title: The cisterna chyli: enhancement on delayed phase MR images after intravenous administration of gadolinium chelate.
abstract: OBJECTIVE
  To retrospectively evaluate cisterna chyli (CC) enhancement on magnetic resonance (MR) images obtained after intravenous administration of a gadolinium-based contrast agent.
  
  
  METHODS
  This retrospective HIPAA-compliant study of 1.5-T MR imaging findings was institutional review board approved; informed patient consent was waived. All MR examinations involved the acquisition of heavily T2-weighted single-shot fast spin-echo (SSFSE) images and three-dimensional (3D) gradient-echo images obtained before and during the arterial, venous, and 3-5-minute delayed phases after intravenous bolus injection of gadopentetate dimeglumine. Included were the data of 59 patients (37 men, 22 women; mean age, 59 years) who had a CC 4 mm or greater in transverse diameter, which was identified as a tubular structure with fluid signal intensity (SI) on SSFSE images. The SI of the CC relative to the spinal canal (SC) was noted and was measured on 3D gradient-echo images obtained during all phases. The Student t test was performed for statistical evaluations.
  
  
  RESULTS
  Mean CC-SC SI ratios on nonenhanced, arterial phase, venous phase, and delayed phase images were 0.92, 0.98, 0.99, and 2.13, respectively. The CC had low SI on all 3D gradient-echo images obtained during the nonenhanced, arterial, and venous phases and high SI, similar to the azygos vein SI, on all delayed phase images. The CC-SC SI ratio during the delayed phase was significantly higher than that during the other phases (P<.001).
  
  
  CONCLUSIONS
  The CC has minimal or no enhancement on arterial phase and venous phase images but intense enhancement--similar to the enhancement of veins--on delayed phase images. Comparison of delayed phase images with SSFSE and venous phase images may help to distinguish the CC seen on delayed phase images from lymph nodes, the azygos vein, or esophageal varices.
authors.affiliation: Department of Radiology, Thomas Jefferson University Hospital, 132 S 10th St, 1094 Main Bldg, Philadelphia, PA 19107, USA.
authors.forename: Sachit K
authors.initials: SK
authors.lastname: Verma
authors.forename: Donald G
authors.initials: DG
authors.lastname: Mitchell
authors.forename: Diane
authors.initials: D
authors.lastname: Bergin
authors.forename: Rashi
authors.initials: R
authors.lastname: Mehta
authors.forename: Sheetal
authors.initials: S
authors.lastname: Chopra
authors.forename: Dongil
authors.initials: D
authors.lastname: Choi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007275:Injections, Intravenous; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013897:Thoracic Duct / Q000033:anatomy & histology*
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA