- Email: [email protected]
EP-1680: Assessing tumour necrosis in lunvg cancer with dual energy CT quantitative imaging
S916 ESTRO 36 _______________________________________________________________________________________________
Material and Methods Clinical single-shot EPI-DWI sequence is a rapid imaging technique commonly used for functional imaging. However, EPI techniques are very sensitive to hardware and software imperfection (e.g. B0 inhomogeneity and eddy current) as well as susceptibility effect causing geometrical distortion. The system imperfection is more problematic in MR-Linac with split magnet and less homogeneous magnetic field compared to diagnostic MR systems. SE DWI techniques can reduce the geometrical distortion with the penalty of longer imaging time. Split acquisition of fast spin-echo signals for diffusion imaging (SPLICE) is a DWI technique combined with modified spin echo approach in which is insensitive to the phase of the magnetization. A commercial DWI phantom designed by The Radiological Society of North America Quantitative Imaging Alliance (QIBA) with known Apparent Diffusion Coefficient (ADC) at ice temperature was used in order to determine the optimum ADC measurement sequence for future clinical development. Use of the phantom also allows spatially accurate assessment of geometric distortion compared to CT images acquired using GE Discovery CT 750 HD with Slice thickness of 1.25mm and Voxel size of 0.4883x0.4883x1.25 mm3 DWI imaging was performed using SS EPI (TR/TE = 10000/115 ms) and SS SPLICE (TR/TE = 10000/99 ms) with voxel size = 1.72x1.72mm; slice thickness = 4mm; number of slices=25; and b values = 0, 500, 900, 2000 s/mm2 . Results Qualitative assessment of the geometrical distortion shows significant improvement using SPLICE-DWI against EPI-DWI compared to CT images as shown in figure 1. Quantitative ADC measurement revealed a consistency between measured values using DWI-EPI sequence acquired on Diagnostic MRI system and MR-Linac system in room temperature. The measured values in room temperature are about 33% larger than ADC values measured in 0oC which is in agreement with our previous experiments on diagnostic MRI systems. However, the measured ADC values using SPLICE have larger variations specifically in higher b-values.
Radiofísica y Protección Radiológica, Valencia, Spain 2 Fundación Instituto Valenciano de Oncología, Servicio de Radiología, Valencia, Spain 3 Fundación Instituto Valenciano de Oncología, Servicio de Anatomía Patológica, Valencia, Spain 4 Onkologikoa, Servicio de Radiofísica y Protección Radiológica, San Sebastián, Spain 5 Fundación Instituto Valenciano de Oncología, Servicio de Radioterapia, Valencia, Spain Purpose or Objective To assess if dual energy computed tomography (DECT) quantitative imaging can distinguish necrotic tumours in lung cancer. Material and Methods From July 2013 to June 2016, 83 patients who underwent a DECT study were reviewed for their lung tumour necrosis status (33 positive; 50 negative). Lesion size varied considerably: the mean lesion volume was 15 cm3 (range 0.05-138 cm3). Malignant lesions were predominantly adenocarcinoma (77.1%), squamous cell carcinoma (13.2%) and metastases (7.2%). DECT examination was performed on a Discovery CT 750 HD scanner (GE Healthcare, WI, USA). Patients were injected with 1.35 ml/kg of body weight of non-ionic iodinated contrast material at 4 ml/s (Iopamidol, 300 mg/ml; Bracco, Italy). A Gemstone Spectral Imaging (GSI) DECT exam of the entire chest was performed at arterial phase. Lesion volume was semi-automatically segmented using Dexus lung nodule function (ADW4.6; GE Healthcare, USA) by two radiologists. Images for quantitative iodine content ρI (mg/cm3) and effective atomic number (Zeff) were reconstructed. Maximum, mean and standard deviation values were recorded for both parameters and for conventional HU image. Lesion volume and diameter were also registered. Inter- and intra-observer intraclass correlation coefficient (ICC) was studied. Bilateral statistical analysis was performed using the Mann-Whitney U test. Due to multiple comparisons, Bonferroni adjustment was made and significance was set at p < 0.007. Receiver operating characteristic (ROC) curves were generated and diagnostic capability was determined by calculating the area under the ROC curve (AUC). The licensed statistical software package SPSS 20 (IBM, Somers, NY, USA) was used. Results Reproducibility of intraobserver lung lesion the ICC was 0.95 (CI 95% 0.80–0.98) and interobserver ICC was 0.92 (CI 95% 0.70–0.98). The bivariate analysis for distinguishing necrotic from nonnecrotic lesions revealed statistically significant differences. Larger lesions presented more necrosis than smaller ones, as previously known in the literature. Values for p, AUC and its 95% confidence level interval are shown in Table 1.
Conclusion The SPLICE DWI showed improved spatial fidelity compared to EPI-DWI. This is particularly beneficial in MRgRT due to importance of geometrical fidelity. The SPLICE-DWI sequence needs further modifications and calibrations to achieve more accurate ADC measurement. EP-1680 Assessing tumour necrosis in lunvg cancer with dual energy CT quantitative imaging V. González-Pérez1, E. Arana2, J. Cruz3, M. Barrios2, F. Blázquez1, A. Bartrés4, L. Oliver1, V. Campo1, C. Bosó1, P. Sanamaría5, V. Crispín1 1 Fundación Instituto Valenciano de Oncología, Servicio de
Box-whisker and ROC plots are displayed in Fig. 1 for mean Zeff variable, which presented highest AUC (0.890). Mean
S917 ESTRO 36 _______________________________________________________________________________________________
Zeff presented a 84.0% sensitivity and 81.8% specificity for a threshold of 8.96 in ROC curves.
Conclusion DECT imaging gives information on tumour necrosis. Quantitative parameters (ρI and Zeff) showed better sensibility and specificity compared to standard HU imaging. Mean Zeff showed better correlation with necrosis status, due to necrotic core absorbs less iodine contrast. Our approach has some advantages. Whole tumour semiautomatic contouring had excellent reproducibility. No cases were excluded due to geometry or mediastinal contact. This method could be a solid approach to assess necrosis condition. However, we have not studied relationship with the actual location of necrosis, so it would not be useful for dose-painting protocols at necrotic core. EP-1681 [C11]Choline PET/MRI for Prostate Cancer: Identify Imaging Characteristics Predicting Metastasis J.R. Tseng1, L.Y. Yang2, H.Y. Chang2, T.C. Yen1 1 Chang Gung Memorial Hospital at Linkou, Nuclear Medicine and Molecular Imaging Center, Kwei-ShanTaoyuan City, Taiwan 2 Chang Gung Memorial Hospital at Linkou, Biostatistics Unit- Clinical Trial Center of Chang Gung Memorial Hospital, Kwei-Shan- Taoyuan City, Taiwan Purpose or Objective Intergraded PET/MRI is a powerful imaging modality for prostate cancer (Pca) in several aspects, from cancer detection, primary staging, to staging of recurrent Pca. The goal of primary staging is to detect metastatic spread from the main tumor. In high risk Pca patients (PSA >20 ng/ml, or Gleason score of 8–10, or clinical stage T3a), intergraded PET/MRI imaging may have great potential to change clinical management. In the current study, we aimed to identify imaging characteristics of main tumor which can significantly predict distant metastasis. Material and Methods This prospective clinical study was approved by the Ethics Committee (approval 102-3271A and 103-4561C). Since January 2015 to June 2016, total 30 Pca patients committed high risk criteria were enrolled to conduct whole body integrated [C11]Choline PET/MRI (biograph mMR, Simens). The PET and MRI imaging was interpreted independently by one clinically-experienced nuclear medicine physician and radiologist. In the PET imaging analysis, main tumors were segmented using PMOD 3.3 software package. The borders of volumes of interest were set by manual adjustment to avoid physiological [C11]Choline uptake in the urine or intestine. The tumor boundaries were automatically contoured based on the thresholds of SUV 2.65. The gray-level run length encoding matrix (GLRLM) was used for assessing the regional texture features. In the MRI imaging analysis, anatomic (T2weighted MRI) and functional (diffusion-weighted MRI) imaging features were documented. Multivariate classification and regression tree analysis was used to determine the best combination of variables and the related cutoffs to predict risk for distant metastasis. Results The mean age is 70.1±6.2 years, and the mean PSA level is 91.6 ± 139.4 ng/ml. In these 30 patients, 26 (87%) are categorized as clinical stage IV, 4 (13%) as stage III. Fifteen
(50%) patients have distant metastasis, including 7 (23%) non-regional lymph nodes metastasis, 11 (36%) bone metastasis, 1 (3%) visceral organ metastasis. The individual clinical risk factors (PSA >20 ng/ml, or Gleason score of 8–10, or clinical stage T3a) are not significantly associated with distant metastasis (P-value is 0.493, 0.087, 0.109, respectively). In the multivariate forward analysis, imaging characteristics of main tumor side wall invasion by anatomical T2 MRI is the only significant risk factor predicting distant metastasis (odds ratio 42.25, confidence interval 5.1-346.5, P-value <0.001). The PET regional tumor texture features can further divide patients into with or without distant metastasis by using high intensity long run emphasis value > -0.40 and low intensity run emphasis value <0.26 (Figure 1). The Sensitivity and specificity of the multivariate tree model was 80% and 80%, respectively.
Conclusion By providing excellent anatomical, functional, and metabolic information, integrated PET/MR enhances the staging of metastatic disease in high risk Pca. Imaging characteristics including pelvic side wall invasion and tumor metabolic heterogeneity may have crucial role in patient management. EP-1682 Comparison of SUV based on different ROIs and VOIs definitions: a multi-center 4D phantom study M. Lambrecht1, K. Ortega Marin1, M. La Fontaine2, J.J. Sonke2, R. Boellaard3, M. Verheij2, C.W. Hurkmans1 1 Catharina Ziekenhuis, Physics/Radiotherapy, Eindhoven, The Netherlands 2 Netherlands cancer institute, Radiotherapy, Amsterdam, The Netherlands 3 University medical center- university of Groningen, Nuclear medicine, Groningen, The Netherlands Purpose or Objective In the context of the EORTC LungTech trial, a QA procedure including a PET/CT credentialing has been developed. This procedure will ultimately allow us to pool data from 23 institutions with the overall goal of investigating the impact of tumour motion on quantification. As no standardised procedure exists under respiratory conditions, we investigated the variability of 14 SUV metrics to assess their robustness over respiratory noise. Material and Methods The customized CIRS-008A phantom was scanned at 13 institutions. This phantom consists of a 18 cm long body, a rod attached to a motion actuator, and a sphere of either 1.5 or 2.5cm diameters. Body, rods and spheres were filled with homogeneous 18FDG solutions representative of activity concentrations in mediastinum, lung and tumour for a 70kg patient. Three respiratory patterns with peak-to-peak amplitudes and periods of 15mm/3sec, 15mm/6sec and 25mm/4sec were tested. Prior to scanning in respiratory condition, a 3D static PET/CT was acquired as reference. During motion, images
Material and Methods Clinical single-shot EPI-DWI sequence is a rapid imaging technique commonly used for functional imaging. However, EPI techniques are very sensitive to hardware and software imperfection (e.g. B0 inhomogeneity and eddy current) as well as susceptibility effect causing geometrical distortion. The system imperfection is more problematic in MR-Linac with split magnet and less homogeneous magnetic field compared to diagnostic MR systems. SE DWI techniques can reduce the geometrical distortion with the penalty of longer imaging time. Split acquisition of fast spin-echo signals for diffusion imaging (SPLICE) is a DWI technique combined with modified spin echo approach in which is insensitive to the phase of the magnetization. A commercial DWI phantom designed by The Radiological Society of North America Quantitative Imaging Alliance (QIBA) with known Apparent Diffusion Coefficient (ADC) at ice temperature was used in order to determine the optimum ADC measurement sequence for future clinical development. Use of the phantom also allows spatially accurate assessment of geometric distortion compared to CT images acquired using GE Discovery CT 750 HD with Slice thickness of 1.25mm and Voxel size of 0.4883x0.4883x1.25 mm3 DWI imaging was performed using SS EPI (TR/TE = 10000/115 ms) and SS SPLICE (TR/TE = 10000/99 ms) with voxel size = 1.72x1.72mm; slice thickness = 4mm; number of slices=25; and b values = 0, 500, 900, 2000 s/mm2 . Results Qualitative assessment of the geometrical distortion shows significant improvement using SPLICE-DWI against EPI-DWI compared to CT images as shown in figure 1. Quantitative ADC measurement revealed a consistency between measured values using DWI-EPI sequence acquired on Diagnostic MRI system and MR-Linac system in room temperature. The measured values in room temperature are about 33% larger than ADC values measured in 0oC which is in agreement with our previous experiments on diagnostic MRI systems. However, the measured ADC values using SPLICE have larger variations specifically in higher b-values.
Radiofísica y Protección Radiológica, Valencia, Spain 2 Fundación Instituto Valenciano de Oncología, Servicio de Radiología, Valencia, Spain 3 Fundación Instituto Valenciano de Oncología, Servicio de Anatomía Patológica, Valencia, Spain 4 Onkologikoa, Servicio de Radiofísica y Protección Radiológica, San Sebastián, Spain 5 Fundación Instituto Valenciano de Oncología, Servicio de Radioterapia, Valencia, Spain Purpose or Objective To assess if dual energy computed tomography (DECT) quantitative imaging can distinguish necrotic tumours in lung cancer. Material and Methods From July 2013 to June 2016, 83 patients who underwent a DECT study were reviewed for their lung tumour necrosis status (33 positive; 50 negative). Lesion size varied considerably: the mean lesion volume was 15 cm3 (range 0.05-138 cm3). Malignant lesions were predominantly adenocarcinoma (77.1%), squamous cell carcinoma (13.2%) and metastases (7.2%). DECT examination was performed on a Discovery CT 750 HD scanner (GE Healthcare, WI, USA). Patients were injected with 1.35 ml/kg of body weight of non-ionic iodinated contrast material at 4 ml/s (Iopamidol, 300 mg/ml; Bracco, Italy). A Gemstone Spectral Imaging (GSI) DECT exam of the entire chest was performed at arterial phase. Lesion volume was semi-automatically segmented using Dexus lung nodule function (ADW4.6; GE Healthcare, USA) by two radiologists. Images for quantitative iodine content ρI (mg/cm3) and effective atomic number (Zeff) were reconstructed. Maximum, mean and standard deviation values were recorded for both parameters and for conventional HU image. Lesion volume and diameter were also registered. Inter- and intra-observer intraclass correlation coefficient (ICC) was studied. Bilateral statistical analysis was performed using the Mann-Whitney U test. Due to multiple comparisons, Bonferroni adjustment was made and significance was set at p < 0.007. Receiver operating characteristic (ROC) curves were generated and diagnostic capability was determined by calculating the area under the ROC curve (AUC). The licensed statistical software package SPSS 20 (IBM, Somers, NY, USA) was used. Results Reproducibility of intraobserver lung lesion the ICC was 0.95 (CI 95% 0.80–0.98) and interobserver ICC was 0.92 (CI 95% 0.70–0.98). The bivariate analysis for distinguishing necrotic from nonnecrotic lesions revealed statistically significant differences. Larger lesions presented more necrosis than smaller ones, as previously known in the literature. Values for p, AUC and its 95% confidence level interval are shown in Table 1.
Conclusion The SPLICE DWI showed improved spatial fidelity compared to EPI-DWI. This is particularly beneficial in MRgRT due to importance of geometrical fidelity. The SPLICE-DWI sequence needs further modifications and calibrations to achieve more accurate ADC measurement. EP-1680 Assessing tumour necrosis in lunvg cancer with dual energy CT quantitative imaging V. González-Pérez1, E. Arana2, J. Cruz3, M. Barrios2, F. Blázquez1, A. Bartrés4, L. Oliver1, V. Campo1, C. Bosó1, P. Sanamaría5, V. Crispín1 1 Fundación Instituto Valenciano de Oncología, Servicio de
Box-whisker and ROC plots are displayed in Fig. 1 for mean Zeff variable, which presented highest AUC (0.890). Mean
S917 ESTRO 36 _______________________________________________________________________________________________
Zeff presented a 84.0% sensitivity and 81.8% specificity for a threshold of 8.96 in ROC curves.
Conclusion DECT imaging gives information on tumour necrosis. Quantitative parameters (ρI and Zeff) showed better sensibility and specificity compared to standard HU imaging. Mean Zeff showed better correlation with necrosis status, due to necrotic core absorbs less iodine contrast. Our approach has some advantages. Whole tumour semiautomatic contouring had excellent reproducibility. No cases were excluded due to geometry or mediastinal contact. This method could be a solid approach to assess necrosis condition. However, we have not studied relationship with the actual location of necrosis, so it would not be useful for dose-painting protocols at necrotic core. EP-1681 [C11]Choline PET/MRI for Prostate Cancer: Identify Imaging Characteristics Predicting Metastasis J.R. Tseng1, L.Y. Yang2, H.Y. Chang2, T.C. Yen1 1 Chang Gung Memorial Hospital at Linkou, Nuclear Medicine and Molecular Imaging Center, Kwei-ShanTaoyuan City, Taiwan 2 Chang Gung Memorial Hospital at Linkou, Biostatistics Unit- Clinical Trial Center of Chang Gung Memorial Hospital, Kwei-Shan- Taoyuan City, Taiwan Purpose or Objective Intergraded PET/MRI is a powerful imaging modality for prostate cancer (Pca) in several aspects, from cancer detection, primary staging, to staging of recurrent Pca. The goal of primary staging is to detect metastatic spread from the main tumor. In high risk Pca patients (PSA >20 ng/ml, or Gleason score of 8–10, or clinical stage T3a), intergraded PET/MRI imaging may have great potential to change clinical management. In the current study, we aimed to identify imaging characteristics of main tumor which can significantly predict distant metastasis. Material and Methods This prospective clinical study was approved by the Ethics Committee (approval 102-3271A and 103-4561C). Since January 2015 to June 2016, total 30 Pca patients committed high risk criteria were enrolled to conduct whole body integrated [C11]Choline PET/MRI (biograph mMR, Simens). The PET and MRI imaging was interpreted independently by one clinically-experienced nuclear medicine physician and radiologist. In the PET imaging analysis, main tumors were segmented using PMOD 3.3 software package. The borders of volumes of interest were set by manual adjustment to avoid physiological [C11]Choline uptake in the urine or intestine. The tumor boundaries were automatically contoured based on the thresholds of SUV 2.65. The gray-level run length encoding matrix (GLRLM) was used for assessing the regional texture features. In the MRI imaging analysis, anatomic (T2weighted MRI) and functional (diffusion-weighted MRI) imaging features were documented. Multivariate classification and regression tree analysis was used to determine the best combination of variables and the related cutoffs to predict risk for distant metastasis. Results The mean age is 70.1±6.2 years, and the mean PSA level is 91.6 ± 139.4 ng/ml. In these 30 patients, 26 (87%) are categorized as clinical stage IV, 4 (13%) as stage III. Fifteen
(50%) patients have distant metastasis, including 7 (23%) non-regional lymph nodes metastasis, 11 (36%) bone metastasis, 1 (3%) visceral organ metastasis. The individual clinical risk factors (PSA >20 ng/ml, or Gleason score of 8–10, or clinical stage T3a) are not significantly associated with distant metastasis (P-value is 0.493, 0.087, 0.109, respectively). In the multivariate forward analysis, imaging characteristics of main tumor side wall invasion by anatomical T2 MRI is the only significant risk factor predicting distant metastasis (odds ratio 42.25, confidence interval 5.1-346.5, P-value <0.001). The PET regional tumor texture features can further divide patients into with or without distant metastasis by using high intensity long run emphasis value > -0.40 and low intensity run emphasis value <0.26 (Figure 1). The Sensitivity and specificity of the multivariate tree model was 80% and 80%, respectively.
Conclusion By providing excellent anatomical, functional, and metabolic information, integrated PET/MR enhances the staging of metastatic disease in high risk Pca. Imaging characteristics including pelvic side wall invasion and tumor metabolic heterogeneity may have crucial role in patient management. EP-1682 Comparison of SUV based on different ROIs and VOIs definitions: a multi-center 4D phantom study M. Lambrecht1, K. Ortega Marin1, M. La Fontaine2, J.J. Sonke2, R. Boellaard3, M. Verheij2, C.W. Hurkmans1 1 Catharina Ziekenhuis, Physics/Radiotherapy, Eindhoven, The Netherlands 2 Netherlands cancer institute, Radiotherapy, Amsterdam, The Netherlands 3 University medical center- university of Groningen, Nuclear medicine, Groningen, The Netherlands Purpose or Objective In the context of the EORTC LungTech trial, a QA procedure including a PET/CT credentialing has been developed. This procedure will ultimately allow us to pool data from 23 institutions with the overall goal of investigating the impact of tumour motion on quantification. As no standardised procedure exists under respiratory conditions, we investigated the variability of 14 SUV metrics to assess their robustness over respiratory noise. Material and Methods The customized CIRS-008A phantom was scanned at 13 institutions. This phantom consists of a 18 cm long body, a rod attached to a motion actuator, and a sphere of either 1.5 or 2.5cm diameters. Body, rods and spheres were filled with homogeneous 18FDG solutions representative of activity concentrations in mediastinum, lung and tumour for a 70kg patient. Three respiratory patterns with peak-to-peak amplitudes and periods of 15mm/3sec, 15mm/6sec and 25mm/4sec were tested. Prior to scanning in respiratory condition, a 3D static PET/CT was acquired as reference. During motion, images