Observation of Histological Changes in Parathyroid Adenomas Following High Intensity Focused Ultrasound (HIFU) Treatment Procedure

Inclusion Criteria:

* Male or female patient 18 years or older.
* Patients with diagnosed primary hyperparathyroidism (clinical symptoms and/or biochemical disturbances) scheduled for parathyroidectomy.
* One diseased parathyroid gland, visualized by ultrasonography.
* The diseased targeted parathyroid gland accessible for HIFU treatment (anonymised ultrasonographic images to be sent to the sponsor's technical team for validation).
* Normal pretreatment nasofibroscopy.
* Voluntary signed informed consent.

Exclusion Criteria:

* Inaccessibility or high risk of targeting neighbouring structures, as evidenced by:

  * Targeted area located less than 2 mm laterally from the oesophagus or the carotid artery
  * Targeted area located less than 3 mm laterally from the trachea,
  * Significant hyperechoic area with a posterior shadow located less than 10 mm behind the targeted area (behind to be understood as posterior to the targeted area in the direction of the HIFU beam)
* Investigator appreciation of any abnormal blood test that could contraindicate treatment with HIFU (bleeding abnormalities)
* Known spondylitis of the neck vertebrae
* Head and/or neck disease that prevents hyperextension of neck.
* Known history of parathyroid or other neoplasias in the neck region.
* History of neck irradiation
* Patients whose concurrent illnesses, disability, or geographical residence would hamper attendance at required study visit
* Pregnant or lactating woman.
* Female patient of childbearing age if not having a suitable contraception method.
* Patients who have received any investigational drug or device within the last 15 days and/or patients who are currently participating in another clinical trial.