Marius Hagen1, Matthias Kretschmer2, Florian Würschmidt2, Tobias Gauer3, Christian Giro2, Elias Karsten4, Jörn Lorenzen2. 1. Asklepios Medical School, Hamburg, Germany. 2. Radiological Alliance, Hamburg, Germany. 3. Department of Radiotherapy and Radio-Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. 4. Department of Radiotherapy, University Medical Center Schleswig-Holstein, Kiel, Germany.
Abstract
INTRODUCTION: Artefacts caused by dental implants and hip replacements may impede target volume definition and dose calculation accuracy. The iterative metal artefact reduction (iMAR) algorithm can provide a solution for this problem. The present study compares delineation of gross tumour volumes (GTVs) and organs at risk (OARs) in the pelvic and the head and neck (H & N) regions using computed tomography (CT) with and without iMAR, and thus the practical applicability of iMAR for routine clinical use. METHODS: The native planning CT and CT-iMAR data of two typical clinical cases with image-distorting artefacts were used for multi-institutional contouring and analysis using the Dice similarity coefficient (DSC). GTV/OAR contours were compared with an intraobserver approach and compared to predefined reference structures. RESULTS: Mean volume for GTVprostate in the intraobserver approach decreased from 87 ± 44 cm3 (native CT) to 75 ± 22 cm3 (CT-iMAR) (P = 0.168). Compared to the reference, DSC values for GTVP rostate increased from 0.68 ± 0.15 to 0.78 ± 0.07 (CT vs. iMAR) (P < 0.05). In the H & N region, the reference for GTVT ongue (34 cm3 ) was underestimated on both data sets. No significant improvement in DSC values (0.83 ± 0.06 (native CT) versus 0.86 ± 0.06 (CT-iMAR)) was observed. CONCLUSION: The use of iMAR improves the anatomical delineation at the transition of prostate and bladder in cases of bilateral hip replacement. In the H & N region, anatomical residual structures and experience were apparently sufficient for precise contouring.
INTRODUCTION: Artefacts caused by dental implants and hip replacements may impede target volume definition and dose calculation accuracy. The iterative metalartefact reduction (iMAR) algorithm can provide a solution for this problem. The present study compares delineation of gross tumour volumes (GTVs) and organs at risk (OARs) in the pelvic and the head and neck (H & N) regions using computed tomography (CT) with and without iMAR, and thus the practical applicability of iMAR for routine clinical use. METHODS: The native planning CT and CT-iMAR data of two typical clinical cases with image-distorting artefacts were used for multi-institutional contouring and analysis using the Dice similarity coefficient (DSC). GTV/OAR contours were compared with an intraobserver approach and compared to predefined reference structures. RESULTS: Mean volume for GTVprostate in the intraobserver approach decreased from 87 ± 44 cm3 (native CT) to 75 ± 22 cm3 (CT-iMAR) (P = 0.168). Compared to the reference, DSC values for GTVP rostate increased from 0.68 ± 0.15 to 0.78 ± 0.07 (CT vs. iMAR) (P < 0.05). In the H & N region, the reference for GTVT ongue (34 cm3 ) was underestimated on both data sets. No significant improvement in DSC values (0.83 ± 0.06 (native CT) versus 0.86 ± 0.06 (CT-iMAR)) was observed. CONCLUSION: The use of iMAR improves the anatomical delineation at the transition of prostate and bladder in cases of bilateral hip replacement. In the H & N region, anatomical residual structures and experience were apparently sufficient for precise contouring.
Authors: Janna Morawitz; Ole Martin; Johannes Boos; Lino M Sawicki; Katrin Wingendorf; Martin Sedlmair; Eduards Mamlins; Christina Antke; Gerald Antoch; Benedikt M Schaarschmidt Journal: Diagnostics (Basel) Date: 2022-02-01