title: Low-dose multidetector CT angiography in the evaluation of infrarenal aorta and peripheral arterial occlusive disease.
abstract: OBJECTIVE
  To investigate the ionizing radiation dose, image quality, and diagnostic performance of computed tomographic (CT) angiography of the peripheral arteries with three different CT angiographic acquisition protocols, with use of pretreatment digital subtraction angiography (DSA) as the reference standard.
  
  
  METHODS
  The study was approved by the institutional review board and performed in agreement with the 1990 Declaration of Helsinki and subsequent amendments. Each patient provided informed consent before undergoing CT. The authors performed a prospective, single-center, randomized comparison of three different x-ray exposure CT acquisition protocols in 60 randomized patients with peripheral arterial occlusive disease referred for 64-section multidetector CT angiography of the lower limb (0.625-mm collimation, intravenous administration of 100 mL of iomeprol [400 mg iodine per milliliter] at 4 mL/sec). The acquisition protocols were performed with (a) 120 kVp and a noise index of 26 (moderate noise reduction [MNR]), referred to as the 120-kVp MNR group; (b) 80 kVp and a noise index of 26, referred to as the 80-kVp MNR group; and (c) 80 kVp and a noise index of 30 (high noise reduction [HNR]), referred to as the 80-kVp HNR group. Axial and three-dimensional (3D) images were qualitatively and quantitatively compared by using the overall F test and pairwise comparisons. The X(2) test was used to compare the three protocols in terms of diagnostic performance in patients who also underwent DSA before an interventional procedure.
  
  
  RESULTS
  Significantly higher attenuation values were obtained in the vessels with the 80-kVp MNR and 80-kVp HNR acquisition protocols. No significant differences were noted in terms of image quality with either axial source images or 3D reconstructions. Likewise, no significant differences were found among the three protocols in terms of noise throughout the peripheral vasculature. Finally, no significant differences were found among the three groups with regard to diagnostic performance. Overall dose reductions of 48% and 61% were obtained for the 80-kVp MNR and 80-kVp HNR protocols, respectively.
  
  
  CONCLUSIONS
  Substantial reductions of radiation dose are achievable at multidetector CT angiography of the peripheral arteries without compromising image quality and diagnostic performance if acquisition protocols are modified appropriately and used in conjunction with a contrast material containing a high concentration of iodine.
authors.affiliation: Department of Bioimaging and Radiological Sciences, Institute of Radiology, A. Gemelli Hospital-Catholic University, L.go A Gemelli 8, 00168 Rome, Italy. roberto.iezzi@rm.unicatt.it
authors.forename: Roberto
authors.initials: R
authors.lastname: Iezzi
authors.forename: Marco
authors.initials: M
authors.lastname: Santoro
authors.forename: Riccardo
authors.initials: R
authors.lastname: Marano
authors.forename: Carmine
authors.initials: C
authors.lastname: Di Stasi
authors.forename: Roberta
authors.initials: R
authors.lastname: Dattesi
authors.forename: Miles
authors.initials: M
authors.lastname: Kirchin
authors.forename: Giovanni
authors.initials: G
authors.lastname: Tinelli
authors.forename: Francesco
authors.initials: F
authors.lastname: Snider
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Bonomo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015901:Angiography, Digital Subtraction / Q000379:methods*; D001018:Aortic Diseases / Q000000981:diagnostic imaging*; D001157:Arterial Occlusive Diseases / Q000000981:diagnostic imaging*; D016009:Chi-Square Distribution; D003287:Contrast Media; D005260:Female; D006801:Humans; D007479:Iopamidol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D016491:Peripheral Vascular Diseases / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; C057937:iomeprol; D007479:Iopamidol