title: Outpatient thyroid remnant ablation using repeated low 131-iodine activities (740 MBq/20 mCix2) in patients with low-risk differentiated thyroid cancer.
abstract: BACKGROUND
  In low-risk differentiated thyroid cancer (DTC), postoperative (131)I remnant ablation should employ a minimum effective activity; reports increasingly suggest efficacy of low activities, e.g. 1110 MBq/30 mCi. OBJECTIVES, DESIGN, PATIENTS, AND INTERVENTIONS: We retrospectively studied the ablation capability and diagnostic utility of the Minidose protocol, two 740-MBq/20 mCi outpatient administrations, 6-18 months apart, plus related diagnostic procedures, in 160 consecutive (near-) totally thyroidectomized low-risk DTC (pT1/N0-Nx) patients. Successful ablation comprised negative 740-MBq whole-body scintigraphy with cervical uptake below 0.1%, negative stimulated thyroglobulin (STg) (<1 ng/ml, negative thyroglobulin antibodies), and negative Doppler ultrasonography (performed around Minidose 2).
  
  
  METHODS
  The study took place at a referral center.
  
  
  RESULTS
  Minidose imaging found unsuspected nodal or distant metastases in nine of 160 patients (5.6%). Ablation success rates after one (two) 740-MBq activity (activites) were 75.9% (90.2%) in 145 (132) evaluable imaging-negative patients. Compared with thyroid hormone withdrawal, recombinant human TSH stimulation was associated with higher urinary iodine excretion/creatinine, lower cervical uptake, and more frequent ablation success after the first 740 MBq; success rates no longer differed significantly after both administrations. Patients with STg below 10 ng/ml at Minidose 1 were oftener ablated at Minidose 2 (odds ratio=13.9, 95% confidence interval=2.5-76.4, P<0.003), attaining 92.0% final ablation success after recombinant human TSH preparation, suggesting that one 740-MBq activity should suffice in this subgroup. All 81 evaluable patients with prolonged follow-up (mean 41.8±21.9 months after Minidose 1) had no evidence of disease at the last visit.
  
  
  CONCLUSIONS
  The Minidose outpatient ablation protocol is effective and diagnostically useful in low-risk DTC.
authors.affiliation: Department of Nuclear Medicine, Université René Descartes Sorbonne Paris Cité, Assistance Publique, Assistance Publique Hôpitaux de Paris, Cochin, 27 rue du Faubourg Saint Jacques, 75679 Cedex 14, Paris, France. jerome.clerc@cch.aphp.fr
authors.forename: Jérôme
authors.initials: J
authors.lastname: Clerc
authors.forename: Marie
authors.initials: M
authors.lastname: Bienvenu-Perrard
authors.forename: Caroline Pichard
authors.initials: CP
authors.lastname: de Malleray
authors.forename: Françoise
authors.initials: F
authors.lastname: Dagousset
authors.forename: Thierry
authors.initials: T
authors.lastname: Delbot
authors.forename: Marc
authors.initials: M
authors.lastname: Dreyfuss
authors.forename: Lionel
authors.initials: L
authors.lastname: Groussin
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Marlowe
authors.forename: Françoise Aubène
authors.initials: FA
authors.lastname: Leger
authors.forename: Alain
authors.initials: A
authors.lastname: Chevalier
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000532:radiotherapy*; D000231:Adenocarcinoma, Papillary / Q000532:radiotherapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000553:Ambulatory Care; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000532:radiotherapy*; D016896:Treatment Outcome