LAUSR

This prospective study sought to compare the diagnostic performance of advanced MR imaging (MRI) with PET/CT. In particular, we aimed to investigate whether MRI can decrease the false-positive or false-negative rate and could be a valid alternative to PET/CT evaluations. From December 2015 to May 2017, we enrolled 25 consecutive patients (17 females and 8 males aged 40.5 ± 16 years) with a histological diagnosis of lymphoma, and who had residual disease of ≥3 cm at the end of therapy. All patients underwent MRI and PET/CT 3–4 months after the end of immuno-chemotherapy and chemotherapy plus radiotherapy. The ethics committee of our institution approved this prospective study. All patients provided their written informed consent for the study, MRI, and PET/CT examination. MR images were acquired using a 1.5-T tomograph (Magnetom Aera, Siemens Healthcare, Germany). The MR protocol included ECG-gated sequences (T1-weighted [T1w], T2w, T2 SPAIR, and T1 FLASH before and after the administration of gadolinium chelate contrast agent), DwI, and PwI. The residual masses were analyzed by 2 radiologists experienced in MRI. They evaluated 3 parameters: morphological-contrastographic (MC) feaThe treatment of both Hodgkin’s lymphoma (HL) and non-Hodgkin’s lymphoma (NHL) frequently results in residual masses [1]. A high-prognostic-value imaging modality is needed to assess the response to treatment and identify patients with active disease within the residual mass. Positron emission tomography/computed tomography (PET/CT) allows for a complete assessment of the whole body and is now considered an essential tool to evaluate the posttreatment response in fluorodeoxyglucose (FDG)-avid lymphoma [2], although its accuracy is challenging. In long-term follow-up, often in young patients, an important issue to consider is the exposure to ionizing radiation. The mean effective dose of PET/CT examinations is 19.6 ± 6.1 mSv [3], corresponding with the radiation of about 1,000 chest X-rays and 10 head CTs [4]. Few studies have investigated the role of advanced magnetic resonance (MR) techniques by the 2 quantitative parameters, diffusion-weighted imaging (DwI) and perfusion-weighted imaging (PwI). DwI is able to provide an assessment of tumor cellular cramming, while PwI can quantitatively evaluate the combined effects of plasma blood flow, permeability, and capillary surface area. Received: October 25, 2017 Accepted after revision: November 18, 2017 Published online: January 26, 2018