Nijs H G T, De Groot R, Van Velthoven M F A M, Stoel R D
Netherlands Forensic Institute, Laan van Ypenburg 6, 2497 GB The Hague, The Netherlands.
Netherlands Forensic Institute, Laan van Ypenburg 6, 2497 GB The Hague, The Netherlands.
Forensic Sci Int. 2019 Jan;294:34-38. doi: 10.1016/j.forsciint.2018.10.029. Epub 2018 Nov 5.
To study the visibility of standardized inflicted bruises by using an alternate ('forensic') light source compared to a white light source.
Bruises were inflicted on the flexor site of the forearm (halfway in the middle) in 76 adults, by suddenly allowing a cylindrical metal object (400g) with rounded edges to drop for 1m in a vertically positioned tube. At 0.25, 1, 2, 7 and 14days after this blunt force impact, the impact site on the forearm was photographed with a white light source and subsequently with an alternate light source at 415nm. Visibility of bruises on 170 randomized photographs was assessed on a calibrated monitor by 10 forensic medical specialists (physicians and pathologists) independently in two sessions: (1) with white light source photographs, and (2) after a mean of 11days with greyscale converted alternate light source photographs. Bruise visibility was expressed as a report mark between 1 (very bad) and 10 (excellent), or as 'no visible bruise'. To determine intra-rater agreement, 10 of 170 photographs were assessed twice (untold to the assessors). In total 3600 (180×10×2) photographs were assessed.
39 of 73 (53%) participants who completed the study, developed a visible bruise (women more often than men, p<0.001). Inter-rater agreement between assessors was high (mean inter-class coefficient, ICC, for white light source 0.66 (SD 0.14) and for alternate light source ICC 0.73 (0.09)). Intra-rater agreement was excellent (mean ICC 0.88 (SD 0.09)). Mean report marks for bruise visibility, recorded independently by 10 assessors on 170 unique photographs per light source, were significantly higher with an alternate light source than with a white light source, at 1 and 2days after impact: 4.4 (SD 2.0) vs 3.8 (1.8) (p<0.01) and 4.9 (2.1) vs 4.5 (2.0) (p<0.05), respectively. However, these differences were small, as the mean difference (effect size) in report marks were 0.6 (0.5) and 0.4 (0.3), at 1 and 2days after impact, respectively. The other time points showed no statistical significant differences in report marks.
Bruises after standardized blunt force impact were slightly better visible with an alternate light source than with a white light source after 1 and 2 days, but not after 0.25, 7 and 14 days. The value of using an alternate light source at 415nm to improve bruise visibility was limited in this study.
与白色光源相比，研究使用替代（“法医”）光源时标准人为造成瘀伤的可见性。
在76名成年人的前臂屈侧（中间位置）造成瘀伤，方法是让一个边缘圆润的圆柱形金属物体（400克）在垂直放置的管中从1米高处突然落下。在这种钝力撞击后的0.25、1、2、7和14天，先用白色光源拍摄前臂的撞击部位，随后用415纳米的替代光源拍摄。10名法医专家（医生和病理学家）分两个阶段独立在校准显示器上评估170张随机照片上瘀伤的可见性：（1）使用白色光源照片时；（2）平均11天后使用灰度转换后的替代光源照片时。瘀伤可见性用1（非常差）到10（优秀）之间的报告分数表示，或者表示为“无可见瘀伤”。为确定评估者内部的一致性，对170张照片中的10张进行了两次评估（评估者不知情）。总共评估了3600张（180×10×2）照片。
完成研究的73名参与者中有39名（53%）出现了可见瘀伤（女性比男性更常见，p<0.001）。评估者之间的评估者间一致性较高（白色光源的平均组内相关系数，ICC，为0.66（标准差0.14），替代光源的ICC为0.73（0.09））。评估者内部一致性极佳（平均ICC为0.88（标准差0.09））。10名评估者在每种光源的170张独特照片上独立记录的瘀伤可见性平均报告分数，在撞击后1天和2天，替代光源显著高于白色光源：分别为4.4（标准差2.0）对3.8（1.8）（p<0.01）和4.9（2.1）对4.5（2.0）（p<0.05）。然而，这些差异很小，因为撞击后1天和2天报告分数的平均差异（效应大小）分别为0.6（0.5）和0.4（0.3）。其他时间点的报告分数没有统计学上的显著差异。
标准钝力撞击后的瘀伤在1天和2天后使用替代光源比白色光源稍易见，但在0.25、7和14天后并非如此。在本研究中，使用415纳米的替代光源来提高瘀伤可见性的价值有限。
