History: 68 y/o man with history of myocardial infarction x 2 and CABG x 2. Enlarged heart. Elevated cholesterol. No acute complaints.
Height: 6' 0”
Weight: 161 pounds (73 kg).
Tracer dose: 30.4 mCi at peak treadmill stress
Timing: Tracer was injected at peak treadmill exercise. After a 30 minute delay, SPECT images were obtained on a conventional, dual-detector, dedicated cardiac SPECT system. Approximately one hour later, images were obtained on the CardiArc® scanner. No additional tracer was administered between the two scans.
| Scan Duration | |
|---|---|
| Conventional dual-detector w LEHR collimation |
15 min
|
| CardiArc® |
4.6 min
|
Scan findings: Markedly enlarged heart with dilated left and right ventricles. Right ventricular hypertrophy. Large regions of myocardial scar.
Even though it is hypertrophied, partial-volume effect causes the right ventricular wall (red arrowheads) to be poorly visuallized by the standard “high-resolution” sytem. The higher resolution of the CardiArc® system permits more accurate visualization of thinner structures. This marked reduction in partial volume effect results in images that most accurately reflect tissue uptake, not just tissue thickness.
Conventional, dual-detector LEHR - 15 min acquisition
CardiArc® - 4.6 min acquisition
Higher resolution gives better visualization of hypertrophied RV, even in only 1/3 the acquisition time.
Conventional, dual-detector LEHR - 15 min acquisition
This patient's right atrium (blue arrowhead) is invisible with standard-type system, despite use of high-resolution collimators. It is easily seen on the CardiArc® images taken one hour later (below).
CardiArc® - 4.6 min acquisition
The right ventricle (red arrowheads) and right atrium (blue arrowhead) are clearly identifiable. The higher resolution CardiArc® images also more clearly demonstrate the true heterogeneity of left ventricular perfusion in this patient.