Hepatocellular carcinoma with intra-atrial tumor extension identified on ^99mTc-labeled macroaggregated albumin single photon emission computed tomography/computed tomography

A 68-year-old male patient presented with loss of appetite and lower limbs swelling for 3 months. Routine biochemical evaluation revealed serum alpha-fetoprotein - 781 ng/ml and total bilirubin - 1.81 mg/dl. Contrast-enhanced computed tomography (CECT) abdomen showed cirrhotic liver and a 7.5 cm lesion in the right lobe of the liver with arterial enhancement and venous washout. There was also evidence of tumor thrombosis into hepatic vein, inferior vena cava (IVC), extending into the right atrium. The patient was planned for transarterial radioembolization (TARE) and underwent ^99mTc-macroaggregated albumin (MAA) scan for pretherapeutic evaluation. Coronal [Figure 1a] and sagittal [Figure 1b] MAA single photon emission computed tomography-computed tomography (SPECT) images showed increased tracer in the tumor in the right lobe and tumor thrombus in IVC extending into the right atrium (black and white arrowheads). Increased extrahepatic MAA uptake noted in bilateral lungs (thin white arrows). Correlative coronal [Figure 1c] and sagittal [Figure 1d] CECT images showed ill-defined hypodense lesion in the right hepatic vein, extending into IVC and right atrium (bold white and black arrowheads). Calculated hepatopulmonary shunt was 52%. Hence, TARE was deferred, and the patient was started on treatment with sorafenib.

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Figure 1 Coronal (a) and sagittal (b) ^99mTc macroaggregated albumin single photon emission computed tomography-computed tomography images show increased tracer in the tumor in the right lobe and tumor thrombus in inferior vena cava extending into the right atrium (black arrow and white arrowhead). Additionally, increased extra-hepatic ^99mTc macroaggregated albumin uptake noted in bilateral lungs (thin white arrows). Correlative coronal (c) and sagittal (d) contrast enhanced computed tomography images shows ill-defined hypodense enhancing lesion in right hepatic vein, extending into inferior vena cava and right atrium (bold white arrow and black arrowhead)

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Pretherapeutic simulation using ^99mTc MAA scintigraphy (planar and/or SPECT) is considered mandatory before administration of ⁹⁰Y-microspheres for the treatment of liver tumors. Shunt calculation is the primary aim of this scan; however, MAA SPECT is also required for assessment of any gastrointestinal shunting and pretherapeutic dosimetric calculations using the differential uptake by normal liver and tumor component.[1]

Careful assessment of the tracer uptake is required for better delineation of tumor and to avoid any gastrointestinal complications secondary to ⁹⁰Y-micropsheres. Extra-hepatic uptake is better seen on SPECT than planar images and could either be due to uptake in digestive tract, gall bladder, coil embolization site, or hepatic vasculature. Uptake in the vasculature most commonly is seen in the portal vein, hepatic artery, hepatic vein, or falciform artery.[2] Uptake in the portal vein, hepatic vein, or IVC is usually secondary to intravascular tumor thrombus. Vascular invasion is recognized as an adverse prognostic factor in hepatocellular carcinoma (HCC) with limited treatment options.[3] TARE, unlike transarterial chemoembolization (TACE), is not an absolute contraindication for HCC with major vessel invasion and has shown modest benefits in selected patients.[4] The patient with tumor thrombosis in hepatic vein extending into IVC has a worse prognosis compared to the tumor thrombus in hepatic vein or portal vein alone.[5] Studies have shown that IVC invasion by tumor is associated with higher lung shunting compared to patients with HCC and no identifiable thrombus.[6]

HCC extending through hepatic vein and IVC into the right atrium is very rare with an incidence of 0.6–4%.[6] These patients have an extremely dismal prognosis with median survival up to 4 months from diagnosis.[7] Surgery whenever possible is the modality of choice and shown survival benefit compared to TACE which has not shown any improvement in prognosis.[8] Experiences with TARE in these subsets of patients have not been reported in literature, probably due to lower median survival or even higher lung shunting, as seen in our case.