Magnetization transfer ratio for the assessment of perianal fistula activity in Crohn's disease.

OBJECTIVES: Assessment of perianal fistulas is important to guide management of Crohn's disease (CD). Our objectives were to analyze the feasibility of magnetization transfer (MT) imaging to assess fistulas and to evaluate its contribution in assessing disease activity. METHODS: During 15 months, all patients referred for perianal fistulas in CD underwent 3T-MRI including diffusion, T2/T1-weighted gadolinium-enhanced sequences and MT sequences (one with an off-resonance saturation pulse of 800 and one with 1200 Hz). We collected Van Assche score, fistula activity signs by analyzing T2, diffusion and contrast enhancement. We calculated MT ratio (MTR) with a ROI in the largest fistula. RESULTS: Twenty-nine patients (mean 34.9 years, range 17-53) were included. Van Assche score was 11.7, range 4-21. In 22 patients, the fistula presented with a bright T2 and diffusion signal with contrast enhancement, and was characterized as active. Mean MTR was respectively 47.2 (range 12-68) and 34.3 (range 11-57) at 800 and 1200 Hz. MTR at 800 Hz was significantly lower in non-active (34, range 12-55) than in active fistulas (51, range 24-68) (p < 0.02). CONCLUSIONS: MTR is feasible for the assessment of fistulas in CD and in the future could be used to help identify active and non-active fistulas. KEY POINTS: • MTR is feasible for the assessment of perianal fistulas in CD. • MT allows quantitative imaging of perianal fistula activity in CD. • MTR could be used to help identify active and non-active fistulas in CD.

Comparison of enhancement of the vestibular perilymph between gadoterate meglumine and gadobutrol at 3-Tesla in Meniere's disease.

PURPOSE: To compare the degree of enhancement of the perilymph between two macrocyclic gadolinium-based contrast agents (gadobutrol and gadoterate meglumine) in patients with Meniere's disease at 3-T magnetic resonance imaging (MRI). MATERIALS AND METHODS: The MRI examinations of 20 patients with Meniere's disease obtained 4hours after a single intravenous dose of macrocyclic gadolinium-based contrast agents were retrospectively compared. Ten patients (median age: 58.5 years; median body mass index [BMI]: 25) have received a single intravenous dose of gadoterate meglumine and 10 patients (median age: 45.5 years; median BMI: 25.4) have received a single-dose of gadobutrol. Two radiologists independently measured the signal intensity ratio (SIR) by using region of interest analysis and performed a visual assessment in order to evaluate the perilymph of each semicircular canal and of the vestibule. RESULTS: No differences in SIR of the symptomatic ear were found between gadobutrol (median SIR: 1.58) and gadoterate meglumine (median SIR: 1.3) (P=0.18). The SIR of the contralateral asymptomatic ear was significantly greater with gadobutrol (median: 1.62) than with gadoterate meglumine (median: 1.21) (P=0.009). No differences in endolymphatic structures visualization were found between gadobutrol and gadoterate meglumine in the symptomatic ears (P=0.27) but gadobutrol allowed a better assessment of endolymphatic structures and semicircular canals in the asymptomatic ear (P<0.001). CONCLUSION: Gadobutrol and gadoterate meglumine provide similar degrees of enhancement of the symptomatic ear in patients with Meniere's disease but gadobutrol provides better anatomical details regarding endolymphatic space and semicircular canals of asymptomatic, contralateral ear.