MR imaging in patients with Crohn disease: value of T2- versus T1-weighted gadolinium-enhanced MR sequences with use of an oral superparamagnetic contrast agent.
OBJECTIVE
To prospectively compare oral contrast-enhanced T2-weighted half-Fourier rapid acquisition with relaxation enhancement (RARE) magnetic resonance (MR) imaging with T1-weighted gadolinium-enhanced fast low-angle shot (FLASH) MR and standard examinations in the evaluation of Crohn disease.


METHODS
Institutional review board approval and informed consent were obtained. Fifty-nine patients with Crohn disease underwent MR imaging after oral administration of a superparamagnetic contrast agent; RARE plain and fat-suppressed sequences and FLASH sequences were performed before and after intravenous injection of gadolinium chelate. References were endoscopic, small-bowel barium, computed tomographic, ultrasonographic, and clinical-biochemical scoring of disease activity. Two radiologists analyzed MR images for presence and extent of Crohn disease lesions, presence of strictures or other complications, and degree of local inflammation. MR findings were correlated with endoscopic, radiologic, and clinical data (kappa statistic and Spearman rank correlation test).


RESULTS
T2-weighted MR was 95% accurate, 98% sensitive, and 78% specific for detection of ileal lesions. Agreement between T1- and T2-weighted images ranged from 0.77 for ileal lesions to 1.00 for colic lesions. T2-weighted MR enabled detection of 26 of 29 severe strictures, 17 of 24 enteroenteric fistulas, and all adhesions and abscesses; T1-weighted MR enabled detection of 20 of 29 severe strictures, 16 of 24 enteroenteric fistulas, and all adhesions and abscesses. Complications leading to surgery were found in 12 (20%) patients; these were assessed correctly with either T1- or T2-weighted images. T2-weighted signal intensities of the wall and mesentery correlated with biologic activity (P < .001, r of 0.774 and 0.712, respectively). Interobserver agreement was 0.642-1.00 for T2-weighted and 0.711-1.00 for T1-weighted images.


CONCLUSIONS
T2-weighted MR can depict Crohn disease lesions and help assess mural and transmural inflammation with the same accuracy as gadolinium-enhanced T1-weighted MR. Combination of gadolinium-enhanced T1- and T2-weighted sequences is useful in the assessment of Crohn disease.
Maccioni
Francesca
F
Department of Radiological Sciences, Clinical Sciences, Gastroenterology Unit, and Surgical Sciences, University of Rome La Sapienza, Via Regina Elena 324, 00161 Rome, Italy. francesca.maccioni@uniroma1.it
Bruni
Antonio
A
Viscido
Angelo
A
Colaiacomo
Maria Chiara
MC
Cocco
Andrea
A
Montesani
Chiara
C
Caprilli
Renzo
R
Marini
Mario
M
D000293:Adolescent; D000328:Adult; D000368:Aged; D003287:Contrast Media; D003424:Crohn Disease / Q000175:diagnosis*; D005260:Female; D052203:Ferrosoferric Oxide; D019786:Gadolinium DTPA; D006801:Humans; D007501:Iron; D008279:Magnetic Resonance Imaging / Q000379:methods; D058185:Magnetite Nanoparticles; D008297:Male; D008875:Middle Aged; D010087:Oxides; D011446:Prospective Studies; D012833:Siloxanes
D003287:Contrast Media; D058185:Magnetite Nanoparticles; D010087:Oxides; D012833:Siloxanes; C088769:ferumoxsil; D007501:Iron; D019786:Gadolinium DTPA; D052203:Ferrosoferric Oxide