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

Abstract

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.

Discrimination and anatomical mapping of PET-positive lesions: comparison of CT attenuation-corrected PET images with coregistered MR and CT images in the abdomen

“…In PET-positive liver lesions coregistered PET and unenhanced MR images outperformed unenhanced PET/CT. These results are in line with those of Eiber et al [17] who used Dixon-based MR sequences (volumetric interpolated breath-hold examination) in comparison with a 20-mAs low-dose CT scan for anatomical correlation and delineation of PET-positive findings. However, there are important differences between the studies:…”

“…One metastatic lesion in the right adrenal was better visualized on CT than on MR images 3. Due to the small number of patients in the study by Eiber et al [17], the number of organ-specific lesions was not high enough for statistical analysis comparing low-dose CT and Dixon-MRI. Our larger and prospective study was able to provide statistically significant information.…”

“…in head and neck cancer, and has therefore a major impact on patient management [16]. Full coverage of the PET field of view (FOV) with a fast and robust MR pulse sequence is therefore necessary in oncology patients to provide anatomical correlation similar to that achieved with a low-dose CT scan [17]. Furthermore, this survey MR pulse sequence should ideally also provide data for anatomical MRbased attenuation correction (AC) of PET data equivalent to that provided by CT.…”

Whole-body PET/MRI in oncology: current status and clinical applications

“…In fused PET and MRI imaging, the results of Dixonbased MR imaging, a water/fat separation technique used for MR-based attenuation correction for PET/MRI, were evaluated for anatomical correlation of PET-positive lesions on a 3 T clinical scanner compared to low-dose CT [94]. No significant difference was found in anatomical localization for all PET-positive lesions in low-dose CT compared to Dixon-based MR [94].…”

Life is not black and white, nor just Shades of Gray

“…Likewise, in a survey performed in 2014 among international SPECT/CT users, an overwhelming majority of respondents wanted to employ their SPECT/CT system as a SPECT system with attenuation correction and coarse anatomical localization rather than to implement closer integration of radiology-driven imaging perspectives [23]. Finally, one of the first clinical papers on PET/MR promoted the sufficiency of a Blow-signal^sequence, typically used for MR-based attenuation correction [24], synonymous to a lowdose CT scan, for the anatomical localization of the PET findings [25]. These are but a few examples of the disconnect between the diagnostic professions at the apogee of combined imaging, which coincides with the most deterring phase of interaction between the two professions (Table 1).…”