Table of Contents
Northern Lincolnshire and Goole NHS Foundation Trust - Nuclear Medicine
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| SOP Code | Title | Review Date |
|---|---|---|
| REF006 | Parathyroid Localisation Imaging | 2028-01-14 |
| Authorised By | Authorising Role | Authorisation Signature (only on master paper copy) | Date Authorised |
|---|---|---|---|
| Prof G Avery | ARSAC Licence Holder | 2025-01-14 |
REF006 - Parathyroid Localisation Imaging
See REF000 - Referring to Nuclear Medicine (NLAG) for details on how to refer.
Description
Parathyroid scintigraphy is used in the pre-operative localisation of hyperfunctioning parathyroid glands. Normally functioning parathyroid glands are unable to be visualised on nuclear medicine imaging.
The preferred imaging technique is subtraction imaging using Tc99m labelled MIBI and Iodine-123 (I123-Sodium iodide). Tc99m-MIBI localises in parathyroid and thyroid tissue, I123-sodium iodine accumulates in thyroid tissue. Subtraction of the I123 image from the Tc99m images, allows localisation of the abnormal parathyroid glands. In some cases, I123 imaging cannot be used because the patient is taking thyroxine or anti-thyroid medications which cannot be withdrawn for the required period of time. In these cases Tc99m-MIBI imaging can be used alone. Differential washout of MIBI from the thyroid and parathyroid glands allows delayed imaging to be used to identify parathyroid tissue. This technique is generally inferior to the subtraction technique and so is only used when subtraction imaging is not feasible.
| ARSAC Licence Holders |
|---|
| Prof Ged Avery |
| Dr Najeeb Ahmed |
| Radiopharmaceutical | CT Component of SPECT/CT | |
|---|---|---|
| Typical Radiation Dose (mSv) | 6.7-12.8 | 1.1 |
Staff Entitled to Refer
- Referrals will only be accepted from Endocrinologists, ENT/Thyroid surgeons or Renal Physicians as per the Trust’s “Pathway of Parathyroid Surgery and Management of Thyroid Nodule” agreed 29th April 2014.[1]
Supplementary Drugs
- Sodium chloride for parenteral use (0.9% w/v).
Dual Isotope Subtraction Technique
Contraindications
| Patient Demographics | Pregnancy |
|---|---|
| Medication | See Patient Preparation Section below. |
Patient Preparation
The drugs listed below may interfere with the study.
| Drug | Recommendation |
|---|---|
| Anti-thyroid drugs (e.g. carbimazole, methimazole or propylthiouracil) | Patients will be told to stop taking these for 1 week prior to the scan. Please indicate if this is not acceptable. |
| Synthetic Thyroid Hormones (T4, T3) | T4 needs to be withdrawn for 4 weeks prior to the scan. T3 needs to be withdrawn for 2 weeks. Thyrogen stimulation can be used (for 2 days prior to the study) in place of withdrawing thyroid hormones. Alternatively, a MIBI parathyroid washout study can be performed but this often performs less well than a dual isotope I123/MIBI subtraction study. Please indicate your preference |
| Iodine based contrast agents | Avoid for 8 weeks prior to the scan. Alternatively, a MIBI parathyroid washout study can be performed but this often performs less well than a dual isotope I123/MIBI subtraction study. Please indicate your preference |
| Medications, preparations or antiseptics containing Iodine (e.g. vitamin and mineral supplements, kelp, Lugol's solution, potassium iodide, and expectorants) | Must be stopped for 4 weeks prior to the scan. Alternatively, a MIBI parathyroid washout study can be performed but this often performs less well than a dual isotope I123/MIBI subtraction study. Please indicate your preference |
| Amiodarone | Must be stopped for 3-6 months if the subtraction technique is to be used. Alternatively, a MIBI parathyroid washout study can be performed but this often performs less well than a dual isotope I123/MIBI subtraction study. Please indicate your preference |
| Vitamin D analogues Calcimimetics | If safe to do so, withdraw for 2 weeks. Please indicate on the referral if the patient is taking them and whether to stop them. By default, we will not ask the patient to stop these. |
| Calcium channel blockers | The evidence for stopping these is weak. However, please note on the referral if the patient is taking them |
The patient will also be asked to follow a low iodine diet for 2 weeks prior to the scan.
Clinical Indications
References
