Imaging Pearls ❯ Liver ❯ Parenchymal Disease: Fatty infiltration, Cirrhosis, and More
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- Attenuation Categorized by Pathologic Fat Content on Unenhanced CT
% pathologic fat content Number of cases Whole liver Resected portion of liver 0 19 64.4 63.9 1-25 54 59.1 59.1 26-50 11 41.9 40.8 >50 4 25.0 26.2
Comparison of CT Methods for Determining the Fat Content of the Liver
Kodama Y et al.
AJR 2007; 188:1307-1312 - Hepatic Steatosis (fatty liver): Causes
- Obesity
- Alcohol consumption
- Parenteral nutrition
- Chemotherapy - "Measurement of attenuation of liver only on unenhanced CT scans is best for prediction of pathologic fat content"
Comparison of CT Methods for Determining the Fat Content of the Liver
Kodama Y et al.
AJR 2007; 188:1307-1312 - What is the best CT technique for prediction of hepatic fat content?
- Noncontrast CT
- Arterial Phase CT
- Corticomedullary phase
- Delayed phase
- A combination of 2 of the above phases - NASH- Nonalcoholic Steatohepatitis: Facts
- Common cause of chronic liver disease characterized by lipid deposition in hepatocytes and varying degrees of inflammation in a patient without a history of excessive alcohol ingestion
- Patients may progress from steatosis to fibrosis and eventually to cirrhosis
- Increased incidence in patients with type II diabetes and obesity
- Increased incidence in patients on select medications including corticosteroids, synthetic estrogens, tamoxifen - "Patients with NASH had a greater liver span and increased caudate to right lobe ratio compared with patients with steatosis alone."
Computed Tomography Features of Nonalcoholic Steatohepatitis with Histopathologic Correlation
Oliva MR et al.
J Comput Assist Tomogr 2006; 30:37-43 - "The CT features of NASH include steatosis, hepatomegaly, and porta hepatis lymph nodes, and the liver to spleen attenuation ratio correlated with the degree of steatosis on histopathology."
Computed Tomography Features of Nonalcoholic Steatohepatitis with Histopathologic Correlation
Oliva MR et al.
J Comput Assist Tomogr 2006; 30:37-43 - " The CT features of NASH include steatosis, hepatomegaly, and porta hepatis lymph nodes, and the liver to spleen attenuation ratio correlated with the degree of steatosis on histopathology. Patients with NASH had a greater liver span and increased caudate to right lobe ratio compared with patients with steatosis alone."
Computed Tomography Features of Nonalcoholic Steatohepatitis with Histopathologic Correlation
Oliva MR et al.
J Comput Assist Tomogr 2006; 30:37-43 - Fatty Infiltration of the Liver: CT Findings
- Liver attenuation lower than the spleen (classic description) or paraspinal muscles
- Vessels are seen thru the zone of fatty liver without distortion or invasion - Fatty Infiltration of the Liver: Common Clinical Presentations
- Diabetes mellitus
- Hyperlipidemia
- Severe hepatitis
- Parental hyperalimentation
- Malabsorption
- Corticosteroids
- Trauma - Fatty Infiltration of the Liver: Facts
- AKA hepatic steatosis
- A sequlae of a range of "insults" to the liver ranging from dietary to trauma to ischemia
- May be diffuse or focal
- When focal can simulate hepatic tumor or other mass like process - Cirrhosis of the Liver: CT Findings
- Nodular liver with increase in size of left lobe with decrease size of the right lobe
- Increased distance between abdominal wall and liver surface
- Nodularity to the liver will vary with nodules often seen on non contrast CT as high density nodules
- Hypervascular nodules on arterial phase are usually hepatoma - Cirrhosis of the Liver: Etiology
- Alcohol abuse
- Hepatitis B and C
- Biliary cirrhosis
- Primary sclerosing cholangitis
- drugs - Cirrhosis of the Liver: Facts
- Chronic liver disease characterized by fibrosis and necrosis of the liver parenchyma
- Alcohol abuse is most common cause in the USA although caused by a range of pathologies
- 6th leading cause of death in the USA - "The inflammatory subtype of nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, is becoming one of the most important causes of chronic liver disease."
Nonalcoholic Fatty Liver Disease
Lall CG et al.
AJR 2008; 190;993-1002 - Nonalcoholic Fatty Liver Disease: Facts
- 7-10% of patients undergoing liver biopsy have nonalcoholic steatohepatitis
- Obesity is the biggest risk factor for nonalcoholic fatty liver disease
- 15-30% of obese patients have nonalcoholic steatohepatitis
- nonalcoholic steatohepatitis will become the most common chronic liver disease in 20 years - What is the current definition of fatty liver on non-contrast CT?
- Liver attenuation =40 HU
- Liver attenuation less than or equal to spleen minus 10HU
- Liver attenuation equal to or less than the spleen
- Liver attenuation less than or equal to the spleen plus 5HU
- Liver to splenic attenuation ration = 1.1 - "It remains unproven whether this subset of individuals with moderate to severe fatty liver disease are truly at greater risk for progression to steatohepatitis or cirrhosis, but longitudinal follow-up is planned to answer this question."
Hepatic Steatosis (Fatty Liver Disease) in Asymptomatic Adults Identified by Unenhanced Low-Dose CT
Boyce CJ et al
AJR 2010; 194:623-628 - "Assessment of liver attenuation by use of unenhanced CT represents an objective and noninvasive means for detection of asymptomatic hepatic steatosis, whereas clinical risk factor assessment is unreliable. Further longitudinal investigation is needed to determine the most appropriate attenuation threshold and the risk for disease progression to steatohepatitis and cirrhosis."
Hepatic Steatosis (Fatty Liver Disease) in Asymptomatic Adults Identified by Unenhanced Low-Dose CT
Boyce CJ et al
AJR 2010; 194:623-628 - "Measurement of attenuation of liver only on unenhanced CT scans is best for prediction of pathologic fat content."
Comparison of CT Methods for Determining the Fat Content of the Liver Kodama Y et al. AJR 2007; 188:1307-1312
- Other etiologies: Bacillary Angiomatosis
- Due to Bartonella henselae in immunocomprimised hosts
- Same organism causes cat scratch fever in non-immunocomprimised hosts
- Commonly referred to in the liver as Peliosis hepatis
- Bacillary Angiomatosis: CT Findings
- Multiple lesions which are often vascular on early phase imaging and may be isodense on later phase images
- Ascite, periportal edema and duct dilatation may occur
- " In patients with a cirrhotic liver, double contrast MR imaging is highly sensitive in the diagnosis of hepatocellular carcinoma of 10 mm or larger, but success in the identification of tumors smaller than 10 mm is still limited."
Hepatocellular Carcinoma in Cirrhotic Livers: Double Contrast Thin Section MR Imaging with Pathologic Correlation of Explanted Tissue Bhartia B et al. AJR 2003;180:577-584
- " Clinically unsuspected HCC is most prevalent with cirrhosis secondary to hepatitis B or C, and, when evaluated at CT, is best detected with triphasic contrast material enhanced helical imaging performed within 67 days before transplantation."
Pretransplantation Surveillance for Possible Hepatocellular Carcinoma in Patients with Cirrhosis: Epidemiology and CT-based Tumor Detection Rate in 430 Cases with Surgical Pathologic Correlation. " Peterson MS et al. Radiology 2000; 21:743-749
- " In CTA techniques using multidetector row CT, MIP is superior to VR for the hepatic arterial evaluation of potential Living Donor Liver Transplantation (LDLT) donors in terms of depicting anatomic variations and postprocessing times."
Evaluation of the Hepatic Artery in Potential Donors for Liver Transplantation by CT Angiography Using MDCT: Comparison of VR and MIP Techniques Byun JH et al. J Comput Assist Tomogr 27(2):125-131
- Other etiologies: Bacillary Angiomatosis
- Due to Bartonella henselae in immunocomprimised hosts
- Same organism causes cat scratch fever in non-immunocomprimised hosts
- Commonly referred to in the liver as Peliosis hepatis
- Bacillary Angiomatosis: CT Findings
- Multiple lesions which are often vascular on early phase imaging and may be isodense on later phase images
- Ascite, periportal edema and duct dilatation may occur