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. 2015 Feb 15;5(3):293-304.
eCollection 2015.

Quantitative carotid PET/MR imaging: clinical evaluation of MR-Attenuation correction versus CT-Attenuation correction in (18)F-FDG PET/MR emission data and comparison to PET/CT

Jason Bini  1 , Philip M Robson  2 , Claudia Calcagno  2 , Mootaz Eldib  1 , Zahi A Fayad  3
Affiliations

Quantitative carotid PET/MR imaging: clinical evaluation of MR-Attenuation correction versus CT-Attenuation correction in (18)F-FDG PET/MR emission data and comparison to PET/CT

Jason Bini et al. Am J Nucl Med Mol Imaging. .

Abstract

Current PET/MR systems employ segmentation of MR images and subsequent assignment of empirical attenuation coefficients for quantitative PET reconstruction. In this study we examine the differences in the quantification of (18)F-FDG uptake in the carotid arteries between PET/MR and PET/CT scanners. Five comparisons were performed to asses differences in PET quantification: i) PET/MR MR-based AC (MRAC) versus PET/MR CTAC, ii) PET/MR MRAC versus PET/CT, iii) PET/MR MRAC with carotid coil versus PET/MR MRAC without coil, iv) PET/MR MRAC scan 2 versus PET/MR MRAC scan 1, and v) PET/MR CTAC versus PET/CT. Standardized uptakes values (SUV) mean and SUV maximum were calculated for six regions-of-interests: left and right carotid arteries, left and right lungs, spine and muscle. Pearson's Correlation and Bland-Altman plots were used to compare SUV mean and maximum within each ROI of each patient. PET/MR emission data reconstructed with MRAC versus PET/MR emission data reconstructed with CTAC had percent differences of SUV mean ranging from -2.0% (Absolute Difference, -0.02) to 7.4% (absolute difference, 0.06). Percent differences within the carotid arteries proved to correlate well with differences of SUV mean of 5.4% (Absolute Difference, 0.07) in the left carotid and 2.7% (Absolute Difference, 0.03) in the right carotid. Pearson's correlation and Bland-Altman of PET/MR with MRAC versus PET/MR with CTAC showed high correlation between SUV mean (R(2)=0.80, mean difference 0.03 ± 0.18 SUV, p=0.3382), demonstrating excellent correlation within ROIs analyzed. The results of this study support the use of (18)F-FDG PET/MR for quantitative measure of inflammation in the carotid arteries.

Keywords: PET/CT; PET/MR; attenuation correction; cardiovascular; carotid arteries.

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Figures

Figure 1
Figure 1
Diagram of PET acquisitions that were performed to qualitatively and quantitatively compare PET images from PET/MR and PET/CT acquisitions.
Figure 2
Figure 2
Example of four of the six regions-of-interest traced in the axial view of the atMR MR acquisition. Left and Right carotid, spine and back muscle (soft tissue) are visible in this axial slice. The left and right lung are outside the axial view displayed here but were traced along the outer contour in the axial view in a similar matter.
Figure 3
Figure 3
Demonstration co-registration accuracy (A-C) MR (D-F) CT (G-I) overlay of MR (color scale) and CT (grayscale).
Figure 4
Figure 4
Coronal comparisons of CT- and MR-based attenuation maps and their respective PET reconstructions on PET/CT and PET/MR.
Figure 5
Figure 5
Percent difference error map between CTAC and assigned MRAC attenuation coefficients (top) and percent difference error map showing regional differences in SUV between PET/MR emission data reconstructed with the respective MRAC and CTAC maps (bottom).
Figure 6
Figure 6
Pearson’s correlation plots for all ROIs in all patients. PET/MR MRAC versus PET/MR CTAC (A) PET/MR MRAC versus PET/CT (B) PET/MR MRAC with carotid coil versus PET/MR MRAC without coil (C) PET/MR MRAC scan 2 versus PET/MR MRAC scan 1 (D) PET/MR CTAC versus PET/CT (E).
Figure 7
Figure 7
Bland-Altman plots for all ROIs in all patients. PET/MR MRAC versus PET/MR CTAC (A) PET/MR MRAC versus PET/CT (B) PET/MR MRAC with carotid coil versus PET/MR MRAC without coil (C) PET/MR MRAC scan 2 versus PET/MR MRAC scan 1 (D) PET/MR CTAC versus PET/CT (E).
See this image and copyright information in PMC

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