Use of Laser Speckle Contrast Imaging to Assess Digital Microvascular Function in Primary Raynaud Phenomenon and Systemic Sclerosis: A Comparison Using the Raynaud Condition Score Diary

John D. Pauling; Jacqueline A. Shipley; Darren J. Hart; Anita McGrogan; Neil J. McHugh

doi:10.3899/jrheum.141437

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Figure 1.
Objective assessment of digital vascular function in a patient with SSc complicated by recurrent digital ulceration. A. A photograph demonstrating the visual appearances of the hands on arrival for assessment with evidence of digital cyanosis and shortening of index fingers because of previous necrotic episodes. B. An IRT image of baseline assessment of digital vascular function with the 3 ROI highlighted. C. LSCI images at 13-s intervals during baseline and following cold challenge (the hands disappearing from view during cold challenge). SSc: systemic sclerosis; IRT: infrared thermography; ROI: region of interest; LSCI: laser speckle contrast imaging.

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Table 1.

Baseline demographics of patients. Values are median (IQR) unless otherwise specified.

Characteristics	Primary RP, n = 18	SSc, n = 25	p
Age, yrs	51.7 (19.3)	59.2 (19.8)	0.03
Age at RP onset, yrs	20 (24)	35 (19)	0.02
Age at diagnosis, yrs	43 (6)	45 (19)	0.61
Male, n (%)	4 (22.2)	5 (20)	1.00
Female, n (%)	14 (77.8)	20 (80)	1.00
Vasodilatory therapy
Any, n (%)	5 (27.8)	12 (48)	0.22
Calcium antagonist	3 (16.7)	6 (24)	0.71
ACEi	0 (0)	7 (28)	0.03
SSRI	2 (11.1)	1 (4)	0.56
ERA	0 (0)	2 (8)	0.50
Smoking history, n (%)
Never	10 (55.6)	13 (52)	1.00
Ex	7 (38.9)	9 (36)	1.00
Current	1 (5.5)	3 (12)	0.63
Season enrolled, n (%)
Autumn/winter	10 (55.6)	13 (52)	1.00
Spring/summer	8 (44.4)	12 (48)	1.00

Significant data are in bold face. IQR: interquartile range; RP: Raynaud phenomenon; SSc: systemic sclerosis; ACEi: angiotensin-converting enzyme inhibitor; SSRI: selective serotonin reuptake inhibitors; ERA: enthesitis-related arthritis.

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Table 2.

IRT and LSCI data for patients with SSc and primary RP at assessment 1. All values expressed as median (IQR).

Variables	ROI	B	t0	t5	t10	t15
IRT, °C
SSc
	1	29.8 (5.5)^*	21.5 (2.6)^†	23.7 (7.1)^*	25.4 (9.2)^*	27 (9.4)^*
	2	30.8 (7.3)	21.4 (2.9)	24.4 (7.9)	25 (9.7)	26.7 (11.1)
	3	28.8 (6.4)	20.6 (3.0)^*	22.4 (6.2)^*	24 (8.8)^*	25.9 (9.4)
Primary RP	1	31.4 (8.0)^†	21.1 (3.2)^†	25.1 (9.5) ^{^*^†}	31.4 (11)	32.4 (10.8)
	2	30.8 (6.6)	21.5 (3.5)	25.2 (7.2)	30.4 (10.5)	31.7 (10.6)
	3	29.5 (6.7)	20.7 (3.1)^*	23.5 (9.6)	30.5 (10.5)	32 (10)
LSCI, fu
SSc	1	364 (299)^†	188 (177)^*	205 (282)^*	243 (257)^†	298 (288)^†
	2	235 (306)^**	79 (84)	100 (269)	132 (391)	128 (364)
	3	632 (757)^*	213 (424)^*	320 (642)^*	422 (955)^*	479 (770)^*
Primary RP	1	372 (378)^*	179 (128)^*	274 (346)^*	452 (430)^*	488 (446)^*
	2	124 (93)	81 (61)	81 (81)	104 (161)	120 (128)
	3	536 (483)^*	202 (135)^*	261 (577)^*	484 (604)^*	487 (672)^*

↵* p < 0.05 vs ROI 2.
↵† p < 0.05 vs ROI 3.
↵** p = 0.007 vs primary RP. IRT: infrared thermography; LSCI: laser speckle contrast imaging; SSc: systemic sclerosis; RP: Raynaud phenomenon; IQR: interquartile range; ROI: region of interest; B: baseline assessment at 23°C; t0: assessments immediately following cold challenge; t5: perfusion 5 min post cold challenge; t10: perfusion 10 min post cold challenge; t15: perfusion 15 min post cold challenge; fu: flux unit values.

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Table 3.

Correlation between objective and subjective assessment of RP at baseline and following cold challenge for both primary RP and SSc. Values are r_s.

Correlation between IRT and LSCI. p < 0.01 for all comparisons.

	B	t0	t5	t10	t15

ROI 1	0.73	0.62	0.81	0.84	0.75
ROI 2	0.70	0.58	0.84	0.83	0.81
ROI 3	0.81	0.65	0.82	0.82	0.83

Correlation between the RCS diary and LSCI assessment at ROI. 1 p > 0.05 for all comparisons.

Duration of RP attacks	0.05	−0.20	0.01	0.08	0.07
Frequency of RP attacks	0.02	−0.19	−0.08	0.02	0.02
RCS	−0.02	−0.01	0.01	0.00	0.00

RP: Raynaud phenomenon; SSc: systemic sclerosis; IRT: infrared thermography; LSCI: laser speckle contrast imaging; ROI: region of interest; B: baseline assessment at 23°C; t0: assessments immediately following cold challenge; t5: perfusion 5 min post cold challenge; t10: perfusion 10 min post cold challenge; t15: perfusion 15 min post cold challenge; RCS: Raynaud Condition Score.

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Table 4.

Reproducibility of IRT and LSCI for each ROI at baseline and following cold challenge for both primary RP and SSc. Values are ICC (95% CI). N = 41, unless stated otherwise.

ROI	Camera	B	t0	t5	t10	t15
1	IRT^*	0.51 (0.24–0.71)	0.61 (0.36–0.78)	0.52 (0.25–0.72)	0.5 (0.23–0.7)	0.54 (0.28–0.73)
1	LSCI	0.62 (0.39–0.78)	0.86 (0.75–0.92)	0.52 (0.25–0.71)	0.34 (0.04–0.58)	0.47 (0.19–0.68)
2	IRT^*	0.51 (0.24–0.71)	0.56 (0.3–0.75)	0.54 (0.28–0.73)	0.54 (0.28–0.73)	0.55 (0.28–0.73)
2	LSCI	0.63 (0.4–0.78)	0.59 (0.33–0.76)	0.65 (0.43–0.79)	0.54 (0.28–0.73)	0.30 (0–0.55)
3	IRT^**	0.59 (0.33–0.76)	0.6 (0.35–0.77)	0.55 (0.28–0.73)	0.63 (0.4–0.79)	0.70 (0.5–0.83)
3	LSCI^*	0.55 (0.29–0.73)	0.79 (0.63–0.89)	0.5 (0.22–0.7)	0.42 (0.13–0.65)	0.55 (0.29–0.73)

↵* n = 40.
↵** n = 39. IRT: infrared thermography; LSCI: laser speckle contrast imaging; ROI: region of interest; RP: Raynaud phenomenon; SSc: systemic sclerosis; B: baseline assessment at 23°C; t0: assessments immediately following cold challenge; t5: perfusion 5 min post cold challenge; t10: perfusion 10 min post cold challenge; t15: perfusion 15 min post cold challenge.