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.