What is this Image? 2020: Image 2 Result
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Rush University Medical Center, Chicago, IL Division of Cardiology, Rush University Medical Center, Chicago, IL
doi:10.1007/s12350-020-02324-9
INTRODUCTION Extracardiac radioisotope uptake on myocardial perfusion imaging can indicate or mimic non-cardiac pathology. We present a positron emission tomography (PET)-computed tomography (CT) fusion image with extracardiac thoracic uptake in a pattern that imitates a second heart in the chest. CLINICAL HISTORY A 77-year-old woman with history of coronary artery disease, chronic obstructive pulmonary disease and gastroesophageal reflux disease was referred for stress testing in advance of starting in a pulmonary rehabilitation program. Her baseline electrocardiogram showed a left bundle branch block and she therefore underwent myocardial perfusion imaging with vasodilator stress. DISCUSSION Dynamic rest and stress images with CT attenuation correction were obtained after the injection of 13.3 mCi of the radioisotope Rubidium-82. PET-CT fusion images showed significant extracardiac radioisotope uptake in the posterior thorax in a pattern simulating two hearts (Figure 1). This extracardiac activity was suspected to be due gastrointestinal uptake. Review of CT images alone confirmed a large left sided diaphragmatic hernia with gastrointestinal contents, perhaps colon, in the
Reprint requests: Kim A. Williams Sr., MD, MACC, FAHA, MASNC, FESC, Division of Cardiology, Rush University Medical Center, 1717 W. Congress Parkway, Suite 303 Kellogg, Chicago, IL 60612; [email protected] J Nucl Cardiol 1071-3581/$34.00 Copyright Ó 2020 American Society of Nuclear Cardiology.
thoracic cavity (Figure 2). Coronal CT images from several years prior show this defect, with the majority of the stomach in the thorax (Figure 3). TEACHING POINTS – CT and myocardial perfusion imaging (MPI) fusion, or co-registration, is one of multiple quality control techniques that help mitigate potential artifacts. CT and myocardial perfusion images, which are obtained sequentially, are fused together. If the images are registered correctly, radioisotope uptake should correspond to the heart on CT. Sometimes, however, review of fusion images may show misregistration or significant extracardiac uptake. Misregsitration influences radioisotope distribution and can lead to errors in interpretation.1 – Extracardiac radioisotope uptake is common, and careful assessment may identify non-cardiac pathologies. The incidence of non-cardiac scintigraphic findings may be as high as 2.8%.2 Reasons for extracardiac radioisotope uptake range from physiologic gastric and intestinal uptake to benign pathologies such as cholecystitis and renal cysts to malignant lesions.3 – Both the stomach and intestines have been shown to have high Rubidium-82 activity.4 In cases of diaphragmatic hernia, gastrointestinal uptake can appear as abnormal thoracic activity. This can lead to inferior cardiac wall artifact or mimic pathology such as lung cancer;5 or in the current case, simulate a second heart.
FEATURE RESULTS There were 5
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