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Accuracy of gross tumour volume delineation with [68Ga]-PSMA-PET compared to histopathology for high-risk prostate cancer

Zarei, Maryam ; Wallsten, Elin ; Grefve, Josefine ; Söderkvist, Karin ; Gunnlaugsson, Adalsteinn LU ; Sandgren, Kristina ; Jonsson, Joakim ; Lindberg, Angsana Keeratijarut ; Nilsson, Erik and Bergh, Anders , et al. (2024) In Acta Oncologica 63. p.503-510
Abstract

Background: The delineation of intraprostatic lesions is vital for correct delivery of focal radiotherapy boost in patients with prostate cancer (PC). Errors in the delineation could translate into reduced tumour control and potentially increase the side effects. The purpose of this study is to compare PET-based delineation methods with histopathology. Materials and methods: The study population consisted of 15 patients with confirmed high-risk PC intended for prostatectomy. [68Ga]-PSMA-PET/MR was performed prior to surgery. Prostate lesions identified in histopathology were transferred to the in vivo [68Ga]-PSMA-PET/MR coordinate system. Four radiation oncologists manually delineated intraprostatic lesions based... (More)

Background: The delineation of intraprostatic lesions is vital for correct delivery of focal radiotherapy boost in patients with prostate cancer (PC). Errors in the delineation could translate into reduced tumour control and potentially increase the side effects. The purpose of this study is to compare PET-based delineation methods with histopathology. Materials and methods: The study population consisted of 15 patients with confirmed high-risk PC intended for prostatectomy. [68Ga]-PSMA-PET/MR was performed prior to surgery. Prostate lesions identified in histopathology were transferred to the in vivo [68Ga]-PSMA-PET/MR coordinate system. Four radiation oncologists manually delineated intraprostatic lesions based on PET data. Various semi-automatic segmentation methods were employed, including absolute and relative thresholds, adaptive threshold, and multi-level Otsu threshold. Results: The gross tumour volumes (GTVs) delineated by the oncologists showed a moderate level of interobserver agreement with Dice similarity coefficient (DSC) of 0.68. In comparison with histopathology, manual delineations exhibited the highest median DSC and the lowest false discovery rate (FDR) among all approaches. Among semi-automatic approaches, GTVs generated using standardized uptake value (SUV) thresholds above 4 (SUV > 4) demonstrated the highest median DSC (0.41), with 0.51 median lesion coverage ratio, FDR of 0.66 and the 95th percentile of the Hausdorff distance (HD95%) of 8.22 mm. Interpretation: Manual delineations showed a moderate level of interobserver agreement. Compared to histopathology, manual delineations and SUV > 4 exhibited the highest DSC and the lowest HD95% values. The methods that resulted in a high lesion coverage were associated with a large overestimation of the size of the lesions.

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publishing date
type
Contribution to journal
publication status
published
subject
keywords
histopathology, Prostate cancer, PSMA-PET, semi-automatic segmentation
in
Acta Oncologica
volume
63
pages
8 pages
publisher
Taylor & Francis
external identifiers
  • scopus:85197008510
  • pmid:38912830
ISSN
0284-186X
DOI
10.2340/1651-226X.2024.39041
language
English
LU publication?
yes
id
4102673a-6771-412c-b688-0cc8ed8ed40f
date added to LUP
2024-10-04 10:52:28
date last changed
2024-10-04 10:53:12
@article{4102673a-6771-412c-b688-0cc8ed8ed40f,
  abstract     = {{<p>Background: The delineation of intraprostatic lesions is vital for correct delivery of focal radiotherapy boost in patients with prostate cancer (PC). Errors in the delineation could translate into reduced tumour control and potentially increase the side effects. The purpose of this study is to compare PET-based delineation methods with histopathology. Materials and methods: The study population consisted of 15 patients with confirmed high-risk PC intended for prostatectomy. [<sup>68</sup>Ga]-PSMA-PET/MR was performed prior to surgery. Prostate lesions identified in histopathology were transferred to the in vivo [<sup>68</sup>Ga]-PSMA-PET/MR coordinate system. Four radiation oncologists manually delineated intraprostatic lesions based on PET data. Various semi-automatic segmentation methods were employed, including absolute and relative thresholds, adaptive threshold, and multi-level Otsu threshold. Results: The gross tumour volumes (GTVs) delineated by the oncologists showed a moderate level of interobserver agreement with Dice similarity coefficient (DSC) of 0.68. In comparison with histopathology, manual delineations exhibited the highest median DSC and the lowest false discovery rate (FDR) among all approaches. Among semi-automatic approaches, GTVs generated using standardized uptake value (SUV) thresholds above 4 (SUV &gt; 4) demonstrated the highest median DSC (0.41), with 0.51 median lesion coverage ratio, FDR of 0.66 and the 95th percentile of the Hausdorff distance (HD95%) of 8.22 mm. Interpretation: Manual delineations showed a moderate level of interobserver agreement. Compared to histopathology, manual delineations and SUV &gt; 4 exhibited the highest DSC and the lowest HD95% values. The methods that resulted in a high lesion coverage were associated with a large overestimation of the size of the lesions.</p>}},
  author       = {{Zarei, Maryam and Wallsten, Elin and Grefve, Josefine and Söderkvist, Karin and Gunnlaugsson, Adalsteinn and Sandgren, Kristina and Jonsson, Joakim and Lindberg, Angsana Keeratijarut and Nilsson, Erik and Bergh, Anders and Zackrisson, Björn and Moreau, Mathieu and Karlsson, Camilla Thellenberg and Olsson, Lars E. and Widmark, Anders and Riklund, Katrine and Blomqvist, Lennart and Loegager, Vibeke Berg and Axelsson, Jan and Strandberg, Sara N. and Nyholm, Tufve}},
  issn         = {{0284-186X}},
  keywords     = {{histopathology; Prostate cancer; PSMA-PET; semi-automatic segmentation}},
  language     = {{eng}},
  pages        = {{503--510}},
  publisher    = {{Taylor & Francis}},
  series       = {{Acta Oncologica}},
  title        = {{Accuracy of gross tumour volume delineation with [68Ga]-PSMA-PET compared to histopathology for high-risk prostate cancer}},
  url          = {{http://dx.doi.org/10.2340/1651-226X.2024.39041}},
  doi          = {{10.2340/1651-226X.2024.39041}},
  volume       = {{63}},
  year         = {{2024}},
}