Table 2. Validation and reliability of main parameters of adiposity assessed by ultrasound.
| Parameter | Reference | Validation and reliability |
|---|---|---|
| IAFT | (14,27-32) | Good correlation with CT- and MRI-derived areas and volumes. Very good correlation with CT linear measurements |
| (32) | CV range 1–7% | |
| (29) | Inter-observer correlation coefficient: 0.94 | |
| (14) | ICC: 0.96 | |
| MFT | (14) | Few and ambiguous data on accuracy and after reliability: |
| Weak correlation with CT measurements (Lin’s correlation coefficient =0.18) | ||
| Low intra- and inter-reader agreement values (ICC =0.17–0.51) | ||
| (33) | Liu et al. reported strong ICC coefficient for inter- (0.89) and intra- (0.97) operator agreement | |
| PFT | Few and ambiguous data on accuracy and reliability after available: | |
| (14) | Strong correlation between linear measurements of CT and ultrasound reported by Bazzocchi et al. (Lin’s correlation coefficient =0.87). Low intra- and inter-observer variability (ICC =0.75–0.90) | |
| (34) | Poor correlation with a CT-derived measure of visceral fat area (Pearson correlation coefficient =0.328) reported by Kim et al. | |
| (35) | Intra-observer CV =4.3%; inter-observer CV =6.4% | |
| WFI | Few and ambiguous data available on after accuracy: | |
| (36) | Strong correlation between WFI and the CT-derived ratio of visceral and subcutaneous fat area (r=0.746; P<0.0001) reported by Suzuki et al. | |
| (34) | Very weak correlation between a CT-derived measure of visceral area and WFI (r=0.101) reported by Kim et al. | |
| (31,34,36) | Good reliability: CV less than 9% | |
| Epicardial fat thickness | (37) | Very good correlations of US measurement of epicardial tissue with MRI measurements of epicardial fat thickness (r=0.905) and visceral fat area (r=0.864) |
| (38) | High intra- (ICC ranging between 0.90 and 0.98) and inter-operator (ICC ranging between 0.93 and 0.98) reliability | |
| (38) | Excellent concordance of long-axis and short-axis average epicardial fat thickness measurement with P=0.98 (95% CI, 0.97–0.98) | |
| Peri- and para-renal fat | (39,40) | Two studies showed a great accuracy of ultrasound measures of peri- and para-renal fat with the area of visceral abdominal fat measured with CT (P=0.75; P<0.0001) and with MRI (P=0.77; P<0.0001) |
| (40) | Good inter- and intra-observer reliability of 0.433 and 0.725 (correlation coefficients), respectively | |
| (39) | Intra-operator CV ranging from 4.7% to 6.7%; inter-operator CV of 3.2% | |
| MinASFT | (14) | Very strong correlation between ultrasound measures of MinASFT and CT-linear measurements and high reliability (Lin 0.95–0.98) reported by Bazzocchi et al. |
| (35) | High reliability reported also from Hamagawa et al.: intra-observer CV of 4.3% and inter-observer CV of 4.6%. | |
| MaxASFT | (14) | Very strong correlation between ultrasound measures of MaxASFT and CT-linear measurements and high reliability (Lin 0.95–0.98) reported by Bazzocchi et al. |
| (34) | CV reported to range between 3.5% and 8.1% |
IAFT, intra-abdominal fat thickness; CT, computed tomography; MRI, magnetic resonance imaging; CV, coefficient of variation; ICC, intraclass correlation coefficient; MFT, mesenteric fat thickness; PFT, pre-peritoneal fat thickness; WFI, wall fat index; US, ultrasonography; MinASFT, minimum subcutaneous fat thickness; MaxASFT, maximum abdominal subcutaneous fat thickness.