title: Potentials and limitations of low-concentration contrast medium (150 mg iodine/ml) in CT pulmonary angiography.
abstract: OBJECTIVE
  To assess the feasibility of producing diagnostic multidetector computed tomography (MDCT) pulmonary angiography with low iodine concentration contrast media (150 mg iodine/ml) in patients with suspected acute pulmonary embolism.
  
  
  METHODS
  Ninety-five randomized patients underwent MDCT (64 row) pulmonary angiography with 100ml iopromide either at low concentration (LC) of 150 mg iodine/ml (n=45) or high concentration (HC) of 300 mg iodine/ml (n=50), delivered at the rate of 5 ml/s via a power injector. Two experienced radiologists, blinded to the concentration used, subjectively assessed the diagnostic quality and confidence using a four-point scale [1=poor (not diagnostic), 2=satisfactory, 3=good, 4=excellent]. Attenuation values (in HU) were measured in the main proximal branches of the pulmonary arteries.
  
  
  RESULTS
  The median diagnostic quality score for both observers was 3.5 (interquartile range 3-4) in the HC group and 2.5 (interquartile range 1.5-3) in the LC group (p<0.01). The median diagnostic confidence score for both observers was 4 (interquartile range 3-4) in the HC group and 3 (interquartile range 1.5-4) in the LC group (p<0.01). Both observers rated examinations as diagnostic in 69% of cases in the LC group, compared with 96% of cases in the HC group. Good interobserver agreement was found in both groups (K value 0.72 in the LC group and 0.73 in the HC). Obesity, poor scan timing, and dilution by venous return of non-opacified blood were the main reasons for a reduction in diagnostic quality of examinations in the LC group.
  
  
  CONCLUSIONS
  Despite a 50% reduction of contrast medium dose in comparison to the standard technique, 150 mg iodine/ml can produce diagnostic MDCT pulmonary angiogram studies in the absence of obesity or high cardiac output and hyper-dynamic pulmonary circulation. Reducing the dose of contrast media would minimize the risk of contrast nephropathy in patients at risk of this complication, particularly those suffering from congestive heart failure in whom intravenous hydration is contraindicated.
authors.affiliation: Department of diagnostic Imaging, Northern General Hospital, Sheffield, UK.
authors.forename: M R
authors.initials: MR
authors.lastname: Radon
authors.forename: M J
authors.initials: MJ
authors.lastname: Kaduthodil
authors.forename: J
authors.initials: J
authors.lastname: Jagdish
authors.forename: S
authors.initials: S
authors.lastname: Matthews
authors.forename: C
authors.initials: C
authors.lastname: Hill
authors.forename: M J
authors.initials: MJ
authors.lastname: Bull
authors.forename: S K
authors.initials: SK
authors.lastname: Morcos
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media / Q000008:administration & dosage; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007455:Iodine / Q000008:administration & dosage; D007472:Iohexol / Q000008:administration & dosage / Q000031:analogs & derivatives*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging* / Q000503:physiopathology; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide; D007455:Iodine