title: CT of the pancreas: comparison of anatomic structure depiction, image quality, and radiation exposure between 320-detector volumetric images and 64-detector helical images.
abstract: OBJECTIVE
  To prospectively compare 320-detector volumetric and 64-detector helical computed tomographic (CT) images of the pancreas for depiction of anatomic structures, image noise, and radiation exposure.
  
  
  METHODS
  This study was approved by the institutional review board, and written informed consent was obtained. A total of 154 patients (85 men, 69 women; age range, 26-85 years; mean age, 67 years) who underwent biphasic (arterial and pancreatic phase) contrast material-enhanced CT performed with a 320-detector scanner were randomized into two groups: the 320-detector group and the 64-detector group. Biphasic transaxial multiplanar reformatted images and volume-rendered CT angiograms were obtained. CT numbers in the abdominal aorta, pancreas, and abdominal wall fat tissue; signal-to-noise ratio (SNR); and dose-length product (DLP) were compared. In addition, image quality and focal lesion depiction (n = 35) were qualitatively determined in the two groups. Unpaired t and Mann-Whitney tests were used for quantitative and qualitative assessment, respectively.
  
  
  RESULTS
  No significant difference in CT numbers of the abdominal aorta and pancreas was noted between the two groups. Mean DLP was 43% lower in the 320-detector group (675.4 mGy·cm) than in the 64-detector group (1187.8 mGy·cm) (P < .001). SNR of the abdominal aorta, pancreas, and abdominal wall fat on biphasic images was significantly lower in the 320-detector group than in the 64-detector group (P < .001). Image quality was acceptable in both groups and was slightly better in the 64-detector group for pancreatic phase axial images (P = .02) and arterial phase multiplanar reformatted images (P < .01). No significant difference was found in the depiction of pancreatic parenchyma, main pancreatic duct, focal pancreatic lesions, splanchnic arteries, or most of the small splanchnic arterial branches.
  
  
  CONCLUSIONS
  A 320-detector CT scan facilitates fast volumetric contrast-enhanced CT of the entire pancreas with acceptable image quality, even though SNR was significantly lower at 320-detector volumetric scanning.
authors.affiliation: Department of Radiology, Gifu University School of Medicine, 1-1 Yanagido, Gifu 501-1193, Japan. gossy@par.odn.ne.jp
authors.forename: Satoshi
authors.initials: S
authors.lastname: Goshima
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kanematsu
authors.forename: Hironori
authors.initials: H
authors.lastname: Nishibori
authors.forename: Kota
authors.initials: K
authors.lastname: Sakurai
authors.forename: Daisuke
authors.initials: D
authors.lastname: Miyazawa
authors.forename: Haruo
authors.initials: H
authors.lastname: Watanabe
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kondo
authors.forename: Yoshimune
authors.initials: Y
authors.lastname: Shiratori
authors.forename: Minoru
authors.initials: M
authors.lastname: Onozuka
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Moriyama
authors.forename: Kyongtae T
authors.initials: KT
authors.lastname: Bae
mesh_terms: D000328:Adult; D000368:Aged; D001822:Body Burden; D003287:Contrast Media; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007472:Iohexol; D008297:Male; D008875:Middle Aged; D010182:Pancreatic Diseases / Q000000981:diagnostic imaging*; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods; D011874:Radiometry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol