1*THERE IS NO RELIABLE METHOD OF DISTINGUISHING A SOLID FROM A CYSTIC LESION USING AN ISOTOPE SCAN ALONE*

2*FINE NEEDLE ASPIRATION SHOULD BE USED TO EVALUATE NON-FUNCTIONING SOLID THYROID LESION*

3*WHENEVER THERE IS A PALPABLE NODULE, IT IS IMPORTANT TO CORRELATE CLINICAL FINDINGS WITH SCAN APPEARANCES, AND CAREFUL PLACING OF MARKERS MAY BE NECESSARY*

4*THERE ARE NO RELIABLE WAYS OF DISTINGUISHING A BENIGN THYROID NODULE FROM A MALIGNANT THYROID NODULE ON A THYROID SCAN. THE APPEARANCE OF TISSUE DISPLACEMENT SHOULD RAISE THE SUSPICION OF CANCER, HOWEVER*

5*APPEARANCE OF DIFFUSE TOXIC GOITER (GRAVE'S DISEASE) AFTER THYROID-ECTOMY MAY BE MISLEADING. THE ISTHMUS IS ALMOST ALWAYS REMOVED AT THYROID SURGERY. THERE MAY BE AN ACTIVE PYRAMIDAL LOBE OR ECTOPIC AREAS OF FUNCTION OUTSIDE THE IMMEDIATE THYROID AREA,THE UPTAKE IS USUALLY HIGH, BUT, BECAUSE OF THE SMALLER VOLUME OF TISSUE, MAY BE IN THE NORMAL RANGE*

6*IF A PATIENT WITH A TOXIC NODULE IS TREATED WITH 131I WHILE TAKING ANTITHYROID DRUGS, THERE WILL BE SOME 131I UPTAKE INTO SUPPRESSED TISSUE AND THE INCIDENCE OF SUBSEQUENT HYPOTHYROIDISM RISES FROM NEARLY ZERO TO 20-30%. THYROID SCANNING BEFORE 131I TREATMENT IS THEREFORE ADVISABLE*

7*THE HIGH IODINE CONTENT OF AMIODARONE MAY INDUCE THYROTOXICOSIS*

8*THYROTOXICOSIS MAY PERSIST AFTER AMIODARONE IS DISCONTINUED*

9*ULTRASENSITIVE TSH ESTIMATION SHOULD BE USED TO ASSESS THE SIGNIFICANCE OF A FUNCTIONING NODULE OR NODULES SCAN ON A MULTINODULAR GOITER. SUPPRESSION OF ULTRASENSITIVE TSH WILL CONFIRM AUTONOMOUS FUNCTION*

10*SOLITARY 'COLD' NODULES HAVE A PROBABILITY OF MALIGNANCY OF ABOUT 10%)*

11*DIFFERENTIATED THYROID CANCER DOSE NOT ACCUMULATE 131I AT NORMAL TSH STIMULATION*

12*LEVELS GREATER THAN 30mU/LITER OF TSH MUST BE SHOWN TO BE CERTAIN THAT A POTENTIALLY FUNCTIONING TUMOUR IS NOT MISSED*

13*131I IS THE OPTIMAL ISOTOPE FOR DEMONSTRATING SMALL AMOUNTS OF RESIDUAL TISSUE*

14*AT THE TIME OF THE FIRST SCAN AFTER SURGERY, IT IS NOT POSSIBLE TO DISTINGUISH NORMAL FROM MALIGNANT THYROID TISSUE*

15*AFTER A THERAPEUTIC DOSE OF 131I, ANY RESIDUAL UPTAKE AFTER MORE THAN SIX MONTHS IS LIKELY TO REPRESENT RESIDUAL CANCER*

16*REPLACEMENT RATHER THAN DISPLACEMENT IS A FEATURE OF THYROID CANCER*

17*THYROID TUMOURS DO NOT TAKE UP TRACER UNTIL AFTER ABLATION OF THE THYROID GLAND, WHEN THE TSH HAS RISEN*

18*MICROSCOPIC LUNG METASTASES ARE OFTEN SEEN WITH 131I WHEN THE CHEST X-RAY IS CLEAR; THEY WILL RESPOND WELL TO 131I THERAPY*

19*THALLIUM-201 IS USEFUL ADJUNCT TO 131I IMAGING IN THE FOLLOW-UP OF PATIENTS WITH THYROID CANCER AS THYROXINE REPLACEMENT NEED NOT BE DISCONTINUED PRIOR TO IMAGING*

20*LARGE, DOMINANT 'COLD' NODULE IN A MULTINODULAR GLAND MAY BE MALIGNANT*

21*MEDULLARY CARCINOMA MAY BE FAMILIAL*

22*MEDULLARY CARCINOMA OF THE THYROID MAY BE BILATERAL, AND MULTIFOCAL*

23*THE COMBINATION OF AN ULTRASOUND SCAN AND A 99mTc SCAN IS ESSENTIAL FOR DETERMINING SUBSEQUENT MANAGEMENT IN PATIENTS WITH SOLITARY THYROID NODULES*