The higher the HU value the more dense an object is. Here are some important values to keep in mind on the HU scale. Adjusting windowing settings deals exclusively with these Hounsfield units and relates certain values to different shades of white, grey, and black. This is explained more in the sections below. These settings are quick to use and often times the most practical way to quickly change between window settings.
They also can help teach the concepts important to understanding what exactly window settings are. Below is an example of some standard window settings that can be found in a particular program utilized for reading CT scans.
The numbers seen in the figure above represent two different values. Let us quickly define what each of thee values represent. Window width: the window width refers to the number of different HU units that will be represented by different shades of gray. Window level: the window level refers to the midpoint HU value that is represented on the window setting. The lower the window level is set, the brighter the entire image will become. In this case, 7 mm "cuts" were used. Plain scans are done without infusion of any medication or agents.
IV infusion for contrast enhancement makes some lesions esp. Several different agents can be used. Omnipaque is used most often at our institution. It is given IV. Be sure renal function is OK via serum creatinine test before administration and be cautious if there is a tendency to congestive heart failure.
Scans after contrast infusion are usually labeled "enhanced" or "omnipaque" or "contrast. In the following example, the non-enhanced scan is shown above followed by the same view after contrast enhancement, the vascular nature of the lesion has led to a better view:. Transaxial plane is perpendicular to the axis and shows left and right, anterior and posterior as seen from below. It is the plane used most often for CT scans of the brain and for all of the images shown in this web site.
Coronal plane shows left and right, superior and inferior as seen from in front. It is often useful for CT scans of the sella and pituitary gland and paranasal sinus areas. Sagittal plane shows anterior to posterior, superior and inferior as seen from the side. Potts, Eds. Mosby, St. Louis, pp. Euclid Seeram. Computed Tomography.
ISBN: 3. Turner PJ, Holdsworth G. CT stroke window settings: an unfortunate misleading misnomer?. The British journal of radiology. CT mucosal window settings: a novel approach to evaluating early T-stage head and neck carcinoma. American journal of roentgenology. Related articles: Imaging technology. Promoted articles advertising. Loading more images Close Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys.
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