title: Preliminary experience with superparamagnetic iron oxide-enhanced dynamic magnetic resonance imaging and comparison with contrast-enhanced computed tomography in endoleak detection after endovascular aneurysm repair.
abstract: OBJECTIVE
  Contrast-enhanced computed tomography (CE-CT) has been commonly used for follow-up imaging after endovascular aneurysm repair (EVAR), but it is difficult to use on patients with renal insufficiency. Superparamagnetic iron oxide (SPIO) particles, contrast medium for magnetic resonance imaging (MRI) that has been widely used for detection of the liver tumor, rarely affects renal function. The present study examined SPIO-enhanced dynamic MRI as a potential alternative to CE-CT for detection of endoleaks after EVAR.
  
  
  METHODS
  Institutional review board approval was obtained for this prospective study. Twenty-three consecutive patients with normal renal function were evaluated using both CE-CT and SPIO-enhanced MRI within 2 weeks after EVAR. The median interval between the two modalities was 2 days. SPIO-enhanced MRI was performed at 1.5 T with T1-weighted, SPIO-enhanced dynamic, and postcontrast T1-weighted gradient echo sequences. The CE-CT protocol consisted of triple scans. Two experienced, blinded observers evaluated all images. Consensus reading of CE-CT and SPIO-MRI was defined as the reference standard. Interobserver, intraobserver, and intermodality agreement for endoleak detection was assessed by κ statistics.
  
  
  RESULTS
  A total of 11 type II endoleaks originating from either the lumbar or inferior mesenteric artery were detected. Eight were able to be detected by CE-CT (8/11:73%) and 10 (10/11:91%) by SPIO-enhanced MRI. Interobserver (κ = 0.91; 95% CI, 0.74-1.00) and intraobserver agreement for MRI (κ = 1.00) were excellent. Intermodality agreement for endoleak detection was moderate (κ = 0.63; 95% CI, 0.32-0.94; and κ = 0.62; 95% CI, 0.29-0.95 for observers A and B, respectively).
  
  
  CONCLUSIONS
  SPIO-enhanced MRI could represent a useful alternative to CE-CT, as it offers excellent interobserver, intraobserver agreement, and could detect more endoleaks than CE-CT.
authors.affiliation: Department of Radiology, Nara Medical University, Nara, Japan. shigeoichihashi@yahoo.co.jp
authors.forename: Shigeo
authors.initials: S
authors.lastname: Ichihashi
authors.forename: Nagaaki
authors.initials: N
authors.lastname: Marugami
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Tanaka
authors.forename: Shinichi
authors.initials: S
authors.lastname: Iwakoshi
authors.forename: Norio
authors.initials: N
authors.lastname: Kurumatani
authors.forename: Satoru
authors.initials: S
authors.lastname: Kitano
authors.forename: Akihiro
authors.initials: A
authors.lastname: Nogi
authors.forename: Kimihiko
authors.initials: K
authors.lastname: Kichikawa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017544:Aortic Aneurysm, Abdominal / Q000601:surgery*; D001027:Aortography / Q000379:methods*; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects*; D003287:Contrast Media; D003911:Dextrans; D057867:Endoleak / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000209:etiology; D057510:Endovascular Procedures / Q000009:adverse effects*; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D058185:Magnetite Nanoparticles; D008297:Male; D015588:Observer Variation; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; C065507:ferumoxides