This article is a US Government work and, as such, is in the public domain in the United States of America.
Biomedical Imaging: 2001 and Beyond†
Article first published online: 30 MAR 2001
Copyright © 2001 Wiley-Liss, Inc.
The Anatomical Record
Special Issue: Advances in Biomedical Imaging
Volume 265, Issue 2, pages 35–36, 15 April 2001
How to Cite
Lester, D. S. and Olds, J. L. (2001), Biomedical Imaging: 2001 and Beyond. Anat. Rec., 265: 35–36. doi: 10.1002/ar.1056
- Issue published online: 26 DEC 2002
- Article first published online: 30 MAR 2001
Biomedical imaging was primarily developed for clinical applications, in particular diagnosis of disease states. The initial imaging approach was the X-ray. A number of innovative methodologies emerged in the 1970s, including Magnetic Resonance Imaging (MRI), Positron Emission Tomography (PET), and Computer Assisted Tomography scans (CT scans). Subsequent to the advent of the latter approach, CT scanning had an enormous impact on diagnostic medicine in the 1970s and 1980s, which was further advanced by the tremendous contributions of MRI in the 1990s. In 1998, over seven million MRI scans were performed on patients, compared to virtually none before the mid-1980s (Holzman, 2000). More recently, PET scanning for diagnosis and determination of certain types of cancer has been approved for health insurance reimbursement. Thus, much of the development of imaging technology has been driven by diagnostic medicine. This is not the case for other technologies in biomedical research, where the early stages of development are employed using animals or even cells, often the raison d'être for these strategies. This feature of biomedical imaging demonstrates the ultimate strength of the new imaging technologies, in that the same methodology is applicable to human and animal research.
In recent years, there has been a recapitulation of human biomedical imaging approaches applied to animal research. The revisiting of the more basic applications has not been trivial, as the most advanced imaging technologies have not had the necessary characteristics in order to provide useful animal data. Much of the limitation relates to the issue of spatial resolution. While imaging technology provides sufficient detail at the human level (≈2 mm for MRI, ≈3 mm for PET), this is considered inadequate for practical imaging in the rat, mouse and even rabbit. In addition, considerable scan time was required in the past in order to generate suitable images of the tissue of interest. While humans can be told not to move or asked to be positioned in certain ways, this has not been practical or applicable to animals. Significant restraints have been necessary and sometimes anesthesia required in order to maintain the animal in the appropriate repose. Such limitations of intact animal imaging have previously resulted in poor temporal resolution.
Before planning an imaging experiment, it is necessary to determine the nature of the data required. There are numerous different imaging modalities and the capabilities of some of the more commonly used technologies are listed in Table 1
|Data Type||Imaging Modality|
The most powerful characteristic of imaging is that it can be performed in a noninvasive manner. Thus, the sample of interest is kept intact (for all intents and purposes). Considering this feature, all imaging can be considered to be relevant to anatomy, whether at the level of the intact organism, the tissue, or the cell. Imaging has the most significant advantage in that it provides information as to the location of the region of interest while maintaining the spatial dimensions in relation to the entire entity being analyzed. Whether it is a functional, pharmacologic, or genetic change, the data always provide the spatial (and often temporal) location relevant to the entire entity. While in past centuries it has always been necessary to dissect cadavers or animals in order to determine anatomy, imaging provides the luxury of making such studies on a living specimen. Thus, imaging provides living anatomy.
In a sense, imaging has created a new role for the anatomist, i.e., the anatomist must develop multidisciplinary skills in order to interact with experts of different disciplines. The “new” anatomist needs to have an understanding of the significance of changes in blood flow in the brain in order to be able to evaluate identified changes in a specific brain region upon some functional challenge. Because of this evolution, it is vital that anatomy departments and anatomists take an active role in any education programs that involve imaging. The American Association of Anatomists has been a leader in this area by supporting imaging conferences and providing “state of the art” symposia at the yearly FASEB conferences.
The development of imaging technologies has evolved in two distinct directions; 1.) extensions of existing clinical approaches, and 2.) development of animal and cellular imaging systems. This special issue of The New Anatomist presents five articles that highlight examples of both of these directions. There is insufficient space to include all of the different imaging modalities that are available; however, we plan to bring in future issues examples of other studies highlighting applications to issues relating to anatomy.
In this issue, we present contributions showing different applications of imaging as well as the use of different imaging modalities. Four of the articles highlight the use of different MRI applications, including MRI, fMRI, MRSI, and microMRI. The reason for the concentration of MRI articles is that this technique is the most appropriate for obtaining anatomical data. It is capable of capturing anatomical data in the form of structure and/or function. MRI has numerous advantages, including ability to noninvasively analyze human and animal specimens, short scan times, numerous scanning sequences, and a variety of intrinsic signals.
Animal studies are presented in the contributions of Beckmann et al. (2001) and Borah et al. (2001), while the reports of Ross and Bluml (2001) and Zeineh et al. (2001) concentrate on human analyses. All of these studies concentrate on analyzing a variety of intrinsic signals varying from the traditional proton spectra (MRI) to complex signals such as metabolites of the major energy pathways (MRSI). The major disadvantage of MRI is its sensitivity, which is highlighted in the review article by Ross and Bluml (2001), where the spatial resolution is not optimal. However, considering the nature of the data and the ability to compare a number of metabolites in the same region, the spatial resolution is not as critical as the spectral data that provide the necessary information in order to be able to distinguish diseased states. It also provides regional localization of these changes.
Functional MRI, which is less sensitive than proton MRI, has been exquisitely used in the contribution of Zeineh et al. (2001) to provide mapping of hippocampal functioning in memory tasks. The tutorial by Beckmann et al. (2001) demonstrates the pragmatic approach necessary in the pharmaceutical industry in order to develop animal models and paradigms for examining drug efficacy, which is critical in providing direction for clinical trial studies. This approach is gaining considerable recognition in the pharmaceutical industry. This use of animal imaging also promises to significantly reduce the number of animals that are necessary for such studies, while providing significantly better information.
The study by Borah et al. (2001) demonstrates an excellent study on how imaging approaches can be used to solve a specific question that is related to the diagnosis of disease and development of appropriate therapies. The combined use of microMRI and microCT conclusively demonstrates that these imaging modalities provide more concise and informative data on progressive bone disease than existing histological procedures.
The final contribution by Toga and Thompson (2001) relates to a very important issue in modern day biology in general, the issue of informatics. As for many of the new screening techniques, imaging provides massive amounts of information. The process of characterizing and categorizing this information and then synthesizing it into some practical contribution is very complex. Toga and coworkers (2001) have been leaders in this research approach for many years. Their contribution provides an insight into brain structure and function that is possible due to the advances in imaging and computing software and hardware.
This issue of The New Anatomist provides a spectator's seat for some of the “cutting edge” imaging applications. The emphasis has been on the application of the technologies, not the technologies themselves. The authors are not the researchers that have developed the technology, but rather investigators with important scientific questions that have applied appropriate technologies in order to obtain the answer they are seeking. These authors were invited to contribute based on their respective abilities to answer complex biomedical research questions. With the continued work of such authors and others to be featured in future issues of The New Anatomist, the sustained significant impact of biomedical imaging on public health and safety is guaranteed.
- 2001. From anatomy to the target: Contributions of magnetic resonance imaging to pre-clinical pharmaceutical research. Anat Rec (New Anat) 261: 85-100. , , , , .
- 2001. Three-dimensional microimaging (MRμI and μCT), finite element modeling, and rapid prototyping provide unique insights into bone architecture. Anat Rec (New Anat) 261: 101-110. , , , , , , , , .
- 2000. Magnetic resonance imagining: from atomic physics to visualization, understanding and treatment of brain disorders. In: Breakthroughs in Bioscience. FASEB Office of Public Affairs Online Publications. http://www.faseb.org/opar/mri/; PDF available at www.faseb.org/opar/mri/mri.pdf. .
- 2001. Magnetic resonance spectroscopy of the human brain. Anat Rec (New Anat) 261: 54-84. , .
- 2001. Maps of the brain. Anat Rec (New Anat) 261: 37-53. , .
- 2001. Unfolding the human hippocampus with high resolution structural and functional MRI. Anat Rec (New Anat) 261: 111-120. , , , .