Molecular imaging of angiogenesis to delineate the tumor margins in glioma rat model with endoglin-targeted paramagnetic liposomes using 3T MRI.

PURPOSE: To evaluate the use of endoglin-targeted paramagnetic liposomes in delineating the glioma margins using magnetic resonance (MR) angiogenesis imaging in a rat model. MATERIALS AND METHODS: Four liposome preparations, including nontargeted paramagnetic liposomes (Gd-SLs), isotype control IgG-coupled paramagnetic liposomes (IgG-Gd-SLs), endoglin monoclonal antibody coupled paramagnetic liposomes (MAb-Gd-SLs), and biotinylated antibodies (Bio-MAb)/streptavidin-coupled paramagnetic liposomes (SAv-Gd-SLs) for two-step pretargeting imaging, were formulated. All animal experiments were carried out with the approval of the Shanghai Animal Care. C6 glioma-bearing Sprague-Dawley rats were intravenously injected with gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA) or the previously mentioned liposomes (n = 5) and imaged with MR. T1 -weighted MRI was performed before and dynamically repeated after different contrast agents were injected. The enhancement features of the tumors were compared. RESULTS: The signal enhancement of the tumor in the two-step pretargeting group increased by 117.9 ± 5.3% at the periphery and 109.2 ± 3.5% in the center (P = 0.032) at the 8-hour timepoint after SAv-Gd-SLs injection. Ring-like enhancement margins were demonstrated at the periphery of the tumor in the two-step targeted group. The specificity of the targeted liposomes was supported by the competitive study. The signal of peak enhancement using MAb-Gd-SLs was 59% less than that of the two-step group and only slightly higher than the non-targeted groups. CONCLUSION: The two-step endoglin-targeted imaging using biotin-streptavidin interaction was demonstrated to induce intense enhancement of the tumor periphery, which implies that this advanced MR molecular contrast agent may be suitable for accurately delineating glioma tumor margins. J. Magn. Reson. Imaging 2015;41:1056-1064. © 2014 Wiley Periodicals, Inc.

Imaging characteristics of Rosai-Dorfman disease in the central nervous system.

BACKGROUND AND PURPOSE: Rosai-Dorfman disease (RDD) is a rare, lymphoproliferative disorder of uncertain etiology. The Central Nervous System (CNS) is a very rare site for RDD and only a few imaging appearances have been described. The purpose of this study is to present the largest series of cases in the CNS imaging literature to increase familiarity with this entity and further identify features that may distinguish RDD from meningioma. MATERIALS AND METHODS: Findings from imaging examinations in 10 patients with pathologically confirmed RDD were retrospectively reviewed. Two radiologists evaluated the lesion location, shape, size, number, edge, cerebral edema, homogeneous or heterogeneous appearance, attenuation and signal intensity, degree of enhancement, and the relation between lesions and meninges. RESULTS: RDD in CNS showed similar features in imaging: an extra-axial, well-circumscribed, dura-based mass, isodense or hyperdense on CT, isointensity on T1-weighted imaging and isointensity with hypointensity on T2-weighted imaging. The mass enhanced markedly and homogeneously after the administration of contrast agent and demonstrated dural tail sign in all cases. Significant perifocal edema was associated with the masses. Remarkably, seven patients (77.8%) showed strong hypointensity within isointensity on T2-weighted or FLAIR images and no calcification was observed in CT images or pathologic specimens. CONCLUSIONS: Although RDD in the CNS is a rare process, it should be considered in the differential diagnoses for meningioma. We believe that a typical representation of hypointensity irrelevant to calcification on T2-weighted or FLAIR images can suggest the diagnosis of RDD.

Imaging Findings of Follicular Dendritic Cell Sarcoma: Report of Four Cases

Follicular dendritic cell sarcoma is a rare malignant neoplasm and little is known about its radiological features. We present here four cases of follicular dendritic cell sarcomas and we provide the image characteristics of these tumors to help radiologists recognize this entity when making a diagnosis.