Colour differences in Caucasian and Oriental women's faces illuminated by white light-emitting diode sources

OBJECTIVE

To provide an approach to facial contrast, analysing CIELAB colour differences (ΔEab,10∗) and its components in women's faces from two different ethnic groups, illuminated by modern white light-emitting diodes (LEDs) or traditional illuminants recommended by the International Commission on Illumination (CIE).

METHODS

We performed spectrophotometric measurements of spectral reflectance factors on forehead and cheek of 87 young healthy women (50 Caucasians and 37 Orientals), plus five commercial red lipsticks. We considered a set of 10 white LED illuminants, representative of technologies currently available on the market, plus eight main illuminants currently recommended by the CIE, representative of conventional incandescent, daylight and fluorescent light sources. Under each of these 18 illuminants, we analysed the magnitude and components of ΔEab,10∗ between Caucasian and Oriental women (considering cheek and forehead), as well as for cheek-forehead and cheek-lipsticks in Caucasian and Oriental women. Colour-inconstancy indices for cheek, forehead and lipsticks were computed, assuming D65 and A as reference illuminants.

RESULTS

ΔEab,10∗ between forehead and cheek were quantitatively and qualitatively different in Orientals and Caucasians, but discrepancies with respect to average values for 18 illuminants were small (1.5% and 5.0% for Orientals and Caucasians, respectively). ΔEab,10∗ between Caucasians and Orientals were also quantitatively and qualitatively different both for forehead and cheek, and discrepancies with respect to average values were again small (1.0% and 3.9% for forehead and cheek, respectively). ΔEab,10∗ between lipsticks and cheek were at least two times higher than those between forehead and cheek. Regarding ΔEab,10∗ between lipsticks and cheeks, discrepancies with respect to average values were in the range 1.5-12.3%, although higher values of up to 54.2% were found for a white RGB LED. This white RGB LED provided the highest average colour-inconstancy indices: 17.1 and 11.5 CIELAB units, under reference illuminants D65 and A, respectively.

CONCLUSION

Colour contrasts in women's faces under CIE standard illuminants for outdoor and indoor conditions may be strongly altered using specific white LEDs. More research needs to be performed on the impact of spectral power distribution of light sources with high colour rendering indices on visual colour appearance of cosmetic products.

Interest of [(18)F]fluorodeoxyglucose positron emission tomography/computed tomography for the diagnosis of relapse in patients with spinal infection: a prospective study

Relapse after treatment of a spinal infection is infrequent and difficult to diagnose. The aim of this study was to assess the diagnostic performance of [(18)F]fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) in this setting. Thirty patients (21 men, nine women; median age 61.2 years) with a suspected spinal infection relapse were prospectively included between March 2010 and June 2013. The initial diagnosis of spinal infection was confirmed by positive bacterial cultures. The patients underwent [(18)F]FDG PET/CT and magnetic resonance imaging (MRI) 1 month after antibiotic treatment interruption. PET/CT data were interpreted both visually and semi-quantitatively (SUVmax). The patients were followed for ≥12 months and the final diagnosis of relapse was based on new microbiological cultures. Seven patients relapsed during follow up. Sensitivity, specificity, positive predictive value and negative predictive value were 66.6%, 61.9%, 33.3% and 86.6%, respectively for MRI and 85.7, 82.6, 60.0 and 95.0 for PET/CT. Although these values were higher for PET/CT than for MRI, the difference was not statistically significant (p=0.3). [(18)F]FDG PET/CT may be useful for diagnosing a relapse of spinal infections, in particular if metallic implants limit the performance of MRI.

Potential of [18F]-fluoromisonidazole positron-emission tomography for radiotherapy planning in head and neck squamous cell carcinomas

BACKGROUND AND PURPOSE

Positron-emission tomography (PET) with [(18)F]-fluoromisonidazole (FMISO) permits consideration of radiotherapy dose escalation to hypoxic volumes in head and neck cancers (HNC). However, the definition of FMISO volumes remains problematic. The aims of this study are to confirm that delayed acquisition at 4 h is most appropriate for FMISO-PET imaging and to assess different methods of volume segmentation.

PATIENTS AND METHODS

A total of 15 HNC patients underwent several FMISO-PET/computed tomography (CT) acquisitions 2, 3 and 4 h after FMISO injection. Three automatic methods of PET image segmentation were tested: fixed threshold, adaptive threshold based on the ratio between tumour-derived and background activities (R(T/B)) and the fuzzy locally adaptive Bayesian (FLAB) method. The hypoxic fraction (HF), which is defined as the ratio between the FMISO and CT volumes, was also calculated.

RESULTS

The R(T/B) for images acquired at 2, 3 and 4 h differed significantly, with mean values of 2.5 (1.7-2.9), 3 (2-4.5) and 3.4 (2.3-6.1), respectively. The mean tumour volume, as defined manually using CT images, was 39.1 ml (1.2-116 ml). After 4 h, the mean FMISO volumes were 18.9 (0.1-81), 9.5 (0.9-33.1) and 12.5 ml (0.9-38.4 ml) with fixed threshold, adaptive threshold and the FLAB method, respectively; median HF values were 0.47 (0.1-1.93), 0.25 (0.11-0.75) and 0.35 (0.14-1.05), respectively. FMISO volumes were significantly different.

CONCLUSION

The best contrast is obtained at the 4-hour acquisition time. Large discrepancies were found between the three tested methods of volume segmentation.

Experimental determination of a procedure for casting a solid coloured emulsion

The aim of this study was to determine the experimental procedure for casting a solid water/oil (W/O) emulsion foundation. This process will enable us to preserve the organoleptic qualities of the foundation (hardness, surface appearance and cosmetic sensation) as well as maintaining the percentage of water contained in the formula. Two different industrial parameters were studied: * Influence of the temperature used to cast the bulk in the mould. * Influence of the type of cooling used for the mould, once full. For each trial, the hardness and the melting point were measured. The optimum results for this process were as follows: * Casting temperature: 65 degrees C. * Cooling temperature: 4 degrees C.