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Question 1

What are pathological processes

Answer 1

Pathological processes are the cause or the effect of a disruption of the normal physiological status. Associated with certain signals and anatomical structures.

Question 2

What are some methods of examining Pathological Processes on the outer surface of the body

Answer 2

Focused Physical Examination, Medical Thermology Imaging, Medical Transillumination Imaging

Question 3

what is Medical Thermology

Answer 3

imaging the 2D representation of the heat radiated from the human body

Question 4

what is Medical Transillumination Imaging

Answer 4

Transillumination imaging involves the shining of visible light or near-infrared radiation through a part of the body, and viewing or imaging the transmitted radiation (noninvasively)

Question 5

What are some invasive medical imaging procedures

Answer 5

Medical Endoscopy Imaging, Biopsy Examinations: Medical Light Microscopy Imaging and Medical Electron Microscopy Imaging

Question 6

What is Medical Endoscopy Imaging

Answer 6

uses an endoscope to examine the interior of a hollow organ or cavity of the body. Unlike many other medical imaging techniques, endoscopes are inserted directly into the organ. Can be simulated using CT-scans.

Question 7

define Hypertrophic

Answer 7

increase in the size of an organ or other part, resulting from enlargement of the individual cells.

Question 8

describe the anatomical planes

Answer 8

Coronal/Frontal Plane: Divides the body into anterior and posterior portions.
Sagittal/Lateral Plane: Divides the body into right and left sides. If using the midline as reference then called Median plane.
Trans-Axial/Transverse Plane: A horizontal plane dividing the body into upper and lower parts.

Question 9

how does Conventional X-ray Imaging capture anatomical features

Answer 9

X-Ray absorption is proportional to tissue density, therefore x-rays passed through the body will have a positive/negative outline of anatomical structures.

X-Ray photons are produced when electrons of high energy strike a heavy metal target (e.g. W), referred to as an X-ray Film. Contrast agents help increase the contrast between positive and negative.

Question 10

How does Digital X-ray Imaging differ from conventional methods

Answer 10

Uses X-Ray detectors instead of films. Detectors have a phosphor screen, which is excited by the X-Rays. CCDs (Charge-Coupled Device) or TFTs (thin-film transistor) convert light from phosphor to digital signal.

Question 11

how is Digital Mammography performed

Answer 11

breast is compressed and the x-ray is captured using a film plate.

Question 12

how is Digital Angiography performed

Answer 12

patient is injected with a radio-contrast agent, e.g. iodine, which absorbs x-rays. The dye may fill arteries, capillaries and veins.

Question 13

what is computer tomography

Answer 13

a computerized x-ray imaging procedure in which a narrow beam of x-rays is aimed at a patient and quickly rotated around the body in the gantry, producing signals that are processed by the machine’s computer to generate cross-sectional images or “slices” of the body.

Question 14

What anatomical plane does CT capture cross sections of

Answer 14

Transverse Plane

Question 15

What is the Hounsfield Attenuation Scale and what is its interpretation

Answer 15

A quantitative scale for describing radiodensity. Frequently used in CT scans. Based on water being 0 HU and air being -1000 HU. Very dense tissue can be up to 2000 HU. High-density structures are assigned brighter (whiter) colors.

Question 16

What is radiodensity

Answer 16

the relative inability of electromagnetic radiation, particularly X-rays, to pass through a particular material. Radiolucency indicates greater transparency or “transradiancy” to X-ray photons.

Question 17

What are the HUs for fat, soft tissue, and and bone

Answer 17

-100 HU,
+20 to +70 HU,
+400 to +2000 HU

Question 18

how does MRI work

Answer 18

The cylinder creates a strong magnetic field that causes the protons (hydrogen) in water to align with the magnetic field. External radio frequencies/pulses are then emitted, pushing the protons slightly out of alignment. Quickly, the protons will snap back to it’s original orientation, causing a radio signal (rotating magnetic field) to be emitted. This magnetic field is detected and used as the data.

Since the hydrogen in different tissues will realign at different speeds (depending on amount of hydrogen and type of tissue, particularly water and fat), the different structures of the body can be revealed.

Question 19

How are the radio frequencies from MRI analyzed to make images

Answer 19

filtered back projection reconstruction or Fourier analysis

Question 20

what are the benefits of MRI

Answer 20

non-invasive, captures fine details, does not require ionizing radiation such as x-rays. Flexible technique- contrast can be varied by varying how the image is acquired, such as adding additional magnetic fields or adjusting repetition time or echo time.

Question 21

What are T1 and T2 weighted images

Answer 21

differently constrasted MRI images based on different repetition time and echo time parameter settings.

T1: TR=small, TE=small, watery fluids are very dark, water-based tissues are mid-grey and fat-based tissues are very bright.

T2: TR=large, TE=large, fluids have the highest intensity, and water- and fat-based tissues are mid grey.

Question 22

In what contexts are T1 or T2 more suitable

Answer 22

T1 images are often known as “anatomy scans”, as they show most clearly the boundaries between different tissues.

T2 images are often thought of as “pathology” scans because collections of abnormal fluid are bright against the darker normal tissue.

Question 23

How does ultrasonic imaging work

Answer 23

It is based on the reflection of ultrasound at tissue interfaces.

Large, smooth surfaces in a body cause specular reflection, whereas rough surfaces and regions cause nonspecular reflection or diffuse scatter. fluid (black), soft tissue (grey), and bone (white).

Question 24

In what context is ultrasound useful

Answer 24

can be used to image muscle and soft tissue and is particularly useful for delineating the interfaces between solid and fluid-filled spaces.

However organs, such as the brain, located beneath bone cannot be imaged clearly.

Question 25

what are the benefits of ultrasound

Answer 25

real-time, non-invasive, portable, and inexpensive

Question 26

how does PET work

Answer 26

Patient is injected with a radiopharmaceutical, which is a tracer tagged with radioactive atoms/isotopes. These tracers emit positrons, which annihilate with surrounding electrons. This annihilation produces gamma rays, which are detected by the device.

Question 27

in what context are pet scans useful

Answer 27

when investigating physiological processes. It is particularly useful for detecting metabolic changes, since many malignant cells exhibit elevated glucose
metabolism (anaerobic glycolysis).

Most diseases are functional in nature and structural changes are secondary.

Question 28

what is microPET imaging

Answer 28

A miniature PET scanner for imaging mice

Question 29

What does SPECT stand for

Answer 29

Single Photon Emission Computed Tomography.

Question 30

How does SPECT work

Answer 30

patient inhales or is injected with a radionuclide (like PET and unlike CT). SPECT detects the gamma rays being directly emitted from the nuclei (unlike PET and like CT). Similar to CT, the camera system rotates around the patient.

Question 31

what is image registration

Answer 31

the process of aligning two or more images of the same scene.

This process involves designating one image as the reference image, also called the fixed image, and applying geometric transformations or local displacements to the other images so that they align with the reference. This is useful for combining functional images such as pet with anatomical images such as CT to gain a fuller understanding of the patient’s state.

Question 32

what are the different names for a pixel

Answer 32

image element, picture element, pel

Question 33

what is a k-bit image

Answer 33

for a grayscale image, each pixel/data structure is k-bits large, e.g. ints are 32 bits. meaning there are 2^k possible grayscale values for each pixel.

k is also referred to as the gray-level resolution, then the image is called a k gray level image e.g. 32 gray level image.

Question 34

What is image reconstruction

Answer 34

making an image from one-dimentsional projections into a two- (or higher) dimensional object

Question 35

What is the premise of the Algebraic Reconstruction Technique (ART)

Answer 35

the resultant reconstruction should match the measured projections (measured projection for a 1D line is a single value)

Question 36

describe steps in the ART system

Answer 36

(1) each value of the image begins at zero. (2) in each iteration, the new pixel value is calculated as (current pixel value + (measured projection value - the pixel values along the line of projection)/number of elements in that line). (3) This is performed for each pixel along the projection lines, then the next iteration begins. (4) Iterations occur until the final image’s projection (the sum of each pixel for that direction) matches the measured projections.

Question 37

what are some general challenges of medical imaging

Answer 37

Accessibility of the organ of interest, Variability of information, Physiological artifacts and interference, Energy limitations, Patient safety