Contrast-enhanced ultrasound pattern of splenic metastases - a retrospective study in 32 patients.

Purpose: To characterize the pattern of contrast-enhanced ultrasonography (CEUS) in splenic metastases compared to standard B-mode ultrasonography. Materials and Methods: Between January 2004 and March 2009, about 50,000 abdominal ultrasound examinations were performed, and n = 279 (< 0.6%) of focal splenic lesions were detected of which n = 32 (11.5%) were highly suggestive for splenic metastases of various solid tumors. The number of lesions, size, echogenicity, rim appearance, presence of halo sign and necrosis were recorded via B-mode sonography. Contrast enhancement was determined in the arterial phase (5 - 30 sec) and parenchymal phase (3 - 5 min). B-mode sonography and CEUS were compared in terms of the visibility of splenic metastases. All data was evaluated retrospectively. Results: On B-mode sonography lesions were solitary n = 18 (56%), multiple n = 14 (44%), < 2cm n = 11 (34%), <= 2 cm n = 21 (66%), hypoechoic n = 14 (44%), isoechoic n = 12 (38%) and hyperechoic n = 6 (19%), with regular rim appearance n = 27 (84%), and with irregular rim appearance n = 5 (16%). During the arterial phase CEUS lesions were hypoechoic n = 21 (66%), isoechoic n = 2 (6%), hyperechoic n = 1 (3%) and complex n = 8 (25%). During the parenchymal phase lesions were hypoechoic n = 24 (75%) and complex n = 8 (25%). CEUS provided improved visualization of splenic metastases in n = 12 (38%) cases. Conclusion: CEUS of splenic metastases is characterized by reduced contrast enhancement in both the arterial and the parenchymal phase in most cases. Moreover, CEUS improved the visualization of splenic metastases in about 40% of cases in comparison to standard B-mode sonography.