Comparison of three dimensional magnetic resonance imaging in conjunction with a blood pool contrast agent and nuclear scintigraphy for the detectionof experimentally induced gastrointestinal bleeding

Background and aims-To compare the performance of 3D magnetic resonance ima ging (MRT) in conjunction with an intravascular contrast agent with that of scintigraphy, with respect to detection and localisation of gastrointestin al haemorrhage in vivo in pigs. Methods-Intraluminal bleeding sites were surgically created in the small bo wel and colon of six pigs. The animals underwent scintigraphy with Tc-99m l abelled red blood cells and 3D MRI following administration of an intravasc ular contrast agent (NC100150) at five minute intervals over 30 minutes. Fo r analysis, the intestinal tract was divided into six segments. Based on th e two evaluated methods, each segment was characterised on a five point sca le regarding the presence of a bleed. At autopsy, the surgically manipulate d bowel segments were inspected for the presence of haemorrhage. Results-Bleeding was confirmed at autopsy in 18/36 segments. Contrast extra vasation with subsequent movement through the bowel could be documented on MRI data sets. All segments were correctly characterised, resulting in 100% sensitivity and specificity for MRI. Based on scintigraphy, interpretation of seven segments (19%) was false (sensitivity/specificity of 78%/72%). Di fferences in diagnostic performance were evident in the receiver operator c haracteristic (ROC) analysis, with an area under the MRI curve of 0.99 and under the scintigraphy curve of 0.85. Conclusion-in conjunction with an intravascular contrast agent, 3D MRI perm its accurate detection and localisation of gastrointestinal bleeding. The e xtent and evolution of intestinal bleeding can be determined with repeated data acquisition.