Reperfusion in non-occlusive mesenteric ischaemia (NOMI): effectiveness of CT in an emergency setting.

OBJECTIVE: To investigate the CT features of reperfusion (presence/absence) in non-occlusive mesenteric ischaemia (NOMI) and their prognostic value in an emergency setting. METHODS: A revision was undertaken of imaging from 20 patients (16 males/4 females) with a dismissal summary of NOMI. All patients had previously undergone a minimum of one multidetector CT examination, and consequently underwent surgery (n = 8), autopsy (n = 2), angiography (n = 1) or endoscopy (n = 9). An evaluation of the CT scans was conducted to determine vessels, mesentery, bowel and peritoneal cavity features. The superior mesenteric artery (SMA) average diameter of NOMI cases were compared with 30 controlled cases. Kappa, Kolmogorov-Smirnov (K-S) and Fisher's exact tests were used for statistical analysis. RESULTS: A mean SMA diameter significantly smaller than that of the controlled cases was found for patients with NOMI (K-S test: D = 0.75, p = 3.7 × 10-08). Fisher's exact tests showed a strong connection between the presence of reperfusion and mesenteric fat stranding (p = 0.026), bowel wall thickening (p = 3.2 × 10-05) and a high attenuation of the bowel wall on unenhanced CT images (p = 2.8 × 10-04). A reduction in mortality was significantly linked to the combination of normal mesenteric vessels and wall thickening (p = 0.034). CONCLUSION: Analysis of not only vessels findings but also mesentery and bowel CT features will support the identification of NOMI with or without a reperfusion event in an emergency setting. A strong correlation between some CT features and lower mortality exists. ADVANCES IN KNOWLEDGE: CT features of NOMI with or without reperfusion are demonstrated. Correctly assessing the presence of reperfusion in NOMI, may allow better management of these conditions in the emergency setting.

Differences in perfusion CT parameter values with commercial software upgrades: a preliminary report about algorithm consistency and stability.

BACKGROUND: Computed tomographic perfusion (CTp) imaging is a promising technique that allows functional imaging, as an adjunct to a morphologic CT examination, that can be used as an aid to carefully evaluate the response to therapy in oncologic patients. Considering this statement, it could be desirable that the measurements obtained with the CT perfusion software, and their upgrades, are consistent and reproducible. PURPOSE: To determine how commercial software upgrades impact on algorithm consistency and stability among the three version upgrades of the same platform in a preliminary study. MATERIAL AND METHODS: Blood volume (BV), blood flow (BF), mean transit time (MTT), and permeability surface area product (PS) were calculated with repeated measurements (n = 1119) while truncating the time density curve at different time values in six CT perfusion studies using CT perfusion software version 4D (CT Perfusion 4D), then repeated with the previous version (CT Perfusion 3.0 and CT Perfusion 4.0), using a fixed ROI both for arterial input and target lesion. The software upgrades were compared in pairs by applying a Kolmogorov-Smirnov test to all the parameters measured. Stability and reliability of the three versions were verified through the variation of the truncated parameters. RESULTS: The three software versions provided different parent distributions for approximately 80% of the 72 parameters measured. A complete agreement was found only for one patient in version 3.0 vs. 4.0 and 3.0 vs. 4D. Perfusion 4.0 vs. 4D: a complete agreement was found only in two cases. Parameters obtained with Perfusion 4D always showed the lowest standard deviation in all temporal intervals and also for all individual parameters. CONCLUSION: The three versions of the same platform tested yield different perfusion measurements. Thus, our preliminary results show that Perfusion 4D version uses a stable deconvolution algorithm to provide more reliable measurements.

Magnetic resonance imaging: is there a role in clinical management for acute ischemic colitis?

AIM: To validate the utility of magnetic resonance imaging (MRI) for the clinical management of acute ischemic colitis (IC). METHODS: This is a magnetic resonance (MR) prospective evaluation of 7 patients who were proved to have acute IC on the basis of clinical, endoscopic and computed tomography (CT) findings and who were imaged in our institution between February 2011 and July 2012. The mean age of the patients was 72.28 years. Abdominal CTs were obtained using a 64-detector row configuration for all patients with un-enhanced and contrast-enhanced scans, in the late arterial phase (start delay 45-50 s) and in the portal venous phase (start delay 70-80 s). The MR examinations were performed using a 1.5T superconducting magnet, using Fast Imaging Employing Steady State Acquisition and T2-weighted fast-recovery fast-spin echo sequences in axial and coronal plane. CT and MRI examinations were analysed for the presence of colonic abnormalities and associated findings. RESULTS: Segmental involvement was seen in 6 patients (85.71%), with a mean length of involvement of 412 mm (range 145.5-1000 mm). Wall thickness varied between 6 mm and 17.5 mm (mean 10.52 mm) upon CT examinations and from 5 to 15 mm (mean 8.8 mm) upon MR examinations. The MRI appearance of the colonic wall varied over the time: Type I appearance with a 3 layer sandwich sign was seen in 5 out of 12 examinations (41.66%), patients underwent MR within a mean of 36 h (ranging from 1 to 54 h) after the CT examination. Type II and III appearance with a 2 layer sign, was seen in 4 examinations (33.33%), patients underwent MR within a mean of 420.5 h (ranging from 121 to 720 h) after the CT examination. In the remaining three MRI examinations, performed within a mean of 410 h (ranging from 99.5 to 720 h) the colonic wall appeared normal. CONCLUSION: MRI, only using precontrast images, may be used as a substitute for invasive procedures in diagnosis and follow-up of acute IC.

Computed tomographic evaluation of mesentery: diagnostic value in acute mesenteric ischemia.

OBJECTIVE: To evaluate the computed tomographic appearances of mesentery in acute mesenteric ischemia (AMI) to recognize characteristic features and their prognostic values. METHODS: Computed tomographic examinations of 34 patients with a confirmed diagnosis of AMI were retrospectively reviewed to evaluate the number of mesenteric vessels, diameter of the superior mesenteric artery and superior mesenteric vein, mesenteric fat stranding, mesenteric vessel pneumatosis and ascites. RESULTS: Overall, at least one of these mesenteric signs was present in all but 1 patient. In all AMI of arterial occlusive type and in 68% of nonocclusive mesenteric ischemia, the number of arterial vessels was reduced (P = 0.067). Mesenteric vessel pneumatosis and reduced number of venous vessels were significantly associated with higher mortality (P = 0.027 and P = 0.042, respectively). Reperfusion signs were associated with a reduced mortality (28.7% vs 65.5%). CONCLUSION: Considering its characteristic features and its possible prognostic value, the evaluation of mesentery will supply additional information in the interpretation of computed tomography in AMI.