Begell House Inc.
Critical Reviews™ in Biomedical Engineering
CRB
0278-940X
36
5-6
2008
Segmentation of Images of Abdominal Organs
305-334
10.1615/CritRevBiomedEng.v36.i5-6.10
Jie
Wu
Departments of Computing and Software, , School of Biomedical Engineering; , McMaster University, Hamilton, Ontario, Canada
Markad
Kamath
Department of Medicine, McMaster University, 1200 Main St. West, Hamilton, Ontario L8N 3Z5, Canada
Michael D.
Noseworthy
Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, ON, Canada; Imaging Research Centre, St. Joseph's Healthcare Hamilton, 50 Charlton Ave. E., Hamilton, ON, Canada; Department of Electrical and Computer Engineering, McMaster University, 280 Main Street W., Hamilton, ON, Canada; School of Biomedical Engineering, McMaster University, Hamilton ON, Canada; Department of Radiology, McMaster University, 1280 Main St. W., Hamilton, ON, Canada
Colm
Boylan
Department of Radiology, McMaster University and St. Joseph's Health Care Hamilton
Skip
Poehlman
Departments of Computing and Software, McMaster University, Hamilton, Ontario, Canada
medical image processing
image segmentation
computed tomogra¬phy
magnetic resonance imaging
abdomen
organ recognition
pattern recognition
deformable model
Abdominal organ segmentation, which is, the delineation of organ areas in the abdomen, plays an important role in the process of radiological evaluation. Attempts to automate segmentation of abdominal organs will aid radiologists who are required to view thousands of images daily. This review outlines the current state-of-the-art semi-automated and automated methods used to segment abdominal organ regions from computed tomography (CT), magnetic resonance imaging (MEI), and ultrasound images. Segmentation methods generally fall into three categories: pixel based, region based and boundary tracing. While pixel-based methods classify each individual pixel, region-based methods identify regions with similar properties. Boundary tracing is accomplished by a model of the image boundary. This paper evaluates the effectiveness of the above algorithms with an emphasis on their advantages and disadvantages for abdominal organ segmentation. Several evaluation metrics that compare machine-based segmentation with that of an expert (radiologist) are identified and examined. Finally, features based on intensity as well as the texture of a small region around a pixel are explored. This review concludes with a discussion of possible future trends for abdominal organ segmentation.
A Review and Comparative Analysis of Recent Advancements in Fetal Monitoring Techniques
335-373
10.1615/CritRevBiomedEng.v36.i5-6.20
Anil Kumar
Tiwari
LNM Institute of Information Technology, Jaipur, India
Vijay
Chourasia
LNM Institute of Information Technology, Jaipur, India
fetal heart rate
fetal monitoring
fetal cardiotocography
fetal electrocardiography
fetal phonocardiography
fetal magnetocardiography
Over the past few years, various devices and techniques have been developed for electronic fetal monitoring (EFM), which is performed during pregnancy or continuously during labor to ensure normal delivery of a healthy baby. We reviewed and analyzed the performance of currently used EFM techniques with the goal of determining a noninvasive, cost-effective alternative for use in the home environment. This review includes research papers, publications, web sources, product manuals, interviews, formal discussions, and other available literature with the goal of providing a comprehensive comparative analysis of all available EFM techniques. We relate some of the insights gained from reviewing a large number of resources.
Transcranial Magnetic Stimulation: Physics, Electrophysiology, and Applications
375-412
10.1615/CritRevBiomedEng.v36.i5-6.30
Ali
Fatemi-Ardekani
Department of Medical Physics and Applied Radiation Sciences, McMaster University; Imaging Research Centre, Brain-Body Institute, St. Joseph's Healthcare, Hamilton, Ontario, Canada
transcranial magnetic stimulation
brain
neuron
electro-magnetism
electrophysiology
Transcranial magnetic stimulation (TMS) is a noninvasive technique used to stimulate the brain. This review will examine the fundamental principles of physics upon which magnetic stimulation is based, the design considerations of the TMS device, and hypotheses about its electrophysiological effects resulting in neuromodulation. TMS is valuable in neurophysiology research and has significant therapeutic potential in clinical neurology and psychiatry. While TMS can modify neuronal currents in the brain, its underlying mechanism remains unknown. Salient applications are included and some suggestions are outlined for future development of magnetic stimulators that could lead to more effective neuronal stimulation and therefore better therapeutic and diagnostic applications.
What Came First: Fully Functional or Metabolically Mature Liver?
413-439
10.1615/CritRevBiomedEng.v36.i5-6.40
Rene
Schloss
Department of Biomedical Engineering, Rutgers University, Piscataway, NJ, USA
Martin
Yarmush
Center For Engineering in Medicine, Shriners Hospital for Children, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts; and Department of Biomedical Engineering, Rutgers University, Piscataway, NJ, USA
embryonic stem cells
metabolic engineering
hepatocytes
oligodendrocytes
cellular differentiation
Hepatocytes, which constitute about 70% of the liver cell population, perform complex metabolic functions such as plasma protein synthesis and transport, xenobiotic metabolism, glucose homeostasis, urea synthesis, and ketogenesis. The process of liver development is marked by distinct changes in mitochondrial mass, activity, and function, especially during the transition from the fetal to the adult phenotype. The identification of the biochemical mechanisms implicated in hepatic development in vitro using embryonic stem cells is critical because it can unravel the relationship between metabolic changes and cell-specific functional differentiation. Moreover, embryonic stem cell differentiation into hepatocytes can provide an unlimited source of cells for clinical applications in liver transplantation for cirrhosis and fulminant hepatic failure. The "chicken or the egg" problem of whether functional maturation precedes or follows metabolic maturation remains unanswered, but it might simply be that the two processes develop in a complex integrated mode for metabolic and functional homeostasis. The identification of the regulation of complex developments in liver organogenesis can provide interventions to improve the efficiency of hepatic differentiation and a better understanding of the developmental process. Finally, this reasoning can be extended to various cell specific differentiation systems, including the cardiac, pancreatic, and neuronal lineages.
Hybrid Superporous Scaffolds: An Application for Cornea Tissue Engineering
441-471
10.1615/CritRevBiomedEng.v36.i5-6.50
Arpita
Kadakia
Department of Bioengineering, University of Illinois, Chicago, IL, USA
Vandana
Keskar
Department of Biopharmacuetical Sciences, University of Illinois, Chicago, IL, USA
Igor A.
Titushkin
Bioengineering Department, University of Illinois, Chicago, USA
Ali
Djalilian
Department of Ophthalmology and Visual Science, University of Illinois, Chicago, IL, USA
Richard A.
Gemeinhart
Department of Bioengineering, and Department of Biopharmacuetical Sciences, University of Illinois, Chicago, IL, USA
Michael
Cho
Department of Bioengineering, University of Illinois, Chicago, IL, USA
keratoprosthesis
artificial cornea
3-D hybrid scaffold
superporous hydrogel
collagen
polyethylene glycol diacrylate
Engineering a cell-based keratoprosthesis often requires a struggle between two essential parameters: natural 3-D biological adhesion and mechanical strength. A novel hybrid scaffold of natural and synthetic materials was engineered to achieve both cell adhesion and implantable strength. This scaffold was characterized in terms of cell adhesion, cell migration, swelling, and strength. While the study was focused on engineering a biointegrable prosthetic skirt, a clear central core with an appropriate refractive index and light transmission was also incorporated into the design for potential functionality. The hybrid scaffold was tested in rat corneas. This uniquely designed scaffold was well tolerated and encouraged host cell migration into the implant. The hybrid superporous design also enhanced cell adhesion and retention in a superporous scaffold without altering the bulk mechanical properties of the hydrogel.