Radioiodine-Induced Salivary Gland Damage Detected by Ultrasonography in Patients Treated for Papillary Thyroid Cancer: Radioactive Iodine Activity and Risk.

Background: An important side effect of radioactive iodine (RAI) therapy in patients treated for papillary thyroid cancer (PTC) is chronic sialadenitis. Neck ultrasonography (US) easily recognizes radioiodine-induced salivary gland abnormalities. The objectives of this study were to determine the prevalence of US-detected sialadenitis caused by RAI and to identify the risk factors associated with this damage. Methods: This nonconcurrent cohort study includes all PTC-operated patients who were treated with RAI between 2007 and 2017 and were systematically evaluated with preoperative and follow-up neck US that included targeted exploration of the major salivary glands. Patients with pre-existing salivary gland diseases were excluded. The anatomical damage (diminished glandular volume, wavy contours, hypoechogenicity, and heterogeneity) was qualitatively assessed and compared with the preoperative study. RAI activity, sex, age, and preparation method were evaluated as risk factors using univariate and multivariate analyses with logistic regression. Results: Enrolled in this study were 570 patients who received a median RAI activity of 3700 MBq (100 mCi). On US, we found 143 patients (25.1%) with damage in at least one of their salivary glands: all had parotid damage (77 bilaterally) and 14 (9.8%) also had submandibular gland damage (7 of them bilaterally). The multivariate analysis indicated that the risk of sialadenitis was significantly (p < 0.01) correlated with both RAI activity and sex (14.1% of males vs. 28.5% of females). However, the main risk factor was RAI activity; no injury was detected in 156 patients who received 1110 MBq (30 mCi) and 1850 MBq (50 mCi) of RAI. In the groups of patients receiving 3700 MBq (100 mCi), 5550 MBq (150 mCi) and ≥7400 MBq (≥200 mCi), atrophy was found in 21%, 46.9%, and 77.7% of patients, respectively. Age and preparation method were not related to an increased risk of atrophy in this study. Conclusions: Chronic sialadenitis is common and affects approximately one fourth of patients who receive 3700 MBq (100 mCi) or higher RAI activity. The main risk factor for this injury is the total RAI activity administered. By using the lowest effective activity possible, irreversible anatomical damage in salivary glands can be minimized. US is an excellent tool to diagnose post-RAI atrophy.

Prospective validation of the ultrasound based TIRADS (Thyroid Imaging Reporting And Data System) classification: results in surgically resected thyroid nodules.

OBJECTIVE: To assess performance of TIRADS classification on a prospective surgical cohort, demonstrating its clinical usefulness. METHODS: Between June 2009 and October 2012, patients assessed with pre-operative ultrasound (US) were included in this IRB-approved study. Nodules were categorised according to our previously described TIRADS classification. Final pathological diagnosis was obtained from the thyroidectomy specimen. Sensitivity, specificity, positive/negative predictive values and likelihood ratios were calculated. RESULTS: The study included 210 patients with 502 nodules (average: 2.39 (±1.64) nodules/patient). Median size was 7 mm (3-60 mm). Malignancy was 0 % (0/116) in TIRADS 2, 1.79 % (1/56) in TIRADS 3, 76.13 % (185/243) in TIRADS 4 [subgroups: TIRADS 4A 5.88 % (1/17), TIRADS 4B 62.82 % (49/78), TIRADS 4C 91.22 % (135/148)], and 98.85 % (86/87) in TIRADS 5. With a cut-off point at TIRADS 4-5 to perform FNAB, we obtained: sensitivity 99.6 % (95 % CI: 98.9-100.0), specificity 74.35 % (95 % CI: 68.7-80.0), PPV 82.1 % (95 % CI: 78.0-86.3), NPV 99.4 % (95 % CI: 98.3-100.0), PLR 3.9 (95 % CI: 3.6-4.2) and an NLR 0.005 (95 % CI: 0.003-0.04) for malignancy. CONCLUSION: US-based TIRADS classification allows selection of nodules requiring FNAB and recognition of those with a low malignancy risk. KEY POINTS: • TIRADS classification allows accurate selection of thyroid nodules requiring biopsy (TIRADS 4-5). • The recognition of benign/possibly benign patterns can avoid unnecessary procedures. • This classification and its sonographic patterns are validated using surgical specimens.

An ultrasonogram reporting system for thyroid nodules stratifying cancer risk for clinical management.

CONTEXT: There is a high prevalence of thyroid nodules on ultrasonographic (US) examination. However, most of them are benign. US criteria may help to decide cost-effective management. OBJECTIVE: Our objective was to develop a standardized US characterization and reporting data system of thyroid lesions for clinical management: the Thyroid Imaging Reporting and Data System (TIRADS). DESIGN: This was a prospective study using the TIRADS, which is based on the concepts of the Breast Imaging Reporting Data System of the American College of Radiology. MATERIALS: A correlation of the US findings and fine needle aspiration biopsy (FNAB) results in 1959 lesions biopsied under US guidance and studied histologically during an 8-yr period was divided into three stages. In the first stage, 10 US patterns were defined. In the second stage, four TIRADS groups were defined according to risk. The percentages of malignancy defined in the Breast Imaging Reporting and Data System were followed: TIRADS 2 (0% malignancy), TIRADS 3 (<5% malignancy), TIRADS 4 (5-80% malignancy), and TIRADS 5 (>80% malignancy). RESULTS: The TIRADS classification was evaluated at the third stage of the study in a sample of 1097 nodules (benign: 703; follicular lesions: 238; and carcinoma: 156). Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 88, 49, 49, 88, and 94%, respectively. The ratio of benign to malignant or follicular FNAB results currently is 1.8. CONCLUSIONS: The TIRADS has allowed us to improve patient management and cost-effectiveness, avoiding unnecessary FNAB. In addition, we have established standard codes to be used both for radiologists and endocrinologists.