Correlation between the size of incidental thyroid nodules detected on CT, MRI or PET-CT and subsequent ultrasound

Natural history and long-term follow-up of incidental thyroid nodules on CT imaging

OBJECTIVES

Incidental thyroid nodules (ITNs) are found in up to 25% of CT scans. Increased use of cross-sectional imaging has contributed to the increased incidence of thyroid cancer worldwide. ITNs pose a management dilemma since nodule malignancy rate is 5%-15% but most cancers are indolent and prognosis in differentiated thyroid cancer is excellent. Study aims are to determine prevalence of ITNs ≥1 cm on CT scans, evaluate reporting practices, assess for emergence of clinically evident thyroid cancer during 13-year follow-up and assess interim nodule growth and clinical outcomes in nodules that were further investigated.

METHODS

Direct image review of 1499 consecutive CT scans that included the thyroid, performed during January 2009 in a large NHS health board was performed. Clinical data up to January 2022 was analysed in 150 patients with at least 1 ITN ≥1 cm.

RESULTS

ITN prevalence was 11% with mean patient age 70 years and mean nodule diameter 17.5 mm. 30% of ITNs were mentioned in the CT report. During the follow-up period 11% proceeded to thyroid ultrasound, 5% fine needle aspiration, and 2% diagnostic hemithyroidectomy with no thyroid malignancy found. One hundred twenty patients (80%) were deceased by the study endpoint, none from thyroid malignancy. No patients presented with clinically evident thyroid malignancy during follow-up.

CONCLUSIONS

None of 150 ITN cases developed clinically evident thyroid malignancy in a 13-year follow-up period with 80% of patients deceased by the study endpoint from non-thyroid causes.

ADVANCES IN KNOWLEDGE

This would suggest that ITNs detected on CT do not require further investigation unless malignant appearances or significant clinical concern for thyroid malignancy.

Thyroid Incidentalomas in Hospitalized Patients With COVID-19: A Single-Center Retrospective Analysis

Context

During the COVID-19 pandemic, both people with underlying diseases and previously healthy people were infected with SARS-CoV-2. In our institute, most hospitalized patients underwent chest computed tomography (CT) to evaluate pulmonary involvement and complication of COVID-19. There are currently limited data regarding thyroid CT incidentalomas in healthy people.

Objective

We aimed to investigate the prevalence and predictors of thyroid incidentalomas among hospitalized patients with COVID-19.

Methods

A single-center retrospective study included hospitalized patients aged ≥15 years with COVID-19 who underwent chest CT during April 2020 and October 2021. Thyroid incidentalomas were reviewed and identified by an experienced radiologist. Logistic regression analysis was used to determine predictors for thyroid incidentalomas.

Results

In the 1326 patients (mean age 49.4 years and 55.3% female) that were included, the prevalence of thyroid incidentalomas was 20.2%. Patients with thyroid incidentalomas were older (59.6 years vs 46.8 years, P < .001) and more often female than those without incidentalomas (63.4% vs 53.2%, P = .003). On multivariate analysis, only female sex (OR 1.56; 95% CI 1.17-2.07) and older age (OR 1.04; 95% CI 1.03-1.05) were significantly associated with thyroid incidentalomas.

Conclusion

In COVID-19 patients, the prevalence of thyroid incidentalomas identified on chest CT was higher (20.2%) than in previous studies in the general population (<1% to 16.8%). Female sex and older age were independent factors associated with thyroid incidentalomas.

Accuracy of 123I Na Thyroid Imaging in calculating thyroid volume

Introduction: Hyperthyroidism is often managed with radioactive iodine therapy. The dose of 131Iadministered to the patient is determined based on the calculated size of the thyroid gland in gram and 24 hour iodine uptake. Ultrasonography is a validated modality for determination of thyroid volume. Though necessary for assessing degree of 123I uptake, nuclear scintigraphy also allows for the capability of estimating thyroid volume. Here we compare volume measurements calculated based on ultrasonography and nuclear scintigraphy in a cohort of hyperthyroid patients. Methods: This prospective study designed to evaluate 110 consecutive hyperthyroidism patients who were undergoing thyroid ultrasound and 123I scintigraphy. Scintigraphy was performed after oral administration of approximately 11 MBq 123Isodium, and uptakes at 2 and 24 hours were measured. At 24 hours, the patients underwent thyroid scan with a nuclear medicine camera with LEHR (low energy high resolution) collimator next to the patient's chin. Thyroid measurements were calculated via the formula for determining a prolate ellipsoid. The formula was modified for RAIU as it is a planar image. Volumes calculated with these two modalities were subsequently analyzed and compared by linear regression. All patients had undergone ultrasonography with an average three months from nuclear scan. All of our patient 131I dosages were based on the thyroid measurements obtained by thyroid scintigraphy. Results: We included 110 patients (95 females, 15 males) with age range 20-95 years and average age 56 +/- 17.4 years old. Diagnoses included 66 patients with nodular goiter, and 44 patients with Graves' Disease. There was a linear relationship between measurement of thyroid gland weight by two modalities which can be explained in the following formula: log US(g) = 0.841 + 0.649*log NM(g). Conclusion: We have validated that this method has helped obtain more accurate measurements of the thyroid gland by thyroid scintigraphy. Additionally, we have derived conversion factors that convert the estimated thyroid volume calculated from thyroid scintigraphy to the expected ultrasound value.

Cost-Effectiveness of Follow-up Ultrasound for Incidental Thyroid Nodules on CT

Background: Thyroid nodules are common incidental findings on CT. Existing professional society recommendations, based primarily on expert opinion, advise follow-up ultrasound for nodules above size cut-offs in patients of all ages. Purpose: To evaluate the cost-effectiveness of current recommendations as well as of other age- and size-based follow-up strategies for thyroid nodules incidentally detected on CT, using a simulation model. Methods: By using a simulation model with 1,000,000 adult patients with nodules measuring ≤40 mm and having no suspicious features, we evaluated size cut-offs from 5 to 25 mm under an age maximum from 25 to 65 years, as well as follow-up versus no follow-up above the age maximum. For each strategy, patient survival was determined by disease-specific and baseline mortality rates, as well as surgical mortality. Costs and quality-adjusted life years (QALYs) were tabulated. A probabilistic sensitivity analysis was performed varying model parameters. Results: All cost-effective strategies recommended no follow-up for patients above the age cut-offs (which varied from 25 to 65 years). In the base case simulation, 8 strategies were cost-effective under a willingness-to-pay threshold of $100,000/QALY. Of these, the strategy yielding the highest QALYs was follow-up for patients <60 years old with nodules ≥10 mm and no follow-up for patients ≥60 years old, with an incremental cost-effectiveness ratio of $50,196/QALY (95% CI $39,233 - $67,479). In the probabilistic sensitivity analysis, if the 10-year disease-specific survival of untreated cancer was >94% of patients with treated cancer, then no follow-up for any nodules was optimal. Conclusion: Follow-up ultrasound for thyroid nodules incidentally detected on CT is likely not cost-effective in older patients. Follow-up for most thyroid nodules in younger patients may be cost-effective. Clinical Impact: Future societal recommendations may account for the limited benefit of obtaining follow-up for incidental thyroid nodules on CT in older patients.

Diagnostic Accuracy of Ultrasonography in Classifying Thyroid Nodules Compared with Fine-Needle Aspiration

Background

Classifying thyroid lesions is challenging; nonetheless, using ultrasonography may allow for accurate diagnosis, differentiation and management of thyroid lesions and help avoid unnecessary biopsy.

Objectives

The main objective of the study is to determine the diagnostic accuracy of ultrasonography in classifying thyroid nodules compared with fine-needle aspiration.

Materials and Methods

This retrospective study included all 68 patients diagnosed with thyroid nodules at King Fahd Hospital of the University, Al Khobar, Saudi Arabia, between June 1, 2014, and November 30, 2016. Parameters were selected based on the Society of Radiologists in Ultrasound criteria. Ultrasonographic features, namely, nodule margins, echotexture, vascularity and calcifications, and fine-needle aspiration cytology (FNAC) results were reviewed by two radiologists blinded to each other's findings and validated by another experienced interventional radiologist. Ultrasonography results were compared against that of FNAC to calculate sensitivity and positive- and negative-likelihood ratios, and the nodule types were compared using Fisher's exact test.

Results

Of the 68 nodules analyzed, 59 were reported as benign using FNAC (specificity = 95%; P < 0.001). Of these 59, 56 were also reported as benign using ultrasonography. The specificity of ultrasonography in determining benign nodules was 94.9%, and the positive- and negative-likelihood ratios were 13.0 and 0.35, respectively. Six of the nine suspicious nodules were confirmed as malignant using FNAC, and the ultrasonography and FNAC findings were strongly associated (P = 0.001). According to the Society of Radiologists in Ultrasound criteria, FNAC and ultrasonography findings were significantly associated for nodule calcification (P = 0.001) and echogenicity (P = 0.001).

Conclusion

The diagnostic specificity of ultrasonography and FNAC in this study are consistent with those reported previously, indicating that ultrasonography reliably classifies thyroid nodules, and thus can assist in the decision-making regarding need for biopsy.

Medullary Thyroid Carcinoma: Do Ultrasonography and F-DOPA-PET-CT Influence the Initial Surgical Strategy?

Background

At the time of diagnosis, one-third of medullary thyroid carcinoma (MTC) patients show lymph node (LN) or distant metastasis. A metastasized MTC requires different surgical strategies.

Objective

This study aimed to determine the value of ultrasound and [18F]fluoro-dihydroxyphenylalanine positron emission tomography with computed tomography (F-DOPA-PET-CT) in localizing MTC, as well as LN and distant metastasis.

Methods

The study included 50 patients (24 males/26 females) with preoperative ultrasound, F-DOPA-PET-CT, and histologically proven MTC. Imaging results were correlated with both preoperative basal calcitonin (bCt) levels and final histology.

Results

Tumors were classified as pT1a:17 (diameter, mean ± standard deviation: 5.8 ± 3.0 mm), pT1b:15 (15.0 ± 3.2 mm), pT2:9 (27.3 ± 7.0 mm), and pT3:9 (38.3 ± 24.2 mm). The median bCt level was 202 pg/mL (lower/upper quartile: 82/1074 pg/mL). Ultrasound was positive for tumor in 45/50 (92%) patients (20.0 ± 16.0 mm) and negative in 5 patients (3.2 ± 2.2 mm). Overall, 43/50 (86%) patients had positive F-DOPA local scans (20.0 ± 16.4 mm), while 7 (14%) patients were negative (7.7 ± 8.1 mm). Lastly, 21/50 (42%) patients had LN metastasis; 8/21 (38%) patients had positive LNs suspected with ultrasound, and 12/21 (57%) patients had positive LNs suspected with F-DOPA. Tumor and LN sensitivity of ultrasound was 92% and 43%, respectively, and 86% and 57% of F-DOPA-PET-CT, respectively. In 3/50 (6%) patients and 3/50 (6%) patients, mediastinal LN metastasis and distant metastasis, respectively, were diagnosed only by F-DOPA-PET-CT.

Conclusion

Ultrasound and F-DOPA-PET-CT are sensitive for the localization of MTC but not for the presence and location of LN metastasis (limitations: size/number). Only F-DOPA ensures the diagnosis of distant metastasis and influences the extent of LN surgery. Surgical strategy cannot be predicted based on neither ultrasound nor F-DOPA-PET-CT.

INCIDENTAL THYROID NODULES: RACE/ETHNICITY DISPARITIES AND OUTCOMES

OBJECTIVE

Black patients have a significantly lower incidence of well-differentiated thyroid cancer (WDTC) compared to all other race/ethnic groups, while white patients appear to be at greater risk. This study examines incidental thyroid nodules (ITNs) to assess whether racial disparities in WDTC arise from a differential discovery of ITNs-perhaps due to socioeconomic disparities-or reflect true differences in thyroid cancer rates.

METHODS

A retrospective review was performed of all patients who underwent fine-needle aspiration (FNA) of thyroid nodules by our academic medical center's endocrinology division between January 2006 and December 2010. Medical records were reviewed to identify whether the biopsied thyroid nodule was discovered incidentally through nonthyroid-related imaging or identified by palpation.

RESULTS

FNAs were performed on 1,369 total thyroid nodules in 1,141 study patients; 547 (48%) were classified as white, and 593 (52%) were classified as nonwhite. Among this cohort, 36.6% of patients underwent biopsy for an ITN. White patients were 1.6 times more likely to have undergone a biopsy for a nodule that was incidentally identified compared to nonwhites ( P<.0001). Indicators of socioeconomic status (SES) did not have a significant association with ITNs. Within the ITN cohort, 4.9% of nonwhite patients were found to have a thyroid malignancy compared to 12.9% of white patients ( P<.01).

CONCLUSION

The higher incidence of thyroid cancer in white patients appears to be not only due to diagnostic bias, but also to a true difference in cancer prevalence.

ABBREVIATIONS

FNA = fine-needle aspiration; ITN = incidental thyroid nodule; SEER = Surveillance Epidemiology and End Results; SES = socioeconomic status; WDTC = well-differentiated thyroid cancer.

Internal Spreading of Papillary Thyroid Carcinoma: A Case Report and Systemic Review

An 18-year-old female diagnosed finally as PTC with intrathyroid spread was reported, and the diagnosis and surgical treatment of internal spreading of PTC were discussed. One lump was found on the thyroid isthmus by physical examination and B ultrasound, and multiple nodular shadows were found by CT. This patient finally underwent total thyroidectomy with bilateral central node dissection due to multifocal papillary thyroid carcinoma except PTC in the isthmus found in right lobe by intraoperative frozen section. The pathological section showed a major thyroid carcinoma in thyroid isthmus with scattered micropapillary carcinoma around it in the whole thyroid gland. The small lesions are distributed around central lesion in a radial form and the number of small lesions decreases with increased distance from central lesion. PTC with internal spread should be distinguished from multifocal PTC and poorly differentiated PTC in pathology. Thyroid cancerous node had a large diameter; it was likely to have internal spread. Combined imaging before surgery should be valued to diagnose PTC with internal spread. Preoperative CT and intraoperative frozen section are helpful for surgical volume selection of PTC with internal spread.

Hyperintense Thyroid Incidentaloma on Time of Flight Magnetic Resonance Angiography

Background: The purpose of this study was to evaluate the clinical significance of thyroid incidentaloma with hypersignal intensity on the time of flight magnetic resonance (TOF-MR) angiography and correlation with ultrasound (US). Methods: We retrospectively reviewed 3,505 non-contrast TOF-MR angiography performed at our institution between September 2014 and May 2017. Two radiologists correlated the thyroid incidentalomas detected on TOF-MR angiography with US features that were obtained within a three-month interval between MR and US examinations in consensus. Results: The prevalence of hyperintense thyroid nodules incidentally detected by TOF-MR angiography was 1.2% (43/3,505 patients). Among these, 35 people (77.8%) underwent US examinations, and a total of 45 hyperintense thyroid nodules were detected by US studies. Of these 45 nodules, more than 70% were categorized as benign on US exams. Fine needle aspiration was performed on nine nodules according to indications recommended by the Korean Society of Thyroid Radiology. All except one high-suspicion thyroid nodule were confirmed as benign (Bethesda 2) on cytologic examination. The high-suspicion nodule on US showed a nondiagnostic result (Bethesda 1). However, this nodule collapsed after aspiration of thick colloid. Conclusions: Our study demonstrated that the most hyperintense thyroid nodules detected on TOF-MR angiography were benign. Therefore, if a hyperintense incidentaloma is found on TOF-MR angiography, the thyroid nodule is more likely to be benign. We believe that these findings could offer additional information for further clinical management.

Application of Multimodality Imaging Fusion Technology in Diagnosis and Treatment of Malignant Tumors under the Precision Medicine Plan

Objective:

The arrival of precision medicine plan brings new opportunities and challenges for patients undergoing precision diagnosis and treatment of malignant tumors. With the development of medical imaging, information on different modality imaging can be integrated and comprehensively analyzed by imaging fusion system. This review aimed to update the application of multimodality imaging fusion technology in the precise diagnosis and treatment of malignant tumors under the precision medicine plan. We introduced several multimodality imaging fusion technologies and their application to the diagnosis and treatment of malignant tumors in clinical practice.

Date Sources:

The data cited in this review were obtained mainly from the PubMed database from 1996 to 2016, using the keywords of “precision medicine”, “fusion imaging”, “multimodality”, and “tumor diagnosis and treatment”.

Study Selection:

Original articles, clinical practice, reviews, and other relevant literatures published in English were reviewed. Papers focusing on precision medicine, fusion imaging, multimodality, and tumor diagnosis and treatment were selected. Duplicated papers were excluded.

Results:

Multimodality imaging fusion technology plays an important role in tumor diagnosis and treatment under the precision medicine plan, such as accurate location, qualitative diagnosis, tumor staging, treatment plan design, and real-time intraoperative monitoring. Multimodality imaging fusion systems could provide more imaging information of tumors from different dimensions and angles, thereby offing strong technical support for the implementation of precision oncology.

Conclusion:

Under the precision medicine plan, personalized treatment of tumors is a distinct possibility. We believe that multimodality imaging fusion technology will find an increasingly wide application in clinical practice.