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Standardized uptake values and attenuation correction in 18 F-sodium fluoride PET of the equine foot and fetlock.

Abstract: Maximal standardized uptake values (SUV ) are commonly used for the interpretation of PET studies. Limited information regarding the SUV of F-NaF PET in horses is currently available in the literature. The goals of this retrospective secondary analysis study were to provide reference values for F-NaF SUV in the equine distal extremity and assess the effect of attenuation correction. Nonattenuation corrected (NAC) and CT-based attenuation corrected (CTAC) SUV were obtained from 19 feet and 19 fetlocks. Twenty regions of interest (ROIs) were defined for the foot and 22 for the fetlock. Areas presenting abnormal uptake were excluded. The overall NAC and CTAC SUV were 3.6 +/- 1.5 (mean +/- sd) and 5.0 +/- 1.8 for the feet and 2.9 +/- 1.1 and 3.8 +/- 1.4 for the fetlocks, respectively. The 3 ROIs showing the highest attenuation correction were the navicular center (83.4%), navicular flexor surface (74.9%) and distal phalanx flexor surface (81.3%), whereas attenuation correction was only 5.2% at the dorsal aspect of the proximal phalanx. Significant SUV differences were observed between the different ROIs (P < 0.0001), with the toe (CTAC SUV 7.7 +/- 3.7), dorsal (7.5 +/- 1.9) and central (6.1 +/- 2.2) ROIs of the distal phalanx being significantly higher than those of the other areas. This study demonstrates that attenuation correction affects SUVmax in the equine distal extremity and should be performed if CT data are available. However, as the maximal attenuation correction results in less than doubling the signal intensity, nonattenuation corrected images likely remain relevant for subjective clinical interpretation.
Publication Date: 2022-07-24 PubMed ID: 35871486DOI: 10.1111/vru.13127Google Scholar: Lookup
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  • Journal Article

Summary

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The study investigates the use and impact of maximal standardized uptake values (SUV) in Positron Emission Tomography (PET) studies involving the use of radioactive fluorine (F-NaF) in horses. By comparing nonattenuation corrected (NAC) and CT-based attenuation corrected (CTAC) SUV, the study aims to provide reference values for F-NaF SUV in equine health and assess the impact of attenuation correction on the results.

Understanding Standardized Uptake Values (SUV)

  • The SUV is a measure used in PET studies to quantify the distribution of radioactive tracers in the body of a subject, in this case, a horse.
  • These studies involve injecting a small amount of a radioactive substance into the subject, then using a PET scanner to measure how much of that tracer is absorbed in different parts of the body.
  • The SUV is then calculated by dividing the amount of radioactivity in a region of interest (ROI) by the injected dose of the radiotracer, adjusted for the person’s body weight.

What is F-NaF PET?

  • F-NaF PET refers to the use of a specific radioactive tracer, F-NaF, in a PET scan.
  • F-NaF is a bone-seeking radiopharmaceutical, meaning it tends to accumulate in areas of high bone turnover. Therefore, it’s often used to assess health conditions affecting the bones, such as cancer or injury.

Attenuation Correction

  • Attenuation correction is a process used to correct the SUV values for the amount of radiation that is absorbed (or “attenuated”) by different tissues as it passes through the body.
  • This study compared nonattenuation corrected (NAC) SUV values, which do not undergo this correction process, with CT-based attenuation corrected (CTAC) SUV values.

Findings of the Study

  • The study found that CT-based attenuation correction does influence the SUVmax in the equine foot and fetlock. Mean SUV values were higher after attenuation correction for both horse feet and fetlocks.
  • In particular, the study noted the highest areas of attenuation correction were found in regions like the navicular center, the navicular flexor surface, and the distal phalanx flexor surface.
  • The regions that showed significant SUV differences were the toe, dorsal and central ROIs of the distal phalanx.
  • However, even though attenuation correction was found to affect the SUVmax values, the changes were not large enough to double the signal intensity. Hence, nonattenuation corrected images can still likely remain relevant for clinical interpretation.

Importance of The Study

  • The results of this study serve to establish reference ranges for F-NaF SUV in the equine foot and fetlock, to provide a standard for future assessments and analyses in equine health.
  • The study also emphasizes the importance of considering attenuation correction when interpreting PET images, as it can affect the SUV results.

Cite This Article

APA
Sannajust K, Spriet M, Anishchenko S, Beylin D. (2022). Standardized uptake values and attenuation correction in 18 F-sodium fluoride PET of the equine foot and fetlock. Vet Radiol Ultrasound, 63(6), 771-778. https://doi.org/10.1111/vru.13127

Publication

ISSN: 1740-8261
NlmUniqueID: 9209635
Country: England
Language: English
Volume: 63
Issue: 6
Pages: 771-778

Researcher Affiliations

Sannajust, Kimberley
  • School of Veterinary Medicine, University of California Davis, Davis, California, USA.
Spriet, Mathieu
  • School of Veterinary Medicine, University of California Davis, Davis, California, USA.
Anishchenko, Sergey
  • LONGMILE Veterinary Imaging, Brain Biosciences Inc., Rockville, Maryland, USA.
Beylin, David
  • LONGMILE Veterinary Imaging, Brain Biosciences Inc., Rockville, Maryland, USA.

MeSH Terms

  • Animals
  • Horses
  • Sodium Fluoride
  • Retrospective Studies
  • Joints
  • Positron-Emission Tomography / veterinary
  • Positron-Emission Tomography / methods
  • Extremities

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Citations

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