Answer
CT is the imaging study of choice for evaluating mediastinal lesions. CT is an excellent modality in determining the exact location of the mediastinal tumor, as well as its relationship to adjacent structures. It is also useful in differentiating masses originating in the mediastinum from those encroaching on the mediastinum from the lung or other structures.
CT can be used to differentiate tissue attenuations, and it is highly accurate in differentiating fluid, fat, and calcification. CT helps in assessing the vascularity of mediastinal tumors. CT is better than other cross-sectional imaging in revealing local invasion of adjacent structures by a mass or intrathoracic metastases. Fat-fluid levels are considered highly specific in diagnosing mediastinal, mature teratomas (though these are uncommon).
Conventional imaging modalities such as CT and MRI can demonstrate only a decrease in lesion size, and the findings are poor predictors of clinical outcome after treatment for lymphoma. On long-term follow-up, less than 50% of patients with positive CT findings have disease relapse or other evidence of residual tumor.
A study by Albano et al found that pulmonary MALT lymphoma is 18F-FDG avid in most cases, 18F-FDG avidity is correlated with tumor size, and single or multiple areas of consolidation are the most common pattern of presentation of lung MALT lymphoma on CT. [2]
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Posteroanterior (PA) chest radiograph in a man with thoracic non-Hodgkin lymphoma (NHL) shows mediastinal widening due to grossly enlarged right paratracheal and left paratracheal nodes.
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Posteroanterior (PA) chest radiograph in a 16-year-old male adolescent with thoracic non-Hodgkin lymphoma (NHL) shows subtle enlargement of the lower paratracheal lymph nodes.
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Nonenhanced CT scan through the mediastinum shows multiple enlarged lymph nodes in the prevascular space, in the right and left paratracheal region. Nodes in the left paratracheal region cause the trachea to be indented and narrowed on the left side. Note the small, bilateral pleural effusion.
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Nonenhanced CT scan through the mediastinum at the level of the carina shows enlarged tracheobronchial and subcarinal nodes. Note the small bilateral pleural effusion.
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Image shows gross enlargement of subcarinal lymph nodes, which causes the tracheal bifurcation to become splayed, and large hilar nodes. Small bilateral pleural effusions are present.
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Contrast-enhanced axial CT scan in a child shows hypoattenuating, enlarged, subcarinal lymph nodes with splaying of the tracheal bifurcation.
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Posteroanterior (PA) chest radiograph shows a large mass in the right parahilar region extending into the right upper and middle zones, with silhouetting of the right pulmonary artery. Smaller mass is seen in the periphery of the right lower zone. The masses did not respond to a trial of antibiotics. Core-needle biopsy of the larger lesion revealed NHL deposits in the lung.
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Lateral image shows a large mass in the anterior aspect of the right upper lobe of the lung.
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Image shows a normal mediastinum and lungs, destruction of the posterior aspect of the right seventh rib, and soft tissue swelling.
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Radiograph of a patient with non-Hodgkin lymphoma (NHL) of the ribs shows destruction of the rib and soft-tissue mass.
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Tomogram of the right lower chest wall demonstrates the lesion better than previous image in this patient with non-Hodgkin lymphoma (NHL) of the ribs.
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Anteroposterior (AP) view shows a collapsed vertebra in a patient with non-Hodgkin lymphoma (NHL) of the thoracic vertebrae.
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Lateral myelogram shows abrupt tapering of thecal sac caused by compression of soft tissue associated with the lymphomatous deposit in the thoracic vertebrae.
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Posterior bone scan shows no abnormally increased uptake in the thoracic vertebrae. Image shows an unusual pattern of non-Hodgkin lymphoma (NHL) of the upper thoracic vertebra.
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Image shows a right-sided, hemorrhagic pleural effusion. Cytologic and pleural biopsy results confirmed non-Hodgkin lymphoma (NHL).
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Nonenhanced axial CT scan shows biopsy-proved non-Hodgkin lymphoma (NHL) of the thymus, which appears as a hypoattenuating mass in the anterior mediastinum. Note the tracheal displacement to the right.
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This 28-year-old man was being evaluated for fever of unknown origin. Gallium-67 study shows extensive uptake in the mediastinal lymph nodes due to non-Hodgkin lymphoma (NHL).
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T1-weighted coronal MRIs of the thorax in a 55-year-old woman with lower dorsal pain. Note the signal-intensity changes in the body of D12; these are associated with a right-sided, large, paravertebral soft-tissue mass involving the psoas muscle. Biopsy confirmed non-Hodgkin lymphoma (NHL).
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T1-weighted coronal MRIs of the thorax in a 55-year-old woman with lower dorsal pain (same patient as in the previous image). Note the signal-intensity changes in the body of D12; these are associated with a right-sided, large, paravertebral soft-tissue mass involving the psoas muscle. Biopsy confirmed non-Hodgkin lymphoma (NHL).
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Positron emission tomography (PET) CT in an 80-year-old woman with diffuse, large B-cell NHL of the skin and subcutaneous tissues that recently transformed from prior low-grade non-Hodgkin lymphoma (NHL). CT scan of the lower neck shows several subcutaneous nodules of varying size with variable uptake on PET (arrows).
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Positron emission tomography (PET) CT in an 80-year-old woman with diffuse, large B-cell NHL of the skin and subcutaneous tissues that recently transformed from previous low-grade non-Hodgkin lymphoma (NHL) in the same patient as in the previous image. PET shows high level of uptake in the anterior subcutaneous nodule in the chest (white arrows). CT scan of similar nodules (arrowheads) on the anterior left chest does not show PET uptake; these may represent regions of lower-grade NHL. PET image of posterior lesions shows only mild uptake (gray arrow).
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Contrast enhanced axial CT showing extensive right hilar and posterior mediastinal lymphadenopathy due to thoracic NHL.
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Gallium-67 (67Ga) scan shows the intrathoracic lymphoma to be 67Ga avid.
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A PA chest radiograph in a 28-year-old woman who presented with weight loss, showing a cavitating lesion (mimicking tuberculosis) in the left midzone adjacent to the left hilum. Histology confirmed a large-cell NHL.
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An axial CT scan showing an intraparenchymal cavitating lung lesion adjacent to the anterior thoracic wall.
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Axial CT scans showing superior vena caval obstruction secondary to lymphadenopathy from NHL.
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Axial CT scans showing superior vena caval obstruction secondary to lymphadenopathy from NHL.
