[Abdominal pain of vascular cause]

MRI for the Detection of Small Bowel Ischemic Injury in Arterial Acute Mesenteric Ischemia: Preclinical Study in a Porcine Model

BACKGROUND

MRI is the reference for the diagnosis of arterial cerebral ischemia, but its role in acute mesenteric ischemia (AMI) is poorly known.

PURPOSE

To assess MRI detection of early ischemic bowel lesions in a porcine model of arterial AMI.

STUDY TYPE

Prospective/cohort.

ANIMAL MODEL

Porcine model of arterial AMI obtained by embolization of the superior mesenteric artery (seven pigs).

FIELD STRENGTH/SEQUENCE

A 5-T. T1 gradient-echo-weighted-imaging (WI), half-Fourier-acquisition-single-shot-turbo-spin-echo, T2 turbo-spin-echo, true-fast-imaging-with-steady-precession (True-FISP), diffusion-weighted-echo-planar (DWI).

ASSESSMENT

T1-WI, T2-WI, and DWI were performed before and continuously after embolization for 6 hours. The signal intensity (SI) of the ischemic bowel was assessed visually and quantitatively on all sequences. The apparent diffusion coefficient (ADC) was assessed.

STATISTICAL TESTS

Paired Student's t-test or Mann-Whitney U-test, significance at P < 0.05.

RESULTS

One pig died from non-AMI-related causes. The remaining pigs underwent a median 5 h53 (range 1 h24-6 h01) of ischemia. Visually, the ischemic bowel showed signal hyperintensity on DWI-b800 after a median 85 (57-276) minutes compared to the nonischemic bowel. DWI-b800 SI significantly increased after 2 hours (+19%) and the ADC significant decrease within the first hour (-31%). The ischemic bowel was hyperintense on precontrast T1-WI after a median 87 (70-171) minutes with no significant quantitative changes over time (P = 0.46-0.93). The ischemic bowel was hyperintense on T2-WI in three pigs with a significant SI increase on True-FISP after 1 and 2 hours.

DATA CONCLUSION

Changes in SI and ADC can be seen early after the onset of arterial AMI with DWI. The value of T2-WI appears to be limited.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 2.