Effectiveness of microvascular flow imaging for radiofrequency ablation in recurrent thyroid cancer: comparison with power Doppler imaging.

OBJECTIVES: To compare microvascular flow imaging (MVFI) and power Doppler ultrasonography imaging (PDUS) for detecting intratumoral vascularity in recurrent thyroid cancer both before and after radiofrequency ablation (RFA). METHODS: This retrospective study included 80 patients (age, 57 ± 12 years; 54 women) with 110 recurrent tumors who underwent RFA between January 2021 and June 2023. A total of 151 PDUS and MVFI image sets were analyzed (85 pre-RFA, 66 post-RFA). Two readers assessed vascularity on the images using a four-point scale with a 2-week interval between PDUS and MVFI to estimate inter-reader agreement. Intra-reader agreement was determined by reinterpreting images in reverse order (MVFI-PDUS) after a 1-month gap. Additionally, diagnostic performance for identifying viable tumors after RFA was assessed in 44 lesions using thyroid-protocol CT as a reference standard. RESULTS: MVFI demonstrated higher vascular grades than PDUS, both before (reader 1: 3.04 ± 1.15 vs. 1.93 ± 1.07, p < 0.001; reader 2: 3.20 ± 0.96 vs. 2.12 ± 1.07, p < 0.001) and after RFA (reader 1: 2.44 ± 1.28 vs. 1.67 ± 1.06, p < 0.001; reader 2: 2.62 ± 1.23 vs. 1.83 ± 0.99, p < 0.001). Inter-reader agreement was substantial (κ = 0.743) and intra-reader agreement was almost perfect (κ = 0.840). MVFI showed higher sensitivity (81.5%-88.9%) and accuracy (84.1%-86.4%) than PDUS (sensitivity: 51.9%, p < 0.01; accuracy: 63.6-70.5%, p < 0.04), without sacrificing specificity. CONCLUSION: MVFI was superior to PDUS for assessing intratumoral vascularity and showed good inter- and intra-reader agreement, highlighting its clinical value for assessing pre-RFA vascularity and accurately identifying post-RFA viable tumors in recurrent thyroid cancer. CLINICAL RELEVANCE STATEMENT: Microvascular flow imaging (MVFI) is superior to power-Doppler US for assessing intratumoral vascularity; therefore, MVFI can be a valuable tool for assessing vascularity before radiofrequency ablation (RFA) and for identifying viable tumors after RFA in patients with recurrent thyroid cancer. KEY POINTS: The value of microvascular flow imaging (MVFI) for evaluating intratumoral vascularity is unexplored. MVFI demonstrated higher vascular grades than power Doppler US before and after ablation. Microvascular flow imaging showed higher sensitivity and accuracy than power Doppler US without sacrificing specificity.

Tumor Growth Kinetics Based on Initial Tumor Volume Doubling Time in Active Surveillance of Low-Risk Papillary Thyroid Carcinoma.

Background: During active surveillance (AS) of low-risk papillary thyroid carcinomas (PTCs), the majority remain stable, while some exhibit either an increase or a decrease in tumor diameter or tumor volume (TV). We aimed to evaluate the clinical outcomes and relevant parameters influencing tumor growth kinetics of low-risk PTCs. Methods: This retrospective cohort study evaluated clinical parameters of 402 patients with low-risk PTC sized <2 cm, with a follow-up duration over 3 years. Changes in maximum tumor diameter, TV, and initial TV doubling time (i-TVDT) calculated within 3 years were assessed. A significant change in TV was defined as a change of 75% or more. Results: Of the 402 patients with low-risk PTC, 93.3% (375/402) were diagnosed with papillary thyroid microcarcinoma. During a median follow-up of 5 years, 3.4% (14/402) of patients developed new cervical lymph node (LN) metastasis, and 8.2% (33/402) experienced a maximal diameter increase of ≥3 mm. The i-TVDT of <5 years emerged as an independent risk factor for both maximal diameter growth and new LN metastasis (p < 0.001 and p = 0.04, respectively). Based on TV changes and i-TVDT during AS, we identified four statistically significant tumor kinetic patterns (p < 0.001): Stable (±75% change in TV), Rapid growth (TV increase >75% and i-TVDT <5 years), Slow growth (TV increase >75% and i-TVDT ≥5 years), and Shrinkage (TV decrease >75%). Most of the PTCs remained stable (67.7%), but 17.2% were rapidly growing, with a median onset of growth of 2.0 years. Slowly growing PTCs, comprising 10.9%, grew at a median of 4.3 years. A minority, 4.2%, exhibited shrinkage. In total, 115 (28.6%) patients underwent delayed surgery >12 months after initiating AS. The reasons for delayed surgery included patient preference (51/115, 44.3%), disease progression (31/115, 27.0%), and suspected disease progression, which was referred to as tumor growth not meeting the criteria of an increase of ≥3 mm in maximal tumor diameter (17/115, 14.8%). Conclusion: An i-TVDT of <5 years serves as an important prognostic indicator for disease progression, including tumor growth and new LN metastasis. The four tumor kinetic patterns based on TV changes and i-TVDT assist in guiding personalized decisions early in AS.

Silent pheochromocytoma in adrenal incidentaloma: unveiling clinical and radiological characteristics.

Purpose: Silent pheochromocytoma refers to tumors without signs and symptoms of catecholamine excess. This study aimed to clarify the clinical, radiological characteristics, and perioperative features of silent pheochromocytomas diagnosed after adrenalectomy for adrenal incidentaloma. Methods: Medical records of patients who underwent adrenalectomy for adrenal incidentaloma and were subsequently diagnosed with silent pheochromocytoma between January 2000 and December 2020 were retrospectively reviewed for demographic, diagnostic, surgical, and pathological findings. Results: Of the 130 patients who underwent adrenalectomy for incidentaloma, 8 (6.1%) were diagnosed with silent pheochromocytoma. Almost all patients had no hypertensive symptoms and their baseline hormonal levels remained within normal ranges. All patients exhibited tumor size >4 cm, precontrast Hounsfield unit >10, and absolute washout <60%. Intraoperative hypertensive events were noted in 2 patients (25.0%) in whom antiadrenergic medications were not administered. All patients in the intraoperative hypertensive event group exhibited atypical features on CT, whereas 83.3% of patients in the non-intraoperative hypertensive event group showed atypical features on CT imaging. Conclusion: Silent pheochromocytomas share radiological traits with malignant adrenal tumors. Suspicious features on CT scans warrant surgical consideration for appropriate treatment. Administering alpha-blockers can enhance hemodynamic stability during adrenalectomy in suspected silent pheochromocytoma cases.

Exploring the Benefits of a Reduced-Port Approach in Robotic Posterior Retroperitoneoscopic Adrenalectomy: A Comparative Study of the Two-Port and Three-Port Techniques.

Background: Robotic adrenalectomy has become a surgical treatment option for benign and selected malignant adrenal diseases. We aimed to evaluate the eligibility of two-port robotic posterior retroperitoneoscopic adrenalectomy (PRA) as an alternative to the conventional three-port technique by comparing their surgical outcomes. Materials and Methods: This retrospective cohort study compared the clinicopathological factors and surgical outcomes among 197 patients who underwent two-port or three-port robotic adrenalectomy between 2016 and 2020 in a single tertiary center. For further evaluation, propensity score matching was performed to reduce the selection bias in population characteristics. Results: Patients were categorized by the number of ports (two-port group, 87; and three-port group, 110). The two-port group compared with the three-port group was significantly older (P = .006) and had a smaller mean tumor size (P = .003) and shorter mean operation time (P = .001). Upon comparing clinicopathologic characteristics according to adrenal disorders, for pheochromocytoma, the three-port group had a larger tumor size and a longer operation time. For Cushing's syndrome, the operation time was short and numeric rating scale pain score was significantly low in the two-port group. After propensity score matching, the two-port group had a short operation time and a significantly low postoperative pain score (P < .05). Predictive factors associated with prolonged operation time included male gender, an increased number of ports, and large tumor size. Conclusions: The two-port technique resulted in a shorter operation time and lower pain score compared with the three-port technique. The two-port technique may be a safe alternative to the conventional three-port technique for robotic PRA.

Radiofrequency Ablation for the Treatment of Benign Thyroid Nodules: 10-Year Experience.

Background: Longer follow-up after radiofrequency ablation (RFA) of benign thyroid nodules is needed to understand regrowth and other causes of delayed surgery and long-term complications. Methods: This retrospective study included consecutive patients treated with RFA for symptomatic benign nonfunctioning thyroid nodules between March 2007 and December 2010. RFA was performed according to the standard protocol. We followed up patients at 1, 6, and 12 months, then yearly, until August 2022, and calculated the volume reduction ratio (VRR) at each follow-up. We assessed the incidence of regrowth according to three published criteria, delayed surgery, and complications. The Kaplan-Meier method was used to evaluate the cumulative incidence of regrowth, and univariable and multivariable Cox regression analyses were performed to identify risk factors for regrowth. Results: This study included 421 patients (mean age, 47 ± 13 years; 372 women) with 456 nodules (mean volume, 21 ± 23 mL). The median follow-up period was 90 months (interquartile range, 24-143 months). The mean VRR was 81% at 2 years, 90% at 5 years, and 94% at ≥10 years. Overall regrowth was noted in 12% (53/456) of nodules and was treated with repeat RFA (n = 33) or surgery (n = 4) or left under observation (n = 16). Thyroid nodules with ≥20 mL initial volume had significantly higher risk of regrowth compared with nodules with <10 mL initial volume (hazard ratio, 2.315 [95% confidence interval, 1.183-4.530]; p = 0.014 on multivariable Cox regression analysis). Delayed surgery was performed in 6% (26/421) of patients because of regrowth and/or persistent symptoms (n = 4) or newly detected thyroid tumors (n = 22), one benign and 21 malignant. The overall complication rate was 2.4% (10/421), with no procedure-related deaths or long-term complications. Conclusion: RFA is safe and effective for treating benign thyroid nodules, with a high VRR at long-term follow-up. Regular follow-up after initial success is warranted because of the possibility of regrowth of ablated nodules and the need for delayed surgery in some patients.