title: Aerosol deposition in the lungs of spontaneously breathing rats using Gd-DOTA-based contrast agents and ultra-short echo time MRI at 1.5 Tesla.
abstract: OBJECTIVE
  Aerosol toxicology and drug delivery through the lungs, which depend on various parameters, require methods to quantify particle deposition. Intrapulmonary-administered MRI contrast agent combined with lung-specific imaging sequences has been proposed as a high performance technique for aerosol research. Here, aerosol deposition is assessed using ultra-short echo (UTE) sequences.
  
  
  METHODS
  Before and after administration of Gd-DOTA-based aerosol delivered nose-only in free-breathing healthy rats, a T1 -weighted 3D UTE sequence was applied in a clinical 1.5 Tesla scanner. Administration lasted 14 min, and the experiment was performed on six rats. A contrast-enhanced quantitative analysis was done.
  
  
  RESULTS
  Fifty percent signal enhancement was obtained in the lung parenchyma. Lung clearance of the contrast agent was evaluated to be 14% per h (corresponding to a characteristic clearance time of 3.6 h) and aerosol deposition was shown to be homogeneous throughout the lung in healthy rats. The total deposited dose was estimated to be 1.05 µmol/kg body weight, and the concentration precision was 0.02 mM.
  
  
  CONCLUSIONS
  The UTE protocol with nebulized Gd-DOTA is replicable to significantly enhance the lung parenchyma and to map aerosol deposition. This functional strategy, applied in a clinical system with a clinical nebulization setup and a low inhaled dose, suggests a feasible translation to human.
authors: Imagerie par Résonance Magnétique Médicale et Multi-Modalités (UMR8081), IR4M, Univ. Paris-Sud, CNRS, Orsay, France.
authors: Hongchen
authors: H
authors: Wang
authors: Imagerie par Résonance Magnétique Médicale et Multi-Modalités (UMR8081), IR4M, Univ. Paris-Sud, CNRS, Orsay, France.
authors: Catherine
authors: C
authors: Sebrié
authors: Imagerie par Résonance Magnétique Médicale et Multi-Modalités (UMR8081), IR4M, Univ. Paris-Sud, CNRS, Orsay, France.
authors: Jean-Pierre
authors: JP
authors: Ruaud
authors: Imagerie par Résonance Magnétique Médicale et Multi-Modalités (UMR8081), IR4M, Univ. Paris-Sud, CNRS, Orsay, France.
authors: Geneviève
authors: G
authors: Guillot
authors: Imagerie par Résonance Magnétique Médicale et Multi-Modalités (UMR8081), IR4M, Univ. Paris-Sud, CNRS, Orsay, France.
authors: Khaoula
authors: K
authors: Bouazizi-Verdier
authors: Imagerie par Résonance Magnétique Médicale et Multi-Modalités (UMR8081), IR4M, Univ. Paris-Sud, CNRS, Orsay, France.
authors: Georges
authors: G
authors: Willoquet
authors: Imagerie par Résonance Magnétique Médicale et Multi-Modalités (UMR8081), IR4M, Univ. Paris-Sud, CNRS, Orsay, France.
authors: Xavier
authors: X
authors: Maître
authors: Imagerie par Résonance Magnétique Médicale et Multi-Modalités (UMR8081), IR4M, Univ. Paris-Sud, CNRS, Orsay, France.
authors: Luc
authors: L
authors: Darrasse
authors: Imagerie par Résonance Magnétique Médicale et Multi-Modalités (UMR8081), IR4M, Univ. Paris-Sud, CNRS, Orsay, France.
authors: Ludovic
authors: L
authors: de Rochefort
mesh_terms: D000280:Administration, Inhalation; D000281:Administration, Intranasal; D000336:Aerosols; D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage*; D005240:Feasibility Studies; D006571:Heterocyclic Compounds / Q000008:administration & dosage*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008168:Lung / Q000033:anatomy & histology*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D009942:Organometallic Compounds / Q000008:administration & dosage*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000336:Aerosols; D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C050823:gadolinium 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetate
keywords: Gd-DOTA; aerosol deposition; contrast enhancement; lung MRI; nebulization; ultra-short echo