Hyperparathyroidism CT: Difference between revisions
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| colspan="4" |Type B pattern is most common type of pattern (approximately half of lesions). | | colspan="4" style="background: #F0FFFF;" | Type B pattern is most common type of pattern (approximately half of lesions). | ||
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*At least 3 phases are required due to the following reasons: | *At least 3 phases are required due to the following reasons: | ||
Revision as of 14:19, 5 September 2017
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Hyperparathyroidism Microchapters |
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Diagnosis |
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Treatment |
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Case Studies |
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Hyperparathyroidism CT On the Web |
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American Roentgen Ray Society Images of Hyperparathyroidism CT |
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Risk calculators and risk factors for Hyperparathyroidism CT |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Anmol Pitliya, M.B.B.S. M.D.[2]
Overview
Good quality preoperative evaluation favors post operative results. 4-dimentional CT scan is an investigation for preoperative localizing of hyper-functioning parathyroid gland. 4D-CT is significantly more sensitive than sestamibi imaging and ultrasound for precise (quadrant) localization of hyper-functioning parathyroid glands. 4D-CT is required to be performed with three phases including non-contrast, arterial, and delayed phase imaging. 4D-CT provides extremely detailed images of neck in multiple planes and enables the visualization of difference in hyper-functioning parathyroid gland compared with normal parathyroid glands and other structures in the neck on the basis on perfusion characteristics ( rapid uptake and washout). 4D-CT is particularly useful in cases of re-operation. The major disadvantage of 4D-CT is significant radiation exposure associated with scanning the patient multiple times.
CT scan
- 4-Dimentional CT scan is an investigation for preoperative localizing of hyper-functioning parathyroid gland.[1]
- 4D-CT may be used for preoperative localization of hyper-functioning parathyroid glands in hyperparathyroidism. 4D-CT is significantly more sensitive than Tc-99m sestamibi imaging and ultrasound for precise (quadrant) localization of hyper-functioning parathyroid glands.[2]
- The name 4D-CT refers to 3-dimensional CT scanning plus additional dimension of changes observed with respect to time as perfusion of contrast occurs. The principle is similar to CT angiography.
- 4D-CT is required to be performed with three phases:[3]
- Non-contrast phase imaging
- Arterial phase imaging
- Delayed phase imaging
- The characteristic enhancement of parathyroid lesions relative to thyroid tissue peaks at arterial phase. There is washout of contrast material from arterial to delayed phase. Images are lower attenuated in non-contrast enhanced phase.[4]
- The enhancement pattern on 4D-CT scans can be grouped into three types on the basis of relative attenuation of hyper-functioning parathyroid glands relative to thyroid gland.
- Type A pattern:
- On arterial phase, there is higher attenuation of parathyroid lesions than thyroid tissue.
- Type B pattern
- On arterial phase, there is no higher attenuation of parathyroid lesions than thyroid tissue.
- On delayed phase, there is lower attenuation of parathyroid lesions than thyroid tissue.
- Type C pattern:
- On arterial phase, there is no higher attenuation of parathyroid lesions than thyroid tissue.
- On delayed phase, there is no lower attenuation of parathyroid lesions than thyroid tissue.
- Note: Type B pattern is most common type of pattern (approximately half of lesions).
- Type A pattern:
| Type of pattern | Attenuation of parathyroid lesions relative to thyroid tissue | ||
|---|---|---|---|
| Arterial phase | Delayed phase | Non-contrast phase | |
| Type A pattern | Higher | -- | -- |
| Type B pattern | Not higher | Lower | -- |
| Type C pattern | Not higher | Not lower | Higher |
| Type B pattern is most common type of pattern (approximately half of lesions). | |||
- At least 3 phases are required due to the following reasons:
- On arterial phase, only 20 % of parathyroid lesions are higher attenuation than thyroid.
- 22% of adenomas have the similar enhancement to the thyroid on both arterial and delayed phase and could be missed without the non-contrast imaging.
- 4D-CT provides extremely detailed images of neck in multiple planes and enables the visualization of difference in hyper-functioning parathyroid gland compared with normal parathyroid glands and other structures in the neck on the basis on perfusion characteristics ( rapid uptake and washout).
- 4D-CT has a sensitivity of 88% in preoperative lateralizing hyper-functioning parathyroid glands to one side of neck.[5]
- 4D-CT has a sensitivity of 79-88% in preoperative localizing the hyper-functioning parathyroid gland to the correct quadrant of the neck (right inferior, right superior, left inferior, or left superior).[6]
- 4D-CT has a specificity of 75-100% in preoperative localizing the hyper-functioning parathyroid glands.[7]
- 4D-CT enables an improved preoperative planning, particularly in case of re-operation.
- A modified technique of 4D-CT/ultrasound (Mod 4D-CT/US) has a sensitivity of 94% and specificity of 96% for lateralizing the hyperfunctioning parathyroid glands to one side of the neck. Mod 4D-CT/US has a sensitivity of 82% and specificity of 93% for localizing the hyper-functioning parathyroid glands to the correct quadrant of the neck (right inferior, right superior, left inferior, or left superior). Mod 4D-CT/US has a positive predictive value of 92% for single-gland disease and 75% for multi-gland disease. Mod 4D-CT/US has a negative predictive value of 73% for single-gland disease and 92% multi-gland disease.[8]
- The major disadvantage of 4D-CT is significant radiation exposure associated with scanning the patient multiple times.
References
- ↑ Hunter GJ, Schellingerhout D, Vu TH, Perrier ND, Hamberg LM (2012). "Accuracy of four-dimensional CT for the localization of abnormal parathyroid glands in patients with primary hyperparathyroidism". Radiology. 264 (3): 789–95. doi:10.1148/radiol.12110852. PMID 22798226.
- ↑ Rodgers SE, Hunter GJ, Hamberg LM, Schellingerhout D, Doherty DB, Ayers GD; et al. (2006). "Improved preoperative planning for directed parathyroidectomy with 4-dimensional computed tomography". Surgery. 140 (6): 932–40, discussion 940-1. doi:10.1016/j.surg.2006.07.028. PMID 17188140.
- ↑ Bahl, Manisha; Sepahdari, Ali R.; Sosa, Julie A.; Hoang, Jenny K. (2015). "Parathyroid Adenomas and Hyperplasia on Four-dimensional CT Scans: Three Patterns of Enhancement Relative to the Thyroid Gland Justify a Three-Phase Protocol". Radiology. 277 (2): 454–462. doi:10.1148/radiol.2015142393. ISSN 0033-8419.
- ↑ Hoang, Jenny K.; Sung, Won-kyung; Bahl, Manisha; Phillips, C. Douglas (2014). "How to Perform Parathyroid 4D CT: Tips and Traps for Technique and Interpretation". Radiology. 270 (1): 15–24. doi:10.1148/radiol.13122661. ISSN 0033-8419.
- ↑ Eichhorn-Wharry LI, Carlin AM, Talpos GB (2011). "Mild hypercalcemia: an indication to select 4-dimensional computed tomography scan for preoperative localization of parathyroid adenomas". Am J Surg. 201 (3): 334–8, discussion 338. doi:10.1016/j.amjsurg.2010.08.033. PMID 21367374.
- ↑ Griffith B, Chaudhary H, Mahmood G, Carlin AM, Peterson E, Singer M; et al. (2015). "Accuracy of 2-Phase Parathyroid CT for the Preoperative Localization of Parathyroid Adenomas in Primary Hyperparathyroidism". AJNR Am J Neuroradiol. 36 (12): 2373–9. doi:10.3174/ajnr.A4473. PMID 26359149.
- ↑ Beland MD, Mayo-Smith WW, Grand DJ, Machan JT, Monchik JM (2011). "Dynamic MDCT for localization of occult parathyroid adenomas in 26 patients with primary hyperparathyroidism". AJR Am J Roentgenol. 196 (1): 61–5. doi:10.2214/AJR.10.4459. PMID 21178047.
- ↑ Kutler DI, Moquete R, Kazam E, Kuhel WI (2011). "Parathyroid localization with modified 4D-computed tomography and ultrasonography for patients with primary hyperparathyroidism". Laryngoscope. 121 (6): 1219–24. doi:10.1002/lary.21783. PMID 21557243.