Objective To investigate the behaviour of common healthcare related objects in a 3 tesla (T) MRI (magnetic resonance imaging) scanner, examining their ability to self-propel towards the scanner bore and their potential for tissue penetration. Design Prospective in situ experimental study. Setting Clinical 3 T MRI scanner. Customised rig designed and built to guide objects towards the scanner bore. Participants 12 categories of objects commonly found in hospitals, or on patients or healthcare professionals, or near an MRI scanning room. Human tissue penetration simulated with ballistic gel (Federal Bureau of Investigation and North Atlantic Treaty Organisation graded). Main outcome measures SANTA (site where applied newtonian mechanics triggers acceleration) measurements and depth of tissue penetration of the objects. Results SANTA measurements ranged from 0 cm for the 20 pence, 50 pence, and £2 coins to 152-161 cm for a knife and the biscuit tins. One penny, two pence, five pence, and 10 pence coins showed self-propulsion and acceleration towards the scanner bore at a distance >100 cm from the gantry entry point. Linear regression analysis showed no apparent correlation between the weight of the objects and their SANTA measurements (R2<0.1). Only five objects penetrated the ballistic gel (simulated human tissue). The deepest penetration was by the knife (5.5 cm), closely followed by the teaspoon (5.0 cm), fork (4.0 cm), spoon (3.5 cm), and a 10 pence coin (0.5 cm). Although the biscuit tins did not penetrate the simulated human tissue, they exerted substantial impact force which could potentially cause bone fractures. A smartphone, digital thermometer, metallic credit card, and pen torch remained fully functional after several passes into the MRI scanner. No discernible loss of image quality for the MRI scanner after the experiments was found. Conclusions The study highlights the potential for harm (major tissue damage and bone fractures) when commonly found objects in a healthcare setting are unintentionally brought into the MRI scanner room. Patients and healthcare professionals need to be aware of the dangers associated with bringing ferromagnetic objects into the MRI environment. Additional data are available on reasonable request from the corresponding author.

中文翻译：

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常见医疗保健相关仪器的磁吸引力研究（CHRISTMAS）：前瞻性原位实验研究

目的 研究常见医疗保健相关物体在 3 特斯拉 (T) MRI（磁共振成像）扫描仪中的行为，检查它们向扫描仪孔自行推进的能力及其组织穿透的潜力。设计前瞻性原位实验研究。设置临床 3 T MRI 扫描仪。定制的装备设计和制造用于引导物体朝向扫描仪孔。参与者 医院、患者或医疗保健专业人员身上或 MRI 扫描室附近常见的 12 类物体。用弹道凝胶模拟人体组织穿透（联邦调查局和北大西洋公约组织分级）。主要结果测量 SANTA（应用牛顿力学触发加速度的位置）测量值和物体组织穿透的深度。结果 SANTA 的测量范围从 20 便士、50 便士和 2 英镑硬币的 0 厘米到刀和饼干罐的 152-161 厘米。1 便士、2 便士、5 便士和 10 便士硬币在距离龙门入口点 > 100 厘米处显示出向扫描仪孔的自推进和加速。线性回归分析显示物体的重量与其 SANTA 测量值之间没有明显的相关性 (R2<0.1)。只有五个物体穿透了弹道凝胶（模拟人体组织）。刺入最深的是刀（5.5 厘米），紧随其后的是茶匙（5.0 厘米）、叉子（4.0 厘米）、勺子（3.5 厘米）和 10 便士硬币（0.5 厘米）。尽管饼干罐没有穿透模拟人体组织，但它们产生的巨大冲击力可能会导致骨折。智能手机、数字温度计、金属信用卡和笔式手电筒在多次进入核磁共振扫描仪后仍能正常工作。实验后发现 MRI 扫描仪的图像质量没有明显下降。结论 该研究强调了当医疗机构中常见的物体被无意带入 MRI 扫描仪室时，可能会造成伤害（主要组织损伤和骨折）。患者和医疗保健专业人员需要意识到将铁磁物体带入 MRI 环境所带来的危险。可根据相应作者的合理要求提供更多数据。