Abstract
ObjectivesThe present study aims to compare the diagnostic efficacy of MR, 18F-FDG PET/CT, and 18F-FDG PET/MR for the local detection of early-stage extranodal natural killer/T-cell lymphoma, nasal type (ENKTL).Patients and MethodsThirty-six patients with histologically proven early-stage ENKTL were enrolled from a phase 2 study (Cohort A). Eight nasopharyngeal anatomical regions from each patient were imaged using 18F-FDG PET/CT and MR. A further nine patients were prospectively enrolled from a multicenter, phase 3 study; these patients underwent 18F-FDG PET/CT and PET/MR after a single 18F-FDG injection (Cohort B). Region-based sensitivity and specificity were calculated. The standardized uptake values (SUV) obtained from PET/CT and PET/MR were compared, and the relationship between the SUV and apparent diffusion coefficients (ADC) of PET/MR were analyzed.ResultsIn Cohort A, of the 288 anatomic regions, 86 demonstrated lymphoma involvement. All lesions were detected by 18F-FDG PET/CT, while only 70 were detected by MR. 18F-FDG PET/CT exhibited a higher sensitivity than MR (100% vs. 81.4%, χ2 = 17.641, P < 0.001) for local detection of malignancies. The specificity of 18F-FDG PET/CT and MR were 98.5 and 97.5%, respectively (χ2 = 0.510, P = 0.475). The accuracy of 18F-FDG PET/CT was 99.0% and the accuracy of MR was 92.7% (χ2 = 14.087, P < 0.001). In Cohort B, 72 anatomical regions were analyzed. PET/CT and PET/MR have a sensitivity of 100% and a specificity of 92.5%. The two methods were consistent (κ = 0.833, P < 0.001). There was a significant correlation between PET/MR SUVmax and PET/CT SUVmax (r = 0.711, P < 0.001), and SUVmean (r = 0.685, P < 0.001). No correlation was observed between the SUV and the ADC.ConclusionIn early-stage ENKTL, nasopharyngeal MR showed a lower sensitivity and a similar specificity when compared with 18F-FDG PET/CT. PET/MR showed similar performance compared with PET/CT.
Highlights
Extranodal natural killer/T-cell lymphoma, nasal type (ENKTL) is a rare and distinct entity of extranodal non-Hodgkin lymphoma (NHL), which is more prevalent in Asia [1,2,3]
The present study aims to compare the diagnostic efficacy of Magnetic resonance (MR), 18F-FDG PET/CT, and 18F-FDG PET/MR for the local detection of early-stage extranodal natural killer/T-cell lymphoma, nasal type (ENKTL)
All lesions were detected by 18F-FDG PET/CT, while only 70 were detected by MR. 18F-FDG PET/CT exhibited a higher sensitivity than MR (100% vs. 81.4%, χ2 = 17.641, P < 0.001) for local detection of malignancies
Summary
Extranodal natural killer/T-cell lymphoma, nasal type (ENKTL) is a rare and distinct entity of extranodal non-Hodgkin lymphoma (NHL), which is more prevalent in Asia [1,2,3]. Since almost 75% of patients present earlystage I or II disease within the nasal cavity and adjacent sites [4], radiotherapy is routinely performed on these patients [5]. It is very important to define the extent of tumor invasion and observe regional structures in ENKTL to assess its complexity in the nasal cavity and surrounding areas [6,7,8]. Magnetic resonance (MR) with diffusion-weighted imaging (DWI) has been reported to better distinguish the extent of tumor invasion in earlystage ENKTL owing to its ability to reveal fine anatomical details [15]; the technique still warrants further validation. The diagnostic efficacy of PET/MR in early-stage ENKTL has never been assessed
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