Topic 7 Processing Methods of Nuclear Medicine Images

• Planner Image Processing

• Region of Interest

• Clinical Image Processing Techniques

• General Tomographic Image Processing

• Specific Tomographic Image Processing

Planar Nuclear Medicine Image Processing

• Digital Images– Pixel, Matrix Size, colour or shade of Grey

• Planar Acquisition– Static, Dynamic, Gated, Dual-Isotope

• General Planar Post-processing– Interpolation, Scaling, Smoothing, Filtering,

Profile, Shift and Re-alignment.

Smoothing Operation

General Procedure - Convolution

Simple Average Filter

Nine-point Smoothing

Edge Enhancement Filter(Accentuate Contrast)

Smoothing Results

Fourier Methods of Image Enhancement

Activity Profile

Count Profile Planar Left Ventricle

Contrast and Spatial ResolutionFrom a Point Source

Simple Background Subtraction

Interpolated Background Subtraction

Frame Processing Operations

• Combination of two or more images to form one output image (Renogram).

• Subtraction of Image Pair.

• Geometric Operation (Shift, Re-align, Magnification, Minification, etc)

Region of Interest

• Creating an Region of Interest (ROI)– Circular,freehand draw, threshold, isocontour,

Laplacian edge detection

• Operation on ROI

• Region of Interest Statistics

• Background Subtraction

• Time Activity Curve

The Second Derivative Method

Zero Crossing: Activity Profile

Region of Interest

Time Activity Curve

Three Point Smoothing

Five Point Smoothing

Weighted 3-Point Smoothing

Decay Curve

Decay Curve on a Semi-log

Intensity vs Distance

Intensity vs Distance (Log Plot)

Least Square Fitting

Two Delta Function Fitting

Clinical Image Processing Techniques

• Multiple Gated Blood Pool Studies– Ejection Fraction=[( LV at ED-BG)-(LVatSD-BG)]/(LVatED-BG).

– Segmental Motion at an Angle=(ED radius at that angle - ES radius at that angle)/ED radius at that angle

• Cardiac First Pass Studies– Shunt analysis: [Pulmonary flow/Systemic flow]=[(area under first

fitted curve)/(area under first fitted curve-area under second fitted curve)]

• Cardiac Perfusion Studies – ROI, Circumferential Analysis

Ejection Fraction Calculation

Segmental Wall Motion Calculation

Circumferential Analysis

Clinical Image Processing Techniques

• Renal Studies– Total ERPF = 5.029 x 0.36987 x OIH uptake-

(0.000231476 x OIH uptake x OIH uptake) where: OIH=[(BG subtracted kidney counts x Y x Y x 100)/(1 min counts of injected radionuclide)] and Y=13.3X+0.7 and X is the patient’s weight in kilograms divided by height in cm.

– GFR=(%renal uptake of DTPA) x 9.81270-6.82519 where (%renal uptake of DTPA) =[(Right kidney BG corrected counts + Left kidney BG corrected counts)]/[exp(-0.153Y)/(pre-injected counts)].

Renogram

Clinical Image Processing Techniques

• Gastric Emptying– Solid phase, liquid phase or combined.– Anterior and posterior static images– Time activity curve is constructed and half time

is calculated.

• Parathyroid Imaging– Dual isotope acquisition (scatter correction)– Region of Interest Analysis.

Tomographic Image Processing Techniques

• Acquisition

• Filtered Backprojection

• Attenuation Correction

Tomography

Filters

General Tomographic Image Processing

• Oblique Re-orientation (Reslice etc)

• Display(a set of slices)

• Region of Interest(simultaneously multiple slice processing)

• Operation on Tomographic ROIs (ROI statistics, Background Subtraction, Time Activity Curve)

Brain Perfusion Tomogram

Oblique Cardiac Sections

Specific Tomographic Image Processing Techniques

• Cardiac Perfusion Tomographic Processing– 3D extension of planar processing techniques– Bull’s eye or polar display– Stress and rest perfusion compared to normals

• Tomographic Cerebral Blood Flow and Metabolism Processing– ROI: Left and Right symmetry– Ratio of Different Regions.

Cardiac Perfusion Analysis

Stress and Rest Cardiac Perfusion -Normal

Stress and Rest Cardiac Perfusion -Abnormal

Perfusion Rates of Brain Region of Interest