Diagnostic potential of ^99mTc-macroaggregated albumin scintigraphy in the diagnosis of hepatopulmonary syndrome: Insights from two case studies and critical review of literature

Hepatopulmonary syndrome (HPS) is a rare pulmonary vascular complication of chronic liver disease characterized by dilatation of pulmonary capillaries leading to vascular shunting and systemic hypoxemia. Diagnosis of HPS requires documentation of intrapulmonary vasodilation (IPVD), the two most common imaging studies performed for the detection of IPVD include transthoracic contrast echocardiography (TTCE) and 99m-Tc-macroaggregated albumin scintigraphy (^99mTc-MAA scan). TTCE has high sensitivity and thus, is the preferred initial investigation, while ^99mTc-MAA scan is highly specific and plays an adjuvant role in diagnosis. ^99mTc-MAA scan can, however, identify some cases of HPS not apparent on TTCE and can also quantify the shunt fraction. The current study describes the utility of ^99mTc-MAA scan in the detection of IPVD in two suspected cases of HPS. (author)