"Aetiology "
"T1: hyperintense"
"T2: mildly hyperintense"
"FDG-PET: liver uptake is not altered by the presence of steatosis 6"
"percentage of signal intensity loss >10% is highly specific for steatosis 21."
"Sonoelastography (e.g. FibroScan, acoustic radiation force imaging (ARFFI), can assess the degree of accompanying fibrosis by measuring tissue stiffness 10."
"Requires both in-phase (IP) and out-of-phase (OOP) imaging to be adequately assessed 1,16. Fatty liver appears:"
"IP/OOP imaging: signal drop out on OOP imaging"
"IP/OOP imaging: signal drop out on OOP imaging"
"On IP/OOP imaging, signal loss is demonstrated when there is 10-15% fat fraction with maximum signal loss occurring when there is 50% fatty infiltration of the liver 16. In situations in which there is >50% fatty infiltration, the out-of-phase sequence paradoxically becomes less hypointense than at 50%. This happens because there are relatively fewer water molecules to cancel out the fat signal. Chemical shift artifact at the parenchyma-vessel interface aids in detecting this situation 13. Iron deposition can mask steatosis on IP/OOP imaging 16."
"On IP/OOP imaging, signal loss is demonstrated when there is 10-15% fat fraction with maximum signal loss occurring when there is 50% fatty infiltration of the liver 16. In situations in which there is >50% fatty infiltration, the out-of-phase sequence paradoxically becomes less hypointense than at 50%. This happens because there are relatively fewer water molecules to cancel out the fat signal. Chemical shift artifact at the parenchyma-vessel interface aids in detecting this situation 13. Iron deposition can mask steatosis on IP/OOP imaging 16."
"Another method to quantify the grade of steatosis can be made by taking the relative IP and OOP values of the liver and the spleen, using the following formula (percentage of signal intensity loss) 21:"
"[(Liver IP / Spleen IP) - (Liver OOP / Spleen OOP) ] / [(Liver IP / Spleen IP)] x 100"
"[(Liver IP / Spleen IP) - (Liver OOP / Spleen OOP) ] / [(Liver IP / Spleen IP)] x 100"
"liver IP: signal intensity value in a liver ROI (in-phase)"
"spleen IP: signal intensity value in a spleen ROI (in-phase)"
"liver OOP: signal intensity value in a liver ROI (out-of-phase)"
"liver OOP: signal intensity value in a liver ROI (out-of-phase)"
"spleen OOP: signal intensity value in a spleen ROI (out-of-phase)"
"spleen OOP: signal intensity value in a spleen ROI (out-of-phase)"
"If PSIL is >6%, the diagnosis of hepatic steatosis can be made 21."
"MRI IP/OOP imaging shows a signal drop when fat-fraction >10-15% 16"
"On IP/OOP imaging, signal loss is demonstrated when there is 10-15% fat fraction with maximum signal loss occurring when there is 50% fatty infiltration of the liver 16. In situations in which there is >50% fatty infiltration, the out-of-phase sequence paradoxically becomes less hypointense than at 50%. This happens because there are relatively fewer water molecules to cancel out the fat signal. Chemical shift artifact at the parenchyma-vessel interface aids in detecting this situation 13. Iron deposition can mask steatosis on IP/OOP imaging 16."
"MR spectroscopy: accurate quantitative non-invasive assessment of hepatic steatosis 8"
"MR elastography: shows promise as a method for assessing accompanying hepatic fibrosis 9"
"Dixon quantification sequence"
"Hepatic steatosis calculator for CT & MRI, with report generator - Rad At Hand"
Expected headings
"Aetiology "
"Grading"
"External links"
"Hepatic steatosis is due to the abnormal accumulation of lipids, particularly triglycerides, within hepatocytes 3,4. These are found in both small and large vesicles. Macroscopically, the liver is enlarged, yellow and greasy. Steatosis can lead to fibrosis and cirrhosis."
"drugs: amiodarone, methotrexate, chemotherapy (e.g. tamoxifen)"
"there is potential for missing mild hepatic steatosis on ultrasound if there is concurrent chronic renal disease, which increases the echogenicity of the kidneys; if there is any question that the patient may have a chronic renal disease, comparison of the left kidney with the spleen may be useful"