Protocol for measurement of liver fat by computed tomography

Abstract

To develop a protocol for measurement of liver fat using computed tomography (CT), we conducted a preliminary study with 118 men and 76 women to determine a readily identifiable vertebral landmark at which the CT image displayed both liver and spleen. Analysis of five landmarks revealed that the CT image obtained at the T12–L1 level simultaneously displayed the liver and spleen in 90% of the men and women. The T12–L1 protocol was cross-validated on a sample of 130 men and 113 women. In this sample, we also assessed the regional characteristics of liver and spleen tissue attenuation at the T12–L1 level by subdividing each image into quartiles from anterior to posterior, each of which were further divided into medial and lateral regions. A similar analysis was performed on images located 12 mm above and below T12–L1. The T12–L1 image displayed both liver and spleen in 92% (403 of 437) of the combined study sample. There was a significant ( P < 0.005) stepwise increase in attenuation values [Hounsfield units (HU)] from the inferior to superior image. Although some significant ( P < 0.05) differences were observed between the eight regions by comparison to the whole liver or spleen, the average magnitude of the difference was <2.0 HU for liver and <3.5 HU for spleen. Acquisition of a single CT image at the T12–L1 level is a practical and reliable method for routine measurement of liver fat in research and clinical settings.