title: The effectiveness of gadolinium MRI to improve target delineation for radiotherapy in hepatocellular carcinoma: a comparative study of rigid image registration techniques.
abstract: To achieve consistent target delineation in radiotherapy for hepatocellular carcinoma (HCC), image registration between simulation CT and diagnostic MRI was explored. Twenty patients with advanced HCC were included. The median interval between MRI and CT was 11 days. CT was obtained with shallow free breathing and MRI at exhale phase. On each CT and MRI, the liver and the gross target volume (GTV) were drawn. A rigid image registration was taken according to point information of vascular bifurcation (Method[A]) and pixel information of volume of interest only including the periphery of the liver (Method[B]) and manually drawn liver (Method[C]). In nine cases with an indefinite GTV on CT, a virtual sphere was generated at the epicenter of the GTV. The GTV from CT (VGTV[CT]) and MRI (VGTV[MR]) and the expanded GTV from MRI (V+GTV[MR]) considering geometrical registration error were defined. The underestimation (uncovered V[CT] by V[MR]) and the overestimation (excessive V[MR] by V[CT]) were calculated. Through a paired T-test, the difference between image registration techniques was analyzed. For method[A], the underestimation rates of VGTV[MR] and V+GTV[MR] were 16.4 ± 8.9% and 3.2 ± 3.7%, and the overestimation rates were 16.6 ± 8.7% and 28.4 ± 10.3%, respectively. For VGTV[MR] and V+GTV[MR], the underestimation rates and overestimation rates of method[A] were better than method[C]. The underestimation rates and overestimation rates of the VGTV[MR] were better in method[B] than method[C]. By image registration and additional margin, about 97% of HCC could be covered. Method[A] or method[B] could be recommended according to physician preference.
authors.affiliation: Department of Radiation Oncology, Guro Hospital, College of Medicine, Korea University, Seoul, Republic of Korea.
authors.forename: D S
authors.initials: DS
authors.lastname: Yang
authors.affiliation: Department of Radiation Oncology, Ansan Hospital, College of Medicine, Korea University, Ansan, Republic of Korea. Electronic address: irionyws@korea.ac.kr.
authors.forename: W S
authors.initials: WS
authors.lastname: Yoon
authors.affiliation: Department of Radiation Oncology, Guro Hospital, College of Medicine, Korea University, Seoul, Republic of Korea.
authors.forename: J A
authors.initials: JA
authors.lastname: Lee
authors.affiliation: Department of Radiation Oncology, Anam Hospital, College of Medicine, Korea University, Seoul, Republic of Korea.
authors.forename: N K
authors.initials: NK
authors.lastname: Lee
authors.affiliation: Department of Radiation Oncology, Anam Hospital, College of Medicine, Korea University, Seoul, Republic of Korea.
authors.forename: S
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Radiation Oncology, Anam Hospital, College of Medicine, Korea University, Seoul, Republic of Korea.
authors.forename: C Y
authors.initials: CY
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Ansan Hospital, College of Medicine, Korea University, Ansan, Republic of Korea.
authors.forename: H J
authors.initials: HJ
authors.lastname: Yim
authors.affiliation: Department of Radiology, Ansan Hospital, College of Medicine, Korea University, Ansan, Republic of Korea.
authors.forename: S H
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Department of Radiology, Ansan Hospital, College of Medicine, Korea University, Ansan, Republic of Korea.
authors.forename: H H
authors.initials: HH
authors.lastname: Chung
authors.affiliation: Department of Radiology, Ansan Hospital, College of Medicine, Korea University, Ansan, Republic of Korea.
authors.forename: S H
authors.initials: SH
authors.lastname: Cha
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D005188:False Negative Reactions; D005240:Feasibility Studies; D005260:Female; D005682:Gadolinium; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008113:Liver Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D061089:Radiotherapy, Image-Guided; D014057:Tomography, X-Ray Computed
chemical_list: D005682:Gadolinium
keywords: Gross target volume; Hepatocellular carcinoma; Image registration; Radiotherapy