State of the Art on Nailfold Capillaroscopy
State of the Art on Nailfold Capillaroscopy
While NVC measures capillary morphology, methods such as laser Doppler imaging and thermography can be used to measure cutaneous blood vessel function, e.g. blood flow. Notably, the signal arising from the aforementioned functional measurements of blood flow is from more than just the capillary bed. In this way thermography reports skin temperature, representative of underlying blood flow, with both muscle and skin perfusion believed to contribute to the signal. Laser Doppler measures not only superficial capillary blood flow but also the arterial and venous vessels of the superficial and mid-dermis.
This functional analysis has been used to discriminate PRP from SRP and has been linked to morphological analysis (capillaroscopy) within SSc populations.
In patients with RP, a study comparing various non-invasive methods for distinguishing patients with SRP due to SSc from those with PRP and healthy controls reported that laser Doppler imaging and thermography yielded correct classification rates of 72% and 74%, respectively, on the basis of blood vessel function.
However, NVC was found to be the superior discriminator with a rate of correct disease classification of 89%. A combination of all three techniques increased the rate of correct classification from 89% to 94%, but did not improve the sensitivity.
Interestingly, also other, less common combinations, such as the combination of laser Doppler and photoplethysmography (an optical measurement technique), both assessing flow in the microvascular bed, may be useful in the characterization of PRP from SRP due to SSc.
In patients with SSc, a correlation between morphological evaluation and functional evaluation (at baseline and after application of a stimulus) has been established. In this way correlations between microangiopathy (as assessed by capillaroscopy) and blood flow (as assessed by laser Doppler, measuring blood flow over a certain point) both at baseline temperature and after heat stimulus (R = −0.5 and −0.7) have been described.
Moreover, SSc patients showing the late NVC pattern of microangiopathy have been shown to display significantly lower blood flow on laser Doppler flowmetry at baseline temperature and after heat stimulus than patients with active and early NVC patterns (P = 0.05/0.03) and (P = 0.07/0.05). This association has also been shown using a new laser device, laser speckle contrast imaging (LASCA), which measures perfusion distribution over an area. The topic deserves further study.
Correlations Between Morphological Analysis of Microcirculation (Capillaroscopy) and Functional Analysis of Microcirculation
While NVC measures capillary morphology, methods such as laser Doppler imaging and thermography can be used to measure cutaneous blood vessel function, e.g. blood flow. Notably, the signal arising from the aforementioned functional measurements of blood flow is from more than just the capillary bed. In this way thermography reports skin temperature, representative of underlying blood flow, with both muscle and skin perfusion believed to contribute to the signal. Laser Doppler measures not only superficial capillary blood flow but also the arterial and venous vessels of the superficial and mid-dermis.
This functional analysis has been used to discriminate PRP from SRP and has been linked to morphological analysis (capillaroscopy) within SSc populations.
In patients with RP, a study comparing various non-invasive methods for distinguishing patients with SRP due to SSc from those with PRP and healthy controls reported that laser Doppler imaging and thermography yielded correct classification rates of 72% and 74%, respectively, on the basis of blood vessel function.
However, NVC was found to be the superior discriminator with a rate of correct disease classification of 89%. A combination of all three techniques increased the rate of correct classification from 89% to 94%, but did not improve the sensitivity.
Interestingly, also other, less common combinations, such as the combination of laser Doppler and photoplethysmography (an optical measurement technique), both assessing flow in the microvascular bed, may be useful in the characterization of PRP from SRP due to SSc.
In patients with SSc, a correlation between morphological evaluation and functional evaluation (at baseline and after application of a stimulus) has been established. In this way correlations between microangiopathy (as assessed by capillaroscopy) and blood flow (as assessed by laser Doppler, measuring blood flow over a certain point) both at baseline temperature and after heat stimulus (R = −0.5 and −0.7) have been described.
Moreover, SSc patients showing the late NVC pattern of microangiopathy have been shown to display significantly lower blood flow on laser Doppler flowmetry at baseline temperature and after heat stimulus than patients with active and early NVC patterns (P = 0.05/0.03) and (P = 0.07/0.05). This association has also been shown using a new laser device, laser speckle contrast imaging (LASCA), which measures perfusion distribution over an area. The topic deserves further study.
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