Triple-phase contrast-enhanced computed tomography findings for feline cranial mediastinal tumors: Pilot study.

[OBJECTIVE] Thymoma and mediastinal lymphoma (ML) are the most common cranial mediastinal masses in cats. Considering differences in treatment and prognosis, accurate antemortem diagnosis is essential. However, fine-needle aspiration can be inconclusive. Computed tomography (CT) is often used as a diagnostic tool, though apparently no previous studies have directly compared CT findings for thymoma and ML. This pilot study was a preliminary investigation of using CT to differentiate thymoma from ML in cats.

[ANIMALS AND PROCEDURE] Six cats diagnosed with either thymoma or ML underwent triple-phase contrast-enhanced CT. Parameters assessed included changes in CT attenuation across contrast phases and enhancement patterns.

[RESULTS] Thymomas exhibited peak enhancement during the equilibrium phase with heterogeneous contrast patterns, whereas MLs enhanced rapidly in the arterial phase and peaked in the venous phase with homogeneous contrast distribution.

[CONCLUSION AND CLINICAL RELEVANCE] We suggest that the contrast-enhancement patterns and variations in CT values in triple-phase contrast-enhanced CT scans may be key to differential diagnosis of thymoma ML in cats. However, this pilot study had a small sample size and the objective of proposing hypotheses. Large-scale studies are needed to test this hypothesis.