18F-FDG-PET/MR increases diagnostic confidence in detection of bone metastases compared with 18F-FDG-PET/CT

Abstract

PURPOSE: The aim of this study was to compare detection, lesion conspicuity and reader confidence of F-fluorodeoxyglucose (F-FDG)-PET/MR and F-FDG-PET/computed tomography (CT) in patients with F-FDG avid bone metastases. MATERIALS AND METHODS: In this prospective study, a total of 30 PET/CT and PET/MRI data sets were performed in 24 patients. Each examination was evaluated for the presence of PET-positive bone lesions consistent with metastatic involvement. Conspicuity of PET-positive bone lesions was evaluated on the corresponding PET/CT and PET/MR images and compared using the Wilcoxon signed-ranks test. Reader confidence was determined to evaluate whether PET/CT or PET/MR was more useful for the assessment of the bone metastases and was compared using Student's t-test. RESULTS: Overall, in both examinations, PET/CT and PET/MRI detected 86 F-FDG-positive bone lesions. On all 30 PET/MRI examinations, at least one morphological correlate for F-FDG-positive bone lesions was found on the MR component (82 out of 86 lesions). PET/CT imaging allowed identification of corresponding structural changes on the CT component in 23 out of 30 studies (65 out of 86 lesions). In lesion-by-lesion analysis, the mean lesion conspicuity was significantly better on T1 fat MR imaging compared with CT imaging (P=0.005). In seven out of 30 studies, a significant increase in reader confidence of PET/MRI compared with PET/CT was found. CONCLUSION: PET/MRI offers higher reader confidence and improved conspicuity in bone metastases compared with PET/CT. However, the overall detection rate was not different. The highest possible clinical impact of PET/MRI appears to be in patients with limited, early bone metastatic disease. Materials and methods In this prospective study, a total of 30 PET/CT and PET/MRI data sets were performed in 24 patients. Each examination was evaluated for the presence of PET-positive bone lesions consistent with metastatic involvement. Conspicuity of PET-positive bone lesions was evaluated on the corresponding PET/CT and PET/MR images and compared using the Wilcoxon signed-ranks test. Reader confidence was determined to evaluate whether PET/CT or PET/MR was more useful for the assessment of the bone metastases and was compared using Student's t-test. In lesion-by-lesion analysis, the mean lesion conspicuity was significantly better on T1 fat MR imaging compared with CT imaging (P = 0.005). In seven out of 30 studies, a significant increase in reader confidence of PET/MRI compared with PET/CT was found.Conclusion PET/MRI offers higher reader confidence and improved conspicuity in bone metastases compared with PET/CT. However, the overall detection rate was not different. The highest possible clinical impact of PET/MRI appears to be in patients with limited, early bone metastatic disease. Nucl Med Commun 00:000-000

FDG Whole-Body PET/MRI in Oncology: a Systematic Review

“…Whole-body PET/MR showed better detection rate of malignant bone lesions than PET/CT (100 % vs. 94 %), whereas diagnostic confidence of benign bone lesions was higher in PET/CT [68]. MR T1-weighted images in PET/MRI provided more conspicuous results for delineating and differentiating bone lesions than CT [69,70]. Chemotherapy-related change of metabolic activity and fat density in proximal bone marrow can be evaluated by PET and MRI [71].…”

“…Delineate structural change more clearly T1 TSE sequence [69], fat component analysis by 3D dual-echo gradient sequence [70] DWI diffusion weighted imaging, SUV standardized uptake value, TSE turbo spin echo treatment target tissue [88]. FDG uptake in a suspicious lesion can be further characterized by adding morphologic and functional information from MRI [89].…”

Evaluation of Prostate Cancer with PET/MRI

“…However, in our experience, these errors do not significantly affect the visual conspicuity of lesions on PET/MRI if uptake is sufficient to be perceptible on PET/CT. Indeed, some have suggested that the combination of PET and MRI increases the diagnostic confidence of prostate bone metastases over that of PET/CT (36). Furthermore, regardless of the radiopharmaceutical used, this systematic bias for the underestimation of SUVs is expected to be present on each examination longitudinally, thus still allowing for accurate estimation of changes in SUV over time.…”

PET/MRI and PET/CT: is there room for both at the top of the food chain?

“…The remaining 13 publications report some evidence that PET/ MRI is superior to PET/CT for characterizing primary tumours, e.g. primary bone tumours [11][12][13] or oesophageal carcinoma [14], but do not demonstrate significant advantages of whole-body MRI over whole-body PET/CT for N or M staging [15][16][17][18][19][20][21][22][23][24].The introduction of PET/MRI was heralded as a technological breakthrough, and many expected a subsequent clinical revolution, with the newer modality vying to supersede PET/CT atop the diagnostic food chain just as the Burmese python is supplanting the American alligator in the Florida Everglades. However, none of the above-mentioned papers offers a definitive answer as to whether or not integrated and simultaneous PET/MR imaging is clinically more accurate than sequentially performed whole-body PET/CT and MRI dedicated to one body region registered in retrospect.…”

“…The remaining 13 publications report some evidence that PET/ MRI is superior to PET/CT for characterizing primary tumours, e.g. primary bone tumours [11][12][13] or oesophageal carcinoma [14], but do not demonstrate significant advantages of whole-body MRI over whole-body PET/CT for N or M staging [15][16][17][18][19][20][21][22][23][24].…”