Ultrasonographic splanchnic arterial flow measurement in severe acute pancreatitis

The role of Doppler sonography in predicting severity of acute pancreatitis

PURPOSE

To investigate the role of Doppler sonography (DUS) examination of major abdominal arteries in predicting severity of acute pancreatitis (AP).

METHODS

Twenty-nine patients diagnosed with AP and 14 controls were blindly and prospectively evaluated with Doppler sonography. Disease severity was defined clinically according to acute physiology and chronic health evaluation (APACHE II) score and was classified as severe for APACHE II score > or =8. DUS examination included the measurement of peak systolic velocity (PSV), end diastolic velocity (EDV), pulsatility index (PI), and resistance index (RI) of the celiac artery (CA) and superior mesenteric artery (SMA). Statistical analysis included Mann-Whitney U test, Student t test, and receiver operating characteristic curve analysis.

RESULTS

Twelve patients had severe AP and 17 had mild AP. PSV, EDV, and PI of the CA and RI of the SMA were higher in the severe AP group than in the mild AP and control groups (p < 0.001 and p < 0.0001, respectively). The sensitivity and specificity were 100% and 94%, respectively, for a 87 cm/second CA PSV cutoff value, 75% and 100%, respectively, for a 22 cm/second CA EDV cutoff value, 92% and 82%, respectively, for a 1.29 CA PI cutoff value, and 100% and 100%, respectively, for a 0.86 SMA RI cutoff value.

CONCLUSION

DUS can be useful in predicting the severity of AP in the early period of admission phase of the disease.

Sonographic assessment of splanchnic arteries and the bowel wall

The intestinal wall can be visualized using high resolution transabdominal ultrasound. The normal intestinal wall thickness in the terminal ileum, cecum, and right and left colon is <2mm when examined with graded compression. It is important to appreciate that a contracted intestinal segment can be misinterpreted as a thickened wall. Vascularisation can be mainly displayed in the second hyperechoic layer (submucosal layer) as well as vessels penetrating the muscularis propria. Imaging of the gastrointestinal wall is dependent on the experience of the examiner as well dependent on the equipment used. Acute or chronic inflammation of the intestinal wall is accompanied by increased perfusion of the mesentery, which can be displayed non-quantitatively with colour duplex. In contrast, ischemia is characterised by hypoperfusion of the mesenteric arteries and the bowel wall. The most promising sonographic approach in assessing splanchnic arteries and the bowel wall is combining the analysis of superior and inferior mesenteric inflow by pulsed Doppler scanning (systolic and diastolic velocities, resistance index) with the end-organ vascularity by colour Doppler imaging diminishing the influence of examination technique only displaying bowel wall vascularity. Colour Doppler imaging has been described as helpful in a variety of gastrointestinal disorders, particularly in patients with Crohn's disease, celiac disease, mesenteric artery stenosis and other ischemic gastrointestinal diseases, graft versus host disease and hemorrhagic segmental colitis.

A simple catheter-vessel model for MR assessment of drug distribution in arteries and optimization of catheter design for intraarterial infusion therapy

PURPOSE

To investigate the efficacy of a new catheter-vessel model for MRI to evaluate drug distribution and to optimize catheter design for intraarterial infusion therapy

MATERIALS AND METHODS

The model consisted of a hepatic artery simulant tube through which blood simulant water flowed continuously and a water cistern. Catheters were inserted into the tube and a gadolinium contrast medium was injected at rates suitable for angiographic or computed tomographic evaluation and commensurate with the clinical drug infusion rate. Axial images of the tube were obtained with a 0.2-T scanner and gradient echo technique. Preliminary studies and catheter tests were conducted. The points at which drug and water were completely mixed were defined as the site with uniform enhancement nearest the catheter tip.

RESULTS

Flip angle and gadolinium concentrations were optimized at 90 degrees, and at 62.5 and 500 mM for the high and low infusion rates, respectively. Drug distribution near the catheter tips was clearly visualized. The drug was mixed in shorter distances via the slit side-hole than the end- or side-hole catheters, and the smaller diametrical than the larger at either rate.

CONCLUSION

This model appeared to be effective for evaluation of drug distribution and optimization of catheter design.