Applied Radiology

Diagnosis

Metastatic lung carcinoma with malignant pericardial effusion (MPE)

Findings

The CT scan of the lung bases demonstrates a small-to-moderate pericardial effusion (figure 1). The PET scan reveals a halo of increased uptake in the area of the pericardium (figure 2). There are also metastases at the base of the heart and disseminated disease. The patient subsequently developed cardiac tamponade. He underwent an emergent pericardiocentesis. Malignant cells were identified in the pericardial fluid cytology. Bronchoscopic biopsy revealed poorly differentiated non-small cell lung cancer.

Discussion

Metastatic involvement of the heart or pericardium commonly leads to pericardial effusion and may be life threatening. When pericardial effusion develops rapidly, as little as 250 mL may cause tamponade, with subsequent impairment of right ventricular diastolic filling, hypotension, syncope, and death. Emergency pericardiocentesis is essential in this setting. Long-term therapeutic options include creation of a pericardial window or pericardial sclerosis.

The PET scan revealed a band of increased activity encircling the heart and extending superiorly beyond the upper border of the left ventricle. The activity extends to the level of the great vessels reflecting the anatomic border of the pericardium. F-18-fluorodeoxyglucose (FDG) localizes in malignant tissues, in inflammation or infection, and at other sites of high glucose metabolism. Physiologic activity is seen in the myocardium, liver, kidneys, and bladder regions. Intense foci consistent with metastatic disease are noted adjacent to the cardiac margin (figure 2), and the pericardium appears nodular with moderate thickening (figure 3). The presence of a pericardial effusion is suggested by the separation of the pericardium from the inferior border of the left ventricle. By contrast, the normal pericardium is rarely visible on a PET study.

The CT scan (figure 1) revealed pericardial fluid both posteriorly and encircling the heart. CT of the chest provides an excellent means to detect pericardial effusions, pericardial thickening, and masses invading the pericardium. Normally, the pericardium is 1 to 2 mm thick, consisting of soft-tissue density separated from the underlying myocardium by epicardial fat.¹ Small effusions collect posterior to the left ventricle and lateral to the left atrium. With increasing size, fluid accumulates anterior and lateral to the right ventricle. Large effusions form an asymmetric halo around the heart. Simple benign pericardial effusions often have water-density attenuation.² Hemorrhagic effusions usually have higher attenuation, but the attenuation coefficient cannot be relied upon to differentiate malignant from benign effusions.

Metastases to the heart and pericardium are common, discovered at autopsy in 10% to 12% of all patients with malignancies.³ Associated symptoms include dyspnea, cough, and pleuritic chest pain. Unfortunately, these symptoms are nonspecific and may also be seen in cancer patients without pericardial disease. Tumors involve the heart and pericardium by one of several pathways: antegrade or retrograde lymphatic extension, hematogenous spread, transvenous extension, or direct invasion. The most common path is through the mediastinal or hilar lymphatics.⁴ Lung cancer involves the heart or pericardium in as many as 30% of patients, 65% of whom have a pericardial effusion.^3,5 Pericardial effusions are also frequently found in breast cancer, melanoma, and lymphoma.⁶ Nonmalignant pericardial effusions are associated with idiopathic, drug-induced, or radiation-induced pericarditis.

It is important to be aware of the frequent metastatic involvement of the heart and pericardium in lung cancer and other malignancies. Care should be taken to inspect the cardiac margins and pericardium to detect the presence of potentially life-threatening pericardial effusion.

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2. Lee JKT, Sagal S, Stanley RJ: Computed body tomography with MRI correlation. 3rd ed. p 564. Baltimore: Lippincott Williams and Wilkins, 1998.

3. Chiles C, Woodard PK, Gutierrez FR, Link KM: Metastatic involvement of the heart and pericardium: CT and MR imaging. RadioGraphics 21:439-49, 2001.

4. Tamura A, Matsubara O, Yoshimura N, et al: Cardiac metastasis of lung cancer. A study of metastatic pathways and clinical manifestations. Cancer 15:437-442, 1992.

5. Devita JR VT, Hellman S (eds): Cancer Principles and Practice of Oncology. 6th ed., Vol 1. p 2737. Baltimore: Lippincott Williams and Wilkins, 2001.

6. Decamp MM Jr., Mentzer SJ, Swanson SJ, Sugarbaker DJ: Malignant effusive disease of the pleura and pericardium. Chest 112(4 Suppl):291S-295S, 1997.