• End date
    Dec 31, 2023
  • participants needed
  • sponsor
    University Health Network, Toronto
Updated on 31 March 2021


Abdominal Aortic Aneurysm (AAA) screening and an aging population have increased the prevalence of AAA diagnoses. Small AAAs (<5.5cm) are monitored with ultrasound. Large AAAs may rupture and this is usually fatal. Surgery is considered at a crude size threshold of 5.5cm when the annual rupture risk reaches 5%. AAA size is the only predictor of growth and rupture available but growth is non-linear and some small AAAs rupture. Thus, only 1 in 20 patients treated at 5.5cm will have benefited from rupture prevention in the year following surgery, and others may miss out on life-saving surgery. This study will develop an imaging tool PETMRI with radiotracer Ga- DOTATATE with high clinical utility, to improve prediction of aneurysm growth and risk.


The prevalence of abdominal aortic aneurysm (AAA) in those over 65 years is 4-8% and rising. Currently, AAA size is the only metric to determine risk of growth/rupture; we are unable to image the underlying disease process. Using size alone is problematic. For small AAAs there is no consensus between surgical societies on appropriate surveillance intervals. AAA growth is non-linear and thus some small AAAs may rupture between screening intervals.

Macrophage mediated inflammation leads to weakening of the aortic wall. Our own laboratory work indicates macrophages correlate with AAA severity in mice. In humans, activated macrophages express SomatoSTatin Receptor 2 (SSTR2). For the first time ever, using a radiotracer probe specific for SSTR 2 (gallium-dotatate), we will detect activated macrophages in AAAs using Positron Emission Tomography- Magnetic Resonance Imaging (PET-MRI). Patients attending the University Health Network (UHN) Vascular clinic undergoing ultrasound surveillance of small AAAs of differing sizes will be imaged with Ga-Dotatate PET-MRI. We will correlate aneurysm size and anatomical information with in-vivo imaging of aortic macrophages detected with Ga-Dotatate, to determine the risk of aneurysm growth.

Condition Abdominal aortic aneurysm, abdominal aneurysm, abdominal aortic aneurysms
Treatment Ga-DOTATATE PETMRI scan
Clinical Study IdentifierNCT04811222
SponsorUniversity Health Network, Toronto
Last Modified on31 March 2021


Yes No Not Sure

Inclusion Criteria

Diagnosis of asymptomatic abdominal aortic aneurysm AAA >3cm in maximum diameter
Minimum 2 years prior ultrasound or CT imaging of their AAA
No prior treatment for AAA
Age >50 years
No contraindications to PET/MRI, such as claustrophobia

Exclusion Criteria

Pregnant females. All women of child-bearing potential must receive a negative urine pregnancy test prior to administration of 68Ga-DOTATATE
Allergy and/or hypersensitivity to MRI contrast agents (gadolinium) or components of 68Ga-DOTATATE drug product (as listed in IB)
Presence of pacemaker or implanted cardioverter defibrillator (ICD)
History of alcohol or substance abuse
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