Correction of partial volume effect in 18F-FDG PET brain studies using coregistered MR volumes: Voxel based analysis of tracer uptake in the white matter

Background Huntington’s disease (HD) is an inherited, progressive neurodegenerative disease that has no cure. Striatal atrophy and hypometabolism has been described in HD as far as 15 years before clinical onset and therefore structural and functional imaging biomarkers are the most applied biomarker modalities which call for these to be exact; however, most studies are not considering the partial volume effect and thereby tend to overestimate metabolic reductions, which may bias imaging outcome measures of interventions. Objective Evaluation of partial volume effects in a cohort of premanifest HD gene-expansion carriers (HDGECs). Methods 21 HDGECs and 17 controls had a hybrid 2-[18F]FDG PET/MRI scan performed. Volume measurements and striatal metabolism, both corrected and uncorrected for partial volume effect were correlated to an estimate of disease burden, the CAG age product scaled (CAPS). Results We found significantly reduced striatal metabolism in HDGECs, but not in striatal volume. There was a negative correlation between the CAPS and striatal metabolism, both corrected and uncorrected for the partial volume effect. The partial volume effect was largest in the smallest structures and increased the difference in metabolism between the HDGEC with high and low CAPS scores. Statistical parametric mapping confirmed the results. Conclusions A hybrid 2-[18F]FDG PET/MRI scan provides simultaneous information on structure and metabolism. Using this approach for the first time on HDGECs, we highlight the importance of partial volume effect correction in order not to underestimate the standardized uptake value and thereby the risk of overestimating the metabolic effect on the striatal structures, which potentially could bias studies determining imaging outcome measures of interventions in HDGECs and probably also symptomatic HD.

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Improved longitudinal [18F]-AV45 amyloid PET by white matter reference and VOI-based partial volume effect correction

NeuroImage ◽

10.1016/j.neuroimage.2014.11.055 ◽

2015 ◽

Vol 108 ◽

pp. 450-459 ◽

Cited By ~ 69

Author(s):

Matthias Brendel ◽

Marcus Högenauer ◽

Andreas Delker ◽

Julia Sauerbeck ◽

Peter Bartenstein ◽

...

Keyword(s):

White Matter ◽

Volume Effect ◽

Partial Volume Effect ◽

Amyloid Pet ◽

Partial Volume ◽

Partial Volume Effect Correction

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Quantitation of Regional Cerebral Blood Flow Corrected for Partial Volume Effect Using O-15 Water and PET: I. Theory, Error Analysis, and Stereologic Comparison

Journal of Cerebral Blood Flow & Metabolism ◽

10.1097/00004647-200008000-00009 ◽

2000 ◽

Vol 20 (8) ◽

pp. 1237-1251 ◽

Cited By ~ 56

Author(s):

Hidehiro Iida ◽

Ian Law ◽

Bente Pakkenberg ◽

Anders Krarup-Hansen ◽

Stefan Eberl ◽

...

Keyword(s):

Blood Flow ◽

White Matter ◽

Gray Matter ◽

Regional Cerebral Blood Flow ◽

Volume Effect ◽

Partial Volume Effect ◽

Regional Cerebral Blood ◽

Partial Volume ◽

Cortical Gray Matter ◽

Stereologic Analysis

Limited spatial resolution of positron emission tomography (PET) can cause significant underestimation in the observed regional radioactivity concentration (so-called partial volume effect or PVE) resulting in systematic errors in estimating quantitative physiologic parameters. The authors have formulated four mathematical models that describe the dynamic behavior of a freely diffusible tracer (H215O) in a region of interest (ROI) incorporating estimates of regional tissue flow that are independent of PVE. The current study was intended to evaluate the feasibility of these models and to establish a methodology to accurately quantify regional cerebral blood flow (CBF) corrected for PVE in cortical gray matter regions. Five monkeys were studied with PET after IV H215O two times (n = 3) or three times (n = 2) in a row. Two ROIs were drawn on structural magnetic resonance imaging (MRI) scans and projected onto the PET images in which regional CBF values and the water perfusable tissue fraction for the cortical gray matter tissue (hence the volume of gray matter) were estimated. After the PET study, the animals were killed and stereologic analysis was performed to assess the gray matter mass in the corresponding ROIs. Reproducibility of the estimated parameters and sensitivity to various error sources were also evaluated. All models tested in the current study yielded PVE-corrected regional CBF values (approximately 0.8 mL · min−1 · g−1 for models with a term for gray matter tissue and 0.5 mL · min−1 · g−1 for models with a term for a mixture of gray matter and white matter tissues). These values were greater than those obtained from ROIs tracing the gray matter cortex using conventional H215O autoradiography (approximately 0.40 mL · min−1 · g−1). Among the four models, configurations that included two parallel tissue compartments demonstrated better results with regards to the agreement of tissue time-activity curve and the Akaike's Information Criteria. Error sensitivity analysis suggested the model that fits three parameters of the gray matter CBF, the gray matter fraction, and the white matter fraction with fixed white matter CBF as the most reliable and suitable for estimating the gray matter CBF. Reproducibility with this model was 11% for estimating the gray matter CBF. The volume of gray matter tissue can also be estimated using this model and was significantly correlated with the results from the stereologic analysis. However, values were significantly smaller compared with those measured by stereologic analysis by 40%, which can not be explained by the methodologic errors. In conclusion, the partial volume correction was essential in quantitation of regional CBF. The method presented in this article provided the PVE-corrected regional CBF in the cortical gray matter tissue. This study also suggests that further studies are required before using MRI derived anatomic information for PVE correction in PET.

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