Magnetic resonance imaging (MRI) was performed on 50 dogs with intracranial neoplasia. The following tumor features were assessed: axial origin, location, shape, growth pattern, MRI signal intensity, evidence for edema, and paramagnetic contrast enhancement. Histologic diagnoses included 5 intracranially invading nasal tumors, 7 pituitary tumors, 22 meningiomas, 6 choroid plexus tumors, 7 astrocytomas, 1 ependymoma, and 2 oligodendrogliomas. Axial origin, site, shape, and growth pattern were important diagnostic characteristics for tumor type. Signal intensity Magnetic resonance imaging (MRI) is the preferred imaging method for human beings with central nervous system disease, and it has become increasingly available and affordable for use in veterinary medicine. The MRI features of canine neurologic disease have been described, but histologic diagnoses have not been available in all instance^.'.^ In this study, MRI scans of 50 histologically diagnosed canine intracranial tumors were evaluated retrospectively to identify distinguishing characteristics. Materials and Methods Selection CriteriaDogs with clinical signs of intracranial disease were referred to Washington State University Veterinary Teaching Hospital. The dogs were evaluated using a standard diagnostic protocol as part of a phase I clinical trial for boron neutron capture therapy, which was conducted with approval from the Animal Care and Use Committee.4.' Most dogs in the study had been treated with corticosteroids at the time of imaging. All patients had a complete MRI brain scan and histologic diagnosis of intracranial tumor. Patients with potential metastatic intracranial neoplasia were not included in the study. From the Magnetic Resonance Scan ProtocolDetails of the MRI protocol have been described previously.' Briefly, MRI was performed with a 1.5 T magnet (General Electric Signa, Milwaukee, WI). Under general anesthesia, dogs were placed in sternal recumbency, and a sagittal localizer series (time of relaxation or TR = 400 msec/time to echo or TE = 20 msec) was performed to delineate subsequent transverse images. Transverse proton density-weighted images (PDWI) and TZ-weighted images (TZWI) were obtained with a multiple spin echo series at TR = 2000 msec with TE = 20 to 30 and 80 to 90 msec. Transverse and sagittal precontrast and postcontrast T1-weighted images (T1 WI) were performed using TR = 800 msec and TE = 20 msec. Three to 5 mm slices with an interslice gap of 0 to 1.5 mm were obtained from the foramen magnum rostrally through the cribriform plate.

Novel nanoscale theragnostic devices were successfully prepared through attachment of well defined, multifunctional polymer chains to gadolinium (Gd) metal-organic framework (MOF) nanoparticles. Copolymers of poly(N-isopropylacrylamide)-co-poly(N-acryloxysuccinimide)-co-poly(fluorescein O-methacrylate) were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. The succinimide functionality was utilized as a scaffold for attachment of both a therapeutic agent, such as methotrexate, and a targeting ligand, such as H-glycine-arginine-glycine-aspartate-serine-NH(2) peptide. Employment of a trithiocarbonate RAFT agent allowed for reduction of the polymer end groups to thiolates providing a means of copolymer attachment through vacant orbitals on the Gd(3+) ions at the surface of the Gd MOF nanoparticles. These versatile, nanoscale scaffolds were shown to be biocompatible and have cancer cell targeting, bimodal imaging, and disease treatment capabilities. This unique method provided a simple yet versatile route of producing polymer-nanoparticle theragnostic materials with an unprecedented degree of flexibility in the construct, potentially allowing for tunable loading capacities and spatial loading of targeting/treatment agents, while incorporating bimodal imaging capabilities through both magnetic resonance and fluorescence microscopy.

A novel surface modification technique was employed to produce a polymer modified positive contrast agent nanoparticle through attachment of well-defined homopolymers synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. A range of RAFT homopolymers including poly[N-(2-hydroxypropyl)methacrylamide], poly(N-isopropylacrylamide), polystyrene, poly(2-(dimethylamino)ethyl acrylate), poly(((poly)ethylene glycol) methyl ether acrylate), and poly(acrylic acid) were synthesized and subsequently used to modify the surface of gadolinium (Gd) metal-organic framework (MOF) nanoparticles. Employment of a trithiocarbonate RAFT agent allowed for reduction of the polymer end groups under basic conditions to thiolates, providing a means of homopolymer attachment through vacant orbitals on the Gd3+ ions at the surface of the Gd MOF nanoparticles. Magnetic resonance imaging (MRI) confirmed the relaxivity rates of these novel polymer modified structures were easily tuned by changes in the molecular weight and chemical structures of the polymers. When a hydrophilic polymer was used for modification of the Gd MOF nanoparticles, an increase in molecular weight of the polymer provided a respective increase in the longitudinal relaxivity. These relaxivity values were significantly higher than both the unmodified Gd MOF nanoparticles and the clinically employed contrast agents, Magnevist and Multihance, which confirmed the construct's ability to be utilized as a positive contrast nanoparticle agent in MRI. Further characterization confirmed that increased hydrophobicity of the polymer coating on the Gd MOF nanoparticles yielded minimal changes in the longitudinal relaxivity properties but large increases in the transverse relaxivity properties in the MRI.

No abstract

Identification of metastatic disease critically impacts the care and prognosis of patients with neoplasia. Multiple techniques exist for identifying the sentinel or first lymph node(s) that receive draining tumour lymph. Identification of the sentinel lymph node enables accurate tissue sampling for determination of lymphatic metastasis. The aims of this study were to develop a computed tomography (CT) protocol for identifying the sentinel lymph node in dogs with tumours of the head and neck. In addition, indirect CT lymphography was compared to lymphoscintigraphy and vital dye injection to determine which technique more reliably identified the sentinel lymph node. CT indirect lymphography using intratumoral injection of iodinated contrast identified draining lymphatic vessels in eight of 18 dogs and identified the sentinel lymph node in five of 18 dogs. CT indirect lymphography employing fourquadrant peritumoral injection of iodinated contrast identified draining lymphatic vessels in 18 of 20 dogs and identified the sentinel lymph node in 11 of 20 dogs. Vital dye injection and lymphoscintigraphy identified the sentinel lymph node in 17 of 18 and 20 of 20 dogs, respectively. Identified sentinel lymph nodes were either ipsilateral or bilateral to the primary tumour. Both CT techniques were found to be safe and simple. Peritumoral injection has the greatest promise for the detection of sentinel lymph nodes in various head and neck cancers using CT, while lymphoscintigraphy had the greatest success of the compared techniques.

A diagnosis of intracranial neoplasia in companion animals may be made by computed tomography (CT) or magnetic resonance imaging (MRI). MRI is the better method for detecting and characterizing intracranial tumors because of its superior depiction of soft tissues and relative lack of degrading artifacts, intracranial tumors may be characterized by distinct features; a systematic evaluation of these features on CT or MRI images may help to identify specific tumor types. In this article, guidelines for formulating differential diagnoses based on these imaging criteria will be discussed. Technical recommendations and protocols for CT and MR imaging will also be provided.

The Raman spectra of aragonite and dolomite have been measured to pressures of 23 and 28 GPa, respectively, and the infrared spectra of aragonite measured to 40 GPa. Results have also been obtained probing the spectra of aragonite at high pressures following laser‐heating to temperatures in excess of 2000 K, and of compressed dolomite during external heating to 800 K. Our spectral range, between 100 and 1400 cm−1, encompasses vibrations characteristic of both stretching and bending motions of the carbonate group, as well as lower frequency bands associated with lattice vibrations. The pressure shifts of the aragonite bands vary from −0.3 cm−1/GPa for the carbonate out‐of‐plane bend to 3.4 cm−1/GPa for a lattice mode, while those of dolomite lie between 1.1 cm−1/GPa (in‐plane carbonate bend) and 4.4 cm−1/GPa (lattice mode). Bands associated with vibrations of the carbonate ions have systematically smaller Grüneisen parameters than those associated with cation displacements, and we infer from the mode shifts of these low frequency vibrations that the bulk of the compression of these crystals is produced by the deformation and compaction of the metal ion environment. Indeed, the carbonate group remains stable and relatively undistorted throughout this pressure range, as manifested by the amount of splitting of the carbonate asymmetric stretching vibration (∼90 cm−1) at the highest pressures of these measurements (41 GPa). Neither aragonite nor dolomite are observed to undergo phase transitions over the pressure and temperature range of this study, documenting that these phases are notably stable under compression. Thus, carbon is likely to remain stably bound, possibly within carbonate phases, over a pressure range spanning those present in the upper mantle and shallow lower mantle.

Magnetic resonance imaging (MRI) examinations from 18 dogs with a histologically confirmed peripheral nerve sheath tumor (PNST) of the brachial plexus were assessed retrospectively. Almost half (8/18) had a diffuse thickening of the brachial plexus nerve(s), six of which extended into the vertebral canal. The other 10/18 dogs had a nodule or mass in the axilla (1.2-338 cm3). Seven of those 10 masses also had diffuse nerve sheath thickening, three of which extended into the vertebral canal. The majority of tumors were hyperintense to muscle on T2-weighted images and isointense on T1-weighted images. Eight of 18 PNSTs had only minimal to mild contrast enhancement and many (13/18) enhanced heterogeneously following gadolinium DTPA administration. Transverse plane images with a large enough field of view (FOV) to include both axillae and the vertebral canal were essential, allowing in-slice comparison to detect lesions by asymmetry of structures. Higher resolution, smaller FOV, multiplanar examination of the cervicothoracic spine was important for appreciating nerve root and foraminal involvement. Short tau inversion recovery, T2-weighted, pre and postcontrast T1-weighted pulse sequences were all useful. Contrast enhancement was critical to detecting subtle diffuse nerve sheath involvement or small isointense nodules, and for accurately identifying the full extent of disease. Some canine brachial plexus tumors can be challenging to detect, requiring a rigorous multiplanar multi-pulse sequence MRI examination.