Services
The UF Cardiovascular Imaging Core Laboratories can analyze images from any of the below medical procedures, both qualitatively and quantitatively. UFCICL has fully automatic databases for tracking and analyzing data.
Cardiac Magnetic Resonance Imaging
Cardiac magnetic resonance imaging uses extremely strong magnet and radio waves to produce pictures of the heart. The magnet produces a magnetic field, which causes a small amount of hydrogen atoms in the area of the heart to align. Next, concentrated pulses of radio waves are applied to the area containing the aligned atoms. As the radio waves bounce back, a unique signal is collected and used to generate a picture of the heart. The MR pictures are electrocardiogram gated to acquire images in different phases of cardiac cycle. MRI not only depicts accurate anatomy but with the help of specialized pulse sequences information about the function, perfusion or blood supply and wall thickening can be obtained.
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The UF Cardiovascular Imaging Core Lab has the largest experience in the nation in similar studies, including the first in man experience in the U.S. with intramyocardial injection of endothelial progenitor cells - a joint collaboration with the Texas Heart Institute.
- MRI Guidelines (PDF)
- Cardiovascular MR/CT Scholar Observership (UF Department of Radiology)
Cardiac Multi-Slice Computer Tomography (CT)
Currently, the gold standard to rule out coronary artery disease is conventional coronary angiography. Significant advances in technology (e.g. slip-ring technology) throughout the years enable physicians to take a closer and detailed look at smaller anatomic structures using CT technology, which uses a multilevel process, involving many steps of data acquisition, image reconstruction, display and storage.
CT scanners work by rotating a tube around a patient's body, while using X-ray radiation to capture images. Fixed detectors (forth generation scanner) or a moving ring of detectors (third generation scanner) captures the remaining radiation after it has passed through the patient's body. These detectors are able to measure the energy from impinging X-rays due to scintillation and then convert this light-output into electrical (analog) signals, which are then converted into digital data. These data are sent to a computer where the post-processing workflow (image reconstruction process for display, manipulation and storage) is initiated.
Due to enormous technical developments, today's cardiac multi-slice computer tomography (MSCT) scanners are able to create up to 64 axial slices per rotation. Using ECG gating, it is possible to reconstruct a beating heart in every cardiac phase. This leads to a significant reduction in scan time and improved temporal and spatial resolution. Coronary vessels can now be displayed in a detailed manner allowing the detection of atherosclerotic changes in the vessel wall and detecting of higher grade stenosis. A 64-slice CT scanner covers the whole heart volume in only one breath hold of the patient (acquisition time depending on the study: approximately 10 seconds) is now available at the Cardiovascular Center at Shands Jacksonville.
Two different diagnostic approaches in cardiac CT have to be considered:
- Coronary calcium screening (scoring) For this purpose a non-contrast scan is used. Coronary calcifications are denser than the surrounding tissue and appear as bright white. Therefore an automatic software tool is able to identify these lesions using a certain threshold of 130 Hounsfield Units (HU). The investigator then marks all the calcification relating to coronary arteries. A defined coronary calcium score (Agatston Score, volumetric score and calcium mass score) can now be calculated. It is well established that coronary calcium is an independent risk factor for coronary artery disease. If no calcium is found (Score 0) it is very unlikely to show higher grade stenoses of coronary vessels. On the contrary, calcium within coronary vessels only appears in conjunction with atherosclerosis and allows us to assess individual's risk profile.
- Non-invasive coronary angiography (MSCTA) After administration of a non-ionic contrast agent, the entire coronary vessel tree can be visualized. With this technology, physicians are able to detect significant luminal obstructions due to atherosclerotic changes of the intimal vessel layer. Even non-calcified plaques can now be depicted and many studies have showed high negative predictive value in ruling out significant coronary artery disease. Histopathological studies have shown that rupture-prone plaques show some characteristic features like a thin fibrous cap infiltrated by macrophages and high lipid content (necrotic core). The ability of MSCTA to identify these high risk plaques is currently under investigation. Also, current investigations at our institution include characterization of plaque morphology by MSCTA and comparison with other diagnostic imaging modalities like intravascular ultrasound (IVUS). Beside plaque imaging and stenosis detection this modality offers the possibility to diagnose coronary anomalies, myocardial bridging, intracardial thrombus or myocardial infarction.
Coronary Angiography
Coronary angiography produces pictures of blood vessels of the heart, called coronary arteries. A catheter carrying a dye-like material, which can be seen with special X-ray equipment, is inserted into one of the patient's arteries. Once the catheter reaches the heart it releases the dye while pictures are simultaneously acquired to show the dye's flow or lack of flow through the coronary arteries.
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In the core lab, quantitative coronary angiography computes these results into actual numbers to calculate volume and area of the vessel. This facilitates the subjective independent assessment of vessel constriction and atherosclerotic plaque, which is a soft plaque with lots of lipids, a hard calcified plaque or a mixture of plaque.
- Angiography Guidelines (PDF)
- TIMI Guidelines (PDF)
- Myocardial Perfusion Analysis (PDF)
Intravascular Ultrasound (IVUS)
Intravascular ultrasound uses high-pitched sound waves, inaudible to humans, to create a map of a patient's arteries. A tiny ultrasound device enters the body on the tip of a catheter. Once the catheter reaches its intended destination the ultrasound device will send and receive high-pitched sound waves while rotating in order to achieve a full view of the area. This data is then used to create a detailed map of the artery, including the amount, type and thickness of plaque buildup.
Our lab use these images to make a 3-D reconstruction of the vessel to allow visualization of the vessel from the inside. With this technique, not only the exact size but also the nature of the atherosclerotic plaque, which is a soft plaque with lots of lipids, a hard calcified plaque or a mixture of plaque is assessed. The plaque rupture is the most common complication associated with atherosclerosis, accounting for approximately 70 percent of all fatal acute myocardial infarctions. IVUS is a validated and clinically available tool for assessment of such plaques, vessel dimensions and stent restenosis.
- IVUS Guidelines (PDF)
- Volumetric IVUS Analysis (PDF)
Peripheral Angiography
Imaging of peripheral vascular disease (PVD), 
which refers to diseases of the blood vessels located outside the heart and brain, can be performed by angiography, where a catheter is used to inject radiodense contrast agent while an X-ray is taken. Modern magnetic resource arteriogram (MRA) scanners provide direct imaging of the arterial system as an alternative to angiography. MRA provides complete evaluation of the aorta and lower limb, carotid and renal arteries without the need for an angiogram's arterial injection of contrast agent.
Our lab uses quantitative vascular analysis (QVA) and quantitative MRA assessment to analyze these images and to accurately calculate volume and area of the vessel in the patients with PVD. These analyses are validated and clinically available tools for assessment of atherosclerotic plaques, vessel dimensions and in-stent restenosis.
Wall Shear Stress Assessment
This study applies in vivo technique for profiling hemodynamics and wall shear stress distribution in human coronary arteries. The methodology involves fusion of intravascular ultrasound and biplane angiograms to reproduce the 3-D arterial geometry. This geometry is then used in a Computational Fluid Dynamics module for flow modeling. The Walburn and Schneck constitutive relation is used to represent the non-Newtonian blood rheology. The methodology is then applied to study the relationship between wall shear stress and location of Neointimal Hyperplasia following stent implantation. Low wall shear stress predicts the location of Neointimal Hyperplasia when bare metal stents are deployed. Currently under investigation at the UF Cardiovascular Core Lab, in collaboration with the University of Central Florida, is if wall shear stress plays the same pathophysiologic role following implantation of drug eluting stents.