Table 1.
PET acquisition parameters.
Fig 1.
Bland Altman analysis assessing inter-reader variability in blood pool, liver, and whole parotid gland.
Minimal inter-reader SUVmean variability is seen for blood pool (top), liver (middle), and whole parotid gland (bottom) for both wbPET/CT (left column) and wbPET/MR (right column). The calculated bias (red line) as well as the upper and lower limits of agreement (outer black lines) are demarcated on each plot. The bias and limits of agreement are listed in the top-center or bottom-center of each plot.
Fig 2.
Bland Altman analysis assessing inter-reader variability for 1-cm parotid regional regions of interest.
Greater bias and limits of agreement were seen for the 1-cm parotid circular ROIs in the inferior (top), mid (middle), or superior (bottom) parotid gland for both wbPET/CT (left column) or wbPET/MR (right column). The calculated bias (red line) as well as the upper and lower limits of agreement (outer black lines) are demarcated on each plot. The bias and limits of agreement are listed in the top-center or bottom-center of each plot.
Fig 3.
Example demonstrating variability for parotid region of interests (ROIs).
Sagittal maximum intensity projection from the PET/MR [18F]DCFPyL PSMA tracer acquisition with labeled parotid gland and liver ROIs. Spatial variability of calculated SUVmean for the 1-cm ROIs obtained from the superior (sup), middle (mid), and inferior (inf) right parotid gland is seen with values of 18.6, 22.4, and 21.0 g/mL respectively.
Fig 4.
Bland Altman analysis assessing inter-modality variability between PET/CT and PET/MR acquisitions.
A slight bias of decreased SUVmean for blood pool (top) and increased SUVmean for liver (middle) and parotid gland (bottom) was seen for wbPET/MR compared to wbPET/CT regardless of reader. The calculated bias (red line) as well as the upper and lower limits of agreement (outer black lines) are demarcated on each plot. The bias and limits of agreement are listed in the bottom-center.
Fig 5.
Box plots for SUVmean of the liver and whole parotid gland regions of interest (ROIs) from both PyL PET/CT and PET/MR demonstrates greater interquartile and min-max range for the parotid compared to liver for both readers, reader 1 (A) and reader 2 (B) respectively. Box defines median and 1st and 3rd quartiles. Whiskers are maximum and minimum. Diamond defines the mean value.
Table 2.
Reference organ inter-subject variability according to reader and modality.