Position of Subcutaneous Implantable Cardioverter-Defibrillators and Possible Interference on Myocardial Perfusion Imaging.

Implanted cardioverter-defibrillators can prevent sudden cardiac death in at-risk patients. In comparison with conventional transvenous systems, entirely subcutaneous implantable cardioverter-defibrillators have produced similar reductions in the rate of sudden cardiac death but with fewer sequelae. An infrequently reported drawback of subcutaneous devices, however, is the potential for generating attenuation artifact during nuclear myocardial perfusion imaging. We had concerns about potential attenuation artifact in a 65-year-old man with coronary artery disease but found that having positioned the pulse generator in the midaxillary zone avoided problems.

The Significance of ST Depression in a Postmenopausal Woman on Estrogen Therapy during Regadenoson Myocardial SPECT Imaging.

The incidence of false-positive stress tests has been noted in women, especially on hormone replacement therapy. Current literature describes this phenomenon in treadmill and adenosine stress tests. The introduction of regadenoson as a vasodilator agent has been widely adopted owing to its potency and specificity. To our knowledge, false-positive stress test with regadenoson in a postmenopausal woman on estrogen has never been described. Given the higher chronotropic response with regadenoson, we believe that normal perfusion images with a higher heart rate response indicate a good prognosis in such patients.

Identification of incidental hepatic malignancy as photopenic defect on 99mTc-sestamibi myocardial perfusion imaging.

A 63-year-old male patient undergoing cardiac SPECT examination was incidentally found to have a large, photopenic (tracer-deficient) region in the right lobe of the liver. Follow-up abdominal CT scan demonstrated a corresponding large (7.8 cm × 6.9 cm), hypodense hepatic lesion. Subsequent CT-guided biopsy revealed metastatic carcinoma of uncertain primary source.