No abstract

The inability to visualize the initiation and progression of type-1 diabetes (T1D) noninvasively in humans is a major research and clinical stumbling block. We describe an advanced, exportable method for imaging the pancreatic inflammation underlying T1D, based on MRI of the clinically approved magnetic nanoparticle (MNP) ferumoxytol. The MNP-MRI approach, which reflects nanoparticle uptake by macrophages in the inflamed pancreatic lesion, has been validated extensively in mouse models of T1D and in a pilot human study. The methodological advances reported here were enabled by extensive optimization of image acquisition at 3T, as well as by the development of improved MRI registration and visualization technologies. A proof-of-principle study on patients recently diagnosed with T1D versus healthy controls yielded two major findings: First, there was a clear difference in whole-pancreas nanoparticle accumulation in patients and controls; second, the patients with T1D exhibited pronounced inter-and intrapancreatic heterogeneity in signal intensity. The ability to generate noninvasive, 3D, high-resolution maps of pancreatic inflammation in autoimmune diabetes should prove invaluable in assessing disease initiation and progression and as an indicator of response to emerging therapies.autoimmune diabetes | magnetic resonance imaging | nanoparticle | insulitis | pancreas

Background: The diagnostic yield of cardiac sarcoidosis (CS) by endomyocardial biopsy is limited. Fluorodeoxyglucose (FDG) positron emission tomography (PET) and cardiac magnetic resonance imaging (MRI) may facilitate noninvasive diagnosis, but the accuracy of this approach is not well defined. We aimed to correlate findings from FDG PET and cardiac MRI with histologic findings from explanted hearts of patients who underwent cardiac transplantation. Methods: We analyzed the explanted heart histology for all patients who underwent cardiac transplant at our center from April 2008 to July 2018 and had pre-transplant FDG PET (n=18) or cardiac MRI (n=31). The likelihood of CS based on FDG PET or cardiac MRI was categorized in a blinded fashion using a previously published method. Results: Using a CS probable cutoff for FDG PET resulted in a sensitivity of 100.0% (95% CI: 54.1% to 100.0%) and a specificity of 33.3% (95% CI: 9.9%-65.1%). Three of the nine CS probable by FDG PET cases were found to be arrhythmogenic cardiomyopathy. The test