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CT Artifacts

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Answer to - Spleen Focal Lesions

Focal lesions of the spleen can be classified as benign or malignant. Benign lesions are more common, including cysts, infarcts, abscesses, haemangioma, hamartomas and calcifications. Malignant lesions are less frequent and include primary lymphoma, sarcomas and metastatic involvement.

Splenic metastases are very rare and most often appear asymptomatic. The literature reports an incidence in autopsy of 0, 6% and in splenectomy of 1, 1%. The most common primary tumour sites are breast and lung, followed by GI tract tumours (oesophagus, stomach and colon), along with few female reproductive organ malignancies (ovary), head and neck neoplasias (pharyngeal) and malignant melanoma. They may appear as a unique focal lesion or multiple lesions within the spleen. Splenic metastases are usually part of wide-spread disseminated malignancies however primary lesions can also occur.

On CT splenic metastases are round masses, very well circumscribed, spontaneously hypodense and fail to enhance after the IV contrast uptake. Carcinoid tumours in general tend to be hypervascularised and may demonstrate intense enhancement during arterial phase. However, spleen metastases from primary neuroendocrine can appear isodense or slightly hyperdense after contrast uptake, since the healthy spleen normally demonstrates heterogeneous enhancement during the parenchymal phase of opacification.

On ultrasound most splenic metastases may appear similar to those depicted in the liver. Most often they have round and well circumscribed shape and are usually hypoechoic. Despite splenic lesions with increase of echogenicity are uncommon in patients with lymphoma, they can often develop as metastatic involvement from neuroendocrine cancers. Commonly these metastases may increase the overall spleen size as well as causing complains of compression or further capsule rupture.

At MRI splenic metastases are typically hyperintense nodules or masses on T2-weighted images and hypo / isointense on T1-weighted sequences. The degree and characteristics of enhancement depend on the nature and type of the underlying primary neoplasm. These features are also applicable to carcinoid tumours.

The SPECT often depicts splenic enhanced spots attributable to metastatic disease.