title: A special phase detector for magnetic inductive measurement of cerebral hemorrhage.
abstract: Cerebral hemorrhage is an important clinical problem that is often monitored and studied with expensive techniques, such as computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET). These devices are not readily available in economically underdeveloped regions of the world and in emergency departments and emergency zones. The magnetic inductive method is an emerging technology that may become a new tool to detect cerebral hemorrhage. In this study, a special phase detector (PD) was developed and used for cerebral hemorrhage detection with the magnetic inductive method. The performance indicated that the PD can achieve phase noise as low as 6 m° and a 4-hour phase drift as low as 30 m° at 21.4 MHz. The noise and drift decreased as the frequency decreased. The performance at 10.7 MHz was slightly better than that of other recently developed phase detection systems. To test the practicality of the system, the PD was used to detect the volume change in a self-made physical model of the brain. The measured phase shift was approximately proportional to the volume change of physiological saline inside the model. The change of the phase shift increased as the volume change and frequency increased. The results are in agreement with those from previous reports. To verify the feasibility of in vivo detection, an autologous blood injection model was established in rabbit brain. The results from the injection group showed a similar trend of increasing phase shift change with increasing injection volume. The average phase shift change induced by a 3-ml injection of blood was 0.502°±0.119°, which was much larger than that of the control group. The measurement system can distinguish a minimal cerebral hemorrhage volume of approximately 0.5 ml. All of the results demonstrated that the PD used with this method can detect cerebral hemorrhage.
authors.affiliation: College of Biomedical Engineering, Third Military Medical University, Chongqing, China.
authors.forename: Gui
authors.initials: G
authors.lastname: Jin
authors.affiliation: College of Biomedical Engineering, Third Military Medical University, Chongqing, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
authors.affiliation: College of Biomedical Engineering, Third Military Medical University, Chongqing, China.
authors.forename: Mingxin
authors.initials: M
authors.lastname: Qin
authors.affiliation: College of Electronic Engineering, Xidian University, Xi'an, China.
authors.lastname: Chao Wang
authors.affiliation: College of Electronic Engineering, Xidian University, Xi'an, China.
authors.forename: Wanyou
authors.initials: W
authors.lastname: Guo
authors.affiliation: College of Biomedical Engineering, Third Military Medical University, Chongqing, China.
authors.forename: Qingguang
authors.initials: Q
authors.lastname: Yan
authors.affiliation: College of Biomedical Engineering, Third Military Medical University, Chongqing, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Peng
authors.affiliation: College of Biomedical Engineering, Third Military Medical University, Chongqing, China.
authors.forename: Wencai
authors.initials: W
authors.lastname: Pan
mesh_terms: D000818:Animals; D002543:Cerebral Hemorrhage / Q000175:diagnosis*; D008280:Magnetics / Q000295:instrumentation* / Q000379:methods; D008954:Models, Biological; D011817:Rabbits