Optimal pressure for measuring objective lymphedema with postoperative ultrasonography in patients with breast cancer

Figures & data

Figure 1. Measurement sites were centers of upper-arm and forearm. Three points were marked before measurement (A) the midpoint of the medial and lateral epicondyles, (B) the midpoint of the bicipital groove, (C) the midpoint of the radial and ulnar styloid processes). Two points were measured with ultrasonography 10 cm proximal and distal from A. These points were on the lines between A and B and between A and C.

Figure 2. Ultrasonography (USG) with a linear transducer equipped with a pressure sensor was used to evaluate lymphedema tissue. Using a constant velocity controller, the arm was compressed down at a constant velocity using a precision instrument (0.8 mm/sec). The pressure signal was recorded in the computer using a data acquisition system.

Figure 3. (A) Ultrasonographic B-mode and M-mode images were matched with real-time pressure measurements using Matlab. After confirmation of skin, subcutaneous tissue and muscle layer in B mode, M mode was started with pressure monitoring system. From the top of M mode, arrowhead is skin, arrow is subcutaneous tissue and the lighter gray space (curved arrow) is the muscle layer. Pressure increased constantly until the thickness of subcutaneous layer no longer changed. (B and C) It plotted the real-time change in thickness and force over time. Red and green lines are the thickness of subcutaneous tissue and skin with time. The blue line is the change of compressive force with time.

Table 1. Demographic characteristics of patients with lymphedema who underwent ultrasonographic measurements.

Affected arms	Right arm	Left arm	p Value	Total
Age (years old)	59.3 ± 8.6	58.9 ± 9.5	.931	59.1 ± 8.8
Height (cm)^a	156.5 ± 3.5	159.9 ± 4.1	.135	158.3 ± 4.1
Weight (Kg)^a	57.1 ± 6.2	60.4 ± 8.4	.435	58.9 ± 7.3
BMI (Kg/m^2)^a	23.2 ± 1.5	23.7 ± 3.4	.709	23.5 ± 2.6
Duration of lymphedema (months)	40.4 ± 31.4	26.6 ± 22.2	.353	33.1 ± 26.8
Involved lymph node (number)^a	7.2 ± 7.0	6.2 ± 6.3	1.000	6.7 ± 6.4
Tumor stage (number[percent])^a
IIa	0 [0.0%]	1 [12.5%]	.757	1 [7.1%]
IIb	2 [33.3%]	2 [25.0%]		4 [28.6%]
IIIa	3 [50.0%]	1 [12.5%]		4 [28.6%]
IIIb	1 [16.7%]	4 [50.0%]		5 [35. %7]
Operation (number[percent])
Quadrantectomy	3 [42.9%]	4 [50.0%]	.870	7 [46.7%]
Modified radical mastectomy	4 [57.1%]	3 [37.5%]		7 [46.7%]
Total mastectomy	0 [0.0%]	1 [12.5%]		1 [6.7%]
Radiotherapy (number[percent])
No	1 [14.3%]	1 [12.5%]	1.000	2 [13.3%]
Yes	6 [85.7%]	7 [87.5%]		13 [86.7%]
Chemotherapy (number[percent])			–
No	0 [0.0%]	0 [0.0%]		0 [0.0%]
Yes	7 [100.0%]	8 [100.0%]		15 [100.0%]

^a Missing cases are two cases in height, weight, and BMI, three cases in involved lymph node, and one case in tumor stage. Categorical data were analyzed by Fisher’s exact test and linear by linear association. Continuous data were analyzed by the Mann–Whitney U-test.

Table 2. The thickness and the ratio of thickness change in upper arm and forearm by compression in healthy subjects.

	Upper arm^a		Forearm^a
Neuton	Thickness (mm)	Ratio of thickness change	Thickness (mm)	Ratio of thickness change
0.0	2.03 ± 1.09	0.00 ± 0.00	1.84 ± 0.80	0.00 ± 0.00
1.0	2.03 ± 1.09	0.00 ± 0.00	1.84 ± 0.80	0.00 ± 0.00
1.1	1.53 ± 0.76	0.22 ± 0.15	1.42 ± 0.60	0.22 ± 0.14
1.2	1.35 ± 0.65	0.31 ± 0.15	1.32 ± 0.56	0.28 ± 0.13
1.3	1.25 ± 0.57	0.36 ± 0.11	1.25 ± 0.54	0.32 ± 0.11
1.4	1.22 ± 0.55	0.37 ± 0.11	1.23 ± 0.54	0.34 ± 0.12
1.5	1.19 ± 0.55	0.38 ± 0.11	1.20 ± 0.55	0.35 ± 0.11
1.6	1.18 ± 0.55	0.38 ± 0.11	1.19 ± 0.55	0.36 ± 0.11
1.7	1.17 ± 0.55	0.39 ± 0.11	1.18 ± 0.55	0.37 ± 0.10
1.8	1.17 ± 0.55	0.39 ± 0.11	1.18 ± 0.55	0.37 ± 0.10
1.9	1.16 ± 0.55	0.39 ± 0.11	1.18 ± 0.55	0.37 ± 0.10
2.0	1.16 ± 0.54	0.39 ± 0.11	1.18 ± 0.54	0.37 ± 0.10
2.1	1.16 ± 0.54	0.39 ± 0.11	1.18 ± 0.54	0.37 ± 0.10

^a Values are mean ± standard deviation. The ratio of thickness change was calculated as (Initial thickness-thickness with compression)/(Initial thickness).

Table 3. Comparison of the thickness and the ratio of thickness change between unaffected and affected sides in upper arm and forearm by compression in lymphedema patients^a.

	Upper arm^b						Forearm^b
	Thickness (mm)			Ratio of thickness change			Thickness (mm)			Ratio of thickness change
Neuton	Unaffected arms	Affected arms	p Value	Unaffected arms	Affected arms	p Value	Unaffected arms	Affected arms	p Value	Unaffected arms	Affected arms	p Value
0.0	3.78 ± 1.27	4.35 ± 1.45	.125	0 ± 0	0 ± 0	1.000	3.36 ± 0.80	4.95 ± 1.70	.020	0 ± 0	0 ± 0	1.000
0.5	3.01 ± 1.16	3.49 ± 1.42	.140	0.21 ± 0.08	0.21 ± 0.06	1.000	2.72 ± 0.81	4.31 ± 1.78	.006	0.20 ± 0.09	0.14 ± 0.09	.012
1.0	2.59 ± 1.04	2.99 ± 1.20	.156	0.32 ± 0.07	0.32 ± 0.05	.650	2.45 ± 0.76	3.92 ± 1.78	.011	0.27 ± 0.08	0.23 ± 0.11	.041
1.5	2.47 ± 0.94	2.83 ± 1.06	.156	0.35 ± 0.07	0.35 ± 0.04	.496	2.35 ± 0.70	3.73 ± 1.74	.011	0.31 ± 0.07	0.27 ± 0.22	.061
2.0	2.40 ± 0.89	2.73 ± 1.03	.191	0.37 ± 0.06	0.38 ± 0.05	.140	2.30 ± 0.66	3.63 ± 1.67	.006	0.32 ± 0.07	0.29 ± 0.10	.069
2.5	2.36 ± 0.88	2.69 ± 1.01	.233	0.38 ± 0.05	0.39 ± 0.05	.281	2.27 ± 0.65	3.59 ± 1.64	.005	0.33 ± 0.07	0.29 ± 0.10	.078
3.0	2.32 ± 0.86	2.67 ± 1.00	.173	0.39 ± 0.05	0.39 ± 0.05	.570	2.24 ± 0.62	3.56 ± 1.62	.006	0.34 ± 0.06	0.30 ± 0.10	.047
3.5	2.29 ± 0.85	2.64 ± 0.99	.156	0.39 ± 0.05	0.40 ± 0.05	.776	2.23 ± 0.61	3.54 ± 1.60	.006	0.34 ± 0.06	0.30 ± 0.10	.047
4.0	2.27 ± 0.84	2.63 ± 0.99	.173	0.40 ± 0.05	0.40 ± 0.05	.820	2.20 ± 0.60	3.52 ± 1.60	.006	0.35 ± 0.06	0.30 ± 0.10	.041
4.5	2.25 ± 0.83	2.62 ± 0.98	.173	0.41 ± 0.05	0.40 ± 0.05	.955	2.19 ± 0.59	3.51 ± 1.59	.006	0.35 ± 0.06	0.31 ± 0.10	.036
5.0	2.25 ± 0.83	2.61 ± 0.97	.191	0.41 ± 0.05	0.40 ± 0.05	.955	2.19 ± 0.59	3.50 ± 1.58	.006	0.35 ± 0.06	0.31 ± 0.10	.041
5.5	2.24 ± 0.84	2.60 ± 0.96	.191	0.41 ± 0.05	0.40 ± 0.05	.865	2.19 ± 0.59	3.49 ± 1.58	.006	0.35 ± 0.06	0.31 ± 0.10	.053
6.0	2.23 ± 0.84	2.60 ± 0.95	.191	0.41 ± 0.05	0.41 ± 0.05	.865	2.18 ± 0.59	3.48 ± 1.58	.006	0.35 ± 0.06	0.31 ± 0.10	.053

^a Statistical analysis was done using Wilcoxon’s signed rank test. The ratio of thickness change was calculated as (initial thickness-thickness with compression)/(initial thickness).

^b Values are mean ± standard deviation.

Table 4. Reliabilities of the thickness and the ratio of thickness in upper arm and forearm by compression in healthy subjects^a.

	Upper arm				Forearm
	Thickness		Ratio of thickness change		Thickness		Ratio of thickness change
Neuton	Intrarater	Inter-rater	Intrarater	Inter-rater	Intrarater	Inter-rater	Intrarater	Inter-rater
1.0	0.999	0.999	0.999	0.999	0.998	0.995	0.999	0.999
1.1	0.996	0.996	0.981	0.905	0.995	0.993	0.978	0.965
1.2	0.998	0.996	0.988	0.970	0.998	0.990	0.976	0.954
1.3	0.999	0.998	0.987	0.984	0.997	0.996	0.949	0.946
1.4	0.999	0.998	0.989	0.985	0.998	0.997	0.978	0.970
1.5	0.999	0.998	0.992	0.983	0.998	0.997	0.968	0.962
1.6	0.999	0.998	0.993	0.981	0.998	0.997	0.972	0.962
1.7	0.999	0.998	0.989	0.984	0.998	0.997	0.967	0.959
1.8	0.999	0.998	0.990	0.985	0.998	0.997	0.974	0.963
1.9	0.999	0.998	0.986	0.979	0.998	0.997	0.975	0.961
2.0	0.999	0.998	0.988	0.983	0.998	0.997	0.975	0.964
Overall	0.997	0.996	0.987	0.985	0.996	0.995	0.973	0.968

^a Statistical analysis was done using calculation of the intraclass correlation coefficient.

Table 5. Reliabilities of the thickness and the ratio of thickness in upper arm and forearm by compression in lymphedema patients^a.

	Upper arm				Forearm
	Thickness		Ratio of thickness change		Thickness		Ratio of thickness change
Neuton	Intrarater	Inter-rater	Intrarater	Inter-rater	Intrarater	Inter-rater	Intrarater	Inter-rater
0.5	0.981	0.975	0.828	0.792^b	0.982	0.985	0.802	0.848
1.0	0.983	0.922	0.818	0.795^b	0.989	0.982	0.813	0.776^b
1.5	0.972	0.959	0.814	0.832	0.991	0.980	0.855	0.793^b
2.0	0.976	0.957	0.912	0.902	0.993	0.982	0.902	0.910
2.5	0.981	0.951	0.904	0.891	0.995	0.984	0.916	0.920
3.0	0.982	0.955	0.918	0.901	0.995	0.985	0.936	0.924
3.5	0.983	0.955	0.895	0.910	0.995	0.986	0.946	0.928
4.0	0.981	0.957	0.910	0.898	0.995	0.986	0.952	0.920
4.5	0.985	0.956	0.921	0.901	0.981	0.978	0.954	0.924
5.0	0.987	0.956	0.908	0.910	0.995	0.986	0.948	0.923
5.5	0.989	0.937	0.913	0.983	0.995	0.987	0.912	0.912
6.0	0.987	0.950	0.905	0.899	0.995	0.987	0.932	0.921
Overall	0.982	0.953	0.887	0.885	0.992	0.984	0.906	0.892

^a Statistical analysis was done using calculation of the intraclass correlation coefficient.

^b Intraclass correlation coefficient was less than 0.8.