Hm. Klein et al., CT AND MRI OF EXPERIMENTALLY-INDUCED MESENTERIC ISCHEMIA IN A PORCINEMODEL, Journal of computer assisted tomography, 20(2), 1996, pp. 254-261
Objective: Our goal was to assess the value of CT and MRI for the dete
ction of bowel wall changes in experimentally induced mesenteric ische
mia, Methods: In 18 female pigs, a percutaneous embolization of the su
perior mesenteric artery was performed with buthyl-2-cyanoacrylate and
Lipiodol (1:1) (experimental group). In six animals, only diagnostic
imaging and histologic evaluation were performed (control group). CT w
as carried out 3, 6, and 12 h after occlusion. Incremental CT (1 s sca
n time, 5 mm slice thickness, 7 mm increment, 120 kV/290 mAs) and spir
al CT (slice thickness 5 mm, pitch 1.5, 120 kV/165 mA) were performed
pre and post contrast injection (Somatom Plus/Siemens). Serial CT was
carried out after intravenous contrast injection (1 ml/kg, 2 ml/s). MR
I (Magnetom 1.5 T; Siemens) was performed with T1 (pre and post 0.01 m
mol/kg Gd-DTPA; Magnevist; Schering, Germany), T2, and proton density
images in axial orientation. Slice thickness was 3 mm and slice gap 1
mm. Additionally, a TI-weighted GE sequence (multislice FLASH 2D) was
obtained in dynamic technique (before and 30, 60, and 90 s after contr
ast agent injection) with a slice thickness of 5 mm. Biometrical monit
oring included blood pressure, heart frequency, blood cell count, elec
trolyte status, blood gas analysis, and determination of serum lactate
, Image evaluation included morphological analysis and determination o
f the enhancement pattern. Histological specimens were obtained and an
alyzed according to the Chiu classification. Results: The histologic w
orkup of the specimen 3, 6, and 12 h after vascular occlusion revealed
an average Chiu state 3, 4, and 5, On CT, the bowel wall had a thickn
ess of 4.7 mm on average in the ischemic segments. There was a signifi
cant difference from the control group (average 3 mm), Free intraperit
oneal fluid and intramural gas were seen after 12 h of ischemia in 80%
. In ischemic bowel segments, no mural enhancement was seen. Normal se
gments and the bowel of the control animals showed an enhancement of 3
4 PIU on average (SD = 3.1 HU; p < 0.01). In MRI, S/N and C/N differed
significantly between experimental and control groups in T1 and proto
n density images. In ischemic segments of all phases, the bowel wall d
id not show contrast enhancement. Healthy segments and bowel of contro
l animals showed a significant enhancement (p < 0.01). Conclusion: Cro
ss-sectional imaging has a high sensitivity for delineation of ischemi
c bowel wall segments. The enhancement pattern of the bowel wall enabl
es detection of location, extent, and cause of a acute arterial mesent
eric ischemia with high accuracy in an early phase.