MRI

Question 1

Perivaskulär

Answer 1

um ein Gefäß herum” bzw. “in der Nähe eines Gefäßes”

Question 2

Isotrope Voxel

Answer 2

haben in allen drei Raumrichtungen dieselbe räumliche Auflösung

Question 3

Voxel

Answer 3

Gitterpunkt (Bildpunkt, Datenelement) in einem dreidimensionalen Gitter.
Dies entspricht einem Pixel in einem 2D-Bild, einer Rastergrafik

Question 4

Sub-sampling

Answer 4

a method to downsample feature maps as we move along the network
Average pooling is a variant of sub-sampling where the average of pixels that fall within the receptive field of a unit within a sub-sampling layer is taken as the output

Question 5

lesion

Answer 5

a region in an organ or tissue which has suffered damage through injury or disease, such as a wound, ulcer, abscess, or tumour.

Läsion, Verletzung, Wunde

Question 6

hepatic

Answer 6

relating to the liver.

Question 7

anisotropic

Answer 7

having a physical property which has a different value when measured in different directions. An example is wood, which is stronger along the grain than across it.

Question 8

magnetic field

Answer 8

is a vector field that describes the magnetic influence on moving electric charges, electric currents and magnetized materials

Question 9

CSF

Answer 9

cerebrospinal fluid is a clear, colorless body fluid found in the brain and spinal cord

Question 10

lattice

Answer 10

The name spin-lattice relaxation refers to the process in which the spins give the energy they obtained from the RF pulse back to the surrounding lattice, thereby restoring their equilibrium state

Question 11

phase coherence

Answer 11

A term describing the degree to which precessing nuclear spins are synchronous

http://mriquestions.com/phase-coherence.html

Question 12

transversal slice

Answer 12

A tomographic imaging plane, parallel to the ground, perpendicular (rotated 90°) to the long axis of the human body; the axial plane separates the superior from the inferior part (the head from the feet).
Also called transaxial, transversal, transverse plane.

Question 13

sagittal slice

Answer 13

A plane, slice or section of the body cutting from front to back, and continued down through the body in the same direction, dividing it into two parts.

Question 14

coronal slice

Answer 14

A tomographic imaging plane, perpendicular to the ground, the coronal plane separates the anterior from the posterior part (the front from the back)

Question 15

bandwidth

Answer 15

Bandwidth is the difference between the upper and lower frequencies in a continuous band of frequencies. A frequency band is an interval in the frequency domain, delimited by a lower frequency and an upper frequency. The frequency domain refers to the analysis of mathematical functions or signals with respect to frequency, rather than time. A frequency-domain graph shows how much of the signal lies within each given frequency band over a range of frequencies.

or analog bandwidth, frequency bandwidth, or radio bandwidth, a measure of the width of a frequency range

Question 16

resonance

Answer 16

only when the RF pulse and the protons have the same frequency, can protons pick up some energy from the radio wave -> a phenomenon called resonance

resonance: the transferral of energy from radio wave to protons

Question 17

gradient field

Answer 17

tbd

is produced by the so-called gradient coils

Question 18

gradient coils

Answer 18

gradient coils are used to systematically vary the magnetic field by producing additional linear electromagnetic fields,
thus making slice selection and spatial information possible

As we have three dimensions in space, there are three sets of gradient coils

Question 19

radio wave

Answer 19

radio wave describes an electromagnetic wave that is in the frequency range of the waves which you receive in your radio

Question 20

radio frequency (RF) pulse

Answer 20

The purpose of this RF pulse is to disturb the protons, which are peacefully precessing in alignment with the external magnetic field

Energy exchange is possible when protons and the radiofrequency pulse have the same frequency

Question 21

parametric map

Answer 21

tbd

Question 22

DW-MR

Answer 22

Diffusion-weighted magnetic resonance

Question 23

DCE-MR

Answer 23

Dynamic contrast enhanced magnetic resonance

Question 24

elastography (MRE)

Answer 24

Elastography is a medical imaging modality that maps the elastic properties and stiffness of soft tissue. The main idea is that whether the tissue is hard or soft will give diagnostic information about the presence or status of disease. For example, cancerous tumours will often be harder than the surrounding tissue, and diseased livers are stiffer than healthy ones

Question 25

relaxometry

Answer 25

relaxometry is measurement of relaxation times from MR images. T1, T2 and T2* can be estimated using the appropriate pulse sequence and parameters. T2 relaxometry has found useful in quantitating signal changes on T2-weighted images as in evaluating mesial temporal sclerosis.

Question 26

steatosis

Answer 26

steatosis, also called fatty change, is abnormal retention of fat (lipids) within a cell or organ. Steatosis most often affects the liver – the primary organ of lipid metabolism – where the condition is commonly referred to as fatty liver disease

Question 27

extracellular volume (ECV)

Answer 27

the body water outside cells

Question 28

biomarker

Answer 28

is a biological measure of a biological state. By definition, a biomarker is “a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes or pharmacological responses to a therapeutic intervention.”

Biomarkers are the measures used to perform a clinical assessment such as blood pressure or cholesterol level and are used to monitor and predict health states in individuals or across populations so that appropriate therapeutic intervention can be planned.

Biomarkers may be used alone or in combination to assess the health or disease state of an individual.

Question 29

MR spectroscopy

Answer 29

The technique of magnetic resonance spectroscopy allows tissue to be interrogated for the presence and concentration of various metabolites.

it is fair to say that MRS often does not add a great deal to an overall MR study but does increase specificity, and may help in improving our ability to predict histological grade

Question 30

the liver parenchyma

Answer 30

The liver parenchyma is the functional tissue of the organ made up of around 80% of the liver volume as hepatocytes. The other main type of liver cells are non-parenchymal.
Non-parenchymal cells constitute 40% of the total number of liver cells but only 6.5% of its volume

Question 31

DICOM

Answer 31

DICOM = Digital Imaging and CommunicaDons in Medicine

the international standard for handling, storing, printing and transmitting medical imaging data

Clinical imaging equipment (CT scanners, MR scanners, X-Ray and ultrasound machines) generate DICOM files

Question 32

nrrd

Answer 32

Nrrd (“nearly raw raster data”) is a library and file format for the representation and processing of n-dimensional raster data. It is intended to support scientific visualization and image processing applications.

NRRD is a file format for storing and visualizing medical image data. Its main benefit over DICOM, the standard file format for medical imaging, is that NRRD files are anonymized and contain no sensitive patient information. Furthermore NRRD files can store a medical scan in a single file, whereas DICOM data sets are usually comprised of a directory or directories that contain dozens if not hundreds of individual files. NRRD is thus a good file for transferring medical scan data while protecting patient privacy.

https://www.embodi3d.com/blogs/entry/341-how-to-create-an-nrrd-file-from-a-dicom-medical-imaging-data-set/

Question 33

registration

Answer 33

Registration algorithms bring different image datasets into spatial alignment, in order to achieve anatomical agreement.

Question 34

slice thickness

Answer 34

Voxel size is related to both the pixel size and slice thickness.

A voxel is the volume element, defined in 3D space. Its dimensions are given by the pixel, together with the thickness of the slice (the measurement along the third axis).
Slice thicknesses in clinical MRI vary from a maximum near 5 mm, achieved using 2D multislice imaging, to submillimeter, achieved with 3D scan techniques.

Question 35

field of view (FOV)

Answer 35

Defined as the size of the two or three dimensional spatial encoding area of the image.
Usually defined in units of mm².
The FOV is the square image area that contains the object of interest to be measured.
The smaller the FOV, the higher the resolution and the smaller the voxel size but the lower the measured signal.

Question 36

bias field correction

Answer 36

The bias field usually appears due
to improper image acquisition from the scanner, and influences machine learning algorithms that
perform classification and segmentation using pixel intensities. It is, therefore, important to either
remove the bias field artifacts from sample images or incorporate this artifact into the model before
training on these images

• the bias field accounts for intensity inhomogeneity
• Bias correction (BC) is utilized in the level set formulation to suppress the influence of intensity inhomogeneity

Question 37

DW-MRI

Answer 37

diffusion-weighted MRI

is the use of specific MRI sequences as well as software that generates images from the resulting data that uses the diffusion of water molecules to generate contrast in MR images.

Question 38

contrast inversion

Answer 38

Inversion of contrast changes the positive radiographic image into a negative one. For example, this enhancement changes the radiopaque white appearance of the bone into the black one and the radiolucent black appearance of the air into the white one. This altered image may be useful in some clinical situations due to its effect on observer perception. There are numerous studies about the effect of contrast inversion on radiographic diagnostic and measurement accuracy of dental problems such as caries, fractures, interproximal bone loss, and periapical lesions

Question 39

gamma correction

Answer 39

• Gamma correction controls the overall brightness of an image.
• Gamma correction is a non-linear operation used in histogram adjustment
  https: //en.wikipedia.org/wiki/Gamma_correction

gamma is what translates between our eye’s light sensitivity and that of the camera.
https://www.cambridgeincolour.com/tutorials/gamma-correction.htm

Question 40

MRA

Answer 40

Magnetic resonance angiography–also called a magnetic resonance angiogram or MRA–is a type of MRI that looks specifically at the body’s blood vessels