Can magnetic resonance spectroscopy differentiate malignant and benign causes of lymphadenopathy? An in-vitro approach.

Lionel Buré,Benoit Gallix,Stefan Schob,Louis-Martin Boucher,Miriam Blumenkrantz,Caroline Reinhold,Pierre Lafaye De Micheaux

doi:10.1371/journal.pone.0182169

Abstract

Lymphadenopathy continues to be a common problem to radiologists and treating physicians because of the difficulty in confidently categorizing a node as being benign or malignant using standard diagnostic techniques. The goal of our research was to assess whether magnetic resonance (MR) spectroscopy contains the necessary information to allow differentiation of benign from malignant lymph nodes in an in-vitro approach using a modern pattern recognition method. Tissue samples from a tissue bank were analyzed on a nuclear magnetic resonance (NMR) spectrometer. A total of 69 samples were studied. The samples included a wide variety of malignant and benign etiologies. Using 45 samples, we initially created a model which was able to predict if a certain spectrum originates from benign or malignant lymph nodes using a pattern-recognition technique which takes into account the entire magnetic spectrum rather than single peaks alone. The remaining 24 samples were blindly loaded in the model to assess its performance. We obtained an excellent accuracy in differentiating benign and malignant lymphadenopathy using the model. It correctly differentiated as malignant or benign, in a blinded fashion, all of the malignant samples (13 of 13) and 10 out of the 11 benign samples. We thus showed that magnetic spectroscopy is able to differentiate benign from malignant causes of lymphadenopathy. Additional experiments were performed to verify that the differentiating abilities of our model were not due to differential tissue decay in between benign and malignant tissues. If future experiments demonstrate that a similar approach could be executed with standard MR imaging, this technique could be useful as a problem-solving tool when assessing lymphadenopathy in general. Alternatively, our in-vitro technique could also be useful to pathologists faced with indeterminate pathologies of the lymph nodes after validating our results with a larger sample size.

Highlights

Assessment of lymphadenopathy remains one of the most challenging and often unsatisfactory issues for radiologists
The frozen tissues were allowed to be used for nuclear magnetic resonance (NMR) experiments only after the final pathological diagnosis was confirmed by the pathology department
The predominant peak in the spectra was in the 1–1.5ppm range, which is a composite of multiple lipids and lactate

Summary

Introduction

Assessment of lymphadenopathy remains one of the most challenging and often unsatisfactory issues for radiologists. In the neck, even in the setting of a known malignancy, up to 20% of lymph nodes that were deemed suspicious on imaging and subsequently biopsied are found to be benign [1]. Depending on the clinical setting, radiological assessment of lymphadenopathy is usually made using ultrasound (US), computerized tomography (CT), and conventional magnetic resonance imaging (MRI). These methods rely heavily on morphological characteristics, often solely based on the size of lymph nodes, which have a great degree of overlap between malignant and benign disease [2,3,4]. DWI performed only marginally better when evaluating lymphadenopathy in the neck, with an accuracy of 81% [6]

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