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Integrated whole body MR/PET: where are we?

Yoo HJ, Lee JS, Lee JM - Korean J Radiol (2015)

Bottom Line: This review provides an overview of the technical background of combined MR/PET systems, a discussion of the potential advantages and technical challenges of hybrid MR/PET instrumentation, as well as collection of possible solutions.Various early clinical applications of integrated MR/PET are also addressed.Finally, the workflow issues of integrated MR/PET, including maximizing diagnostic information while minimizing acquisition time are discussed.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Seoul National University Hospital, Seoul 110-744, Korea.

ABSTRACT
Whole body integrated magnetic resonance imaging (MR)/positron emission tomography (PET) imaging systems have recently become available for clinical use and are currently being used to explore whether the combined anatomic and functional capabilities of MR imaging and the metabolic information of PET provide new insight into disease phenotypes and biology, and provide a better assessment of oncologic diseases at a lower radiation dose than a CT. This review provides an overview of the technical background of combined MR/PET systems, a discussion of the potential advantages and technical challenges of hybrid MR/PET instrumentation, as well as collection of possible solutions. Various early clinical applications of integrated MR/PET are also addressed. Finally, the workflow issues of integrated MR/PET, including maximizing diagnostic information while minimizing acquisition time are discussed.

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53-year-old male with radiation-induced osteosarcoma in right ilium before (A-C) and after (D-F) chemotherapy.A. Axial, T2-weighted MR image showed heterogeneous, T2 hyperintense soft-tissue mass in right ilium. B. Axial, post-contrast, T1-weighted MR image showed soft-tissue enhancement (arrow) with central non-enhancement before chemotherapy. C. Axial PET-CT image demonstrated increased FDG uptake (SUVmax = 21.84) in corresponding lesion. D. Axial, T2-weighted MR image obtained after chemotherapy shows decrease in tumor size. E. Axial, post-contrast, T1-weighted MR image obtained after chemotherapy shows decrease in area of soft-tissue enhancement (arrow). F. Corresponding to fused FDG-MR/PET image obtained after chemotherapy and which showed no pathological FDG uptake (SUVmax = 2.23). FDG = fluorodeoxyglucose, MR/PET = magnetic resonance imaging/positron emission tomography, SUVmax = maximum standardized uptake value
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Figure 7: 53-year-old male with radiation-induced osteosarcoma in right ilium before (A-C) and after (D-F) chemotherapy.A. Axial, T2-weighted MR image showed heterogeneous, T2 hyperintense soft-tissue mass in right ilium. B. Axial, post-contrast, T1-weighted MR image showed soft-tissue enhancement (arrow) with central non-enhancement before chemotherapy. C. Axial PET-CT image demonstrated increased FDG uptake (SUVmax = 21.84) in corresponding lesion. D. Axial, T2-weighted MR image obtained after chemotherapy shows decrease in tumor size. E. Axial, post-contrast, T1-weighted MR image obtained after chemotherapy shows decrease in area of soft-tissue enhancement (arrow). F. Corresponding to fused FDG-MR/PET image obtained after chemotherapy and which showed no pathological FDG uptake (SUVmax = 2.23). FDG = fluorodeoxyglucose, MR/PET = magnetic resonance imaging/positron emission tomography, SUVmax = maximum standardized uptake value

Mentions: Moreover, MR/PET could provide the information regarding not only the treatment response but also the restaging for surgical resection after neoadjuvant treatment in a single session (Figs. 7, 8). Currently, there are only a few reports that assess the potential benefit of MR/PET in the treatment response evaluation. Platzek et al. (90) evaluated the feasibility of sequential MR/PET for the therapy response evaluation of malignant lymphoma in nine patients. They showed excellent interobserver agreement regarding the Ann Arbor stage (κ = 0.97) and good interobserver agreement regarding the image quality (κ = 0.41), thus suggesting that FDG-MR/PET is a reliable imaging method. Schuler et al. (71) reported a case of rhabdomyosarcoma for which MR/PET was used to guide neoadjuvant treatment. They were able to determine whether neoadjuvant chemotherapy was effective after the response evaluation made with MR/PET, and then could perform curable resection at the optimal time. This case demonstrates that MR/PET could be a valuable method for solving clinical problems. Based on these reports, MR/PET is expected to offer a great opportunity for tumor-response evaluation and treatment monitoring. However, both PET and DWI are weak in their ability to differentiate viable tumor from inflammation/granulation tissue after neoadjuvant treatment, although for different reasons. The simultaneous acquisition of PET and MR images may be complementary to each other. The addition of a functional component, such as perfusion MR, could help detect early responders in patients undergoing neoadjuvant therapy, giving meaningful information to determine whether a further chemotherapy cycle is needed. In addition, MR/PET can provide additional meaningful information regarding the decision-making process for clinicians, and which will be advantageous for patients who require neoadjuvant chemotherapy or radiation therapy.


Integrated whole body MR/PET: where are we?

Yoo HJ, Lee JS, Lee JM - Korean J Radiol (2015)

53-year-old male with radiation-induced osteosarcoma in right ilium before (A-C) and after (D-F) chemotherapy.A. Axial, T2-weighted MR image showed heterogeneous, T2 hyperintense soft-tissue mass in right ilium. B. Axial, post-contrast, T1-weighted MR image showed soft-tissue enhancement (arrow) with central non-enhancement before chemotherapy. C. Axial PET-CT image demonstrated increased FDG uptake (SUVmax = 21.84) in corresponding lesion. D. Axial, T2-weighted MR image obtained after chemotherapy shows decrease in tumor size. E. Axial, post-contrast, T1-weighted MR image obtained after chemotherapy shows decrease in area of soft-tissue enhancement (arrow). F. Corresponding to fused FDG-MR/PET image obtained after chemotherapy and which showed no pathological FDG uptake (SUVmax = 2.23). FDG = fluorodeoxyglucose, MR/PET = magnetic resonance imaging/positron emission tomography, SUVmax = maximum standardized uptake value
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4296276&req=5

Figure 7: 53-year-old male with radiation-induced osteosarcoma in right ilium before (A-C) and after (D-F) chemotherapy.A. Axial, T2-weighted MR image showed heterogeneous, T2 hyperintense soft-tissue mass in right ilium. B. Axial, post-contrast, T1-weighted MR image showed soft-tissue enhancement (arrow) with central non-enhancement before chemotherapy. C. Axial PET-CT image demonstrated increased FDG uptake (SUVmax = 21.84) in corresponding lesion. D. Axial, T2-weighted MR image obtained after chemotherapy shows decrease in tumor size. E. Axial, post-contrast, T1-weighted MR image obtained after chemotherapy shows decrease in area of soft-tissue enhancement (arrow). F. Corresponding to fused FDG-MR/PET image obtained after chemotherapy and which showed no pathological FDG uptake (SUVmax = 2.23). FDG = fluorodeoxyglucose, MR/PET = magnetic resonance imaging/positron emission tomography, SUVmax = maximum standardized uptake value
Mentions: Moreover, MR/PET could provide the information regarding not only the treatment response but also the restaging for surgical resection after neoadjuvant treatment in a single session (Figs. 7, 8). Currently, there are only a few reports that assess the potential benefit of MR/PET in the treatment response evaluation. Platzek et al. (90) evaluated the feasibility of sequential MR/PET for the therapy response evaluation of malignant lymphoma in nine patients. They showed excellent interobserver agreement regarding the Ann Arbor stage (κ = 0.97) and good interobserver agreement regarding the image quality (κ = 0.41), thus suggesting that FDG-MR/PET is a reliable imaging method. Schuler et al. (71) reported a case of rhabdomyosarcoma for which MR/PET was used to guide neoadjuvant treatment. They were able to determine whether neoadjuvant chemotherapy was effective after the response evaluation made with MR/PET, and then could perform curable resection at the optimal time. This case demonstrates that MR/PET could be a valuable method for solving clinical problems. Based on these reports, MR/PET is expected to offer a great opportunity for tumor-response evaluation and treatment monitoring. However, both PET and DWI are weak in their ability to differentiate viable tumor from inflammation/granulation tissue after neoadjuvant treatment, although for different reasons. The simultaneous acquisition of PET and MR images may be complementary to each other. The addition of a functional component, such as perfusion MR, could help detect early responders in patients undergoing neoadjuvant therapy, giving meaningful information to determine whether a further chemotherapy cycle is needed. In addition, MR/PET can provide additional meaningful information regarding the decision-making process for clinicians, and which will be advantageous for patients who require neoadjuvant chemotherapy or radiation therapy.

Bottom Line: This review provides an overview of the technical background of combined MR/PET systems, a discussion of the potential advantages and technical challenges of hybrid MR/PET instrumentation, as well as collection of possible solutions.Various early clinical applications of integrated MR/PET are also addressed.Finally, the workflow issues of integrated MR/PET, including maximizing diagnostic information while minimizing acquisition time are discussed.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Seoul National University Hospital, Seoul 110-744, Korea.

ABSTRACT
Whole body integrated magnetic resonance imaging (MR)/positron emission tomography (PET) imaging systems have recently become available for clinical use and are currently being used to explore whether the combined anatomic and functional capabilities of MR imaging and the metabolic information of PET provide new insight into disease phenotypes and biology, and provide a better assessment of oncologic diseases at a lower radiation dose than a CT. This review provides an overview of the technical background of combined MR/PET systems, a discussion of the potential advantages and technical challenges of hybrid MR/PET instrumentation, as well as collection of possible solutions. Various early clinical applications of integrated MR/PET are also addressed. Finally, the workflow issues of integrated MR/PET, including maximizing diagnostic information while minimizing acquisition time are discussed.

Show MeSH
Related in: MedlinePlus