Table 1.
Definitions of normal liver fat using different approaches.
| Study | Year | N | Subjects | Normal Value |
|---|---|---|---|---|
| Biochemical | ||||
| Laurell S [21] | 1971 | 3 | Healthy subjects | 2.0 g/100 g of dry tissue weight |
| Donhoffer H [15] | 1974 | 107 | Unselected cadavers | 5.5 g/100 g of wet tissue weight |
| Histology | ||||
| Kleiner DE [17] | 2005 | 576 + 162 | Adults and children | Macroscopic fat in <5% of hepatocytes |
| Brunt EM [3] | 2011 | 976 | Adults | Macroscopic fat in <5% of hepatocytes |
| Bedossa P [19] | 2012 | 679 | Morbidly obese adults | Macroscopic fat in <5% of hepatocytes |
| CT | ||||
| Piekarski J [22] | 1980 | 100 | Healthy subjects | 50–57 HU or 8–10 HU higher than spleen |
| 1H-MRS | ||||
| Szczepaniak LS [23] | 2005 | 345 | Population-based, healthy subjects | <5.56% |
| Petersen KF [24] | 2006 | 170 | Healthy subjects | <3.0% |
| MRI-PDFF | ||||
| Fishbein MH [25] | 1998 | 28 | Healthy subjects | <9.0% |
| US | ||||
| Joseph AE [26] | 1978 | 60 | Adults referred to gastroenterologist | Absense of echogenicity or brightness of the liver |
| Saveymuttu SH [27] | 1985 | 490 | Adults referred to gastroenterologist | Absense of echogenicity or brightness of the liver |
1H-MRS, proton magnetic resonance spectroscopy; CT, computed tomography; HU, Houndsfield Unit; MRI-PDFF, magnetic resonance imaging-determined proton density fat fraction; US, ultrasound.