title: Prognostic impact of average iodine density assessed by dual-energy spectral imaging for predicting lung tumor recurrence after stereotactic body radiotherapy.
abstract: The purpose of this study was to investigate the prognostic significance of average iodine density as assessed by dual-energy computed tomography (DE-CT) for lung tumors treated with stereotactic body radiotherapy (SBRT). From March 2011 to August 2014, 93 medically inoperable patients with 74 primary lung cancers and 19 lung metastases underwent DE-CT prior to SBRT of a total dose of 45-60 Gy in 5-10 fractions. Of these 93 patients, nine patients had two lung tumors. Thus, 102 lung tumors were included in this study. DE-CT was performed for pretreatment evaluation. Regions of interest were set for the entire tumor, and average iodine density was obtained using a dedicated imaging software and evaluated with regard to local control. The median follow-up period was 23.4 months (range, 1.5-54.5 months). The median value of the average iodine density was 1.86 mg/cm(3) (range, 0.40-9.27 mg/cm(3)). Two-year local control rates for the high and low average iodine density groups divided by the median value of the average iodine density were 96.9% and 75.7% (P = 0.006), respectively. Tumors with lower average iodine density showed a worse prognosis, possibly reflecting a hypoxic cell population in the tumor. The average iodine density exhibited a significant impact on local control. Our preliminary results indicate that iodine density evaluated using dual-energy spectral CT may be a useful, noninvasive and quantitative assessment of radio-resistance caused by presumably hypoxic cell populations in tumors.
authors.affiliation: Department of Radiology and Radiation Oncology, Graduate School of Medicine, Hirosaki University, 5 Zaifu-cho, 036-8562 Hirosaki, Aomori, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Aoki
authors.affiliation: Department of Radiation Oncology, Southern Tohoku Proton Therapy Center, 7-172 Yatsuyamada, 963-8052 Koriyama, Fukushima, Japan.
authors.forename: Katsumi
authors.initials: K
authors.lastname: Hirose
authors.affiliation: Department of Radiology and Radiation Oncology, Graduate School of Medicine, Hirosaki University, 5 Zaifu-cho, 036-8562 Hirosaki, Aomori, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Sato
authors.affiliation: Department of Radiology and Radiation Oncology, Graduate School of Medicine, Hirosaki University, 5 Zaifu-cho, 036-8562 Hirosaki, Aomori, Japan.
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Akimoto
authors.affiliation: Department of Radiology and Radiation Oncology, Graduate School of Medicine, Hirosaki University, 5 Zaifu-cho, 036-8562 Hirosaki, Aomori, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Kawaguchi
authors.affiliation: Department of Radiology and Radiation Oncology, Graduate School of Medicine, Hirosaki University, 5 Zaifu-cho, 036-8562 Hirosaki, Aomori, Japan.
authors.forename: Yoshiomi
authors.initials: Y
authors.lastname: Hatayama
authors.affiliation: Department of Radiology and Radiation Oncology, Graduate School of Medicine, Hirosaki University, 5 Zaifu-cho, 036-8562 Hirosaki, Aomori, Japan.
authors.forename: Ichitaro
authors.initials: I
authors.lastname: Fujioka
authors.affiliation: Department of Radiology and Radiation Oncology, Graduate School of Medicine, Hirosaki University, 5 Zaifu-cho, 036-8562 Hirosaki, Aomori, Japan.
authors.forename: Mitsuki
authors.initials: M
authors.lastname: Tanaka
authors.affiliation: Department of Radiology and Radiation Oncology, Graduate School of Medicine, Hirosaki University, 5 Zaifu-cho, 036-8562 Hirosaki, Aomori, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Ono
authors.affiliation: Department of Radiology and Radiation Oncology, Graduate School of Medicine, Hirosaki University, 5 Zaifu-cho, 036-8562 Hirosaki, Aomori, Japan y-takai@hirosaki-u.ac.jp.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Takai
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007455:Iodine / Q000737:chemistry*; D053208:Kaplan-Meier Estimate; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000000981:diagnostic imaging; D011379:Prognosis; D015900:Radiography, Dual-Energy Scanned Projection; D016634:Radiosurgery; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D007455:Iodine
keywords: dual-energy CT; iodine density; lung cancer; oligometastases; stereotactic body radiotherapy
references.citation: Neuroradiology. 1976;11(1):23-8
references.pmid: 934469
references.citation: Med Phys. 2011 Mar;38(3):1178-88
references.pmid: 21520830
references.citation: Radiology. 2011 Apr;259(1):257-62
references.pmid: 21330561
references.citation: Int J Radiat Oncol Biol Phys. 2011 Aug 1;80(5):1343-9
references.pmid: 20708849
references.citation: Future Oncol. 2014 May;10(7):1299-310
references.pmid: 24947266
references.citation: JAMA. 2010 Mar 17;303(11):1070-6
references.pmid: 20233825
references.citation: Asian Pac J Cancer Prev. 2013;14(6):3613-8
references.pmid: 23886154
references.citation: Radiat Med. 2007 Jul;25(6):289-94
references.pmid: 17634882
references.citation: Radiology. 2009 May;251(2):422-8
references.pmid: 19276321
references.citation: Radiother Oncol. 2010 Jan;94(1):1-11
references.pmid: 20074823
references.citation: AJR Am J Roentgenol. 2012 Nov;199(5 Suppl):S98-S105
references.pmid: 23097174
references.citation: Phys Med Biol. 1976 Sep;21(5):733-44
references.pmid: 967922
references.citation: Int J Radiat Oncol Biol Phys. 2008 Oct 1;72(2):398-403
references.pmid: 18374506
references.citation: J Radiat Res. 2014 Sep;55(5):917-23
references.pmid: 24829253
references.citation: Cancer Biol Ther. 2011 Apr 15;11(8):714-23
references.pmid: 21389772
references.citation: Acad Radiol. 2011 Jun;18(6):682-9
references.pmid: 21393031
references.citation: Int J Radiat Oncol Biol Phys. 2001 Nov 1;51(3):666-70
references.pmid: 11597807
references.citation: Radiology. 2004 Oct;233(1):191-9
references.pmid: 15304661
references.citation: Eur Radiol. 2006 Feb;16(2):256-68
references.pmid: 16341833
references.citation: Cancer. 2012 Apr 15;118(8):2078-84
references.pmid: 22009495
references.citation: Diagn Interv Radiol. 2011 Sep;17 (3):181-94
references.pmid: 20945292
references.citation: Int J Radiat Oncol Biol Phys. 2004 Nov 15;60(4):1241-56
references.pmid: 15519797
references.citation: Jpn J Cancer Res. 1986 Sep;77(9):908-15
references.pmid: 3095287
references.citation: Pancreatology. 2006;6(1-2):77-85
references.pmid: 16327283
references.citation: Int J Radiat Oncol Biol Phys. 2011 Dec 1;81(5):1352-8
references.pmid: 20638194
references.citation: Radiat Oncol. 2010 Sep 17;5:81
references.pmid: 20849623