Date Published: April 11, 2018
Publisher: Springer US
Author(s): Marzieh Nejabat, Asha Leisser, Georgios Karanikas, Wolfgang Wadsak, Markus Mitterhauser, Marius Mayerhöfer, Christian Kienbacher, Michael Trauner, Marcus Hacker, Alexander R. Haug.
To investigate [11C]acetate PET-surrogate parameter of fatty acid synthase activity—as suitable tool for diagnosis and monitoring of liver steatosis.
In this retrospective study, data were obtained from 83 prostatic carcinoma patients from 1/2008 to 1/2014. Mean HU was calculated from unenhanced CT of all patients from liver with liver HU less than 40 as threshold for liver steatosis. SUVmax of the liver and of the blood pool in thoracic aorta (as background for calculation of a liver/background ratio [SUVl/b]) was measured. t test was used with a P < 0.05 considered as statistically significant difference and ROC analysis was used for calculating specificity and sensitivity. 19/83 patients (20%) had diagnosis of hepatic steatosis according to CT. Uptake of [11C]acetate was significantly higher in patients with hepatic steatosis as compared to control group (SUVmax 7.96 ± 2.0 vs. 5.48 ± 2.3 [P < 0.001]). There was also a significant correlation between both SUVmax (r = − 0.52, P < 0.001) and SUVl/b (r = − 0.59, P < 0.001) with the density (HU) of the liver. In ROC analysis for detection of liver steatosis SUVmax (threshold: 5.86) had a sensitivity of 94% and specificity of 69% with an AUC of 0.81. Increasing body mass index is correlated with the severity of steatosis. We showed for the first time that hepatic steatosis associates with increased [11C]acetate uptake. Also, severity of steatosis correlates with [11C]acetate uptake. [11C]acetate uptake PET seems promising for the assessment of liver steatosis. The online version of this article (10.1007/s00261-018-1558-4) contains supplementary material, which is available to authorized users.
According to the inclusion criteria 43/126 patients were excluded from the study due to: liver lesions, known hepatitis B and/or C, incomplete laboratory data, lack of unenhanced CT, and additional disease or therapies that may affect liver parenchymal enhancement. The study population included 83 patients (mean age 68.9, range 48–94). 19/83 patients were defined as steatosis patients and 64 patients as controls. This data indicates a prevalence of steatosis in about 20% in our study population.
According to recent guidelines published by the American Gastroenterological Association in patients with the incidental findings of fatty liver (mostly in ultrasound), liver biopsy is not recommended in the absence of risk factors such as diabetes mellitus, hyperlipidemia, hypertension and/or central obesity. These patients should be followed by an imaging method and by monitoring of biochemical data . Several imaging methods are available for diagnosis and follow-up of NAFLD, all of them with specific drawbacks. Ultrasound is machine and operator dependent and especially in patients with central obesity and thick adipose tissue, it cannot be used properly . CT has been shown to have less accuracy in detecting mild steatosis in comparison to more advanced steatosis . MRI is prone to artifacts and has difficulties in providing reliable vendor-independent quantitative data. As mentioned before, despite its increasing use, Fibroscan does not reflect the metabolic situation . Further on, results of Fibroscan show a wide variation in sensitivity ranging from 77% to 100% and specificity ranging from 78% to 98% .