5 mCi pretreatment scanning does not cause stunning when the ablative dose is administered within 72 hours.
OBJECTIVE
To determine the stunning effect of a tracer dose of 5 mCi iodine-131.


METHODS
We retrospectively analyzed 145 patients who received the first ablative treatment at our service. Patients were divided according to disease status determined upon post-treatment scanning (101 patients with thyroid remnants and 44 with pulmonary metastases) and whole-body scanning before ablation (performed on 69 individuals). All patients with thyroid remnants were treated with an ablative dose of 100 mCi and those with metastases received 200 mCi.


RESULTS
In patients with remnants only (n= 41) or metastases (n= 28) submitted to diagnostic scanning, uptake was found to be apparently increased in most patients cases (71 and 73%, respectively) 7 days after therapy, while reduced uptake (visual) was not observed in any patient. The efficacy of ablation was similar in the groups submitted or not to diagnostic scanning: 71 and 80% in patients without metastases (p= 0.28), respectively, and 43 and 50% in those with pulmonary involvement (p= 0.64).


CONCLUSIONS
The present results indicate that diagnostic scanning using a 5 mCi iodine-131 dose does not interfere with uptake of the ablative dose or with treatment efficacy when ablation is performed within 72 h.
Rosário
Pedro Weslley S
PW
Department of Thyroid, Santa Casa de Belo Horizonte, MG. pedrorosario@globo.com
Barroso
Alvaro Luís
AL
Rezende
Leonardo L
LL
Padrão
Eduardo Lanza
EL
Maia
Frederico F Ribeiro
FF
Fagundes
Tales A
TA
Purisch
Saulo
S
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes / Q000008:administration & dosage*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary; D008297:Male; D008875:Middle Aged; D018365:Neoplasm, Residual; D011877:Radionuclide Imaging; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D013997:Time Factors; D016896:Treatment Outcome; D051598:Whole Body Imaging
D007457:Iodine Radioisotopes