Accuracy and variability of high-dose-rate prostate brachytherapy needle tip localization using live two-dimensional and sagittally reconstructed three-dimensional ultrasound

To measure the accuracy and variability of manual high-dose-rate (HDR) prostate brachytherapy (BT) needle tip localization using sagittally reconstructed three-dimensional (3D) transrectal ultrasound (TRUS) augmented with live two-dimensional (2D) sagittal TRUS.

Ten prostate cancer patients underwent HDR-BT during which the sagittally assisted sagittally reconstructed (SASR) segmentation technique was completed in parallel with commercially available sagittally assisted axially reconstructed (SAAR) TRUS for comparison. The SASR technique makes use of live 2D ultrasound intraoperatively and allows needle tip updates using the final 3D image in the absence of image artifacts. These updates were repeated offline twice by two separate users. Needle end-length measurements were used to calculate insertion depth errors (IDEs) for each technique.

Images of 147 needles were analyzed. For the SASR technique, both users were confident in tip positions on the final 3D image within 3 mm for 52% of needles, so these tip positions were updated. For the remaining 48% of needles, the tip positions from the live 2D images were used. This SASR technique enabled the localization of all needles with IDEs within ±3 mm for 84% of needles and IDE range of [-6.2 mm, 5.9 mm], compared with 57% and [-8.1 mm, 7.7 mm] when using the commercially available SAAR technique.

The SASR technique mitigates the impact of 3D TRUS image artifacts on HDR-BT needle tip localization by incorporating live 2D sagittal TRUS intraoperatively and provides a statistically significant reduction in IDE variance compared with the routine SAAR technique.

Brachytherapy. 2017 Jul 29 [Epub ahead of print]

William Thomas Hrinivich, Douglas A Hoover, Kathleen Surry, Chandima Edirisinghe, Vikram Velker, Glenn Bauman, David D'Souza, Aaron Fenster, Eugene Wong

Department of Medical Biophysics, Western University, London, ON, Canada; Robarts Imaging Research Lab, Western University, London, ON, Canada. Electronic address: ., Department of Medical Biophysics, Western University, London, ON, Canada; Department of Oncology, Western University, London, ON, Canada; London Regional Cancer Program, London, ON, Canada., Robarts Imaging Research Lab, Western University, London, ON, Canada., Department of Oncology, Western University, London, ON, Canada; London Regional Cancer Program, London, ON, Canada., Department of Medical Biophysics, Western University, London, ON, Canada; Department of Oncology, Western University, London, ON, Canada; Department of Physics and Astronomy, Western University, London, ON, Canada; Robarts Imaging Research Lab, Western University, London, ON, Canada., Department of Medical Biophysics, Western University, London, ON, Canada; Department of Oncology, Western University, London, ON, Canada; Department of Physics and Astronomy, Western University, London, ON, Canada; London Regional Cancer Program, London, ON, Canada.