title: Feasibility of spectral imaging with low-concentration contrast medium in abdominal CT angiography of obese patients.
abstract: OBJECTIVE
  To explore the application value of dual-energy spectral imaging scanning with low radiation dose and low-concentration contrast medium (270 mg I/mL) in abdominal CT angiography (CTA) of obese patients.
  
  
  METHODS
  A total of 127 obese patients (BMI≥25 kg/m(2) and waist circumference ≥900 mm) referred for abdominal CTA were prospectively enrolled in the study. The patients were divided into two groups; in group A (n=69), a spectral imaging scan mode and 270 mg I/mL iodine concentration contrast medium was used, and in group B (n=58), a conventional imaging scan mode using 120 kVp and 350 mg I/mL iodine concentration contrast medium was used. The image quality of the right renal artery in the two groups was evaluated by two observers using a 5-point scale, and the scores were compared using the Mann-Whitney U-test; the inter-observer agreement for the scores was analysed using the Kappa test. The CT values of the abdominal aorta, the superior mesenteric artery, the common hepatic artery and the splenic artery, and the CT value and standard deviation (SD) of the erector spinae at the level of the right renal hilum in groups A and B were measured by two observers; the inter-observer agreement of the measurement data was analysed using the inter-class correlation coefficient test. The following parameters were compared between the two groups using an independent sample t-test: the CT values of the abdominal aorta and its main branches; the image contrast-to-noise ratio (CNR) and figure of merit (FOM) of the abdominal aorta; the CT dose index (CTDIvol ); the dose length product (DLP); and the total iodine intake of the patients. P<.05 suggested a statistically significant difference.
  
  
  RESULTS
  The image scores of the right renal artery in groups A (4.59±0.60) and B (4.53±0.63) were the same (P=.57), with good inter-observer agreement. The CT values of the abdominal aorta, the superior mesenteric artery, the common hepatic artery and the splenic artery were >300 HU in both the groups; there was no statistically significant difference between the two groups (all P>.05), and inter-observer agreement was also good. Group A had significantly higher CNR and FOM values in the abdominal aorta than group B (all P<.001). Compared with group B, the CTDIvol and DLP values in group A were decreased by 46% and 35%, respectively. The total iodine intake for patients in group A was 27 g, 23% lower than the 35 g intake for patients in group B.
  
  
  CONCLUSIONS
  Compared with conventional CT, spectral CT imaging significantly reduces both radiation dose and contrast dose while maintaining image quality in abdominal CTA for patients with central obesity and high BMI.
authors: Department of Radiology, First Affiliated Hospital of Dalian Medical University, Dalian, China.
authors: Yijun
authors: Y
authors: Liu
authors: Department of Radiology, First Affiliated Hospital of Dalian Medical University, Dalian, China.
authors: Ailian
authors: A
authors: Liu
authors: Department of Radiology, First Affiliated Hospital of Dalian Medical University, Dalian, China.
authors: Lei
authors: L
authors: Liu
authors: Department of Radiology, First Affiliated Hospital of Dalian Medical University, Dalian, China.
authors: Shifeng
authors: S
authors: Tian
authors: Department of Radiology, First Affiliated Hospital of Dalian Medical University, Dalian, China.
authors: Jinghong
authors: J
authors: Liu
authors: Department of Radiology, First Affiliated Hospital of Dalian Medical University, Dalian, China.
authors: Renwang
authors: R
authors: Pu
authors: Department of Radiology, First Affiliated Hospital of Dalian Medical University, Dalian, China.
authors: Xin
authors: X
authors: Fang
authors: Department of Radiology, First Affiliated Hospital of Dalian Medical University, Dalian, China.
authors: Xiaofeng
authors: X
authors: Liu
authors: Department of Radiology, First Affiliated Hospital of Dalian Medical University, Dalian, China.
authors: Gang
authors: G
authors: Yuan
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging; D000072226:Computed Tomography Angiography / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage*; D005240:Feasibility Studies; D006499:Hepatic Artery / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D017538:Mesenteric Artery, Superior / Q000000981:diagnostic imaging; D008875:Middle Aged; D009765:Obesity / Q000150:complications / Q000000981:diagnostic imaging*; D011860:Radiography, Abdominal / Q000379:methods; D012077:Renal Artery / Q000000981:diagnostic imaging; D013157:Splenic Artery / Q000000981:diagnostic imaging
chemical_list: D003287:Contrast Media