Parathyroid Glands: location, condition and value of imaging tests.

Parathyroid Glands: location, condition and value of imaging tests. Poster No.: C-2283 Congress: ECR 2015 Type: Educational Exhibit Authors: E. Elías Cabot, P. Segui, G. D. Tobar Murgueitio; Cordoba/ES Keywords: Hyperplasia / Hypertrophy, Endocrine disorders, Education, Ultrasound, Nuclear medicine conventional, CT, Thyroid / Parathyroids, Head and neck DOI: 10.1594/ecr2015/C-2283 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 29

Learning objectives -To identify usual and unusual locations of parathyroid glands. -To review the various pathological entities related to these glands and the value of the key imaging tests (ultrasound, scintigraphy and CT) Background Primary Hyperparathyroidism is a common endocrine pathology that primarily affects women between 40 and 60 years old. The main imaging tests for the evaluation of this pathology are the ultrasound and the scintigraphy with Tc 99m Sestamibi (MIBI). In some cases a CT can be helpful, especially with glands of ectopic localization. The definitive treatment is surgical: minimally invasive surgery. Secondary Hyperparathyroidism: In secondary hyperparathyroidism, PTH levels are high as a result of chronic renal failure and chronic hypocalcaemia. It is associated with hyperplasia of the parathyroid glands. Imaging tests, mainly the ultrasound, are used to assess the severity of this condition. The main treatment is dialysis. Surgery is rarely required. With regards to the radiological study of pathologies of the parathyroid glands, we answer the following questions: Where should I look for parathyroid glands? How parathyroid adenomas look like? Are parathyroid adenomas always hipoecogenos? What size should they have? Should I necessarily find anything? If there is a nodule, is it necessarily an adenoma? If the nodule is small, could it be a normal parathyroid? Page 2 of 29

What does it mean if there are multiple nodules? What is the value of the MIBI scintigraphy if positive? What is the value if negative? WHERE SHOULD I LOOK FOR PARATHYROID GLANDS? Upper parathyroid glands: posterior or middle/upper portion of the thyroid lobe Inferior parathyroid glands: posterior or inferior to the inferior pole of the thyroid lobe In summary: posterior or inferior to the thyroid lobe (Fig. 1 and 2) Most parathyroid adenomas are located posterior or immediately inferior to the thyroid lobe and medial to the carotid (Fig. 3, 4 and 5) 3% have an ectopic location: (Fig. 12) Retrotracheal, retroesophageal (Fig. 11), mediastinum, carotid sheath, lower neck or intrathyroidal (Fig. 13). WHAT DO PARATHYROID ADENOMAS LOOK LIKE? Oval homogeneous solid mass, hypoechoic to the thyroid gland. Hypervascularized, except when they are small sized or very deep located. The "vascular arch" is a typical finding. It must be distinguished from glands presenting a central hilar vascularity. (Fig. 6) On CT they appear as well-defined nodules usually hyperenhanced in relation to the thyroid gland. ARE PARATHYROID ADENOMAS ALWAYS HYPOECHOGENIC? Occasionally adenomas with atypical appearances are found: cystic, heterogeneous (Fig.7), hyperechogenic (Fig.8) or with calcifications. WHAT SIZE SHOULD THEY HAVE? Average measure between 0.8 and 1.5 cm. Smaller sizes are less frequent: microadenomas (Fig. 9) Macroadenomas: differential diagnosis with carcinoma must be made (Fig.7) SHOULD I NECESSARILY FIND ANYTHING? Page 3 of 29

False negative: - Minimally enlarged adenoma (Fig. 9) - Adjacent lesions in an enlarged or multinodular thyroid (Fig. 10) - Ectopic parathyroid adenoma (Fig. 11, 12 and 13) IF THERE IS A NODULE, IS IT NECESSARILIY AN ADENOMA? False positive: - Cervical Lymph node (Fig. 14 and 15) - Thyroid nodule (Fig. 16) - Anatomical structures (Fig. 17) Prominent blood vessel Esophagus Longus colli muscle IF THE NODULE IS SMALL, COULD IT BE A NORMAL PARATHYROID? Normal parathyroid glands are usually not visualized. The average size is 5x3x1mm, and they are isoechogenic to normal thyroid. (Fig. 18) WHAT DOES IT MEAN IF THERE ARE MUTIPLE NODULES? Multiglandular disease: if more than one gland is enlarged the condition is parathyroid hyperplasia. Anatomopathologically is not possible to distinguish between adenoma and hyperplasia. (Fig. 19 and 20) The concept of "multiple adenoma" is controversial and generally not accepted. WHAT IS THE VALUE OF THE MIBI SCINTIGRAPHY IF POSITIVE? WHAT IS THE VALUE IF NEGATIVE? MIBI Scintigraphy consists of an early stage (10-15 minutes) and a late stage (2-3 hours). Adenomatous/hyperplastic tissue presents uptake of Tc-99m which persists at late stage. It has a sensitivity of 88% similar to the ultrasound to detect solitary parathyroid Page 4 of 29

adenomas. Its sensitivity is slightly higher than ultrasound in parathyroid hyperplasia. (Fig.21). The main advantage over ultrasound is the detection of ectopic glands in mediastinum. FALSE NEGATIVE (Fig. 22): -Multiglandular disease: parathyroid hyperplasia -Some lesions have an early wash-out: uptake in the early stage but not late. FALSE POSITIVE: -The most frequent are thyroid nodules (Fig. 23) (follicular adenomas, colloid nodules, carcinomas ) -Lymph node, remnant thymic, ectopic thyroid tissue... Images for this section: Page 5 of 29

Fig. 1: Parathyroid glands location. Sc: subctuaneous tissue E: esophagus. C: carotid artery Ms: músculo Fig. 2: Parathyroid glands location. Sc: subctuaneous tissue. Ms: músculo Page 6 of 29

Fig. 3: ADENOMA OF THE LEFT INFERIOR PARATHYROID GLAND. Images at the top: cervical ultrasound, axial (panel A) and longitudinal (panel B) scans. Image at the bottom: axial CT image. Lesion was unnoticed on CT. Page 7 of 29

Fig. 4: ADENOMA OF THE LEFT INFERIOR PARATHYROID GLAND. It is located caudal to the inferior pole of the left thyroid lobe. Axial scan (panel A), longitudianl scan (panel B y C) y longitudinal scan with color Doppler imaging ( panel D) Page 8 of 29

Fig. 5: ADENOMA OF THE UPPER RIGHT PARATHYROID GLAND 84-year-old male. Routine analysis Ca 14 mgr/dl and PTH: 200 Ultrasound, axial scan (panel A) and longitudinal scan (panel B): hypoechoic rounded nodule adjacent to the posterior margin of the superior pole in the right thyroid lobe Parathyroid scintigraphy (C) was positive (arrow). The patient had normal ultrasound and scintigraphy done 2 years before. Page 9 of 29

Fig. 6: Normal appearance of parathyroid adenoma on ultrasound Page 10 of 29

Fig. 7: Atypical large size parathyroid adenomas Page 11 of 29

Fig. 8: Atypical parathyroid adenoma. Ultrasound: axial (A) and longitudinal (B) scan. Page 12 of 29

Fig. 9: Parathyroid microadenoma. Ultrasound:Axial (A)and longitudinal (B) scan Page 13 of 29

Fig. 10: False negative: parathyroid adenoma in multinodular goiter Page 14 of 29

Fig. 11: Retroesophageal adenoma Page 15 of 29

Fig. 12: Ectopic adenoma Page 16 of 29

Fig. 13: INTRATHYROIDAL ADENOMA Ultrasound shows a very vascularized and welldefined hypoechogenic solid nodule (mid third of left thyroid lobe) Page 17 of 29

Fig. 14: False positive: lymph node Page 18 of 29

Fig. 15: False positive: adenopathy Page 19 of 29

Fig. 16: FALSE POSITIVE: Thyroid nodule Page 20 of 29

Fig. 17: False positive: normal anatomic estructures Page 21 of 29

Fig. 18: Normal parathyroid gland Page 22 of 29

Fig. 19: Parathyroid Hyperplasia Page 23 of 29

Fig. 20: Parathyroid Hyperplasia Page 24 of 29

Fig. 21: Parathyroid Hyperplasia Page 25 of 29

Fig. 22: Scintigraphic: false negative Page 26 of 29

Fig. 23: Scintigraphic: false positive Page 27 of 29

Findings and procedure details Most parathyroid adenomas are located posterior or immediately inferior to the thyroid lobe and medial to the carotid. 3% have an ectopic location The main imaging test for the evaluation of this pathology are the ultrasound and the scintygraphy with Tc 99m Sestamibi. In some cases a CT can be helpful, especially with glands of ectopic localization. Normal appearance of parathyroid adenoma of ultrasound: Oval homogeneus solid mass,hypoechoic to the thyroid gland and hypervascularized with color doppler. Occasionally adenomas with atypical appearances are found False negative: -Minimally enlarged adenoma -Adjacent lesions in an enlarged or multinodular thyroid -Ectopic parathyroid adenoma False positive: -Cervical Lymph node -Thyroid nodule -Anatomical structures Normal parathyroid glands are usually not visualized Multiple nodules: if more than one gland is enlarged the condition is parthyroid hyperplasia. Anatomopathologically is not possible to distinguish between adenoma and hyperplasia. Page 28 of 29

MIBI Scintigraphy consists of an early stage (10-15 minutes) and a late stage (2-3 hours). Adenomatous/hyperplastic tissue presents uptake of Tc-99m which persists at late stage. It has a sensitivity similar to the ultrasound to detect solitary parathyroid adenomas. Its sensitivity is slightly higher than ultrasound in parathyroid hyperplasia. The main advantage over ultrasound is the detection of ectopic glands in mediastinum. Conclusion Most pathologies related to the parathyroid are diagnosed with the help of an ultrasound or scintigraphy (MIBI), or the combination of both. In some cases a TC can be useful, especially with glands of ectopic location. Personal information References -Vitettta GM, Neri P, Chiecchio A, Cariero A, Cirillo S, Mussetto AB, Codegone A. " Role of ultrasonography in the management of patients with primary hyperparathyroidism: retrospective comparision with tchnetium-99m sestamibi scintigraphy". J Ultrasound. 2014 Jan 31;17(1):1-12 -Nathan A. Johnson, MD, Sally E. Carty, MD, Mitchell E. Tublin, MD. "Parathyroid Imaging". Radiol Clin N Am 49 (2011) 489-509 -Kenneth J Nichols, PhD. Mari B. Tomas, MD. Gene G. Tronco, MD.Josephine N Rini,MD. "Preoperative Parathyroid Scintigraphic Lesion Localization : Accuracy of Various Types of Readings". Radiology; Volume 248 : Number 1 -July 2008. -Willian D. Middleton, MD, Alfred B. Kurtz, MD, Barbara S. Hertzberg, MD. "Ultrasound". Cap. 10: 254-257. 2007 Page 29 of 29