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CT for Patients with Esophageal Cancer
I. J. Radiation Oncology d Biology d Physics
S252
Volume 72, Number 1, Supplement, 2008
Results: Eighty patients (92%) had adenocarcinomas and 7 (8%) had squamous cell cancers. The clinical stage at diagnosis was IIA in 8 (9%), IIB in 7 (8%), III in 57 (66%), and IVA in 15 (17%) patients. The majority (85 [98%]) completed neoadjuvant chemotherapy and radiation that included 5-Fluorouracil and platinum-based chemotherapy with 4,500 to 5,040 cGy external beam radiation. Patients underwent surgery at a median of 7 days after PET-CT imaging. At the time of surgery, all 87 patients (100%) had negative margin resections. Sixty-four patients (74%) were found to have an overall down-stage at the time of surgery. The pathologic response was complete in 38 patients (44%). Twenty-three (26%) had microscopically viable disease while 26 (30%) had gross residual disease. The PET-CT response, measured as percentage SUV reduction, was highly correlated with pathologic response (p \ 0.0001). Specifically, patients with PET maximum SUV reductions of \25%, 25-\50%, 50-\75%, and .75% had a 10%, 14%, 53%, and 72%, respectively, had a chance of pathologic complete response. The T-category, N-category, and histology did not correlate with pathologic response (p = 0.72, p = 0.74, and p = 0.08, respectively). Conclusions: This large, single institution retrospective series suggests that FDG PET-CT response is highly correlated with pathologic response for patients with esophageal cancer undergoing neoadjuvant treatment with combined chemotherapy and radiation. Author Disclosure: D.A. Schomas, None; P.J. Peller, None; J.M. Donahue, None; F.C. Nichols, None; V. Lowe, None; J.F. Quevedo, None; R.C. Miller, None.
2184
A Prospective Evaluation of Lymph Node GTV Delineation by 18FDG PET/CT for Patients with Esophageal Cancer
X. L. Fu, W. Yu, Y. J. Zhang, J. Q. Xiang, G. L. Jiang Cancer Hospital of Fudan University, Shanghai, China Purpose/Objective(s): To find the optimal SUV threshold of diagnosing lymph node (LN) group metastasis in esophageal cancer and to prospectively evaluate the accuracy of LN GTV delineation with it. Materials/Methods: From May 2007 to Jan 2008, 16 patients with esophageal squamous cell carcinoma underwent contrast-enhanced chest CT and 18FDG PET/CT before radical esophagectomy and 3-field LN dissection. The LN groups were recorded according to the Akiyama LN map for esophageal cancer from Japan. A ROC curve of diagnosing LN group metastasis with different SUV thresholds was drawn to seek for the optimal threshold (SUVthre). The diagnostic values of PET/CT with SUVthre and CT for depiction of LN group metastasis were compared. Three LN GTVs were defined, one based on CT alone (GTVN1), one based on PET/CT with SUVthre (GTVN2), and another based on pathologic results (GTVN3, delineated on presurgical CT). The GTVN1 and GTVN2 were compared with GTVN3 by means of a conformity index (CI, the intersection of the two GTVNs divided by their union), e.g., CI1&3 = GTVN1&3/(GTVN1 + GTVN3 - GTVN1&3). Results: Of 16 patients, 2 had pT1 tumors, 6 pT2, 5 pT3 and 3 pT4, 10 pN0, and 6 pN1, 10 pM0, 0 pM1a, and 6 pM1b. A total of 144 LN groups (452 LNs) were dissected and 21groups (33 LNs) proved to be malignant at pathologic examination. The area under curve (AUC) of the ROC curve was 0.9017 and SUVthre was 2.36. For depiction of LN group metastasis, the sensitivity, specificity, and accuracy of PET/CT with 2.36 were 76.19%, 95.93%, and 93.06%, whereas those of CT were 33.33%, 94.31%, and 85.42% (p values: 0.0117, 0.7539, and 0.0266, respectively). The mean GTVN1, GTVN2, and GTVN3 were 1.52 ± 2.38, 2.82 ± 4.51, and 2.68 ± 4.16 cm3, respectively. The mean CI1&3 and CI2&3 were 0.31 and 0.65 (p value = 0.0352). Conclusions: The optimal SUV threshold of diagnosing LN group metastasis in esophageal cancer may be 2.36, at which the sensitivity and accuracy for PET/CT turned out to be superior to those for CT. Comparing to LN GTV based on CT, the one based on PET/CT was much better conformed to the real range of malignant LNs. Author Disclosure: X.L. Fu, None; W. Yu, None; Y.J. Zhang, None; J.Q. Xiang, None; G.L. Jiang, None.
2185
MRI and 4D-CT Minimum Intensity Projection Volumes in Patients undergoing Stereotactic Body Radiation Therapy for Hepatic Lesions
W. G. Rule, P. DeRose, T. Boike, S. Shaddock, R. Timmerman, A. Ramzi University of Texas Southwestern Medical Center, Dallas, TX Purpose/Objective(s): Liver metastases have long been a challenging problem for radiation oncologists. Multiple treatment modalities, including surgical resection, laser thermotherapy, cryosurgery, ethanol injection, intra-arterial chemotherapy, and radiofrequency ablation have all been employed with varying results. Stereotactic body radiation therapy (SBRT) is increasingly utilized in the treatment of hepatic metastases and primary hepatic tumors. One of the prerequisites for quality SBRT delivery is precise imaging definition of the tumor volume. The purpose of this study is to analyze the differences in contoured gross tumor volumes (GTV) between treatment planning MRI and 4D-CT minimum intensity projection reconstruction (MinIP) in patients undergoing hepatic SBRT. Materials/Methods: Patients undergoing SBRT of the liver at our center undergo the following procedures: All patients are immobilized in a stereotactic body frame. Abdominal compression is used to limit diaphragmatic motion to less than one centimeter. While in the treatment position, a 4D-CT (including MinIP reconstruction) and an MRI (typically T2 fat saturation sequences) are obtained. These scans are then fused with the planning CT using the liver contour. For this study, six sets of MRI and 4D-CT MinIP planning scans from 6 patients previously treated with SBRT for hepatic lesions (six total lesions, one primary and five metastatic) were utilized. New gross tumor volumes on each of the MRI and 4D-CT MinIP scans were independently contoured by a physician and the differences in their volumes were compared. Results: The group mean MRI volume was 127.08 cc (range, 3.04-450.53 cc) and the mean 4D-CT MinIP volume was 96.30 cc (range, 2.84-327.82 cc). The contoured MRI volumes were 1.22 (range, 1.00-1.37) times greater on average than the 4D-CT MinIP volumes. The mean percentage of the 4D-CT MinIP volume that was encompassed by the MRI volume was 88.20 (range, 77.1297.75). Conclusions: From this small cohort of patients it is apparent that the utilization of treatment planning MRI resulted in a significantly increased GTV as compared to a 4D-CT MinIP. This is in spite of the 4D-CT MinIP taking into account tumor motion. It was
S252
Volume 72, Number 1, Supplement, 2008
Results: Eighty patients (92%) had adenocarcinomas and 7 (8%) had squamous cell cancers. The clinical stage at diagnosis was IIA in 8 (9%), IIB in 7 (8%), III in 57 (66%), and IVA in 15 (17%) patients. The majority (85 [98%]) completed neoadjuvant chemotherapy and radiation that included 5-Fluorouracil and platinum-based chemotherapy with 4,500 to 5,040 cGy external beam radiation. Patients underwent surgery at a median of 7 days after PET-CT imaging. At the time of surgery, all 87 patients (100%) had negative margin resections. Sixty-four patients (74%) were found to have an overall down-stage at the time of surgery. The pathologic response was complete in 38 patients (44%). Twenty-three (26%) had microscopically viable disease while 26 (30%) had gross residual disease. The PET-CT response, measured as percentage SUV reduction, was highly correlated with pathologic response (p \ 0.0001). Specifically, patients with PET maximum SUV reductions of \25%, 25-\50%, 50-\75%, and .75% had a 10%, 14%, 53%, and 72%, respectively, had a chance of pathologic complete response. The T-category, N-category, and histology did not correlate with pathologic response (p = 0.72, p = 0.74, and p = 0.08, respectively). Conclusions: This large, single institution retrospective series suggests that FDG PET-CT response is highly correlated with pathologic response for patients with esophageal cancer undergoing neoadjuvant treatment with combined chemotherapy and radiation. Author Disclosure: D.A. Schomas, None; P.J. Peller, None; J.M. Donahue, None; F.C. Nichols, None; V. Lowe, None; J.F. Quevedo, None; R.C. Miller, None.
2184
A Prospective Evaluation of Lymph Node GTV Delineation by 18FDG PET/CT for Patients with Esophageal Cancer
X. L. Fu, W. Yu, Y. J. Zhang, J. Q. Xiang, G. L. Jiang Cancer Hospital of Fudan University, Shanghai, China Purpose/Objective(s): To find the optimal SUV threshold of diagnosing lymph node (LN) group metastasis in esophageal cancer and to prospectively evaluate the accuracy of LN GTV delineation with it. Materials/Methods: From May 2007 to Jan 2008, 16 patients with esophageal squamous cell carcinoma underwent contrast-enhanced chest CT and 18FDG PET/CT before radical esophagectomy and 3-field LN dissection. The LN groups were recorded according to the Akiyama LN map for esophageal cancer from Japan. A ROC curve of diagnosing LN group metastasis with different SUV thresholds was drawn to seek for the optimal threshold (SUVthre). The diagnostic values of PET/CT with SUVthre and CT for depiction of LN group metastasis were compared. Three LN GTVs were defined, one based on CT alone (GTVN1), one based on PET/CT with SUVthre (GTVN2), and another based on pathologic results (GTVN3, delineated on presurgical CT). The GTVN1 and GTVN2 were compared with GTVN3 by means of a conformity index (CI, the intersection of the two GTVNs divided by their union), e.g., CI1&3 = GTVN1&3/(GTVN1 + GTVN3 - GTVN1&3). Results: Of 16 patients, 2 had pT1 tumors, 6 pT2, 5 pT3 and 3 pT4, 10 pN0, and 6 pN1, 10 pM0, 0 pM1a, and 6 pM1b. A total of 144 LN groups (452 LNs) were dissected and 21groups (33 LNs) proved to be malignant at pathologic examination. The area under curve (AUC) of the ROC curve was 0.9017 and SUVthre was 2.36. For depiction of LN group metastasis, the sensitivity, specificity, and accuracy of PET/CT with 2.36 were 76.19%, 95.93%, and 93.06%, whereas those of CT were 33.33%, 94.31%, and 85.42% (p values: 0.0117, 0.7539, and 0.0266, respectively). The mean GTVN1, GTVN2, and GTVN3 were 1.52 ± 2.38, 2.82 ± 4.51, and 2.68 ± 4.16 cm3, respectively. The mean CI1&3 and CI2&3 were 0.31 and 0.65 (p value = 0.0352). Conclusions: The optimal SUV threshold of diagnosing LN group metastasis in esophageal cancer may be 2.36, at which the sensitivity and accuracy for PET/CT turned out to be superior to those for CT. Comparing to LN GTV based on CT, the one based on PET/CT was much better conformed to the real range of malignant LNs. Author Disclosure: X.L. Fu, None; W. Yu, None; Y.J. Zhang, None; J.Q. Xiang, None; G.L. Jiang, None.
2185
MRI and 4D-CT Minimum Intensity Projection Volumes in Patients undergoing Stereotactic Body Radiation Therapy for Hepatic Lesions
W. G. Rule, P. DeRose, T. Boike, S. Shaddock, R. Timmerman, A. Ramzi University of Texas Southwestern Medical Center, Dallas, TX Purpose/Objective(s): Liver metastases have long been a challenging problem for radiation oncologists. Multiple treatment modalities, including surgical resection, laser thermotherapy, cryosurgery, ethanol injection, intra-arterial chemotherapy, and radiofrequency ablation have all been employed with varying results. Stereotactic body radiation therapy (SBRT) is increasingly utilized in the treatment of hepatic metastases and primary hepatic tumors. One of the prerequisites for quality SBRT delivery is precise imaging definition of the tumor volume. The purpose of this study is to analyze the differences in contoured gross tumor volumes (GTV) between treatment planning MRI and 4D-CT minimum intensity projection reconstruction (MinIP) in patients undergoing hepatic SBRT. Materials/Methods: Patients undergoing SBRT of the liver at our center undergo the following procedures: All patients are immobilized in a stereotactic body frame. Abdominal compression is used to limit diaphragmatic motion to less than one centimeter. While in the treatment position, a 4D-CT (including MinIP reconstruction) and an MRI (typically T2 fat saturation sequences) are obtained. These scans are then fused with the planning CT using the liver contour. For this study, six sets of MRI and 4D-CT MinIP planning scans from 6 patients previously treated with SBRT for hepatic lesions (six total lesions, one primary and five metastatic) were utilized. New gross tumor volumes on each of the MRI and 4D-CT MinIP scans were independently contoured by a physician and the differences in their volumes were compared. Results: The group mean MRI volume was 127.08 cc (range, 3.04-450.53 cc) and the mean 4D-CT MinIP volume was 96.30 cc (range, 2.84-327.82 cc). The contoured MRI volumes were 1.22 (range, 1.00-1.37) times greater on average than the 4D-CT MinIP volumes. The mean percentage of the 4D-CT MinIP volume that was encompassed by the MRI volume was 88.20 (range, 77.1297.75). Conclusions: From this small cohort of patients it is apparent that the utilization of treatment planning MRI resulted in a significantly increased GTV as compared to a 4D-CT MinIP. This is in spite of the 4D-CT MinIP taking into account tumor motion. It was