title: Shoulder MR arthrography: in vitro determination of optimal gadolinium dilution as a function of field strength.
abstract: OBJECTIVE
  To find the optimal contrast agent dilution to maximize signal intensity (SI), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) in shoulder MR arthrography using MR systems operating at different magnetic field strengths.
  
  
  METHODS
  Autoptic human glenohumeral ligaments were inserted in eight egg-shaped 20-mL phantoms filled with saline and gadolinium diethylenetriaminepentaacetic acid bismethylamide (Gd-DTPA-BMA) in different dilutions of 0.5, 1, 2, 2.5, 5, 12.5, 50 mmol/liter, to simulate the shoulder articular capsule. These phantoms were inserted inside two plastic 240-mL phantoms filled with water. MRI was performed on 0.2-, 0.5-, 1.0-, 1.5-, and 3.0-T MR systems using a three-dimensional gradient echo (GRE)-T1-weighted pulse sequence. SI, SNR, and CNR were determined.
  
  
  RESULTS
  Peak SI and SNR were found at 5 mmol/liter, with the exception of the 0.2-T scanner, where the maximum was at 2 mmol/liter. Peak CNR was observed at 1 mmol/liter for the 3-T scanner, at 2 mmol/liter for the 0.2- and 0.5-T scanners, and at 5 mmol/liter for the remaining scanners.
  
  
  CONCLUSIONS
  The optimal SI and SNR are provided by 5 mmol/liter contrast agent dilution. Peak CNR was found in a range between 1 and 5 mmol/liter dilutions, depending on the strength of the magnetic field.
authors.affiliation: Radiology Department, Maggiore della Carità Hospital, Eastern Piedmont University, Novara, Italy. astecco@sirm.org
authors.forename: Alessandro
authors.initials: A
authors.lastname: Stecco
authors.forename: Marco
authors.initials: M
authors.lastname: Brambilla
authors.forename: Anna M A
authors.initials: AM
authors.lastname: Puppi
authors.forename: Marta
authors.initials: M
authors.lastname: Lovisolo
authors.forename: Renzo
authors.initials: R
authors.lastname: Boldorini
authors.forename: Alessandro
authors.initials: A
authors.lastname: Carriero
mesh_terms: D000704:Analysis of Variance; D002102:Cadaver; D003287:Contrast Media / Q000008:administration & dosage*; D019786:Gadolinium DTPA / Q000008:administration & dosage*; D006801:Humans; D008023:Ligaments, Articular / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D012782:Shoulder
chemical_list: D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA