ADC Change with Pixel ShiftADC Change with Pixel Shift

Joshua Kim

I. Review

II. Analysis Procedure

III. ADC and Error Calculations

IV. Current ADC Variation Results

V. Future Work

Outline

Review

• Problem:– Some lesions are very difficult to

contour

– Would like to study lesion pixel variation with translation.

– Also: Want good organization of data and fast analysis

• MatLab:– User defined contours for b=0, 520 and 850.

– Record coordinates (indices) of contour

– Shift in 8 different directions by N pixels

– Create ADC value plots as function of shift to study the pixel variations

– Conclude effect of transcription uncertainty

Review

b = 0 b = 520 b = 850

Analysis Procedure

• Characterize data sets

• Update spreadsheet log

• Perform Analysis, save workspace for future analysis if needed

• Make contour transcriptions independently (for each b-value scan)

• Apply shifts in different directions, obtain ADC values as a function of shift

ADC and Error Calculations• Calculations from paper:

• Matlab code:

Directions for ADC Calculations

Patient Mejia, Slice 2b = 0

50 100 150 200 250

50

100

150

200

250

b = 520

50 100 150 200 250

50

100

150

200

250

b = 850

50 100 150 200 250

50

100

150

200

250

ADC Variation with Pixel Shift

-50 -40 -30 -20 -10 0 10 20 30 40 50-2

-1

0

1

2

3

4

5

6

7

8x 10

-3 ADC Values with Shift

pixel shift

AD

C V

alue

s

Vertical

Horizontal-45 deg

+45 deg

Patient Mejia, Slice 3b = 0

50 100 150 200 250

50

100

150

200

250

b = 520

50 100 150 200 250

50

100

150

200

250

b = 850

50 100 150 200 250

50

100

150

200

250

ADC Variation with Pixel Shift

-50 -40 -30 -20 -10 0 10 20 30 40 50-6

-4

-2

0

2

4

6x 10

-3 ADC Values with Shift

pixel shift

AD

C V

alue

s

Vertical

Horizontal-45 deg

+45 deg

Future Work

• Continue with contour transcriptions

• Analyze remaining data sets (and maintain log files)

• Study effects relative to erosion/dilation

• Goal: Create 3D ADC variation maps for a user defined contour (assumes b=0 to b=850 data sets are spatially equal)

Future Work