title: (124)I PET/CT in Patients with Differentiated Thyroid Cancer: Clinical and Quantitative Image Analysis.
abstract: BACKGROUND
  Although radioactive iodine (RAI) imaging/therapy is one of the earliest applications of theranostics, there remain a number of unresolved clinical questions as to the optimization of diagnostic techniques/protocols and improvements in patient-specific treatment planning strategies. The objectives of this study were to determine the imaging characteristics and clinical feasibility of (124)I positron emission tomography/computed tomography (PET/CT) for the determination of extent of disease and evaluation of RAI kinetics in its physiologic and neoplastic distribution in patients with differentiated thyroid cancer (DTC).
  
  
  METHODS
  The study was designed as a prospective phase II diagnostic trial of patients with confirmed DTC. Following adequate preparation, patients received 2 mCi (124)I in liquid form and sequential whole-body PET/CT imaging was performed at five time points (2-4 h, 24 ± 6 h, 48 ± 6 h, 72 ± 6 h, and 96 ± 6 h post-administration). All patients who had (124)I imaging subsequently underwent RAI treatment with (131)I, with administered activities ranging from 100 to 300 mCi. Post-treatment scans were obtained 5-7 days after RAI treatment. A by-patient and by-lesion analysis of the (124)I images was performed and compared with the post-treatment (131)I scans as well as F-18 FDG PET/CT images. Quantitative image analysis was also performed to determine the total functional volume (mL), activity per functional volume (μCi/mL), and cumulated activity (μCi/h) for remnants, salivary glands, and nodal metastases.
  
  
  RESULTS
  Fifteen patients (6 women; Mage = 57 years; range 29-91 years) were enrolled into the study. Forty-six distinct lesions were identified in these 15 patients on (124)I PET/CT images, with a sensitivity of 92.5%. In addition, (124)I identified 22.5% more foci of RAI-avid lesions compared with the planar (131)I post-treatment scans. This study demonstrates different kinetic profiles for normal thyroid remnants (peaked at 24 h with mono-exponential clearance), salivary glands (peaked at 4 h with bi-exponential clearance), and metastatic lesions (protracted retention), as well as individual variations in functional volumes and thus cumulated activities.
  
  
  CONCLUSIONS
  (124)I PET/CT is a valuable clinical imaging tool/agent, both in determining the extent of disease in the setting of metastatic DTC and in the functional volumetric and kinetic evaluation of target lesions.
authors: 1 Department of Surgical Oncology, Endocrine Surgery, Florida International University Herbert Wertheim College of Medicine, Miami, Florida.
authors: Seza A
authors: SA
authors: Gulec
authors: 2 Department of Radiology, University of Miami Miller School of Medicine, Miami, Florida.|3 Division of Nuclear Medicine, University of Miami Miller School of Medicine, Miami, Florida.
authors: Russ A
authors: RA
authors: Kuker
authors: 2 Department of Radiology, University of Miami Miller School of Medicine, Miami, Florida.
authors: Mohammed
authors: M
authors: Goryawala
authors: 4 Department of Radiology, Elite Imaging Center, Miami, Florida.
authors: Carlos
authors: C
authors: Fernandez
authors: 5 Department of Endocrinology, Thyroid Medical Institute, Miami, Florida.
authors: Rudolfo
authors: R
authors: Perez
authors: 6 Department of Endocrinology, Chen Medical Associates, Miami, Florida.
authors: Alina
authors: A
authors: Khan-Ghany
authors: 6 Department of Endocrinology, Chen Medical Associates, Miami, Florida.
authors: Ana
authors: A
authors: Apaza
authors: 6 Department of Endocrinology, Chen Medical Associates, Miami, Florida.
authors: Evis
authors: E
authors: Harja
authors: 7 Department of Endocrinology, Memorial Health Care System, Hollywood, Florida.
authors: Mack
authors: M
authors: Harrell
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002454:Cell Differentiation; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000008:administration & dosage / Q000493:pharmacokinetics*; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D000072078:Positron Emission Tomography Computed Tomography; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D019275:Radiopharmaceuticals / Q000008:administration & dosage / Q000493:pharmacokinetics*; D012974:Sodium Iodide / Q000008:administration & dosage / Q000493:pharmacokinetics*; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D014018:Tissue Distribution
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D012974:Sodium Iodide