Value of F-18-FDG PET/CT Combined with Lung HRCT in Diagnosis of Solitary Pulmonary Intravascular Metastasis

Background. Solitary pulmonary intravascular metastasis is a rare complication of malignant tumors, and accurate diagnosis can improve clinical decision-making, but diagnosing it effectively using conventional techniques is difficult. Purpose. To explore the value of F-18-FDG PET/CT combined with lung high-resolution computed tomography (HRCT) in the diagnosis of solitary pulmonary intravascular metastasis. Methods. F-18-FDG PET/CT, lung HRCT, and follow-up data of 18,143 cancer patients were retrospectively analyzed to select patients with pulmonary vessel involvement besides the primary tumor only. The histopathological or imaging follow-up results were used as the diagnostic criteria for pulmonary intravascular metastasis. Results. A total of 13 patients with 17 pulmonary intravascular metastases were found, of which 9 patients had a single lesion and 4 had double. The SUVmax was 1.1-5.4 (average, 2.4 +/- 1.4), and the length of hypermetabolic metastasis was 5.1-24.1 mm (average, 10.7 +/- 6.5 mm). All the intravascular metastases were located in the terminal pulmonary vessels. Strip or branched pulmonary vessels enlargement with increased metabolism was the main imaging manifestation (15/17, 88.2%), while the other 2 cases only showed strip metabolic enhancement without abnormalities in pulmonary vessels (2/17, 11.8%). Four pulmonary intravascular metastases were confirmed by pathology, and the other 13 cases were diagnosed by imaging follow-up. Conclusion. F-18-FDG PET/CT combined with lung HRCT is an effective technique for the diagnosis of solitary pulmonary intravascular metastasis. High-strip or branched FDG uptake in the distal pulmonary vessel accompanied by corresponding morphological changes in patients with malignant tumors can be used as a specific diagnostic indicator.