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World J Radiol. Jul 28, 2014; 6(7): 409-416
Published online Jul 28, 2014. doi: 10.4329/wjr.v6.i7.409
Clinical significance of visceral adiposity assessed by computed tomography: A Japanese perspective
Miwa Ryo, Ken Kishida, Tadashi Nakamura, Tohru Yoshizumi, Tohru Funahashi, Iichiro Shimomura
Miwa Ryo, Ken Kishida, Tadashi Nakamura, Tohru Yoshizumi, Tohru Funahashi, Iichiro Shimomura, Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
Miwa Ryo, Osaka Health Support Center, Sumitomo Mitsui Banking Corporation, Osaka 541-0041, Japan
Ken Kishida, Department of Hemodialysis, Kishida Clinic, Toyonaka, Osaka 560-0021, Japan
Tadashi Nakamura, Department of Internal Medicine, Kawasaki Hospital, Kobe, Hyogo 652-0042, Japan
Tohru Yoshizumi, Department of Radiology, Kawasaki Hospital, Kobe, Hyogo 652-0042, Japan
Tohru Funahashi, Department of Metabolism and Atherosclerosis, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
Author contributions: Ryo M, Kishida K, Nakamura T, Yoshizumi T, Funahashi T and Shimomura I contributed to this work.
Correspondence to: Miwa Ryo, MD, PhD, Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, 2-2 B-5, Yamada-oka, Suita, Osaka 565-0871, Japan. ryomw@gaia.eonet.ne.jp
Telephone: +81-6-68793732 Fax: +81-6-68793739
Received: December 27, 2013
Revised: February 11, 2014
Accepted: April 25, 2014
Published online: July 28, 2014
Abstract

Abdominal obesity, rather than total amount of fat, is linked to obesity-related disorders. Visceral adiposity is an important component of obesity-related disorders in Japanese individuals with a mild degree of adiposity compared with Western subjects. In 1983, our group reported techniques for body fat analysis using computed tomography (CT) and established the concept of visceral fat obesity in which intra-abdominal fat accumulation is an important factor in the development of obesity-related complications, such as diabetes, lipid disorders, hypertension and atherosclerosis. Our group also established ideal imaging conditions for determining abdominal fat area at the umbilical level CT scan. Visceral fat area (VFA) measured in a single slice at L4 level correlated significantly with the total abdominal visceral fat volume measured on multislice CT scan. In a large-scale study of a Japanese population, the mean number of obesity-related cardiovascular risk factors (hypertension, low high-density lipoprotein cholesterolemia and/or hypertriglyceridemia, and hyperglycemia) was greater than 1.0 at 100 cm2 of VFA, irrespective of gender, age and body mass index. Our group also demonstrated that reduction of visceral fat accumulation subsequent to voluntary lifestyle modification, “Hokenshido”, correlated with a decrease in the number of obesity-related cardiovascular risk factors. It is important to select the most appropriate subjects from the general population (e.g., non-obese subjects with a cluster of risk factors for the metabolic syndrome) that are most suitable for body weight reduction, with the goal of preventing atherosclerotic cardiovascular diseases.

Keywords: Visceral fat, Metabolic syndrome, Computed tomography, Atherosclerotic cardiovascular diseases

Core tip: Accumulation of intra-abdominal visceral fat correlates with atherogenic and metabolic abnormalities, collectively known as the metabolic syndrome. Visceral adiposity is an important component of the syndrome in Japanese individuals with mild adiposity compared with Western subjects. A computed tomography (CT) scan allows the separate analysis of subcutaneous fat and visceral fat, and the visceral fat area (VFA) from a single CT slice L4 level correlates with total visceral fat volume. A VFA cut-off value of 100 cm2 is used for risk assessment of obesity-related disorders.