRI is the prime method when it comes to monitoring progressive pathological changes in subcortical WM and cortical GM areas in MS patients. The current standard in MS imaging is the use of 1.5T and 3T MRI systems. Hyperintense lesions on T2-weighted MRI including FLAIR and contrast-enhancing lesions on post-contrast T1-weighted MRI are the main diagnostic tools to study inflammatory disease activity [44,45]. The visualization of cortical lesions and/or cortical thinning is more challenging as most cortical lesions are small and show relatively less inflammation-driven edema and demyelination. Compared to WM lesions this leads to a less pronounced T2 prolongation time [46–48]. Hence, double inversion recovery sequences provide a higher contrast between lesioned and healthy tissue, which has assisted in the study of cortical lesions at 1.5 and 3T [46,49,50].
Comparison between high-resolution 3D-IR with real reconstruction and 3D-flair sequences in the assessment of endolymphatic hydrops in 3 tesla
Published in Acta Oto-Laryngologica, 2020
Víctor Manuel Suárez Vega, Pablo Dominguez, Fanny Meylin Caballeros Lam, Jose Ignacio Leal, Nicolás Perez-Fernandez
It was Nakashima et al. [9] who first described in vivo assessment of endolymphatic hydrops using high definition 3D fluid-attenuated inversion recovery (FLAIR) sequences in a 3 Tesla scan after the intra-timpanic administration of contrast agent gadolinium (Gd). Later on, they demonstrated that another sequence named 3D inversion-recovery (3D-IR) turbo spin echo with real reconstruction showed higher contrast between the non-enhanced endolymph and the surrounding bone, thanks to a shorter inversion time than the FLAIR sequence [10]. Although intratympanic route of Gd administration has been widely used, the intravenous administration in single or double dose is also feasible and has the advantage of being able to evaluate both ears at the same time [11,12] and allowing for an easy correlation to frequently used audiological and vestibular tests to characterize the disease in a given patient [13].