Longitudinal Evaluation of Fatty Acid Metabolism in  Normal and Spontaneously Hypertensive Rat Hearts with  Dynamic MicroSPECT Imaging

Reutter, B.W.; Huesman, R.H.; Brennan, Kathleen; Boutchko, Rostyslav; Hanrahan, Stephen M.; Gullberg, Grant T.

doi:10.1155/2011/893129

Cited by 12 publications

(11 citation statements)

References 41 publications

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“…Our previous longitudinal study using dynamic microSPECT imaging of β-methyl-p- 123 I-iodophenyl-pentadecanoic acid ( 123 I-BMIPP) indicated a higher FA metabolic rate in two control rats, compared with two SHRs, at 14 mo and a general decrease with age in both models (26). Hajri et al also found reduced FA oxidation in the heart of the fasted SHR by comparing the biodistribution of the slowly oxidized FA analog 125 I-BMIPP in WKY controls and SHR (18).…”

Section: Discussionmentioning

confidence: 99%

Longitudinal Evaluation of Left Ventricular Substrate Metabolism, Perfusion, and Dysfunction in the Spontaneously Hypertensive Rat Model of Hypertrophy Using Small-Animal PET/CT Imaging

et al. 2013

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Myocardial metabolic and perfusion imaging is a vital tool for understanding the physiologic consequences of heart failure. We used PET imaging to examine the longitudinal kinetics of 18F-FDG and 14(R,S)-18F-fluoro-6-thia-heptadecanoic acid (18F-FTHA) as analogs of glucose and fatty acid (FA) to quantify metabolic substrate shifts with the spontaneously hypertensive rat (SHR) as a model of left ventricular hypertrophy (LVH) and failure. Myocardial perfusion and left ventricular function were also investigated using a newly developed radiotracer 18F-fluorodihydrorotenol (18F-FDHROL). Methods Longitudinal dynamic electrocardiogram-gated small-animal PET/CT studies were performed with 8 SHR and 8 normotensive Wistar-Kyoto (WKY) rats over their life cycle. We determined the myocardial influx rate constant for 18F-FDG and 18F-FTHA (KiFDG and KiFTHA, respectively) and the wash-in rate constant for 18F-FDHROL (K1FDHROL). 18F-FDHROL data were also used to quantify left ventricular ejection fraction (LVEF) and end-diastolic volume (EDV). Blood samples were drawn to independently measure plasma concentrations of glucose, insulin, and free fatty acids (FFAs). Results KiFDG and KiFTHA were higher in SHRs than WKY rats (P < 3 × 10−8 and 0.005, respectively) independent of age. A decrease in KiFDG with age was evident when models were combined (P = 0.034). The SHR exhibited higher K1FDHROL (P < 5 × 10−6) than the control, with no age-dependent trends in either model (P = 0.058). Glucose plasma concentrations were lower in SHRs than controls (P < 6 × 10−12), with an age-dependent rise for WKY rats (P < 2 × 10−5). Insulin plasma concentrations were higher in SHRs than controls (P < 3 × 10−3), with an age-dependent decrease when models were combined (P = 0.046). FFA levels were similar between models (P = 0.374), but an increase with age was evident only in SHR (P < 7 × 10−6). Conclusion The SHR exhibited alterations in myocardial substrate use at 8 mo characterized by increased glucose and FA utilizations. At 20 mo, the SHR had LVH characterized by decreased LVEF and increased EDV, while simultaneously sustaining higher glucose and similar FA utilizations (compared with WKY rats), which indicates maladaptation of energy substrates in the failing heart. Elevated K1FDHROL in the SHR may reflect elevated oxygen consumption and decreased capillary density in the hypertrophied heart. From our findings, metabolic changes appear to precede mechanical changes of LVH progression in the SHR model.

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Section: Discussionmentioning

confidence: 99%

Longitudinal Evaluation of Left Ventricular Substrate Metabolism, Perfusion, and Dysfunction in the Spontaneously Hypertensive Rat Model of Hypertrophy Using Small-Animal PET/CT Imaging

et al. 2013

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“…Reduced number of unknowns suggests that a point cloud can be a convenient image representation when reconstructing dynamic image data directly from projections. Computational techniques that can benefit from this include factor analysis of dynamic series (Sitek et al 2000) or B-spline based reconstruction with non-uniform pixelation previously applied to dynamic small animal SPECT by our group (Reutter et al 2011). Implementation of the tomographic problem on a discrete mesh makes our approach a convenient starting point for a number of finite element based methods, including modeling of mechanical and other properties of tissues (Sitek et al 2002, Veress et al 2008).…”

Section: Discussionmentioning

confidence: 99%

Practical implementation of tetrahedral mesh reconstruction in emission tomography

Boutchko¹,

Sitek²,

Gullberg³

2013

Phys. Med. Biol.

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This paper presents a practical implementation of image reconstruction on tetrahedral meshes optimized for emission computed tomography with parallel beam geometry. Tetrahedral mesh built on a point cloud is a convenient image representation method, intrinsically three-dimensional and with a multi-level resolution property. Image intensities are defined at the mesh nodes and linearly interpolated inside each tetrahedron. For the given mesh geometry, the intensities can be computed directly from tomographic projections using iterative reconstruction algorithms with a system matrix calculated using an exact analytical formula. The mesh geometry is optimized for a specific patient using a two stage process. First, a noisy image is reconstructed on a finely-spaced uniform cloud. Then, the geometry of the representation is adaptively transformed through boundary-preserving node motion and elimination. Nodes are removed in constant intensity regions, merged along the boundaries, and moved in the direction of the mean local intensity gradient in order to provide higher node density in the boundary regions. Attenuation correction and detector geometric response are included in the system matrix. Once the mesh geometry is optimized, it is used to generate the final system matrix for ML-EM reconstruction of node intensities and for visualization of the reconstructed images. In dynamic PET or SPECT imaging, the system matrix generation procedure is performed using a quasi-static sinogram, generated by summing projection data from multiple time frames. This system matrix is then used to reconstruct the individual time frame projections. Performance of the new method is evaluated by reconstructing simulated projections of the NCAT phantom and the method is then applied to dynamic SPECT phantom and patient studies and to a dynamic microPET rat study. Tetrahedral mesh-based images are compared to the standard voxel-based reconstruction for both high and low signal-to-noise ratio projection datasets. The results demonstrate that the reconstructed images represented as tetrahedral meshes based on point clouds offer image quality comparable to that achievable using a standard voxel grid while allowing substantial reduction in the number of unknown intensities to be reconstructed and reducing the noise.

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“…Each complete rotation consisted of 90 angular frames per detector head acquired every second (2 opposing heads were used). The system parameters and the acquisition protocol for this series of rat experiments are described in more detail in [7] and [8]. Analysis of the penetration and scatter through the pinhole for this system is given in [33].…”

Section: Rat Pinhole Spect Studymentioning

confidence: 99%

“…The use of exponentialbased time functions was proposed in [4], and B-spline basis functions were proposed in [5], [6]. An application of the Bspline approach to dynamic pinhole SPECT is given in [7] and most recently in [8]. Using preset temporal functions has been shown to produce meaningful results; however, the TACs obtained with this method are sometimes oversmoothed, imprecise for some types of input functions, and not always reliable for quantitation purposes.…”

Section: Introductionmentioning

confidence: 99%

Reconstruction of 4-D Dynamic SPECT Images From Inconsistent Projections Using a Spline Initialized FADS Algorithm (SIFADS)

Abdalah

Boutchko

Mitra

et al. 2015

IEEE Trans. Med. Imaging

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In this paper, we propose and validate an algorithm of extracting voxel-by-voxel time activity curves directly from inconsistent projections applied in dynamic cardiac SPECT. The algorithm was derived based on factor analysis of dynamic structures (FADS) approach and imposes prior information by applying several regularization functions with adaptively changing relative weighting. The anatomical information of the imaged subject was used to apply the proposed regularization functions adaptively in the spatial domain. The algorithm performance is validated by reconstructing dynamic datasets simulated using the NCAT phantom with a range of different input tissue time-activity curves. The results are compared to the spline-based and FADS methods. The validated algorithm is then applied to reconstruct pre-clinical cardiac SPECT data from canine and murine subjects. Images, generated from both simulated and experimentally acquired data confirm the ability of the new algorithm to solve the inverse problem of dynamic SPECT with slow gantry rotation.

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Longitudinal Evaluation of Fatty Acid Metabolism in Normal and Spontaneously Hypertensive Rat Hearts with Dynamic MicroSPECT Imaging

Cited by 12 publications

References 41 publications

Longitudinal Evaluation of Left Ventricular Substrate Metabolism, Perfusion, and Dysfunction in the Spontaneously Hypertensive Rat Model of Hypertrophy Using Small-Animal PET/CT Imaging

Longitudinal Evaluation of Left Ventricular Substrate Metabolism, Perfusion, and Dysfunction in the Spontaneously Hypertensive Rat Model of Hypertrophy Using Small-Animal PET/CT Imaging

Practical implementation of tetrahedral mesh reconstruction in emission tomography

Reconstruction of 4-D Dynamic SPECT Images From Inconsistent Projections Using a Spline Initialized FADS Algorithm (SIFADS)

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