Bioimaging Midterm 1

Image

2D rep of physical quantity.

Image Attributes (3)

Xray Attenuation

Proton Density

Acoustic Reflectivity

Anatomical imaging

How organ “Looks”

Functional imaging

How organ “Works”

Projection

Single planar representation

Tomographic

Show cross-section (cut)

Transmission (3)

Passes through object

Loses Depth Information

Superimposes (Layers)

Reflection (2)

Rays bounces off object

Depth information by time

Image Planes (3)

Axial / Transverse (Top to Bottom)

Sagittal (Side to Side)

Frontal / Coronal (Front to Back)

Anatomical Modalities (4)

CT

MRI

Projection Xray

Ultrasound

Functional Modalities (4)

CT

MRI

Ultrasound

PET / SPECT

Ionizing Modalities

Projection Xray

CT

PET / SPECT

Not Ionizing, why? (2)

MRI - uses magnets

Ultrasound

Tomographic Modalities (4)

CT

MRI

PET / SPECT

Ultrasound

Resolution (1 + 3)

Pixels per Inch (FOV / Image Matrix Size)

Pixel: 2D array of Picture Elements

IMS: # of pixels in image

Greyscale

8 bit and 16 bit (2^n - 1)

Denoise

Higher and clearer quality.

Can remove details due to smoothing of image.

E Threshold

Eth > 1 keV

Equations

c = L * f

E = h * f

Binding energy of Hydrogen

13.6 ev

Projection Xray Modalities

Transmission & Projection Geometry

Projection Xray Pros and Cons

Pros:

Cheap, Simple to use, Low Dosage, Portable, Fast

Cons:

Ionizing, Poor Depth Resolution

CT Modalities

Transmission & Tomographic

CT Pros and Cons

Pros:

Excellent Resolution, Adjustable Quantitative info

Cons:

Complex, expensive, not portable, higher dosage, slower

Ultrasound Modalities

Reflection, echoes received based on time and distance

Ultrasound Pros and Cons

Pros:

Cheap, Fast (Real-time), Portable, Great DEPTH Resolution, non-ionizing, simple

Cons: Poor ANGULAR Resolution, Mat. specific limits, depth limited

MRI Modalities

Precession (Magnets), Tomographic

MRI Pros and Cons

Pros:

Great soft tissue contrast, great resolution, non-ionizing

Cons:

Expensive, complex, slow, not portable

Pet/Spect Modalities

Emission, tomographic (scintigraphy = gamma detection)

Pet/Spect Pros and Cons

Pros:

Functional resolution, tomographic

Cons:

Poor spatial resolution, complex, not portable, ionizing, expensive, high dosage, slow

Dosage

PET/SPECT > CT > Projection Xray >/> MRI & Ultrasound

Speed

Fast: Projection Xray > Ultrasound

Slow: CT, MRI, PET/SPECT