대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Radiation pneumonitis caused by transarterial radioembolization

Radiologic Findings

Chest radiograph demonstrates multifocal patchy opacities at both lung fields.
Chest CT demonstrates multifocal GGOs in the lung parenchyma with sparing peripheral/hilar area at both lungs.

This patient was diagnosed with solitary hepatocellular carcinoma with bone metastasis 3 months ago. He underwent angiography with 99mTc-MAA in the proper hepatic artery and scintigraphy demonstrated a hepatopulmonary shunt of 15%. Then he underwent transarterial radioembolization (TARE) for the HCC.
After 3 months, the patient exhibited worsening of dyspnea. Chest PA and CT findings were typically suggestive of radiation pneumonitis due to TARE. He expired 1 month later.

Brief Review

Transarterial radioembolization (TARE) is a technique for the treatment of unresectable hepatocellular carcinoma and liver metastases with catheter-directed intraarterial administration of yttrium-90 (90Y) resin or glass microspheres. This technique uses the dual hepatic blood supply to deliver a therapeutic radiation dose greater than 200 Gy to tumors while delivering less than 10 Gy to the normal liver parenchyma. The average diameter of these microspheres is 29-35μm and lodged in small hepatic arterioles.
After intra-arterial injection of Y-90 microspheres into the liver, a small fraction of the radioactive substance is shunted into the lung via intrametastatic arteriovenous shunts. If a large proportion of the injected radionuclide microspheres is shunted into the lung, the risk of radiation-induced pneumonitis is increased.
In the absence of pathologically proven microsphere deposition, radiation pneumonitis is a diagnosis of exclusion based on clinical, functional, and radiographic findings without other infectious/inflammatory/cytotoxic etiologies. Patients present with nonproductive cough, dyspnea, fever, and bronchoalveolar lymphocytosis and eosinophilia. Functionally, radiation pneumonitis initially presents as a mild restrictive process on pulmonary testing.
Radiographically, radiation pneumonitis presents 1–2 months after therapy with ill-defined patchy opacities and ground-glass nodularity in a asymmetric pattern with relative peripheral/hilar sparing (due to diameter of microshperes). These may resolve or progress toward localized fibrosis, traction bronchiectasis, and focal honeycombing. Late complications include pneumothorax and superinfections.
All undergo initial evaluation to assess for tumor-induced arteriovenous shunting to the lung parenchyma with the use of intraarterial technetium-99m (99mTc) macroaggregated albumin (MAA) administration and quantitative scintigraphy. MAA can pass through tumor-associated arteriovenous shunts and become deposited in the pulmonary vasculature. Radioemboization should be avoided in patients with a lung shunt fraction of 13-20% or higher.

References

1. Chadwick L. Wright, Jeff D. Werner, Jerry M. Tran, et al. Radiation Pneumonitis Following Yttrium-90 Radioembolization: Case Report and Literature Review. J Vasc Interv Radiol 2012; 23:669–674
2. Lourens Bester, Riad Salem. Reduction of Arteriohepatovenous Shunting by
Temporary Balloon Occlusion in Patients Undergoing Radioembolization. J Vasc Interv Radiol 2007; 18:1310–1314
3. Michael Lin. Radiation Pneumonitis Caused by Yttrium-90 Microspheres: Radiologic Findings. AJR 1994;162:1300-1302
4. Jennifer L. Peterson, Laura A. Vallow, Douglas W. Johnson, Complications after 90Y microsphere radioembolization for unresectable hepatic tumors: An evaluation of 112 patients. Brachytherapy 2013; 12:573-579
5 . Hojjat Ahmadzadehfar, Hans-Jürgen Biersack, and Samer Ezziddin. Radioembolization of Liver Tumors With Yttrium-90 Microspheres. Semin Nucl Med 2010; 40:105-121

Keywords

Lung, Embolic, Thromboembolic, Radiation complication,