Multi-modality parathyroid imaging: A shifting paradigm

Figure 1  Diagrammatic representation of location of eutopic (yellow) and ectopic (red) parathyroid glands.

Figure 2 Left inferior parathyroid adenoma. A: High resolution ultrasound image of the neck in the transverse plane demonstrates a well-circumscribed homogenously hypoechoic ovoid lesion located at the lower pole of the left lobe of thyroid gland; B: Colour Doppler shows a big feeding vessel, likely from the inferior thyroid artery (arrow) supplying the lesion.

Figure 3 In a patient with MEN-1 syndrome. A-F: Ultrasound neck images show multiple (3) parathyroid adenoma in the right superior and left superior and inferior parathyroid glands respectively.

Figure 4 Contrast-enhanced ultrasound in parathyroid adenoma. A-C: A 33-year-old female with raised parathormone levels (87 IU) was assessed using contrast enhanced ultrasound. A circumscribed lesion at the lower pole of the left lobe of thyroid gland was found consistent with parathyroid adenoma, demonstrating early peripheral enhancement with central washout.

Figure 5 Imaging features of parathyroid adenomas on four-dimensional computed tomography. CT: Computed tomography.

Figure 6 Right superior adenoma: Four-dimensional computed tomography. A: Non-contrast computed tomography shows a small oval hypodense lesion which shows B: Intense enhancement on the arterial phase; C: Washout on the venous phase consistent with right superior parathyroid adenoma; D: Coronal image and E: Coronal maximum intensity projection image in the arterial phase better demonstrate the lesion with the feeding vessel (black arrow).

Figure 7 Left inferior parathyroid adenoma. In a patient with raised parathormone levels (290 IU), grey scale ultrasound A: and colour doppler flow imaging; B and C: Showed a hypoechoic lesion with vascularity just below the left lobe of the; D: 4-dimensional computed tomography showed the lesion to be hypodense on noncontrast computer tomography; E: Hyperenhancing with central necrosis on arterial phase; F: Washout on the venous phase; G: Coronal image better demonstrates the lesion.

Figure 8 Ectopic parathyroid adenoma in the anterior mediastinum. A: 4-dimensional computed tomography done in the 12-year-old female with hyperparathyroidism showed a well-defined lesion in the anterior mediastinum just behind the sternum which was hypodense on non-contrast computed tomography; B: intense arterial enhancement; C: washout on the venous phase; D: Multiplanar reformatted coronal; E: sagittal images in the arterial phase show the lesion better; F: Oblique sagittal maximum intensity projection image shows the feeding vessel (black arrow); G: Sternotomy followed by thymectomy was done and the thymus opened - the adenoma can be seen within the thymic parenchyma as pointed by the forceps.

Figure 9 Ectopic parathyroid adenoma in the anterior mediastinum. A: Computed tomography in a 45-year-old male patient showed a well-defined ovoid lesion in the prevascular space just posterior to the sternal notch and anterior to the inferior thyroid vessels appearing hypodense on the non-contrast phase; B: Showing intense enhancement on the arterial phase; C: washout in the venous phase; D: Coronal maximum intensity projection image demonstrates the inferior thyroid artery supplying the lesion (feeding vessel - black arrows); E: Fluoro-choline positron emission tomography shows a small tracer avid lesion in ectopic location which correlates with the computed tomography images.

Figure 10  Ectopic Parathyroid Adenoma in the Supraclavicular fossa. A: Grey scale ultrasound of the neck on a 49-year-old male patient, with history of bilateral renal stones and elevated parathormone reveals a hypoechoic lesion in the right supraclavicular location; B: On color doppler, internal vascularity was detected; C: 4-dimensional computed tomography showed a lesion with arterial enhancement; D: Washout seen on the venous phase; E: Coronal reformatted image better depicts the ectopic parathyroid adenoma in the right supraclavicular fossa.

Figure 11  Intrathyroidal parathyroid adenoma. In a patient with raised parathormone (208 IU), A: Color doppler ultrasound of the neck showed a circumscribed solid hypoechoic lesion within the left lobe of thyroid gland; B: 4-dimensional computed tomography revealed the lesion to be hypodense as compared to thyroid tissue on non-contrast; C: showed intense arterial hyperenhancement; D: Washout on the venous phase, consistent with the diagnosis of intra-thyroid parathyroid adenoma; E and F: Coronal (E) and Sagittal maximum intensity projection images better depict the lesions with vascular pedicle (black arrow) seen supplying the lesion (F); G: Single photon emission computed tomography image showing a thyroid nodule which is mildly tracer avid; H: Left hemithyroidectomy was done and the cut open section confirmed the presence of the tumor.

Figure 12  Right superior parathyroid adenoma. A 50-year-old female with raised parathormone levels (96 IU) was examined using duplex ultrasound for parathyroid glands. A: Grey scale sonography in the transverse and longitudinal plane showed a well circumscribed lesion posterior to the right lobe of thyroid gland and separated from it by a clear fat plane; B: Colour doppler image shows a feeding vessel. Corroborative magnetic resonance imaging axial images show a subcentimetric lesion (arrows) posterior to the middle third of the right lobe of thyroid gland which is C: T1 hypointense; D: T2 hyperintense; E: Coronal T2w image better demonstrates the lesion; F: Correlative single photon emission computed tomography component of MIBI scan showing tracer avid lesion at the superior pole of the right lobe of thyroid; G: Image of the resected adenoma weighing 1.05 g.

Figure 13  Parathyroid carcinoma. A 62-year-old male patient with recurrent hyperparathyroidism (previously operated parathyroid carcinoma), 4-dimensional computed tomography done showed few hypodense lesions with ill-defined margins near the lower pole of the left lobe of thyroid gland which showed, A: arterial enhancement however; B: No washout on the venous phase - atypical contrast kinetics for parathyroid adenoma; C: Coronal image better demonstrates the lesion. Surgical exploration and histopathological examination revealed parathyroid carcinoma recurrence.