Medical imaging technology has led to quicker diagnoses of conditions that, when caught early, can be treated. However, because such devices are large, they are impractical in the limited area of a space vehicle. An on-going NASA project to address the issue involves image fusion, where in-orbit ultrasounds would be combined with previously done Earth-bound scans that are more informative. Dr. Richard Boyle is the principal investigator.
NASA Tech Briefs:
What is image fusion?
Dr. Richard Boyle: In the simplest terms, image fusion is the combining of images of the same subject from different modalities, from CT scans to MRIs. This produces a coherent 3D image that has multi-dimensional information that should be superior to any of the constituent images alone. It adds function to the structure. You take an image and your X, Y, and Z coordinates, and anything beyond that becomes multi-dimensional. You can have different kinetics of the tissue. You can put those all together, and you have a very enhanced image where function is merged onto structure.
NTB: How is the image fusion process done?
Dr. Boyle: You start with acquiring the images. The subject is placed in an imaging device. You acquire the image, process that image, and then segment out different structures from each other. Then the process goes into registering the different types of images from each modality, and you start fusing them together. You then do the normal types of computer rendering to visualize the image. The next step, especially for the physician, would be to view make measurements, to see if something is abnormally large or small. This helps in interpreting any pathology that might exist.
NTB: What conditions could image fusion identify?
Dr. Boyle: Several. It could monitor for cancer. It could monitor the heart, whether it is enlarged or atrophied, or is experiencing any change in valvular structure. The kidneys could also pose potential problems, such as kidney stones. These are the types of problems one could monitor on a daily basis or once a week as needed to see if something is developing.
NTB: Are astronauts currently using image fusion?
Dr. Boyle: Not at the moment. The durations of current missions tend to be short. Once we get into long-duration flight, we would like to be able to provide some means of diagnostic aid. Ultrasound is the only thing available for in-orbit missions right now, primarily because of weight and its low power consumption. MRIs and CT scanners are extremely heavy and very power-hungry. Getting something that heavy and power-consuming into orbit is prohibitive.
NTB: Does the process have Earth-bound applications?
Dr. Boyle: It is being used now in various operating theaters. Primarily, doctors are mixing CT scans with MRIs, combining images of hard and soft tissue, with some of the functional studies from PET and SPECT scans. These can be used to monitor the tissue as a probe is introduced, either for bleeding in a particular area, or for injecting some enhancing agent that will attack or help cure different types of cancers. Image fusion is being used, and it is becoming more and more prevalent. The National Institutes of Health (NIH) now has a new institute that looks specifically at this line of study.