Optimized Whole-Body PET MRI Sequence Workflow in Pediatric Hodgkin Lymphoma Patients

Abstract

F-FDG PET/MRI might be the diagnostic method of choice for Hodgkin lymphoma patients, as it combines significant metabolic information from PET with excellent soft-tissue contrast from MRI and avoids radiation exposure from CT. However, a major issue is longer examination times than for PET/CT, especially for younger children needing anesthesia. Thus, a targeted selection of suitable whole-body MRI sequences is important to optimize the PET/MRI workflow. Methods: The initial PET/MRI scans of 84 EuroNet-PHL-C2 study patients from 13 international PET centers were evaluated. In each available MRI sequence, 5 PET-positive lymph nodes were assessed. If extranodal involvement occurred, 2 splenic lesions, 2 skeletal lesions, and 2 lung lesions were also assessed. A detection rate was calculated dividing the number of visible, anatomically assignable, and measurable lesions in the respective MRI sequence by the total number of lesions. Results: Relaxation time-weighted (T2w) transverse sequences with fat saturation (fs) yielded the best result, with detection rates of 95% for nodal lesions, 62% for splenic lesions, 94% for skeletal lesions, and 83% for lung lesions, followed by T2w transverse sequences without fs (86%, 49%, 16%, and 59%, respectively) and longitudinal relaxation timeweighted contrast-enhanced transverse sequences with fs (74%, 35%, 57%, and 55%, respectively). Conclusion: T2w transverse sequences with fs yielded the highest detection rates and are well suited for accurate whole-body PET/MRI in lymphoma patients. There is no evidence to recommend the use of contrast agents.

[18F]FDG PET/MRI in children suffering from lymphoma: does MRI contrast media make a difference?

“…In line with the current literature, both reading protocols had a high sensitivity, specificity, positive predictive value, negative predictive value, and accuracy above 89% concordant to previous publications [ 36 , 59 ]. Our results clearly support the increasing trend of MRI contrast agent–free [ 18 F]FDG PET/MR imaging in pediatric lymphoma patients [ 26 – 29 ]. This is from particular importance to skip the potential risk of gadolinium deposition to in the brain (dentate nucleus/paleostriatum) and bone due to repetitive application of linear, gadolinium-based contrast agents [ 23 , 24 , 60 ].…”

“…The need for MRI contrast agent application in PET/MRI is clinically not debatable in individual tumor entities for further classification, such as liver or pelvic tumors [ 46 – 48 ]. Contrary, first publications have already shown that especially in pediatric lymphoma patients, a MRI contrast agent application might be waived for staging [ 13 , 29 ]. MRI contrast–free [ 18 F]FDG PET/MRI imaging protocols are able to outperform a radiation-saving [ 18 F]FDG PET/CT low-dose protocol with a more accurate soft tissue contrast and its well-known advantages when imaging parenchymal organs [ 13 , 29 ].…”

“…Contrary, first publications have already shown that especially in pediatric lymphoma patients, a MRI contrast agent application might be waived for staging [ 13 , 29 ]. MRI contrast–free [ 18 F]FDG PET/MRI imaging protocols are able to outperform a radiation-saving [ 18 F]FDG PET/CT low-dose protocol with a more accurate soft tissue contrast and its well-known advantages when imaging parenchymal organs [ 13 , 29 ]. Furthermore, they profit from simultaneously acquired metabolic PET imaging data that has been shown to be beneficial for staging, therapy monitoring, and differentiation between active and non-active lymphoma diseases [ 15 – 17 , 49 ].…”

“…This study revealed that the application of contrast agents does not lead to a noticeable improvement of the diagnostic accuracy of a PET/MRI staging [ 13 ]. Nonetheless, data about the value of MRI contrast agent application in [ 18 F]FDG PET/MRI in the diagnostic work-up of pediatric lymphoma patient is still limited to few small cohort studies [ 26 – 29 ].…”

Kommentar zu „KINDER – Lymphomstaging und -restaging mit der kontrastmittelfreien FDG-PET/MRT“

“…Die Autoren kommen zu vergleichbaren Ergebnissen wie eine aktuelle Multicenterstu-die, die für pädiatrische Hodgkin-Lymphome publiziert wurde [5]. In beiden Studien konnte gezeigt werden, dass eine Kontrastmittelapplikation keine nennenswerten Vorteile beim Staging und bei der Response-Beurteilung bringt.…”