Recombinant human thyroid-stimulating hormone versus thyroid hormone withdrawal in 124I-PET/CT based dosimetry for 131I therapy of metastatic differentiated thyroid cancer.

MedStar author(s):
Citation: Journal of Nuclear Medicine. 58(7):1146-1154, 2017 JulPMID: 28104741Institution: MedStar Washington Hospital CenterDepartment: Medicine/Nuclear MedicineForm of publication: Journal ArticleMedline article type(s): Journal ArticleSubject headings: *Iodine Radioisotopes/tu [Therapeutic Use] | *Positron Emission Tomography Computed Tomography/mt [Methods] | *Thyroid Neoplasms/rt [Radiotherapy] | *Thyroid Neoplasms/sc [Secondary] | *Thyrotropin/ad [Administration & Dosage] | *Whole-Body Counting/mt [Methods] | Absorption, Radiation | Adult | Humans | Male | Middle Aged | Premedication/mt [Methods] | Radiopharmaceuticals/tu [Therapeutic Use] | Radiotherapy Dosage | Recombinant Proteins/ad [Administration & Dosage] | Thyroid Neoplasms/dg [Diagnostic Imaging] | Treatment OutcomeYear: 2017Local holdings: Available online from MWHC library: 1964 - present, Available in print through MWHC library: 1999 - 2006ISSN:
  • 0161-5505
Name of journal: Journal of nuclear medicine : official publication, Society of Nuclear MedicineAbstract: CONCLUSION: The results suggest a high patient variability in the overall absorbed dose to the normal organs per MBq of <sup>131</sup>I administered, between the two TSH stimulation methods. The tumor to dose-limiting-organ (bone marrow) absorbed dose ratio, i.e. the therapeutic index was higher in the THW-aided compared to rhTSH-aided administrations. Additional comparison for tumor and normal organ absorbed dose in patients prepared using both methods is needed before definitive conclusions may be drawn regarding rhTSH versus THW patient preparation methods for <sup>131</sup>I therapy of metastatic DTC.Copyright � 2017 by the Society of Nuclear Medicine and Molecular Imaging, Inc.METHODS: Four DTC patients at MedStar Washington Hospital Center were first prepared using the rhTSH method and imaged by <sup>124</sup>I-PET/CT at 2, 24, 48, 72 and 96 hrs post-administration of approximately 30-63 MBq <sup>124</sup>I. After 5-8 weeks, the same patients were prepared using the THW method and imaged as before. The <sup>124</sup>I-PET/CT images acquired as part of a prospective study were used to perform retrospective dosimetric calculations for <sup>131</sup>I therapy for the normal organs using the dosimetry package 3D-RD. The Ds from <sup>131</sup>I for lungs, liver, heart, kidneys and bone marrow were obtained for each study (rhTSH and THW). A total of 22 lesions in three patients were identified. The contours were drawn on each PET image of each study. Time-integrated activity coefficients were calculated and used as input in OLINDA/EXM sphere dose calculator to obtain the absorbed dose to tumors.PURPOSE: Patients with metastatic differentiated thyroid cancer (DTC) may be prepared using either thyroid stimulating hormone withdrawal (THW) or recombinant human thyroid-stimulating hormone (rhTSH) injections prior to <sup>131</sup>I administration for treatment. The objective of this study was to compare the absorbed dose (D) to the critical organs and tumors determined by <sup>124</sup>I-Positron Emission Tomography/Computed Tomography (PET/CT) based dosimetry for <sup>131</sup>I therapy of metastatic DTC when the same patient was prepared with and imaged after both THW and rhTSH injections.RESULTS: The THW-to-rhTSH organ absorbed dose ratio averaged over five organs for the first three patients was 1.5, 2.5 and 0.64, respectively, and averaged over three organs for the fourth patient was 1.1. The absorbed dose per unit administered activity to the bone marrow was 0.13, 0.086, 0.33 and 0.068 mGy/MBq following rhTSH, and 0.11, 0.14, 0.22 and 0.080 mGy/MBq following THW for each patient, respectively. With the exception of three lesions of one patient, the D per unit administered activity of <sup>131</sup>I was higher in the THW study compared to the rhTSH study. The ratio of the average tumor D after stimulation by THW compared to stimulation by rhTSH injections was 3.9, 27 and 1.4, for Pt1, Pt2 and Pt3, respectively. The ratio of mean tumor to bone marrow absorbed dose per unit administered activity of <sup>131</sup>I, after THW and rhTSH was: 232 and 62 (Pt1); 12 and 0.78 (Pt2); 22 and 11 (Pt3), respectively.All authors: Atkins F, Garcia C, Hobbs RF, Huang K, Plyku D, Sgouros G, Van Nostrand DFiscal year: FY2017Digital Object Identifier: Date added to catalog: 2017-05-06
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Item type Current library Collection Call number Status Date due Barcode
Journal Article MedStar Authors Catalog Article 28104741 Available 28104741

Available online from MWHC library: 1964 - present, Available in print through MWHC library: 1999 - 2006

CONCLUSION: The results suggest a high patient variability in the overall absorbed dose to the normal organs per MBq of <sup>131</sup>I administered, between the two TSH stimulation methods. The tumor to dose-limiting-organ (bone marrow) absorbed dose ratio, i.e. the therapeutic index was higher in the THW-aided compared to rhTSH-aided administrations. Additional comparison for tumor and normal organ absorbed dose in patients prepared using both methods is needed before definitive conclusions may be drawn regarding rhTSH versus THW patient preparation methods for <sup>131</sup>I therapy of metastatic DTC.

Copyright � 2017 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

METHODS: Four DTC patients at MedStar Washington Hospital Center were first prepared using the rhTSH method and imaged by <sup>124</sup>I-PET/CT at 2, 24, 48, 72 and 96 hrs post-administration of approximately 30-63 MBq <sup>124</sup>I. After 5-8 weeks, the same patients were prepared using the THW method and imaged as before. The <sup>124</sup>I-PET/CT images acquired as part of a prospective study were used to perform retrospective dosimetric calculations for <sup>131</sup>I therapy for the normal organs using the dosimetry package 3D-RD. The Ds from <sup>131</sup>I for lungs, liver, heart, kidneys and bone marrow were obtained for each study (rhTSH and THW). A total of 22 lesions in three patients were identified. The contours were drawn on each PET image of each study. Time-integrated activity coefficients were calculated and used as input in OLINDA/EXM sphere dose calculator to obtain the absorbed dose to tumors.

PURPOSE: Patients with metastatic differentiated thyroid cancer (DTC) may be prepared using either thyroid stimulating hormone withdrawal (THW) or recombinant human thyroid-stimulating hormone (rhTSH) injections prior to <sup>131</sup>I administration for treatment. The objective of this study was to compare the absorbed dose (D) to the critical organs and tumors determined by <sup>124</sup>I-Positron Emission Tomography/Computed Tomography (PET/CT) based dosimetry for <sup>131</sup>I therapy of metastatic DTC when the same patient was prepared with and imaged after both THW and rhTSH injections.

RESULTS: The THW-to-rhTSH organ absorbed dose ratio averaged over five organs for the first three patients was 1.5, 2.5 and 0.64, respectively, and averaged over three organs for the fourth patient was 1.1. The absorbed dose per unit administered activity to the bone marrow was 0.13, 0.086, 0.33 and 0.068 mGy/MBq following rhTSH, and 0.11, 0.14, 0.22 and 0.080 mGy/MBq following THW for each patient, respectively. With the exception of three lesions of one patient, the D per unit administered activity of <sup>131</sup>I was higher in the THW study compared to the rhTSH study. The ratio of the average tumor D after stimulation by THW compared to stimulation by rhTSH injections was 3.9, 27 and 1.4, for Pt1, Pt2 and Pt3, respectively. The ratio of mean tumor to bone marrow absorbed dose per unit administered activity of <sup>131</sup>I, after THW and rhTSH was: 232 and 62 (Pt1); 12 and 0.78 (Pt2); 22 and 11 (Pt3), respectively.

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