Myocardial perfusion scintigraphy in a case of dextrocardia: Doing it “right”
A 54-year-old type 2 diabetic and hypertensive female patient with dextrocardia and situs inversus was referred for evaluation of coronary artery disease. The patient underwent treadmill test with Bruce protocol. The electrocardiogram with the leads placed conventionally [] shows P inversion in the lead 1 inverted QRS complexes in lead 1 with right axis deviation and equivocal and non-progressive R waves in the precordial leads. Reversal of the leads shows upright P and QRS in lead 1 with normal QRS progression in chest leads []. Chest X-ray also showed cardiac shadow on the right side []. At the peak stress, Tc99m-tetrofosmin (370MBq) was injected. Following the stress, tomographic imaging was carried out under a dual head gamma camera (Infinia hawkeye-4, General Electricals, Milwaukee, USA) with a low dose computed tomography (140 mV, 2 mA) for attenuation correction. Images were acquired in L mode over 180° starting from right posterior oblique to left anterior oblique projections instead of the standard right anterior oblique to left posterior oblique views. Rest images were acquired on the same day after reinjection of tracer. The images show findings of situs inversus and dextrocardia []. Reversible perfusion defect was also noticed in the free wall (antero-lateral segment as per conventional nomenclature). Attenuation correction in this case shows the severity and extent of defect to be less as compared to uncorrected images suggesting an attenuation artefact [].