Hypothesis: Intraoperative use of near infrared fluorescent imaging technology and detection of Methylene Blue fluorescence will improve outcomes following thyroid and parathyroid surgery.

Aims: The aims of this phase of the study are to determine the feasibility of using near infrared fluorescent technology in the detection of parathyroid tissue and its differentiation from adjacent soft tissue during surgery on parathyroid glands.

Objectives of the phase I study:

1. To familiarise surgical teams with the intraoperative use of the 'Fluobeam(TM)' device (Fluoptics).
2. To understand the patterns (onset, intensity and duration) of fluorescent staining of normal parathyroid glands, thyroid glands and other soft tissue structures encountered during parathyroidectomy.

Further research:

This will be followed by a phase II study during which fluorescent imaging will be used in conjunction with intraoperative incremental dose of IV methylene blue in both thyroid and parathyroid surgery. Phase II will enable us to develop a protocol for the use of a minimum possible dose of MB for the identification of parathyroid glands. This will then be tested in the pilot phase of a randomized clinical trial.

As above

Inclusion Criteria:

• all patients undergoing parathyroid surgery

Exclusion Criteria:

• patients undergoing re-do procedures
• patients unable to give adequate informed consent
• patients with a history of intolerance or sensitivity to MB
• patients with G6PD deficiency
• patients on serotonin reuptake inhibitors and patients undergoing thoracic exploration
• either alone or in combination with a neck exploration.