How long does a cardiac CT acquisition take?
To acquire an image, the gantry of the CT scanner must rotate 180 degrees around the patient. With a rotation speed of 330 msec, a modern scanner acquires enough data to make an image in 165 msec, which is the temporal resolution. Some scanners have two x-ray tubes, which permit image acquisition using only 90 degrees of gantry rotation, improving the temporal resolution to 83 msec. This temporal resolution, however, is still quite slow compared to digital subtraction angiography (DSA), which has a temporal resolution of 7 to 10 msec, and therefore gating is still required. The total acquisition time will depend on the width of the CT scanner detector; wide detector (e.g., 320 slice) machines can acquire images of the entire heart during a single heartbeat, while smaller (e.g., 64 slice) detector scanners will take 4 to 5 heartbeats.