Digital Signal Processing Reference
In-Depth Information
BENIGN versus MALIGNANT : TOTAL SHAPE SPECTRA ; FFT (Left) , FPT (Right) ; FID LENGTH : N/16 = 64, N = 1024
Fourier Absorption Total Shape Spectrum
Pade Absorption Total Shape Spectrum
5000
50
3000
B
0
14.1T
≈
Benign
B
0
≈
14.1T
Lac
Benign
2000
N/16 = 64 (N = 1024)
FPT
(−)
Glc
1000
40
N/16 = 64 (N = 1024)
500
FFT
300
Converged
Ala
Gln
30
200
100
Val
Lys
Thr
Crn
50
20
Cr
30
20
10
10
Cho
Iso
Met
5
3
0
2
1
−10
0.5
5
4
3
2
1.5
1
5
4
3
2
1.5
1
(i) Chemical shift (ppm)
(iii) Chemical shift (ppm)
Fourier Absorption Total Shape Spectrum
Pade Absorption Total Shape Spectrum
5000
120
3000
B
0
≈
14.1T
Lac
B
0
≈
14.1T
N/16 = 64 (N = 1024)
Malignant
Malignant
2000
N/16 = 64 (N = 1024)
FPT
(−)
100
1000
Gln
FFT
500
Ala
Lys
Val
80
300
Converged
Glc
Thr
200
100
60
Crn
Iso
Met
50
Cr
30
40
Cho
20
10
20
5
3
2
0
1
−20
0.5
5
4
3
2
1.5
1
5
4
3
2
1.5
1
(ii) Chemical shift (ppm)
(iv) Chemical shift (ppm)
FIGURE 9.7
Absorption spectra for cases derived from benign and malignant ovarian cyst
MRS in vitro encoded data from Ref. [343]. Top panels compare the per
formance of the FFT (left (i)) and FPT (right(iii)) at N/16 = 64 where
N = 1024 for the benign case. The FPT is fully converged, while the cor
responding FFTgenerated spectra are uninterpretable. A similar pattern is
seen in the malignant case (bottom panels, FFT (left (ii), FPT (right (iv)).
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