The Evaluation and Prediction of Laminoplasty Surgery Outcome in Patients with Degenerative Cervical Myelopathy Using Diffusion Tensor MRI

X. Han; X. Ma; D. Li; J. Wang; W. Jiang; X. Cheng; G. Li; H. Guo; W. Tian

doi:10.3174/ajnr.A6705

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FIG 1.
Example of DTI planes and ROI drawings from 1 patient. A, T2-weighted structural image with the locations of the C2 level and AC levels. B, ROI drawing at C2. C–E, ROI drawings at the AC levels. D, The MC level. Four DTI metrics were measured, including FA, AD, RD, and MD.
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FIG 2.
ROC analysis of the predictive value of DTI metrics for the postoperative mJOA recovery rate. Results for the average of all AC levels, MC level, and the C2 level, respectively. The area under the curve values for different metrics are shown in Table 11.

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Table 1:

Summary of previous studies about prediction of DCM surgery outcome using DTI

Publications	Correlation Method	Significance	DTI Metrics	Prediction Indexes	Vertebral Levels	Surgery Method
Jones et al, 2013⁹	Spearman	No	FA	mJOA	MC level, C2–C3	Not specified
Wen et al, 2014¹⁵	Spearman	Yes	FA	mJOA recovery rate	Average of C3 to C7	Not specified
Vedantam et al, 2017⁵	Pearson	Yes	FA	ΔmJOA	MC level	Not specified
Maki et al, 2017¹⁶	Spearman	Yes	FA	ΔmJOA, mJOA recovery rate	MC level	Posterior and anterior
Kitamura et al, 2020¹⁷	Spearman	Yes	FA	ΔmJOA, mJOA recovery rate	MC level	Posterior
Shabani et al, 2019¹⁸	Intraclass correlation coefficient	Yes (–)	FA	ΔmJOA	MC level	Not specified
Iwasaki et al, 2019¹⁴	Pearson	No	FA	mJOA	MC level	Posterior and anterior

Note:—(–) indicates negative correlation; ΔmJOA, difference between pre- and postoperative mJOA.

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Table 2:

Comparison of DTI metrics between patients before surgery and the control group for the MC level

Groups/Statistics	MD (10⁻³mm²/s)		AD (10⁻³mm²/s)		RD (10⁻³mm²/s)		FA
Groups/Statistics	Patients	Controls	Patients	Controls	Patients	Controls	Patients	Controls
Group 1^{^a}	0.97 ± 0.16	0.72 ± 0.04	1.40 ± 0.11	1.35 ± 0.06	0.75 ± 0.21	0.40 ± 0.04	0.41 ± 0.14	0.66 ± 0.04
t/t' value	t' = −4.32		t' = −1.24		t' = −4.65		t' = 4.84
P value	P = .003^{^d}		P = .25		P = .002^{^d}		P = .002^{^d}
Group 2^{^b}	0.97 ± 0.17	0.73 ± 0.04	1.51 ± 0.16	1.32 ± 0.08	0.70 ± 0.21	0.44 ± 0.04	0.48 ± 0.14	0.61 ± 0.04
t/t' value	t' = −6.40		t' = −4.78		t' = −5.59		t' = 4.311
P value	P < .001^{^d}		P < .001^{^d}		P < .001^{^d}		P < .001^{^d}
Group 3^{^c}	0.99 ± 0.20	0.75 ± 0.05	1.47 ± 0.15	1.26 ± 0.10	0.76 ± 0.26	0.49 ± 0.04	0.43 ± 0.16	0.55 ± 0.05
t/t' value	t' = −5.89		t = −5.42		t' = −5.01		t' = 3.51
P value	P < .001^{^d}		P < .001^{^d}		P < .001^{^d}		P = .001^{^d}

↵a Group 1 of patients: MC level at C3–4 (n = 8).
↵b Group 2 of patients: MC level at C4–5 (n = 22).
↵c Group 3 of patients: MC level at C5–6 or C6–7 (n = 25).
↵d Significant correlation.

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Table 3:

Comparison of DTI metrics between patients before surgery and the control group for the average of AC levels

Groups/Statistics	MD (10⁻³mm²/s)	AD (10⁻³mm²/s)	RD (10⁻³mm²/s)	FA
Patients (n = 55)	0.87 ± 0.12	1.40 ± 0.12	0.61 ± 0.14	0.50 ± 0.10
Controls (n = 20)	0.73 ± 0.03	1.31 ± 0.07	0.44 ± 0.03	0.61 ± 0.03
t/t' value	t' = −8.19	t = −3.15	t' = −8.36	t' = 7.10
P value	P < .001^{^a}	P < .001^{^a}	P < .001^{^a}	P < .001^{^a}

↵a Significant correlation.

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Table 4:

Comparison of DTI metrics between the patients before surgery and the control group for the C2 level

Groups/Statistics	MD (10⁻³mm²/s)	AD (10⁻³mm²/s)	RD (10⁻³mm²/s)	FA
Patients (n = 52)	0.74 (0.71–0.77)^{^a}	1.35 (1.33–1.42)	0.42 (0.39–0.47)	0.64 (0.59–0.67)
Controls (n = 20)	0.75 (0.72–0.79)	1.43 (1.33–1.48)	0.41 (0.37–0.45)	0.68 (0.64–0.70)
Z value	Z = −0.33	Z = −1.62	Z = −1.04	Z = −2.44
P value	P = .74	P = .10	P = .30	P = .02^{^b}

↵a Mean (lower bound-upper bound).
↵b Significant correlation.

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Table 5:

Spearman correlations between the DTI metrics at different levels and mJOA before surgery

Levels/DTI Metrics	Correlation Coefficient	P Value
MC level (n = 55)
MD	–0.13	.34
AD	–0.13	.34
RD	–0.07	.62
FA	–0.004	.98
Average of AC levels (n = 55)
MD	–0.15	.27
AD	–0.12	.39
RD	–0.12	.38
FA	0.07	.61
C2 level (n = 52)
MD	–0.09	.55
AD	0.36	.008^{^a}
RD	–0.29	.04^{^a}
FA	0.35	.01^{^a}

↵a Significant correlation.

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Table 6:

Spearman correlations between the DTI metrics at the MC level and mJOA at 2 follow-up stages after surgery

Follow-Up Stages/DTI Metrics	Correlation Coefficient	P Value
3-Month follow-up (n = 44)
MD	–0.12	.41
AD	–0.09	.54
RD	–0.10	.51
FA	0.10	.51
6-Month follow-up (n = 37)
MD	–0.31	.04^{^a}
AD	–0.14	.36
RD	–0.32	.03^{^a}
FA	0.33	.03^{^a}

↵a Significant correlation.

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Table 7:

Spearman correlations between the DTI metrics for C2 level and mJOA at 2 follow-up stages after surgery

Follow-Up Stages/DTI Metrics	Correlation Coefficient	P Value
3-Month follow-up (n = 44)
MD	–0.20	.21
AD	0.16	.33
RD	–0.35	.03^{^a}
FA	0.42	.005^{^a}
6-Month follow-up (n = 37)
MD	–0.44	.01^{^a}
AD	0.15	.39
RD	–0.65	<.001^{^a}
FA	0.77	<.001^{^a}

↵a Significant correlation.

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Table 8:

Spearman correlations between the preoperative DTI metrics of different levels and the postoperative mJOA recovery rate at the final follow-up (1 year)

Levels/DTI Metrics	Correlation Coefficient	P Value
MC level (n = 55)
MD	–0.10	.34
AD	0.16	.34
RD	–0.12	.62
FA	0.19	.98
Average of AC levels (n = 55)
MD	–0.19	.16
AD	0.08	.59
RD	-0.24	.08
FA	0.26	.06
C2 level (n = 52)
MD	–0.15	.31
AD	0.40	.003^{^a}
RD	–0.42	.002^{^a}
FA	0.51	<.001^{^a}

↵a Significant correlation.

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Table 9:

Results of linear regression to examine the correlation between DTI, T1-weighted, and T2-weighted features and preoperative mJOA

Level/Incorporated DTI Metrics	Significant Features	Slope (β)	P Value
MC level (n = 55)
MD/AD/RD/FA	Axial spinal cord area	0.05	.01
Average of AC levels (n = 55)
MD/AD/RD/FA	Axial spinal cord area	0.05	.01
C2 level (n = 52)
MD	MD	–10.28	.03
MD	Spinal cord flattened rate	9.00	.005
AD	AD	5.58	.04
AD	Spinal cord flattened rate	6.38	.04
RD	RD	–8.93	.002
RD	Spinal cord flattened rate	8.32	.006
FA	FA	9.43	.002
FA	Spinal cord flattened rate	7.12	.02

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Table 10:

Results of linear regression to examine the correlation between DTI, T1-weighted, and T2-weighted features and the mJOA recovery rate

Level Incorporated DTI Metrics	Significant Features	Slope (β)	P Value
MC level (n = 55)
MD/AD/RD/FA	Axial spinal cord area	0.70	.02
Average of AC levels (n = 55)
MD/AD/RD	Axial spinal cord area	0.70	.02
FA	FA	108.67	.01
FA	Spinal cord flattened rate	105.64	.03
C2 level (n = 52)
MD	MD	–157.98	.04
MD	Spinal cord flattened rate	141.57	.01
AD	AD	123.60	.01
RD	RD	–145.13	.004
RD	Spinal cord flattened rate	131.88	.01
FA	FA	170.92	.001
	Spinal cord flattened rate	111.82	.02

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Table 11:

Prediction capability of the preoperative DTI metrics at different levels for the postoperative mJOA recovery rate using ROC analysis

Level/DTI Metrics	AUC	P Value	Sensitivity	Specificity
MC level (n = 55)
MD	0.46	.66	0.63	0.47
AD	0.64	.10	0.37	0.94
RD	0.43	.40	0.21	0.88
FA	0.62	.15	0.63	0.65
Average of AC levels (n = 55)
MD	0.40	.26	0.16	0.88
AD	0.57	.43	0.63	0.59
RD	0.36	.09	0.95	0.06
FA	0.65	.07	0.34	0.94
C2 level (n = 52)
MD	0.43	.39	0.97	0.06
AD	0.64	.12	0.39	0.88
RD	0.34	.07	0.97	0.06
FA	0.68	.04^{^a}	0.56^{^a}	0.81