Quantification of Iliac Arterial Blood Velocity in Stenotic Phantom and Porcine Models Using Quantitative Digital Subtraction Angiography.

PURPOSE: To assess the feasibility of using quantitative digital subtraction angiography (qDSA) to quantify arterial velocity in phantom and porcine stenotic iliac artery models. MATERIALS AND METHODS: Varying stenoses (mild, <50%; moderate, 50%-70%; and severe, >70%) were created in a silicone iliac artery phantom using vessel loops. Two-dimensional digital subtraction angiographies (DSAs) were performed, with velocities calculated using qDSA. qDSA velocities were compared with flow rates and velocities measured with an ultrasonic flow probe. Two-dimensional DSAs of the common and external iliac arteries were then performed in 4 swine (mean weight, 63 kg) before and after a severe stenosis (>70%) was created in the iliac artery using 3-0 silk suture. Peak systolic velocities on pulsed wave Doppler ultrasound (US) before and after stenosis creation were correlated with the qDSA velocities. Pearson correlation, linear regression, and analysis of variance were used for analysis. RESULTS: In the phantom study, ultrasonic probe velocities positively correlated with downstream qDSA (r = 0.65; P < .001) and negatively correlated with peristenotic qDSA velocities (r = -0.80; P < .001). In the swine study, statistically significant reductions in external iliac arterial velocity were noted on US and qDSA after stenosis creation (P < .05). US and qDSA velocities strongly correlated for all flow states with both 50% and 100% contrast concentrations (r = 0.82 and r = 0.74, respectively), with an estimated US-to-qDSA ratio of 1.3-1.5 (P < .001). qDSA velocities with 50% and 100% contrast concentrations also strongly correlated (r = 0.78; P < .001). CONCLUSIONS: In both phantom and swine stenosis models, changes in iliac arterial velocity could be quantified with qDSA, which strongly correlated with standard-of-care US.

Presence of Portomesenteric Venous Gas and Pneumatosis Intestinalis in Nonocclusive Mesenteric Ischemia as a Complication of Transrectal Ultrasound-Guided Prostate Biopsy.

A 58-year-old man with a history of mechanical aortic valve replacement, on anticoagulation with warfarin, presented to the emergency department with hematochezia 1 day after undergoing transrectal ultrasound-guided prostate biopsy. On presentation, he was found to have hemorrhagic shock. Fluid resuscitation, packed red blood cell transfusion, and empiric antibiotic therapy were initiated, and the patient was admitted to an intensive care unit. Abdominal-pelvic computed tomography demonstrated portomesenteric venous gas and pneumatosis intestinalis. Colonoscopy showed ischemic ulcers at the ascending colon and stigmata of recent bleeding at the site of biopsy in the rectum, which was treated endoscopically. The patient was discharged after continued improvement during hospitalization. On follow-up, the patient continued to be symptom-free, and a repeat colonoscopy demonstrated healing colonic ulcers.