Superior vena cava obstruction caused by a primary mediastinal large B-cell lymphoma

Shifeng Yang, MD1; Hongwu Liu, MD1; Wei Fang, MD2; Xi Zhao, MD3
1 Department of Radiology, Shandong Provincial Hospital, Jinan, P. R. China
2 Department of Radiology, Yidu Central Hospital, Yidu, P. R. China
3 Siemens Healthineers, China

A 25-year-old male patient, suffering from chest congestion, recurrent coughing and facial edema, was admitted to the hospital. CT examination revealed a non-enhanced right para-mediastinal soft tissue mass in the superior mediastinum, invading the superior vena cava (SVC) and the right atrium. A tumor biopsy revealed a primary mediastinal large B-cell lymphoma. A three-phase chemotherapy was effectively carried out and the tumor had shrunk. The symptoms, however, persisted. A dynamic 4D spiral CT scanning was requested for further evaluation.

In the CT, the segment of the SVC below the azygos arch was not seen, suggesting an obstruction. The azygos vein, the inferior hemiazygos vein, the right internal thoracic vein and the right posterior intercostal veins (1–6, 9–10) were significantly dilated, presumably draining blood into the inferior vena cava (IVC). The upper segment of the IVC drained into the right atrium. The small residual tumor and a large amount of right-sided pleural effusion were also observed.

Contrast enhanced axial images prior to chemotherapy, axial and corona images after three-phase chemotherapy, show that the right para-mediastinal soft tissue mass in the superior mediastinum has shrunk.

Courtesy of Shandong Provincial Hospital, Jinan, and Yidu Central Hospital, Yidu, P. R. China

Fig. 1: Contrast enhanced axial images prior to chemotherapy (Figs. 1a and 1b), axial (Figs. 1c and 1d) and coronal (Fig. 1e) images after three-phase chemotherapy, show that the right para-mediastinal soft tissue mass in the superior mediastinum has shrunk. The right-sided pleural effusion however has increased.

Cinematic rendering VRT image show significantly dilated azygos vein, inferior hemiazygos vein, right internal thoracic vein and right posterior intercostal veins.

Courtesy of Shandong Provincial Hospital, Jinan, and Yidu Central Hospital, Yidu, P. R. China

Fig. 2: Different views of cinematic rendering VRT images, using different presets, show significantly dilated azygos vein, inferior hemiazygos vein, right internal thoracic vein and right posterior intercostal veins (1–6, 9–10). The segment of the superior vena cava (SVC) below the azygos arch is not shown, suggesting an obstruction. The upper segment of IVC drains into the right atrium.

SVC obstruction is mostly caused by malignancies, such as mediastinal lymphomas.[1] Multiple collateral venous pathways develop to bypass the obstruction. The location and severity of the SVC obstruction, superimposed thrombosis, a mediastinal mass or lymphadenopathy, collateral vessels, associated lung masses and pleural effusion can be exquisitely displayed by contrast enhanced CT. In this case, a low dose Dynamic 4D CTA is performed using Adaptive 4D Spiral scanning to acquire images at multiple time points with defined intervals. 

This facilitates a time-resolved inspection of the thoracic vascular system and makes wrong bolus timing highly unlikely. Lower kV and mAs settings (80 kV, 60 mAs) for each time point acquisition are applied to improve contrast-to-noise ratio (CNR) and to reduce radiation dose. Although only 40 mL of contrast agent are used, the venous collaterals are clearly demonstrated in the fused temporal maximum intensity projections (tMIP). The isotropic resolution provided by the Dual Source CT scanner, SOMATOM Force, achieves optimal image quality, improves diagnostic confidence and aids in planning the necessary therapy.

Scanner

Scan area

Thorax

Scan mode

Adaptive 4D Spiral

Scan length

222 mm

Scan direction

Shuttle

Scan time

37.5 s

Tube voltage

80 kV

Effective mAs

60 mAs

Dose modulation

CARE Dose4D

CTDIvol

35.1 mGy

DLP

722.7 mGy cm

Rotation time

0.25 s

Slice collimation 

48 x 1.2 mm

Slice width

1.5 mm

Reconstruction increment

1.0 mm

Reconstruction kernel

Br36

Contrast

350 mgL/mL

Volume

40 mL + 40 mL saline

Flow rate

5 mL/s

Start delay

4 s