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Image-derived input function in dynamic human PET/CT: methodology and validation with 11C-acetate and 18F-fluorothioheptadecanoic acid in muscle and 18F-fluorodeoxyglucose in brain.

Croteau E, Lavallée E, Labbe SM, Hubert L, Pifferi F, Rousseau JA, Cunnane SC, Carpentier AC, Lecomte R, Bénard F - Eur. J. Nucl. Med. Mol. Imaging (2010)

Bottom Line: These IDIF data were then compared to actual AIFs from patients.A one-way repeated measures (ANOVA) and Tukey's test showed a statistically significant difference for the IDIF not corrected for RC (p<0.0001).Correctly obtained, carotid and femoral artery IDIFs can be used as a substitute for AIFs to perform tracer kinetic modelling in skeletal femoral muscles and brain analyses.

View Article: PubMed Central - PubMed

Affiliation: Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada.

ABSTRACT

Purpose: Despite current advances in PET/CT systems, blood sampling still remains the standard method to obtain the radiotracer input function for tracer kinetic modelling. The purpose of this study was to validate the use of image-derived input functions (IDIF) of the carotid and femoral arteries to measure the arterial input function (AIF) in PET imaging. The data were obtained from two different research studies, one using (18)F-FDG for brain imaging and the other using (11)C-acetate and (18)F-fluoro-6-thioheptadecanoic acid ((18)F-FTHA) in femoral muscles.

Methods: The method was validated with two phantom systems. First, a static phantom consisting of syringes of different diameters containing radioactivity was used to determine the recovery coefficient (RC) and spill-in factors. Second, a dynamic phantom built to model bolus injection and clearance of tracers was used to establish the correlation between blood sampling, AIF and IDIF. The RC was then applied to the femoral artery data from PET imaging studies with (11)C-acetate and (18)F-FTHA and to carotid artery data from brain imaging with (18)F-FDG. These IDIF data were then compared to actual AIFs from patients.

Results: With (11)C-acetate, the perfusion index in the femoral muscle was 0.34+/-0.18 min(-1) when estimated from the actual time-activity blood curve, 0.29+/-0.15 min(-1) when estimated from the corrected IDIF, and 0.66+/-0.41 min(-1) when the IDIF data were not corrected for RC. A one-way repeated measures (ANOVA) and Tukey's test showed a statistically significant difference for the IDIF not corrected for RC (p<0.0001). With (18)F-FTHA there was a strong correlation between Patlak slopes, the plasma to tissue transfer rate calculated using the true plasma radioactivity content and the corrected IDIF for the femoral muscles (vastus lateralis r=0.86, p=0.027; biceps femoris r=0.90, p=0.017). On the other hand, there was no correlation between the values derived using the AIF and those derived using the uncorrected IDIF. Finally, in the brain imaging study with (18)F-FDG, the cerebral metabolic rate of glucose (CMRglc) measured using the uncorrected IDIF was consistently overestimated. The CMRglc obtained using blood sampling was 13.1+/-3.9 mg/100 g per minute and 14.0+/-5.7 mg/100 g per minute using the corrected IDIF (r ( 2 )=0.90).

Conclusion: Correctly obtained, carotid and femoral artery IDIFs can be used as a substitute for AIFs to perform tracer kinetic modelling in skeletal femoral muscles and brain analyses.

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CMRglc from standard three-compartment model analyses of 18F-FDG dynamic brain imaging, using an ROI on the frontal lobe of the brain. a The K1 fit from the compartmental model was computed using three different input functions: plasma sampling (Plasma), IDIF without correction, and IDIF corrected for carotid artery PVE (IDIF cor). b CMRglc was computed using three different input functions: plasma sampling (Plasma), IDIF without correction, and IDIF corrected for carotid artery partial volume (IDIF cor). For each subject, the diameter of the carotid artery was obtained from the bolus PET/CT coregistration images by measuring artery size on the CT image. The data from each patient are identified by the same symbol across all conditions. c Correlation between CMRglc of the frontal brain region derived from plasma sampling and from IDIF corrected for PVE
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Fig6: CMRglc from standard three-compartment model analyses of 18F-FDG dynamic brain imaging, using an ROI on the frontal lobe of the brain. a The K1 fit from the compartmental model was computed using three different input functions: plasma sampling (Plasma), IDIF without correction, and IDIF corrected for carotid artery PVE (IDIF cor). b CMRglc was computed using three different input functions: plasma sampling (Plasma), IDIF without correction, and IDIF corrected for carotid artery partial volume (IDIF cor). For each subject, the diameter of the carotid artery was obtained from the bolus PET/CT coregistration images by measuring artery size on the CT image. The data from each patient are identified by the same symbol across all conditions. c Correlation between CMRglc of the frontal brain region derived from plasma sampling and from IDIF corrected for PVE

Mentions: In the 18F-FDG brain imaging study, a standard compartmental analysis was applied using the frontal brain region for the tissue, and the blood curve was obtained using blood samples, the uncorrected IDIF and the IDIF corrected for PVE (Fig. 6). For blood samples, IDIF without correction and the IDIF corrected for PVE the K1 values were 0.029±0.011 min−1, 0.076±0.014 min−1 and 0.039±0.007 min−1, respectively. The average CMRglc values for the frontal brain were obtained from each input function: blood samples 13.8±3.9 mg/100 g per minute, IDIF without correction 24.8±8.8 mg/100 g per minute and IDIF corrected for PVE 14.0±5.7 mg/100 g per minute. Thus, omitting the correction for PVE resulted in an overestimation of the CMRglc by a factor of approximately two. One-way ANOVA repeated measures and Tukey’s test showed significant differences for K1 and CMRglc only for the IDIF uncorrected for PVE (F(2,5)=48.37; p<0.0001) and (F(2,5)=36.42; p<0.0001).Fig. 6


Image-derived input function in dynamic human PET/CT: methodology and validation with 11C-acetate and 18F-fluorothioheptadecanoic acid in muscle and 18F-fluorodeoxyglucose in brain.

Croteau E, Lavallée E, Labbe SM, Hubert L, Pifferi F, Rousseau JA, Cunnane SC, Carpentier AC, Lecomte R, Bénard F - Eur. J. Nucl. Med. Mol. Imaging (2010)

CMRglc from standard three-compartment model analyses of 18F-FDG dynamic brain imaging, using an ROI on the frontal lobe of the brain. a The K1 fit from the compartmental model was computed using three different input functions: plasma sampling (Plasma), IDIF without correction, and IDIF corrected for carotid artery PVE (IDIF cor). b CMRglc was computed using three different input functions: plasma sampling (Plasma), IDIF without correction, and IDIF corrected for carotid artery partial volume (IDIF cor). For each subject, the diameter of the carotid artery was obtained from the bolus PET/CT coregistration images by measuring artery size on the CT image. The data from each patient are identified by the same symbol across all conditions. c Correlation between CMRglc of the frontal brain region derived from plasma sampling and from IDIF corrected for PVE
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2914861&req=5

Fig6: CMRglc from standard three-compartment model analyses of 18F-FDG dynamic brain imaging, using an ROI on the frontal lobe of the brain. a The K1 fit from the compartmental model was computed using three different input functions: plasma sampling (Plasma), IDIF without correction, and IDIF corrected for carotid artery PVE (IDIF cor). b CMRglc was computed using three different input functions: plasma sampling (Plasma), IDIF without correction, and IDIF corrected for carotid artery partial volume (IDIF cor). For each subject, the diameter of the carotid artery was obtained from the bolus PET/CT coregistration images by measuring artery size on the CT image. The data from each patient are identified by the same symbol across all conditions. c Correlation between CMRglc of the frontal brain region derived from plasma sampling and from IDIF corrected for PVE
Mentions: In the 18F-FDG brain imaging study, a standard compartmental analysis was applied using the frontal brain region for the tissue, and the blood curve was obtained using blood samples, the uncorrected IDIF and the IDIF corrected for PVE (Fig. 6). For blood samples, IDIF without correction and the IDIF corrected for PVE the K1 values were 0.029±0.011 min−1, 0.076±0.014 min−1 and 0.039±0.007 min−1, respectively. The average CMRglc values for the frontal brain were obtained from each input function: blood samples 13.8±3.9 mg/100 g per minute, IDIF without correction 24.8±8.8 mg/100 g per minute and IDIF corrected for PVE 14.0±5.7 mg/100 g per minute. Thus, omitting the correction for PVE resulted in an overestimation of the CMRglc by a factor of approximately two. One-way ANOVA repeated measures and Tukey’s test showed significant differences for K1 and CMRglc only for the IDIF uncorrected for PVE (F(2,5)=48.37; p<0.0001) and (F(2,5)=36.42; p<0.0001).Fig. 6

Bottom Line: These IDIF data were then compared to actual AIFs from patients.A one-way repeated measures (ANOVA) and Tukey's test showed a statistically significant difference for the IDIF not corrected for RC (p<0.0001).Correctly obtained, carotid and femoral artery IDIFs can be used as a substitute for AIFs to perform tracer kinetic modelling in skeletal femoral muscles and brain analyses.

View Article: PubMed Central - PubMed

Affiliation: Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada.

ABSTRACT

Purpose: Despite current advances in PET/CT systems, blood sampling still remains the standard method to obtain the radiotracer input function for tracer kinetic modelling. The purpose of this study was to validate the use of image-derived input functions (IDIF) of the carotid and femoral arteries to measure the arterial input function (AIF) in PET imaging. The data were obtained from two different research studies, one using (18)F-FDG for brain imaging and the other using (11)C-acetate and (18)F-fluoro-6-thioheptadecanoic acid ((18)F-FTHA) in femoral muscles.

Methods: The method was validated with two phantom systems. First, a static phantom consisting of syringes of different diameters containing radioactivity was used to determine the recovery coefficient (RC) and spill-in factors. Second, a dynamic phantom built to model bolus injection and clearance of tracers was used to establish the correlation between blood sampling, AIF and IDIF. The RC was then applied to the femoral artery data from PET imaging studies with (11)C-acetate and (18)F-FTHA and to carotid artery data from brain imaging with (18)F-FDG. These IDIF data were then compared to actual AIFs from patients.

Results: With (11)C-acetate, the perfusion index in the femoral muscle was 0.34+/-0.18 min(-1) when estimated from the actual time-activity blood curve, 0.29+/-0.15 min(-1) when estimated from the corrected IDIF, and 0.66+/-0.41 min(-1) when the IDIF data were not corrected for RC. A one-way repeated measures (ANOVA) and Tukey's test showed a statistically significant difference for the IDIF not corrected for RC (p<0.0001). With (18)F-FTHA there was a strong correlation between Patlak slopes, the plasma to tissue transfer rate calculated using the true plasma radioactivity content and the corrected IDIF for the femoral muscles (vastus lateralis r=0.86, p=0.027; biceps femoris r=0.90, p=0.017). On the other hand, there was no correlation between the values derived using the AIF and those derived using the uncorrected IDIF. Finally, in the brain imaging study with (18)F-FDG, the cerebral metabolic rate of glucose (CMRglc) measured using the uncorrected IDIF was consistently overestimated. The CMRglc obtained using blood sampling was 13.1+/-3.9 mg/100 g per minute and 14.0+/-5.7 mg/100 g per minute using the corrected IDIF (r ( 2 )=0.90).

Conclusion: Correctly obtained, carotid and femoral artery IDIFs can be used as a substitute for AIFs to perform tracer kinetic modelling in skeletal femoral muscles and brain analyses.

Show MeSH
Related in: MedlinePlus