41. Radioisotope diagnostics of thyroid diseases and parathyroid diseases.
- Thyroid
- Modalities
- Thyroid scintigraphy (thyroid scan)
- SPECT/CT
- 18F-FDG PET
- For thyroid carcinoma metastases which don’t take up iodine or 99mTc-pertechnetate
- Thyroid scintigraphy
- Radiopharmaceuticals used
- 99mTc-pertechnetate
- Most common
- Iodine-123
- Iodine-131
- 99mTc-pertechnetate
- Radiopharmaceuticals used
- Findings
- Hot nodule (increased isotope uptake compared to surrounding thyroid)
- Multiple -> toxic goitre
- Single
- Thyroid carcinoma
- Autonomous adenoma
- Cold nodule (decreased isotope uptake compared to surrounding thyroid)
- Adenoma
- Colloid goitre
- Cyst
- Diffuse increased uptake -> Hyperthyroidism
- Diffuse decreased uptake -> Hypothyroidism
- Hot nodule (increased isotope uptake compared to surrounding thyroid)
- Modalities
- Parathyroid scintigraphy
- Used to localize hyperfunctioning parathyroid tissue in case of hyperthyroidism
- There are no specific radiotracers for parathyroid tissue, so special modalies must be used
- Modalities
- Double-tracer parathyroid scintigraphy
- 2 tracers (99mTc-MIBI and 99mTc-pertechnetate)
- Digital subtraction is used to visualize the hyperfuncitoning parathyroid tissue
- Dual-phase parathyroid scintigraphy
- 1 tracer (99mTc-MIBI)
- 2 phases
- First – 10 minutes after injection
- Second – 2 hours after injection
- SPECT/CT
- Double-tracer parathyroid scintigraphy