Volume 55, Issue 4, Pages 761-769 (April 2009) Combined Ultrasmall Superparamagnetic Particles of Iron Oxide–Enhanced and Diffusion-Weighted Magnetic Resonance Imaging Reliably Detect Pelvic Lymph Node Metastases in Normal-Sized Nodes of Bladder and Prostate Cancer Patients  Harriet C. Thoeny, Maria Triantafyllou, Frederic D. Birkhaeuser, Johannes M. Froehlich, Dechen W. Tshering, Tobias Binser, Achim Fleischmann, Peter Vermathen, Urs E. Studer  European Urology  Volume 55, Issue 4, Pages 761-769 (April 2009) DOI: 10.1016/j.eururo.2008.12.034 Copyright © 2009 European Association of Urology Terms and Conditions

Fig. 1 Sixty-nine-year-old female patient with poorly differentiated muscle-invasive transitional cell carcinoma of the bladder. Typical order of the classic reading method: (A) Conventional axial reconstruction of T2-weighted magnetic resonance imaging (MRI) without contrast showing two normal-sized lymph nodes on both pelvic sides ( on the right distal external iliac region and on the left distal internal iliac region); (B) MRI obtained 24h after the administration of lymphotropic ultrasmall superparamagnetic particles of iron oxide (USPIO) results in a homogeneous signal decrease in the right normal lymph node (), while the left lymph node () presents a peripheral, partial signal decrease corresponding to malignancy; (C) the addition of USPIO–diffusion-weighted (DW) MRI to the classic reading method shows a focal, noncontinous hyperintense structure () adjacent to hyperintense bowel segments (★), corresponding to the malignant lymph node shown in Fig. 1B; (D) axial reconstruction of the three-dimensional volumetric interpolated breath-hold examination (VIBE) sequence at the same level depicted in Fig. 1A–C, with high signal intensities in the vessels allowing identification of the suspicious lymph node on the left side () and exact localization in relation to the vessel—the benign lymph node on the right side is no longer visible due to USPIO uptake; (E) histopathology shows immunohistochemically (pancytokeratin) stained metastasis (size: 4mm×1.8mm; arrows) in the suspicious lymph node () (size: 6mm×9.5mm) detected by imaging post USPIO–DW-MRI (compare Fig. 1C). The rest of the lymph node shows residual lymphoreticular tissue with follicular hyperplasia. European Urology 2009 55, 761-769DOI: (10.1016/j.eururo.2008.12.034) Copyright © 2009 European Association of Urology Terms and Conditions

Fig. 2 Fifty-year-old male patient with poorly differentiated prostate cancer and prostate-specific antigen (PSA) of 22.6 mcg/l. Typical order of the new reading method, starting with axial ultrasmall superparamagnetic particles of iron oxide (USPIO) combined with diffusion-weighted (DW) magnetic resonance imaging (MRI) showing (A) two hyperintense focal noncontinous structures that are suspicious for malignant lymph nodes (, ). The larger hyperintense structures toward the right side of the image correspond to bowel structures (★). (B) Axial reconstruction of the volumetric interpolated breath-hold examination (VIBE) sequence allows for localization of the two suspicious lymph nodes (, ) and differentiation from adjacent vessels (hyperintense). (C) Pre- and (D) post-USPIO axial reconstruction of T2-weighted MRI show identical signal intensities of the two suspicious lymph nodes (, ) corroborating malignancy. (D) A benign lymph node () anterior to the external iliac vessels shows USPIO uptake with signal decrease compared with Fig. 2C. Due to iron load, this node is not visible on USPIO–DW-MRI (Fig. 1A), explaining the ease of interpretation. (E) Histopathologic correlation of the smaller malignant lymph node () (size: 2mm×3mm) dissected from the right internal iliac region. Hematoxylin-eosin (HE)–stained section confirms metastasis from prostate cancer (arrows) subtotally replacing the lymphoreticular tissue. European Urology 2009 55, 761-769DOI: (10.1016/j.eururo.2008.12.034) Copyright © 2009 European Association of Urology Terms and Conditions