Imaging Pearls ❯ Chest ❯ Thyroid Gland
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- “Substernal nodular goiter usually results from simple goiter. Although bilateral glands are often involved, the large lesions are usually located in unilateral gland. Large substernal nodular goiter often causes compression of surrounding structures, secondary hyperthyroidism and malignant changes. Therefore, surgery will be indicated when the diagnosis is confirmed . However, if it is treated with surgery, the operative bleeding risk was high. Most of the cases are operated upon via a cervical or combined cervical-thoracic approach. Substernal goiter resection performed through cervical approach is minimally invasive with less potential complications. The patients don’t require thoracotomy and rehabilitate fast postoperatively.”
Surgical treatment of large substernal thyroid goiter: analysis of 12 patients
Bo Gao et al.
Int J Clin Exp Med. 2013; 6(7): 488–496. - "Substernal goiter refers to the thyroid mass grows along dermal sternum from the neck to the substernal portion, descending below the thoracic inlet. The currently accepted definition of an intrathoracic goiter is a thyroid gland with more than 50% of its mass located below the thoracic inlet. It is characterized by slow progression and a longer course of illness. If the substernal goiter compresses the adjacent esophagus, trachea, nerves and blood vessels, then the corresponding symptoms would occur.”
Surgical treatment of large substernal thyroid goiter: analysis of 12 patients
Bo Gao et al.
Int J Clin Exp Med. 2013; 6(7): 488–496. - "The role of the radiologist in evaluation of substernal thyroid goiters is to provide the surgeon with an anatomic roadmap to guide surgical intervention. The radiologist provides an accurate account of the substernal extent of the mass and describes its impact on the trachea, esophagus, and vascular structures. Imaging the patient with the arms overheard can result in misleading substernal localization of the goiter. Substernal thyroid goiters should be imaged with the patient’s arms by the sides, because this is the position the patient will be in during surgery, and this position most accurately reflects the true anatomic location of the gland.”
Preoperative Imaging of Thyroid Goiter: How Imaging Technique Can Influence Anatomic Appearance and Create a Potential for Inaccurate Interpretation
Derek B. Pollard, Colin W. Weber and Patricia A. Hudgins
American Journal of Neuroradiology May 2005, 26 (5) 1215-1217 - “Surgeons have long been familiar with the impact when a patient with a large thyroid goiter simultaneously raises both arms overhead. Pemberton sign or “thyroid cork” describes the physical manifestation of marked facial plethora resulting from jugular vein compression when the thoracic inlet rises so that it is temporarily filled by a large substernal goiter. Although elevating the patient’s arms and shoulders above the head is desirable to eliminate the beam-hardening artifact from the shoulders, it may also have the adverse consequence of temporarily increasing the apparent descent of a substernal goiter.”
Preoperative Imaging of Thyroid Goiter: How Imaging Technique Can Influence Anatomic Appearance and Create a Potential for Inaccurate Interpretation
Derek B. Pollard, Colin W. Weber and Patricia A. Hudgins
American Journal of Neuroradiology May 2005, 26 (5) 1215-1217
- What is your strategy for an incidental thyroid nodule discovered on a CT scan?
- “There are no definitive guidelines for the management of incidental thyroid lesions on computed tomography (CT). The objectives of our study were to assess the association between CT and ultrasound (US) characteristics of thyroid lesions and identify CT predictors of benignity or malignancy.”
Thyroid Lesions Visualized on CT: Sonographic and Pathologic Correlation.
Lee C et al.
Acad Radiol. 2015 Feb;22(2):203-9 - “The malignancy prevalence of incidental lesions initially detected on CT was 1.6% (2 of 125). Of the 143 patients without pathologic data, 58 (40.6%) were classified as benign and 85 (59.4%) were categorized as indeterminate based on US evaluation. Statistically significant associations were found between CT and US with regard to lesion number, dominant lesion size, lesion consistency/composition, and associated calcifications. No CT characteristics of thyroid lesions predicted malignancy. However, there were statistically significant associations on multivariate analysis between indeterminate/benign nodules and CT characteristics of smaller lesion size, lower mean attenuation, and homogeneous composition.”
Thyroid Lesions Visualized on CT: Sonographic and Pathologic Correlation.
Lee C et al.
Acad Radiol. 2015 Feb;22(2):203-9 - “No CT characteristics of thyroid lesions predicted malignancy. However, there were statistically significant associations on multivariate analysis between indeterminate/benign nodules and CT characteristics of smaller lesion size, lower mean attenuation, and homogeneous composition.”
Thyroid Lesions Visualized on CT: Sonographic and Pathologic Correlation.
Lee C et al.
Acad Radiol. 2015 Feb;22(2):203-9 - “The malignancy prevalence of incidental lesions initially detected on CT was 1.6% (2 of 125). Of the 143 patients without pathologic data, 58 (40.6%) were classified as benign and 85 (59.4%) were categorized as indeterminate based on US evaluation. Statistically significant associations were found between CT and US with regard to lesion number, dominant lesion size, lesion consistency/composition, and associated calcifications.”
Thyroid Lesions Visualized on CT: Sonographic and Pathologic Correlation.
Lee C et al.
Acad Radiol. 2015 Feb;22(2):203-9 - CONCLUSIONS:
“ Recommending sonographic evaluation of all incidentally detected thyroid lesions is likely not the appropriate strategy, given the high prevalence of thyroid incidentalomas, low probability of malignancy, and cost effectiveness of workup. Small, homogeneous, low-attenuation lesions have a high probability of being benign.”
Thyroid Lesions Visualized on CT: Sonographic and Pathologic Correlation.
Lee C et al.
Acad Radiol. 2015 Feb;22(2):203-9 - CT of a Thyroid Nodules: Benign Characteristics
- Under 2 cm
- Homogeneous more likely benign
- Enhancement pattern not helpful
- Presence of calcifications not helpful
- Thyroid Lesions Visualized on CT: Sonographic and Pathologic Correlation.
Lee C et al.
Acad Radiol. 2015 Feb;22(2):203-9 
- “The ITN is one of the most common incidental findings on imaging studies that include the neck. It is defined as a nodule identified by an imaging study that was not previously detected or suspected clinically. There is currently a paucity of guidance from professional organizations on management of ITNs, and high variability in reporting of ITNs by radiologists.”
Managing Incidental Thyroid Nodules Detected on Imaging: White Paper of the ACR Incidental Thyroid Findings Committee
Hoang JK et al.
J Am Coll Radiol 2015;12:143-150 - “Added to the problem of an increased rate of reporting of ITNs, and variability in reporting, is the accessibility of thyroid nodules to biopsy and the low threshold for biopsy. Fine-needle aspiration (FNA) is a very effective and safe test for determining the histology of the ITN. However, unless the cytology result is definitively benign or malignant, patients may embark on a process of further investigations and procedures that may include surveillance, repeat biopsy, and diagnostic surgery. This process results in anxiety and potential morbidity for the patient, and is a cumulatively costly problem for the health care system.”
Managing Incidental Thyroid Nodules Detected on Imaging: White Paper of the ACR Incidental Thyroid Findings Committee
Hoang JK et al.
J Am Coll Radiol 2015;12:143-150 - “ITNs are seen in 20%-67% of ultrasound studies, up to 25% of contrast-enhanced chest CT scans, and 16%-18% of CT and MR scans of the neck.”
Managing Incidental Thyroid Nodules Detected on Imaging: White Paper of the ACR Incidental Thyroid Findings Committee
Hoang JK et al.
J Am Coll Radiol 2015;12:143-150 - “Thyroid cancers <2 cm generally have an indolent course, with a 99.9% 10-year survival rate, and failure to diagnose these cancers is unlikely to affect morbidity and mortality.”
Managing Incidental Thyroid Nodules Detected on Imaging: White Paper of the ACR Incidental Thyroid Findings Committee
Hoang JK et al.
J Am Coll Radiol 2015;12:143-150 - “Although FNA of ITNs carries minimal risk to the patient, the inability of cytology to definitively establish a benign diagnosis in a subset of nonmalignant nodules may expose a substantial number of patients to repeat biopsy or lead to diagnostic surgical removal of benign nodules. Retrospective studies show that 25%-41% of patients who undergo FNA for ITNs proceed to surgery, and 36%-75% of these patients will have benign nodules. The rate of benign results is this high because cytology is inherently limited for the diagnoses of “follicular neoplasm” and “suspicion for follicular neoplasm.”
Managing Incidental Thyroid Nodules Detected on Imaging: White Paper of the ACR Incidental Thyroid Findings Committee
Hoang JK et al.
J Am Coll Radiol 2015;12:143-150 - “Although radiologists fear failure in detecting malignancies, the prognosis for most small, localized papillary cancers is excellent, even without treatment. As previously discussed, Harach et al found that the background rate of subclinical thyroid cancers at autopsy is at least 36%. In clinical studies, an observational trial of 340 patients with untreated papillary microcarcinomas found no cancer deaths over a 10-year period, and new nodal metastases in only 3% of patients.”
Managing Incidental Thyroid Nodules Detected on Imaging: White Paper of the ACR Incidental Thyroid Findings Committee
Hoang JK et al.
J Am Coll Radiol 2015;12:143-150 - “In the general population with normal life expectancy and without suspicious imaging features, patient age and nodule size should determine the need for workup. The Committee recommends further evaluation with ultrasound for patients age <35 years with nodules measuring >1 cm in the axial plane. If the patient is age >35 years, the size cutoff in the axial plane for further evaluation is raised to 1.5 cm. For patients with multiple thyroid nodules, the flowchart in Figure 1 should be applied to the largest thyroid nodule.”
Managing Incidental
Thyroid Nodules Detected on Imaging: White Paper of the ACR Incidental Thyroid Findings Committee Hoang JK et al.
J Am Coll Radiol 2015;12:143-150 - ACR Recommendations for Incidental Thyroid Nodule
- TAKE-HOME POINTS
- In patients age <35 years with an ITN detected on CT, MRI, or extrathyroidal ultrasound, the Committee recommends further evaluation with dedicated thyroid ultrasound if the nodule is ≥ cm and has no suspicious imaging features, and if the patient has normal life expectancy.
- In patients age ≥35 years with an ITN detected on CT, MRI, or extrathyroidal ultrasound, the Committee recommends further evaluation with dedicated thyroid ultrasound if the nodule is !1.5 cm and has no suspicious imaging features, and if the patient has normal life expectancy.
- In patients with focal metabolic activity in the thyroid on 18FDG-PET, the Committee recommends both dedicated thyroid ultrasound and FNA of the PET-avid lesion if the patient has normal life expectancy.
- In patients with focal metabolic activity in the thyroid on other nuclear medicine studies, the Committee recommends dedicated thyroid ultrasound if the patient has normal life expectancy.
Managing Incidental Thyroid Nodules Detected on Imaging: White Paper of the ACR Incidental Thyroid Findings Committee
Hoang JK et al.
J Am Coll Radiol 2015;12:143-150 - Take-Home Points per ACR
In patients age <35 years with an ITN detected on CT, MRI, or extrathyroidal ultrasound, the Committee recommends further evaluation with dedicated thyroid ultrasound if the nodule is ≥1 cm and has no suspicious imaging features, and if the patient has normal life expectancy. - Take-Home Points per ACR
In patients age ≥35 years with an ITN detected on CT, MRI, or extrathyroidal ultrasound, the Committee recommends further evaluation with dedicated thyroid ultrasound if the nodule is ≥1.5 cm and has no suspicious imaging features, and if the patient has normal life expectancy. - Take-Home Points per ACR
- In patients with focal metabolic activity in the thyroid on 18FDG-PET, the Committee recommends both dedicated thyroid ultrasound and FNA of the PET- avid lesion if the patient has normal life expectancy.
- In patients with focal metabolic activity in the thyroid on other nuclear medicine studies, the Committee recommends dedicated thyroid ultrasound if the patient has normal life expectancy.
"There is at least an 11.3% prevalence of malignant or potentially malignant lesions among incidental thyroid abnormalities detected on CT. Patients 35 years or younger who have incidental abnormalities have a significantly greater rate of malignancy. No CT feature reliably distinguishes benign from malignant lesions in the thyroid gland. CT underestimates the number of nodules relative to sonography, which suggests that sonography is a useful adjunctive test after the incidental detection of a thyroid abnormality on CT."
Significance of Incidental Thyroid Lesions Detected on CT: Correlation Among CT, Sonography, and Pathology
Shetty SK et al.
AJR 2006 Nov;187(5):1349-1356- What CT findings of an incidental thyroid nodule are concerning?
- malignant nodules showed nodular or rim calcifications more frequently than benign nodules
- AP/T ratio of greater than 1.0 was more frequent in malignant nodules (anterior-posterior to transverse diameter measurements)
- higher mean attenuation value is more frequent in malignant nodules (>130 HU)
"The prevalence of incidental thyroid lesions in the general population seems to be high—approximately 10% to 40% in ultrasonography studies and 36% to 50% in autopsy series. Most of these lesions are benign; however the risk of malignancy ranges from 1.5% to 17% in incidentally detected lesions."
The Prevalence and Significance of Incidental Thyroid Nodules Identified on Computed TomographyYoon DY et al.J Comput Assist Tomogr 2008;32:810-815"We found at least 9.4% (15/160) prevalence of malignancy among incidental thyroid nodules detected on CT. The further evaluation with US or biopsy should be performed if an ITN shows CT features suggesting malignancy (calcification; AP/T ratio >1.0, or mean attenuation value >130 HU)."
The Prevalence and Significance of Incidental Thyroid Nodules Identified on Computed TomographyYoon DY et al.J Comput Assist Tomogr 2008;32:810-815- How do you manage the incidental thyroid nodule seen on a CT scan of the neck or chest?
- Mention it in the report but do not provide further guidance
- Advise clinical correlation
- Recommend ultrasound in all cases
- Ignore it
- All of the above at different times "Four specific patterns were identified; spongiform configuration, cyst with colloid clot, giraffe pattern and diffuse hyper-echogenicity, which had 100% specificity for benignity. In our series identification of nodules with one of these four patterns could have obviated more than 60% of thyroid biopsies."
Pattern Recognition of Benign Nodules at Ultrasound of the Thyroid: Which Nodules Can Be Left Alone?
Bonavita JA et al
AJR 2009;193:207-213"Recognition of specific morphologic patterns is an accurate method of identifying benign thyroid nodules that do not require cytologic evaluation. Use of this approach may substantially decrease the number of unnecessary biopsy procedures."
Pattern Recognition of Benign Nodules at Ultrasound of the Thyroid: Which Nodules Can Be Left Alone?
Bonavita JA et al
AJR 2009;193:207-213- Thyroid Nodules: Some Facts
- Seen in up to 50% of the population in autopsy series
- Incidence of malignancy in thyroid nodule is 3-7%
- Increased incidence of discovery with modern imaging techniques