Comparing 3D imaging devices for the measurement of cutaneous neurofibromas in patients with Neurofibromatosis Type 1.

BACKGROUND: Cutaneous neurofibromas (cNFs) are a major cause of disfigurement in patients with Neurofibromatosis Type 1 (NF1). However, clinical trials investigating cNF treatments lack standardised outcome measures to objectively evaluate changes in cNF size and appearance. 3D imaging has been proposed as an objective standardised outcome measure however various systems exist with different features that affect useability in clinical settings. The aim of this study was to compare the accuracy, precision, feasibility, reliability and accessibility of three imaging systems. MATERIALS AND METHODS: We compared the Vectra-H1, LifeViz-Micro and Cherry-Imaging systems. A total of 58 cNFs from 13 participants with NF1 were selected for imaging and analysis. The primary endpoint was accuracy as measured by comparison of measurements between imaging systems. Secondary endpoints included reliability between two operators, precision as measured with the average coefficient of variation, feasibility as determined by time to capture and analyse an image and accessibility as determined by cost. RESULTS: There was no significant difference in accuracy between the three devices for length or surface area measurements (p > 0.05), and reliability and precision were similar. Volume measurements demonstrated the most variability compared to other measurements; LifeViz-Micro demonstrated the least measurement variability for surface area and image capture and analysis were fastest with LifeViz-Micro. LifeViz-Micro was better for imaging smaller number of cNFs (1-3), Vectra-H1 better for larger areas and Cherry for uneven surfaces. CONCLUSIONS: All systems demonstrated excellent reliability but possess distinct advantages and limitations. Surface area is the most consistent and reliable parameter for measuring cNF size in clinical trials.

The effect of α-actinin-3 deficiency on muscle aging.

Deficiency of the fast-twitch muscle protein α-actinin-3 due to homozygosity for a nonsense polymorphism (R577X) in the ACTN3 gene is common in humans. α-Actinin-3 deficiency (XX) is associated with reduced muscle strength/power and enhanced endurance performance in elite athletes and in the general population. The association between R577X and loss in muscle mass and function (sarcopenia) has previously been investigated in a number of studies in elderly humans. The majority of studies report loss of ACTN3 genotype association with muscle traits in the elderly, however, there is some indication that the XX genotype may be associated with faster muscle function decline. To further explore these potential age-related effects and the underlying mechanisms, we examined the effect of α-actinin-3 deficiency in aging male and female Actn3 knockout (KO) mice (2, 6, 12, and 18 months). Our findings support previous reports of a diminished influence of ACTN3 genotype on muscle performance in the elderly: genotype differences in intrinsic exercise performance, fast muscle force generation and male muscle mass were lost in aged mice, but were maintained for other muscle function traits such as grip strength. The loss of genotype difference in exercise performance occurred despite the maintenance of some "slower" muscle characteristics in KO muscles, such as increased oxidative metabolism and greater force recovery after fatigue. Interestingly, muscle mass decline in aged 18 month old male KO mice was greater compared to wild-type controls (WT) (-12.2% in KO; -6.5% in WT). These results provide further support that α-actinin-3 deficient individuals may experience faster decline in muscle function with increasing age.