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MRI detection of bacterial brain abscesses and monitoring of antibiotic treatment using bacCEST.

ABSTRACT: PURPOSE:To develop a new MRI method to detect and characterize brain abscesses using the CEST contrast inherently carried by bacterial cells, namely bacCEST. METHODS:Bacteria S. aureus (ATCC #49775) and F98 and 9L glioma cells were injected stereotactically in the brains of F344 rats to form abscesses and tumors. The CEST signals of brain abscesses (n?=?4) and tumors (n?=?7) were acquired using 2 B1 values (i.e., 1 and 3?µT) and compared. The bacCEST signal of the brain abscesses in the rats (n?=?3) receiving ampicillin (intraperitoneal injection 40?mg/kg twice daily) was acquired before, 4 and 10 days after the treatment. RESULTS:The bacCEST signal of S. aureus was characterized in vitro as a strong and broad signal in the range of 1 to 4?ppm, with the maximum contrast occurring at 2.6?ppm. The CEST signal in S. aureus-induced brain abscesses was significantly higher than that of contralateral parenchyma (p?=?.003). Moreover, thanks to their different B1 independence, brain abscesses and tumors could be effectively differentiated (p?=?.005) using ?CEST(2.6?ppm, 3?µT-1?µT), defined by the difference between the CEST signal (offset?=?2.6?ppm) acquired using B1 ?=?3?µT and that of 1?µT. In treated rats, bacCEST MRI could detect the response of bacteria as early as 4 days after the antibiotic treatment (p?=?.035). CONCLUSION:BacCEST MRI provides a new imaging method to detect, discriminate, and monitor bacterial infection in deep-seated organs. Because no contrast agent is needed, such an approach has a great translational potential for detecting and monitoring bacterial infection in deep-seated organs.

SUBMITTER: Liu J

PROVIDER: S-EPMC5910221 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature

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MRI detection of bacterial brain abscesses and monitoring of antibiotic treatment using bacCEST.

Liu Jing J Bai Renyuan R Li Yuguo Y Staedtke Verena V Zhang Shuixing S van Zijl Peter C M PCM Liu Guanshu G

Magnetic resonance in medicine 20180325 2

<h4>Purpose</h4>To develop a new MRI method to detect and characterize brain abscesses using the CEST contrast inherently carried by bacterial cells, namely bacCEST.<h4>Methods</h4>Bacteria S. aureus (ATCC #49775) and F98 and 9L glioma cells were injected stereotactically in the brains of F344 rats to form abscesses and tumors. The CEST signals of brain abscesses (n = 4) and tumors (n = 7) were acquired using 2 B<sub>1</sub> values (i.e., 1 and 3 µT) and compared. The bacCEST signal of the brain ...[more]

PMID: 29577382

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Project description:IntroductionBrain multimodal monitoring including intracranial pressure (ICP) and brain tissue oxygen pressure (PbtO2) is more accurate than ICP alone in detecting cerebral hypoperfusion after traumatic brain injury (TBI). No data are available for the predictive role of a dynamic hyperoxia test in brain-injured patients from diverse etiology.AimTo examine the accuracy of ICP, PbtO2 and the oxygen ratio (OxR) in detecting regional cerebral hypoperfusion, assessed using perfusion cerebral computed tomography (CTP) in patients with acute brain injury.MethodsSingle-center study including patients with TBI, subarachnoid hemorrhage (SAH) and intracranial hemorrhage (ICH) undergoing cerebral blood flow (CBF) measurements using CTP, concomitantly to ICP and PbtO2 monitoring. Before CTP, FiO2 was increased directly from baseline to 100% for a period of 20 min under stable conditions to test the PbtO2 catheter, as a standard of care. Cerebral monitoring data were recorded and samples were taken, allowing the measurement of arterial oxygen pressure (PaO2) and PbtO2 at FiO2 100% as well as calculation of OxR (= ΔPbtO2/ΔPaO2). Regional CBF (rCBF) was measured using CTP in the tissue area around intracranial monitoring by an independent radiologist, who was blind to the PbtO2 values. The accuracy of different monitoring tools to predict cerebral hypoperfusion (i.e., CBF < 35 mL/100 g × min) was assessed using area under the receiver-operating characteristic curves (AUCs).ResultsEighty-seven CTPs were performed in 53 patients (median age 52 [41-63] years-TBI, n = 17; SAH, n = 29; ICH, n = 7). Cerebral hypoperfusion was observed in 56 (64%) CTPs: ICP, PbtO2 and OxR were significantly different between CTP with and without hypoperfusion. Also, rCBF was correlated with ICP (r = - 0.27; p = 0.01), PbtO2 (r = 0.36; p < 0.01) and OxR (r = 0.57; p < 0.01). Compared with ICP alone (AUC = 0.65 [95% CI, 0.53-0.76]), monitoring ICP + PbO2 (AUC = 0.78 [0.68-0.87]) or ICP + PbtO2 + OxR (AUC = 0.80 (0.70-0.91) was significantly more accurate in predicting cerebral hypoperfusion. The accuracy was not significantly different among different etiologies of brain injury.ConclusionsThe combination of ICP and PbtO2 monitoring provides a better detection of cerebral hypoperfusion than ICP alone in patients with acute brain injury. The use of dynamic hyperoxia test could not significantly increase the diagnostic accuracy.

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Dataset Information

MRI detection of bacterial brain abscesses and monitoring of antibiotic treatment using bacCEST.

Publications

MRI detection of bacterial brain abscesses and monitoring of antibiotic treatment using bacCEST.

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