ABSTRACT
BACKGROUND: We propose a new approach to facilitate sentinel node biopsy examination by multimodality imaging in which radioactive and near-infrared (NIR) fluorescent nanoparticles depict deeply situated sentinel nodes and fluorescent nodes with anatomical resolution in the surgical field. For this purpose, we developed polyamidoamine (PAMAM)-coated silica nanoparticles loaded with technetium-99m (99mTc) and indocyanine green (ICG). METHODS: We conducted animal studies to test the feasibility and utility of this dual-modality imaging probe. The mean diameter of the PAMAM-coated silica nanoparticles was 30 to 50 nm, as evaluated from the images of transmission electron microscopy and scanning electron microscopy. The combined labeling with 99mTc and ICG was verified by thin-layer chromatography before each experiment. A volume of 0.1 ml of the nanoparticle solution (7.4 MBq, except for one rat that was injected with 3.7 MBq, and 1 µg of an ICG derivative [ICG-sulfo-OSu]) was injected submucosally into the tongue of six male Wistar rats. RESULTS: Scintigraphic images showed increased accumulation of 99mTc in the neck of four of the six rats. Nineteen lymph nodes were identified in the dissected neck of the six rats, and a contact radiographic study showed three nodes with a marked increase in uptake and three nodes with a weak uptake. NIR fluorescence imaging provided real-time clear fluorescent images of the lymph nodes in the neck with anatomical resolution. Six lymph nodes showed weak (+) to strong (+++) fluorescence, whereas other lymph nodes showed no fluorescence. Nodes showing increased radioactivity coincided with the fluorescent nodes. The radioactivity of 15 excised lymph nodes from the four rats was assayed using a gamma well counter. Comparisons of the levels of radioactivity revealed a large difference between the high-fluorescence-intensity group (four lymph nodes; mean, 0.109% ± 0.067%) and the low- or no-fluorescence-intensity group (11 lymph nodes; mean, 0.001% ± 0.000%, p < 0.05). Transmission electron microscopy revealed that small black granules were localized to and dispersed within the cytoplasm of macrophages in the lymph nodes. CONCLUSION: Although further studies are needed to determine the appropriate dose of the dual-imaging nanoparticle probe for effective sensitivity and safety, the results of this animal study revealed a novel method for improved node detection by a dual-modality approach for sentinel lymph node biopsy.
ABSTRACT
Nodular fasciitis (NF) is a benign reactive lesion of the soft tissues related to the fascia and characterized by fibroblastic proliferation. The most common site is the upper extremities (46%), followed by the head and neck region (20%). In the orofacial region, the lesion typically develops within the subcutaneous structures overlying the angle and inferior border of the mandible and the zygoma. Magnetic resonance imaging (MRI) findings of NF in the orofacial region are almost unreported in the literature. In the present case report, we describe MRI findings of mental NF in a 19-year-old woman. MRI revealed a well-defined, round soft-tissue mass lying on the mentum. On T1-weighted MRI, the lesion was isointense to skeletal muscle; it was hyperintense to skeletal muscle on T2-weighted MRI, and was enhanced by Gd-diethylenetriamine pentaacetic acid (DTPA). Histologic examination revealed abundant myxoid degeneration dispersed in the lesion. The T2-weighted higher heterogeneous signal intensity was likely due to abundant myxoid degeneration or the cellular component of the lesion. A strong bright signal intensity belt appeared in the periphery of the lesion on Gd-DTPA enhancement. This rim enhancement appeared to represent small arterioles and venules that were visible in the peripheral area on histologic examination.
