Visualization of intradermal blood vessel structures by dual-wavelength photoacoustic microscopy and characterization of three-dimensional construction of livedo-racemosa in cutaneous polyarteritis nodosa

BACKGROUND

Photoacoustic microscopy is expected to have clinical applications as a noninvasive and three-dimensional (3D) method of observing intradermal structures.

OBJECTIVE

Investigate the applicability of a photoacoustic microscope equipped with two types of pulsed lasers that can simultaneously recognize hemoglobin and melanin.

METHODS

16 skin lesions including erythema, pigmented lesions, vitiligo and purpura, were analyzed to visualize 3D structure of melanin granule distribution and dermal blood vessels. 13 cases of livedo racemosa in cutaneous polyarteritis nodosa (cPN) were further analyzed to visualize the 3D structure of dermal blood vessels in detail. Vascular structure was also analyzed in the biopsy specimens obtained from tender indurated erythema of cPN by CD34 immunostaining.

RESULTS

Hemoglobin-recognition signal clearly visualized the 3D structure of dermal blood vessels and melanin-recognition signal was consistently reduced in vitiligo. In livedo racemosa, the hemoglobin-recognition signal revealed a relatively thick and large reticular structure in the deeper layers that became denser and finer toward the upper layers. The numerical analysis revealed that the number of dermal blood vessels was 1.29-fold higher (p<0.05) in the deeper region of the lesion than that of normal skin. The CD34 immunohistochemical analysis in tender indurated erythema revealed an increased number of dermal vessels compared with normal skin in 88.9% (8/9) of the cases, suggesting that vascular network remodeling had occurred in cPN.

CONCLUSION

The photoacoustic system has an advantage in noninvasively detecting dermal blood vessel structures that are difficult to recognize by two-dimensional histopathology specimen examination and is worth evaluating in various skin diseases.

Quantitative analysis of age-related changes in vascular structure, oxygen saturation, and epidermal melanin structure using photoacoustic methods

BACKGROUND

Vascular structure, blood oxygen saturation, and melanin status of the epidermis are chromophore factors related to light absorption. Therefore, they are likely to be related to skin appearance. Thus, it is important to measure these internal skin features and understand their characteristics. Thus, we aimed to analyze the individual differences and aging changes in the skin by measuring the internal skin characteristics, such as vascular structure, oxygen saturation, and the 3D distribution of melanin in the epidermis, using a noninvasive photoacoustic (PA) measurement method.

MATERIALS AND METHODS

A PA measurement device was used as a noninvasive measurement method. Eighty Japanese women aged between 20 and 60 years were enrolled. The target area was the buccal region of the face.

RESULTS

The blood vessel structure showed a decrease in fine vessels with age, with a stronger tendency observed in the dermis layer, and the volume of blood vessels was larger in the dermis layer than in the dermal-subcutaneous fat boundary layer. Oxygen saturation showed a similar decreasing trend with age in all depths examined. Melanin condition as the torus-like pattern structure tended to increase with age.

CONCLUSION

PA measurements revealed the characteristics of several chromophores, providing a new skin aging mechanism.

Burn depth assessments by photoacoustic imaging and laser Doppler imaging

Diagnosis of burn depths is crucial to determine the treatment plan for severe burn patients. However, an objective method for burn depth assessment has yet to be established, although a commercial laser Doppler imaging (LDI) system is used limitedly. We previously proposed burn depth assessment based on photoacoustic imaging (PAI), in which thermoelastic waves originating from blood under the burned tissue are detected, and we showed the validity of the method by experiments using rat models with three different burn depths: superficial dermal burn, deep dermal burn and deep burn. On the basis of those results, we recently developed a real-time PAI system for clinical burn diagnosis. Before starting a clinical trial, however, there is a need to reveal more detailed diagnostic characteristics, such as linearity and error, of the PAI system as well as to compare its characteristics with those of an LDI system. In this study, we prepared rat models with burns induced at six different temperatures from 70 to 98 °C, which showed a linear dependence of injury depth on the temperature. Using these models, we examined correlations of signals obtained by PAI and LDI with histologically determined injury depths and burn induction temperatures at 48 hours postburn. We found that the burn depths indicated by PAI were highly correlative with histologically determined injury depths (depths of viable vessels) as well as with burn induction temperatures. Perfusion values measured by LDI were less correlative with these parameters, especially for burns induced at higher temperatures, being attributable to the limited detectable depth for light involving a Doppler shift in tissue. In addition, the measurement errors in PAI were smaller than those in LDI. On the basis of these results, we will be able to start clinical studies using the present PAI system.

An unusual association of monoclonal gammopathy, paroxysmal nocturnal haemoglobinuria and myelodysplastic syndrome transformed into acute myeloid leukaemia: coexistence of triple clonal disorders

An unusual association of paroxysmal nocturnal haemoglobinuria (PNH), myelodysplastic syndrome (MDS), acute myeloid leukaemia (AML) and monoclonal gammopathy is reported. A 60-year old male, who had a history of IgA monoclonal gammopathy, presented with haemoglobinuria and colic pain. Flow cytometry showed CD55negative/59dim peripheral red cells, and bone marrow examination disclosed MDS. Eleven months, he developed later AML with disappearance of the PNH clones, although the monoclonal gammopathy persisted. The relationship between PNH and MDS has not fully been assessed, although our findings indicate that these triple clonal disorders, all coexisted in one patient.