Graves disease (Basedow disease) is an autoimmune form of hyperthyroidism caused by TSH receptor stimulating antibodies (TRAb/TSI). It is characterized by diffuse enlargement of the thyroid gland, diffuse increased vascularity ('thyroid inferno' pattern), and hyperfunction. It is the most common cause of hyperthyroidism (60-80%). It is 5-10 times more common in women and peaks between ages 20-40. Nodules may develop in the setting of Graves — these nodules are usually benign adenomatous nodules but may contain papillary carcinoma in 3-5% of cases. Graves-specific imaging findings are diffuse parenchymal changes, but accompanying nodules should be separately evaluated according to TI-RADS.
Age Range
20-50
Peak Age
35
Gender
Female predominant
Prevalence
Uncommon
In Graves disease, TSH receptor stimulating antibodies (TRAb/TSI) produced by B lymphocytes bind to TSH receptors on thyroid follicular cells, mimicking TSH. This stimulation increases follicular cell proliferation, colloid synthesis, and T3/T4 production — resulting in diffuse thyroid enlargement and hyperthyroidism. Increased metabolic activity and cell proliferation enhance VEGF (vascular endothelial growth factor) release, leading to intense neovascularization. This neovascularization creates the diffuse increased vascularity pattern known as 'thyroid inferno' on Doppler US — intense, chaotic, multidirectional flow signals are seen throughout the entire gland. On scintigraphy, diffuse increased and homogeneous Tc-99m/I-123 uptake is seen because TRAb upregulates NIS expression throughout the entire gland. This differs from patterns in subacute thyroiditis (destructive thyrotoxicosis — low uptake) and toxic adenoma (focal increased uptake).
The 'fire' appearance created by intense, chaotic, multidirectional colored flow signals throughout the entire thyroid gland on color Doppler US. Reflects TRAb-induced massive neovascularization. Highly specific to Graves disease and distinguishing from other causes of hyperthyroidism.
Color Doppler US shows diffuse, markedly increased vascularity throughout the entire thyroid gland — the 'thyroid inferno' pattern. Intense, chaotic, multidirectional colored flow signals almost completely cover the gland surface. Peak systolic velocity (PSV) in inferior thyroid arteries may increase 2-3 fold above normal (>40 cm/s, normal <25 cm/s). Power Doppler more prominently shows increased perfusion. This pattern is highly specific for Graves disease and is distinguishing from subacute thyroiditis (decreased vascularity), toxic adenoma (focal increase), and multinodular goiter (heterogeneous).
Report Sentence
Color Doppler US shows diffuse markedly increased vascularity ('thyroid inferno' pattern) in the thyroid gland, consistent with Graves disease. Inferior thyroid artery PSV: ... cm/s.
B-mode US shows diffuse enlargement of the thyroid gland — both lobes and isthmus are symmetrically expanded. Parenchyma appears diffusely hypoechoic compared to normal thyroid parenchyma, with echogenicity approaching that of strap muscles. Mild heterogeneity may be present but distinct nodularity suggests MNG. Smooth gland surface (not lobulated) is an important finding distinguishing Graves from MNG.
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Thyroid gland is diffusely enlarged with diffusely hypoechoic parenchyma. Consistent with Graves disease when correlated with clinical and laboratory findings.
Tc-99m pertechnetate scintigraphy shows diffuse, homogeneous, and markedly increased uptake in the thyroid gland. Gland borders are clearly delineated with homogeneous high activity throughout all parenchyma. 20-minute Tc-99m uptake is usually >5% (normal 0.3-3%). 24-hour RAIU with I-123 is >40% (often 60-90%). Pyramidal lobe uptake is a finding specific to Graves disease.
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Tc-99m scintigraphy shows diffuse, homogeneous, markedly increased uptake in the thyroid gland, consistent with Graves disease. Pyramidal lobe uptake [present/absent]. 20-min uptake: ...%
I-123 24-hour RAIU (radioactive iodine uptake) is markedly elevated — usually >40%, often 60-90% (normal 10-30%). This elevated uptake is a pathognomonic indicator of stimulatory thyrotoxicosis in Graves disease and clearly differentiates from destructive thyrotoxicosis (subacute thyroiditis, RAIU <5%). The RAIU value is required for I-131 dose calculation in treatment planning.
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I-123 24-hour RAIU measured at ...%, which is markedly elevated; consistent with stimulatory thyrotoxicosis/Graves disease.
Non-contrast CT may show diffuse enlargement and decreased parenchymal density of the thyroid gland. Normal thyroid is 80-120 HU; in Graves, stored iodine decreases as iodine consumption increases, and density may drop to 50-70 HU. Gland borders are smooth, lobulated contour suggests MNG. CT is not routine for Graves diagnosis but is used for evaluating extrathyroidal manifestations (orbit, mediastinum).
Report Sentence
Thyroid gland is diffusely enlarged with decreased parenchymal density (... HU) on CT. Possibility of Graves disease requires clinical correlation.
Criteria
Diffusely enlarged, homogeneous hypoechoic parenchyma. No nodules. Thyroid inferno pattern. Diffuse increased scintigraphic uptake.
Distinct Features
Most common form (70-80%). Homogeneous hypoechoic appearance on US. Treatment: antithyroid drugs, I-131, or surgery. TRAb positive, anti-TPO may be positive.
Criteria
Autonomous functional nodules accompanying Graves disease. Focal hot nodules on a background of diffuse increased uptake on scintigraphy. Prevalence 3-5%.
Distinct Features
Diffuse increased uptake + additional focal hot nodules on scintigraphy. Nodules may persist after I-131 treatment and may require second treatment.
Criteria
Malignant thyroid nodule in the setting of Graves (3-5% rate). Cold nodule on scintigraphy or suspicious TI-RADS 4-5 nodule on US. Papillary carcinoma is the most common type.
Distinct Features
Hypoechoic, microcalcified, irregular-bordered, taller-than-wide nodule on US — requires FNA per TI-RADS. Whether carcinoma behaves more aggressively in the Graves + carcinoma coexistence is debated.
Distinguishing Feature
In subacute thyroiditis vascularity is decreased (increased in Graves — thyroid inferno), focal hypoechoic area is seen (diffuse in Graves) and RAIU is very low (very high in Graves). Both can present with thyrotoxicosis but the mechanism is opposite.
Distinguishing Feature
Hashimoto thyroiditis also shows diffuse hypoechoic parenchyma but vascularity is not as markedly increased as in Graves. Hashimoto usually presents with hypothyroidism (Graves with hyperthyroidism). Micronodular pattern and fibrotic bands are more prominent in Hashimoto. Anti-TPO may be positive in both but TRAb is specific to Graves.
Distinguishing Feature
In toxic MNG, scintigraphy shows heterogeneous uptake (hot + cold nodules); in Graves, there is diffuse, homogeneous increased uptake. In MNG, the gland has lobulated contours (smooth in Graves), nodules are distinct, and vascularity is heterogeneous. TRAb is usually negative in MNG.
Urgency
urgentManagement
medicalBiopsy
Not NeededFollow-up
3-monthGraves disease treatment includes three options: antithyroid drugs (methimazole/propylthiouracil — 12-18 months), radioactive iodine (I-131), or surgery (total/subtotal thyroidectomy). Choice depends on patient preference, age, goiter size, and complications. Antithyroid drugs are first-line (40-60% remission). I-131 is definitive treatment but causes permanent hypothyroidism. Accompanying nodules should be evaluated per ACR TI-RADS, suspicious nodules should be referred for FNA. In Graves ophthalmopathy, there is risk of worsening after I-131 — corticosteroid prophylaxis is needed in active orbitopathy. Thyroid crisis (thyroid storm) is an emergency: high-dose propylthiouracil + beta-blocker + corticosteroid + iodine (Lugol's solution).
Thyroid nodules are detected in 25-30% of Graves disease patients. Nodular malignancy risk in Graves background is reported at 5-15%. Each nodule should be evaluated by TI-RADS and FNA performed on suspicious ones. Graves treatment includes antithyroid drugs, RAI, or surgery.