The management of differentiated thyroid cancer using 123I for imaging to assess the need for 131I therapy.
BACKGROUND
Follow-up of 131I whole-body scanning after 131I ablation is associated with potential stunning. Previous studies have suggested that, for scanning, 123I is more sensitive than 131I in identifying thyroid tissue, but its specificity when positive is less certain.


OBJECTIVE
The use of 123I as an imaging agent in place of serial 131I imaging has been evaluated in the surveillance and treatment of differentiated thyroid carcinoma.


RESULTS
A total of 186 studies in 136 patients with differentiated thyroid carcinoma were evaluated after total or near total thyroidectomy followed by 131I ablation. In 125 studies 123I scanning was negative and no 131I therapy was given; four patients were positive on 123I scanning but for other reasons no 131I therapy was given. In 48/49 patients a positive 123I scan was followed by positive 131I therapeutic uptake. Only one patient failed to show positive uptake of I when first treated and she subsequently demonstrated uptake on a second therapy.


CONCLUSIONS
High-dose 123I imaging is the correct predictor of the 131I post-therapy scan findings in most cases, at an administered activity that avoids stunning. As a diagnostic agent it is preferable to 131I in differentiated thyroid carcinoma.
Ali
Nidhal
N
Department of Nuclear Medicine, St. Bartholomew's Hospital, London, UK.
Sebastian
Cherry
C
Foley
Rosemary R
RR
Murray
Iain
I
Canizales
Ana L
AL
Jenkins
Paul J
PJ
Drake
William M
WM
Plowman
P Nicholas
PN
Besser
G Michael
GM
Chew
Shern L
SL
Grossman
Ashley B
AB
Monson
John P
JP
Britton
Keith E
KE
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging* / Q000517:prevention & control*; D011379:Prognosis; D011877:Radionuclide Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D016896:Treatment Outcome; D051598:Whole Body Imaging / Q000379:methods*
D007457:Iodine Radioisotopes