Ha EJ, et al. Korean J Radiol. 2021 Dec;22(12):2094-2123. https://doi.org/10.3348/kjr.2021.0713

Contrast-enhanced MRI T1 mapping of the brain suggested that sleep was associated with greater brain clearance of gadolinium-based contrast agent, potentially due to greater glymphatic clearance. Background Evaluation of the glymphatic system with intrathecal contrast material injection has limited clinical use. Purpose To investigate the feasibility of using serial intravenous contrast-enh...

Background: Active surveillance (AS) is an alternative to thyroidectomy for the management of low-risk papillary thyroid microcarcinoma (PTMC). However, prospective AS data collected from diverse populations are needed. Methods: This multicenter prospective cohort study enrolled patients from three referral hospitals in Korea. The participants were self-assigned into two groups, AS or immediate surgery. All patients underwent neck ultrasound every 6–12 months to monitor for disease progression. Progression under AS was evaluated by a criterion of tumor size increment by 3 mm in one dimension (3 mm), 2 mm in two dimensions (2 × 2 mm), new extrathyroidal extension (ETE), or new lymph node metastasis (LNM), and a composite outcome was defined using all four criteria. Results: A total of 1177 eligible patients with PTMC (919 female, 78.1%) with a median age of 48 years (range 19–87) were enrolled; 755 (64.1%) patients chose AS and 422 (35.9%) underwent surgery. Among 755 patients under AS, 706 (female 537, 76.1%) underwent at least two ultrasound examinations and were analyzed. Over a follow-up period of 41.4 months (standard deviation, 16.0), 163 AS patients (23.1%) underwent surgery. Progression defined by the composite outcome was observed in 9.6% (68/706) of patients, and the 2- and 5-year progression estimates were 5.3% and 14.2%, respectively. The observed progression rates were 5.8% (41/706) and 5.4% (38/706) as defined by tumor size enlargement by 3 mm and 2 × 2 mm, respectively, and 1.3% (9/706) and 0.4% (3/706) for new LNM and ETE, respectively. No distant metastases developed during AS. In multivariate logistic regression analysis examining variables associated with progression under AS, age at diagnosis <30 years (odds ratio [OR], 2.86; 95% confidence interval [CI], 1.10 − 7.45), male sex (OR, 2.48; 95% CI, 1.47 − 4.20), and tumor size ≥6 mm (OR, 1.89; 95% CI, 1.09 − 3.27) were independently significant. Conclusions: The progression of low-risk PTMC during AS in the Korean population was low, but slightly higher than previously reported in other populations. Risk factors for disease progression under AS include younger age, male sex, and larger tumor size. Clinical trial registration: Clinicaltrials.gov NCT02938702.

Lee JY, et al. Korean J Radiol. 2021 May;22(5):840-860. https://doi.org/10.3348/kjr.2020.0578

Lee MK, et al. Korean J Radiol. 2023 Jan;24(1):22-30. https://doi.org/10.3348/kjr.2022.0894

Background Active surveillance (AS) is an accepted strategy for patients with low-risk papillary thyroid microcarcinoma (PTMC). While previous studies have evaluated the prognostic value of US features, results have been inconsistent. Purpose To determine if US features can help predict tumor progression in patients with low-risk PTMC undergoing AS. Materials and Methods This prospective study enrolled 1177 participants with PTMC from three hospitals between June 2016 and January 2021. Participants were self-assigned to either immediate surgery or AS, and those with two or more US examinations in the absence of surgery were included in the analysis. A χ² test was used to compare estimated tumor progression rate at 4 years between participants stratified according to US features. Multivariable Cox regression analysis was used to assess the association of clinical and US features with overall tumor progression and specific progression criteria. Results Among 699 participants included in the analysis, 68 (mean age, 49 years ± 12 [SD]; 40 female participants) showed tumor progression (median follow-up, 41.4 months ± 16 [SD]). Tumor progression was associated with the US features of diffuse thyroid disease (DTD) (hazard ratio [HR], 2.3 [95% CI: 1.4, 3.7]; P = .001) and intratumoral vascularity (HR, 1.7 [95% CI: 1.0, 3.0]; P = .04) and the participant characteristics of male sex (HR, 2.8 [95% CI: 1.7, 4.6]; P < .001), age less than 30 years (HR, 2.9 [95% CI: 1.2, 6.8]; P = .01), and thyroid-stimulating hormone level of 7 µU/mL or higher (HR, 6.9 [95% CI: 2.7, 17.4]; P < .001). The risk of tumor progression was higher for participants with DTD (14%, P = .001) or intratumoral vascularity (14%, P = .02) than for participants without these features (6%). DTD and intratumoral vascularity were associated with tumor enlargement (HR, 2.7 [95% CI: 1.4, 5.1]; P = .002) and new lymph node metastasis (HR, 5.0 [95% CI: 1.3, 19.4]; P = .02), respectively. Conclusion DTD and intratumoral vascularity were associated with an increased risk of tumor progression in participants with PTMC undergoing AS. Clinical trial registration no. NCT02938702 © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Reuter and the review "International Expert Consensus on US Lexicon for Thyroid Nodules" by Durante et al in this issue.