Hyperparathyroidism CT
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American Roentgen Ray Society Images of Hyperparathyroidism CT |
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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 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).
- {| class="wikitable"
- Type A pattern:
! rowspan="2" |Type of pattern ! colspan="3" |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 |- | colspan="4" |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.[4]
- 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).[5]
- 4D-CT has a specificity of 75-100% in preoperative localizing the hyper-functioning parathyroid glands.[6]
- 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.[7]
- 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.
- ↑ 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.