Impact of MRI-based postimplant dosimetric assessment in prostate brachytherapy using contrast-enhanced T1-weighted images

Toshio Ohashi, Tetsuo Momma, Shoji Yamashita, Katsumi Nagatsuma, Kunimitsu Kanai, Kazuhito Kitagawa, Shinichi Takahashi, Takashi Hanada, Atsunori Yorozu, Naoyuki Shigematsu

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Purpose: To compare contrast-enhanced T1-weighted (CE-T1WI) magnetic resonance imaging (MRI) with computed tomography (CT) for postimplant dosimetry and seed recognition in prostate brachytherapy. Methods and Materials: A total of 245 patients who received 125I prostate brachytherapy with or without external beam radiotherapy were enrolled. For postimplant analysis, CT and MRI scans were obtained at 1 month after seed implantation. For MRI-based dosimetry, T2-weighted images were fused with the CE-T1WI; the prostate was delineated on the T2-weighted images, and the seed detection was performed manually on the CE-T1WI. In CT-based dosimetry, the seed detection was essentially performed automatically. The dosimetric results obtained by MRI-based and CT-based dosimetry were compared. Results: The mean prostate D90 (the minimum dose received by 90% of the prostate volume) estimated by MRI-based and CT-based dosimetry were 113% and 115%, respectively, with no significant difference. The mean prostate V100 (the percent volume of the postimplant prostate receiving 100% of the prescribed dose) estimated by MRI-based and CT-based dosimetry were 95.2% and 95.8%, respectively, again with no significant difference. The mean prostate V150 (the percent volume of the postimplant prostate receiving 150% of the prescribed dose) estimated by MRI-based and CT-based dosimetry were 52.8% and 57.0%, respectively (p<0.01). In all of the 35 patients (14%) in whom the MRI-based V150 were at least 10% lower than the CT-based results, the seed detection by CT-based dosimetry was overestimated in highly seed-clustered areas or in the areas close to calcifications because of reconstruction artifacts in CT images. Conclusions: MRI-based dosimetry using CE-T1WI appears to be acceptable. Our results suggest that MRI-based dosimetry is a practical method for estimation of the higher dose distribution, especially if seeds are clustered together or when they are close to calcifications.

Original languageEnglish
Pages (from-to)468-475
Number of pages8
JournalBrachytherapy
Volume11
Issue number6
DOIs
Publication statusPublished - 2012 Nov

Fingerprint

Brachytherapy
Prostate
Tomography
Magnetic Resonance Imaging
Seeds
Artifacts
Radiotherapy

Keywords

  • Brachytherapy
  • Dosimetry
  • MRI
  • Postimplant
  • Prostate cancer

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging

Cite this

Impact of MRI-based postimplant dosimetric assessment in prostate brachytherapy using contrast-enhanced T1-weighted images. / Ohashi, Toshio; Momma, Tetsuo; Yamashita, Shoji; Nagatsuma, Katsumi; Kanai, Kunimitsu; Kitagawa, Kazuhito; Takahashi, Shinichi; Hanada, Takashi; Yorozu, Atsunori; Shigematsu, Naoyuki.

In: Brachytherapy, Vol. 11, No. 6, 11.2012, p. 468-475.

Research output: Contribution to journalArticle

Ohashi, Toshio ; Momma, Tetsuo ; Yamashita, Shoji ; Nagatsuma, Katsumi ; Kanai, Kunimitsu ; Kitagawa, Kazuhito ; Takahashi, Shinichi ; Hanada, Takashi ; Yorozu, Atsunori ; Shigematsu, Naoyuki. / Impact of MRI-based postimplant dosimetric assessment in prostate brachytherapy using contrast-enhanced T1-weighted images. In: Brachytherapy. 2012 ; Vol. 11, No. 6. pp. 468-475.
@article{bb206d21f7434bacbd1dbdbaec441f7f,
title = "Impact of MRI-based postimplant dosimetric assessment in prostate brachytherapy using contrast-enhanced T1-weighted images",
abstract = "Purpose: To compare contrast-enhanced T1-weighted (CE-T1WI) magnetic resonance imaging (MRI) with computed tomography (CT) for postimplant dosimetry and seed recognition in prostate brachytherapy. Methods and Materials: A total of 245 patients who received 125I prostate brachytherapy with or without external beam radiotherapy were enrolled. For postimplant analysis, CT and MRI scans were obtained at 1 month after seed implantation. For MRI-based dosimetry, T2-weighted images were fused with the CE-T1WI; the prostate was delineated on the T2-weighted images, and the seed detection was performed manually on the CE-T1WI. In CT-based dosimetry, the seed detection was essentially performed automatically. The dosimetric results obtained by MRI-based and CT-based dosimetry were compared. Results: The mean prostate D90 (the minimum dose received by 90{\%} of the prostate volume) estimated by MRI-based and CT-based dosimetry were 113{\%} and 115{\%}, respectively, with no significant difference. The mean prostate V100 (the percent volume of the postimplant prostate receiving 100{\%} of the prescribed dose) estimated by MRI-based and CT-based dosimetry were 95.2{\%} and 95.8{\%}, respectively, again with no significant difference. The mean prostate V150 (the percent volume of the postimplant prostate receiving 150{\%} of the prescribed dose) estimated by MRI-based and CT-based dosimetry were 52.8{\%} and 57.0{\%}, respectively (p<0.01). In all of the 35 patients (14{\%}) in whom the MRI-based V150 were at least 10{\%} lower than the CT-based results, the seed detection by CT-based dosimetry was overestimated in highly seed-clustered areas or in the areas close to calcifications because of reconstruction artifacts in CT images. Conclusions: MRI-based dosimetry using CE-T1WI appears to be acceptable. Our results suggest that MRI-based dosimetry is a practical method for estimation of the higher dose distribution, especially if seeds are clustered together or when they are close to calcifications.",
keywords = "Brachytherapy, Dosimetry, MRI, Postimplant, Prostate cancer",
author = "Toshio Ohashi and Tetsuo Momma and Shoji Yamashita and Katsumi Nagatsuma and Kunimitsu Kanai and Kazuhito Kitagawa and Shinichi Takahashi and Takashi Hanada and Atsunori Yorozu and Naoyuki Shigematsu",
year = "2012",
month = "11",
doi = "10.1016/j.brachy.2011.12.010",
language = "English",
volume = "11",
pages = "468--475",
journal = "Brachytherapy",
issn = "1538-4721",
publisher = "Elsevier Inc.",
number = "6",

}

TY - JOUR

T1 - Impact of MRI-based postimplant dosimetric assessment in prostate brachytherapy using contrast-enhanced T1-weighted images

AU - Ohashi, Toshio

AU - Momma, Tetsuo

AU - Yamashita, Shoji

AU - Nagatsuma, Katsumi

AU - Kanai, Kunimitsu

AU - Kitagawa, Kazuhito

AU - Takahashi, Shinichi

AU - Hanada, Takashi

AU - Yorozu, Atsunori

AU - Shigematsu, Naoyuki

PY - 2012/11

Y1 - 2012/11

N2 - Purpose: To compare contrast-enhanced T1-weighted (CE-T1WI) magnetic resonance imaging (MRI) with computed tomography (CT) for postimplant dosimetry and seed recognition in prostate brachytherapy. Methods and Materials: A total of 245 patients who received 125I prostate brachytherapy with or without external beam radiotherapy were enrolled. For postimplant analysis, CT and MRI scans were obtained at 1 month after seed implantation. For MRI-based dosimetry, T2-weighted images were fused with the CE-T1WI; the prostate was delineated on the T2-weighted images, and the seed detection was performed manually on the CE-T1WI. In CT-based dosimetry, the seed detection was essentially performed automatically. The dosimetric results obtained by MRI-based and CT-based dosimetry were compared. Results: The mean prostate D90 (the minimum dose received by 90% of the prostate volume) estimated by MRI-based and CT-based dosimetry were 113% and 115%, respectively, with no significant difference. The mean prostate V100 (the percent volume of the postimplant prostate receiving 100% of the prescribed dose) estimated by MRI-based and CT-based dosimetry were 95.2% and 95.8%, respectively, again with no significant difference. The mean prostate V150 (the percent volume of the postimplant prostate receiving 150% of the prescribed dose) estimated by MRI-based and CT-based dosimetry were 52.8% and 57.0%, respectively (p<0.01). In all of the 35 patients (14%) in whom the MRI-based V150 were at least 10% lower than the CT-based results, the seed detection by CT-based dosimetry was overestimated in highly seed-clustered areas or in the areas close to calcifications because of reconstruction artifacts in CT images. Conclusions: MRI-based dosimetry using CE-T1WI appears to be acceptable. Our results suggest that MRI-based dosimetry is a practical method for estimation of the higher dose distribution, especially if seeds are clustered together or when they are close to calcifications.

AB - Purpose: To compare contrast-enhanced T1-weighted (CE-T1WI) magnetic resonance imaging (MRI) with computed tomography (CT) for postimplant dosimetry and seed recognition in prostate brachytherapy. Methods and Materials: A total of 245 patients who received 125I prostate brachytherapy with or without external beam radiotherapy were enrolled. For postimplant analysis, CT and MRI scans were obtained at 1 month after seed implantation. For MRI-based dosimetry, T2-weighted images were fused with the CE-T1WI; the prostate was delineated on the T2-weighted images, and the seed detection was performed manually on the CE-T1WI. In CT-based dosimetry, the seed detection was essentially performed automatically. The dosimetric results obtained by MRI-based and CT-based dosimetry were compared. Results: The mean prostate D90 (the minimum dose received by 90% of the prostate volume) estimated by MRI-based and CT-based dosimetry were 113% and 115%, respectively, with no significant difference. The mean prostate V100 (the percent volume of the postimplant prostate receiving 100% of the prescribed dose) estimated by MRI-based and CT-based dosimetry were 95.2% and 95.8%, respectively, again with no significant difference. The mean prostate V150 (the percent volume of the postimplant prostate receiving 150% of the prescribed dose) estimated by MRI-based and CT-based dosimetry were 52.8% and 57.0%, respectively (p<0.01). In all of the 35 patients (14%) in whom the MRI-based V150 were at least 10% lower than the CT-based results, the seed detection by CT-based dosimetry was overestimated in highly seed-clustered areas or in the areas close to calcifications because of reconstruction artifacts in CT images. Conclusions: MRI-based dosimetry using CE-T1WI appears to be acceptable. Our results suggest that MRI-based dosimetry is a practical method for estimation of the higher dose distribution, especially if seeds are clustered together or when they are close to calcifications.

KW - Brachytherapy

KW - Dosimetry

KW - MRI

KW - Postimplant

KW - Prostate cancer

UR - http://www.scopus.com/inward/record.url?scp=84868099341&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84868099341&partnerID=8YFLogxK

U2 - 10.1016/j.brachy.2011.12.010

DO - 10.1016/j.brachy.2011.12.010

M3 - Article

C2 - 22330102

AN - SCOPUS:84868099341

VL - 11

SP - 468

EP - 475

JO - Brachytherapy

JF - Brachytherapy

SN - 1538-4721

IS - 6

ER -