Research Article Heterogeneous Enhancement Pattern in DCE-MRI Reveals the Morphology of Normal Lymph Nodes: An Experimental Study Pietro Bontempi , 1,2 Alice Busato, 2 Giamaica Conti, 3 Sabino Walter Della Sala, 4 Pasquina Marzola , 2 and Paolo Farace 1 1 Proton erapy Department, S. Chiara Hospital, Trento, Italy 2 Department of Computer Science, University of Verona, Verona, Italy 3 Department of Neuroscience and Biomedicine, University of Verona, Verona, Italy 4 Radiology Department, S. Maria del Carmine Hospital, Rovereto, Italy Correspondence should be addressed to Pietro Bontempi; pietro.bontempi@univr.it Received 25 September 2018; Revised 7 February 2019; Accepted 27 February 2019; Published 4 April 2019 Academic Editor: Mar´ ıa L. Garc´ ıa-Mart´ ın Copyright © 2019 Pietro Bontempi et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Purpose. To investigate the heterogeneous enhancement pattern in normal lymph nodes of healthy mice by different albumin- binding contrast agents. Methods. e enhancement of normal lymph nodes was assessed in mice by dynamic contrast-enhanced MRI (DCE-MRI) after the administration of two contrast agents characterized by different albumin-binding properties: gadopentetate dimeglumine (Gd-DTPA) and gadobenate dimeglumine (Gd-BOPTA). To take into account potential hetero- geneities of the contrast uptake in the lymph nodes, k-means cluster analysis was performed on DCE-MRI data. Cluster spatial distribution was visually assessed. Statistical comparison among clusters and contrast agents was performed on semiquantitative parameters (AUC, wash-in rate, and wash-out rate) and on the relative size of the segmented clusters. Results. Cluster analysis of DCE-MRI data revealed at least two main clusters, localized in the outer portion and in the inner portion of each lymph node. With both contrast agents, AUC (p < 0.01) and wash-in (p < 0.05) rates were greater in the inner cluster, which also showed a steeper wash-out rate than the outer cluster (Gd-BOPTA, p < 0.01; Gd-DTPA, p  0.056). e size of the outer cluster was greater than that of the inner cluster by Gd-DTPA (p < 0.05) and Gd-BOPTA (p < 0.01). e enhancement pattern of Gd-DTPA was not significantly different from the enhancement pattern of Gd-BOPTA. Conclusion. DCE-MRI in normal lymph nodes shows a characteristic heterogeneous pattern, discriminating the periphery and the central portion of the lymph nodes. Such a pattern deserves to be investigated as a diagnostic marker for lymph node staging. 1. Introduction Dynamic contrast-enhanced MRI (DCE-MRI) has been widely used to quantify tissue perfusion in preclinical [1, 2] and clinical studies. In DCE-MRI, multiple T1-weighted images are acquired before and at different time points after the administration of a Gd-based contrast agent, allowing the quantification of parameters related to perfu- sion [1, 2]. e diagnostic usefulness of DCE-MRI in tumors largely relies on the peculiar features of the tumor tissue: increased blood volume fraction and vessel permeability. anks to high-resolution T1-weighted images, DCE- MRI has been extensively applied in clinical studies to characterize the breast [3] and solitary pulmonary nodules [4] and in general in cancer diagnosis including the prostate [5] and liver [6]. Moreover, DCE-MRI can have a role for the detection and characterization of lymph nodes. Quantitative or semiquantitative parameters extracted from DCE-MRI data (describing, for example, the uptake and wash-out of the contrast agent) are expected to discriminate between positive and negative nodes. Accordingly, DCE-MRI showed promising performance to assess suspicious lymph nodes at different sites, such as the head and neck [7–9], rectal [10, 11], and cervical [12–14] and in the axillary lymph nodes in breast cancer patients [15–19], for which the role of MRI, including DCE-MRI, was recently reviewed [20]. Hindawi Contrast Media & Molecular Imaging Volume 2019, Article ID 4096706, 9 pages https://doi.org/10.1155/2019/4096706