Topic : Diagnosis And Treatment Of Thyroid Disorders Using Radioisotopes by :Abdulrahman Moh’d Moh’d Khair Msc in Radiology Najran University Radiology Department

● 12 percent of the adult population suffers from some form of thyroid diseases. ● Nuclear medicine has been successfully used for the diagnosis and treatment of several thyroid disorders. ● Diagnostically, the common thyroid imaging study using radioiodine or technetium-99m pertechnetate and radioiodine uptake study are routinely used in all hospitals for the diagnosis. ● Additionally whole-body imaging study using iodine-131 or iodine-123 is used routinely for thyroid cancer postoperative evaluation and follow-up and for treatment of thyrotixcosis.

● Euthyroidism :- A normal and healthy amount of thyroid hormone. ● Hypothyroidism:- Insufficient of thyroid hormone level in the blood stream. ● Thyrotoxicosis :- Elevation of thyroid hormone level in the blood stream. ●TSH :- Thyroid stimulating hormone. ●T4 :- Levothroxine. ●T3 :-Trii odothyronine. ●MNG:- Multi Nodular Goiter. ●Goiter: enlargement of thyroid gland

Anatomy of the thyroid gland ● The thyroid is normally a bilobed or a butterfly shaped organ with each lobe typically measuring 4–5 cm by 1.5–2.0 cm. the gland weighs 10–25 g. the right side is slightly larger than the left. ● The two lobe connected by small organ called isthmus. ● The thyroid lies superior to the suprasternal notch,and anterior to the trachea

Anatomy The cellular composition of the thyroid gland is diverse, which includes the following: Follicular (epithelial) cells, involved in thyroid hormone synthesis Endothelial cells lining the capillaries that provide the blood supply to the follicles Parafollicular or C cells, Fibroblasts, lymphocytes.

● Physiologically Thyroid is based on iodide involving the following: iodine ingestion, trapping and concentration in the thyroid to produce thyroid hormones. ● The most common thyroid hormones are Levothroxine(T4) or Tetrai odothyronine, Trii odothyronine (T3). Which they are synthesized in the Follicular (epithelial) cells and Parafollicular or C cells involved in the production of calcitonin, a hormone involved in calcium metabolism

%)).1- Graves’ disease – Diffuse Toxic Goiter 2- Toxic MNG- (Plummer’s Disease ). 3- Pituitary Tumors – excess TSH. 4- Toxic Single Adenoma. 5- Metastatic thyroid cancers

Most Symptoms & signs of hyperthyroidism ●Sweating ●Tremor ● Bulging eyes. ●Tachycardia ●Goiter ●weiht loss ●Oligomenorrhea ●Muscle wasting

1.Congenital: a. aplasia, hypoplasia, thyroid ectopy b. defect of hormones’ synthesis and effects 2. Acquired: a. autoimmune thyroiditis b. iodide deficient diet c. thyroid ablation (as a consequence of radiation, surgical interventions etc) 3. Pharmacological: iodide,, methimazole, lithium, newmercazole etc

● Cold Intolerance ●Shortness of breath. ●weight Gain ●fatigue and sleepiness ●Dry and hair loss ●High Cholesterol ●Heavier menorrhea

● Since the thyroid gland traps iodine from the circulation and uses it to synthesize thyroxin (T4) and triiodothyronine (T3). ● Administration of tracer amounts of radioactive iodine will enable imaging of functional thyroid tissue. Also, pertechnetate is trapped by the thyroid and can be used as an iodine analog for thyroid imaging ● Procedures of thyroid scan : first measure the dose(syringe dose) by dosimeter then calculate by gamma camera. ● Then inject the Patient,after 15 or 30 min. will do scan. ● The following procedure should be adopted: (a) Patient position: Supine with neck extended to elevate the thyroid. (b) Timing of imaging: —For 123I: Imaging can be done 3–4 hours after oral administration. Delayed images at 24 hours have lower body background but with a lower count rate. —For 131I: Images are obtained 24 hours post-administration. —For 99mTc-pertechnetate: Images are obtained 15–30 min after intravenous administration «

Projections. ● Anterior view; ● 45° right anterior oblique view; ● 45° left anterior oblique view. ●After finish scan calculate the post syringe to measure the uptake by doing ROI around thyroid, background tissues, presyringe and post syringe.

● Large FOV gamma camera with a pin hole or high resolution parallel hole collimator is preferred to allow multiple views of the thyroid and better resolution of thyroid nodules. ●The row data are transferred to a computer on-line in a 512 × 512 or 256 × 256 matrix, these row data are analyzed by packaged of certain Soft ware.

Dose 1.8–2.2 MBq (45–55 μCi) 3–16 MBq (80–400 μCi) 80–200 MBq (2–5 mCi) Method Oral Intravenou s Timing of imaging 24 hours after administr ation 3–4 hours after administration 15–30 min after administration PropertyI–131I–123Tc-99m pertechnetate Physical half-life8 days13 hours6 hours Photon energy (keV)

Thyroid uptake machine

Solitary cold nodule Anterior Anterior with marker LAORAO

Solitary hot nodule (autonomous) AnteriorAnterior with marker LAO RAO

Typical pattern of Grave’s disease with uniform gland uptake and decreased background activity in the surrounding soft tissue Anterior with markerAnterior LAORAO

Scintigraphic pattern of thyroiditis where poor uptake and lack of delineation of thyroid gland borders are the typical features AnteriorAnterior with marker Tc99m Pertechnetate

● We used Iodine-131 Therapy for Thyroid cancer. or ● Hyperthyroidism.

Treatment for thyroid carcinoma; ● The primary treatment for thyroid carcinoma is thyroidectomy. Following thyroidectomy the Iodine-131 therapy for remnants or metastatic thyroid cancer. ● Therapy dose for Ca. In most centers, is a fixed dose between 1 and 4 GBq (25–100 mCi) of 131I is given. Treatment of Hyperthyroidism: ● The most common form of hyperthyroidism is Graves’ disease, which accounts for 60–90% of all cases of thyrotoxicosis. ● Other causes of thyrotoxicosis include toxic adenoma and toxic multinodular goitre. ● Administration of an ablative dose up to (15 mCi)