Rigid-body transformation of list-mode projection data for respiratory motion correction in cardiac PET

Abstract

High-resolution cardiac PET imaging with emphasis on quantification would benefit from eliminating the problem of respiratory movement during data acquisition. Respiratory gating on the basis of list-mode data has been employed previously as one approach to reduce motion effects. However, it results in poor count statistics with degradation of image quality. This work reports on the implementation of a technique to correct for respiratory motion in the area of the heart at no extra cost for count statistics and with the potential to maintain ECG gating, based on rigid-body transformations on list-mode data event-by-event. A motion-corrected data set is obtained by assigning, after pre-correction for detector efficiency and photon attenuation, individual lines-of-response to new detector pairs with consideration of respiratory motion. Parameters of respiratory motion are obtained from a series of gated image sets by means of image registration. Respiration is recorded simultaneously with the list-mode data using an inductive respiration monitor with an elasticized belt at chest level. The accuracy of the technique was assessed with point-source data showing a good correlation between measured and true transformations. The technique was applied on phantom data with simulated respiratory motion, showing successful recovery of tracer distribution and contrast on the motion-corrected images, and on patient data with C15O and 18FDG. Quantitative assessment of preliminary C15O patient data showed improvement in the recovery coefficient at the centre of the left ventricle.

Hybrid Imaging: Instrumentation and Data Processing

“…Reprinted from Rausch et al [181] with permission from Elsevier. [193], during PET-image reconstruction-motion compensation during image reconstruction (MCIR) [194], and after PETimage reconstruction [195]-Reconstruction Transform Average (RTA). Recent studies have been performed to evaluate the performance of these three methodologies [196,197].…”

Clinical respiratory motion correction software (reconstruct, register and averaged—RRA), for 18F-FDG-PET-CT: phantom validation, practical implications and patient evaluation

“…These last approaches are subject to noise amplification or computational issues. 8,19,20 In 2009, Werner et al 21 examined 18 patients with lung cancer and identified a significant decrease in tumour volume on images gated to respiratory movement compared with nongated images (244.5%, p 5 0.025). The gated tumour volume was not different compared with the volume obtained on the CT images.…”

Simultaneous PET–MR acquisition and MR-derived motion fields for correction of non-rigid motion in PET

“…In practical terms, the situation is further complicated because motion can be irregular [9,10] and non-periodic over the duration of a PET acquisition. Researchers have shown some success in estimating motion and correcting for it using PET data alone [11]; however, this can be limited for several reasons: (a) PET images acquired or gated over the short time frames necessary to capture motion are usually too noisy to employ non-rigid registrations [12]; (b) For tracers with rapid kinetics, the radioactivity varies significantly with time, depending on the physiological response of the patient to the tracer [13]; (c) For attenuation correction (AC) of PET images, AC factors need to be accurately registered with each PET position [14]; (d) PET has limited axial field of view (FoV) and cannot measure motion at the edges. A possible alternative approach that can be used to avoid these limitations is the use of a combined PET-MR scanner [15] capable of simultaneous PET and MR acquisition.…”