title: CT enterography at 80 kVp with adaptive statistical iterative reconstruction versus at 120 kVp with standard reconstruction: image quality, diagnostic adequacy, and dose reduction.
abstract: OBJECTIVE
  The objective of our study was to evaluate the image quality and diagnostic adequacy of the following two CT enterography protocols in patients weighing less than 160 lb (72 kg): 80-kVp imaging with the adaptive statistical iterative reconstruction (ASIR) in comparison with 120-kVp imaging with the filtered back projection reconstruction.
  
  
  METHODS
  We retrospectively reviewed 133 CT enterography examinations of 127 patients weighing less than 160 lb, 64 80-kVp examinations, and 69 120-kVp examinations. Image quality for evaluation of the bowel wall, mesenteric vessels, and hepatic parenchyma and the overall image quality were graded on a scale of 1-5 (1 = poor, 2 = acceptable, 3 = good, 4 = very good, 5 = excellent). Diagnostic accuracy for the detection of inflammatory bowel disease was evaluated. The volume CT dose index (CTDI(vol)) was recorded and effective dose was calculated from scanner-generated dose-length product.
  
  
  RESULTS
  There was a statistically significant decrease in the mean image quality scores for 80-kVp examinations compared with 120-kVp examinations for evaluation of the bowel wall (3.19 vs 3.70, respectively) and liver (3.12 vs 3.81) and for overall image quality (3.23 vs 3.68), but there was no significant decrease in score for evaluation of the mesenteric vessels (3.63 vs 3.67). None of the 80-kVp examinations was graded as poor, and all were considered to be of acceptable quality. Both techniques had comparable diagnostic accuracy for the detection of inflammatory bowel disease. Interobserver agreement was fair to moderate for qualitative image grading and was substantial for the detection of features of inflammatory bowel disease. The mean CTDI(vol) and effective dose for the 80-kVp examinations were 6.15 mGy and 4.60 mSv, respectively, and for the 120-kVp examinations, 20.79 mGy and 15.81 mSv.
  
  
  CONCLUSIONS
  In patients weighing less than 160 lb, CT enterography examinations at 80 kVp with 30% ASIR produce diagnostically acceptable image quality with an average CTDI(vol) of 6.15 mGy and an average effective dose of 4.60 mSv.
authors.affiliation: Department of Radiology, University of Michigan Hospitals, Ann Arbor, 48109-5030, USA. ravikaza@med.umich.edu
authors.forename: Ravi K
authors.initials: RK
authors.lastname: Kaza
authors.forename: Joel F
authors.initials: JF
authors.lastname: Platt
authors.forename: Mahmoud M
authors.initials: MM
authors.lastname: Al-Hawary
authors.forename: Ashish
authors.initials: A
authors.lastname: Wasnik
authors.forename: Peter S
authors.initials: PS
authors.lastname: Liu
authors.forename: Amit
authors.initials: A
authors.lastname: Pandya
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001835:Body Weight; D003287:Contrast Media; D005260:Female; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000000981:diagnostic imaging*; D007472:Iohexol / Q000031:analogs & derivatives; D007479:Iopamidol; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D011860:Radiography, Abdominal / Q000379:methods*; D011874:Radiometry; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide; D007479:Iopamidol