The diagnostic value of spectral CT plain scan after direct lymphangiography in chylothorax as an applicable tool

Abstract

Background: The difficulty in the diagnosis of chylothorax lies mainly in the fine structure of the lymphatic system, and the rupture of microscopic, branched lymphatic vessels which cannot be accurately diagnosed, and spectral computed tomography (CT) scanning can fill the gaps in the diagnosis of chylothorax in terms of the structure of the lymphatic system and the analysis of material composition. The study aims to elucidate the value of spectral CT plain scan after direct lymphangiography (DLG) in the diagnosis of chylothorax.

Methods: From January 2018 to December 2023, we retrospectively recruited 59 patients with clinically confirmed diagnosis of chylothorax, and all patients underwent spectral CT after DLG scanning to observe the abnormalities of lymphatic vessels and the CT findings of other thoracic abnormalities, including abnormal contrast deposition, abnormal changes in the lungs, pleura, thoracic cavity, and mediastinum.

Results: In all the 59 patients with chylothorax, abnormal contrast deposition was seen on spectral CT plain scan after DLG, and could be seen simultaneously in different areas of the superior mediastinum, the mediastinum and both sides of the mediastinum. In terms of anatomical sites, the location of abnormal contrast agent deposition was most common in the left venous angle. And multiple abnormalities in the lungs, the pleura, and the mediastinum were seen.

Conclusions: Spectral CT plain scan after DLG is valuable for the diagnosis of chylothorax. Abnormal distribution of contrast in the lungs, lymphatic ducts and lymphatic trunks in spectral CT plain scan after DLG is an important manifestation of chylothorax, suggesting abnormal distribution and severity of the thoracic organs, lymphatic ducts and lymphatic trunks, and its imaging findings provide a basis for the clinical diagnosis and treatment of the disease.

Keywords: Chylothorax; X-ray computed; lymphography; tomography.

Figure 1

Patient flowchart. CT, computed tomography; DLG, direct lymphangiography.

Figure 2

A 46-year-old woman diagnosed with chylothorax due to recurrent milky fluid aspiration by thoracentesis (triglyceride level: 6.09 mmol/dL), spectral CT after DLG was performed for chylothorax. (A) Axial images of the mediastinal window showed more lipiodol deposition in the area of the left venous angle (white arrow). (B) Axial images of the lung window showed increased bronchial vascular bundles and bronchial wall thickening bilaterally, with chylothorax on the left side (red arrows). (C) Lipiodol deposition in the area of the thoracic duct's course was seen on coronal images (yellow arrow). CT, computed tomography; DLG, direct lymphangiography.

Figure 3

A 26-year-old woman with chylothorax underwent spectral CT after DLG. Axial images of the mediastinal window showed multiple patchy abnormal lipiodol deposits in the right chest wall (white arrow). CT, computed tomography; DLG, direct lymphangiography.

Figure 4

A 36-year-old woman with chylothorax underwent spectral CT after DLG. Axial images of the mediastinal window showed speckled lipiodol deposits visible in the mediastinum (green arrow), around the thoracic aorta (red arrow), and in the right subpleura (yellow arrow). The chylothorax was located on the right side (white arrow). CT, computed tomography; DLG, direct lymphangiography.

Figure 5

A 54-year-old woman with bilateral chylothorax (blue arrows) underwent spectral CT after DLG. (A) Axial images and (B) coronal images of the mediastinal window showed multiple abnormal lipiodol deposits in the mediastinum (red arrow), both lung fields (purple arrows), the right pleura (yellow arrow), and adjacent to the thoracic aorta (green arrow). CT, computed tomography; DLG, direct lymphangiography.

Figure 6

A 53-year-old woman with chylothorax underwent spectral CT after DLG. (A) Axial images of the mediastinal window showed abnormal lipiodol deposition in bilateral venous angle (white arrows). (B) Axial images of the mediastinal window showed abnormal lipiodol deposition in left lung field (red arrow), and chylothorax on the left side (bule arrow). (C) Coronal images of the mediastinal window showed abnormal lipiodol deposition in the thoracic duct alignment area (green arrow). CT, computed tomography; DLG, direct lymphangiography.