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Capillary Hemorrhage Induced by Contrast-Enhanced Diagnostic Ultrasound in Rat Intestine
Xiaofang Lu1, Chunyan Dou1, Mario L Fabiilli1
1Department of Radiology, University of Michigan Health System, Ann Arbor, MI, USA.
Insights
Contrast-enhanced diagnostic ultrasound (CEDUS) can cause intestinal microvascular injury. Petechiae formation in rat intestines increased with longer intervals between ultrasound pulses and higher output power, indicating a potential risk.
Area of Science:
- Medical Imaging
- Ultrasound Bioeffects
- Vascular Biology
Background:
- Contrast-enhanced diagnostic ultrasound (CEDUS) utilizes microbubbles, which can induce cavitational bioeffects.
- Previous studies in the 1990s raised concerns about intestinal microvascular hemorrhage risk from ultrasound exposure.
- CEDUS is increasingly used for intestinal inflammation monitoring, necessitating updated risk assessments.
Purpose of the Study:
- To re-evaluate the risk of intestinal microvascular hemorrhage from diagnostic ultrasound imaging simulating CEDUS.
- To investigate the relationship between ultrasound parameters and the incidence of petechial hemorrhage in the intestine.
Main Methods:
- Anesthetized rats underwent abdominal scanning using a 1.6 MHz phased array probe during simulated Definity contrast agent infusion.
- Ultrasound output power and trigger intervals (2s to 10s) were systematically varied to assess dose-response.
- Petechiae counts in intestinal mucosa and muscle layers were quantified, and occult blood was tested.
Main Results:
- Intestinal petechiae counts significantly increased with longer trigger intervals, suggesting slow microvascular refill.
- Petechiae formation was observed to increase with output power exceeding a threshold of 1.4 MPa peak rarefactional pressure.
- Hemorrhage was noted in Peyer's patches, and occult blood was detected in multiple intestinal segments.
Conclusions:
- Diagnostic ultrasound imaging simulating CEDUS can induce microvascular injury and hemorrhage in the rat intestine.
- The risk of hemorrhage is dependent on ultrasound parameters, including trigger interval and output power.
- Findings align with earlier studies, underscoring the need for careful parameter selection during CEDUS examinations.
Abstract:
Contrast-enhanced diagnostic ultrasound (CEDUS) can lead to microvascular injury and petechial hemorrhage by the cavitational mechanism of ultrasonic bioeffects. Capillary hemorrhage has been noted in the heart and kidney, which are common targets of CEDUS examination. CEDUS has also become useful for monitoring intestinal inflammation. In the 1990s, the risk of intestinal microvascular hemorrhage was investigated both for incidental exposure by lithotripter shockwaves and for contrast agent microbubbles acting as cavitation nuclei with laboratory pulsed ultrasound systems. This study was initiated to update the risk assessment for intestine exposed to diagnostic imaging simulating CEDUS. The abdomens of anesthetized rats were scanned by a 1.6 MHz phased array probe during infusion of microbubble suspensions simulating Definity ultrasound contrast agent. Dual image frames were triggered intermittently, and the output power was varied to assess the exposure response. Petechiae counts in small intestine mucosa and muscle layers increased with increasing trigger interval from 2 s to 10 s, indicative of a slow refill after microbubble destruction. The counts increased with increasing output above a threshold of 1.4 MPa peak rarefactional pressure amplitude. Petechiae were also seen in Peyer's patches, and occult blood was detected in many affected segments of intestine. These results are consistent with early laboratory pulsed-ultrasound results.
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