41. Radioisotope diagnostics of thyroid diseases and parathyroid diseases.

From greek.doctor
  • 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
    • 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
  • 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