Adaptation of the modified Bouc–Wen model to compensate for hysteresis in respiratory motion for the list‐mode binning of cardiac SPECT and PET acquisitions: Testing using MRI

Abstract

Purpose: Binning list-mode acquisitions as a function of a surrogate signal related to respiration has been employed to reduce the impact of respiratory motion on image quality in cardiac emission tomography (SPECT and PET). Inherent in amplitude binning is the assumption that there is a monotonic relationship between the amplitude of the surrogate signal and respiratory motion of the heart. This assumption is not valid in the presence of hysteresis when heart motion exhibits a different relationship with the surrogate during inspiration and expiration. The purpose of this study was to investigate the novel approach of using the Bouc-Wen (BW) model to provide a signal accounting for hysteresis when binning list-mode data with the goal of thereby improving motion correction. The study is based on the authors' previous observations that hysteresis between chest and abdomen markers was indicative of hysteresis between abdomen markers and the internal motion of the heart. Methods: In 19 healthy volunteers, they determined the internal motion of the heart and diaphragm in the superior-inferior direction during free breathing using MRI navigators. A visual tracking system () synchronized with MRI acquisition tracked the anterior-posterior motions of external markers placed on the chest and abdomen. These data were employed to develop and test the Bouc-Wen model by inputting the  derived chest and abdomen motions into it and using the resulting output signals as surrogates for cardiac motion. The data of the volunteers were divided into training and testing sets. The training set was used to obtain initial values for the model parameters for all of the volunteers in the set, and for set members based on whether they were or were not classified as exhibiting hysteresis using a metric derived from the markers. These initial parameters were then employed with the testing set to estimate output signals. Pearson's linear correlation coefficient between the abdomen, chest, average of chest and abdomen markers, and Bouc-Wen derived signals versus the true internal motion of the heart from MRI was used to judge the signals match to the heart motion. Results: The results show that the Bouc-Wen model generated signals demonstrated strong correlation with the heart motion. This correlation was slightly larger on average than that of the external surrogate signals derived from the abdomen marker, and average of the abdomen and chest markers, but was not statistically significantly different from them. Conclusions: The results suggest that the proposed model has the potential to be a unified framework for modeling hysteresis in respiratory motion in cardiac perfusion studies and beyond. C 2014 American Association of Physicists in Medicine. [http://dx

Correction of hysteretic respiratory motion in SPECT myocardial perfusion imaging: Simulation and patient studies

“…More details on the BW model, such as how we used a set of human volunteer simultaneous MRI and VTS studies to determine the initial parameters of the model, and how these parameters were used with the VTS signal to estimate , can be found in …”

“…For the clinical studies, the following two surrogate signals were considered: (a) the external abdomen marker and (b) the BW model. Note that the chest signal acquired was employed in BW model but not in performing amplitude‐binning RM correction due to its low magnitude, susceptibility to body motion, and being found to have a lower correlation with the navigator measured heart motion than the abdomen signal in the majority of a combined group of 19 volunteers previously reported . There is no “truth” to compare against with patient data.…”

“…In our previous work, we investigated a method for correcting respiratory hysteresis by applying the Bouc–Wen (BW) model without the need for shape prior, pre‐scans, or phase‐offsets. The model uses first‐order nonlinear differential equations to account for the hysteretic motion occurring between the inspiration and expiration phases .…”

Improving the Spatial Alignment in PET/CT Using Amplitude-Based Respiration-Gated PET and Respiration-Triggered CT

“…3). This might be caused by the respiratory tracking method, using a pressure sensor in a belt located around the patient's abdomen (22). Movement of the different areas in the thorax, however, is more complex and cannot be accurately measured with 1 abdominal belt sensor (Fig.…”

Advances in dual respiratory and ECG-gated SPECT imaging

“…21 Recently pulmonary hysteresis motion has been studied by nuclear imaging, 19 but this is a relatively recent development, which previously had been investigated mainly by way of cardiac MRI. 22,23 While the intent of the current article is to present a method to account for pulmonary effects on SPECT studies that are used to assess LV asynchrony, 1 a tantalizing prospect is that dual-gating methods now being developed may offer the prospect of investigating disease processes involving both aberrant pulmonary and cardiac function. 24 Echocardiography has been used to investigate cases of pulmonary edema induced by RV pacing, 25 and cardiac MRI has been used to detect inter-ventricular asynchrony resulting from primary arterial hypertension.…”