Gianesin Barbara, Zefiro Daniele, Paparo Francesco, Caminata Alessio, Balocco Manuela, Carrara Paola, Quintino Sabrina, Pinto Valeria, Bacigalupo Lorenzo, Rollandi Gian Andrea, Marinelli Mauro, Forni Gian Luca
Department of Physics, University of Genoa, Italy; S.C. Fisica Sanitaria, E.O. Ospedali Galliera, Genoa, Italy; National Institute of Nuclear Physics, Genoa, Italy.
Magn Reson Med. 2015 May;73(5):2030-7. doi: 10.1002/mrm.25604. Epub 2015 Mar 26.
A preliminary assessment of the MRI-compatibility of metallic object possibly embedded within the patient is required before conducting the MRI examination. The Magnetic Iron Detector (MID) is a highly sensitive susceptometer that uses a weak magnetic field to measure iron overload in the liver. MID might be used to perform a screening procedure for MRI by determining the ferromagnetic/conductive properties of embedded metallic objects.
The study was composed by: (i) definition of MID sensitivity threshold; (ii) application of MID in a procedure to characterize the ferromagnetic/conductive properties of metallic foreign objects in 958 patients scheduled for MID examination.
The detection threshold for ferromagnetic objects was found to be the equivalent of a piece of wire of length 2 mm and gauge 0.8 mm(2) and, representing purely conductive objects, an aluminum sheet of area 2 × 2 cm(2) . Of 958 patients, 165 had foreign bodies of unknown nature. MID was able to detect those with ferromagnetic and/or conducting properties based on fluctuations in the magnetic and eddy current signals versus control.
The high sensitivity of MID makes it suitable for assessing the ferromagnetic/conductive properties of metallic foreign objects embedded within the body of patients scheduled for MRI.
在进行MRI检查之前，需要对患者体内可能存在的金属物体的MRI兼容性进行初步评估。磁性铁探测器（MID）是一种高灵敏度的磁化率计，它利用弱磁场来测量肝脏中的铁过载情况。MID可通过确定体内嵌入金属物体的铁磁/导电特性，用于对MRI进行筛查。
该研究包括：（i）确定MID的灵敏度阈值；（ii）将MID应用于对958例计划进行MID检查的患者体内金属异物的铁磁/导电特性进行表征的过程中。
发现铁磁物体的检测阈值相当于一根长度为2毫米、规格为0.8毫米（2）的金属丝，对于纯导电物体，检测阈值相当于一块面积为2×2平方厘米的铝板。在958例患者中，有165例体内有性质不明的异物。MID能够根据与对照相比的磁信号和涡流信号波动，检测出具有铁磁和/或导电特性的异物。
MID的高灵敏度使其适用于评估计划进行MRI检查的患者体内嵌入金属异物的铁磁/导电特性。
