This article presents a brief overview of the development of high-resolution SPECT for small-animal im- aging. A pinhole collimator has been used for high-resolution animal SPECT to provide better spatial resolution a...This article presents a brief overview of the development of high-resolution SPECT for small-animal im- aging. A pinhole collimator has been used for high-resolution animal SPECT to provide better spatial resolution and detection efficiency in comparison with a parallel-hole collimator. The theory of imaging characteristics of the pin- hole collimator is presented and the designs of the pinhole aperture are discussed. The detector technologies used for the development of small-animal SPECT and the recent advances are presented. The evolving trend of small-animal SPECT is toward a multi-pinhole and a multi-detector system to obtain a high resolution and also a high detection ef- ficiency.展开更多
Ex vivo lung perfusion(EVLP) is a powerful experimental model for isolated lung research. EVLP allows for the lungs to be manipulated and characterized in an external environment so that the effect of specific ventila...Ex vivo lung perfusion(EVLP) is a powerful experimental model for isolated lung research. EVLP allows for the lungs to be manipulated and characterized in an external environment so that the effect of specific ventilation/perfusion variables can be studied independent of other confounding physiologic contributions. At the same time,EVLP allows for normal organ level function and real-time monitoring of pulmonary physiology and mechanics. As a result,this technique provides uniqueadvantages over in vivo and in vitro models. Small and large animal models of EVLP have been developed and each of these models has their strengths and weaknesses. In this manuscript,we provide insight into the relative strengths of each model and describe how the development of advanced EVLP protocols is leading to a novel experimental platform that can be used to answer critical questions in pulmonary physiology and transplant medicine.展开更多
Background: Suppression of physiologic myocardial sequestration of glucose, and hence the 2-deoxy-18 fluorodeoxyglucose (FDG) is of critical importance to effectively evaluate intrinsic cardiac pathology and better de...Background: Suppression of physiologic myocardial sequestration of glucose, and hence the 2-deoxy-18 fluorodeoxyglucose (FDG) is of critical importance to effectively evaluate intrinsic cardiac pathology and better delineate extra- cardiac FDG activity on Positron Emission Tomography (PET) imaging. In a rodent model, we studied the effect of duration of fasting with or without high fat diet (HFD) consumption on myocardial FDG uptake. Methods: 9 Sprague- Dawley rats underwent four different preparation protocols before obtaining micro PET imaging: Non-fasting (NF), 18-hrs/Prolonged fasting (PF), 12-hrs/Short fasting followed by High Fat Diet (SF-HFD) and 18-hrs/Prolonged fasting followed by High Fat Diet (PF-HFD). Region of interest were drawn on the myocardium (heart) and ascending aorta (blood pool) to generate maximum standard uptake values (SUVm) for the heart (H-SUVm) and blood pool (BP- SUVm). Results: PF-HFD and SF-HFD preparation protocols resulted in significantly lower H-SUVm as compared to PF and NF protocols with H-SUVm of 1.49, 1.56, 4.38 and 10.19 respectively. Conclusion: PF-HFD and SF-HFD preparation protocols provide superior suppression of myocardial FDG uptake in comparison to PF and NF protocols. These findings offer an approach to study intrinsic cardiac disorders (vascular, infiltrative etc) and also provide better visualization of extra-cardiac pathologic disorders.展开更多
Background: Hemophilic arthropathy is a debilitating morbidity of hemophilia caused by recurrent joint bleeds. We investigated if the joint bleed volume, before initiation of treatment, was linked to the subsequent de...Background: Hemophilic arthropathy is a debilitating morbidity of hemophilia caused by recurrent joint bleeds. We investigated if the joint bleed volume, before initiation of treatment, was linked to the subsequent degree of histopathological changes and the development of bone pathology in a mouse model of hemophilic arthropathy.Methods: FVIII knock-out(F8-KO) mice were dosed with a micro-CT blood pool agent prior to induction of hemarthrosis. Eight hours after induction, the bleed volume was quantified with micro computed tomography(micro-CT) and recombinant FVIII treatment initiated. On Day 8, inflammation in the knees was characterized by fluorescence molecular tomography. On Day 14, knee pathology was characterized by micro-CT and histopathology. In a second study, contrast agent was injected into the knee of wild-type(WT) mice, followed by histopathological evaluation on Day 14.Results: The average joint bleed volume before treatment was 3.9 mm3. The inflammation-related fluorescent intensities in the injured knees were significantly increased on Day 8. The injured knees had significantly increased synovitis scores, vessel counts, and areas of hemosiderin compared to un-injured knees. However, no cartilage-or bone pathology was observed. The bleed volume before initiation of treatment correlated with the degree of synovitis and was associated with high fluorescent intensity on Day 8. In F8-KO and WT mice, persistence of contrast agent in the joint elicited morphological changes.Conclusion: When applying a delayed on-demand treatment regimen to hemophilic mice subjected to an induced knee hemarthrosis, the degree of histopathological changes on Day 14 reflected the bleed volume prior to initiation of treatment.展开更多
Spontaneous light emission from living animals can overcome the investigated light signals in small animal luminescence imaging. Despite autofluorescence emission is well studied the spontaneous luminescence backgroun...Spontaneous light emission from living animals can overcome the investigated light signals in small animal luminescence imaging. Despite autofluorescence emission is well studied the spontaneous luminescence background is less known and its importance is growing due to the new born imaging techniques like Cerenkov Luminescence Imaging and Radionuclide Luminescence Imaging in which faint sources are often involved. In order to investigate the spontaneous emission we studied the background luminescence in vivo from health Nu/Nu mice in optical imaging acquisitions and we related it with the optical properties of the diet of the animals. In particular luminescence images of mice feed with normal diet used in animal facilities were acquired using a commercial optical imager. The intensity and the spectral features of the luminescence emission from the animal surface after sunshine exposition and after normal lighting laboratory conditions were measured. The same was done with the pellets of food used to feed the animals. We found a background emission from the entire animal surface and localized light sources in the abdominal/lumbar region. Their intensity can be modulated by the light exposition of the animals before the imaging session and decreases along the time when they are put in darkness. The comparison of the luminescence time decay of animals and pellets suggests that the light sources are related to the persistent luminescence of the molecules contained in the food. So ambient exposure before imaging is important for luminescence imaging in order to keep down the background. The optical properties of food are also important and it necessary to check them before to feed the animals not only in fluorescence imaging but also in luminescence imaging.展开更多
文摘This article presents a brief overview of the development of high-resolution SPECT for small-animal im- aging. A pinhole collimator has been used for high-resolution animal SPECT to provide better spatial resolution and detection efficiency in comparison with a parallel-hole collimator. The theory of imaging characteristics of the pin- hole collimator is presented and the designs of the pinhole aperture are discussed. The detector technologies used for the development of small-animal SPECT and the recent advances are presented. The evolving trend of small-animal SPECT is toward a multi-pinhole and a multi-detector system to obtain a high resolution and also a high detection ef- ficiency.
文摘Ex vivo lung perfusion(EVLP) is a powerful experimental model for isolated lung research. EVLP allows for the lungs to be manipulated and characterized in an external environment so that the effect of specific ventilation/perfusion variables can be studied independent of other confounding physiologic contributions. At the same time,EVLP allows for normal organ level function and real-time monitoring of pulmonary physiology and mechanics. As a result,this technique provides uniqueadvantages over in vivo and in vitro models. Small and large animal models of EVLP have been developed and each of these models has their strengths and weaknesses. In this manuscript,we provide insight into the relative strengths of each model and describe how the development of advanced EVLP protocols is leading to a novel experimental platform that can be used to answer critical questions in pulmonary physiology and transplant medicine.
文摘Background: Suppression of physiologic myocardial sequestration of glucose, and hence the 2-deoxy-18 fluorodeoxyglucose (FDG) is of critical importance to effectively evaluate intrinsic cardiac pathology and better delineate extra- cardiac FDG activity on Positron Emission Tomography (PET) imaging. In a rodent model, we studied the effect of duration of fasting with or without high fat diet (HFD) consumption on myocardial FDG uptake. Methods: 9 Sprague- Dawley rats underwent four different preparation protocols before obtaining micro PET imaging: Non-fasting (NF), 18-hrs/Prolonged fasting (PF), 12-hrs/Short fasting followed by High Fat Diet (SF-HFD) and 18-hrs/Prolonged fasting followed by High Fat Diet (PF-HFD). Region of interest were drawn on the myocardium (heart) and ascending aorta (blood pool) to generate maximum standard uptake values (SUVm) for the heart (H-SUVm) and blood pool (BP- SUVm). Results: PF-HFD and SF-HFD preparation protocols resulted in significantly lower H-SUVm as compared to PF and NF protocols with H-SUVm of 1.49, 1.56, 4.38 and 10.19 respectively. Conclusion: PF-HFD and SF-HFD preparation protocols provide superior suppression of myocardial FDG uptake in comparison to PF and NF protocols. These findings offer an approach to study intrinsic cardiac disorders (vascular, infiltrative etc) and also provide better visualization of extra-cardiac pathologic disorders.
文摘Background: Hemophilic arthropathy is a debilitating morbidity of hemophilia caused by recurrent joint bleeds. We investigated if the joint bleed volume, before initiation of treatment, was linked to the subsequent degree of histopathological changes and the development of bone pathology in a mouse model of hemophilic arthropathy.Methods: FVIII knock-out(F8-KO) mice were dosed with a micro-CT blood pool agent prior to induction of hemarthrosis. Eight hours after induction, the bleed volume was quantified with micro computed tomography(micro-CT) and recombinant FVIII treatment initiated. On Day 8, inflammation in the knees was characterized by fluorescence molecular tomography. On Day 14, knee pathology was characterized by micro-CT and histopathology. In a second study, contrast agent was injected into the knee of wild-type(WT) mice, followed by histopathological evaluation on Day 14.Results: The average joint bleed volume before treatment was 3.9 mm3. The inflammation-related fluorescent intensities in the injured knees were significantly increased on Day 8. The injured knees had significantly increased synovitis scores, vessel counts, and areas of hemosiderin compared to un-injured knees. However, no cartilage-or bone pathology was observed. The bleed volume before initiation of treatment correlated with the degree of synovitis and was associated with high fluorescent intensity on Day 8. In F8-KO and WT mice, persistence of contrast agent in the joint elicited morphological changes.Conclusion: When applying a delayed on-demand treatment regimen to hemophilic mice subjected to an induced knee hemarthrosis, the degree of histopathological changes on Day 14 reflected the bleed volume prior to initiation of treatment.
文摘Spontaneous light emission from living animals can overcome the investigated light signals in small animal luminescence imaging. Despite autofluorescence emission is well studied the spontaneous luminescence background is less known and its importance is growing due to the new born imaging techniques like Cerenkov Luminescence Imaging and Radionuclide Luminescence Imaging in which faint sources are often involved. In order to investigate the spontaneous emission we studied the background luminescence in vivo from health Nu/Nu mice in optical imaging acquisitions and we related it with the optical properties of the diet of the animals. In particular luminescence images of mice feed with normal diet used in animal facilities were acquired using a commercial optical imager. The intensity and the spectral features of the luminescence emission from the animal surface after sunshine exposition and after normal lighting laboratory conditions were measured. The same was done with the pellets of food used to feed the animals. We found a background emission from the entire animal surface and localized light sources in the abdominal/lumbar region. Their intensity can be modulated by the light exposition of the animals before the imaging session and decreases along the time when they are put in darkness. The comparison of the luminescence time decay of animals and pellets suggests that the light sources are related to the persistent luminescence of the molecules contained in the food. So ambient exposure before imaging is important for luminescence imaging in order to keep down the background. The optical properties of food are also important and it necessary to check them before to feed the animals not only in fluorescence imaging but also in luminescence imaging.
