Clinical performance of a novel hyperspectral imaging device for cutaneous melanoma and pigmented skin lesions in Caucasian skin.

BACKGROUND: The quest for diagnostic tools for the detection of cutaneous malignant melanoma (cMM) is ongoing. A challenge in cMM care is not overlooking cMM at an early stage, while simultaneously avoiding unnecessary biopsies or excisions of benign pigmented skin lesions (PSLs). A novel hyperspectral imaging (HSI) device is shown to have potential for differentiating equivocal PSLs in Asian skin types. Our objective was to assess the accuracy of the HSI device in distinguishing between cMM and benign PSLs in patients with Caucasian skin types. METHODS: Patients with Caucasian skin types (Fitzpatrick I-II), enrolled for excisional biopsies of PSLs were included and examined using the HSI device. The discrimination index (DI) was used to demonstrate the sensitivity (SE) and specificity (SP) in comparison with the re-evaluated histopathology diagnoses. RESULTS: In 186 patients, 202 pigmented skin lesions were included. The sensitivity to detect cMM was 96.7% (87/90), and the specificity for benign lesions was 42.1% (45/107). The AUC was 0.800 (95% confidence interval (CI): 0.740-0.861). CONCLUSIONS: Our novel HSI device showed a high sensitivity in detecting malignant lesions in patients with Caucasian skin types. Compared with analogous technologies, as multispectral imaging or electrical impedance spectroscopy, our device showed similar or better accuracy in differentiating cMM from benign PSLs. Therefore, it might be a useful clinical tool in skin types I-IV and where further triage of pigmented skin lesions is important.

Automatic diagnosis of melanoma using hyperspectral data and GoogLeNet.

BACKGROUND: Melanoma is a type of superficial tumor. As advanced melanoma has a poor prognosis, early detection and therapy are essential to reduce melanoma-related deaths. To that end, there is a need to develop a quantitative method for diagnosing melanoma. This paper reports the development of such a diagnostic system using hyperspectral data (HSD) and a convolutional neural network, which is a type of machine learning. MATERIALS AND METHODS: HSD were acquired using a hyperspectral imager, which is a type of spectrometer that can simultaneously capture information about wavelength and position. GoogLeNet pre-trained with Imagenet was used to model the convolutional neural network. As many CNNs (including GoogLeNet) have three input channels, the HSD (involving 84 channels) could not be input directly. For that reason, a "Mini Network" layer was added to reduce the number of channels from 84 to 3 just before the GoogLeNet input layer. In total, 619 lesions (including 278 melanoma lesions and 341 non-melanoma lesions) were used for training and evaluation of the network. RESULTS AND CONCLUSION: The system was evaluated by 5-fold cross-validation, and the results indicate sensitivity, specificity, and accuracy of 69.1%, 75.7%, and 72.7% without data augmentation, 72.3%, 81.2%, and 77.2% with data augmentation, respectively. In future work, it is intended to improve the Mini Network and to increase the number of lesions.

Direct chemical evidence for eumelanin pigment from the Jurassic period.

Melanin is a ubiquitous biological pigment found in bacteria, fungi, plants, and animals. It has a diverse range of ecological and biochemical functions, including display, evasion, photoprotection, detoxification, and metal scavenging. To date, evidence of melanin in fossil organisms has relied entirely on indirect morphological and chemical analyses. Here, we apply direct chemical techniques to categorically demonstrate the preservation of eumelanin in two > 160 Ma Jurassic cephalopod ink sacs and to confirm its chemical similarity to the ink of the modern cephalopod, Sepia officinalis. Identification and characterization of degradation-resistant melanin may provide insights into its diverse roles in ancient organisms.

Hyperspectroscopic screening of melanoma on acral volar skin.

BACKGROUND/PURPOSE: Early detection and proper excision of the primary lesions of melanoma are crucial for reducing melanoma-related deaths. To support the early detection of melanoma, automated melanoma-screening systems have been extensively studied and developed. In this article, a previously reported hyperspectral imager and melanoma discrimination index are applied to the discrimination of acral lentiginous melanoma (ALM) from acral nevus (AN), and their diagnostic performance is reported. METHODS: The index expresses the disordered nature of each lesion including variegation in color based on variation in spectral information obtained from each lesion. Performance of the index has been studied in thirteen cases of ALM and seven cases of AN, obtained from patients and volunteers, all of whom were Japanese. RESULTS: The index discriminated ALM from AN with a sensitivity of 92% and a specificity of 86%. The area under the receiver operating characteristic curve was 0.97. CONCLUSION: The performance of the proposed objective melanoma discrimination index at a molecular pigmentary level approached that of clinical experts, using the three-step algorithm as the gold standard.

Independent component analysis of hyperspectral data measured from overlapping latent fingermarks: Forensic potential of independent component images.

Overlapping fingermark images are sometimes discarded because fingermark collation for the individual fingermarks is difficult. Fluorescence hyperspectral data (HSD) measured using the models of double overlapping fingermarks obtained under the excitation of a high-power, continuous wave, green laser is suitable for obtaining individual fingermark images. However, there are limitations such as the problems on each spectrum of the individual fingermark and the forensic value of the obtained images. In this study, independent component analysis (ICA) was applied to the fluorescence HSD obtained from the models of doubly overlapping fingermarks, to obtain independent component (IC) spectra and the corresponding IC images. Forensic value of the obtained IC images was examined, considering the possibility of fingermark collation in masked fashion to the model sample information. The IC images obtained from the HSD had enough potential to enable extracting twelve minutiae required for fingermark collation if the image quality was good.

A possible melanoma discrimination index based on hyperspectral data: a pilot study.

BACKGROUND: Early detection and proper excision of the primary lesions of malignant melanoma (MM) are crucial for reducing melanoma-related deaths. To support the early detection of melanoma, automated melanoma screening systems have been extensively studied and developed. In this article, we present a hyperspectral melanoma screening system and propose a possible melanoma discrimination index derived from the characteristics of the pigment molecules in the skin, both of which have been derived from hyperspectral data (HSD). METHODS: The index expresses the disordered nature of each lesion including variegation in color based on variation in spectral information obtained from each lesion. Performance of the index in discriminating melanomas from other pigmented skin lesions has been studied in five cases of melanoma (41 HSD sets), one case of Spitz nevus (13 HSD sets), 10 cases of seborrheic keratosis (78 HSD sets), three cases of basal cell carcinoma (16 HSD sets), and nine cases of melanocytic nevus (21 HSD sets), obtained from patients and volunteers, all of whom were Japanese. RESULTS: Performance of the index, which reflects the disordered nature of a lesion, discriminates melanomas with a sensitivity of 90%, a specificity of 84%, and an area under the receiver operating characteristic curve of 0.93, on resubstitution. CONCLUSION: An objective melanoma discrimination index at a molecular pigmentary level, derived from HSD, has been proposed, and its performance evaluated. This index was highly successful in discriminating MM from non-melanoma, although the statistical population was small.

Separation of overlapping fingerprints by principal component analysis and multivariate curve resolution-alternating least squares analysis of hyperspectral imaging data.

Overlapping fingerprints are often found at crime scenes, but only individual fingerprints separated from each other are admissible as evidence in court. Fingerprint components differ slightly among individuals, and thus their fluorescence spectra also differ from each other. Therefore, the separation of overlapping fingerprints using the difference of the fluorescence spectrum was performed with a hyperspectral imager. Hyperspectral data (HSD) of overlapping fingerprints were recorded under UV LED excitation. Principal component analysis (PCA) and multivariate curve resolution-alternating least squares (MCR-ALS) were applied to the HSD to determine the optimal method for obtaining high-contrast images of individual fingerprints. The results suggested that MCR-ALS combined with PCA-based initialization is capable of separating overlapping fingerprints into individual fingerprints. In this study, a method for separating overlapping fingerprints without initial parameters was proposed.

Possible oxidative polymerization mechanism of 5,6-dihydroxyindole from ab initio calculations.

The reactivity of 5,6-dihydroxyindole and its major dimers has been studied with the use of a recently proposed general-purpose reactive indicator (Anderson et al. J. Chem. Theory Comput. 2007, 3, 358-374) from ab initio density-functional theory calculations. Theoretical prediction has reasonably explained previously isolated oligomers up to tetramers. The oxidative polymerization is governed by the electron-transfer-controlled reaction. The electrostatic interaction plays a regioselective role in the reactant complex and/or intermediates. A monomer-dimer coupling is able to form trimers, while a part of it is prevented by the exchange repulsion, i.e., steric hindrance. Therefore, a dimer-dimer coupling is also able to form tetramers.

Dynamics of the cell division orientation of granule cell precursors during cerebellar development.

The cerebellar granule cell (GC) system provides a good model for studying neuronal development. In the external granule layer (EGL), granule cell precursors (GCPs) rapidly and continuously divide to produce numerous GCs as well as GCPs. In some brain regions, the orientation of cell division affects daughter cell fate, thus the direction of GCP division is related to whether it produces a GCP or a GC. Therefore, we tried to characterize the orientation of GCP division from embryonic to postnatal stages and to identify an environmental cue that regulates the orientation. By visualizing chromatin in EGL GCPs at M-phase, we found that the directions of cell divisions were not random but dynamically regulated during development. While horizontal and vertical divisions were equivalently observed in embryos, horizontal division was more frequently observed at early postnatal stages. Vertical division became dominant at late cerebellar developmental stages. Administration of a SHH inhibitor to cultured cerebellar slices resulted in randomized orientation of cell division, suggesting that SHH signaling regulates the direction of cell division. These results provide fundamental data towards understanding the development of GCs.

Conformational properties of and a reorientation triggered by sugar-water vibrational resonance in the hydroxymethyl group in hydrated beta-glucopyranose.

In this paper, we discuss the conformational properties of the hydroxymethyl group of beta-glucopyranose in aqueous solution and its reorientation mechanism. First, using the values for the hydroxymethyl torsion (O5-C5-C6-O6) angle obtained by our ab initio simulations, we reestimate the experimental ratio of the hydroxymethyl rotamer populations. The reestimated ratio is found to be in agreement with those previously reported in several computational studies, which probably partly explains the discrepancies between theoretical and experimental studies that have been discussed in the literature. Second, our time-frequency analysis on a reorientation in the hydroxymethyl group in an ab initio molecular dynamics trajectory suggests that, before the reorientation, the O6-H6 stretching mode is vibrationally coupled with a proton-accepting first-hydration-shell water molecule, whereas the C6-O6 stretching mode is vibrationally coupled with a proton-donating one. The amount of the total vibrational energy induced by these vibrational couplings is estimated to be comparable to typical values for the potential barriers between hydroxymethyl rotamers. To elucidate the vibrational couplings, we investigate the hydrogen-bonding properties around the hydroxymethyl group during the pretransition period. The implications, validity, and limitation of a possible reorientation mechanism based on these findings are also discussed.

Circular hydrogen bond networks on the surface of beta-ribofuranose in aqueous solution.

This paper examines the hydration structure on the surface of beta-ribofuranose in aqueous solution, using the ab initio molecular dynamics method. In particular, we focus on circular hydrogen bond networks involving two ribofuranose oxygens and three water molecules. In our simulations, the circular hydrogen bond networks near the ring oxygen of beta-ribofuranose are found to be significantly influenced by the orientation of the hydroxymethyl group. The arrangements of hydrogen bonds observed in the circular hydrogen bond networks are both homodromic and antidromic. To explain these observations, we analyze the electronic properties of the first-hydration-shell water molecules and the OH groups of beta-ribofuranose, using the centers of their maximally localized Wannier functions. The dipole moments of the proton-accepting first-hydration-shell water molecules in our well-defined circular hydrogen bond networks are found to increase by about 0.3 D compared with that of liquid water, indicating the relatively strong polarization effects created by the interactions between the OH groups of the solute and the surrounding water molecules. Our analysis also implies that circular H-bond networks cannot be fully explained from a simple geometrical point of view.

Structural fluctuation and dynamics of ribose puckering in aqueous solution from first principles.

Using the method of ab initio molecular dynamics, we examine the structural fluctuation and the low-frequency dynamics of beta-ribofuranose puckering in aqueous solution. Our analysis suggests that the distance between the anomeric and hydroxymethyl oxygens is a simple relevant geometrical parameter that dynamically correlates with the phase angle in the north region. The time-frequency analysis using the Hilbert-Huang transform also confirms the correlation, and most of the instantaneous frequencies for the phase angle and the above distance are found to be concentrated on the region below about 100 cm(-1). Our analysis of ab initio molecular dynamics trajectories suggests that the molecular origin of the hydration effects on the low-frequency dynamics of beta-ribofuranose puckering is closely related to this correlation and thus primarily attributed to the relatively local interactions among the anomeric and hydroxymethyl oxygens and the surrounding water molecules near them. Additionally, we discuss the difference in the low-frequency dynamics of beta-ribofuranose puckering between two hydroxymethyl rotamers.

Noninvasive diagnostics supporting system for choroidal melanoma: a pilot study.

PURPOSE: To examine the usefulness of a near-infrared hyperspectral imager (NIR-HSI) system in discriminating uveal melanoma from other intraocular tumors. METHOD: The NIR-HSI, which had been developed as a screening system for age-related macular degeneration, was used to measure near-infrared hyperspectral data (NIR-HSD) of a lesion located at the ocular fundus of 17 Japanese patients, including 5 with choroidal melanoma and 12 with other intraocular tumors. The index was derived from each NIR-HSD. Non-parametric statistical analysis was performed. RESULTS: Diagnostic accuracy of 94.1% was achieved when the threshold value of the index was set to minimize the average value of false-positive and -negative fractions. CONCLUSIONS: The NIR-HSI system is useful as a noninvasive diagnostic supporting system for choroidal melanoma.

Portable hyperspectral imager with continuous wave green laser for identification and detection of untreated latent fingerprints on walls.

Untreated latent fingerprints are known to exhibit fluorescence under UV laser excitation. Previously, the hyperspectral imager (HSI) has been primarily evaluated in terms of its potential to enhance the sensitivity of latent fingerprint detection following treatment by conventional chemical methods in the forensic science field. In this study however, the potential usability of the HSI for the visualization and detection of untreated latent fingerprints by measuring their inherent fluorescence under continuous wave (CW) visible laser excitation was examined. Its potential to undertake spectral separation of overlapped fingerprints was also evaluated. The excitation wavelength dependence of fluorescent images was examined using an untreated palm print on a steel based wall, and it was found that green laser excitation is superior to blue and yellow lasers' excitation for the production of high contrast fluorescence images. In addition, a spectral separation method for overlapped fingerprints/palm prints on a plaster wall was proposed using new images converted by the division and subtraction of two single wavelength images constructed based on measured hyperspectral data (HSD). In practical tests, the relative isolation of two overlapped fingerprints/palm prints was successful in twelve out of seventeen cases. Only one fingerprint/palm print was extracted for an additional three cases. These results revealed that the feasibility of overlapped fingerprint/palm print spectral separation depends on the difference in the temporal degeneration of each fluorescence spectrum. The present results demonstrate that a combination of a portable HSI and CW green laser has considerable potential for the identification and detection of untreated latent fingerprints/palm prints on the walls under study, while the use of HSD makes it practically possible for doubly overlapped fingerprints/palm prints to be separated spectrally.

Degree of polymerization of 5,6-dihydroxyindole-derived eumelanin from chemical degradation study.

Eumelanin is a brown-black pigment comprising 5,6-dihydroxyindole (DHI) and its 2-carboxy derivative (DHICA), but the detailed structure of eumelanin is unclear. Chemical degradation is a powerful tool for analyzing melanin. H2 O2 oxidation degradation of eumelanin affords pyrrole-2,3,5-tricarboxylic acid (PTCA) and pyrrole-2,3-dicarboxylic acid (PDCA). The ratio of PDCA to PTCA provides information about the eumelanin structure. In this article, we propose simple equations on the basis of previous experimental results on dimer yields for evaluating the yields of PTCA and PDCA from any DHI oligomers. Assuming the chemical disorder model of DHI-melanin, we solve an equation where a theoretical expression for the ratio of PDCA to PTCA is set to the corresponding experimental value to obtain a plausible Poisson distribution of DHI oligomers. The results demonstrate that the main contributors to DHI-melanin are tetramers and pentamers as shown by the mass spectrometry.

Automated evaluation system of dermoscopic images of longitudinal melanonychia: proposition of a discrimination index for detecting early nail apparatus melanoma.

The prognosis of nail apparatus melanoma is generally poor because of difficulty in early stage diagnosis. Most nail apparatus melanomas occur as longitudinal melanonychia, and criteria and algorithms for dermoscopy diagnosis of longitudinal melanonychia have only recently been proposed. However, as with any clinical diagnosis, the diagnosis based on dermoscopy is to some extent subjective. Our goal is to develop an automated dermoscopic screening system for longitudinal melanonychia and to propose a novel objective and quantitative index for discriminating early nail apparatus melanoma from benign longitudinal melanonychia including melanocytic nevus. We propose an automatically calculated index representing degrees of color variegation in dermoscopic images of longitudinal melanonychia. Dermoscopy images of six cases of early stage nail apparatus melanoma and 25 cases of benign longitudinal melanonychia were analyzed with our screening system and a threshold of melanoma discrimination index was determined. This single melanoma discrimination index diagnosed early nail apparatus melanoma with 100% sensitivity and 92% specificity. The automatically calculated index proposed in the present study is valuable for managing longitudinal melanonychia. The results suggest that the degree of color variegation is essentially different between early nail apparatus melanoma and benign longitudinal melanonychia including melanocytic nevus of the nail apparatus.

Novel automated screening of age-related macular degeneration.

PURPOSE: To determine the objective and quantitative hyperspectral parameters for distinguishing between age-related macular degeneration (AMD) and a normal macula. METHODS: Near-infrared hyperspectral images were taken of 71 eyes of 62 AMD patients with exudative AMD and 21 eyes of 12 control subjects without AMD. The spatial information included a 480 × 321-pixel image in a 50° field located at the ocular fundus and a 720-950-nm-per-pixel reflectance spectrum. Macular vectors were determined as the average spectrum for each macula, and reference vectors were used as average macular vectors for healthy volunteers. Variations in vector length and angle were calculated based on comparison with the reference vector. The AMD differentiation index was a parameter that minimized the plot overlap between AMD patients and controls. RESULTS: Statistically significant differences between the AMD patients and controls were noted. Receiver-operating characteristic curve analysis revealed an area under the curve of 0.888. The appropriate threshold values were attained for the proposed discrimination index, including 68 % sensitivity, 95 % specificity and 74 % accuracy. CONCLUSIONS: This study presents a simplified diagnostic index for the determination of age-related macular degeneration based on near-infrared spectra.