Is There a Role for PET/MR?
This issue highlights the emergence of PET/MR, which follows the introduction of SPECT/CT and PET/CT that have convincingly shown that multimodality imaging can result in significantly improved disease characterization.
Merging PET and MRI imaging is attractive for several reasons. First, soft-tissue contrast provided by MRI is superior to that of CT which may allow for more accurate assessments of the brain, head and neck as well as the liver. Secondly, MRI can provide functional data and, in theory, is not limited to providing anatomical information. Thus, PET/MRI is especially attractive when molecular information from PET and MRI can be derived simultaneously. Finally, MRI does not involve ionizing radiation, which might be beneficial for imaging vulnerable populations.
However, several issues need to be resolved prior to widespread adoption of PET/MRI. First, the purchase price is high, ranging from $3 million to $5 million. The scanners, true combined or pseudo-hybrid systems, also are large, requiring a lot of installation space depending on the system configuration. Time is a factor as well, as PET/MR exams will take substantially longer than PET/CT to complete. Technical issues, such as correction for photon attenuation, have not been completely resolved. Another issue is cross disciplinary training of both physicians and technologists, as programs for both will be revised. Finally, it is unclear how PET/MRI procedures will be coded and billed, and what level of evidence that regulatory agencies will require to permit its widespread use. Demonstration of diagnostic superiority no longer is deemed sufficient to achieve reimbursement for new imaging technologies. Data showing a bene-ficial impact on patient management and outcomes also are required.
This issue also introduces novel imaging probes developed to differentiate between progressive and non-progressive neurodegenerative diseases. Probes that target beta-amyloid might provide earlier and more accurate insights into neurodegenerative diseases. It is noteworthy that 18F FDG-PET is remarkably accurate to differentiate between these entirely different processes. The performance of the newly introduced probes will need to be measured against FDG-PET.
We also should remember that PET/CT imaging still is markedly underutilized in clinical practice. Two studies have shown that PET or PET/CT-based staging can reduce the number of futile surgeries by close to 50 percent. This also should serve as a reminder that outcome parameters are not limited to patient survival and include cost effectiveness and quality of life data. PET/MRI will have to demonstrate that a similar impact on patient outcomes can be achieved across many indications.
Merging PET and MRI imaging is attractive for several reasons. First, soft-tissue contrast provided by MRI is superior to that of CT which may allow for more accurate assessments of the brain, head and neck as well as the liver. Secondly, MRI can provide functional data and, in theory, is not limited to providing anatomical information. Thus, PET/MRI is especially attractive when molecular information from PET and MRI can be derived simultaneously. Finally, MRI does not involve ionizing radiation, which might be beneficial for imaging vulnerable populations.
However, several issues need to be resolved prior to widespread adoption of PET/MRI. First, the purchase price is high, ranging from $3 million to $5 million. The scanners, true combined or pseudo-hybrid systems, also are large, requiring a lot of installation space depending on the system configuration. Time is a factor as well, as PET/MR exams will take substantially longer than PET/CT to complete. Technical issues, such as correction for photon attenuation, have not been completely resolved. Another issue is cross disciplinary training of both physicians and technologists, as programs for both will be revised. Finally, it is unclear how PET/MRI procedures will be coded and billed, and what level of evidence that regulatory agencies will require to permit its widespread use. Demonstration of diagnostic superiority no longer is deemed sufficient to achieve reimbursement for new imaging technologies. Data showing a bene-ficial impact on patient management and outcomes also are required.
This issue also introduces novel imaging probes developed to differentiate between progressive and non-progressive neurodegenerative diseases. Probes that target beta-amyloid might provide earlier and more accurate insights into neurodegenerative diseases. It is noteworthy that 18F FDG-PET is remarkably accurate to differentiate between these entirely different processes. The performance of the newly introduced probes will need to be measured against FDG-PET.
We also should remember that PET/CT imaging still is markedly underutilized in clinical practice. Two studies have shown that PET or PET/CT-based staging can reduce the number of futile surgeries by close to 50 percent. This also should serve as a reminder that outcome parameters are not limited to patient survival and include cost effectiveness and quality of life data. PET/MRI will have to demonstrate that a similar impact on patient outcomes can be achieved across many indications.