Correlation of FAPI PET Uptake with Immunohistochemistry in Explanted Lungs from Patients with Advanced Interstitial Lung Disease.

Recent studies have demonstrated promising results of fibroblast activation protein (FAP) inhibitor (FAPI) PET in prognosticating and monitoring interstitial lung diseases (ILDs). As a first step toward successful translation, our primary aim was to validate the FAPI PET uptake through immunohistochemistry in patients with advanced ILD who underwent lung transplantation after a FAPI PET scan. This is a preliminary analysis of a single-center, open-label, single-arm, prospective exploratory biodistribution study of Ga-FAPI-46 PET imaging in patients with ILD (NCT05365802).

Retinal tissue oxygen tension and consumption during light flicker stimulation in rat.

Light flicker stimulation has been shown to increase inner retinal oxygen metabolism and supply. The purpose of the study was to test the hypothesis that sustained light flicker stimulation of various durations alters the depth profile metrics of oxygen partial pressure in the retinal tissue (tPO) but not the outer retinal oxygen consumption rate (QO). In 17 rats, tPO depth profiles were derived by phosphorescence lifetime imaging after intravitreal injection of an oxyphor.

A method for volumetric retinal tissue oxygen tension imaging.

Purpose: Inadequate retinal oxygenation occurs in many vision-threatening retinal diseases, including diabetic retinopathy, retinal vascular occlusions, and age-related macular degeneration. Therefore, techniques that assess retinal oxygenation are necessary to understand retinal physiology in health and disease. The purpose of the current study is to report a method for the three-dimensional (3D) imaging of retinal tissue oxygen tension (tPO) in rats.

The effect of intravitreal vascular endothelial growth factor on inner retinal oxygen delivery and metabolism in rats.

Vascular endothelial growth factor (VEGF) is stimulated by hypoxia and plays an important role in pathologic vascular leakage and neovascularization. Increased VEGF may affect inner retinal oxygen delivery (DO2) and oxygen metabolism (MO2), however, quantitative information is lacking. We tested the hypotheses that VEGF increases DO2, but does not alter MO2.

Response of inner retinal oxygen extraction fraction to light flicker under normoxia and hypoxia in rat.

Purpose: Oxygen extraction fraction (OEF), defined by the ratio of oxygen metabolism (MO2) to delivery (DO2), determines the level of compensation of MO2 by DO2. In the current study, we tested the hypothesis that inner retinal OEF remains unchanged during light flicker under systemic normoxia and hypoxia in rats due to the matching of MO2 and DO2.

Methods: Retinal vascular oxygen tension (PO2) measurements were obtained in 10 rats by phosphorescence lifetime imaging.

Correspondence of retinal thinning and vasculopathy in mice with oxygen-induced retinopathy.

The aberrantly vascularized peripheral retina in retinopathy of prematurity (ROP) may be associated with visual field constriction, retinal dysfunction, and abnormalities in retinal thickness which is commonly assessed by spectral domain optical coherence tomography (SDOCT). However, due to the limitation of SDOCT for peripheral retinal imaging, retinal thickness in avascular peripheral retina in ROP has not been evaluated. Oxygen induced retinopathy (OIR) in mice has features of vasculopathy similar to those in human ROP.

Inner retinal oxygen delivery and metabolism in streptozotocin diabetic rats.

Purpose: The purpose of the study is to report global measurements of inner retinal oxygen delivery (DO2_IR) and oxygen metabolism (MO2_IR) in streptozotocin (STZ) diabetic rats.

Methods: Phosphorescence lifetime and blood flow imaging were performed in rats 4 (STZ/4 wk; n = 10) and 6 (STZ/6 wk; n = 10) weeks following injection of STZ to measure retinal arterial (O2A) and venous (O2V) oxygen contents and total retinal blood flow (F). DO2_IR and MO2_IR were calculated from measurements of F and O2A and of F and the arteriovenous oxygen content difference, respectively.

In vivo retinal vascular oxygen tension imaging and fluorescein angiography in the mouse model of oxygen-induced retinopathy.

Purpose: Oxygenation abnormalities are implicated in the development of retinopathy of prematurity (ROP). The purpose of this study is to report in vivo retinal vascular oxygen tension (PO2) measurements and fluorescein angiography (FA) findings in the mouse model of oxygen-induced retinopathy (OIR).

Methods: We exposed 19 neonatal mice to 77% oxygen from postnatal day 7 (P7) to P12 (OIR), while 11 neonatal mice were kept under room air (control).

Inner retinal oxygen delivery and metabolism under normoxia and hypoxia in rat.

Purpose: Retinal hypoxia is a common pathological condition usually caused by ischemia that may result in alterations in oxidative energy metabolism. We report measurements of oxygen delivery by the retinal circulation (DO2_IR) and inner retinal oxygen metabolism (MO2_IR) under systemic normoxia and hypoxia in rat.

Methods: Rats were ventilated with fractions of inspired oxygen (FiO2) to induce either normoxia (n = 10), moderate hypoxia (n = 14), or severe hypoxia (n = 10).

Inner retinal oxygen extraction fraction in rat.

Purpose: Oxygen extraction fraction (OEF), defined by the ratio of oxygen consumption to delivery, may be a useful parameter for assessing the retinal tissue status under impaired circulation. We report a method for measurement of inner retinal OEF in rats under normoxia and hypoxia based on vascular oxygen tension (PO(2)) imaging.

Methods: Retinal vascular PO(2) measurements were obtained in 10 rats, using our previously developed optical section phosphorescence lifetime imaging system.

Feasibility of conjunctival hemodynamic measurements in rabbits: reproducibility, validity, and response to acute hypotension.

Objective: To evaluate the feasibility of conjunctival hemodynamic measurements based on assessment of reproducibility, validity, and response to acute hypotension.

Methods: Image sequences of the conjunctival microvasculature of rabbits were captured using a slit lamp biomicroscope under a steady-state condition, after topical administration of phenylephrine, and after intravenous administration of esmolol. Venous hemodynamic parameters (diameter, blood velocity, blood flow, and wall shear stress) were derived.

Oxygen tension and gradient measurements in the retinal microvasculature of rats.

Background: Oxygen delivery from the retinal vasculature plays a crucial role in maintaining normal retinal metabolic function. Therefore, measurements of retinal vascular oxygen tension (PO(2)) and PO(2) longitudinal gradients (gPO(2)) along retinal blood vessels may help gain fundamental knowledge of retinal physiology and pathological processes.

Methods: Three-dimensional retinal vascular PO(2) maps were generated in rats by optical section phosphorescence lifetime imaging.

Inner retinal metabolic rate of oxygen by oxygen tension and blood flow imaging in rat.

The metabolic function of inner retinal cells relies on the availability of nutrients and oxygen that are supplied by the retinal circulation. Assessment of retinal tissue vitality and function requires knowledge of both the rate of oxygen delivery and consumption. The purpose of the current study is to report a novel technique for assessment of the inner retinal metabolic rate of oxygen (MO(2)) by combined measurements of retinal blood flow and vascular oxygen tension (PO(2)) in rat.

Automated prescription of an optimal imaging plane for measurement of cerebral blood flow by phase contrast magnetic resonance imaging.

This study describes and evaluates a semiautomated method for prescribing an optimal imaging plane that is located as close as possible to the skull base, and is simultaneously nearly perpendicular to the four arteries leading blood to the brain [internal carotid arteries (ICAs) and vertebral arteries (VAs)]. Such a method will streamline and improve reliability of the measurement of total cerebral blood flow and intracranial pressure by velocity encoding phase-contrast magnetic resonance imaging. The method first extracts the vessels' centerline from a 2-D time-of-flight magnetic resonance angiogram of the neck by performing distance transformations.

Analysis of the correlation between the facial temperature and the stenosis of carotid arteries.

Death caused by stroke above the age of 60 years placed second in the world, and is the fifth leading cause in people aged 15 to 59 years old. Several methods for early detection of stroke are magnetic resonance angiography, and carotid duplex, both diagnoses are cost and time consuming. This research is aimed to provide a noninvasive, cost effective, and rapid technique for diagnosing carotid artery stenosis by using thermography.