Value of computed tomography in determining the nature of papillary thyroid microcarcinomas: evaluation of the computed tomographic characteristics

Abstract

Objective: This study was designed to assess the value of computed tomography (CT) in determining the nature of papillary thyroid microcarcinomas (PTMCs).

Methods: Four hundred fifty-two thyroid CT scan cases with pathological data at our department that were performed from January 2011 to January 2012 were analyzed, of which a total of 87 tumors in 73 cases were confirmed as 0.5-1.0 cm diameter PTMC; the CT images of PTMC were analyzed, suitable window width (W) and window level (L) of PTMC were determined, as well as observation of the density and shape of tumors, tumor boundaries before and after contrast enhancement, thyroid edge interruption, calcification, lymph node metastasis, and complications.

Results: Plain scan W 140-180, L 80-120 and contrast-enhanced scan W 160-200, L 110-150 were conducive to the display of PTMC. Among 87 tumors in this group, aside from 10 tumors and intratumoral calcification that were not shown up, plain CT scans of 77 (88.5%) tumors showed homogeneous low density; 59(67.8%) tumors were irregular shaped; 64 (73.6%) tumors showed plain thyroid scan edge interruption; after contrast enhancement, 65 (74.7%) tumor contours were relatively obscure compared with plain scan, and relative low-density range of the tumors narrowed down; 16 (18.4%) tumors were calcified, of which 15 (93.8%) were fine granular calcifications; lymph node metastasis were found pathologically in 18 (24.7%) cases, of which 8 (44.4%, 8/18) cases were CT findings. Among the 10 (11.4%) tumors that did not show up on CT, 7 were complicated with Hashimoto's thyroiditis, 2 were masked by clavicle artifacts, and 1 was masked by nodular goiter.

Conclusion: Plain scan W 140-180, L 80-120 and contrast-enhanced scan W 160-200, L 110-150 were conducive to the display of PTMC. The tumor-shaped irregularity, smaller relative low-density area after contrast enhancement than plain scan, thyroid edge interruption, fine granular calcification, and neck lymph node abnormalities contributed to the diagnosis of PTMC; Hashimoto's thyroiditis, clavicle artifacts, and nodular goiter could mask the tumor, which required adequate attention.