Evaluation of a Fast Protocol for Staging Lymphoma Patients with Integrated PET/MRI.
BACKGROUND
The aim of this study was to assess the applicability of a fast MR-protocol for whole-body staging of lymphoma patients using an integrated PET/MR system.


METHODS
A total of 48 consecutive lymphoma patients underwent 52 clinically indicated PET/CT and subsequent PET/MRI examinations with the use of 18F-FDG. For PET/MR imaging, a fast whole-body MR-protocol was implemented. A radiologist and a nuclear medicine physician interpreted MRI and PET/MRI datasets in consensus and were instructed to identify manifestations of lymphoma on a site-specific analysis. The accuracy for the identification of active lymphoma disease was calculated and the tumor stage for each examination was determined. Furthermore, radiation doses derived from administered tracer activities and CT protocol parameters were estimated and the mean scan duration of PET/CT and PET/MR imaging was determined. Statistical analysis was performed to compare the diagnostic performance of PET/MRI and MRI alone. The results of PET/CT imaging, all available histopathological samples as well as results of prior examinations and follow-up imaging were used for the determination of the reference standard.


RESULTS
Active lymphoma disease was present in 28/52 examinations. PET/MRI revealed higher values of diagnostic accuracy for the identification of active lymphoma disease in those 52 examinations in comparison to MRI, however, results of the two ratings did not differ significantly. On a site specific analysis, PET/MRI showed a significantly higher accuracy for the identification of nodal manifestation of lymphoma (p<0.05) if compared to MRI, whereas ratings for extranodal regions did not reveal a significant difference. In addition, PET/MRI enabled correct identification of lymphoma stage in a higher percentage of patients than MRI (94% vs. 83%). Furthermore, SUVs derived from PET/MRI were significantly higher than in PET/CT, however, there was a strong positive correlation between SUVmax and SUVmean of the two imaging modalities (R = 0.91 p<0.001 and R = 0.87, p<0.001). Average scan duration of whole-body PET/CT and PET/MRI examinations amounted to 17.3±1.9 min and 27.8±3.7 min, respectively. Estimated mean effective-dose for whole-body PET/CT scans were 64.4% higher than for PET/MRI.


CONCLUSIONS
Our results demonstrate the usefulness of 18F-FDG PET data as a valuable additive to MRI for a more accurate evaluation of patients with lymphomas. With regard to patient comfort related to scan duration and a markedly reduced radiation exposure, fast PET/MRI may serve as a powerful alternative to PET/CT for a diagnostic workup of lymphoma patients.
Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
Johannes
http://orcid.org/0000-0002-7560-8657
J
Grueneisen
Department of Diagnostic and Interventional Radiology, University Hospital Dusseldorf, University of Dusseldorf, Dusseldorf, Germany.
Lino Morris
LM
Sawicki
Department of Diagnostic and Interventional Radiology, University Hospital Dusseldorf, University of Dusseldorf, Dusseldorf, Germany.
Benedikt Michael
BM
Schaarschmidt
Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
Saravanabavaan
S
Suntharalingam
Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
Sara
S
von der Ropp
Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
Axel
A
Wetter
Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
Verena
V
Ruhlmann
Erwin L. Hahn Institute for Magnetic Resonance Imaging, University of Duisburg-Essen, Essen, Germany.|High Field and Hybrid MR Imaging, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
Harald H
HH
Quick
Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
Michael
M
Forsting
Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
Lale
L
Umutlu
D000328:Adult; D000368:Aged; D006801:Humans; D007682:Kidney Pelvis / Q000000981:diagnostic imaging / Q000473:pathology; D008198:Lymph Nodes / Q000473:pathology; D008223:Lymphoma / Q000175:diagnosis* / Q000000981:diagnostic imaging* / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D009367:Neoplasm Staging; D000072078:Positron Emission Tomography Computed Tomography; D049268:Positron-Emission Tomography / Q000379:methods*; D055815:Young Adult