Quantitative analysis of dual-phase enhanced CT in cervical lymph node metastasis of papillary thyroid carcinoma: a comparative study along with pathological manifestations.

PURPOSE: This study aimed to investigate the diagnostic value of dual-phase enhanced computed tomography (CT) in the cervical lymph node metastasis (LNM) of papillary thyroid carcinoma (PTC) by analyzing the dual-phase enhanced Hounsfield units (HUs) of lymph node and sternocleidomastoid muscle, and the ratio and difference. METHODS: The CT arterial-phase and venous-phase imaging data of 143 metastasis-positive lymph nodes (MPLNs) in 88 cases and 172 metastasis-negative lymph nodes (MNLNs) in 128 cases with PTC were retrospectively analyzed. All lymph nodes were confirmed by surgical pathology. The arterial-phase HU of lymph nodes (ANHU), venous-phase HU of lymph nodes (VNHU), arterial-phase HU of the sternocleidomastoid muscle (AMHU) and venous-phase HU of the sternocleidomastoid muscle (VMHU) were measured, and their difference and ratio (ANHU-AMHU, ANHU/AMHU, VNHU-VMHU, VNHU/VMHU) were calculated. The cutoff values and corresponding diagnostic efficacy for diagnosing LNM in PTC were sought by performing the receiver operating characteristic curves. The maximum pathological diameter (MPD) measured on pathological sections of lymph nodes was compared with the maximum transverse diameter (MTD) and maximum sagittal diameter (MSD) and their average values on CT images. RESULTS: The ANHU, and VNHU of MPLNs and MNLNs were 111.89 ± 33.26 and 66.12 (56.81-76.86) (P < 0.001), and 99.07 ± 23.27 and 75.47 ± 13.95 (P < 0.001), respectively. The area under the curve, sensitivity, and specificity of the arterial-phase three parameters (ANHU, ANHU-AMHU, ANHU/AMHU) for diagnosing LNM were (0.877-0.880), (0.755-0.769), and (0.901-0.913), respectively, and the venous-phase three parameters (VNHU, VNHU-VMHU, VNHU/VMHU) were (0.801-0.817), (0.650-0.678), and (0.826-0.901), respectively. Compared with MPD, MTD (Z = -2.686, P = 0.007) and MSD (Z = -3.539, P < 0.001) were significantly different, while (MTD + MSD)/2 was not statistically different (Z = -0.038b, P = 0.969). CONCLUSION: In the differential diagnosis of cervical LNM of PTC by dual-phase enhanced CT angiography, the arterial phase had higher diagnostic efficacy.

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

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.