The 3 Worst Reasons For the Recent Growth in Imaging Use Defensive medicineDefensive medicine Self-referralSelf-referral Inappropriate indicationsInappropriate indications
What is An Appropriate Imaging Study? An appropriate imaging study is one in which the expected incremental information, combined with clinical judgment, exceeds the expected negative consequences* by a sufficiently wide margin for a specific indication that the procedure is generally considered acceptable care and a reasonable approach for the indication. *Negative consequences include the risks of the procedure (i.e., radiation or contrast exposure) and the downstream impact of poor test performance such as delay in diagnosis (false negatives) or inappropriate diagnosis (false positives).
Modern Cardiac Imaging Facts Extremely powerful in revealing non-invasive information –Anatomy, patho-physiology –Therapeutic relevance to treatment Highly inter-disciplinary –Many stakeholders Very costly –Capital investment –Running costs –Sophisticated manpower –Complex interaction between “players”
Technologies That Will Be Discussed CXR (briefly) Nuclear Studies Echocardiography Computerized Tomography Magnetic Resonance Imaging/Angiography
CXR Chest Pain— –rule out dissection –pneumothorax –hemothorax –pneumonia –chamber dimensions –effusions –pulmonary vascularity –coronary aneurysm Cough/Dyspnea/Fever with sxs Cancer screening “forget it” Ordering and not following up “missed mass”
Role of Nuclear Cardiac Imaging Diagnosis of coronary artery disease,coronary artery disease Evaluation of cardiac function abnormalities, Monitoring of patients under treatment for established cardiac disease. Verification of the diagnosis of acute myocardial infarctionacute myocardial infarction
Up to 20% of nuclear stress tests are false positives!******* Maybe we should re-name it “unclear” medicine –Most cardiologists do!! Inferior wall defects are especially common due to the overlap of the diaphragm with the heart muscle, yielding the appearance of reduced blood flow. Anterior defects are common in females with large breasts for the same reasons……..as well as many men! *******These numbers are under study environments in peer reviewed interpretations
Quality control 1. Motion -- There is no evidence of patient motion. 2. Alignment --The alignment is very good. 3. Count Increase --The myocardial max counts increases in the stress study as expected. 4. Normalization --Both studies are normalized to the portion within the myocardium with the highest uptake. 5. Extra-Cardiac Activity --There is no significant extra cardiac activity. 6. Soft tissue attenuation– minimized 7. Protocol consistency
ECG Gated SPECT imaging (MUGA: multi gated acquisition) Simultaneous assessment of perfusion and function in a single injection, single acquisition sequence. Tc-99m permits evaluation of regional myocardial wall motion and wall thickening throughout the cardiac cycle Quantitates LV volume and EF
Indications for Pharmacologic Nuclear Perfusion Stress Imaging Inability to perform adequate exercise Left bundle branch block Ventricular pacemaker CCB’s or Beta blockers Evaluation of patients very early after acute MI (<3 days) or very early after stenting (<2 weeks)
Nuclear Imaging Out comes data is good. Large area of ischemia, multiple ischemic locations, poor LV function, Lung uptake - bad prognosis Established for peri-operative ?? need Too sensitive for non-life threatening CAD High radiation exposure $$$$$$
Calcium Scoring If you know you are at high risk – How will a scan change outcomes?
Heart Scan CT calcium score If you want to do more angiograms promote CT Ca Score No outcome data but may add a little to Framingham Treat risk factors regardless of Ca Insurance will pay in Texas Radiation is likely greater risk than benefit—radiation is lower than CTA or nuke, however
CT Angiography Less invasive than cath—technology has outpaced our knowledge as to how to use it Radiation is high Renal failure and contrast nephropathy similar to Coronary Angiography If need intervention radiation and contrast is doubled $$$$$$$$$
Magnetic resonance imaging Public Health Advisory: Risk of Burns during MRI Scans from Transdermal Drug Patches with Metallic Backings Pacemakers, Defibrillators Tattoos (myth busters) Gadolinium nephrogenic systemic fibrosis (NSF) in renal insufficiency
Should I worry about radiation associated with medical testing?
Echo Echo is safe – no radiation Information can change therapy Good correlate to physical exam Outcome data is good - sudden death, CAD prognosis, Heart failure prognosis It will do more in the future It is such a good test the government will make reimbursement zero $’s and hope you use the test anyway at your cost.
Types of Echo Transthoracic Transesophageal Stress- exercise and Dobutamine 2- and 3- D
Echo assessment Allows the assessment of: Left ventricular size and function, including regional wall motion abnormalities Right ventricular size and function Atrial abnormalities The heart valves – Mitral, Aortic, Tricuspid and Pulmonary (stenosis, regurgitation etc) Intracardiac pressures Lung pressures http://www.asecho.org
Stress Echo Similar appropriateness to RNI No radiation risk Less sensitive but more specific Technical limitation (patient, site, interpreters) $$ cheaper and getting cheaper Review on inappropriate use
CLASSIFICATION OF APPROPRIATENESS IN A LARGE ACADEMIC CARDIOLOGY PRACTICE SPECT ECHO Gibbons et al, 2008 JACC 51: 1283-9 n=284 n=298
Inappropriate Imaging Indications Stress Echo and Nuclear Asymptomatic, low risk 48%Asymptomatic, low risk 48% Pre-op, intermediate risk surgery able to exercise 17%Pre-op, intermediate risk surgery able to exercise 17% Symptomatic, low pre-test probability, able to exercise 13%Symptomatic, low pre-test probability, able to exercise 13% Pre-op, low risk surgery 10%Pre-op, low risk surgery 10% Mayo Clinic, Gibbons et al, 2008 JACC 51:1283-89.
Conclusion Radiation is a serious threat We’re likely ordering too many imaging studies –U–Use the appropriateness criteria from the ACC/AHA Never order a test unless you have a plan for the results
A CHEERFUL HEART IS GOOD MEDICINE– PROVERBS 17:22
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