Magnetic resonance imaging (MRI) and dynamic MRI evaluation of extranodal non-Hodgkin lymphoma in oral and maxillofacial regions

Objective. The purpose of this study was to evaluate the diagnostic value of magnetic resonance imaging (MRI), especially dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), in extranodal non-Hodgkin lymphoma (NHL) of oral and maxillofacial regions. Study design. Thirteen cases with extranodal NHL were examined using MRI. T1-weighted images (T1WI) and T2-weighted images (T2WI) or short TI inversion recovery (STIR) images were obtained in all cases. Contrast-enhanced images and DCEMRI were acquired in 10 and 7 cases, respectively. On DCE-MRIs, we analyzed the parameters as follows: contrast index at maximal contrast enhancement (CImax), maximum contrast index (CI) gain/CImax ratio, and washout ratios (WR300, WR600, and WR900) at 300, 600, and 900 seconds after contrast medium injection. Results. The signal intensity of all lesions was hypointense to isointense on T1WIs and showed variable contrast enhancement patterns. On T2WIs and STIR images, the signal intensity was isointense to hyperintense in almost all cases. Analysis of DCEMRI parameters in extranodal NHLs resulted in the identification of 4 types of CI curves according to CImax and WR: (1) CImax greater than 2.0 and WR900 greater than 40%, (2) CImax greater than 2.0 and WR900 less than 40%, (3) CImax less than 1.5 and WR900 greater than 40%, and (4) CImax less than 1.5 and WR900 greater than 40%. Conclusions. The signal intensities on MRI were not specific to extranodal NHL and resembled those of other tumor types. When CImax was less than 1.5 or WR900 was less than 40%, these parameters contributed to diagnosis in extranodal NHLs.