Simultaneous estimation of a model-derived input function for quantifying cerebral glucose metabolism with [F]FDG PET.

Background: Quantification of the cerebral metabolic rate of glucose (CMRGlu) by dynamic [F]FDG PET requires invasive arterial sampling. Alternatives to using an arterial input function (AIF) include the simultaneous estimation (SIME) approach, which models the image-derived input function (IDIF) by a series of exponentials with coefficients obtained by fitting time activity curves (TACs) from multiple volumes-of-interest. A limitation of SIME is the assumption that the input function can be modelled accurately by a series of exponentials.

Aiming for [F]FDG-PET acquisition time reduction in clinical practice for neurological patients.

Purpose: Positron emission tomography (PET) imaging with [F]FDG provides valuable information regarding the underlying pathological processes in neurodegenerative disorders. PET imaging for these populations should be as short as possible to limit head movements and improve comfort. This study aimed to validate an optimized [F]FDG-PET image reconstruction protocol aiming to reduce acquisition time while maintaining adequate quantification accuracy and image quality.

Development of a minimally invasive simultaneous estimation method for quantifying translocator protein binding with [F]FEPPA positron emission tomography.

Background: The purpose of this study was to assess the feasibility of using a minimally invasive simultaneous estimation method (SIME) to quantify the binding of the 18-kDa translocator protein tracer [F]FEPPA. Arterial sampling was avoided by extracting an image-derived input function (IDIF) that was metabolite-corrected using venous blood samples. The possibility of reducing scan duration to 90 min from the recommended 2-3 h was investigated by assuming a uniform non-displaceable distribution volume (V) to simplify the SIME fitting.

Noninvasive Quantification of Cerebral Blood Flow Using Hybrid PET/MR Imaging to Extract the [ O]H O Image-Derived Input Function Free of Partial Volume Errors.

Background: Quantification of cerebral blood flow (CBF) with [ O]H O-positron emission tomography (PET) requires arterial sampling to measure the input function. This invasive procedure can be avoided by extracting an image-derived input function (IDIF); however, IDIFs are sensitive to partial volume errors due to the limited spatial resolution of PET.

Purpose: To present an alternative hybrid PET/MR imaging of CBF (PMRFlow ) that uses phase-contrast (PC) MRI measurements of whole-brain (WB) CBF to calibrate an IDIF extracted from a WB [ O]H O time-activity curve.

Concordance of regional hypoperfusion by pCASL MRI and O-water PET in frontotemporal dementia: Is pCASL an efficacious alternative?

Background: Clinical diagnosis of frontotemporal dementia (FTD) remains a challenge due to the overlap of symptoms among FTD subtypes and with other psychiatric disorders. Perfusion imaging by arterial spin labeling (ASL) is a promising non-invasive alternative to established PET techniques; however, its sensitivity to imaging parameters can hinder its ability to detect perfusion abnormalities.

Purpose: This study evaluated the similarity of regional hypoperfusion patterns detected by ASL relative to the gold standard for imaging perfusion, PET with radiolabeled water (O-water).

Sensitivity of Arterial Spin Labeling for Characterization of Longitudinal Perfusion Changes in Frontotemporal Dementia and Related Disorders.

Background: Advances in the understanding of the pathophysiology of frontotemporal dementia (FTD) and related disorders, along with the development of novel candidate disease modifying treatments, have stimulated the need for tools to assess the efficacy of new therapies. While perfusion imaging by arterial spin labeling (ASL) is an attractive approach for longitudinal imaging biomarkers of neurodegeneration, sources of variability between sessions including arterial transit times (ATT) and fluctuations in resting perfusion can reduce its sensitivity. Establishing the magnitude of perfusion changes that can be reliably detected is necessary to delineate longitudinal perfusion changes related to disease processes from the effects of these sources of error.

A Noninvasive Method for Quantifying Cerebral Metabolic Rate of Oxygen by Hybrid PET/MRI: Validation in a Porcine Model.

The gold standard for imaging the cerebral metabolic rate of oxygen (CMRO) is positron emission tomography (PET); however, it is an invasive and complex procedure that also requires correction for recirculating O-HO and the blood-borne activity. We propose a noninvasive reference-based hybrid PET/magnetic resonance imaging (MRI) method that uses functional MRI techniques to calibrate O-O-PET data. Here, PET/MR imaging of oxidative metabolism (PMROx) was validated in an animal model by comparison to PET-alone measurements.

A non-invasive reference-based method for imaging the cerebral metabolic rate of oxygen by PET/MR: theory and error analysis.

Positron emission tomography (PET) remains the gold standard for quantitative imaging of the cerebral metabolic rate of oxygen (CMRO); however, it is an invasive and complex procedure that requires accounting for recirculating [O]HO (RW) and the cerebral blood volume (CBV). This study presents a non-invasive reference-based technique for imaging CMRO that was developed for PET/magnetic resonance imaging (MRI) with the goal of simplifying the PET procedure while maintaining its ability to quantify metabolism. The approach is to use whole-brain (WB) measurements of oxygen extraction fraction (OEF) and cerebral blood flow (CBF) to calibrate [O]O-PET data, thereby avoiding the need for invasive arterial sampling.