Limits...
Comparing approaches to correct for respiratory motion in NH3 PET-CT cardiac perfusion imaging.

Schleyer PJ, O'Doherty MJ, Barrington SF, Morton G, Marsden PK - Nucl Med Commun (2013)

Bottom Line: However, cases were found where alignment worsened and severe artefacts resulted.This occurred in more cases and to a greater extent for the averaged and gated CT, where the anterior wall intensity reduced by more than 10% in 21 and 24 cases, respectively, compared with six cases for the pseudo-gated CT.The pseudo-gated CT was found to be the most robust method.

View Article: PubMed Central - PubMed

Affiliation: Division of Imaging Sciences and Biomedical Engineering, King's College London, King's Health Partners, St. Thomas' Hospital, London, UK.

ABSTRACT

Aim: Respiratory motion affects cardiac PET-computed tomography (CT) imaging by reducing attenuation correction (AC) accuracy and by introducing blur. The aim of this study was to compare three approaches for reducing motion-induced AC errors and evaluate the inclusion of respiratory motion correction.

Materials and methods: AC with a helical CT was compared with averaged cine and gated cine CT, as well as with a pseudo-gated CT, which was produced by applying PET-derived motion fields to the helical CT. Data-driven gating was used to produce respiratory-gated PET and CT images, and 60 NH3 PET scans were attenuation corrected with each of the CTs. Respiratory motion correction was applied to the gated and pseudo-gated attenuation-corrected PET images.

Results: Anterior and lateral wall intensity measured in attenuation-corrected PET images generally increased when PET-CT alignment improved and decreased when alignment degraded. On average, all methods improved PET-CT liver and cardiac alignment, and increased anterior wall intensity by more than 10% in 36, 33 and 25 cases for the averaged, gated and pseudo-gated CTAC PET images, respectively. However, cases were found where alignment worsened and severe artefacts resulted. This occurred in more cases and to a greater extent for the averaged and gated CT, where the anterior wall intensity reduced by more than 10% in 21 and 24 cases, respectively, compared with six cases for the pseudo-gated CT. Application of respiratory motion correction increased the average anterior and inferior wall intensity, but only 13% of cases increased by more than 10%.

Conclusion: All methods improved average respiratory-induced AC errors; however, some severe artefacts were produced. The pseudo-gated CT was found to be the most robust method.

Show MeSH

Related in: MedlinePlus

PET-CT alignment of the liver. A profile was defined along the z-axis over the liver edge in both data sets, and a straight line was fitted to the section ranging from 0.8 to 0.2 of the intensity normalized profile. Alignment was defined as the z-axis separation between the two straight lines at y=0.5. CT, computed tomography; NAC, non-attenuation-corrected; VOI, volume of interest.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3815144&req=5

Figure 1: PET-CT alignment of the liver. A profile was defined along the z-axis over the liver edge in both data sets, and a straight line was fitted to the section ranging from 0.8 to 0.2 of the intensity normalized profile. Alignment was defined as the z-axis separation between the two straight lines at y=0.5. CT, computed tomography; NAC, non-attenuation-corrected; VOI, volume of interest.

Mentions: A straight line was fitted to the central segment of the profile, which spanned 20–80% of the profile range. The point where the fitted line intercepted 50% of the profile range defined the approximate location of the organ edge along the z-axis. Figure 1 illustrates the liver edge definition for PET and CTAC slices from the same patient. The displacement between the liver positions in PET and CTAC is highlighted.


Comparing approaches to correct for respiratory motion in NH3 PET-CT cardiac perfusion imaging.

Schleyer PJ, O'Doherty MJ, Barrington SF, Morton G, Marsden PK - Nucl Med Commun (2013)

PET-CT alignment of the liver. A profile was defined along the z-axis over the liver edge in both data sets, and a straight line was fitted to the section ranging from 0.8 to 0.2 of the intensity normalized profile. Alignment was defined as the z-axis separation between the two straight lines at y=0.5. CT, computed tomography; NAC, non-attenuation-corrected; VOI, volume of interest.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3815144&req=5

Figure 1: PET-CT alignment of the liver. A profile was defined along the z-axis over the liver edge in both data sets, and a straight line was fitted to the section ranging from 0.8 to 0.2 of the intensity normalized profile. Alignment was defined as the z-axis separation between the two straight lines at y=0.5. CT, computed tomography; NAC, non-attenuation-corrected; VOI, volume of interest.
Mentions: A straight line was fitted to the central segment of the profile, which spanned 20–80% of the profile range. The point where the fitted line intercepted 50% of the profile range defined the approximate location of the organ edge along the z-axis. Figure 1 illustrates the liver edge definition for PET and CTAC slices from the same patient. The displacement between the liver positions in PET and CTAC is highlighted.

Bottom Line: However, cases were found where alignment worsened and severe artefacts resulted.This occurred in more cases and to a greater extent for the averaged and gated CT, where the anterior wall intensity reduced by more than 10% in 21 and 24 cases, respectively, compared with six cases for the pseudo-gated CT.The pseudo-gated CT was found to be the most robust method.

View Article: PubMed Central - PubMed

Affiliation: Division of Imaging Sciences and Biomedical Engineering, King's College London, King's Health Partners, St. Thomas' Hospital, London, UK.

ABSTRACT

Aim: Respiratory motion affects cardiac PET-computed tomography (CT) imaging by reducing attenuation correction (AC) accuracy and by introducing blur. The aim of this study was to compare three approaches for reducing motion-induced AC errors and evaluate the inclusion of respiratory motion correction.

Materials and methods: AC with a helical CT was compared with averaged cine and gated cine CT, as well as with a pseudo-gated CT, which was produced by applying PET-derived motion fields to the helical CT. Data-driven gating was used to produce respiratory-gated PET and CT images, and 60 NH3 PET scans were attenuation corrected with each of the CTs. Respiratory motion correction was applied to the gated and pseudo-gated attenuation-corrected PET images.

Results: Anterior and lateral wall intensity measured in attenuation-corrected PET images generally increased when PET-CT alignment improved and decreased when alignment degraded. On average, all methods improved PET-CT liver and cardiac alignment, and increased anterior wall intensity by more than 10% in 36, 33 and 25 cases for the averaged, gated and pseudo-gated CTAC PET images, respectively. However, cases were found where alignment worsened and severe artefacts resulted. This occurred in more cases and to a greater extent for the averaged and gated CT, where the anterior wall intensity reduced by more than 10% in 21 and 24 cases, respectively, compared with six cases for the pseudo-gated CT. Application of respiratory motion correction increased the average anterior and inferior wall intensity, but only 13% of cases increased by more than 10%.

Conclusion: All methods improved average respiratory-induced AC errors; however, some severe artefacts were produced. The pseudo-gated CT was found to be the most robust method.

Show MeSH
Related in: MedlinePlus