PURPOSE: Hybrid positron emission tomography and magnetic resonance (PET/MR) imaging performs a two-point Dixon MR sequence for attenuation correction. However, MR data in hybrid PET/MR should provide anatomic and morphologic information as well as an attenuation map. We evaluated the Dixon sequence of hybrid PET/MR for anatomic correlation of PET-positive lesions compared with contrast-enhanced PET/computed tomography (CT) in patients with oncologic diseases. METHODS: Twelve patients underwent a single injection, dual imaging protocol. PET/CT was performed with an intravenous contrast agent (85 ± 13 min after (18)F-FDG injection of 403 ± 45 MBq) and then (125 ± 19 min after injection) PET/MR was performed. Attenuation correction and anatomic allocation of PET were performed using contrast-enhanced CT for PET/CT and Dixon MR sequence for hybrid PET/MR. The Dixon MR sequence and contrast-enhanced CT were compared for anatomic correlation of PET-positive lesions (scoring scale ranging from 0 to 3 for visual ratings). Additionally, standardized uptake values (SUVs) for the detected lesions were assessed for quantitative comparison. RESULTS: Both hybrid PET/MR and contrast-enhanced PET/CT identified 55 lesions with increased FDG uptake in ten patients. In total, 28 lymph nodes, 11 bone lesions, 3 dermal nodules, 3 pleural thickening lesions, 2 thyroid nodules, 1 pancreas, 1 liver, 1 ovary, 1 uterus, 1 breast, 1 soft tissue and 2 lung lesions were present. The best performance was observed for anatomic correlation of PET findings by the contrast-enhanced CT scans (contrast-enhanced CT, 2.64 ± 0.70; in-phase, 1.29 ± 1.01; opposed-phase, 1.29 ± 1.15; water-weighted, 1.71 ± 1.07; fat weighted, 0.56 ± 1.03). A significant difference was observed between the scores obtained from the contrast-enhanced CT and all four coregistered Dixon MR images. Quantitative evaluation revealed a high correlation between the SUVs measured with hybrid PET/MR (SUVmean, 2.63 ± 1.62; SUVmax, 4.30 ± 2.88) and contrast-enhanced PET/CT (SUVmean, 3.88 ± 2.30; SUVmax, 6.53 ± 4.04) in PET-positive lesions (SUVmean, ρ = 0.93; SUVmax, ρ = 0.95), although hybrid PET/MR presented a decrease of SUVs compared with contrast-enhanced PET/CT (mean reduction; SUVmean, 32.44 ± 15.64 %; SUVmax, 35.16 ± 12.59 %). CONCLUSIONS: Despite different attenuation correction approaches, the SUV of PET-positive lesions correlated well between hybrid PET/MR and contrast-enhanced PET/CT. However Dixon MR images acquired for attenuation correction were insufficient to provide anatomic information of PET images because of low spatial resolution. Thus, additional MR sequence with fast and higher resolution may be necessary for anatomic information.
PURPOSE: Hybrid positron emission tomography and magnetic resonance (PET/MR) imaging performs a two-point Dixon MR sequence for attenuation correction. However, MR data in hybrid PET/MR should provide anatomic and morphologic information as well as an attenuation map. We evaluated the Dixon sequence of hybrid PET/MR for anatomic correlation of PET-positive lesions compared with contrast-enhanced PET/computed tomography (CT) in patients with oncologic diseases. METHODS: Twelve patients underwent a single injection, dual imaging protocol. PET/CT was performed with an intravenous contrast agent (85 ± 13 min after (18)F-FDG injection of 403 ± 45 MBq) and then (125 ± 19 min after injection) PET/MR was performed. Attenuation correction and anatomic allocation of PET were performed using contrast-enhanced CT for PET/CT and Dixon MR sequence for hybrid PET/MR. The Dixon MR sequence and contrast-enhanced CT were compared for anatomic correlation of PET-positive lesions (scoring scale ranging from 0 to 3 for visual ratings). Additionally, standardized uptake values (SUVs) for the detected lesions were assessed for quantitative comparison. RESULTS: Both hybrid PET/MR and contrast-enhanced PET/CT identified 55 lesions with increased FDG uptake in ten patients. In total, 28 lymph nodes, 11 bone lesions, 3 dermal nodules, 3 pleural thickening lesions, 2 thyroid nodules, 1 pancreas, 1 liver, 1 ovary, 1 uterus, 1 breast, 1 soft tissue and 2 lung lesions were present. The best performance was observed for anatomic correlation of PET findings by the contrast-enhanced CT scans (contrast-enhanced CT, 2.64 ± 0.70; in-phase, 1.29 ± 1.01; opposed-phase, 1.29 ± 1.15; water-weighted, 1.71 ± 1.07; fat weighted, 0.56 ± 1.03). A significant difference was observed between the scores obtained from the contrast-enhanced CT and all four coregistered Dixon MR images. Quantitative evaluation revealed a high correlation between the SUVs measured with hybrid PET/MR (SUVmean, 2.63 ± 1.62; SUVmax, 4.30 ± 2.88) and contrast-enhanced PET/CT (SUVmean, 3.88 ± 2.30; SUVmax, 6.53 ± 4.04) in PET-positive lesions (SUVmean, ρ = 0.93; SUVmax, ρ = 0.95), although hybrid PET/MR presented a decrease of SUVs compared with contrast-enhanced PET/CT (mean reduction; SUVmean, 32.44 ± 15.64 %; SUVmax, 35.16 ± 12.59 %). CONCLUSIONS: Despite different attenuation correction approaches, the SUV of PET-positive lesions correlated well between hybrid PET/MR and contrast-enhanced PET/CT. However Dixon MR images acquired for attenuation correction were insufficient to provide anatomic information of PET images because of low spatial resolution. Thus, additional MR sequence with fast and higher resolution may be necessary for anatomic information.
Entities:
Keywords:
Fluorodeoxyglucose F-18; Magnetic resonance imaging; Neoplasms; Positron emission tomography; Positron emission tomography and computed tomography
Authors: Marco Wiesmüller; Harald H Quick; Bharath Navalpakkam; Michael M Lell; Michael Uder; Philipp Ritt; Daniela Schmidt; Michael Beck; Torsten Kuwert; Carl C von Gall Journal: Eur J Nucl Med Mol Imaging Date: 2012-10-06 Impact factor: 9.236
Authors: Gaspar Delso; Sebastian Fürst; Björn Jakoby; Ralf Ladebeck; Carl Ganter; Stephan G Nekolla; Markus Schwaiger; Sibylle I Ziegler Journal: J Nucl Med Date: 2011-11-11 Impact factor: 10.057
Authors: Philipp Heusch; Christian Buchbender; Karsten Beiderwellen; Felix Nensa; Verena Hartung-Knemeyer; Thomas C Lauenstein; Andreas Bockisch; Michael Forsting; Gerald Antoch; Till A Heusner Journal: Eur J Radiol Date: 2013-02-08 Impact factor: 3.528
Authors: Benedikt Schaarschmidt; Christian Buchbender; Benedikt Gomez; Christian Rubbert; Florian Hild; Jens Köhler; Johannes Grueneisen; Henning Reis; Verena Ruhlmann; Axel Wetter; Harald H Quick; Gerald Antoch; Philipp Heusch Journal: Eur J Nucl Med Mol Imaging Date: 2015-04-08 Impact factor: 9.236
Authors: Jorge D Oldan; Shetal N Shah; Richard C Brunken; Frank P DiFilippo; Nancy A Obuchowski; Michael A Bolen Journal: J Nucl Cardiol Date: 2015-06-13 Impact factor: 5.952
Authors: Laurent Dercle; Désirée Deandreis; Marie Terroir; Sophie Leboulleux; Jean Lumbroso; Martin Schlumberger Journal: Eur J Nucl Med Mol Imaging Date: 2016-06 Impact factor: 9.236
Authors: Amy N Melsaether; Roy A Raad; Akshat C Pujara; Fabio D Ponzo; Kristine M Pysarenko; Komal Jhaveri; James S Babb; Eric E Sigmund; Sungheon G Kim; Linda A Moy Journal: Radiology Date: 2016-03-29 Impact factor: 11.105
Authors: Akshat C Pujara; Roy A Raad; Fabio Ponzo; Carolyn Wassong; James S Babb; Linda Moy; Amy N Melsaether Journal: Breast J Date: 2016-02-04 Impact factor: 2.431
Authors: Miguel Ramalho; Mamdoh AlObaidy; Onofrio A Catalano; Alexander R Guimaraes; Marco Salvatore; Richard C Semelka Journal: Eur J Radiol Open Date: 2014-09-16