Cerebral blood flow and fMRI BOLD auditory language activation in temporal lobe epilepsy

Abstract

Purpose BOLD fMRI, an important research and clinical tool, depends on relatively greater transient increases in (cerebral blood flow) rCBF than CMRO2 during neural activity. We investigated whether reduced resting rCBF in patients with TLE affects BOLD signal during fMRI language mapping. Methods We used [15O] water PET to measure rCBF, and 3T EPI BOLD fMRI with an auditory description decision task in 33 patients with temporal lobe epilepsy (16 men; age 33.6±10.6 years; epilepsy onset 14.8±10.6 years; mean duration 18.8±13.2 years; 23 left focus, 10 right focus). Anatomical regions drawn on structural MRI, based on the Wake Forest PickAtlas, included Wernicke’s area (WA), inferior frontal gyrus (IFG), middle frontal gyrus (MFG), and hippocampus (HC)]. Laterality indices (LI), and Asymmetry Indices (AI), were calculated on co-registered fMRI and PET. Key findings Twelve patients had mesial temporal sclerosis (7 left), two a tumor or malformation of cortical development (both left), one a right temporal cyst and 18 normal MRI (14 left). Decreasing relative left WA CBF correlated with decreased left IFG voxel activation and decreasing left IFG LI. However, CBF WA AI was not related to left WA voxel activation itself or WA LI. There was a weak positive correlation between absolute CBF and fMRI activation in left IFG, right IFG, and left WA. Patients with normal and abnormal MRI did not differ in fMRI activation or rCBF AI. Significance Reduced WA rCBF is associated with reduced fMRI activation in IFG but not WA itself, suggesting distributed network effects, but not impairment of underlying BOLD response. Hypoperfusion in TLE does not affect fMRI clinical value.

Spatially adaptive unsupervised multispectral nonlocal filtering for improved cerebral blood flow mapping using arterial spin labeling magnetic resonance imaging

“…Regional alterations in CBF have been found to be associated with brain development (Hagstadius and Risberg, 1989; Martin et al, 1991; Takahashi et al, 2005) and several central nervous system diseases, including dementia (Chao et al, 2010; Schuff et al, 2009), mild cognitive impairment (Luckhaus et al, 2008; Park et al, 2012), multiple sclerosis (Marshall et al, 2016; Ota et al, 2013), schizophrenia (Ota et al, 2014; Ragland et al, 2001), depression (Colloby et al, 2012; Wang et al, 2014), epilepsy (Appel et al, 2012; Touchon et al, 1986), and others (Alsop et al, 2000; Devet al, 2015; Du et al, 2006; Melzer et al, 2011). However, high-quality, HR MR imaging of CBF is challenging, especially in a clinical setting.…”

Mapping of cognitive functions in chronic intractable epilepsy: Role of fMRI

“…It suggests the processing of neurons in IFG and STG were not precisely interlinked at cellular level due to dysfunction of seizure mechanism in presurgical session which is in agreement with previous functional neuroimaging studies. [ 23 24 25 26 ] BOLD activation in MTG and STG is involved in integration of semantic and syntactic information and is particularly responsive to meaningful sentences during semantic reading task. [ 27 28 22 ] Patients with left hippocampal sclerosis usually showed atypical language lateralization, which may suggest hippocampal involvement in semantic and lexical information during targeted word retrieval.…”

The effects of cerebral white matter changes on cardiovascular responses to cognitive and physical activity in a stroke population

“…The Wake Forest Pick Atlas (Maldjian, Laurienti, Kraft, & Burdette, ) is a tool for creating ROI masks using normalized brain template regions. The atlas has been successfully used in a diverse range of ROI studies (e.g., Appel et al., ; Woolley et al., ). These masks were then applied to each image using an automated MatLab v. 7.9 (MathWorks, Natick, MA) script to generate the regional FA values.…”