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Review
. 2023 Oct 11;13(20):3171.
doi: 10.3390/diagnostics13203171.

Approach to Imaging of Mediastinal Masses

Jitesh Ahuja  1 , Chad D Strange  1 , Rishi Agrawal  1 , Lauren T Erasmus  2 , Mylene T Truong  1
Affiliations
Review

Approach to Imaging of Mediastinal Masses

Jitesh Ahuja et al. Diagnostics (Basel). .

Abstract

Mediastinal masses present a diagnostic challenge due to their diverse etiologies. Accurate localization and internal characteristics of the mass are the two most important factors to narrow the differential diagnosis or provide a specific diagnosis. The International Thymic Malignancy Interest Group (ITMIG) classification is the standard classification system used to localize mediastinal masses. Computed tomography (CT) and magnetic resonance imaging (MRI) are the two most commonly used imaging modalities for characterization of the mediastinal masses.

Keywords: CT; MRI; imaging; mediastinum.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
ITMIG definition of mediastinal compartments. Sagittal reformatted CT with color overlay shows mediastinal compartment borders: prevascular compartment (orange), visceral compartment (green) and paravertebral compartment (purple).
Figure 2
Figure 2
Hilum overlay sign. Chest radiograph posteroanterior view (A) shows well-marginated mass over right hilum (arrowheads). Hilar vessels (arrow) are seen through the mass, suggesting the mass is either anterior or posterior to the hilum. Chest radiograph lateral view (B) confirms the anterior location of the mass (arrowheads).
Figure 3
Figure 3
Thymic cyst. CT shows a fluid attenuating structure (15 Hounsfield units) in the prevascular mediastinum in the region of thymic bed (arrow).
Figure 4
Figure 4
Pericardial cyst. CT shows a fluid attenuating structure (10 Hounsfield units) in the prevascular mediastinum at the right anterior cardiophrenic angle (arrow).
Figure 5
Figure 5
Thymic cyst. (A) CT shows a well-defined homogeneous structure with density slightly higher than simple fluid (40 Hounsfield units) in the prevascular mediastinum (arrow). MRI (B,C) shows T2 hyperintensity (arrow in (B)) and no enhancement with gadolinium (arrow in (C)) consistent with fluid.
Figure 6
Figure 6
Cystic thymoma. CT (A) shows a mixed attenuation (cystic and solid) mass in the prevascular mediastinum. T2W MRI (B) shows hyperintense cystic component and hypointense solid nodule (arrow in (B)). Post-gadolinium MRI (C) shows enhancement of the solid nodule. Pathology showed cystic thymoma.
Figure 7
Figure 7
Thymic hyperplasia. CT (A) shows diffuse enlargement of the thymus maintaining its triangular or bilobed shape (arrow). Follow-up CT (B) 12 months later shows fatty involution of the thymus (arrow).
Figure 8
Figure 8
Thymic hyperplasia. CT (A) shows a rounded soft tissue mass in the prevascular mediastinum (arrow) in a woman with breast cancer. Differential diagnosis includes thymic epithelial neoplasm or metastatic disease. MRI chest in-phase image (B) shows the mass is isointense to muscle (arrow) and shows drop in signal on opposed-phase image (C) consistent with thymic hyperplasia.
Figure 9
Figure 9
Thymoma. CT shows a well-defined homogeneous soft tissue mass in the prevascular mediastinum (arrow).
Figure 10
Figure 10
Thymoma with pleural drop metastasis. CT (A,B) shows a lobulated soft tissue mass in the prevascular mediastinum (arrow in (A)) and a diaphragmatic pleural nodule in the right lower chest (arrow in (B)).
Figure 11
Figure 11
Thymic carcinoma. CT with soft tissue (A) and lung (B) window show large heterogeneous soft tissue mass in the prevascular mediastinum. Left prevascular lymphadenopathy (arrow in (A)) and well-marginated lung nodules (arrows in (B)) are compatible with metastatic disease.
Figure 12
Figure 12
Primary mediastinal lymphoma. CT (A) shows large heterogeneous soft tissue mass in the prevascular mediastinum. The mass is hypermetabolic on FDG PET-CT (B). Biopsy showed diffuse large B cell lymphoma.
Figure 13
Figure 13
Mature teratoma. CT axial (A) and coronal reformat (B) show a well-defined mass containing soft tissue, fat (arrow in (A)) and calcification (arrow in (B)) in the prevascular mediastinum compatible with mature teratoma.
Figure 14
Figure 14
Nonseminomatous germ cell tumor (NSGCT). CT shows a large heterogeneous mass in the prevascular mediastinum. Biopsy showed teratoma with malignant transformation.
Figure 15
Figure 15
Foregut duplication cyst. CT (A) shows a well-marginated structure in the visceral mediastinum with attenuation values slightly higher than simple fluid. MRI (B,C) show high signal intensity upon T2W imaging (arrow in (B)) and no enhancement upon post-gadolinium imaging (arrow in (C)) consistent with fluid.
Figure 16
Figure 16
Paraganglioma. CT (A) shows a hypervascular mass with central necrosis in the visceral mediastinum behind the left atrium. MRI (B,C) shows the mass is hyperintense compared to muscle upon black blood double inversion MRI (arrow in (B)) and hypervascular upon post-gadolinium imaging (arrow in (C)).
Figure 17
Figure 17
Castleman disease. CT shows hypervascular mass with a focus of calcification (arrow) in the visceral mediastinum. Biopsy showed Castleman disease.
Figure 18
Figure 18
Esophageal carcinoma. CT shows a soft tissue mass in the visceral mediastinum inseparable from the esophagus (arrow). Biopsy showed esophageal carcinoma.
Figure 19
Figure 19
Esophageal gastrointestinal stromal tumor (GIST). CT shows a large heterogeneous mass in the visceral mediastinum inseparable from the esophagus (arrow). Biopsy showed gastrointestinal stromal tumor.
Figure 20
Figure 20
Schwannoma. CT (A) shows a well-defined spherical shaped mass in the left paraspinal region (arrow). MRI (B,C) shows the mass is hyperintense upon T2W imaging (arrow in (B)) and enhances with gadolinium (arrow in (C)).
Figure 21
Figure 21
Extramedullary hematopoiesis. CT shows bilateral paraspinal soft tissue thickening (arrows) in a patient with leukemia and anemia.
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