Nonlinear motion correction of respiratory-gated lung SPECT images

Abstract

We propose a method for correcting the motion of the lungs between different phase images obtained by respiratory-gated single photon emission computed tomography (SPECT). This method is applied to SPECT images that show a preserved activity distribution in the lungs such as 99m-Tc macro aggregated albumin (99m-Tc-MAA) perfusion images and 99m-Tc-Technegas ventilation images. In the proposed method, an objective function, which consists of both the degree of similarity between a reference image and a deformed image, and the smoothness of deformation is defined and optimized using a simulated annealing algorithm. For the degree of similarity term in the objective function, an expansion ratio, defined as the ratio of change in local volume due to deformation, is introduced to preserve the total activity during the motion correction process. This method was applied to data simulated from computer phantoms, data acquired from a physical phantom, and 17 sets of clinical data. In all cases, the motion correction between inspiration and expiration phase images was successfully achieved.

Semi-quantitation of pulmonary perfusion heterogeneity on respiratory-gated inspiratory and expiratory perfusion SPECT in patients with pulmonary emphysema

“…This gated SPECT also provides inspiratory and expiratory SPECT. FLVR curve analysis on these two SPECT may contribute to semi-quantitation of respiratory change of PPH in PE because the degree of PPH should be signifi cantly changed according to respiratory lung volume changes [4,5,11]. In this study, we validated the utility of FLVR curve analysis on gated SPECT in the semi-quantitative assessment of PPH in PE patients.…”

“…The dissociation from the normal standard FLVR curve (red line) is more prominent in the expiratory curve compared with that in the inspiratory curve tory cycles and the cyclically changing lung volume inherently obscure PPH [6][7][8][9][10][11]. The enhanced PPH on gated SPECT is also explained by alteration of radioactivity per unit lung volume and the size of defects because of respiratory lung volume changes [6][7][8][9][10][11]. PPH should be signifi cantly altered between inspiratory and expiratory SPECT in emphysematous lungs with heterogeneous air trapping [15][16][17][18][19][20].…”

“…The recently developed, respiratory-gated perfusion SPECT can reduce such adverse respiratory lung motion effects on conventional SPECT [8][9][10][11]. This gated SPECT also provides inspiratory and expiratory SPECT.…”

Accuracy of respiratory motion measurement of 4D-MRI: A comparison between cine and sequential acquisition

“…[4][5][6] In particular, 4D-CT can be used to determine patient-specific internal target volume (ITV) and the optimal motion management strategy for the patient. 7 Furthermore, respiratory-gated techniques were also developed to assisted motion management, used in imaging techniques (such as respiratory-gated PET/SPECT) [8][9][10] and therapy techniques. Recently, 4D magnetic resonance imaging (4D-MRI) has been developed for imaging respiratory motion for abdominal cancers, [11][12][13][14] owning to its high soft-tissue contrast and no-known ionizing radiation hazard.…”

Surface-Based Respiratory Motion Classification and Verification

“…To minimize damnification of healthy tissue during treatment sessions techniques like gating or tumor tracking [1,2] are applied. For so called external gating an adaptive surrogate respiratory signal is used to represent the patient's breathing over time as there is a correlation between the actual tumor movement and the patient's respiration [3].…”