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  • Journal Highlights

    The following are highlights from the current issues of RSNA’s two peer-reviewed journals.

    September 1, 2017

    10 Things You Might Not Know about Iron Oxide Nanoparticles

    Amid mounting concerns about nephrogenic sclerosis and gadolinium deposition in the brain, the search is underway for a safer alternative to gadolinium chelates for clinical MRI.

    Two ultra-small superparamagnetic iron oxide nanoparticles (USPIOs) are currently being used for clinical MRI applications: the FDA-approved iron supplement ferumoxytol (Feraheme) and ferumoxtran-10 (Combidex/Sinerem), which is undergoing renewed clinical trials in Europe.

    As these agents are starting to be used by a new generation of radiologists, important clinical questions have re-emerged, including those that have been answered in the past.

    In an online Radiology article, Heike E. Daldrup-Link, MD, PhD, of Stanford University, CA, addresses these newly resurfaced questions and offers 10 key insights into the use of iron oxide nanoparticles for clinical MRI, including:

    • USPIOs can cause immune responses through the classic Gell-Coombs pathway or complement-activated pseudo-allergy.

    • Dual-contrast MRI studies can be obtained after injecting iron oxides and then gadolinium chelates or vice versa.

    • Ferumoxytol enhancement of lymph nodes is not due to macrophage phagocytosis.

    Since USPIOs are not associated with a risk of nephrogenic sclerosis, they can serve as a safer contrast agents compared with gadolinium chelates for MR angiography, tissue perfusion studies and atherosclerotic plaque and tumor imaging, the author concludes.

    “USPIOs are especially beneficial for patients with renal insufficiency or patients with uncertain creatinine laboratory values,” the author writes. “New developments in USPIOs may spur new personalized diagnostic tests and theranostic (combined diagnostic and therapeutic) procedures.”

    This article meets the criteria for AMA PRA Category 1 Credit™. SA-CME is available online only.

    Clinical Imaging in Prostate Cancer

    Conventional imaging of prostate cancer has limitations in staging, restaging after biochemical relapse, and response assessment. PET has a rapidly evolving role in the assessment of prostate cancer, particularly in the scenario of biochemical relapse.

    While fluorine 18 (18F) fluorodeoxyglucose (18F-FDG) is the most widely available PET tracer, it has limitations, particularly in indolent prostate cancer. In the past decade, several PET tracers with specific molecular targets have reached the clinical domain, including 18F–sodium fluoride (18F-NaF), 11C-choline, 18F-choline, gallium 68–prostate­-specific membrane antigen ligands (68Ga-PSMA), and 18F-fluciclovine, a tracer recently approved by the U.S. Food and Drug Administration.

    In an article in the September-October issue of RadioGraphics, (RSNA.org/RadioGraphics), Kathryn L. Wallitt, MBBS, BSc, Charing Cross Hospital, London, and colleagues review the mechanisms of action of the clinically available PET tracers. The authors review the role of these tracers in the imaging of prostate cancer with reference to relevant guidelines and discuss the benefits and limitations for each tracer and the optimum clinical scenario for use. The authors also identify the molecular targets of these tracers and describe the required preparation and common image acquisition procedures.

    “A particular strength of PET imaging is early detection of disease in patients with biochemical relapse, a strength that provides the opportunity for a personalized approach or precision medicine with localized salvage therapy or the treatment of oligometastatic disease, with the intention of possible cure or improved outcomes,” the authors conclude.

    Further research into the optimal clinical utility of these PET tracers and their cost-ef-ectiveness is awaited and will likely be reflected in the clinical guidelines in the future, the authors write.

    This article meets the criteria for AMA PRA Category 1 Credit™. SA-CME is available online only.

    Radiology Podcasts

    Radiology Podcasts 

    Listen to Radiology Editor Herbert Y. Kressel, MD, deputy editors and authors discuss the following articles in the July issue of Radiology RSNA.org/Radiology-Podcasts.

    The first podcast is a roundtable discussion with the authors of these articles:

    • “Prostate Cancer: Diffusion-weighted MR Imaging for Detection and Assessment of Aggressiveness —
      Comparison between Conventional and Kurtosis Models,” Tsutomu Tamada, MD, Vinay Prabhu, MD, MS, Jianhong Li, MD, James S. Babb, PhD, Samir S. Taneja, MD, and Andrew B. Rosenkrantz, MD.
    • “Diffusion-Tensor Imaging of the Physes: A Possible Biomarker for Skeletal Growth —
      Experience with 151 Children,” Maria A. Bedoya, MD, Jorge Delgado, MD,
      Jeffrey I. Berman, PhD, Nancy A. Chauvin, MD, David Zurakowski, MS, PhD,
      Raul Ramirez-Grueso, PhD, Aikaterini Ntoulia, MD, PhD, and Diego Jaramillo, MD, MPH

    RadioGraphics Podcasts

    Radiology Podcasts

    Listen to RadioGraphics Editor Jeffrey S. Klein, MD, and authors discuss the following article in the July-August issue of RadioGraphics atpubs.RSNA.org/Page/RadioGraphics/Views.

    • “Beyond the Bowel: Extraintestinal Manifestations of Inflammatory Bowel Disease,” Jeffrey D. Olpin, MD, and colleagues.

    Ferumoxytol-enhanced MR imaging of a normal lymph node with histopathologic correlation. A, Axial T2-weighted fast spin-echo (5700/25) image through the lower abdomen of a Sprague-Dawley rat shows normal lymph node in the right inguinal region (arrow). B, At 24 hours after intravenous injection of fluorescein isothiocyanate (FITC)-conjugated ferumoxytol at a dose of 30 mg iron per kilogram, the lymph node shows marked signal loss (arrow). C, Corresponding hematoxylin-eosin histopathologic slice shows normal lymph node architecture (magnification, ´40). D, Prussian blue staining shows iron containing cells (arrows; magnification, ´40). E, F, Confocal microscopy of the same lymph node shows numerous cells with intracellular FITC ferumoxytol (green) and only few macrophages (red, stained with rhodamin-labeled anti-CD68 mAb; blue = DAPI [49,6-diamidino-2-phenylindole]; magnification, ´40). Not all macrophages contain FITC-ferumoxytol and numerous cells that do contain FITC-ferumoxytol are apparently not macrophages. (Radiology 2017;284;3:InPress) © RSNA 2017. All rights reserved. Printed with permission.

    18F-Choline PET/CT for evaluation for relapse in a 74-year-old man with a rising PSA level after external beam radiation therapy. Axial fused PET/CT images (b obtained higher than a) show recurrence in the left seminal vesicle (arrow on a), as well as an unusual site of disease in peritoneal deposits in the right paracolic gutter (arrowhead on b). For the peritoneal deposits, the findings at histopathologic examination of the specimen from biopsy helped confirm the recurrence. (RadioGraphics 2017; 37; 5:InPress) RSNA 2017. All rights reserved. Printed with permission.