TY - ABST

T1 - Repeated measurements of lower leg skeletal muscle perfusion using 15O-water PET/CT

AU - Christensen, Nana Louise

AU - Buhl, Christian Selmer

AU - Sørensen, Jens

AU - Bouchelouche, Kirsten

AU - Madsen, Michael Alle

AU - Tolbod, Lars Poulsen

PY - 2022

Y1 - 2022

N2 - Aim/Introduction: 15O-water PET/CT is the gold standard for noninvasive measurements of tissue blood fow and can potentiallyplay a future role in the diagnosis and treatment of peripheral arterydisease. In the current study, we aimed to measure the variation ofnormal resting blood fow in lower leg muscles between individuals(healthy subjects) as well as between repeated measurements inthe same individual. Materials and Methods: We have enrolled7/10 planned healthy subjects who underwent two identical15O-water PET/CT scans of the lower legs, separated by a 5-minutebreak. During the break, subjects were taken out of the scanner andasked to take a few steps. After additional 5 minutes of resting in asupine position, they completed the second scan. In both scans,a standardized intravenous injection of 400 MBq 15O-H2O wasfollowed by a 6-minute dynamic PET acquisition. In low-dose CTimages, we defned volumes of interest (VOIs) in diferent lower legmuscles (gastrocnemius(GAS), soleus(SOL), tibialis anterior(TA), andperoneus longus(PL)) of each subject. As the PET scan was acquiredimmediately after the CT, VOIs could be transferred directly to thePET images for quantitative measurements of 15O-H2O uptake,and time-activity curves were extracted. Kinetic analysis wasperformed using in-house developed software. K1 (ml/100ml/min)was estimated using a single-tissue compartment model. Results:Resting K1 values ranged from 0.16-0.73 ml/100ml/min (median0.26,IQR:0.21-0.33). At muscle level, variation was observed inthe muscle groups, with median K1 values of 0.32(GAS), 0.24(PL),0.37(SOL), and 0.25(TA) ml/100ml/min in the frst scan. Repeatedmeasurements of 15O-water PET/CT perfusion in lower extremitiesshowed a strong correlation of K1 values (slope:1.02,intercept:-0.03,r=0.90) and the blood input function did not change betweenthe repeated scans (correlation for AUC: r=0.97 with no signifcantbias). Bland-Altman analysis revealed both negative and positiveproportional bias at an individual level in 3/6 scans, suggesting thatperfusion changed between the scans. Conclusion: Normal restingblood fow in four muscle groups of the lower leg ranged from 0.16-0.73 ml/100ml/min in healthy individuals. The largest variation wasseen between individuals, whereas a smaller variation was seenbetween muscle groups. Repeated measurement of resting bloodfow yielded a strong overall correlation of K1. When utilizing restingblood fow of the lower extremities for vascular disease evaluation(e.g. diabetes) or treatment response evaluation, inter-patientvariation in blood fow, as well as intra-patient variation inducedby the small diferences in resting conditions, must be taken intoaccount

AB - Aim/Introduction: 15O-water PET/CT is the gold standard for noninvasive measurements of tissue blood fow and can potentiallyplay a future role in the diagnosis and treatment of peripheral arterydisease. In the current study, we aimed to measure the variation ofnormal resting blood fow in lower leg muscles between individuals(healthy subjects) as well as between repeated measurements inthe same individual. Materials and Methods: We have enrolled7/10 planned healthy subjects who underwent two identical15O-water PET/CT scans of the lower legs, separated by a 5-minutebreak. During the break, subjects were taken out of the scanner andasked to take a few steps. After additional 5 minutes of resting in asupine position, they completed the second scan. In both scans,a standardized intravenous injection of 400 MBq 15O-H2O wasfollowed by a 6-minute dynamic PET acquisition. In low-dose CTimages, we defned volumes of interest (VOIs) in diferent lower legmuscles (gastrocnemius(GAS), soleus(SOL), tibialis anterior(TA), andperoneus longus(PL)) of each subject. As the PET scan was acquiredimmediately after the CT, VOIs could be transferred directly to thePET images for quantitative measurements of 15O-H2O uptake,and time-activity curves were extracted. Kinetic analysis wasperformed using in-house developed software. K1 (ml/100ml/min)was estimated using a single-tissue compartment model. Results:Resting K1 values ranged from 0.16-0.73 ml/100ml/min (median0.26,IQR:0.21-0.33). At muscle level, variation was observed inthe muscle groups, with median K1 values of 0.32(GAS), 0.24(PL),0.37(SOL), and 0.25(TA) ml/100ml/min in the frst scan. Repeatedmeasurements of 15O-water PET/CT perfusion in lower extremitiesshowed a strong correlation of K1 values (slope:1.02,intercept:-0.03,r=0.90) and the blood input function did not change betweenthe repeated scans (correlation for AUC: r=0.97 with no signifcantbias). Bland-Altman analysis revealed both negative and positiveproportional bias at an individual level in 3/6 scans, suggesting thatperfusion changed between the scans. Conclusion: Normal restingblood fow in four muscle groups of the lower leg ranged from 0.16-0.73 ml/100ml/min in healthy individuals. The largest variation wasseen between individuals, whereas a smaller variation was seenbetween muscle groups. Repeated measurement of resting bloodfow yielded a strong overall correlation of K1. When utilizing restingblood fow of the lower extremities for vascular disease evaluation(e.g. diabetes) or treatment response evaluation, inter-patientvariation in blood fow, as well as intra-patient variation inducedby the small diferences in resting conditions, must be taken intoaccount

KW - Contrast Media

KW - Humans

KW - Hypersensitivity

KW - Iodine

KW - Nuclear Medicine

KW - Radionuclide Imaging

U2 - 10.1007/s00259-022-05924-4

DO - 10.1007/s00259-022-05924-4

M3 - Conference abstract for conference

C2 - 34585268

SP - S271

T2 - Annual Congress of the European Association of Nuclear Medicine 2022

Y2 - 15 October 2022 through 19 December 2022

ER -