PESA Project- Progression of early subclinical atherosclerosis

MICINN, ISCIII, CNIC, Fundación PROCNIC, Santander MICINN ISCIII CNIC Fundación PROCNIC Santander Proyecto PESA - Progression of early subclinical atherosclerosis

FUNDACION CNIC CARLOS III

Melchor Fernández Almagro, 3
Postal Code: 28029, Madrid, Spain
Phone: (+34) 91 4531200
Fax: (+34) 91 4531245

Imaging tests

Carotid Ultrasound Imaging

Carotid ultrasound imaging, also known as carotid doppler, is a non-invasive diagnostic imaging procedure that does not cause discomfort. High frequency ultrasound waves are used to image the artery and monitor the circulation. The echoes reflected from the anatomical structures are computer processed to generate images of the carotid arteries, the large vessels in the neck that supply blood to the brain. In PESA, the technique is used to detect atherosclerotic plaques that reduce the vessel diameter and impede blood flow, a finding that would indicate a high risk of a cerebrovascular accident.

Unlike angiography, carotid ultrasound imaging does not use X rays, and thus does not expose subjects to ionizing radiation and does not require preparation of the patient.

In PESA CNIC-Santander study uses the latest generation ultrasound equipment, which allows three-dimensional (3D) imaging in real time. 2D ultrasound systems have known limitations in terms of predictive value for cardiovascular risk assessment in humans.

The data acquired is being managed with a pioneering advanced software application that allows quantification of the 3D images and evaluation of atherosclerotic plaques and their progression in the same individual over several years.

Three-dimensional carotid ultrasound is so new that, at present, it is not available for clinical use.

Abdominal Ultrasound Imaging

This non-invasive technique uses ultrasound to produce images of the abdomen heart, providing information about the characteristics of the abdominal aorta. The technique can detect abnormal dilation of the aortic wall, a phenomenon known as aneurysm, and the presence of atherosclerotic plaques.

Ilio-femoral Ultrasound Imaging

This non-invasive technique uses ultrasound to produce images of the ilio-femoral region. These images are used to detect the presence of alterations in the iliac arteries (lower abdomen) and femoral artery (in the inner thigh) using the same principles as used in carotid ultrasound.

Computed Axial Tomography (CAT)

This diagnostic procedure combines the use of X rays with rotating electronic detectors. The sequences of radiographic images obtained are computer processed to yield a series of progressive transverse sections that build up a three-dimensional picture of the region being studied. The transverse, multidimensional images are displayed on a monitor.

The latest CAT scanners are so fast they can scan large sections of the body in a few seconds.

Cardiac CAT scans provide information about the presence, location and extent of atheroma plaques (or calcified plaque) in the coronary arteries, the blood vessels that supply oxygenated blood to the heart muscle. The presence of such a plaque (generated from deposits of cholesterol and other substances beneath the inner lining of the artery) is a sign of atherosclerosis and of a heightened risk of suffering a cardiovascular event. The results of a cardiac CAT scan are expressed as a calcium score, and this test is also known as coronary artery calcium scoring.

CAT scans are painless and do not require injection of contrast material. Subjects just need to stay still and breathe shallowly for a short time so that images can be captured with precision.

Magnetic Resonance Imaging (MRI)

This is another non-invasive technique that provides detailed images. In PESA, images are captured in the carotid and ilio-femoral regions.

Unlike radiographic techniques such as CAT, which uses X rays, MRI produces images through the combined use of powerful magnets and ultrasound waves. The magnetic field of the MRI machine excites hydrogen atoms in the body, which produce small radio signals. These signals are captured and processed into images displayed on a monitor.

MRI is frequently used together with other imaging techniques, such as PET or CAT, to achieve a more precise definition.

Depending on the area to be studied, the patient might be asked not to eat for four to six hours before the scan. In general, no other preparation is necessary.

Positron Emission Tomography (PET)

This non-invasive imaging technique uses small amounts of a radioactive substance called a radiotracer. The scanner is linked to a computer program that measures the amount of radiotracer absorbed by the area being studied. The images obtained give detailed information about the structure, function and metabolism of tissues and organs.

Today PET is often used in combination with CAT or MRI, since these combinations provide information about anatomy and function and allow more precise diagnosis than the use of the techniques applied separately.

In the PESA CNIC-Santander study, a PET scan is performed using labeled glucose (18FDG) as a radiotracer. Glucose is the main nutrient of cellular metabolism and is selected as a radiotracer because it strongly lights up areas of higher metabolic activity in the arterial territories being explored. Areas of high metabolic activity in the arterial walls correlate with the existence of inflammation accompanying atherosclerotic disease. The information obtained from the 18FDG PET completes the study of atherosclerosis by giving a functional or metabolic view of the disease.

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