Optical devices used for image analysis of pigmented skin lesions: a proposal for quality assurance protocol using tissue-like phantoms

Insertable Biosensors: Combining Implanted Sensing Materials with Wearable Monitors

Insertable biosensor systems are medical diagnostic devices with two primary components: an implantable biosensor within the body and a wearable monitor that can remotely interrogate the biosensor from outside the body. Because the biosensor does not require a physical connection to the electronic monitor, insertable biosensor systems promise improved patient comfort, reduced inflammation and infection risk, and extended operational lifetimes relative to established percutaneous biosensor systems. However, the lack of physical connection also presents technical challenges that have necessitated new innovations in developing sensing chemistries, transduction methods, and communication modalities. In this review, we discuss the key developments that have made insertables a promising option for longitudinal biometric monitoring and highlight the essential needs and existing development challenges to realizing the next generation of insertables for extended-use diagnostic and prognostic devices.

Objective Spectrometric Measurement of Keloid Color in the East Asian Population: Pitfalls of Subjective Color Measurements

BACKGROUND

Keloids are characterized by the formation of excessive scar tissue that extends beyond the area of the initial wound. Keloid redness is due to angiogenesis and chronic inflammation and is an important indicator of the severity of the lesion and the effectiveness of treatment.

METHODS

The color of 33 untreated keloids from 30 patients was measured with a narrow-band reflectance colorimeter. The erythema and melanin levels in the keloids (Ek and Mk, respectively) were recorded with control data obtained from the flexor aspect of the forearm (Ec and Mc, respectively). The keloid color was also evaluated subjectively.

RESULTS

The Ek or Mk values did not vary significantly according to symptom intensity, scar region, patient age, and patient sex. Younger patients (<40 years) and female patients had significantly higher Ek/Ec ratios than did older patients and male patients, respectively. Subjective keloid redness evaluations distinguished keloids with high Ek/Ec ratios from keloids with low Ek/Ec ratios (P<0.0001) but could not distinguish keloids with high Ek from keloids with low Ek.

CONCLUSIONS

Subjective evaluations of keloids in Japanese subjects reflected Ek/Ec ratios, which were strongly affected by variation in background skin color. The subjective assessment of the color of keloids or other skin disorders should be performed with caution in Asian populations.

Fiber-optic and articulating arm implementations of laminar optical tomography for clinical applications

Laminar optical tomography (LOT) is a recently developed technique for depth-resolved in vivo imaging of absorption and fluorescence contrast. Until now, LOT has been implemented in a benchtop configuration, limiting accessibility to tissues and restricting imaging applications. Here we report on LOT implemented through an articulating arm and a fiber optic image bundle allowing flexible imaging for a range of clinical applications. We quantify the performance of these two implementations by imaging a tissue mimicking phantom.

Comparing the effectiveness of Q-switched Ruby laser treatment with that of Q-switched Nd:YAG laser for oculodermal melanosis (Nevus of Ota)

BACKGROUND AND OBJECTIVE

The objective of this study was to compare the efficacy and safety of Q-switched Ruby laser versus Q-switched neodymium:yttrium-aluminium-garnet (Nd:YAG) laser for oculodermal melanosis (Nevus of Ota) birthmarks in a large group of patients.

STUDY DESIGN/MATERIALS AND METHODS

A retrospective review was conducted of 94 patients with Nevus of Ota treated with a Q-switched Ruby laser and a Q-switched Nd:YAG laser over a 3-year period. The subjects' ages ranged from 3 to 64 years; there were 70 females and 24 males, all of whom were of Asian descent. The number of treatments ranged from 1 to 8. Duration of treatment ranged from 6 months to 3 years and 10 months, with a mean of 14 months. Patients (n=47) received Q-switched Ruby laser treatment (694 nm) using light dosages of 7-10 J cm(-2). Subsequent patients (n=47) received Q-switched Nd:YAG laser treatment (1064 nm) using light dosages of 7-10 J cm(-2). The primary efficacy measurement was the quantitative assessment of clearing and fading response using the DermaSpectrometer for the Q-switched Ruby laser group versus the Q-switched Nd:YAG laser group.

RESULTS

Based on a paired t-test, clinical and statistically significant differences in clearing and fading response were observed amongst the Q-switched Ruby laser-treated subjects as preferred to the appearance of Q-switched Nd:YAG laser-treated group (P<0.05). In both groups, transient hyperpigmentation resolved in all subjects within 6 months. Permanent hyperpigmentation or scarring was not observed in either group.

CONCLUSION

Use of a Q-switched Ruby laser resulted in better clearing and fading as compared with Q-switched Nd:YAG laser.

Simultaneous multiwavelength laminar optical tomography

Spatially resolved reflectance measurements can be used to characterize the depth-resolved optical properties of superficial tissues. However, until now, rapid acquisition of multiwavelength data has been hindered by multiplexing problems. We report on a novel multiwavelength laminar optical tomography system capable of acquiring data from multiple source-detector separations at three wavelengths simultaneously. Such data can allow in vivo depth-resolved spectroscopic imaging of absorbers, such as oxy- and deoxyhemoglobin, or of multiple fluorophores, that is unaffected by motion artifacts at frame rates exceeding 100 Hz. The system design and phantom validation studies are presented.

Methodology of a real-time quality control for the multispectral digital colposcope (MDC)

BACKGROUND

The diagnostic ability of algorithms developed for the Multispectral Digital Colposcope (MDC) is highly dependent on the quality of the image. The field of objective medical image quality analysis has great potential but has not been well exploited. Various researchers have reported different measures of image quality but with an existence of a reference image. The quality of an image can be attributed to several sources of errors, a few of which would be inclusion of presence of extraneous components, improper illumination, or an image out of focus. This can be due to motion artifact or the region of interest out of the focal plane.

METHODS

With spectroscopic measurements, assessment of data quality has been used by our group in the past to avoid hardware errors at the time of acquisition. We are currently developing algorithms that will help identify hardware and acquisition errors to the clinician in under a few seconds.

RESULTS

Minimizing these errors not only provides quality images for a diagnostic algorithm, but reduces the necessity for complex and time intensive post-processing software for enhancing the images.

CONCLUSION

We propose a no reference image quality system specifically designed for MDC that can be modified to similar spectroscopic imaging applications.