TY - JOUR
T1 - Improving the spatial alignment in PET/CT using amplitude-based respiration-gated PET and patient-specific breathing-instructed CT
AU - van der Vos, Charlotte S.
AU - Meeuwis, Antoi P.W.
AU - Grootjans, Willem
AU - de Geus-Oei, Lioe Fee
AU - Visser, Eric P.
PY - 2019/6/1
Y1 - 2019/6/1
N2 - Appropriate attenuation correction is important for accurate quantification of SUVs in PET. Patient respiratory motion can introduce a spatial mismatch between respiration-gated PET and CT, reducing quantitative accuracy. In this study, the effect of a patient-specific breathing-instructed CT protocol on the spatial alignment between CT and amplitude-based optimal respiration-gated PET images was investigated. Methods: 18F-FDG PET/CT imaging was performed on 20 patients. In addition to the standard low-dose free-breathing CT, breathhold CT was performed. The amplitude limits of the respiration-gated PET were used to instruct patients to hold their breath during CT acquisition at a similar amplitude level. Spatial mismatch was quantified using the position differences between the lung-liver transition in PET and CT images, the distance between PET and CT lesions' centroids, and the amount of overlap as indicated by the Jaccard similarity coefficient. Furthermore, the effect on attenuation correction was quantified by measuring SUVs, metabolic tumor volume, and total lesion glycolysis (TLG) of lung lesions. Results: All patients found the breathing instructions feasible; however, 4 patients had trouble complying with the instructions. In total, 18 patients were included. The average distance between the lung-liver transition between PET and CT was significantly reduced for breath-hold CT (1.7 ± 2.1 mm), compared with standard CT (5.6 ± 7.3 mm) (P = 0.049). Furthermore, the mean distance between the lesions' centroids on PET and CT was significantly smaller for breath-hold CT (3.6 ± 2.0 mm) than for standard CT (5.5 ± 6.5 mm) (P = 0.040). Quantification of lung lesion SUV was significantly affected, with a higher SUVmean when breath-hold CT (6.3 ± 3.9 g/cm3) was used for image reconstruction than for standard CT (6.1 ± 3.8 g/cm3) (P = 0.044). Though metabolic tumor volume was not significantly different, TLG reached statistical significance. Conclusion: Optimal respiration-gated PET in combination with patient-specific breathing-instructed CT results in an improved alignment between PET and CT images and shows an increased SUVmean and TLG. Even though the effects are small, a more accurate SUV and TLG determination is of importance for a more stable PET quantification, which is relevant for radiotherapy planning and therapy response monitoring.
AB - Appropriate attenuation correction is important for accurate quantification of SUVs in PET. Patient respiratory motion can introduce a spatial mismatch between respiration-gated PET and CT, reducing quantitative accuracy. In this study, the effect of a patient-specific breathing-instructed CT protocol on the spatial alignment between CT and amplitude-based optimal respiration-gated PET images was investigated. Methods: 18F-FDG PET/CT imaging was performed on 20 patients. In addition to the standard low-dose free-breathing CT, breathhold CT was performed. The amplitude limits of the respiration-gated PET were used to instruct patients to hold their breath during CT acquisition at a similar amplitude level. Spatial mismatch was quantified using the position differences between the lung-liver transition in PET and CT images, the distance between PET and CT lesions' centroids, and the amount of overlap as indicated by the Jaccard similarity coefficient. Furthermore, the effect on attenuation correction was quantified by measuring SUVs, metabolic tumor volume, and total lesion glycolysis (TLG) of lung lesions. Results: All patients found the breathing instructions feasible; however, 4 patients had trouble complying with the instructions. In total, 18 patients were included. The average distance between the lung-liver transition between PET and CT was significantly reduced for breath-hold CT (1.7 ± 2.1 mm), compared with standard CT (5.6 ± 7.3 mm) (P = 0.049). Furthermore, the mean distance between the lesions' centroids on PET and CT was significantly smaller for breath-hold CT (3.6 ± 2.0 mm) than for standard CT (5.5 ± 6.5 mm) (P = 0.040). Quantification of lung lesion SUV was significantly affected, with a higher SUVmean when breath-hold CT (6.3 ± 3.9 g/cm3) was used for image reconstruction than for standard CT (6.1 ± 3.8 g/cm3) (P = 0.044). Though metabolic tumor volume was not significantly different, TLG reached statistical significance. Conclusion: Optimal respiration-gated PET in combination with patient-specific breathing-instructed CT results in an improved alignment between PET and CT images and shows an increased SUVmean and TLG. Even though the effects are small, a more accurate SUV and TLG determination is of importance for a more stable PET quantification, which is relevant for radiotherapy planning and therapy response monitoring.
KW - Amplitude-based optimal respiratory gating
KW - Breathhold CT
KW - Image quantification in PET
KW - Lung tumors
KW - Spatial alignment
UR - http://www.scopus.com/inward/record.url?scp=85067039688&partnerID=8YFLogxK
U2 - 10.2967/jnmt.118.215970
DO - 10.2967/jnmt.118.215970
M3 - Article
C2 - 30413602
AN - SCOPUS:85067039688
SN - 0091-4916
VL - 47
SP - 154
EP - 159
JO - Journal of nuclear medicine technology
JF - Journal of nuclear medicine technology
IS - 2
ER -