Brain changes detected by functional magnetic resonance imaging and spectroscopy in patients with Crohn's disease

Table 1 Studies of blood oxygenation level dependent functional magnetic resonance imaging and magnetic resonance spectroscopy in Crohn's disease

Ref.	Destination	Inspection	Location	Main metabolites	Results
Agostini et al[37], 2013	Habituation to stress in CD	BOLD-fMRI (Task-state)	Brain	NA	Different neural activities in the amygdala, hippocampus, insula, putamen and cerebellar between CD patients and controls
Bao et al[38], 2016	Brain activity in paracmastic CD patients	BOLD-fMRI (Resting-state)	Brain	NA	ReHo values: Abdominal pain: insula, MCC, SMA↑, temporal pole↓; Without abdominal pain: hoppocampal/parahippocampial cortex↑, dorsomedial prefrontal cortex↓
Bezabeh et al[41], 2001	Diagnosis in CD and UC	MRS	Colonic mucosal	Taurine, lysine, lipid, choline, creatine	The diagnostic spectral regions include taurine, lysine, and lipids
Varma et al[42], 2007	Early screening of IBD	MRS	Colonic mucosal	Creatinine and phosphatidylcholine	Triglycerides, creatine, phosphocholine and glycerol backbone of lipids are the most discriminatory metabolites
Fathi et al[43], 2014	Biomarkers of CD	MRS	Serum	Alanine, glutamine, leucine/isoleucine, lysine and valine	Two chemical shifts of isoleucine (0.99 ppm) and valine (1.03 ppm) have considerable impact for discriminating patient and normal samples

BOLD-fMRI: Blood oxygenation level dependent functional magnetic resonance imaging; CD: Crohn's disease; IBD: Inflammatory bowel disease; MCC: Middle cingulate cortex; MRS: Magnetic resonance spectroscopy; NA: Not available; ReHo: Regional homogeneity; SMA: Supplementary motor area; UC: Ulcerative colitis.

Table 2 Metabolites for magnetic resonance spectroscopy and their functions in normal adult human brain[66]

Metabolite	Chemical shift (ppm)	Concentration range (mmol/kgww)	Functions
NAA	2.02	7.9-16.6 (average 10.3)	An osmolite, a storage form of aspartate, a precursor of NAAG, a marker of neuronal density
GABA	3.01	1.3-1.9	A primary inhibitory neurotransmitter
tCho	3.20	0.9-2.5	An essential nutrient that is required for synthesis of the neurotransmitter acetylcholine, and of phosphatidylcholine, a major constituent of membranes
Cr	3.05	5.1-10.6	A concentration reference
Glu	2.04-2.35	6.0-12.5	An excitatory neurotransmitter
Gln	2.12-2.46	3.0-5.8	A precursor and storage form of glutamate
mI	3.56	3.8-8.1	An essential requirement for cell growth, and a storage form for glucose
Lac	1.33-1.35	0.4	The end product of anaerobic glycolysis

Cr: Creatine; GABA: γ-aminobutyric acid; Glu: Glutamate; Gln: Glutamine; Lac: Lactate; mI: Myo-inositol; mmol/kgww: mmol/kg of wet weight; NAA: N-acetylaspartate; ppm: Parts per million; tCho: Choline (total), free choline, glycerophosphorylcholine, and phosphorylcholine.