Post on 18-Jul-2020
CARDIAC IMAGING
Cardiac disease is the leading cause of death and disability in the United States. The SEMC radiology department is dedicated to partnering with you to ensure comprehensive imaging
workup of cardiac diseases.
CARDIAC CT The radiology department at SEMC has a 256 slice CT scanner in the Emergency Department which has allowed us to expand our program of cardiovascular CT. The scanner is equipped with iterative reconstruction algorithms and dose modulation to minimize radiation dose and maximize image quality. This is particularly important in the area of cardiac CT, where doses tend to be higher due to the need for EKG gating.
Calcium Score
INDICATIONS:
1. In conjunction with coronary artery CTA, to assess the amount of coronary artery calcification in order to appropriately plan the coronary artery CTA.
2. As a standalone test, calcium scoring can be useful in assessing the risk of obstructive coronary artery disease. Clinical trials show that coronary artery calcification on CT is highly sensitive and moderately specific for the presence of moderate or greater degrees of coronary atherosclerosis and outperforms the Framingham risk score.
Calcium scoring is done with EKG gating, but without IV contrast. The coronary arteries are analyzed by the technologist and radiologist, according to the Agatston protocol. They are reported as absolute number, but also as a percentile compared to age and gender matched controls.
Coronary Artery CTA
INDICATIONS:
1. Evaluate patients at low to moderate risk of coronary artery disease in the absence of cardiac enzyme elevation and ischemic ST changes (ACR appropriateness level 6).
2. Evaluate patients with indeterminate myocardial perfusion scans due to breast attenuation.
3. Noninvasively exclude the possibility of coronary artery disease in patients requiring valve replacement or repair, many of whom are young and at low risk of having obstructive coronary artery disease.
4. Comprehensively evaluate congenital anomalies of coronary artery origin and course using 3D imaging.
EKG GATING/HEART RATE Cardiac CTA is performed with EKG gating. Typically cardiac CT examinations require a heart rate under 65. This is particularly important for younger patients as it allows the greatest amount of radiation dose reduction. It is important in older patients as well, since their vessels tend to be calcified and therefore easier to evaluate at lower heart rates. Both prospective and retrospective forms of EKG gated cardiac CT exams are available. This allows us to tailor the examination according to patient age, body habitus, and heart rate. Heart rate reduction is best achieved by administering oral metoprolol for 24 hours in advance of the examination. In some cases, IV metoprolol is added or substituted for oral administration. IV CONTRAST CT angiography requires IV contrast administration, so renal function tests performed within 30 days prior to imaging are necessary for all patients over age 60 or with risk factors that might predispose
SEMC RADIOLOGY UPDATE 9/15/2014 Edition 3, Volume 1
them to abnormal renal function. If necessary, patients with mildly to moderately reduced eGFR can be hydrated in the radiology department prior to imaging, to allow them to more safely receive IV contrast material.
Planning of the imaging is performed at the scanner console by an experienced CT technologist and radiologist team. Acquiring the images takes less than one minute. Once the images are acquired, the radiologists and technologists work collaboratively to generate 2D and 3D reconstructions that accurate evaluate and display the relevant anatomy. Representative images are saved to PACS. Cardiac CT is available during regular business hours, Monday thru Friday. It can be ordered through central scheduling. Dr. Rebecca Schwartz and Dr. Ashley Davidoff are available for consultation regarding any patient prior to or following any cardiac CT. INSURANCE COVERAGE Insurance coverage for coronary artery CTA has been challenging. Medicare provides coverage for most typical indications (atherosclerotic disease, valvular heart disease, congenital anomalies) but commercial insurers evaluate patients on a case by case basis and many do not cover this procedure. However, a patient who wishes to pay out of pocket may do so at a total cost of $399 for calcium score CT and $879 for coronary artery CTA with calcium score. CARDIAC MRI St. Elizabeth’s has the only cardiac MRI program at Steward. There are two 1.5 T MRI units at SEMC, both of which have recently been upgraded with a new software package to enable state of the art cardiac MRI. The upgrade allows us to image much more quickly and reliably, with fewer artifacts. We routinely scan patients from across the Steward system. Indications:
1. Evaluation of nonischemic cardiomyopathies 2. Viability after myocardial infarction 3. Ejection fraction verification 4. Evaluation for arrhythmogenic right
ventricular cardiomyopathy (ARVC, also known as ARVD) in patients with arrhythmias or family history
5. Evaluation of coronary artery origins (this can be done by CTA as well, but in MRI can be done without IV contrast, making it possible to do it in patients with renal compromise and/or CT contrast allergy)
6. Myocarditis/pericarditis
Figure 1: Top image demonstrates normal, high quality coronary artery CTA “globe view”; Bottom image demonstrates short axis and filet views of cakcified, diseased LAD coronary artery
7. Cardiac or pericardial tumor evaluation 8. Differentiating cardiac thrombus from masses
of different types, and characterizing those masses
9. Evaluation of infiltrative cardiomyopathies, e.g., amyloidosis or hemochromatosis
IV CONTRAST Most types of cardiac MRI require gadolinium contrast administration. In any patient over age 60 or with history of renal disease or at elevated risk of renal disease, renal function studies obtained within the past 30 days must be available. As long as the eGFR is greater than 30 and the patient does not have either acute kidney injury or severe intercurrent acute illness (ICU stay, recent surgery), or other contraindication to gadolinium (e.g. allergy), gadolinium will be administered. In most cases, if gadolinium cannot be administered, cardiac MRI should not be ordered, but there are a few exceptions and we are happy to speak with you about any individual case. EXAM TOLERANCE Patients should be made aware that the examination is lengthy, often more than one hour. If they are likely to be claustrophobic or have severe anxiety about MRI, it is recommended that the ordering provider prescribe the patient an anxiolytic for him/her to take upon arrival to the MRI department. CONTRAINDICATIONS Contraindications to cardiac MRI include typical MRI contraindications (most pacemakers, intraorbital metallic foreign body, certain kinds of
intracranial aneurysm clips and certain prosthetic cardiac valves). Patients with many metallic foreign bodies such as orthopedic hardware and most vascular stents are candidates for MRI, including cardiac MRI. Patients who cannot lie flat cannot have cardiac MRI. The patient should also be able to suspend respiration for up to 15-‐20 seconds. If this is a concern before the exam, preMRI dieresis or thoracentesis should be
considered. The upper weight limit for our MRI machines is 300 lbs, but some patients weighing between 250-‐300 lbs with wide shoulders may be too physically large to allow the magnet to function properly. Imaging includes structural images; cine FIESTA movie type images to evaluate cardiac wall motion, ejection fraction, and valve function; and late gadolinium enhanced images, to evaluate for scar and/or enhancement of cardiac masses. After the study is complete, images are transferred to a dedicated cardiac MRI workstation, where they are analyzed and manipulated collaboratively by the radiologist and technologist. Cardiac MRI is available during regular business hours, Monday thru Friday. It can be ordered through central scheduling. Dr. Rebecca Schwartz is available for consultation regarding any patient prior to or following any cardiac MRI. INSURANCE COVERAGE There is widespread insurance coverage for the above indications, but preauthorization typically must be obtained on a case by case basis.
Figure 2: Four post contrast cardiac MRI images; top left image is of an inferior wall myocardial infarct; top right image shows a restrictive cardiomyopathy (amyloid); bottom left image is normal; bottom right image is an enhancing pericarditis
QUESTIONS?
Appointments can be made through Central Scheduling. Feel free to reach out to either of us at 617-‐789-‐2740. Cardiac Radiology Imaging Team Rebecca K. Schwartz, MD Interim Chair, SEMC Radiology Ashley Davidoff, MD
Steward Health Care� 9/5/2014 11:53 AMFormatted: Font:12 pt