Nuclear molecular imaging with nanoparticles: radiochemistry, applications and translation.

Molecular imaging provides considerable insight into biological processes for greater understanding of health and disease. Numerous advances in medical physics, chemistry and biology have driven the growth of this field in the past two decades. With exquisite sensitivity, depth of detection and potential for theranostics, radioactive imaging approaches have played a major role in the emergence of molecular imaging. At the same time, developments in materials science, characterization and synthesis have led to explosive progress in the nanoparticle (NP) sciences. NPs are generally defined as particles with a diameter in the nanometre size range. Unique physical, chemical and biological properties arise at this scale, stimulating interest for applications as diverse as energy production and storage, chemical catalysis and electronics. In biomedicine, NPs have generated perhaps the greatest attention. These materials directly interface with life at the subcellular scale of nucleic acids, membranes and proteins. In this review, we will detail the advances made in combining radioactive imaging and NPs. First, we provide an overview of the NP platforms and their properties. This is followed by a look at methods for radiolabelling NPs with gamma-emitting radionuclides for use in single photon emission CT and planar scintigraphy. Next, utilization of positron-emitting radionuclides for positron emission tomography is considered. Finally, recent advances for multimodal nuclear imaging with NPs and efforts for clinical translation and ongoing trials are discussed.

Early loss of central visual acuity in glaucoma.

Central visual acuity is usually maintained until late in the course of glaucoma. Ten patients (5 men, 5 women) between the ages of 25 and 79 were found to have decreased visual acuity associated with central or centrocaecal scotomas early in their course. Five patients had chronic open-angle glucoma, three and pigmentary glaucoma, one and juvenile glaucoma, and one had Axenfeld's syndrome. A Marcus Gunn pupil was present in all six patients not on miotics. Most lost central acuity at pressures under 30 mmHg. Seven patients had vision of 20/200 or less. All with marked visual loss had a cup disc rate of .8 or greater. Other causes were carefully ruled out. Proposed mechanisms for the development of these central defects include either double Bjerrum scotomas which extend centrally or early papillomacular bundle involvement due to temporal cupping. This study demonstrates that decreased vision with associated central field loss can be a relatively early finding in glaucoma.