Computed tomography appearance of normal nonossified thyroid cartilage: implication for tumor invasion diagnosis.

OBJECTIVE: The objective of this study was to determine the density and homogeneity of the nonossified thyroid cartilage (NOTC) on contrast-enhanced computed tomography (CT) providing preliminary information for future evaluation of cartilage invasion using dual-energy CT.

METHODS: One hundred normal-larynx CT scans were evaluated for the density and homogeneity of NOTC.

RESULTS: The density of the NOTC was homogeneous in all cases. Nonossified thyroid cartilage had higher mean density than contiguous muscle, but there was overlap. In 47 cases, a lucent area was observed at the junction of the ossified and NOTC but not within the NOTC itself. In 11 cases, ossification was observed in only 1 cortex of the thyroid cartilage. Cartilage at the anterior commissure was not ossified in 7 cases.

CONCLUSIONS: Nonossified thyroid cartilage has a homogeneous appearance on contrast-enhanced CT scans, but showed some normal variations that could be mistakenly reported as tumor invasion.