Abdominal aortic aneurysm (AAA) causes over 10,000 deaths annually in the US. The majority of AAA are silent and asymptomatic until rupture. If detected early, surgical interventions have been proven effective with in-hospital mortalities < 4% compared to mortality higher than 40% in already ruptured AAAs. Ultrasound- based maximum diameter measurements of AAA is currently the primary determinant of its rupture risk with 5.5 cm often used as the decision criteria. However, it has been reported that up to 23% of AAAs ruptured at a diameter less than 5 cm and up to 60% of AAAs with a diameter greater than 5 cm never experienced rupture Thus, more reliable predictors of rupture risk are urgently needed. In particular, a molecular imaging positive finding may assist with risk stratification in cases where anatomic-based findings are ambiguous (e.g. aortic diameter in range 4.5 - 6.5 cm). Molecular imaging is a promising approach for early detection of AAA risk that contrasts with anatomical imaging in which only relatively late AAA progression is detectable. The correlation between risk of AAA rupture and biomarkers has been demonstrated. MRI, optical, and PET methods have all demonstrated pre-clinical success in detection of markers for AAA rupture but none of these modalities simultaneously meets the need for rapid, low-cost, radiation-free, molecular marker detection necessary to achieve widespread clinical adoption. Ultrasound-based molecular imaging is an ideal modality because it meets the above needs and existing instrumentation, already in use for making diameter measurements during existing AAA screening protocols, requires only very minor adaptation. Unfortunately, existing ultrasound- based molecular imaging is unable to measure molecular marker concentration in large blood vessel environments, and thus AAA risk assessment using ultrasound has not yet been attempted. The present investigators have recently invented a new ultrasound-based molecular imaging strategy that overcomes the limitations of previous techniques in large blood vessel environments. This method, referred to as ?modulated Acoustic Radiation Force? (mARF)-based imaging, is the first ultrasound technology to demonstrate quantitative measurements of molecular marker con-centration (in units of sites/?m2) in large blood vessels. Earlier and more accurate prediction of future AAA rupture risk will improve mortality rates and reduce healthcare costs associated with AAA.

Public Health Relevance

Abdominal aortic aneurysm (AAA) causes over 10,000 deaths annually in the US but is very rarely detected prior to aneurysm rupture. We propose to develop a molecular targeted, ultrasound, imaging method that is minimally invasive, fast, safe and inexpensive that will provide a more reliable prediction of AAA risk. We perform a sequence system development, methodical laboratory testing and studies in a small animal to validate the potential of the method for future translation to clinical use.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL132395-02
Application #
9319303
Study Section
Biomedical Imaging Technology Study Section (BMIT)
Program Officer
Danthi, Narasimhan
Project Start
2016-07-21
Project End
2020-04-30
Budget Start
2017-05-01
Budget End
2018-04-30
Support Year
2
Fiscal Year
2017
Total Cost
Indirect Cost
Name
University of Virginia
Department
Biomedical Engineering
Type
Biomed Engr/Col Engr/Engr Sta
DUNS #
065391526
City
Charlottesville
State
VA
Country
United States
Zip Code
22904
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Herbst, Elizabeth B; Unnikrishnan, Sunil; Wang, Shiying et al. (2017) The Use of Acoustic Radiation Force Decorrelation-Weighted Pulse Inversion for Enhanced Ultrasound Contrast Imaging. Invest Radiol 52:95-102
Wang, Shiying; Unnikrishnan, Sunil; Herbst, Elizabeth B et al. (2017) Ultrasound Molecular Imaging of Inflammation in Mouse Abdominal Aorta. Invest Radiol 52:499-506