Fast acquisition of myocardial perfusion and LV contractile indices with multi-pinhole SPECT

Objectives Fast acquisition of cardiac perfusion data leads to improved efficiency by faster throughput. Provided the measurement of LV contractile indices is of sufficient quality, fast acquisition can also improve interpretation by providing additional information. Acquiring 2-4 minute images serially during recovery from stress provides an opportunity to measure LV contractile indices during the recovery phase while preserving perfusion data.

Methods An 18 pinhole collimator was used on a dual headed Vertex camera. An advantage of Multi-Pinhole SPECT (MP-SPECT) is that the whole heart is continuously imaged at a high count rate allowing fast acquisition of image data. Accurate myocardial blood flow distribution and left ventricular EF, segmental motion and segmental thickening can be acquired in as little as 2 minutes. Patients were injected at rest with 330 MBq of Tc-99m. At peak stress, patients were injected with either 740-925 MBq Tc-99m (Tc/Tc protocol), or with 150 MBq Tl-201 (simultaneous Tc/Tl protocol). Immediately post stress, patients were imaged during recovery for 16-20 minutes using listmode acquisition. The listmode data sets were broken down into 2-4 minute increments offline and each 2-4 minute increment was reconstructed into 16 frame per cardiac cycle gated studies. The 2-4 minute images were diagnostically adequate.

Results Variations in LV contractions were observed representing: 1) stepwise decrease in LVEF with normal segmental function in normals and patients with blood flow difference in the absence of ischemia, 2) initial abnormal segmental function with recovery of function in patients with myocardial ischemia and 3) segmental chnages in viable or non-viable infarction.

Conclusions Multi-Pinhole SPECT allows fast acquisition of both myocardial perfusion and LV contraction data.