Common and uncommon features of focal splenic lesions on contrast-enhanced ultrasound: a pictorial review

Abstract

The characterization of focal splenic lesions by ultrasound can be quite challenging. The recent introduction of contrast-enhanced ultrasound (CEUS) has come to play a valuable role in the field of imaging splenic pathologies, offering the possibility of an ionizing radiation-free investigation. Because CEUS has been incorporated into everyday clinical practice, malignant diseases such as focal lymphomatous infiltration, metastatic deposits, benign cysts, traumatic fractures, and hemangiomas can now be accurately depicted and characterized without the need for further imaging. More specifically, splenic traumatic fractures do not require additional imaging by computed tomography (with ionizing radiation exposure) for follow-up, because splenic fractures and their complications are safely imaged with CEUS. In the new era of CEUS, more patients benefit from radiation-free investigation of splenic pathologies with high diagnostic accuracy.

Keywords: Microbubbles; Neoplasms; Spleen/diagnostic imaging; Ultrasonography/methods; Wounds and injuries.

Figure 1

Zebra sign. A split-screen view. Striations are seen in a normally perfused spleen in the early arterial phase, the CT analog of the zebra sign.

Figure 2

Simple cyst. A: B-mode ultrasound showing a well-circumscribed cystic structure (arrow) with a degree of a posterior acoustic enhancement. B: A split-screen view. The CEUS emphasized the features of the simple cyst (arrow), showing a well-circumscribed, thin-walled mass with minimal posterior acoustic enhancement.

Figure 3

Abscess. A: Contrast-enhanced CT scan showing a hypodense splenic lesion with a thick, irregular wall (arrows). B: CEUS showing no internal enhancement and an irregular wall in the larger abscess, with thickened, enhancing septations in the smaller abscess (arrows).

Figure 4

Granulomatous disease. A: Contrast-enhanced CT scan showing multiple low-density lesions within the spleen, less obvious in the liver. B: Following microbubble contrast administration, the splenic lesions remain hypovascular throughout the CEUS examination but do show some internal vascular enhancement (arrows). The patient depicted had a history of biopsy-proven sarcoidosis

Figure 5

Splenic infarction. A: Contrast-enhanced CT scan, in a pre-assessment for liver transplantation, showing splenomegaly with sharply demarcated low-density area in the posterior-inferior pole of the spleen (arrow). B: A split-screen view. Conventional ultrasound (right side of the screen) shows a hypoechoic, heterogeneous lower pole of the spleen, and CEUS (left side of the screen) shows a total absence of enhancement of the lower pole of the spleen, confirming a large wedge-shaped infarction (arrow). The patient was found to have aortic valve endocarditis.

Figure 6

Splenic trauma. A: B-mode ultrasound showing subtle heterogeneous abnormalities within the spleen (arrows). B: Contrast-enhanced CT scan showing irregular areas of hypodensity within the spleen in keeping with intraparenchymal fractures (arrows). C: A split-screen view. Following microbubble contrast administration, CEUS showed areas of heterogeneous contrast uptake (fracture plane/hematoma) with curvilinear and wedge-shaped areas of hypovascularity extending to the hilum, consistent with fractures (arrows).

Figure 7

Multiple splenic lymphoma. A: Contrast-enhanced CT scan showing hypodense, lobulated soft-tissue lesions (arrows) in a patient who presented with abdominal pain and distension. B: B-mode ultrasound showing that lesions (arrows) are ill-defined and of mixed reflectivity. C: Following microbubble contrast administration, CEUS showed early arterial enhancement and rapid washout (arrows) in the venous phase. The appearances are suggestive of either metastatic disease or lymphoma. Following splenectomy, this was proven to be a case of lymphoma.

Figure 8

Splenic fibrosis. A: In the routine follow-up CT of a lymphoma patient, a new, hypodense lesion was observed. B: B-mode ultrasound showing a hypoechoic lesion (arrow). C: CEUS showing increased arterial enhancement at 20 s and washout after 1 min (arrows). The suggested diagnosis was disease infiltration, and splenectomy was performed. The lesion was histologically proven to be focal fibrosis on a background of chronic inflammatory changes.

Figure 9

Hairy-cell leukemia. A: CT scan showing a rounded, hypodense soft-tissue lesion (arrow). B: On CEUS, the lesion shows poor uptake in the arterial phase (arrows) and is hypodense in comparison with the surrounding tissue, although increasing in contrast in the venous phase (arrows).

Figure 10

Splenic metastasis. A: CT scan showing several hypodense lesions in the liver and spleen, a large dominant lesion, with central necrosis, being evident in the spleen. B: B-mode ultrasound showing that the dominant lesion (within the spleen) was ill-defined and heterogeneous, with possible central necrosis. C: A split-screen view. CEUS showed that the lesion was largely avascular and necrotic, with some septations. This appearance is highly suggestive of necrotic metastases. This patient had disseminated metastatic disease, the primary tumor being identified as renal cell carcinoma.

Figure 11

Splenic hemangioma. A: Contrast-enhanced CT scan showing peripheral enhancement and delayed filling of the splenic lesion, characteristic of a splenic hemangioma (arrows). B: CEUS showing a classic splenic hemangioma (arrows) with avid peripheral enhancement in the early phase (23 s) with some internal filling, similar to the arterial-phase filling seen on CT. After approximately 40 s, the hemangioma filled completely, with an enhancement pattern similar to that of the surrounding spleen. Note the similarity to the venous-phase CT scan of the same patient.

Figure 12

Splenic hamartoma. A: Venous-phase contrast-enhanced CT scan showing a complex enhancing mass with central areas of fluid density and a focus of calcification, causing alteration of the contour of the spleen and retraction of the capsule. B: T2-weighted MRI scan showing that the lesion is heterogeneous, with an isointense to hyperintense signal. C: A split-screen view. CEUS revealed that the lesion showed no internal enhancement, consistent with a splenic hamartoma, as was all of the imaging.

Figure 13

Splenic lymphangioma. A: B-mode ultrasound showing a lobulated well-defined abnormality in the upper aspect of the spleen, with septations and calcifications. B: On CEUS, the lesion is more conspicuous, the lobulated outline and septations being clearly demonstrated (arrow). The central aspect of the lesion shows no contrast enhancement. C: The corresponding CT scan confirmed the septations and foci of calcification.

Figure 14

Splenic pseudoaneurysm identified during the follow-up evaluation of a patient who had experienced low-energy blunt abdominal trauma, with no evidence of pseudoaneurysm formation in the initial CT scan. A split-screen view. CEUS showed a focus of hyperenhancement within the fracture plane, consistent with a pseudoaneurysm.

Figure 15

Splenunculi. A: Non-contrast-enhanced CT scan, performed for hematuria workup, showing a large, well-defined lesion adjacent the spleen (arrow). B: A split-screen view. CEUS showed that the lesion (arrows) was enhanced in a manner identical to that of the adjacent splenic parenchyma, confirming that this was a large splenunculus.