Jacqueline Shipley

Comparison of infrared thermography and laser speckle contrast imaging for the dynamic assessment of digital microvascular function

OBJECTIVES Laser speckle contrast imaging (LSCI) is a novel non-invasive microvascular imaging modality. The present study evaluates the validity and reliability of LSCI by comparison with infrared thermography (IRT) for the dynamic assessment of digital microvascular function in healthy volunteers. METHODS Subjects attended on 3 occasions. Simultaneous assessment of cutaneous perfusion at 3 distinct regions of interest (ROI) within the hands was undertaken using LSCI and infrared thermography (IRT) at baseline, and at 13s intervals over 15 min following a standardised local cold challenge. Endpoints for evaluation included absolute measurements at baseline and following cold stress, in addition to the characteristics of the re-warming curves (maximum % recovery and maximum gradient). Visits 1 and 2 were undertaken in identical conditions (ambient temperature 23°C) to assess reproducibility, whereas visit 3 was undertaken at a lower ambient room temperature of 18°C to evaluate responsiveness to reduction in ambient room temperature. RESULTS Fourteen healthy participants completed the study. There was greater variability in the data generated using LSCI compared with the highly damped IRT, reflecting greater sensitivity of LSCI to physiological variation and movement artefact. LSCI and IRT correlated well at baseline and following cold challenge for all endpoints (r(s) for pooled data between 0.5 and 0.65, p<0.00005). Reproducibility of both IRT and LSCI was excellent (ICCs>0.75) for absolute assessments but lower for re-warming curve characteristics. LSCI provides greater spatial resolution than IRT identifying variation in cutaneous perfusion within the hands most likely associated with the presence of arteriovenous anastamoses. Both techniques were responsive to reduction in ambient room temperature. Effect sizes were greatest for IRT than LSCI (e.g. -1.17 vs. -0.85 at ROI 1 at baseline) although this may represent heat transfer rather than altered vascular perfusion. DISCUSSION In the dynamic assessment of digital vascular perfusion, LSCI correlates well with IRT, is reproducible and responsive to reduction in ambient room temperature. Absolute measurements appear preferable to parameters derived from re-warming curve characteristics when assessing digital perfusion following cold challenge. The greater temporal and spatial resolution of LSCI compared with IRT may facilitate the development of novel assessment tools of autonomic function and digital cutaneous perfusion.

A Multicenter Study of the Validity and Reliability of Responses to Hand Cold Challenge as Measured by Laser Speckle Contrast Imaging and Thermography: Outcome Measures for Systemic Sclerosis–Related Raynaud's Phenomenon

Reliable and objective outcome measures to facilitate clinical trials of novel treatments for systemic sclerosis (SSc)–related Raynauds phenomenon (RP) are badly needed. Laser speckle contrast imaging (LSCI) and thermography are noninvasive measures of perfusion that have shown excellent potential. This multicenter study was undertaken to determine the reliability and validity of a hand cold challenge protocol using LSCI, standard thermography, and low‐cost cell phone/mobile phone thermography (henceforth referred to as mobile thermography) in patients with SSc‐related RP.

Impaired digital vascular function mimicking Raynaud's phenomenon as a complication of argon laser therapy in tuberous sclerosis

A 55-year-old male was referred with a classical description of severe digital pallor and pain in response to cold exposure consistent with Raynauds phenomenon (RP). There were no additional clinical features of connective tissue disease. There was no evidence of macrovascular disease or a history of vibrating tool use. Past medical history included tuberous sclerosis (TS), hypertension and pernicious anaemia, forwhichhe received treatmentwith perindopril and regular vitamin B12 injections. Antinuclear antibody investigations (HEp-2 cell substrate) were negative. Serum protein, globulins, glucose and lipids were within normal range. Thyroid function was normal. Thermal imaging during cold stress test was consistent with Raynauds phenomenon but with changes limited to his index and middle fingers bilaterally (Fig. 1). The absence of any response to dynamic testing was suggestive of irreversible vascular dysfunction. It subsequently emerged that his symptoms had developed shortly following argon laser therapy to periungual fibromas on the affected digits. Use of laser therapy for the management of cutaneous lesions of TS is well described (Pasyk and Argenta, 1988; Janniger and Goldberg, 1990; Boixeda et al., 1994). Response to treatment with laser therapy

Raynaud’s phenomenon and macrocytic anaemia

A 50 year old man was referred to our rheumatology unit with an 18 month history of classic Raynaud’s phenomenon with episodic digital pain and biphasic (white-blue) colour changes associated with cold exposure. He had noticed that his urine was dark during periods of cold weather. He had a macrocytic anaemia but normal serum levels of vitamin B-12 and folate. There were no additional clinical features to suggest an underlying connective tissue disease, and an autoimmune serology was negative. Initial laboratory investigations showed a haemoglobin concentration of 107 g/l, mean corpuscular volume of 104.4 fl, bilirubin concentration of 47 µmol/l, and lactate dehydrogenase 695 U/l. Reticulocyte count was raised at 162.4 (normal range 10-100). IgG and IgA levels were normal. IgM concentration was raised at 3.62 g/l (normal range 0.5-2.0 g/l). Infrared thermography at baseline was normal, but delayed rewarming was apparent after local cold exposure, consistent with Raynaud’s phenomenon (fig 1⇓). Nailfold capillaroscopy was normal. Fig 1  Thermal images (A) at baseline and (B) 10 minutes after local cold challenge ### 1 What would be a more accurate medical description of this patient’s symptoms? #### Short answer This patient’s symptoms would be best described as acrocyanosis. Classic Raynaud’s phenomenon involves triphasic colour changes that include a red-purple phase (representing post-ischaemic hyperaemia), although this stage is not essential for a diagnosis of Raynaud’s phenomenon.1 #### Long answer Raynaud’s phenomenon describes abnormal vascular reactivity, most often after exposure to cold or emotional stress. Raynaud’s phenomenon typically affects the fingers and toes, but can also affect other extremities such as the thumbs, nose, ears, and nipples. Episodes are usually accompanied by colour changes in the …