Image quality parameters for different PET acquisition times arranged for subgroups.

Image quality parameters for different PET acquisition times arranged for subgroups.</p

Boxplots of image quality parameter against PET acquisition time.

Boxplots of the image quality score (IQS), which is defined as nondiagnostic = 0, poor = 1, moderate = 2 and good = 3; the image noise (blood pool), the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) against PET acquisition time in minutes per bed (mpb). Note that the image quality slightly but progressively decreases in each boxplot towards lower PET acquisition times. Also the SNR and CNR decrease with lower acquisition times, while the image noise increases.</p

Image quality parameters in different body regions.

Overview over the average standard-uptake-values (SUVs) SUVmean, SUVmax and the signal-to-noise ratio (SNR) for four different body regions (head/neck, thorax, abdomen, pelvis/upper legs). The relative difference in % is given for 3, 2 and 1 min per bed (mpb) PET acquisition time in comparison to 4 mpb serving as the reference standard. The impact of reduced PET acquisition times on image quality and quantification parameters is lower for the thorax and pelvic body regions.</p

Correlation coefficients between image quality determinants and PET image quality parameters.

Correlation coefficients between image quality determinants and PET image quality parameters.</p

Quantitative and qualitative image analysis for different PET acquisition times.

Quantitative and qualitative image analysis for different PET acquisition times.</p

Patient example of consistently good image quality for different PET acquisition times.

Example of consistently good image quality. MR images, PET/MR fusion images and PET images of patient #10 after 4, 3, 2 and 1 minutes per bed (mpb) position in coronal and axial orientation. The lesion is marked (red arrow). In addition an axial slice of the liver is shown. Discrete stripe artifacts in MR images result from coronal reformats at the positions where the transaxially acquired slice stack of two neighbored bed positions in the thorax are merged. Image noise (blood pool) increases from 18.7% at the 4 mpb to 23.7% in 1 mpb reconstruction. The CNR decreases from 28.3 at 4 mpb to 19.9 at 1 mpb. The SNR decreases from 14.8 at 4 mpb to 10.0 at 1 mpb.</p

Correlation of two image quality parameters against BMI for different PET acquisition times.

Correlation graphs of two image quality parameters. The image noise in the blood pool and the signal-to-noise ratio (SNR) against the body-mass-index (BMI) of each patient is compared for 1, 2, 3 and 4 minutes per bed position PET acquisition. Note that image noise decreases with longer PET acquisition times, while SNR increases.</p

Patient example of decreasing image quality with shorter PET acquisition times.

Example of decreasing image quality. MR images, fusion images and PET images of patient #24 after 4, 3, 2 and 1 minutes per bed (mpb) position in coronal and axial orientation. In addition an axial slice of the liver is shown. The lesion is marked (red arrow). Note that the marked lymph node lesion is not well detectable in PET images with 1 min timeframe. Discrete stripe artifacts in MR images result from coronal reformats at the positions where the transaxially acquired slice stack of two neighbored bed positions in the thorax are merged. Image noise (blood pool) increases from 28.1% at the 4 mpb to 58.1% in 1 mpb reconstruction. The CNR decreases from 21.1 at 4 mpb to 15.4 at 2 mpb. The SNR decreases from 6.6 at 4 mpb to 3.6 at 2 mpb.</p

Detailed patient information.

Detailed patient information.</p

MR sequence parameters.

MR sequence parameters.</p