Simulteneous picomolar sensitivity MRI and photoacoustic imaging

Multimodality imaging studies have gained widespread importance because they allow limitations of individual modalities to be overcome while capitalizing on the strengths of the modalities that were combined. A new combination of imaging modalities has been achieved by Bouchard et al. (PNAS, March 2009), where they built a system and have performed simultaneous picomolar sensitivity MRI and photoacoustic imaging of cobalt nanoparticles. This system also has the capability of performing photothermal imaging. The research group's application for multimodality imaging is novel and presents great promise.

Critical appraisal of one's own work

Scientists and clinicians, because of the somewhat specialized area of their work and because the field of medicine is so competitive, may be tempted to overlook the weaknesses of their own work while only highlighting it's strength. This post highlights a recent article (Young et al., Nat Clin Pract Gastroenterol Hepatol, 2009) which presents a 10-step guide to critical appraisal of clinical data. In our opinion, these steps could be followed for a just criticism for one's own work.

The travelling-wave MRI problem

One of the major limitations in performing MRI imaging with high field strengths (3T or 7T) in humans has been than the resultant magnetic field tends to be spatially inhomogeneous and reconstructed images tend to have areas where signal is lost. This post highlights a recent paper ( Brunner et al., Nature, 2009 ) which shows how these problems can effectively be solved using a remote antenna. Very influential work!

High spatial and temoporal resolution in magnetic resonance

Scientists developing instrumentation and techniques for in vivo imaging desperately try for both high spatial resolution and high temporal resolution for their devices. The former allows them to visualize small or weak objects more clearly and helps in quantification. The latter allows for the detailed study of dynamic processes. This post highlights two recent articles: Degen et al, PNAS, Jan 2009 and Weizenecker et al Phys. Med. Bio, 2009. The first article shows a technique of obtaining nanometer level spatial resolution for MRI. The second article shows first in vivo imaging results using real time magnetic particle imaging. Both articles are well written and demonstrate high grade science.

Proton therapy for cancer treatment

The technique of proton-beam therapy has undergone re-birth over the past decade and should soon be a part of clinical practice for oncology. This post is about a recent Vision 20/20 paper by Smith, Medical Physics, Feb 2009, that overviews this technology and advocates pRoton therapy over pHoton therapy. The potential of this technology is clear and the future is very promising. I know this is not medical imaging, but it influences the field greatly.

Brain imaging using brain power

Brain imaging studies, especially those based on behavioral or social aspects, always get a lot of publicity. Most top journals including Nature, Science, PNAS, etc. often highlight works in this research area. It is quite easy to get side-tracked by some of these works. This is partly because so little is known that any interpretation can easily sell without enough proof. There, however, are researchers who strictly follow evidence-based medicine. The studies these researchers conduct take a lot longer to finish and it means less papers. However, in the long run, the latter have a lasting impact on the field. This post highlights a paper by researchers from MIT and UCSD (Vul et al., Perspectives on Psychological Science, 2009, in press), where they have critically examined metrics that are used to describe brain imaging studies in social neuroscience experiments. This work is extremely interesting and presents a lot of food for thought.

Rebinning of time-of-flight Positron Emission Tomography data to no-time-of-flight

Positron Emission Tomography scanners that are capable of measuring time-of-flight (TOF) have undergone several iterations over the past 30 years. However, while there is little doubt that, theoretically, these scanners should yield improved spatial resolution, the amount of data measured are overwhelming. Thus, taking full advantage of the additional timing parameter has becomes difficult. This post highlights work done to address this issue at Dr Richard M. Leahy's laboratory at USC (Cho et al., Phys Med Biol. Feb 2009), where the Fourier re-binning technique has been used for dimensionality reduction of the TOF data to convert it to non-TOF data. This work has been short-listed in Institute of Physics' selected papers. Very promising work, to say the least.

pH activated fluorescent probes

Fluorescent probes activated by the environment they are in show tremendous promise for molecular imaging because of their improved specificity, and in turn, reduced autofluorescence from the background. This post highlights a paper from a Japanese group (Urano et al., Nature Medicine, Dec 2008) that shows imaging results of a fluorescent agent that, "is activated after cellular internalization by sensing the pH change in the lysosome." These probes potentially should be useful in optical fluorescence tomography, where small lesions can be missed because of autofluorescence effects.

Combined optical imaging and mammography

Multimodality imaging has become the buzzword this decade as many medical systems that combine two or more imaging modalities have become commercially available. My first post is about a paper from Dr David Boas's research group at MGH (Fang et al, IEEE Trans Med Imaging, Jan 2009). This paper shows preliminary data and reconstructed images obtained from healthy subjects using a system that combines diffuse optical breast imaging with X-ray mammography. The analysis of pressure from breast compression as it affects blood re-distribution is extremely interesting. Highly recommended by me!