title: Role of Tc-99m pertechnetate for remnant scintigraphy post-thyroidectomy.
abstract: OBJECTIVE
  Current surgical techniques in patients with differentiated thyroid cancer can leave little or no remnant tissue. Coupled with favorable prognostic factors, this subgroup of patients might not require radioablative remnant ablation with Iodine-131 (I-131). Postoperative scanning may help to identify this subgroup, however low dose I-131 can lead to stunning and suboptimal response to ablative therapy. Iodine-123 (I-123) can be used but is expensive and supply can be limited. We investigate technetium-99m pertechnetate (pertechnetate) as a potential alternative for remnant scintigraphy post-thyroidectomy.
  
  
  METHODS
  Seventy consecutive post-total-thyroidectomy patients were evaluated retrospectively. Preablative pertechnetate scans of the thyroid bed were viewed blindly then directly compared with postablative I-131 scans.
  
  
  RESULTS
  For patients with unequivocally positive pertechnetate uptake, the sensitivity was 81% (patients), 61% (sites), and the PPV was high (100% patients, 95% sites). In patients with either definite or equivocal pertechnetate uptake, the sensitivity was 90% (patients), 68% (sites), and the PPV was also high (100% patients, 81% sites).
  
  
  CONCLUSIONS
  Pertechnetate had reasonable correlation with postablative I-131 scans with a moderately high sensitivity and a very high PPV. A positive pertechnetate scan is therefore sufficient to guide progression to I-131 ablation in most patients. When the scan is equivocal or negative, diagnostic imaging with radioiodine may be required. Pertechnetate scintigraphy may be of particular benefit if it is considered desirable to avoid I-131 in post-thyroidectomy remnant imaging.
authors: Department of Nuclear Medicine, Royal North Shore Hospital, Sydney, Australia. s_h_kueh@yahoo.com
authors: Sherman S H
authors: SS
authors: Kueh
authors: Paul J
authors: PJ
authors: Roach
authors: Geoffrey P
authors: GP
authors: Schembri
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D013670:Sodium Pertechnetate Tc 99m; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery*; D013965:Thyroidectomy; D055815:Young Adult
chemical_list: D013670:Sodium Pertechnetate Tc 99m