Ultrasound Assessment of the Mesenteric Arteries

Duplex ultrasound in the early diagnosis of acute mesenteric ischemia: a longitudinal cohort multicentric study

OBJECTIVE

Acute mesenteric ischemia (AMI) is a life-threatening condition requiring time-dependent treatment; thus, early recognition may improve outcomes. We hypothesized that clinician-performed mesenteric vessels duplex ultrasound (DUS) could facilitate early identification of patients with AMI in high-risk patients presenting with abdominal pain.

METHODS

This was a single-operator, observational, prospective cohort study. Patients aged at least 65 presenting to Emergency Departments with acute abdominal pain and no clear diagnosis after an initial work-up were enrolled. All patients underwent multidetector computed tomography and these findings provided the reference standard in this study. DUS of the celiac artery and superior mesenteric artery (SMA) were obtained to measure the peak systolic velocity (PSV) and were performed within 24 h of admission. PSVs outside the normal range were considered to indicate AMI.

RESULTS

Of 49 patients identified, 47 were consented to enrollment and diagnostic images were obtained in 45 (96%). Fifteen patients (33%) had AMI (six occlusive, nine nonocclusive disease). Among these, 12 (80%) had abnormal DUS velocities. SMA PSV showed a sensitivity of 78.57% [95% confidence interval (CI): 49.2-95.34], a specificity of 64.52% (95% CI: 45.37-80.77), a positive predictive value of 50% (95% CI: 28.22-71.78), and a negative predictive value of 86.96% (95% CI: 66.41-97.22) for AMI. DUS had a sensitivity of 100%, a specificity of 64%, and a negative predictive value of 100% for occlusive AMI. Assessment of celiac artery PSV did not improve diagnostic performance.

CONCLUSION

In this single-operator pilot study, mesenteric vessel DUS was performed successfully in the Emergency Department, with a high proportion of diagnostic images obtained. A normal SMA PSV was associated with a low risk of occlusive AMI.

An anatomically detailed arterial network model for one-dimensional computational hemodynamics

Simulation platforms are increasingly becoming complementary tools for cutting-edge cardiovascular research. The interplay among structural properties of the arterial wall, morphometry, anatomy, wave propagation phenomena, and ultimately, cardiovascular diseases continues to be poorly understood. Accurate models are powerful tools to shed light on these open problems. We developed an anatomically detailed computational model of the arterial vasculature to conduct 1-D blood flow simulations to serve as simulation infrastructure to aid cardiovascular research. An average arterial vasculature of a man was outlined in 3-D space to serve as geometrical substrate for the mathematical model. The architecture of this model comprises almost every arterial vessel acknowledged in the medical/anatomical literature, with a resolution down to the luminal area of perforator arteries. Over 2000 arterial vessels compose the model. Anatomical, physiological, and mechanical considerations were employed for the set up of model parameters and to determine criteria for blood flow distribution. Computational fluid dynamics was used to simulate blood flow and wave propagation phenomena in such arterial network. A sensitivity analysis was developed to unveil the contributions of model parameters to the conformation of the pressure waveforms. In addition, parameters were modified to target model to a patient-specific scenario. On the light of the knowledge domain, we conclude that the present model features excellent descriptive and predictive capabilities in both patient-generic and patient-specific cases, presenting a new step toward integrating an unprecedented anatomical description, morphometric, and simulations data to help in understanding complex arterial blood flow phenomena and related cardiovascular diseases.

Mesenteric/celiac duplex ultrasound interpretation criteria revisited

BACKGROUND

Several published studies with a small sample size have reported differing results of duplex ultrasound (DUS) utilizing different threshold velocities in detecting significant stenosis of superior mesenteric (SMA) or celiac arteries (CA). The present study is based on the largest number of mesenteric duplex/angiography correlations reported to date for the diagnosis of SMA/CA stenosis.

METHODS

One hundred fifty-three patients (151 SMA and 150 CA) had both DUS and arteriography. Receiver operator curves (ROC) were used to analyze peak systolic velocity (PSV), end diastolic velocity (EDV), and SMA or CA/aortic PSV ratio in detecting ≥50% and ≥70% stenosis.

RESULTS

For SMA (151 arteries: 84 with ≥50% stenosis [54 of which had ≥70% stenosis] based on angiography): the PSV threshold that provided the highest overall accuracy (OA) for detecting ≥50% SMA stenosis was ≥295 cm/s (sensitivity [sens.] 87%, specificity [spec.] 89%, and OA 88%); and for detecting ≥70% SMA, it was ≥400 cm/s (sens. 72%, spec. 93%, and OA 85%). The EDV threshold that provided the highest OA for detecting ≥50% stenosis was ≥45 cm/s (sens. 79%, spec. 79%, and OA 79%); and for ≥70% stenosis was ≥70 cm/s (sens. 65%, spec. 95%, and OA 84%). ROC analysis showed that PSV was better than EDV and SMA/aortic PSV ratio for ≥50% stenosis of SMA (P = .003 and P = .0005). For celiac arteries (150 arteries: 105 with ≥50% stenosis [62 of which had ≥70% stenosis]): the PSV threshold that provided the highest OA for ≥50% stenosis was ≥240 cm/s (sens. 87, spec. 83%, and OA 86%); and for ≥70% stenosis was ≥320 cm/s (sens. 80%, spec. 89%, and OA 85%). The EDV threshold that provided the highest OA for ≥50% stenosis was ≥40 cm/s (sens. 84%, spec. 48%, and OA 73%); and for ≥70% stenosis was ≥100 cm/s (sens. 58%, spec. 91%, and OA 77%). ROC analysis showed that PSV was better than EDV and SMA/aortic PSV ratio for ≥50% stenosis of CA (P < .0001 and P = .0410.)

CONCLUSIONS

PSV values can be used in detecting ≥50% and ≥70% SMA/CA stenosis and were better than EDVs and ratios. Previously published data must be validated in individual vascular laboratories. Our results will need prospective validation.

Doppler sonographic criteria for the diagnosis of inferior mesenteric artery stenosis

OBJECTIVE

The purpose of this study was to define the optimal Doppler criteria for the diagnosis of inferior mesenteric artery (IMA) stenosis in patients with suspected chronic mesenteric ischemia (CMI).

METHODS

A retrospective review of 205 dedicated color and pulsed Doppler sonographic studies of mesenteric arteries was performed in 205 patients. All studies were performed in patients with suspected CMI. Correlative angiography was available in 50 patients.

RESULTS

The IMA was visualized in 176 of 205 Doppler sonographic examinations (86%) and in 92% of the correlative studies. The visualization rate for the detection of a patent IMA by Doppler sonography in this series was 90%. The ranges of the peak systolic velocity (PSV), end-diastolic velocity (EDV), and mesenteric-aortic velocity ratio (MAR) in the nonstenotic IMA were 70 to 200 cm/s, 0 to 33 cm/s, and 0.7 to 3.7, respectively. The ranges of the PSV, EDV, and MAR in IMA stenosis were 200 to 485 cm/s, 0 to 177 cm/s, and 0.69 to 8.1. The threshold values for severe IMA stenosis by logistic regression analysis (n = 42) were as follows: PSV, greater than 200 cm/s; EDV, greater than 25 cm/s; and MAR, greater than 2.5, with sensitivities of 90%, 40%, and 80%; specificities of 97%, 91%, and 88%; positive predictive values (PPVs) of 90%, 57%, and 67%; negative predictive values (NPVs) of 97%, 83%, and 93%; and accuracy of 95%, 79%, and 86%, respectively.

CONCLUSIONS

We found that a PSV of greater than 200 cm/s was the best criterion for the diagnosis of IMA stenosis. The sensitivity, specificity, PPV, NPV, and accuracy for the PSV were 90%, 97%, 90%, 97%, and 95%, respectively.