94 Comparison of 2D and 3D algorithms for adding a margin to the gross tumor volume in the conformal radiotherapy planning of prostate cancer

In this simulation study, we assessed differences in gross tumor volume (GTV) in a series of skull base paragangliomas (SBPGLs) using magnetic resonance imaging (MRI), 18F-dihydroxyphenylalanine (18F-FDOPA) combined positron emission tomography/computed tomography (PET/CT), and 18F-FDOPA PET/MRI images obtained by rigid alignment of PET and MRI. GTV was delineated in 16 patients with SBPGLs on MRI (GTVMRI), 18F-FDOPA PET/CT (GTVPET), and combined PET/MRI (GTVPET/MRI). GTVPET/MRI was the union of GTVMRI and GTVPET after visual adjustment. Three observers delineated GTVMRI and GTVPET/MRI independently. Excellent interobserver reproducibility was found for both GTVMRI and GTVPET/MRI. GTVPET and GTVMRI were not significantly different. However, there was some spatial difference between the locations of GTVMRI, GTVPET, and GTVPET/MRI. The Dice similarity coefficient median value was 0.4 between PET/CT and MRI, and 0.8 between MRI and PET/MRI. The combined use of PET/MRI produced a larger GTV than MRI alone. Nevertheless, both the target-delivered dose and organs-at-risk conservancy were respected when treatment was planned on the PET/MRI-matched data set. Future integration of 18F-FDOPA PET/CT into clinical practice will be necessary to evaluate the influence of this diagnostic modality on SBPGL therapeutic management. If the clinical utility of 18F-FDOPA PET/CT and/or PET/MRI is confirmed, GTVPET/MRI should be considered for tailored radiotherapy planning in patients with SBPGL.

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The clinical application of 4D 18F-FDG PET/CT on gross tumor volume delineation for radiotherapy planning in esophageal squamous cell cancer

Journal of Radiation Research ◽

10.1093/jrr/rrs009 ◽

2012 ◽

Vol 53 (4) ◽

pp. 594-600 ◽

Cited By ~ 16

Author(s):

Y.-C. Wang ◽

T.-C. Hsieh ◽

C.-Y. Yu ◽

K.-Y. Yen ◽

S.-W. Chen ◽

...

Keyword(s):

Fdg Pet ◽

Gross Tumor Volume ◽

Tumor Volume ◽

Squamous Cell Cancer ◽

Cell Cancer ◽

Radiotherapy Planning ◽

Volume Delineation ◽

Pet Ct ◽

18F Fdg ◽

Fdg Pet Ct

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Pattern of Recurrence of Glioblastoma Versus Grade 4 IDH-Mutant Astrocytoma Following Chemoradiation

10.21203/rs.3.rs-1079782/v1 ◽

2021 ◽

Author(s):

James Stewart ◽

Arjun Sahgal ◽

Aimee K.M. Chan ◽

Hany Soliman ◽

Chia-Lin Tseng ◽

...

Keyword(s):

Gross Tumor Volume ◽

Clinical Target Volume ◽

Tumor Volume ◽

Extent Of Resection ◽

Target Volume ◽

Radiotherapy Planning ◽

Recurrence Pattern ◽

Wild Type ◽

Failure Patterns ◽

Pattern Of Recurrence

Abstract Purpose To quantitatively compare the recurrence pattern of glioblastoma (IDH-wild type) versus grade 4 IDH-mutant astrocytoma (herein referred to as wtIDH and mutIDH, respectively) following primary chemoradiation. Methods Twenty-two wtIDH and 22 mutIDH patients matched by sex, extent of resection, and corpus callosum involvement were enrolled. The recurrent gross tumor volume (rGTV) was compared with both the gross tumor volume (GTV) and clinical target volume (CTV) from radiotherapy planning. Failure patterns were quantified by the incidence and volume of the rGTV outside the GTV and CTV, and positional differences of the rGTV centroid from the GTV and CTV. Results The GTV was smaller in wtIDH compared to the mutIDH group (mean±SD: 46.5±26.0 cm3 v. 72.2±45.4 cm3, p=0.026). The rGTV was 10.7±26.9 cm3 and 46.9±55.0 cm3 smaller than the GTV for the same groups (p=0.018). The rGTV extended outside the GTV in 22 (100%) and 15 (68%) (p=0.009) of wtIDH and mutIDH patients, respectively; however, the volume of rGTV outside the GTV was not significantly different (12.4±16.1 cm3 vs. 8.4±14.2 cm3, p=0.443). The rGTV metrics extending outside the CTV was not different between the groups. The rGTV centroid was within 5.7 mm of the closest GTV edge for 21 (95%) and 22 (100%) of wtIDH and mutIDH patients, respectively. Conclusion The rGTV extended beyond the GTV less often in mutIDH patients, suggesting limited margin radiotherapy could be beneficial in this group. The results support the study of small margin adaptive radiotherapy per the ongoing UNITED MR-Linac 5 mm CTV trial (NCT04726397).

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Isotropic Expansion of the Intraprostatic Gross Tumor Volume of Primary Prostate Cancer Patients Defined in MRI—A Correlation Study With Whole Mount Histopathological Information as Reference

Frontiers in Oncology ◽

10.3389/fonc.2020.596756 ◽

2020 ◽

Vol 10 ◽

Author(s):

Maria Kramer ◽

Simon K. B. Spohn ◽

Selina Kiefer ◽

Lara Ceci ◽

August Sigle ◽

...

Keyword(s):

Prostate Cancer ◽

Gross Tumor Volume ◽

Tumor Volume ◽

Ex Vivo ◽

Standard Of Care ◽

Volumetric Analysis ◽

Correlation Study ◽

Lesion Detection ◽

Coverage Ratio ◽

Primary Prostate Cancer

IntroductionAn accurate delineation of the intraprostatic gross tumor volume (GTV) is of importance for focal treatment in patients with primary prostate cancer (PCa). Multiparametric MRI (mpMRI) is the standard of care for lesion detection but has been shown to underestimate GTV. This study investigated how far the GTV has to be expanded in MRI in order to reach concordance with the histopathological reference and whether this strategy is practicable in clinical routine.Patients and MethodsTwenty-two patients with planned prostatectomy and preceded 3 Tesla mpMRI were prospectively examined. After surgery, PCa contours delineated on histopathological slides (GTV-Histo) were superimposed on MRI using ex-vivo imaging as support for co-registration. According to the PI-RADSv2 classification, GTV was manually delineated in MRI (GTV-MRI) by two experts in consensus. For volumetric analysis, we compared GTV-MRI and GTV-Histo. Subsequently, we isotropically enlarged GTV-MRI in 1 mm increments within the prostate and also compared those with GTV-Histo regarding the absolute volumes. For evaluating the spatial accuracy, we considered the coverage ratio of GTV-Histo, the Sørensen–Dice coefficient (DSC), as well as the contact with the urethra.ResultsIn 19 of 22 patients MRI underestimated the intraprostatic tumor volume compared to histopathological reference: median GTV-Histo (4.7 cm3, IQR: 2.5–18.8) was significantly (p<0.001) lager than median GTV-MRI (2.6 cm3, IQR: 1.2–6.9). A median expansion of 1 mm (range: 0–4 mm) adjusted the initial GTV-MRI to at least the volume of GTV-Histo (GTVexp-MRI). Original GTV-MRI and expansion with 1, 2, 3, and 4 mm covered in median 39% (IQR: 2%–78%), 62% (10%–91%), 70% (15%–95%), 80% (21–100), 87% (25%–100%) of GTV-Histo, respectively. Best DSC (median: 0.54) between GTV-Histo and GTV-MRI was achieved by median expansion of 2 mm. The urethra was covered by initial GTVs-MRI in eight patients (36%). After applying an expansion with 2 mm the urethra was covered in one more patient by GTV-MRI. ConclusionUsing histopathology as reference, we demonstrated that MRI underestimates intraprostatic tumor volume. A 2 mm–expansion may improve accurate GTV-delineation while respecting the balance between histological tumor coverage and overtreatment.

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Comparison of Manual and Semi-Automatic [18F]PSMA-1007 PET Based Contouring Techniques for Intraprostatic Tumor Delineation in Patients With Primary Prostate Cancer and Validation With Histopathology as Standard of Reference

Frontiers in Oncology ◽

10.3389/fonc.2020.600690 ◽

2020 ◽

Vol 10 ◽

Author(s):

Simon K. B. Spohn ◽

Maria Kramer ◽

Selina Kiefer ◽

Peter Bronsert ◽

August Sigle ◽

...

Keyword(s):

Prostate Cancer ◽

Gross Tumor Volume ◽

Interobserver Agreement ◽

Tumor Volume ◽

High Sensitivity ◽

Dice Similarity Coefficient ◽

Primary Prostate Cancer ◽

Psma Pet ◽

Significant Difference ◽

Automatic Contouring

PurposeAccurate contouring of intraprostatic gross tumor volume (GTV) is pivotal for successful delivery of focal therapies and for biopsy guidance in patients with primary prostate cancer (PCa). Contouring of GTVs, using 18-Fluor labeled tracer prostate specific membrane antigen positron emission tomography ([18F]PSMA-1007/PET) has not been examined yet.Patients and MethodsTen Patients with primary PCa who underwent [18F]PSMA-1007 PET followed by radical prostatectomy were prospectively enrolled. Coregistered histopathological gross tumor volume (GTV-Histo) was used as standard of reference. PSMA-PET images were contoured on two ways: (1) manual contouring with PET scaling SUVmin-max: 0–10 was performed by three teams with different levels of experience. Team 1 repeated contouring at a different time point, resulting in n = 4 manual contours. (2) Semi-automatic contouring approaches using SUVmax thresholds of 20–50% were performed. Interobserver agreement was assessed for manual contouring by calculating the Dice Similarity Coefficient (DSC) and for all approaches sensitivity, specificity were calculated by dividing the prostate in each CT slice into four equal quadrants under consideration of histopathology as standard of reference.ResultsManual contouring yielded an excellent interobserver agreement with a median DSC of 0.90 (range 0.87–0.94). Volumes derived from scaling SUVmin-max 0–10 showed no statistically significant difference from GTV-Histo and high sensitivities (median 87%, range 84–90%) and specificities (median 96%, range 96–100%). GTVs using semi-automatic segmentation applying a threshold of 20–40% of SUVmax showed no significant difference in absolute volumes to GTV-Histo, GTV-SUV50% was significantly smaller. Best performing semi-automatic contour (GTV-SUV20%) achieved high sensitivity (median 93%) and specificity (median 96%). There was no statistically significant difference to SUVmin-max 0–10.ConclusionManual contouring with PET scaling SUVmin-max 0–10 and semi-automatic contouring applying a threshold of 20% of SUVmax achieved high sensitivities and very high specificities and are recommended for [18F]PSMA-1007 PET based focal therapy approaches. Providing high specificities, semi-automatic approaches applying thresholds of 30–40% of SUVmax are recommend for biopsy guidance.

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Evaluation of Hybrid PET/MRI for Gross Tumor Volume (GTV) Delineation in Liver Cancer Radiotherapy

10.21203/rs.3.rs-94459/v1 ◽

2020 ◽

Author(s):

Yan-Nan Zhang ◽

Xin Lu ◽

Zhen-Guo Lu ◽

Li-Ping Fu ◽

Jun Zhao ◽

...

Keyword(s):

Statistical Analysis ◽

Liver Cancer ◽

Gross Tumor Volume ◽

Tumor Volume ◽

Target Volume ◽

Biological Data ◽

Radiotherapy Planning ◽

Dice Similarity Coefficient ◽

Volume Delineation ◽

Positron Emission

Abstract Background: Hybrid 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/magnetic resonance imaging (PET/MRI) has been increasingly incorporated into the practice of radiation oncologists since it contains both anatomical and biological data and may bring about personalized radiation plans for each patient. The objective of this study was to evaluate the feasibility of gross tumor volume (GTV) delineation from hybrid PET/MRI compared with that from current-practice MRI during radiotherapy planning in patients with liver cancer. Methods: Twelve patients (eighteen lesions) with liver cancer were enrolled in this study. We chose one of the most popular delineating methods—the visual method—in this study, and three physicians delineated the target volume of each lesion from MRI, PET, and hybrid PET/MRI images. The difference and correlation of GTV values obtained by MRI, PET and hybrid PET/MRI were subjected to statistical analysis. In addition, the Dice similarity coefficient (DSC) was calculated to assess the spatial overlap. GTV-MRI was set as a reference. Results: Most GTV-PET/MRI (83%) and 50% of GTV-PET were larger than the reference GTV-MRI. Statistical analysis revealed that GTV-PET/MRI (p=0.021) diverged statistically significantly from the reference GTV-MRI. In contrast, GTV-PET (p=0.266) was not significantly different from GTV-MRI. GTV-PET (r=0.991, p<0.001) and GTV-PET/MRI (r=0.997, p<0.001) were significantly related to GTV-MRI. The average DSC value between GTV-MRI and GTV-PET was 0.45 (range 0–0.90) and that between GTV-MRI and GTV-PET/MRI was 0.76 (range 0.43–0.90). Conclusions: With the database used, PET/MRI-based target volume delineation for liver cancer is feasible. The larger GTV-PET/MRI may allow adequate irradiation of the diseased tissue and improved treatment effect.

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