Background: Radiopaque breast markers cause artifacts in dedicated spiral breast-computed tomography (SBCT). This study investigates the extent of artifacts in different marker types and the... Show moreBackground: Radiopaque breast markers cause artifacts in dedicated spiral breast-computed tomography (SBCT). This study investigates the extent of artifacts in different marker types and the feasibility of reducing artifacts through a metal artifact reduction (MAR) algorithm. Methods: The pilot study included 18 women who underwent contrast-enhanced SBCT. In total, 20 markers of 4 different types were analyzed for artifacts. The extent of artifacts with and without MAR was measured via the consensus of two readers. Image noise was quantitatively evaluated, and the effect of MAR on the detectability of breast lesions was evaluated on a 3-point Likert scale. Results: Breast markers caused significant artifacts that impaired image quality and the detectability of lesions. MAR decreased artifact size in all analyzed cases, even in cases with multiple markers in a single slice. The median length of in-plain artifacts significantly decreased from 31 mm (range 11-51 mm) in uncorrected to 2 mm (range 1-5 mm) in corrected images (p <= 0.05). Artifact size was dependent on marker size. Image noise in slices affected by artifacts was significantly lower in corrected (13.6 +/- 2.2 HU) than in uncorrected images (19.2 +/- 6.8 HU, p <= 0.05). MAR improved the detectability of lesions affected by artifacts in 5 out of 11 cases. Conclusion: MAR is feasible in SBCT and improves the image quality and detectability of lesions. Show less
Longitudinal bone growth is regulated in the growth plate. At the end of puberty, growth velocity diminishes and eventually ceases with the fusion of the growth plate through mechanisms that are... Show moreLongitudinal bone growth is regulated in the growth plate. At the end of puberty, growth velocity diminishes and eventually ceases with the fusion of the growth plate through mechanisms that are not yet completely understood. Vascular endothelial growth factor (VEGF) has an important role in angiogenesis, but also in chondrocyte differentiation, chondrocyte survival, and the final stages of endochondral ossification. Estrogens have been shown to up-regulate VEGF expression in the uterus and bone of rats. In this study, we investigated the relation between estrogens and VEGF production in growth plate chondrocytes both in vivo and in vitro. The expression of VEGF protein was down-regulated upon ovariectomy and was restored upon estradiol (E-2) supplementation in rat growth plates. In cultured rat chondrocyte cell line RCJ3.1C5.18, E-2 dose dependently stimulated 121 and 189 kDa isoforms of VEGF, but not the 164kDa isoform. Finally, VEGF expression was observed at both protein and mRNA levels in human growth plate specimens. The protein level increased during pubertal development, supporting a link between estrogens and local VEGF production in the growth plate. We conclude that estrogens regulate VEGF expression in the epiphyseal growth plate, although the precise role of VEGF in estrogen-mediated growth plate fusion remains to be clarified. Journal of Endocrinology (2010) 205, 61-68 Show less
