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A special phase detector for magnetic inductive measurement of cerebral hemorrhage.

Jin G, Sun J, Qin M - PLoS ONE (2014)

Bottom Line: The noise and drift decreased as the frequency decreased.The results are in agreement with those from previous reports.The results from the injection group showed a similar trend of increasing phase shift change with increasing injection volume.

View Article: PubMed Central - PubMed

Affiliation: College of Biomedical Engineering, Third Military Medical University, Chongqing, China.

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.

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Phase shift caused by injecting and pumping 80 ml of solution.
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pone-0097179-g007: Phase shift caused by injecting and pumping 80 ml of solution.

Mentions: Figure 7 shows the results of the hemorrhage detection. The data were normalized to the initial value. The changes in the MIPS caused by the injection of 80 ml of solution were 0.150°±0.0109°, 0.266°±0.0047° and 0.768°±0.0036° at 1, 10.7 and 21.4 MHz, respectively. Under the same conditions, the MIPS presented an approximately linear decrease as the volume of solution inside the capsule increased, whereas a decrease of the solution volume inside the capsule was accompanied by an approximately linear increase of the MIPS at frequencies of 10.7 and 21.4 MHz; however, the inverse was observed at 1 MHz. This may have occurred because the phase shifts at 10.7 and 21.4 MHz were opposite to those at 1 MHz. Although the best sensitivity was observed at 21.4 MHz, the worst phase drift occurred at 21.4 MHz. Therefore, we chose a frequency of 10.7 MHz for detection in the animal model.


A special phase detector for magnetic inductive measurement of cerebral hemorrhage.

Jin G, Sun J, Qin M - PLoS ONE (2014)

Phase shift caused by injecting and pumping 80 ml of solution.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4016262&req=5

pone-0097179-g007: Phase shift caused by injecting and pumping 80 ml of solution.
Mentions: Figure 7 shows the results of the hemorrhage detection. The data were normalized to the initial value. The changes in the MIPS caused by the injection of 80 ml of solution were 0.150°±0.0109°, 0.266°±0.0047° and 0.768°±0.0036° at 1, 10.7 and 21.4 MHz, respectively. Under the same conditions, the MIPS presented an approximately linear decrease as the volume of solution inside the capsule increased, whereas a decrease of the solution volume inside the capsule was accompanied by an approximately linear increase of the MIPS at frequencies of 10.7 and 21.4 MHz; however, the inverse was observed at 1 MHz. This may have occurred because the phase shifts at 10.7 and 21.4 MHz were opposite to those at 1 MHz. Although the best sensitivity was observed at 21.4 MHz, the worst phase drift occurred at 21.4 MHz. Therefore, we chose a frequency of 10.7 MHz for detection in the animal model.

Bottom Line: The noise and drift decreased as the frequency decreased.The results are in agreement with those from previous reports.The results from the injection group showed a similar trend of increasing phase shift change with increasing injection volume.

View Article: PubMed Central - PubMed

Affiliation: College of Biomedical Engineering, Third Military Medical University, Chongqing, China.

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.

Show MeSH
Related in: MedlinePlus