Article Figures & Data
Figures
- FIGURE 1.
(A) Noisy simulated curve (solid) and associated Legendre transform (dashed). (B) Values of 23 first Legendre coefficients obtained using Equation 3 and corresponding kmax.
- FIGURE 2.
(A) Raw MC data curves (solid) with corresponding denoised signal by FLT (dashed and dotted). Top curve is left kidney; bottom curve is right kidney. (B) Spectrum of first Legendre coefficients for left kidney in A. (C) Spectrum of first Legendre coefficients for right kidney in A. B and C have same kmax (coefficient number, 16).
- FIGURE 3.
(A) Raw patient data curves (solid) with corresponding denoised signal by FLT (dashed and dotted). Top curve is left kidney; bottom curve is right kidney. (B) Spectrum of first Legendre coefficients for left kidney in A. (C) Spectrum of first Legendre coefficients for right kidney in A. In this case, kmax slightly differed between the 2 kidneys: 11 for left and 12 for right.
- FIGURE 4.
Box plot of Tmax obtained by 3 methods for left and right kidneys in MC simulations, showing clearance of 260 (A) and 130 (B) mL/min. Horizontal black lines represent expected (true) values given in Table 1.
- FIGURE 5.
Fitted time–activity curve obtained with FLT (dashed) or F121 and optimum number of passes (dotted) of raw time–activity curve (solid) and computed kinetic parameters for each method.
- FIGURE 6.
Bland–Altman plot of agreement between Tmax obtained by FLT and F121 for left (A) and right (B) kidneys in patients.
Tables
Study LRF (%) Tmax for both kidneys (min) T1/2 LK (min) T1/2 RK (min) Clearance (mL/min) 1 50 2 20 3.7 6.6 6.2 260 3 70 4 50 5 20 4.0 9.8 9.2 130 6 70 Each study contains 5 series with 1 posterior RS and 2 posterior and anterior studies with 100 and 50 MBq, respectively, of injected activity. Time values were obtained from RS.
- TABLE 2
Results for 12 Simulations of RMS Error Between RS and RS with Poisson Noise Added for Different Processing Methods
Processing method Mean SD None 57.8* 14.3 FLT 18.1 3.6 F121, 2 passes 32.8* 5.7 F121, 4 passes 34.6* 4.0 F121, 6 passes 39.0* 4.2 F121, 8 passes 43.6* 4.7 ↵* Statistically different from FLT (P < 0.0001).
Data are for 6 methods and 2 kidneys. Number of coefficients for FLT was automatically determined, and number of F121 passes was varied from 2 to 8.
Parameter Slope R2 Intercept (%) Hermes − FLT 0.975 0.996 1.317 Hermes − F121 0.966 0.996 1.753 FLT − F121 0.990 0.999 0.495 Mean (min) SD (min) MSE Hermes/FLT Hermes/F121 F121/FLT Study E (min) Hermes FLT F121 Hermes FLT F121 Hermes FLT F121 F P F P F P Tmax 1–3 3.7 3.77 3.74 3.78 0.59 0.19 0.28 0.34 0.04 0.08 10.13 <0.001* 4.55 <0.001* 2.23 0.017* Tmax 4–6 4.0 3.9 3.95 4.08 0.60 0.29 0.50 0.36 0.08 0.24 4.34 <0.001* 1.48 0.15 2.93 0.002* T1/2 LK 1–3 6.6 4.96 6.49 6.39 1.72 0.30 0.42 5.47 0.10 0.21 32.62 <0.001* 16.87 <0.001* 1.93 0.11 T1/2 RK 1–3 6.2 5.44 6.21 6.29 0.82 0.21 0.25 1.20 0.04 0.07 15.15 <0.001* 10.66 <0.001* 1.42 0.25 T1/2 LK 4–6 9.8 6.34 9.37 9.27 2.97 0.81 1.28 20.22 0.80 1.82 13.35 <0.001* 5.35 0.002* 2.49 0.05 T1/2 RK 4–6 9.2 7.03 9.3 9.18 1.75 0.62 0.89 7.54 0.37 0.75 7.83 <0.001* 3.83 0.008* 2.04 0.10 ↵* Statistically significant under Holm–Bonferroni adjustment for multiple comparisons.
E = expected value from Table 1; MSE = mean squared error (
/N).Mean, SD, and MSE are from expected value for studies 1–3 with clearance of 260 mL/min and studies 4–6 with clearance of 130 mL/min. Hermes/FLT, Hermes/F121, and F121/FLT are ratio of variance obtained with F test and associated P value. LK = left kidney; RK = right kidney.
- TABLE 5
Bias and SD Obtained from Bland–Altman Analysis of Different Parameters for Each Pairwise Method Comparison on Patient Data
Bias SD Parameter Hermes − FLT Hermes − F121 FLT − F121 Hermes − FLT Hermes − F121 FLT − F121 LRF (%) 0.025 0.15 0.125 1.48 1.54 0.72 Tmax LK −0.62 −0.46 −0.15 1.89 1.85 0.39 Tmax RK 0.24 0.22 −0.02 1.9 1.79 0.35 T1/2 LK −4.09 −3.9 0.23 4.73 4.72 0.54 T1/2 RK −2.82 −2.06 0.1 3.77 3.11 0.65 LK = left kidney; RK = right kidney.
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