Distinguishing Recurrent Thyroid Cancer from Residual Nonmalignant Thyroid Tissue Using Multiphasic Multidetector CT

Abstract

BACKGROUND AND PURPOSE: During thyroidectomy incomplete resection of the thyroid gland may occur. This complicates the imaging surveillance of these patients as residual thyroid needs to be distinguished from local recurrence. Therefore, the purpose of this study was to determine if multiphasic multi-detector computed tomography (4D-MDCT) can differentiate residual nonmalignant thyroid tissue and recurrent thyroid carcinoma after thyroidectomy. MATERIALS AND METHODS: In this retrospective study, Hounsfield unit values on multiphasic multidetector CT in precontrast, arterial (25 seconds), venous (55 seconds), and delayed (85 seconds) phases were compared in 29 lesions of recurrent thyroid cancer, 29 with normal thyroid, and 29 with diseased thyroid (thyroiditis/multinodular thyroid). The comparison of Hounsfield unit values among lesion types by phase was performed using ANOVA. The performance of Hounsfield unit values to predict recurrence was evaluated by logistic regression and receiver operating characteristic analysis. RESULTS: All 3 tissue types had near-parallel enhancement characteristics, with a wash-in-washout pattern. Statistically different Hounsfield unit density was noted between the recurrence (lowest Hounsfield unit), diseased (intermediate Hounsfield unit), and normal (highest Hounsfield unit) thyroid groups throughout all 4 phases (P , .001 for each group and in each phase). Dichotomized recurrenceversus-diseased/normal thyroid tissue with univariate logistic regression analysis demonstrated that the area under the receiver operating characteristic curve for differentiating benign from malignant thyroid for the various phases of enhancement was greatest in the precontrast phase at 0.983 (95% CI, 0.954-1), with a cutoff value of #62 (sensitivity/specificity, 0.966/0.983) followed by the arterial phase. CONCLUSIONS: Recurrent thyroid carcinoma can be distinguished from residual nonmalignant thyroid tissue using multiphasic multidetector CT with high accuracy. The maximum information for discrimination is in the precontrast images, then the arterial phase. An optimal clinical protocol could be built from any number of phases but should include a precontrast phase.

2021 Korean Thyroid Imaging Reporting and Data System and Imaging-Based Management of Thyroid Nodules: Korean Society of Thyroid Radiology Consensus Statement and Recommendations

“…In patients with thyroid cancer, pre- and post-contrast CT scans are preferred. Pre-contrast CT scans are useful for the detection of calcifications and ectopic thyroid tissues and for differentiating tumor recurrence from remnant thyroid tissue after thyroidectomy [ 21 233 ]. A contrast-enhanced CT is mandatory to assess LN metastases, which are seen as areas of strong or heterogeneous enhancement and cystic changes [ 21 234 ].…”

Effects of laparoscopic and traditional open surgery on the levels of IL-6, TNF-α, and Gal-3 in patients with thyroid cancer

“…DTC accounts for more than 90% of thyroid cancers. DTC has a relatively low malignancy, and thus its treatment efficacy is more significant; however, cancer cells can often metastasize to the neck, which can aggravate the condition and lead to poor prognostic survival (12). Thyroid cancer resection combined with lymph node dissection can effectively inhibit the development of the patient's disease by removing the tumor tissue, and thereby prolong the patient's disease-free survival.…”

Distinguishing Intrathyroid Parathyroid Adenoma from Colloid Nodules and Papillary Thyroid Carcinomas Using Multiphasic Multidetector Computed Tomography

“…The 4D-MDCT examinations were performed on a multidetector CT scanner (GE Medical Systems, Milwaukee, Wis) with the following parameters: 140 kV, 220 to 250 mA, and a 1.25-mm slice thickness covering the neck from the bottom of the orbits to the arch of the aorta. Four phases including precontrast, arterial (25 seconds), venous (55 seconds), and delayed (85 seconds) phases were acquired as previously described 15 . The 4D-MDCT images were reviewed by a head and neck radiologist (J.M.D.)…”

“…Four phases including precontrast, arterial (25 seconds), venous (55 seconds), and delayed (85 seconds) phases were acquired as previously described. 15 The 4D-MDCT images were reviewed by a head and neck radiologist (J.M.D.) who localized and labeled the various nodules with arrows on the images.…”