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The spleen appears echogenic on US imaging. US is an effective means of assessing for splenic cysts and abscess due to the tissue acoustic impedance differences between solid organs and fluid collections; i.e. echogenic solid structures provide greater acoustic disruption when juxtaposed with echo-free internal fluid collections. Advantages of US included safety due to the absence of ionizing radiation, economical in comparison with other available imaging modalities, bed-side availability for immobile patients, real-time imaging, and multi-axis degrees of freedom allowing for flexibility in isolating a desired image. However, the spleen can be somewhat difficult to image with ultrasound due to its subdiaphragmatic location and the presence of overlying ribs.
Computed Tomography (CT):
CT imaging has the capability to obtain a cross-sectional image of the spleen with more complete and detailed information about its vascularity. CT imaging is useful in the diagnosis of splenic injuries. Splenic hematomas, infarction and parasitic/non-parasitic splenic cysts are readily visualized. Additional informtion about splenic pathology is obtained with contrast enhanced CT, particularly useful in detecting accessory spleens.
Magnetic Resonance Imaging (MR):
For patients allergic to IV contrast, MR is the study of choice. The normal spleen appearance hypointense in relation to normal liver on T1 weighted images. On T2-weighted images, the spleen is hyperintense compared to normal liver. MR imaging can help elucidate more specific parenchymal disease processes, including hemosiderosis and the appearance of Gamna-Gandy bodies. Disadvantages of MR imaging are time of acquisition, expense and availability.
Some patients may not tolerate the MR scan and some have contraindications, such as pacemakers.
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