Diffusion-weighted imaging features of brain in obesity.

PURPOSE Obesity is characterized by an altered distribution of body fluid. However, distribution of fluid (extracellular/intracellular) in brain tissues has not been studied in obese subjects yet. The purpose of this study was to detect possible brain diffusion changes especially in satiety and hunger related centers in obese subjects by diffusion weighted imaging (DWI). METHODS Conventional MRI and DWI of the brain was obtained from 81 obese patients (obese=68, morbid obese=13) and 29 age-matched, nonobese. The apparent diffusion coefficient (ADC) values were calculated in hypothalamus; amygdala; hippocampal gyrus; thalamus; insula; cingulate gyrus; orbitofrontal, dorsomedial and dorsolateral frontal, middle temporal and occipital cortex; cerebellum; midbrain and corpus striatum. RESULTS The ADC values of hypothalamus, hippocampal gyrus, amygdala, insula, cerebellum and midbrain were significantly increased in patients (n:81) when compared to nonobese subjects. The ADC values of thalamus, hippocampal gyrus, amygdala, orbitofrontal, occipital, dorsolateral and middle temporal cortex, insula and midbrain were significantly increased in morbid obese when compared to nonobese subjects. The ADC values of orbitofrontal and occipital cortex were significantly higher in morbid obese than the values in the obese. The body mass index positively correlated with ADC values of amygdala, insula, orbitofrontal and middle temporal cortex. CONCLUSION We observed increased ADC values of distinct locations related to satiety and hunger that suggest altered fluid distribution and/or vasogenic edema in obese subjects. Awareness of this abnormalities in brain tissue composition/function in obesity may contribute to better understanding of the underlying mechanisms.

[1]  E. Ravussin,et al.  Neuroanatomical correlates of hunger and satiation in humans using positron emission tomography. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[2]  Neuroimaging and obesity. , 2001, Obesity research.

[3]  Laura M. Holsen,et al.  Neural mechanisms underlying food motivation in children and adolescents , 2005, NeuroImage.

[4]  Sterling C. Johnson,et al.  The effect of body mass index on global brain volume in middle-aged adults: a cross sectional study , 2005, BMC neurology.

[5]  E M Reiman,et al.  Effect of satiation on brain activity in obese and lean women. , 2001, Obesity research.

[6]  J. Parkinson,et al.  Neural contributions to the motivational control of appetite in humans , 2004, The European journal of neuroscience.

[7]  Nicola Pannacciulli,et al.  In pursuit of neural risk factors for weight gain in humans , 2005, Neurobiology of Aging.

[8]  M. Fogelholm,et al.  Increased extracellular water compartment, relative to intracellular water compartment, after weight reduction. , 1999, Journal of applied physiology.

[9]  I. Loubinoux,et al.  Spreading of vasogenic edema and cytotoxic edema assessed by quantitative diffusion and T2 magnetic resonance imaging. , 1997, Stroke.

[10]  J. Friedman,et al.  Obesity in the new millennium , 2000, Nature.

[11]  A. Rabinstein,et al.  Diffusion-weighted imaging shows cytotoxic and vasogenic edema in eclampsia. , 2001, AJNR. American journal of neuroradiology.

[12]  B. Popkin,et al.  The altered fluid distribution in obesity may reflect plasma hypertonicity , 2007, European Journal of Clinical Nutrition.

[13]  P. Tataranni,et al.  Functional neuroimaging: a new generation of human brain studies in obesity research , 2003, Obesity reviews : an official journal of the International Association for the Study of Obesity.

[14]  G. Barsh,et al.  Genetic approaches to studying energy balance: perception and integration , 2002, Nature Reviews Genetics.

[15]  Nicole L. Nollen,et al.  Neural Mechanisms Underlying Hyperphagia in Prader‐Willi Syndrome , 2006, Obesity.

[16]  D. Shibata,et al.  Diffusion-weighted echo-planar MR imaging: clinical applications and pitfalls -- a pictorial essay. , 2000, Clinical imaging.