Value of a Dixon-based MR/PET attenuation correction sequence for the localization and evaluation of PET-positive lesions

• Published in: European journal of nuclear medicine and molecular imaging Vol. 38; no. 9; pp. 1691 - 1701
• Main Authors: Eiber, Matthias, Martinez-Möller, Axel, Souvatzoglou, Michael, Holzapfel, Konstantin, Pickhard, Anja, Löffelbein, Dennys, Santi, Ivan, Rummeny, Ernst J., Ziegler, Sibylle, Schwaiger, Markus, Nekolla, Stephan G., Beer, Ambros J.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.09.2011; Springer Nature B.V
• Subjects: Adult; Aged; Biological Transport; Cancer; Cardiology; Female; Humans; Image Processing, Computer-Assisted - methods; Imaging; Magnetic Resonance Imaging - methods; Male; Medical diagnosis; Medicine; Medicine & Public Health; Middle Aged; Neoplasms - diagnostic imaging; Neoplasms - metabolism; Neoplasms - physiopathology; NMR; Nuclear magnetic resonance; Nuclear Medicine; Oncology; Original Articles; Orthopedics; Positron-Emission Tomography - methods; Prospective Studies; Radiology; Respiration; Tomography; Tomography, X-Ray Computed; MR/PET; Localization; Attenuation correction; Low-dose CT; Dixon-based VIBE T1-weighted MR sequence
• ISSN: 1619-7070; 1619-7089
• DOI: 10.1007/s00259-011-1842-9

Purpose In this study, the potential contribution of Dixon-based MR imaging with a rapid low-resolution breath-hold sequence, which is a technique used for MR-based attenuation correction (AC) for MR/positron emission tomography (PET), was evaluated for anatomical correlation of PET-positive lesions on a 3T clinical scanner compared to low-dose CT. This technique is also used in a recently installed fully integrated whole-body MR/PET system. Methods Thirty-five patients routinely scheduled for oncological staging underwent 18 F-fluorodeoxyglucose (FDG) PET/CT and a 2-point Dixon 3-D volumetric interpolated breath-hold examination (VIBE) T1-weighted MR sequence on the same day. Two PET data sets reconstructed using attenuation maps from low-dose CT (PET AC_CT ) or simulated MR-based segmentation (PET AC_MR ) were evaluated for focal PET-positive lesions. The certainty for the correlation with anatomical structures was judged in the low-dose CT and Dixon-based MRI on a 4-point scale (0–3). In addition, the standardized uptake values (SUVs) for PET AC_CT and PET AC_MR were compared. Results Statistically, no significant difference could be found concerning anatomical localization for all 81 PET-positive lesions in low-dose CT compared to Dixon-based MR (mean 2.51 ± 0.85 and 2.37 ± 0.87, respectively; p  = 0.1909). CT tended to be superior for small lymph nodes, bone metastases and pulmonary nodules, while Dixon-based MR proved advantageous for soft tissue pathologies like head/neck tumours and liver metastases. For the PET AC_CT - and PET AC_MR -based SUVs (mean 6.36 ± 4.47 and 6.31 ± 4.52, respectively) a nearly complete concordance with a highly significant correlation was found ( r  = 0.9975, p  < 0.0001). Conclusion Dixon-based MR imaging for MR AC allows for anatomical allocation of PET-positive lesions similar to low-dose CT in conventional PET/CT. Thus, this approach appears to be useful for future MR/PET for body regions not fully covered by diagnostic MRI due to potential time constraints.