Autoimmune hepatitis (AIH) is a progressive, chronic disease with unknown etiology and can occur both in children and adults. A fluctuating course with overtime worsening liver function is the hallmark of the disease. The laboratory abnormalities include increased transaminases and serum autoantibodies. Distinction from other forms of chronic hepatitis is important because the majority of patients respond to anti-inflammatory or immunosuppressive therapy. Two different types of AIH have been identified: Types I and II that have different set of autoantibodies. The clinical presentation of AIH is variable, ranging from almost no symptoms to debilitating and fulminant disease. Patients with severe disease present with profound jaundice, prolonged prothrombin time (PT), and transaminase levels in the thousands. Physical examination may reveal hepatomegaly, splenomegaly, and signs and symptoms of chronic liver disease. Laboratory abnormalities mainly include elevated transaminases (more striking than bilirubin and alkaline phosphatase). Diagnosis is primarily based on the presence of serum autoantibodies and liver biopsy (plasma cell infiltrates). Imaging findings are often nonspecific, however, can help to monitor acute and chronic serial changes. Due to lack of ionizing radiation and safer contrast media, MR imaging is best suitable for this purpose.

Autoimmune hepatitis (AIH) is a progressive, chronic disease with unknown etiology and can occur in both children and adults. AIH is in fact one of the three major autoimmune disorders: the other two being primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). Variant forms of these diseases are generally called overlap syndromes. Without proper treatment or response to treatment, the overlap syndromes, similar to the isolated AIH, progress to cirrhosis (Fig. 123.1).

AIH and PBC are the most common autoimmune liver disorders and occur, respectively, in 17/100,000 and 25–40/100,000 in Europe and USA with a female predominance (PBC, 95 %, and AIH, 80 %). Patients with the overlap syndromes will present with the symptoms of both hepatitis and cholestasis.

At histology, the findings are mixed and we may see a combination of AIH-PSC or AIH-PBC. Studies suggest that AIH-PBC combination occurs most commonly among the overlap syndromes. The AIH-PSC is mostly observed in children (Fig. 123.2).

Two types of AIH have been described in the literature, which are characterized by different types of autoantibodies. Type I AIH is often associated with various antibodies, including antinuclear antibodies (ANA), antimitochondrial antibodies (AMA), and anti-smooth muscle antibodies (anti-SMA) (see Fig. 123.2a). Type II AIH is mostly associated with anti-liver-kidney microsomal antigen (anti-LKM1).

It is important for radiologists to be familiar with the liver parenchymal disorders, including AIH and its variants, to better recognize the imaging findings and help the clinicians with suggesting the possible diagnosis.

At MR imaging, there may be little to no abnormalities during the earlier stages of the disease as shown in the prior figure. During the advanced stages, the T-weighted images show a liver with irregular edges and generalized atrophy. The T2 signal intensity is much higher than in the normal liver. The portal vein may be enlarged as a sign of portal hypertension. After injection of contrast, the liver may show heterogeneous enhancement. The diffusion-weighted images (DWI) and apparent diffusion coefficient (ADC) demonstrate mildly restricted diffusion throughout the liver (see Fig. 123.1).

Approximately 33 million people worldwide are living with human immunodeficiency virus (HIV) infection, and up to 50 % of HIV-infected individuals are also infected with hepatitis C virus (HCV). Whatever the exact percentage, we have to realize that chronic hepatitis C virus (HCV) coinfection is common in patients with human immunodeficiency virus (HIV) infection.

During the early years without effective treatment for HIV infection, the clinical course of HCV coinfection was likely overshadowed by the high morbidity and mortality of patients with AIDS. With the introduction of highly active antiretroviral therapy (HAART) and its associated improvements in survival, HCV coinfection has now emerged as a significant comorbid disease in patients with HIV. Although the exact mechanism is not completely understood and may or may not be associated with specific HAART use, HCV appears to have a much more progressive course in coinfected patients compared with those with HCV monoinfection. With recent improvements in HCV therapy in patients with coinfection, accurate assessment of liver disease severity is now even more important in the evaluation of HCV.

The gold reference standard for determining hepatic histology is liver biopsy. However, liver biopsy is an invasive procedure that has been associated with complications, and there are concerns regarding sampling error and inter- and intraobserver variation in interpretation. Several authors have developed scoring systems to detect changes of active hepatitis to cirrhosis in patients with HIV/HCV coinfection. Imaging can also play an important role to noninvasively detect such changes.

At MR imaging, during the earlier stages of HIV/HCV coinfection, the liver may rapidly increase in size (hepatomegaly) due to the presence of active infection and edema. The signal intensity throughout the liver will increase on the T2-weighted images. The pre-contrast T1-weighted images are often nonspecific. After injection of contrast, diffuse and patchy enhancement is seen in the arterial phase that fades to isointensity in the delayed phase. Due to hepatomegaly, the portal vein will be compressed and there may be mild splenomegaly (Fig. 124.1a–d). Over relatively a short period of time (only a few years), the early acute liver parenchymal appearance may show dramatic transition into the subacute and chronic changes of fibrosis and cirrhosis. During this period, the MR imaging will show significant contour irregularity, atrophy of some liver segments, hypertrophy of the other liver segments, increase in the size of the portal vein, increased splenomegaly, and extensive collateral formation (Figs. 124.1e–h and 124.2). The MR imaging findings of active inflammation correlate well with the surge in the liver enzymes, such as aspartate transaminase (compare Figs. 124.1a–d and 124.2f).

In a patient with HIV/HCV coinfection, more frequent imaging is necessary to monitor the liver parenchymal changes. MR elastography may also play a role in the future.

Passive liver congestion secondary to increased hepatic venous pressure may accompany congestive heart failure. Congestive hepatopathy (aka nutmeg liver or cardiac cirrhosis) includes a spectrum of hepatic derangements that occur in the setting of right-sided heart failure. Clinically, the signs and symptoms of congestive heart failure (CHF) dominate the disorder.

Distinguishing cardiac cirrhosis from the other forms of hepatitis and Budd-Chiari syndrome is important. Despite its name, cardiac cirrhosis (which usually implies congestive hepatopathy that results in liver fibrosis) rarely satisfies strict pathologic criteria for cirrhosis. The terms congestive hepatopathy and chronic passive liver congestion are more accurate, but the name cardiac cirrhosis has become convention.

Patients present with decompensated right ventricular or biventricular heart failure which causes transmission of elevated right atrial pressure to the liver via the inferior vena cava and hepatic veins. At a microscopic level, venous congestion impedes efficient drainage of sinusoidal blood flow into terminal hepatic venules. As a result, sinusoidal stasis occurs with accumulation of deoxygenated blood, parenchymal atrophy, necrosis, and fibrosis. While systemic venous hypertension appears to be the major factor in producing centrilobular congestion, centrilobular necrosis correlates more closely with decreasing cardiac output in patients with cardiac failure. Causes of congestive hepatopathy mirror the many etiologies of right-sided CHF, including congenital heart disease.

Ultrasound studies may suggest the diagnosis with demonstration of hepatic enlargement with dilatation of the inferior vena cava (IVC) and hepatic veins. CT examinations showed cardiomegaly with cardiac failure and pericardial effusion or thickening with pericardial disease. Also noted were distention of the inferior vena cava (IVC), hepatomegaly, early reflux of contrast medium into the IVC in 21 and hepatic veins in 16, and hepatic perivascular lymphedema in 6. The abnormal patterns are thought to be due to slowing of hepatic blood flow. Confusion with Budd-Chiari syndrome and other forms of multifocal hepatic disease is avoidable with imaging studies.

At MR imaging, marked hepatic venous and IVC dilatations with hepatomegaly are seen on all sequences. The T2-weighted sequences demonstrate a bright liver due to edema and inflammation. After injection, there may be reflux of contrast into the dilated IVC and hepatic veins in the arterial phase. Heterogeneous nutmeg-like enhancement is typically visible in the arterial phase, which persists in the delayed phase images. Restricted diffusion may be present. If liver-specific gadolinium-based contrast agent (gadoxetate or gadobenate) has been injected, the hepatobiliary phase images will demonstrate almost homogeneous uptake of contrast into the hepatocyte and can exclude any underlying malignancy that might be suggested based on the early heterogeneous enhancement (Figs. 125.1 and 125.2).

The imaging findings of congestive hepatopathy are dramatically different from Budd-Chiari syndrome that typically shows narrowed or thrombosed hepatic veins and/or IVC, causing outflow obstruction.

The spectrum of fatty liver disease includes mild steatosis to nonalcoholic steatohepatitis (NASH); NASH often progresses into fibrosis and cirrhosis. Recent decades has witnessed an epidemic increase in nonalcoholic fatty liver disease (NAFLD), which may affect 10–24 % of the general population. Eventually, cirrhosis develops in 20–25 % of patients with NASH and increases the risk for developing hepatocellular carcinoma (HCC). Alcoholic steatohepatitis and NASH are histologically indistinguishable. The criteria for the diagnosis of NASH include alcohol consumption <20 g/day, detailed history obtained independently by three physicians, interrogation of family members, and no hepatitis B or C infection. Apart from fat detection, MRI can also detect and quantify liver iron concentration, noninvasively. Liver fat and iron deposition can coexist. The Dixon-based sequences can accurately determine both.