A realistic spline-based dynamic heart phantom

Segars, W. Paul; Lalush, David S.; Tsui, B.M.W.

doi:10.1109/23.775570

Cited by 246 publications

(132 citation statements)

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“…Time-dependent activity concentrations were generated using a compartmental model (Fig. 1, Table I), and then assigned to anatomical regions obtained from the NCAT [4] digital phantom. A 370 MBq injection was simulated, with 20% going to the renal system and the rest distributed evenly as background.…”

Section: Methodsmentioning

confidence: 99%

Segmentation-based regularization of dynamic SPECT reconstruction

Humphries

Saad

Celler

et al. 2009

2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)

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Abstract-Dynamic SPECT reconstruction using a single slow camera rotation is a highly underdetermined problem, which requires the use of regularization techniques to obtain useful results. The dSPECT algorithm (Farncombe et al. 1999) provides temporal but not spatial regularization, resulting in poor contrast and low activity levels in organs of interest, due mostly to blurring. In this paper we incorporate a user-assisted segmentation algorithm (Saad et al. 2008) into the reconstruction process to improve the results. Following an initial reconstruction using the existing dSPECT technique, a user places seeds in the image to indicate regions of interest (ROIs). A random-walk based automatic segmentation algorithm then assigns every voxel in the image to one of the ROIs, based on its proximity to the seeds as well as the similarity between time activity curves (TACs). The user is then able to visualize the segmentation and improve it if necessary. Average TACs are extracted from each ROI and assigned to every voxel in the ROI, giving an image with a spatially uniform TAC in each ROI. This image is then used as initial input to a second run of dSPECT, in order to adjust the dynamic image to better fit the projection data.We test this approach with a digital phantom simulating the kinetics of Tc99m-DTPA in the renal system, including healthy and unhealthy behaviour. Summed TACs for each kidney and the bladder were calculated for the spatially regularized and nonregularized reconstructions, and compared to the true values. The TACs for the two kidneys were noticeably improved in every case, while TACs for the smaller bladder region were unchanged. Furthermore, in two cases where the segmentation was intentionally done incorrectly, the spatially regularized reconstructions were still as good as the non-regularized ones. In general, the segmentation-based regularization improves TAC quality within ROIs, as well as image contrast.

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Section: Methodsmentioning

confidence: 99%

Segmentation-based regularization of dynamic SPECT reconstruction

Humphries

Saad

Celler

et al. 2009

2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)

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“…A 4D NURBS model of the beating heart was incorporated from a previous study [14]. The spline-based MCAT phantom can model organ shape and anatomical variations and patient motion more realistically than the current MCAT phantom.…”

Section: Introductionmentioning

confidence: 99%

“…Also, NURBS can be altered easily via affine and other transformations to model variations in anatomy among patients. The particular transformation needs only to be applied to the set of control points through a matrix multiplication [13,14].…”

Section: Introductionmentioning

confidence: 99%

Modeling respiratory mechanics in the MCAT and spline-based MCAT phantoms

Segars

Lalush

Tsui³

2001

IEEE Trans. Nucl. Sci.

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211

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Respiratory motion can cause artifacts in myocardial SPECT. We incorporate respiratory mechanics into the current 4D MCAT and into the next generation spline-based MCAT phantoms. In order to simulate respiratory motion in the current MCAT phantom, the geometric solids for the diaphragm, heart, ribs, and lungs were altered through manipulation of parameters defining them. Affine transformations were applied to the control points defining the same respiratory structures in the spline-based MCAT phantom to simulate respiratory motion. The NURBS surfaces for the lungs and body outline were constructed in such a way as to be linked to the surrounding ribs. Expansion and contraction of the thoracic cage then coincided with expansion and contraction of the lungs and body. The changes both phantoms underwent were splined over time to create time continuous 4D respiratory models. We conclude that both respiratory models are effective tools for researching effects of respiratory motion.

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“…Also, this phantom will be virtually imaged by using modality simulators (Positron Emission Tomography, MRI...) Error! Reference source not found., [10]. Simulating various heart dynamics can be achieved either by adequately tuning the model's parameters (control points) or processing additional examinations for healthy volunteers and pathological subjects.…”

Section: Discussionmentioning

confidence: 99%