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--- leversteatos [2025/10/31 07:55] – akestorck
+++ leversteatos [2026/01/13 09:28] (aktuell) – akestorck
@@ Rad 1: / Rad 1: @@
-====== Leversteatos ======
+====== Liver steatosis ======
-===== Summary =====
+**Hepatic steatosis**, also known as **fatty liver disease**, refers to abnormal accumulation of fat within hepatocytes, most commonly manifesting as **non-alcoholic fatty liver disease (NAFLD)**.
-Liver steatosis is characterized by excessive triglyceride accumulation within hepatocytes, either diffusely or focally. It may be alcoholic or nonalcoholic (NAFLD) in origin and can progress to steatohepatitis, fibrosis, or cirrhosis. The condition is often asymptomatic and detected incidentally on imaging. Accurate imaging evaluation allows both detection and quantification of hepatic fat content.
+===== Epidemiology =====
+Hepatic steatosis affects up to 30% of the general population in Western countries, with rising prevalence linked to obesity, diabetes, and metabolic syndrome. Prevalence exceeds 70% in patients with type 2 diabetes and reaches 90% in those undergoing bariatric surgery.
-==== Radiographic Features ====
+===== Clinical presentation =====
+Most cases remain asymptomatic and are detected incidentally on ultrasound or other imaging. Symptomatic patients may report right upper quadrant discomfort, fatigue, or elevated liver enzymes.
+===== Pathology =====
+Steatosis results from impaired fat metabolism, with triglycerides accumulating in >5% of hepatocytes. Macrovesicular steatosis predominates, featuring a single large cytoplasmic fat droplet displacing the nucleus.
-Ultrasound (First-line modality):
+===== Radiographic features =====
-Echogenicity: Diffuse increase in hepatic echogenicity (“bright liver”) with posterior beam attenuation.
+==== Ultrasonography ====
-Vascular blurring: Poor delineation of portal and hepatic veins.
+  * **Hyperechoic liver parenchyma** ("bright liver") compared to kidney or spleen
+  * **Grading**:
-Liver–renal contrast: Liver more echogenic than right renal cortex.
+^ Grade     ^ Features                                      ^
+| Mild      | Slight echogenicity increase                   |
+| Moderate  | Impaired vessel wall visualization             |
+| Severe    | Poor diaphragm/portal vein visibility          |
-Focal changes: Geographic areas of fatty sparing or deposition, commonly near the gallbladder fossa, porta hepatis, or falciform ligament.
+==== Computed tomography ====
-Grading (Qualitative):
+  * **Unenhanced CT**: Liver attenuation <40 HU absolute or >10 HU lower than spleen
+  * **Contrast-enhanced**: Focal sparing appears hyperdense relative to steatotic parenchyma (gallbladder fossa, segment IV)
+  * Dual-energy CT improves quantification
-Mild (Grade I): Slight diffuse echogenicity; normal diaphragm and vessel visualization.
+==== Magnetic resonance imaging ====
-Moderate (Grade II): Moderate echogenicity with mild vessel and diaphragm blurring.
+  * **Chemical shift imaging** (in/out-of-phase): Signal dropout on opposed-phase images (>5% fat)
+  * **Proton density fat fraction (PDFF)**: Gold standard for quantification
+  * **Spectroscopy**: Measures fat fraction directly
-Severe (Grade III): Marked echogenicity with poor visualization of posterior structures.
+===== Treatment and prognosis =====
+Management targets underlying causes (weight loss, diabetes control). Steatosis alone carries excellent prognosis without fibrosis; NASH risks progression to cirrhosis (20-30%).
-CT (Quantification on Non-contrast images):
+===== Differential diagnosis =====
-Attenuation: Decreased hepatic attenuation due to fat (normal ≈ 50–65 HU).
+  * Glycogen storage disease (US: hyperechoic but vessels clear)
+  * Acute hepatitis (diffuse hypoechoic)
+  * Focal fat sparing/deposition mimics mass
+  * Iron overload (high attenuation on CT)
-Quantitative criteria (non-contrast):
+===== References =====
+* [[https://pubs.rsna.org/doi/full/10.1148/rg.266065004|RadioGraphics 2006: Fatty Liver]]
+* [[https://pmc.ncbi.nlm.nih.gov/articles/PMC6824276/|Ultrasound Med 2019]]
+* [[https://ajronline.org/doi/10.2214/AJR.11.7838|AJR Am J Roentgenol 2012]]
+* [[https://pubs.rsna.org/doi/full/10.1148/radiol.2021204288|Radiology 2021]]
+* [[https://pmc.ncbi.nlm.nih.gov/articles/PMC4064084/|World J Gastroenterol 2014]]
+* [[https://www.sciencedirect.com/science/article/abs/pii/S0720048X06004451|Eur J Radiol 2007]]
-Mild steatosis: 30–39 HU.
+> **Medical Disclaimer**: Portions of this content were AI-generated to facilitate rapid knowledge synthesis. Radiologists and clinicians must independently verify all information against peer-reviewed literature, institutional protocols, and patient-specific factors before clinical application.
-Moderate to severe: <30 HU.
-Liver–spleen attenuation difference: >10 HU (liver lower) diagnostic for steatosis.
-Contrast-enhanced CT:
-Not suitable for fat quantification due to variable enhancement.
-May show areas of relative hypoattenuation (focal steatosis) or hyperattenuation (fatty sparing).
-Useful to exclude mass effect or underlying focal lesions.
-MRI (Most sensitive and specific):
-In-phase/out-of-phase imaging:
-Signal loss on out-of-phase images indicates intracellular fat.
-Fat fraction >5% diagnostic.
-MR Proton Density Fat Fraction (PDFF):
-Quantifies hepatic fat accurately; normal <5.5%.
-Distribution patterns: Diffuse, geographic, or nodular; absence of mass effect and preserved vascular structures favor benignity.
-Elastography (US or MR):
-Evaluates coexisting fibrosis or steatohepatitis in NAFLD patients.