AIM:To explore the physiopathology and magnetic resonance imaging(MRI)findings in an animal model of acute arterial mesenteric ischemia(AAMI)with and without reperfusion.METHODS:In this study,8 adult Sprague-Dawley ra...AIM:To explore the physiopathology and magnetic resonance imaging(MRI)findings in an animal model of acute arterial mesenteric ischemia(AAMI)with and without reperfusion.METHODS:In this study,8 adult Sprague-Dawley rats underwent superior mesenteric artery(SMA)ligation and were then randomly divided in two groups of 4.In groupⅠ,the ischemia was maintained for 8 h.In groupⅡ,1-h after SMA occlusion,the ligation was removed by cutting the thread fixed on the back of the animal,and reperfusion was monitored for 8 h.MRI was performed using a 7-T system.RESULTS:We found that,in the case of AAMI without reperfusion,spastic reflex ileus,hypotonic reflex ileus,free abdominal fluid and bowel wall thinning are present from the second hour,and bowel wall hyperintensity in T2-W sequences are present from the fourth hour.The reperfusion model shows the presence of early bowel wall hyperintensity in T2-W sequences after 1 h and bowel wall thickening from the second hour.CONCLUSION:Our study has shown that MRI can assess pathological changes that occur in the small bowel and distinguish between the presence and absence of reperfusion after induced acute arterial ischemia.展开更多
AIM： To define the evolution of ischemic lesions with 7T magnetic resonance imaging （7T-MRI） in an animal model of acute colonic ischemia. METHODS： Adult Sprague-Dawley rats were divided into two groups. Group I u...AIM： To define the evolution of ischemic lesions with 7T magnetic resonance imaging （7T-MRI） in an animal model of acute colonic ischemia. METHODS： Adult Sprague-Dawley rats were divided into two groups. Group I underwent inferior mesenteric artery （IMA） ligation followed by macroscopic observa- tions and histological analysis. In group H, 7T-MRI was performed before and after IMA ligation and followed by histological analysis. RESULTS： Morphological alterations started to develop 1 h after IMA ligation, when pale areas became evident in the splenic flexure mesentery and progressively wors-ened up to 8 h thereafter, when the mesentery was less pale, and the splenic flexure loop appeared very dark. The 7T-MRI results reflected these alterations, showing a hyperintense signal in both the intraperitoneal space and the colonic loop wall 1 h after IMA ligation; the lat- ter progressively increased to demonstrate a reduction in the colonic loop lumen at 6 h. Eight hours after IMA ligation, MRI showed a persistent colonic mural hyper- intensity associated with a reduction in peritoneal free fluid. The 7T-MRI findings were correlated with histolog- ical alterations, varying from an attenuated epithelium with glandular apex lesions at 1 h to coagulative necro- sis and loss of the surface epithelium detected 8 h after IMA ligation. CONCLUSION： MRI may be used as a substitute for invasive procedures in diagnosing and grading acute ischemic colitis, allowing for the early identification of pathological findings.展开更多
文摘AIM:To explore the physiopathology and magnetic resonance imaging(MRI)findings in an animal model of acute arterial mesenteric ischemia(AAMI)with and without reperfusion.METHODS:In this study,8 adult Sprague-Dawley rats underwent superior mesenteric artery(SMA)ligation and were then randomly divided in two groups of 4.In groupⅠ,the ischemia was maintained for 8 h.In groupⅡ,1-h after SMA occlusion,the ligation was removed by cutting the thread fixed on the back of the animal,and reperfusion was monitored for 8 h.MRI was performed using a 7-T system.RESULTS:We found that,in the case of AAMI without reperfusion,spastic reflex ileus,hypotonic reflex ileus,free abdominal fluid and bowel wall thinning are present from the second hour,and bowel wall hyperintensity in T2-W sequences are present from the fourth hour.The reperfusion model shows the presence of early bowel wall hyperintensity in T2-W sequences after 1 h and bowel wall thickening from the second hour.CONCLUSION:Our study has shown that MRI can assess pathological changes that occur in the small bowel and distinguish between the presence and absence of reperfusion after induced acute arterial ischemia.
文摘AIM： To define the evolution of ischemic lesions with 7T magnetic resonance imaging （7T-MRI） in an animal model of acute colonic ischemia. METHODS： Adult Sprague-Dawley rats were divided into two groups. Group I underwent inferior mesenteric artery （IMA） ligation followed by macroscopic observa- tions and histological analysis. In group H, 7T-MRI was performed before and after IMA ligation and followed by histological analysis. RESULTS： Morphological alterations started to develop 1 h after IMA ligation, when pale areas became evident in the splenic flexure mesentery and progressively wors-ened up to 8 h thereafter, when the mesentery was less pale, and the splenic flexure loop appeared very dark. The 7T-MRI results reflected these alterations, showing a hyperintense signal in both the intraperitoneal space and the colonic loop wall 1 h after IMA ligation; the lat- ter progressively increased to demonstrate a reduction in the colonic loop lumen at 6 h. Eight hours after IMA ligation, MRI showed a persistent colonic mural hyper- intensity associated with a reduction in peritoneal free fluid. The 7T-MRI findings were correlated with histolog- ical alterations, varying from an attenuated epithelium with glandular apex lesions at 1 h to coagulative necro- sis and loss of the surface epithelium detected 8 h after IMA ligation. CONCLUSION： MRI may be used as a substitute for invasive procedures in diagnosing and grading acute ischemic colitis, allowing for the early identification of pathological findings.
