CT Flashcards
What is PACs
Picture archiving and communication system (PACS) is a medical imaging technology used primarily in healthcare organizations to securely store and digitally transmit electronic images and clinically-relevant reports.
What is curved planar reformation ?
involves tracing a structure, such as a blood vessel, ureter or intestine, and generating a planar (two-dimensional) image that transects the structure along its short axis. This is very useful in CT/MR angiography (CTA).
What is MIP?
Maximum Intensity Projection (MIP) consists of projecting the voxel with the highest attenuation value on every view throughout the volume onto a 2D image 1.
Such an algorithm is rather simple: for each XY coordinate, only the pixel with the highest Hounsfield number along the Z-axis is represented so that in a single bidimensional image all dense structures in a given volume are observed. For example, it is possible to find all the hyperdense structures in a volume, independently of their position 2.
This method tends to display bone and contrast material-filled structures preferentially, and other lower-attenuation structures are not well visualised 2. The primary clinical application of MIP is to improve the detection of pulmonary nodules and assess their perfusion. MIP also helps characterise the distribution of small nodules. In addition, MIP sections of variable thickness are excellent for assessing the size and location of vessels, including the pulmonary arteries and veins 1.
What is MinIP ?
Minimum intensity projection (MinIP) is a data visualisation method that enables detection of low-density structures in a given volume. The algorithm uses all the data in a volume of interest to generate a single bidimensional image, in other words, it consists of projecting the voxel with the lowest attenuation value on every view throughout the volume onto a 2D image 1,3.
The MinIP algorithm is almost identical to the MIP algorithm but, in the case of MinIP, for each XY coordinate, only the lowest Hounsfield value along the Z axis is represented. In this way, only the most hypodense structures of the volume are represented 1.
So it is the optimal tool for the detection, localisation, and quantification of ground-glass opacity, mosaic attenuation, traction bronchiectasis, cystic lung disease and linear attenuation patterns on chest CT 3,4.
The MinIP algorithm is particularly useful for analysing the bile tree and pancreatic duct, which are hypodense compared to surrounding tissue, especially in the pancreatic and portal phase of contrast agent administration 2.
What is 3D MPR?
Multiplanar reformation or reconstruction (MPR) involves the process of converting data from an imaging modality acquired in a certain plane, usually axial, into another plane 1. It is most commonly performed with thin-slice data from volumetric CT in the axial plane, but it may be accomplished with scanning in any plane and whichever modality capable of cross-sectional imaging, including magnetic resonance imaging (MRI), PET and SPECT.
What is 3D volume rendering
Volume rendering is a type of data visualisation technique which creates a three-dimensional representation of data. CT and MRI data are frequently visualised with volume rendering in addition to other reconstructions and slices. This technique can also be applied to tomosynthesis data. Volume rendering is primarily done for better visualisation of human anatomy, surgical treatment planning as well as in medical teaching
What is metadata?
Metadata is the data that describes other data. It helps answer the question “what is this data about?” High quality metadata provides helpful context about the data’s creation, quality, and uses and is key to improving data discovery.
What are the common window widths and levels for the different scans used in CT?
UHWI:
Brain - WL 40 WW 100 (from -10 to 90)
Brain - bone window - WL 400 WW 2500 ( -850 to 1,650)
C spine WL 500 WW 1600 (-300 to -1300) vs soft tissue WL 60 WW 300 (-90 to 210)
CTPA soft tissue WL 40 WW 40 (-160 to 240)
CTPA - (any lung) lung WL -600 WW 1600 (-1400 to 200)
Soft tissue - Chest & abdomen - WL 60 WW 360 (-120 to 240)
Radiopaedia: image attached
