Toward 3D-TRUS image-guided interstitial brachytherapy for cervical cancer

Brachytherapy. 2022 Mar-Apr;21(2):186-192. doi: 10.1016/j.brachy.2021.10.005. Epub 2021 Dec 6.

Abstract

Purpose: To qualitatively and quantitatively analyze needle visibility in combined intracavitary and interstitial cervical cancer brachytherapy on 3D transrectal ultrasound (TRUS) in comparison to gold standard MRI.

Methods and materials: Image acquisition was done with a customized TRUS stepper unit and software (Medcom, Germany; Elekta, Sweden; ACMIT, Austria) followed by an MRI on the same day with the applicator in place. Qualitative assessment was done with following scoring system: 0 = no visibility 1 (= poor), 2 (= fair), 3 (= excellent) discrimination, quantitative assessment was done by measuring the distance between each needle and the tandem two centimeters (cm) above the ring and comparing to the respective measurement on MRI.

Results: Twenty-nine implants and a total of 188 needles (132 straight, 35 oblique, 21 free-hand) were available. Overall, 79% were visible (87% straight, 51% oblique, 76% free-hand). Mean visibility score was 1.4 ± 0.5 for all visible needles. Distance of the visible needles to tandem was mean ± standard deviation (SD) 21.3 millimeters (mm) ± 6.5 mm on MRI and 21.0 mm ± 6.4 mm on TRUS, respectively. Difference between MRI and TRUS was max 14 mm, mean ± SD -0.3 mm ± 2.6 mm. 11% differed more than 3 mm.

Conclusions: Straight needles were better detectable than oblique needles (87% vs. 51%). Detectability was impaired by insufficient rotation of the TRUS probe, poor image quality or anatomic variation. As needles show a rather indistinct signal on TRUS, online detection with a standardized imaging protocol in combination with tracking should be investigated, aiming at the development of real time image guidance and online treatment planning.

Keywords: Cervical cancer; Image guidance; Trus and/or interstitial brachytherapy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Brachytherapy* / methods
  • Female
  • Humans
  • Imaging, Three-Dimensional / methods
  • Magnetic Resonance Imaging / methods
  • Ultrasonography
  • Uterine Cervical Neoplasms* / diagnostic imaging
  • Uterine Cervical Neoplasms* / radiotherapy