Practical Radiation Oncology: April-June Supplement 2013 separated into bins for every 400 cGy of absorbed dose and the bin average values plotted similarly. Results: Four of the five patients showed a significant positive correlation (R2 = 0.18, 0.70, 0.81, 0.82 and 0.89, respectively) between PET uptake difference in the targeted region and the absorbed dose for the binned voxels. Conclusions: By considering larger ensembles of voxels, such as organ average absorbed dose or the dose bins considered here, valuable information may be obtained. The dose–response correlations as measured by FDG-PET difference potentially underlines the importance of FDG-PET as a measure of response, as well as the value of voxelized information. Author Disclosure Block: R.F. Hobbs: None. Y. Le: None. E. Armour: None. J. Efron: None. N. Azad: None. L. Diaz: None. R. Wahl: None. G. Sgouros: None. S. Gearhardt: None. J. Hermann: None.
175 Feasibility Study of 4D Perfusion CT for Hepatocellular Carcinoma Patients Treated With Radiation and Sorafenib C. Coolens, B. Driscoll, L. Dawson, Princess Margaret Hospital, Toronto, ON, Canada Purpose/Objectives: Quantitative functional imaging methods measuring vascular change have become an important component in optimizing the timing of anti-angiogenic therapies and radiation therapy. Dynamic contrast-enhanced (DCE) CT, with high resolution and clinical convenience, is a key potential method in this regard. Clinical Trials in Hepatocellular carcinoma (HCC) patients treated with Radiation and Sorafenib are ongoing. Recently, a novel Functional Analysis method for DCE (FADE) Imaging was developed based on 4D DCE data acquired with a 320-slice CT scanner. This technology provides advantages over conventional DCE CT methods, allowing simultaneous fast dynamic scanning of arterial input and tissues of interest. This work aims to assess the feasibility of 4D FADE CT in providing 3D perfusion parameter maps in a group of HCC patients and assess its sensitivity in evaluating changes in liver and tumor perfusion as a response to treatment. Materials/Methods: Three patients with HCC, treated with stereotactic body radiation (SBRT) and Sorafenib, underwent 4D DCE CT on a 320slice CT as part of a REB approved protocol that allowed perfusion imaging at 5 different times during and following treatment. Sorafenib was delivered for one week prior to SBRT, then during and for 4 weeks after at study dose, then escalation up to standard of care dose. SBRT dose of 54Gy in 6 fractions was given over 2 weeks. Deformable registration was used to reduce residual liver motion during DCE CT. 4D FADE was performed on primary liver GTV and normal liver. Metrics of interest were perfusion parameters Ktrans, Kep & Vb as calculated with a modified Tofts model; Time to Onset, Slope and Area under the curve (AUC). Histogram analysis and 3D visualization were performed to attempt to observe temporal changes over the course of treatment. Results: 3D perfusion results were obtained for all scans. One patient interrupted treatment for non-medical reasons. In the GTV, a reduction Ktrans and AUC was seen over the course of treatment and as early as after 1 week of Sorafenib. A marked reduction in normal liver perfusion was also seen throughout the course of treatment both in Ktrans and AUC values. This was observed for all dose levels between baseline and 3m follow-up (p = 0.0021 for 50Gy). The perfusion reduction was strongly dependent on dose exposure (p = 0.0012). Conclusions: The proposed methodology has demonstrated its feasibility in creating 3D volumes of functional vasculature and perfused tissue in the liver. This is an important milestone towards achieving a volumetric, quantitative functional imaging method. Author Disclosure Block: C. Coolens: None. B. Driscoll: None. L. Dawson: None.
Poster Presentations
S29
176 A Translational Feline Model of Oral Squamous Cell Carcinoma for Evaluating Tumor Volume Delineation With PET/CT E. Randall, H. Yoshikawa, S. Kraft, S. LaRue, Colorado State University, Fort Collins, CO Purpose/Objectives: Oral squamous cell carcinoma (SCC) is a locally invasive naturally occurring tumor in cats that responds poorly to radiation therapy. Most cats succumb to failure from local recurrence within 6 months. Feline SCC has comparable histological characteristics, higher pretreatment epidermal growth factor (EGRF) and microvascular density (MDV) values that are associated with a worsened prognosis, similar to human oral SCC. Unlike rodent models, spontaneous tumors in cats are heterogeneous and often hypoxic. The tumors are large enough to obtain adequate biopsy material, and the cats can be imaged and treated with the same modalities as cancer patients. Positron emission tomography- computed tomography (PET/CT) with 18F-fluoro-2deoxy-D-glucose detects areas with higher glucose metabolism. The goal of the current study was to evaluate the role of 18F-FDG PET for feline radiation therapy patients with oral SCC, as a model of tumor delineation for human disease. Materials/Methods: Twelve cats with oral SCC underwent pretreatment 18F-FDG PET/CT with a Philips Gemini TF PET/CT Big Bore instrument. Two different gross tumor volumes (GTV), based solely on either contrast-enhanced CT or 18F-FDG PET were created and compared (GTVCT and GTVPET, respectively). To evaluate the degree of overlap between these two GTVs, “mismatch fractions” were calculated. Results: All tumors were FDG avid and conspicuous, with an average maximal standard uptake value of 9.88 +/− 5.33 SD. Lymphoidal metastases were normal on CT but intensely hypermetabolic on FDGPET images. FDG-PET provided unique and therapeutically relevant supplemental information to CT for evaluating feline oral SCC. GTVPET was significantly smaller than GTVCT in the mandibular/maxillary SCC group (n = 8, P = 0.006) as well as in total (n = 12, P = 0.017), but not in the lingual/laryngeal group (n = 4, P = 0.71). Mismatch fraction analysis revealed that most of the lingual/laryngeal patients had a large area of 18 F-FDG avid region outside of GTVCT. Their soft tissue infiltrate was highly visible on PET images but only subtle on CT images. The mismatch fraction was significantly less in the mandibular/maxillary group (P = 0.028) although some patients in the latter group also had a large 18F-FDG avid region outside the GTVCT. 18F-FDG PET enabled detection of more potential primary tumor both in the lingual/laryngeal and mandibular/maxillary cases. Conclusions: Feline oral SCC are naturally occurring tumors sharing many features of human oral SCC including morphology, biomarkers, tumor microenvironment and FDG-PET/CT characteristics. This model represents a valuable preclinical translational model that could be used to evaluate new methods for imaging and modulating tumor hypoxia and other malignant features. Author Disclosure Block: E. Randall: None. H. Yoshikawa: None. S. Kraft: None. S. LaRue: None.
177 Positron Emission Tomography Texture Analysis of Necrosis in Primary Adenocarcinomas of the Lung J.A. Oliver 1,2, M. Budzevich 1, G. Zhang 1,2, E.G. Moros 1,2, K. Latifi 1, C. Kuykendall 1, S. Hoffe 1, J. Montilla-Soler 1, E. Eikman 1, T. Dilling 1, 2 1 Moffitt Cancer Center, Tampa, FL, University of South Florida, Tampa, FL Purpose/Objectives: To determine if the spatial and statistical properties of Positron Emission Tomography (PET) image texture would differ between lung tumors with a necrotic core and nonnecrotic tumors.
175 Feasibility Study of 4D Perfusion CT for Hepatocellular Carcinoma Patients Treated With Radiation and Sorafenib C. Coolens, B. Driscoll, L. Dawson, Princess Margaret Hospital, Toronto, ON, Canada Purpose/Objectives: Quantitative functional imaging methods measuring vascular change have become an important component in optimizing the timing of anti-angiogenic therapies and radiation therapy. Dynamic contrast-enhanced (DCE) CT, with high resolution and clinical convenience, is a key potential method in this regard. Clinical Trials in Hepatocellular carcinoma (HCC) patients treated with Radiation and Sorafenib are ongoing. Recently, a novel Functional Analysis method for DCE (FADE) Imaging was developed based on 4D DCE data acquired with a 320-slice CT scanner. This technology provides advantages over conventional DCE CT methods, allowing simultaneous fast dynamic scanning of arterial input and tissues of interest. This work aims to assess the feasibility of 4D FADE CT in providing 3D perfusion parameter maps in a group of HCC patients and assess its sensitivity in evaluating changes in liver and tumor perfusion as a response to treatment. Materials/Methods: Three patients with HCC, treated with stereotactic body radiation (SBRT) and Sorafenib, underwent 4D DCE CT on a 320slice CT as part of a REB approved protocol that allowed perfusion imaging at 5 different times during and following treatment. Sorafenib was delivered for one week prior to SBRT, then during and for 4 weeks after at study dose, then escalation up to standard of care dose. SBRT dose of 54Gy in 6 fractions was given over 2 weeks. Deformable registration was used to reduce residual liver motion during DCE CT. 4D FADE was performed on primary liver GTV and normal liver. Metrics of interest were perfusion parameters Ktrans, Kep & Vb as calculated with a modified Tofts model; Time to Onset, Slope and Area under the curve (AUC). Histogram analysis and 3D visualization were performed to attempt to observe temporal changes over the course of treatment. Results: 3D perfusion results were obtained for all scans. One patient interrupted treatment for non-medical reasons. In the GTV, a reduction Ktrans and AUC was seen over the course of treatment and as early as after 1 week of Sorafenib. A marked reduction in normal liver perfusion was also seen throughout the course of treatment both in Ktrans and AUC values. This was observed for all dose levels between baseline and 3m follow-up (p = 0.0021 for 50Gy). The perfusion reduction was strongly dependent on dose exposure (p = 0.0012). Conclusions: The proposed methodology has demonstrated its feasibility in creating 3D volumes of functional vasculature and perfused tissue in the liver. This is an important milestone towards achieving a volumetric, quantitative functional imaging method. Author Disclosure Block: C. Coolens: None. B. Driscoll: None. L. Dawson: None.
Poster Presentations
S29
176 A Translational Feline Model of Oral Squamous Cell Carcinoma for Evaluating Tumor Volume Delineation With PET/CT E. Randall, H. Yoshikawa, S. Kraft, S. LaRue, Colorado State University, Fort Collins, CO Purpose/Objectives: Oral squamous cell carcinoma (SCC) is a locally invasive naturally occurring tumor in cats that responds poorly to radiation therapy. Most cats succumb to failure from local recurrence within 6 months. Feline SCC has comparable histological characteristics, higher pretreatment epidermal growth factor (EGRF) and microvascular density (MDV) values that are associated with a worsened prognosis, similar to human oral SCC. Unlike rodent models, spontaneous tumors in cats are heterogeneous and often hypoxic. The tumors are large enough to obtain adequate biopsy material, and the cats can be imaged and treated with the same modalities as cancer patients. Positron emission tomography- computed tomography (PET/CT) with 18F-fluoro-2deoxy-D-glucose detects areas with higher glucose metabolism. The goal of the current study was to evaluate the role of 18F-FDG PET for feline radiation therapy patients with oral SCC, as a model of tumor delineation for human disease. Materials/Methods: Twelve cats with oral SCC underwent pretreatment 18F-FDG PET/CT with a Philips Gemini TF PET/CT Big Bore instrument. Two different gross tumor volumes (GTV), based solely on either contrast-enhanced CT or 18F-FDG PET were created and compared (GTVCT and GTVPET, respectively). To evaluate the degree of overlap between these two GTVs, “mismatch fractions” were calculated. Results: All tumors were FDG avid and conspicuous, with an average maximal standard uptake value of 9.88 +/− 5.33 SD. Lymphoidal metastases were normal on CT but intensely hypermetabolic on FDGPET images. FDG-PET provided unique and therapeutically relevant supplemental information to CT for evaluating feline oral SCC. GTVPET was significantly smaller than GTVCT in the mandibular/maxillary SCC group (n = 8, P = 0.006) as well as in total (n = 12, P = 0.017), but not in the lingual/laryngeal group (n = 4, P = 0.71). Mismatch fraction analysis revealed that most of the lingual/laryngeal patients had a large area of 18 F-FDG avid region outside of GTVCT. Their soft tissue infiltrate was highly visible on PET images but only subtle on CT images. The mismatch fraction was significantly less in the mandibular/maxillary group (P = 0.028) although some patients in the latter group also had a large 18F-FDG avid region outside the GTVCT. 18F-FDG PET enabled detection of more potential primary tumor both in the lingual/laryngeal and mandibular/maxillary cases. Conclusions: Feline oral SCC are naturally occurring tumors sharing many features of human oral SCC including morphology, biomarkers, tumor microenvironment and FDG-PET/CT characteristics. This model represents a valuable preclinical translational model that could be used to evaluate new methods for imaging and modulating tumor hypoxia and other malignant features. Author Disclosure Block: E. Randall: None. H. Yoshikawa: None. S. Kraft: None. S. LaRue: None.
177 Positron Emission Tomography Texture Analysis of Necrosis in Primary Adenocarcinomas of the Lung J.A. Oliver 1,2, M. Budzevich 1, G. Zhang 1,2, E.G. Moros 1,2, K. Latifi 1, C. Kuykendall 1, S. Hoffe 1, J. Montilla-Soler 1, E. Eikman 1, T. Dilling 1, 2 1 Moffitt Cancer Center, Tampa, FL, University of South Florida, Tampa, FL Purpose/Objectives: To determine if the spatial and statistical properties of Positron Emission Tomography (PET) image texture would differ between lung tumors with a necrotic core and nonnecrotic tumors.
