Dynamic optical coherence tomography of histamine induced wheals

Attempted treatment of primary axillary hyperhidrosis with one session of either Neodymium YAG laser or Intense Pulsed Light: A within patient randomized trial of treated versus untreated contralateral axilla

BACKGROUND

Primary axillary hyperhidrosis (PAH) affects 1-5% of the world's population who has an unmet need for improved treatments. The heating of sweat glands with specific microwave therapy has shown promising results, yet, treatment with widely available devices such as long-pulsed Neodymium Yttrium Aluminum Garnet (Nd:YAG) lasers, diode lasers or Intense Pulsed Light (IPL) may serve as pragmatic alternatives.

OBJECTIVES

To compare sweat secretion of treated versus untreated contralateral control axilla 1-3 months after one session of Nd:YAG laser or IPL in patients with PAH.

METHODS

A within-person randomized controlled trial. Patients were randomized to receive either one session of Nd:YAG laser or IPL in one axilla with the contra-lateral serving as control. Sweat production was assessed by gravimetry, trans-epidermal water loss, hyperhidrosis disease severity scale and dynamic optical coherence tomography. Mixed-effects models were used to handle the within-person design, containing both fixed effect factors (side, group, and subgroup), and random effects (patients), while also adjusting for the level at baseline.

RESULTS

A total of 20 patients were enrolled. At follow-up 1-3 months after treatment, sweat secretion was not affected in the treated axilla when compared to the control axillae (0.01 [95%CI: -0.04 to 0.05]; p = 0.68). In the Nd:YAG subgroup (10 patients), least squares means for sweat secretion was 0.18 mg/5 min in the treated versus 0.15 mg/5 min in the control axilla, respectively, corresponding to a statistically insignificant mean difference of 0.02 mg/5 min (95% CI: -0.06 to 0.11; p = 0.54). In the IPL subgroup (10 patients), sweat secretion was 0.06 mg/5 min in the treated axilla versus 0.07 mg/5 min in the control axilla with a statistically insignificant difference of -0.01 points (95% CI: -0.03 to 0.02; p = 0.46). Likewise, none of the secondary outcomes were significantly affected by treatment. However, both treatments appeared safe and well tolerated with no adverse effects reported at follow-up.

CONCLUSIONS

One treatment with external 1064 nm Nd:YAG laser or 640 nm IPL at commercially available settings, failed to demonstrate clinical benefit in treating PAH, with narrow confidence intervals implying that this was not due to a type-2 error.

Nailfold Microvascular Imaging by Dynamic Optical Coherence Tomography in Systemic Sclerosis: A Case-Controlled Pilot Study

In systemic sclerosis, outcome measures of skin microvasculopathy are needed for both clinical trials and practice. The aim of this study was to determine whether dynamic-optical coherence tomography (D-OCT) is able to provide information on microvasculopathy compared with the current gold standard, nailfold videocapillaroscopy (NVC), in patients with systemic sclerosis. This case-controlled study included (i) 40 patients with systemic sclerosis, classified by NVC pattern in four age- and sex-matched groups (normal/nonspecific, early, active, late); (ii) a fifth group of 10 age- and sex-matched healthy controls. All participants underwent NVC and D-OCT. D-OCT images were compared with the corresponding NVC images. Reliability was assessed. D-OCT images visualized the corresponding NVC patterns. D-OCT microvascular flow density was different across the five NVC pattern groups (P = 0.0114) with a significant trend test (P = 0.0006). Microvascular flow density correlated with the NVC semiquantitative score (r = -0.7, P < 0.0001), number of abnormal shapes/mm (r = ‒0.3, P = 0.0264), and number of capillaries/mm (r = 0.6, P < 0.0001). Reliability was excellent (intraclass correlation coefficient > 0.9). In conclusion, in patients with systemic sclerosis, D-OCT provided qualitative and quantitative information on nailfold microvasculopathy, showing a correlation between microvascular flow density and NVC scores. The development of D-OCT as a standardized imaging technique could provide a quantitative outcome measure in clinical trials and practice.

Imaging Motion: A Comprehensive Review of Optical Coherence Tomography Angiography

Optical coherence tomography (OCT) is a three-dimensional (3-D) optical imaging technology that provides noninvasive, micrometer resolution images of structural interiors within biological samples with an approximately 1 ~ 2 mm penetration depth. Over the last decades, advances in OCT have revolutionized biomedical imaging by demonstrating a potential of optical biopsy in preclinical and clinical settings. Recently, functional OCT imaging has shown a promise as angiography to visualize cell-perfused vasculatures in the tissue bed in vivo without requiring any exogenous contrast agents. This new technology termed OCT angiography (OCTA) possesses a unique imaging capability of delineating tissue morphology and blood or lymphatic vessels down to capillaries at real-time acquisition rates. For the past 10 years since 2007, OCTA has been proven to be a useful tool to identify disorder or dysfunction in tissue microcirculation from both experimental animal studies and clinical studies in ophthalmology and dermatology. In this section, we overview about OCTA including a basic principle of OCTA explained with simple optical physics, and its scan protocols and post-processing algorithms for acquisition of angiography. Then, potential and challenge of OCTA for clinical settings are shown with outcomes of human studies.

Dynamic Optical Coherence Tomography Imaging of Telangiectasia Prior to Intense Pulsed Light Treatment-An Opportunity to Target Treatment?

BACKGROUND AND OBJECTIVES

To investigate whether optical coherence tomography (OCT) could be utilized to characterize blood flow and vessel dimensions of facial telangiectasias before and during consecutive intense pulsed light (IPL) treatment.

STUDY DESIGN/MATERIALS AND METHODS

Dynamic OCT (D-OCT) was used to image telangiectasia immediately before and after, 1-3 days after, and 1 month after IPL treatment. Measurements included vessel width and depth, blood flow, and attenuation. Vessel dimensions at baseline were verified by a blinded observer. Clinical improvement was detected as good, moderate, or none, and adverse effects were registered at 1-month follow-up.

RESULTS

In total, 14 patients with facial telangiectasia were included. At baseline, vessel width was median 0.25 mm (interquartile range [IQR]: 0.19-0.34 mm) with an intra-class coefficient (ICC) of 0.89 (95% confidence interval [CI]: 0.70; 0.97). Vessel depth was 0.30 mm (IQR: 0.25-0.33 mm; ICC: 0.40 [CI: -0.07; 0.75]). Vessel depth increased significantly from baseline to 1-month follow-up (P = 0.008), whereas no significant changes in vessel width, blood flow, or attenuation were detected. Clinical efficacy seemed related to the relation between vessel dimensions and applied energy settings.

CONCLUSIONS

The D-OCT imaging technique demonstrated that facial telangiectasias were found deeper within the skin after one IPL treatment. By characterizing the vessel dimensions and blood flow of telangiectasia, D-OCT may improve efficacy and safety of IPL. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Parametric imaging of attenuation by optical coherence tomography: review of models, methods, and clinical translation

SIGNIFICANCE

Optical coherence tomography (OCT) provides cross-sectional and volumetric images of backscattering from biological tissue that reveal the tissue morphology. The strength of the scattering, characterized by an attenuation coefficient, represents an alternative and complementary tissue optical property, which can be characterized by parametric imaging of the OCT attenuation coefficient. Over the last 15 years, a multitude of studies have been reported seeking to advance methods to determine the OCT attenuation coefficient and developing them toward clinical applications.

AIM

Our review provides an overview of the main models and methods, their assumptions and applicability, together with a survey of preclinical and clinical demonstrations and their translation potential.

RESULTS

The use of the attenuation coefficient, particularly when presented in the form of parametric en face images, is shown to be applicable in various medical fields. Most studies show the promise of the OCT attenuation coefficient in differentiating between tissues of clinical interest but vary widely in approach.

CONCLUSIONS

As a future step, a consensus on the model and method used for the determination of the attenuation coefficient is an important precursor to large-scale studies. With our review, we hope to provide a basis for discussion toward establishing this consensus.

Optical coherence tomography angiography and photoacoustic imaging in dermatology

Optical coherence tomography angiography (OCTA) is a relatively novel functional extension of the widely accepted ophthalmic imaging tool named optical coherence tomography (OCT). Since OCTA's debut in ophthalmology, researchers have also been trying to expand its translational application in dermatology. The ability of OCTA to resolve microvasculature has shown promising results in imaging skin diseases. Meanwhile, photoacoustic imaging (PAI), which uses laser pulse induced ultrasound waves as the signal, has been studied to differentiate human skin layers and to help in skin disease diagnosis. This perspective article gives a short review of OCTA and PAI in the field of photodermatology. After an introduction to the principles of OCTA and PAI, we describe the most updated results of skin disease imaging using these two optical imaging modalities. We also place emphasis on dual modality imaging combining OCTA and photoacoustic tomography (PAT) for dermatological applications. In the end, the challenges and prospects of these two imaging modalities in dermatology are discussed.