Talk:Computed Tomography

2010

Rapid Three-Dimensional Phenotyping of Cardiovascular Development in Mouse Embryos by Micro-CT with Iodine Staining

Degenhardt K, Wright AC, Horng D, Padmanabhan A, Epstein JA. Circ Cardiovasc Imaging. 2010 Feb 27. PMID: 20190279

2009

MicroCT for comparative morphology: simple staining methods allow high-contrast 3D imaging of diverse non-mineralized animal tissues

BMC Physiol. 2009 Jun 22;9:11.

Metscher BD.

Department of Theoretical Biology, Gerd Müller, University of Vienna, Althanstrasse 14, 1090 Austria. brian.metscher@univie.ac.at Abstract BACKGROUND: Comparative, functional, and developmental studies of animal morphology require accurate visualization of three-dimensional structures, but few widely applicable methods exist for non-destructive whole-volume imaging of animal tissues. Quantitative studies in particular require accurately aligned and calibrated volume images of animal structures. X-ray microtomography (microCT) has the potential to produce quantitative 3D images of small biological samples, but its widespread use for non-mineralized tissues has been limited by the low x-ray contrast of soft tissues. Although osmium staining and a few other techniques have been used for contrast enhancement, generally useful methods for microCT imaging for comparative morphology are still lacking.

RESULTS: Several very simple and versatile staining methods are presented for microCT imaging of animal soft tissues, along with advice on tissue fixation and sample preparation. The stains, based on inorganic iodine and phosphotungstic acid, are easier to handle and much less toxic than osmium, and they produce high-contrast x-ray images of a wide variety of soft tissues. The breadth of possible applications is illustrated with a few microCT images of model and non-model animals, including volume and section images of vertebrates, embryos, insects, and other invertebrates. Each image dataset contains x-ray absorbance values for every point in the imaged volume, and objects as small as individual muscle fibers and single blood cells can be resolved in their original locations and orientations within the sample.

CONCLUSION: With very simple contrast staining, microCT imaging can produce quantitative, high-resolution, high-contrast volume images of animal soft tissues, without destroying the specimens and with possibilities of combining with other preparation and imaging methods. Such images are expected to be useful in comparative, developmental, functional, and quantitative studies of morphology.

PMID: 19545439 http://www.ncbi.nlm.nih.gov/pubmed/19545439

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2717911

http://www.biomedcentral.com/1472-6793/9/11

2008

Guidelines for computed tomography and magnetic resonance imaging use during pregnancy and lactation

Obstet Gynecol. 2008 Aug;112(2 Pt 1):333-40.

Chen MM, Coakley FV, Kaimal A, Laros RK Jr.

Department of Radiology, University of California, San Francisco, School of Medicine, San Francisco, California, USA. Abstract There has been a substantial increase in the use of computed tomography (CT) and magnetic resonance imaging (MRI) in pregnancy and lactation. Among some physicians and patients, however, there are misperceptions regarding risks, safety, and appropriate use of these modalities in pregnancy. We have developed a set of evidence-based guidelines for the use of CT, MRI, and contrast media during pregnancy for selected indications including suspected acute appendicitis, pulmonary embolism, renal colic, trauma, and cephalopelvic disproportion. Ultrasonography is the initial modality of choice for suspected appendicitis, but if the ultrasound examination is negative, MRI or CT can be obtained. Computed tomography should be the initial diagnostic imaging modality for suspected pulmonary embolism. Ultrasonography should be the initial study of choice for suspected renal colic. Ultrasonography can be the initial imaging evaluation for trauma, but CT should be performed if serious injury is suspected. Pelvimetry now is used rarely for suspected cephalopelvic disproportion, but when required, low-dose CT pelvimetry can be performed with minimal risk. Although iodinated contrast seems safe to use in pregnancy, intravenous gadolinium is contraindicated and should be used only when absolutely essential. It seems to be safe to continue breast-feeding immediately after receiving iodinated contrast or gadolinium. Although teratogenesis is not a major concern after exposure to prenatal diagnostic radiation, carcinogenesis is a potential risk. When used appropriately, CT and MRI can be valuable tools in imaging pregnant and lactating women; risks and benefits always should be considered and discussed with patients.

PMID: 18669732

From Wiki

Computed Tomography (CT) imaging works through X-rays that are emitted from a focused radiation source that is rotated around the test subject placed in the middle of the CT scanner.[1] The X-ray is attenuated at different rates depending on the density of tissue it is passing through, and is then picked up by sensors on the opposite end of the CT scanner from the emission source. In contrast to traditional 2D X-ray, since the emission source in a CT scanner is rotated around the animal, a series of 2D images can then be combined into 3D structures by the computer.