Noninvasive Assessment of Advanced Fibrosis Based on Hepatic Volume in Patients with Nonalcoholic Fatty Liver Disease

BACKGROUND/AIMS: Noninvasive liver fibrosis evaluation was performed in patients with nonalcoholic fatty liver disease (NAFLD). We used a quantitative method based on the hepatic volume acquired from gadoxetate disodium-enhanced (Gd-EOB-DTPA-enhanced) magnetic resonance imaging (MRI) for diagnosing advanced fibrosis in patients with NAFLD. METHODS: A total of 130 patients who were diagnosed with NAFLD and underwent Gd-EOB-DTPA-enhanced MRI were retrospectively included. Histological data were available for 118 patients. Hepatic volumetric parameters, including the left hepatic lobe to right hepatic lobe volume ratio (L/R ratio), were measured. The usefulness of the L/R ratio for diagnosing fibrosis ≥F3–4 and F4 was assessed using the area under the receiver operating characteristic (AUROC) curve. Multiple regression analysis was performed to identify variables (age, body mass index, serum fibrosis markers, and histological features) that were associated with the L/R ratio. RESULTS: The L/R ratio demonstrated good performance in differentiating advanced fibrosis (AUROC, 0.80; 95% confidence interval, 0.72 to 0.88) from cirrhosis (AUROC, 0.87; 95% confidence interval, 0.75 to 0.99). Multiple regression analysis showed that only fibrosis was significantly associated with the L/R ratio (coefficient, 0.121; p<0.0001). CONCLUSIONS: The L/R ratio, which is not influenced by pathological parameters other than fibrosis, is useful for diagnosing cirrhosis in patients with NAFLD.

DETERMINATION OF OPTIMAL EXERCISE INTENSITY BASED ON REAL-TIME ANALYSIS OF HEART RATE VARIABILITY DURING EXERCISE / 体力科学

The purpose of the present study was to develop a new method that enables individualized determination of the optimal exercise intensity for health promotion. Our study was based on the following observations : (1) physical activity at ventilatory threshold (VT) has been useful for enhancing physical fitness and even improving medical conditions such as heart failure, hypertension and diabetes, (2) exercise intensity at VT is characterized by suppressed vagal activity, and (3) vagal activity can be evaluated by analyzing heart rate variability (HRV) . In the first study we defined a criteria for determining the exercise intensity corresponding to VT using HRV analysis (heart rate variability threshold, THRV) . In 16 normal subjects, a time series of ECG RR interval were recorded and the means of the sum of the squared differences in successive RR intervals (MSSDs) were calcu-lated during a ramp exercise test with a cycle ergometer. Based on the values of MSSD and the dif-ferences in successive MSSDs (ΔMSSD) at the intensity of VT, we defined the criteria of THRV as follows : MSSD<25 msec<SUP>2</SUP>and ΔMSSD<6 msec<SUP>2</SUP>. Another exercise test with a cycle ergo-meter was performed to evaluate the relationship between THRV and VT in 63 normal subjects. Heart rate (HR) and oxygen uptake (VO<SUB>2</SUB>/wt) at THRV were 111.8±13.2 beats/min and 15.2±4.4 ml/kg/min, and HR and VO<SUB>2</SUB>/wt at VT were 116.2±11.6beats/min and 16.5±3.7ml/kg/min, respectively. There was a significant correlation between THRV and VT (HR : r=0.82, p<0.001, VO<SUB>2</SUB>/wt : r=0.88, p< 0.001) . Thus, THRV and VT provided almost identical exercise intensities. As a result, we propose that, similar to VT, THRV can be used as an indicator of the optimal exercise intensity suitable for health promotion in normal subjects.

MOVEMENT OF ELECTOROENCEPHALOGRAM AND PLASM β-ENDORPHIN IN THE AEROBIC EXERCISE / 体力科学

The present study was designed to examine the effects of aerobic exercise on the change of alpha wave component in electroencephalogram (EEG) and plasma β-endorphin. Exercise consisted of 30-min cycling on an ergometer with the load adjusted to elicit a heart rate rise of 50% between resting and predicted maximal value. The EEG signals and blood samples were obtained before and after 30-min exercise. The EEG signal was digitized at a sampling frequency of 64 Hz and analyzed by means of computer-aided decomposition algorithm and frequency power spectral analyses, respectively. The blood samples were immediately centrifuged for 15-min for quantitative analysis of β-endorphin by means of radioimmunoassay method. Results indicated that β-endorphin was significatly (p<.05) greater after exercise as compared to that of the resting contorol. It was also found that the larger the changes in β-endorphin following exercise, the higher the appearance rate of alpha wave in EEG. There was a positive and significant correlation (r=563, p<0.05) between the increase in alpha wave component and that of the plasma β-endorphin. These results suggest that traquilizer effects of aerobic exercise could be explained, at least in part, by the increase of alpha wave component and plasma β-endorphin which in turn bring about the relaxation effects upon the central nervous system.

Movement of electroencephalogram and plasm .BETA.-endorphin in the aerobic exercise / 体力科学

The present study was designed to examine the effects of aerobic exercise on the change of alpha wave component in electroencephalogram (EEG) and plasma β-endorphin. Exercise consisted of 30-min cycling on an ergometer with the load adjusted to elicit a heart rate rise of 50% between resting and predicted maximal value. The EEG signals and blood samples were obtained before and after 30-min exercise. The EEG signal was digitized at a sampling frequency of 64 Hz and analyzed by means of computer-aided decomposition algorithm and frequency power spectral analyses, respectively. The blood samples were immediately centrifuged for 15-min for quantitative analysis of β-endorphin by means of radioimmunoassay method. Results indicated that β-endorphin was significatly (p<.05) greater after exercise as compared to that of the resting contorol. It was also found that the larger the changes in β-endorphin following exercise, the higher the appearance rate of alpha wave in EEG. There was a positive and significant correlation (r=563, p<0.05) between the increase in alpha wave component and that of the plasma β-endorphin. These results suggest that traquilizer effects of aerobic exercise could be explained, at least in part, by the increase of alpha wave component and plasma β-endorphin which in turn bring about the relaxation effects upon the central nervous system.