BME 311: Lecture 1

bioimaging

• any imaging of biological tissue-living or not (CT, MRI, PET, ultrasound)

• also non-human organisms

• can be invasive, including excised tissue/biopsy

• can be used purely for research

• can be very high resolution - light or electron microscopy

different purposes/different techniques

• detection/screening-lesion (cancerous)?

• diagnosis-invasive or benign?

• staging-how bad, metastasized?

• monitoring of treatment-shrinking?

• surveillance-returned?

• research-understand structure/function

organs

organization of several different kinds of tissues arranged together to perform a specific function

medical imaging of human body requires some form of energy

• capable of penetrating tissue

• all imaging techniques (except nuclear imaging) require energy-tissue interaction

• visible light has limited penetration

electromagnetic (EM) radiation is used for

• nuclear imaging (ionizing)

• x ray imaging (ionizing)

• magnetic resonance imaging (non-ionizing)

• optical/infrared imaging (non-ionizing)

• NOT ultrasound

radiography

2D imaging with x-rays

computer tomography (CT)

3D imaging with x-rays

nuclear imaging (PET, SPECT)

mostly 3D imaging with gamma-rays

magnetic resonance imaging (MRI)

3D imaging with radio-waves

ultrasound

mostly 2D imaging with sound waves

morphology in biology

outward appearance (shape, structure, color) of an organism and its component parts

microscopic vs macroscopic

micro-cells macro-tissues, organs, systems

superior or cranial

toward the head end of the body

upper (the arm is a superior extremity)

inferior or caudal (tail)

away from the head

lower (the leg is an inferior extremity)

anterior or ventral

front (knee cap is located on the anterior side of the leg)

in human (bipedal) brain, ventral has different meaning:towards body

posterior or dorsal

back (spine located on the posterior of the body)

in human (bipedal) brain, dorsal has different meaning:towards top of head

medial

toward the midline of the body or body part

(middle toe is located at the medial part of the foot)

lateral

away from the midline of the body or body part

(little toe is located at a lateral part of the foot)

proximal

toward or nearest the trunk or the point of origin of a part

(proximal end of the femur joins with the pelvic bone)

distal

away from or farthest

(hand is located at the distal end of the arm)

mammography views

• cranio-caudal (CC) view - direction of x-rays

• medio-lateral (ML) view

• medio-lateral oblique (MLO) view

supine vs prone

• supine = face up (most common)

• prone = face down (breast imaging)

• neurological = patient left on image right = view from feet when supine (nose up)

• radiological = patient left is on image left = view from top of head when supine

coronal (frontal)

if standing, vertical plane running from side to side

divides the body or any of its parts into anterior and posterior portions

sagittal (lateral)

if standing, vertical plane running from front to back

divides the body or any of its parts into right and left sides

transverse (transaxial/axial)

if standing, horizontal plane divides the body or any of its parts into upper and lower parts

physiology

study of the functions of living organisms

general-blood pressure, heart rate, body temp

brain-cerebral blood flow, tissue oxygenation

gantry

main part of scanner, as opposed to the bed and any ancillary devices

phantom

device with known geometry/characteristics used to test or calibrate an imaging system

source

usually a source of radioactivity (often a small “point”)

subject/object

thing being imaged

image reconstruction

creating images from raw data

artifact

a feature in an image that does not represent the anatomy or physiology being measured (ring or streak)

pixel

the smallest 2D area represented in an image, usually has a single intensity value

voxel

the smallest 3D volume represented in an image, usually has a single intensity value

image matrix

the 2D or 3D array of pixels/voxels/numbers that make up a single 2D or 3D image

projection

2D representation of 3D volume

-some modalities are inherently 2D

-3D modalities can be viewed as projections too using sum or maximum intensity projection = MIP

slice/plane

2D representation of 3D volume at a certain depth only

ROI/VOI

region of interest in an image, often drawn by hand, used to determine parameters for the region such as mean or average

segmentation

process of delineating regions in an image that correspond to anatomy (often using automated computer algorithm)

FOV

field of view = physical space represented by the whole image

image fusion

viewing of 2 images of the same part of the body overlaid on each other (often complementary structural and functional images)

noise vs background

-noise is randomness in pixel/voxel (repeat same measurement and get a different value)

-background is more like a bias or offset in the pixel/voxel value, does not represent the thing you’re trying to measure (repeat the same measurement and will get the same bias)