An attempt to characterize malignant lymphoma in spleen, liver and lymph nodes with magnetic resonance imaging

Abstract

An attempt was made to explore whether relaxation times and/or normalized image intensities obtained from magnetic resonance imaging (MRI) can separate malignant and non-malignant lymphomatous tissue. Spin-echo (SE) techniques with repetition times of 500 and 1,500 ms and echo times of 35 and 70 ms were used for estimating T1 and T2. Estimation of T1 and T2 with such a low number of spin-echo sequences resulted in considerable variation in the data especially when T1 was long. Similar information was also extracted by normalizing the image intensities to the 'proton density' image (1,500/35), and the spread of the data was then markedly reduced. Therefore, the method of normalizing was considered a more appropriate way of handling the image data when only a few sequences were available. No significant difference could be discerned in the MRI parameters between normal spleens and spleens infiltrated with malignant lymphoma, between normal livers and livers in patients with malignant lymphoma and between lymph nodes with low or high grade non-Hodgkin lymphoma. Lymphomatous tissue had similar MRI characteristics irrespectively of whether the cells were malignant or not, or located in spleens or in lymph nodes. The main biologic explanation for variation in data seems to be mostly the variable amounts of fibrosis, necrosis, oedema and/or iron content.