Toxic Adenoma other imaging findings: Difference between revisions

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{{CMG}} ; {{AE}} {{ADG}}
{{CMG}} ; {{AE}} {{ADG}}
==Overview==
==Overview==
[[Radionuclide]] imaging and quantitative [[Radioisotopic labeling|radioisotopic uptake]] studies are always required to establish the diagnosis of toxic adenoma or toxic nodular goiter. [[Radionuclide imaging]] can be performed with radioactive [[iodine-123]] or with [[technetium-99m]]. In patients with [[hyperthyroidism]] caused by a toxic adenoma, there is a characteristic restriction of [[Radionuclides|radionuclide]] uptake to the responsible hyperfunctioning [[nodule]] with suppression of [[Radionuclides|radionuclide]] uptake in the remainder of the [[gland]].
==Other Imaging Findings==
==Other Imaging Findings==
*Radionuclide imaging and quantitative radioisotopic uptake studies are always required to establish the diagnosis of toxic adenoma or toxic nodular goiter  
*[[Radionuclide imaging]] and quantitative [[Radioisotopic labeling|radioisotopic uptake]] studies are always required to establish the diagnosis of [[toxic adenoma]] or toxic nodular goiter.<ref name="pmid4110446">{{cite journal |vauthors=Hurley PJ, Maisey MN, Natarajan TK, Wagner HN |title=A computerized system for rapid evaluation of thyroid function |journal=J. Clin. Endocrinol. Metab. |volume=34 |issue=2 |pages=354–60 |year=1972 |pmid=4110446 |doi=10.1210/jcem-34-2-354 |url=}}</ref>
*Radionuclide imaging can be performed with radioactive iodine-123 ( 123 I) or with technetium-99m ( 99m Tc).  
*[[Radionuclide imaging]] can be performed with [[radioactive]] [[iodine-123]] or with [[technetium-99m]].<ref name="pmid15162989">{{cite journal |vauthors=Smith JR, Oates E |title=Radionuclide imaging of the thyroid gland: patterns, pearls, and pitfalls |journal=Clin Nucl Med |volume=29 |issue=3 |pages=181–93 |year=2004 |pmid=15162989 |doi= |url=}}</ref><ref name="pmid24001133">{{cite journal |vauthors=Bianco AC, Anderson G, Forrest D, Galton VA, Gereben B, Kim BW, Kopp PA, Liao XH, Obregon MJ, Peeters RP, Refetoff S, Sharlin DS, Simonides WS, Weiss RE, Williams GR |title=American Thyroid Association Guide to investigating thyroid hormone economy and action in rodent and cell models |journal=Thyroid |volume=24 |issue=1 |pages=88–168 |year=2014 |pmid=24001133 |pmc=3887458 |doi=10.1089/thy.2013.0109 |url=}}</ref>
*Radionuclide imaging performed with 123 I or 99m Tc-technetium pertechnetate, are trapped by the sodium-iodide symporter in functioning thyroid tissue, although only radioiodine is subsequently organified.
*[[Radionuclide imaging]] performed with [[iodine-123]] or [[technetium-99m]], are trapped by the [[sodium-iodide symporter]] in functioning [[Thyroid gland|thyroid tissue]], although only [[radioiodine]] is subsequently organified.
*In patients with hyperthyroidism caused by a toxic adenoma, there is a characteristic restriction of radionuclide uptake to the responsible hyper functioning nodule with suppression of radionuclide uptake in the remainder of the gland.
*In patients with [[hyperthyroidism]] caused by a toxic adenoma, there is a characteristic restriction of radionuclide uptake to the responsible hyperfunctioning [[nodule]] with suppression of radionuclide uptake in the remainder of the [[gland]].
*In patient with a low serum TSH concentration, not only does the scan appearance support the diagnosis of toxic adenoma, but in almost all cases it also excludes malignancy in the nodule.  
*In a patient with a low serum [[TSH]] concentration, not only does the scan appearance support the diagnosis of toxic adenoma, but in almost all cases it also excludes [[malignancy]] in the [[nodule]].  
*It is important to remember that there is a differential diagnosis for this scan appearance, including congenital hemiagenesis of the thyroid with compensatory hypertrophy of the sole lobe, previous hemithyroidectomy, asymmetrical subacute or autoimmune thyroiditis, or a large hypofunctioning nodule in the contralateral lobe. However, in none of these conditions would a low serum TSH concentration and elevated thyroid hormone levels be expected unless the patient coincidentally had another condition causing thyrotoxicosis. In patients with toxic multinodular goiter, the radionuclide scan shows more than one focal area of increased tracer concentration with suppression of extranodular thyroid tissue (see Fig. 14-2 ). If some thyroid nodules are hypofunctioning (cold), it may be necessary to rule out cancer in them by fine-needle aspiration cytology before defining the optimal plan for treatment of the patient’s hyperthyroidism (see later).
*If some [[thyroid]] [[nodules]] are hypo-functioning, it is necessary to rule out [[cancer]] by [[Fine-needle aspiration|fine-needle aspiration cytology]].
{| class="wikitable"
!Differential for thyrotoxicosis
!Fractional Uptake
of Radioactive Iodine in
 
24 hrs (%)
!Radioactive iodine
Distribution
|-
|[[Graves’ disease]]
|40-95
|Diffuse
([[Homogeneous]] within [[thyroid]])
|-
|[[Toxic Adenoma|Toxic adenoma]]
|20-60
|Restricted to autonomous regions in [[thyroid]]
|-
|[[Subacute thyroiditis]]
|<2
|minimal uptake
|-
|[[Silent thyroiditis]]
|<2
|minimal uptake
|-
|[[Iodine]]-induced [[thyrotoxicosis]]
|<2
|minimal uptake
|-
|[[Thyrotoxicosis factitia|Factitious or]]
[[Thyrotoxicosis factitia|iatrogenic thyrotoxicosis]]
|<2
|minimal uptake
|-
|[[Struma ovarii]]
|<2
|Uptake in [[ovary]]
|-
|[[Follicular carcinoma of the Thyroid|Follicular carcinoma]]
|<2
|Uptake in [[cancer]] [[metastasis]]
|-
|[[Thyroid]]-stimulating hormone–induced [[thyrotoxicosis]]
|30-80
|Diffuse
(Homogeneous within [[thyroid]])
|}
 
==References==
{{reflist|2}}

Latest revision as of 17:24, 19 October 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-in-Chief: Aditya Ganti M.B.B.S. [2]

Overview

Radionuclide imaging and quantitative radioisotopic uptake studies are always required to establish the diagnosis of toxic adenoma or toxic nodular goiter. Radionuclide imaging can be performed with radioactive iodine-123 or with technetium-99m. In patients with hyperthyroidism caused by a toxic adenoma, there is a characteristic restriction of radionuclide uptake to the responsible hyperfunctioning nodule with suppression of radionuclide uptake in the remainder of the gland.

Other Imaging Findings

Differential for thyrotoxicosis Fractional Uptake

of Radioactive Iodine in

24 hrs (%)

Radioactive iodine

Distribution

Graves’ disease 40-95 Diffuse

(Homogeneous within thyroid)

Toxic adenoma 20-60 Restricted to autonomous regions in thyroid
Subacute thyroiditis <2 minimal uptake
Silent thyroiditis <2 minimal uptake
Iodine-induced thyrotoxicosis <2 minimal uptake
Factitious or

iatrogenic thyrotoxicosis

<2 minimal uptake
Struma ovarii <2 Uptake in ovary
Follicular carcinoma <2 Uptake in cancer metastasis
Thyroid-stimulating hormone–induced thyrotoxicosis 30-80 Diffuse

(Homogeneous within thyroid)

References

  1. Hurley PJ, Maisey MN, Natarajan TK, Wagner HN (1972). "A computerized system for rapid evaluation of thyroid function". J. Clin. Endocrinol. Metab. 34 (2): 354–60. doi:10.1210/jcem-34-2-354. PMID 4110446.
  2. Smith JR, Oates E (2004). "Radionuclide imaging of the thyroid gland: patterns, pearls, and pitfalls". Clin Nucl Med. 29 (3): 181–93. PMID 15162989.
  3. Bianco AC, Anderson G, Forrest D, Galton VA, Gereben B, Kim BW, Kopp PA, Liao XH, Obregon MJ, Peeters RP, Refetoff S, Sharlin DS, Simonides WS, Weiss RE, Williams GR (2014). "American Thyroid Association Guide to investigating thyroid hormone economy and action in rodent and cell models". Thyroid. 24 (1): 88–168. doi:10.1089/thy.2013.0109. PMC 3887458. PMID 24001133.