The role of computed tomography in the diagnostic pathway of acute mesenteric ischemia: a nested case-control study.

BACKGROUND: Computed tomography (CT) can be used as the primary screening modality for the evaluation of patients suspected of having acute mesenteric ischemia known to show high sensitivity and specificity rates. PURPOSE: To prove the value of CT in patients with pathological abdominal findings following cardiac surgery. MATERIAL AND METHODS: In a retrospective case-control study, 12 different CT scan parameters of patients with or without mesenteric ischemia following cardiac surgery were compared using univariate and logistic regression analyses. RESULTS: Of 14,176 patients, 133 (0.9%) received an abdominal CT scan during postoperative care due to pathological abdominal findings. Sixty-eight patients were diagnosed with acute mesenteric ischemia. In-hospital mortality was 73.5% for this group. CT parameters with the highest specificity for indicating colonic ischemia were intestinal (99%) or porto-venous (96%) pneumatosis, abnormal contrast medium enhancement (89%), and occlusion of the proximal inferior mesenteric artery (81%). All of those parameters showed low sensitivity levels in the range of 15%-23%. A statistically significant association between acute mesenteric ischemia and CT appearance was obtained for contrast medium enhancement (odds ratio [OR] 12.2, 95% confidence interval [CI] 1.5-99.2) and intestinal pneumatosis (OR 21.0, 95% CI 2.7-165.2) only. CONCLUSION: The typical CT criteria indicating mesenteric ischemia lose their accuracy in patients under critical clinical conditions. As CT remains the first-line diagnostic imaging modality for abnormal abdominal findings following cardiac surgery, negative signs should not prevent early laparotomy if clinical suspicion remains high.

Bowel Ischemia in ICU Patients: Diagnostic Value of I-FABP Depends on the Interval to the Triggering Event.

BACKGROUND: Intestinal fatty acid-binding protein (I-FABP) has been shown to be of high diagnostic value in patients with acute mesenteric ischemia. Whether these results can be reproduced in critically ill patients on the ICU was to be investigated. MATERIALS AND METHODS: I-FABP was measured in serum and urine of 43 critically ill patients in ICU when mesenteric ischemia was suspected. Bowel ischemia was confirmed in 21 patients (group 1). 22 patients who survived at least seven days without confirmation of ischemia were assigned to group 2. I-FABP levels were compared between the groups, and interval from the event that has triggered ischemia to I-FABP measurement was recorded. RESULTS: For the identification of patients with mesenteric ischemia, sensitivity, specificity, and area under the curve (AUC) for serum and urine I-FABP were 33.3%, 95.5%, and 0.565 and 81.3%, 70.0%, and 0.694, respectively. I-FABP measurements performed within 12 to 48 h after the event that triggered ischemia showed a sensitivity, specificity, and AUC for serum and urine of 75%, 100%, and 0.853 and 100%, 73.3%, and 0.856, respectively. CONCLUSIONS: In ICU patients, one single I-FABP measurement at the time of clinical suspicion failed to reliably detect or exclude mesenteric ischemia. A higher diagnostic value of I-FABP was only confirmed in the early stages of mesenteric ischemia. I-FABP may be used most appropriately in perioperative monitoring.

Multimodal imaging of aortoiliac occlusive disease with three-dimensional postprocessing of PET angiography and CT.

Two patients with aortoiliac occlusive disease underwent dynamic and late-static positron emission tomography/computed tomography (PET/CT) acquisitions with 257 and 244 MBq F-18 FDG (CT scan parameters 50 mAs, 120 kV, pitch 1.25). Three-dimensional reconstructions revealed an occluded aortic stent and a high-grade aortic stenosis and demonstrated the relations of vascular pathologies to adjacent structures. Early-dynamic PET can be performed without additional radioactive tracer and may be valuable for evaluation and intervention planning in patients with contraindications to other angiographic modalities.

In vivo assessment of the hepatic microcirculation after mesenterico-portal bypass (REX-shunt) using orthogonal polarization spectral imaging.

BACKGROUND: Extrahepatic portal vein thrombosis, not associated with cirrhosis or tumours, is the second most frequent cause of portal hypertension worldwide. Especially in children, anatomic mesenterico-portal interposition (REX-shunt) has become an established treatment. The changes in hepatic microcirculation after reperfusion of the shunt have not been investigated so far. AIMS: This study investigates the hepatic microcirculation before and after REX-shunt interposition using orthogonal polarization spectral imaging (OPS). PATIENTS AND METHODS: Since 2004, three consecutive patients with extrahepatic portal vein thrombosis underwent REX-shunt interposition. We measured the hepatic microcirculation by OPS before and directly after REX-shunt reperfusion and analysed the capillary vessel diameter, red blood cell velocity, functional capillary density and volumetric blood flow. Furthermore, we compared our values with the physiological values of the hepatic microcirculation defined previously by other investigators. RESULTS: All shunts showed an excellent function in the follow-up investigations. The intra-individual microcirculatory analysis revealed a reduction in the red blood cell velocity after shunt reperfusion in particular. CONCLUSIONS: Our results provide preliminary evidence for the reversal of the hepatic arterial buffer response following the restoration of the portal venous blood flow. This may be a short-term effect because of the restored portal venous blood flow.