Current Status of Patient Radiation Exposure of Cardiac Positron Emission Tomography and Single-Photon Emission Computed Tomographic Myocardial Perfusion Imaging.

BACKGROUND: Radiation exposure during nuclear cardiology procedures has received much attention and has prompted citations for radiation reduction. In 2010, the American Society of Nuclear Cardiology recommended reducing the average patient study radiation exposure to <9 mSv in 50% of studies by 2014. Cardiac positron emission tomography (PET) for myocardial perfusion imaging (MPI) has emerged within recent years, but current radiation exposure in cardiac nuclear PET laboratories is unknown. This study evaluated current reported patient radiation exposure from nuclear laboratories in the United States applying for Intersocietal Accreditation Commission accreditation for MPI using single photon emission computed tomography (SPECT) or PET. METHODS AND RESULTS: This was an analysis of nuclear cardiology studies submitted to the Intersocietal Accreditation Commission for either or both cardiac PET and SPECT accreditation. Cardiac SPECT data represented year 2015 while PET data combined years 2013 to 2015. Data was analyzed with χ2 and Mann-Whitney U tests (reported as median, 25th percentile, and 75th percentile). Reported PET MPI radiation exposure for 111 laboratories (532 patient cases) was 3.7 (3.2-4.1) mSv per study with no geographic variation. Reported SPECT MPI radiation exposure for 665 laboratories (3067 patient studies) was 12.8 (12.2-14.3) mSv. Highest radiation exposure was found in the South region. Technetium-only studies resulted in a median of 12.2 mSv per study. CONCLUSIONS: Radiation exposure from cardiac PET MPI in US laboratories applying for Intersocietal Accreditation Commission accreditation is low (111 laboratories, 3.7 mSv) and substantially lower than cardiac SPECT (665 laboratories, 12.8 mSv).

Stress Induced Cardiomyopathy with Midventricular Ballooning: A Rare Variant.

Stress cardiomyopathy (SCM) also referred to as the "broken heart syndrome" is a condition in which intense emotional or physical stress can cause fulminant and reversible cardiac muscle weakness. SCM most commonly involves the apical segment of left ventricle but newer and rare variants have recently been seen reported. We here report a case of rare midventricular variant of stress related cardiomyopathy. A 72-year-old female with past medical history, only significant for SVT, presented with an episode of severe substernal chest pain while hiking with her husband. She felt a significant heaviness in her chest and was short of breath. During her hospitalization she was found to have positive cardiac enzymes. EKG showed 1 mm downsloping ST segment changes. Ventriculogram during left heart catheterization revealed dyskinetic midventricle. Patient was diagnosed with midventricular SCM. The patient was placed on ACE inhibitor and beta-blocker and discharged in a well-compensated state. We suggest identifying these patients by standard lab testing, electrocardiography, echocardiography, and left heart coronary angiography and ventriculography. Management of this unique entity is similar to the other variants with close observation and treatment of accompanying heart failure, valvular dysfunction, and any arrhythmias that may develop.