Assessment of Therapeutic Response in Pyogenic Vertebral Osteomyelitis Using 18F-FDG-PET/MRI.

PURPOSE: There is still no definite method to determine therapeutic response in pyogenic vertebral osteomyelitis (PVO). We analyzed the value of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) for assessing therapeutic response in PVO. METHODS: This retrospective study included 53 patients (32 men and 21 women) with lumbar PVO. The results of clinical assessments for therapeutic response were divided into "Cured" (group C) and "Non-cured" (group NC). The differences in clinical and radiological features of PVO lesions between the two groups were analyzed using clinical data and simultaneous FDG-PET/magnetic resonance imaging (MRI) obtained at each clinical assessment. RESULTS: Clinical assessments and FDG-PET/MRIs were performed at 41.89 ± 16.08 (21-91) days of parenteral antibiotic therapy. There were 39 patients in group C and 14 in group NC. Diagnostic accuracies (DAs) of FDG uptake intensity-based interpretation and C-reactive protein (CRP) for residual PVO were as follows (p < 0.01): 84.9% of the maximum standardized uptake value of PVO lesion (PvoSUVmax), 86.8% of ΔPvoSUVmax-NmlSUVmax (SUVmax of normal vertebra), 86.8% of ΔPvoSUVmax-NmlSUVmean (SUVmean of normal vertebra), and 71.7% of CRP. DAs were better (92.5-94.3%) when applying FDG uptake intensity-based interpretation and CRP together. Under the FDG uptake distribution-based interpretation, FDG uptake was significantly limited to intervertebral structures in group C (p = 0.026). CONCLUSION: The interpretations of intensity and distribution of FDG uptake on FDG-PET are useful for detecting residual PVO in the assessment of therapeutic response of PVO. The combination of FDG-PET and CRP is expected to increase DA for detecting residual PVO.

Clinical and Radiological Analysis of Pyogenic Vertebral Osteomyelitis Immediately after Successful Antimicrobial Therapy: Considerations for Assessing Therapeutic Response.

PURPOSE: The clinical and radiological abnormal findings continue even after successful treatment in pyogenic vertebral osteomyelitis (PVO). We analyzed the clinical and radiological features of cured PVO based on 18F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (FDG-PET/MRI) and compared the radiological differences between FDG-PET and MRI for assessing therapeutic response in PVO. METHODS: This study included 43 patients (28 men and 15 women) with lumbar PVO who had no recurrence after successful antimicrobial therapy. They were divided into two groups based on the location of maximum standardized FDG uptake value (SUVmax) of PVO lesion on FDG-PET/MRI when parenteral antibiotics were discontinued (31 in group A: Intervertebral structure; 12 in group B: Vertebral body and paravertebral muscle). The differences of clinical symptoms, hematological inflammatory indices, and radiological features were retrospectively analyzed. RESULTS: The patients were treated with 42.28 ± 14.58 (21-89) days of parenteral antibiotics. There were significant differences in C-reactive protein (0.97 ± 1.10 vs. 0.51 ± 0.31 mg/dL, p = 0.041; normal range of CRP < 0.5), back pain (4.29 ± 1.13 vs. 3.50 ± 1.00, p = 0.040; visual analog scale), and SUVmax (4.34 ± 1.24 vs. 5.89 ± 1.57, p < 0.001) between the two groups. In the distribution pattern of PVO lesions, FDG-PET overall showed recovery pattern earlier than MRI did (p < 0.001). CONCLUSIONS: In cured PVO, the clinical features vary depending on the location of major structural damage of PVO lesion. The involvement of intervertebral structure is related with sustained back pain and elevation of CRP, and vertebral body/paravertebral muscle shows favorable clinical features despite advanced structural damages.

Quantitative volumetric analysis of the optic radiation in the normal human brain using diffusion tensor magnetic resonance imaging-based tractography.

To attain the volumetric information of the optic radiation in normal human brains, we performed diffusion tensor imaging examination in 13 healthy volunteers. Simultaneously, we used a brain normalization method to reduce individual brain variation and increase the accuracy of volumetric information analysis. In addition, tractography-based group mapping method was also used to investigate the probability and distribution of the optic radiation pathways. Our results showed that the measured optic radiation fiber tract volume was a range of about 0.16% and that the fractional anisotropy value was about 0.53. Moreover, the optic radiation probability fiber pathway that was determined with diffusion tensor tractography-based group mapping was able to detect the location relatively accurately. We believe that our methods and results are helpful in the study of optic radiation fiber tract information.

Curvature range measurements of the arcuate fasciculus using diffusion tensor tractography.

Because Broca's area and Wernicke's area in the brain are connected by the arcuate fasciculus, understanding the anatomical location and morphometry of the arcuate fasciculus can help in the treatment of patients with aphasia. We measured the horizontal and vertical curvature ranges of the arcuate fasciculus in both hemispheres in 12 healthy subjects using diffusion tensor tractography. In the right hemisphere, the direct curvature range and indirect curvature range values of the arcuate fasciculus horizontal part were 121.13 ± 5.89 and 25.99 ± 3.01 degrees, respectively, and in the left hemisphere, the values were 121.83 ± 5.33 and 27.40 ± 2.96 degrees, respectively. In the right hemisphere, the direct curvature range and indirect curvature range values of the arcuate fasciculus vertical part were 43.97 ± 7.98 and 30.15 ± 3.82 degrees, respectively, and in the left hemisphere, the values were 39.39 ± 4.42 and 24.08 ± 4.34 degrees, respectively. We believe that the measured curvature ranges are important data for localization and quantitative assessment of specific neuronal pathways in patients presenting with arcuate fasciculus abnormalities.

Neuronal loss in the medial cholinergic pathway from the nucleus basalis of Meynert in patients with traumatic axonal injury: a preliminary diffusion tensor imaging study.

OBJECTIVE: The recent development of diffusion tensor imaging (DTI) allows visualization and estimation of the medial cholinergic pathway (MCP), which originates from the nucleus basalis of Meynert and provides cortical cholinergic innervation to the cerebral cortex. We investigated the injury to the MCP in patients with traumatic axonal injury (TAI), using DTI. DESIGN: Retrospective survey. PARTICIPANTS: Fourteen patients with chronic TAI and 14 age- and sex-matched normal control subjects. MAIN OUTCOME MEASURES: Using the Functional Magnetic Resonance Imaging of the Brain (FMRIB) Software Library (FMRIB analysis group, Oxford University, United Kingdom), diffusion tensor images were acquired by using a sensitivity-encoding head coil at 1.5 T DTIs. Fractional anisotropy (FA), mean diffusivity (MD), and tract volume of the MCP were measured. RESULTS: The FA value and tract volume were significantly decreased in the group with TAI compared with those of the control group (P < .05); in contrast, there was no difference in the MD value between the 2 groups (P > .05). CONCLUSIONS: Changes in DTI parameters of the TAI group appear to be due to neuronal loss of the MCP. We believe that DTI would be useful for the evaluation of the MCP in patients with TAI.

Identification of the anterior corticospinal tract in the human brain using diffusion tensor imaging.

The corticospinal tract (CST) is generally classified into the crossed lateral CST and the uncrossed anterior CST. No diffusion tensor imaging study for identification of the anterior CST in the human brain has been conducted. Using diffusion tensor imaging, we attempted to identify the anterior CST and investigate the characteristics of the anterior CST in the normal human brain. We recruited 15 healthy volunteers for this study. Diffusion tensor images were scanned using 1.5T. For the whole CST, two regions of interest were placed on the CST area of the pons and upper medulla. By contrast, for the anterior CST, an additional region of interest was given on the anterior funiculus of the upper cervical cord. The anterior CSTs, which originated from the cerebral cortex descended through the known pathway of the CST, and terminated in the anterior funiculus of the upper cervical cord. Compared with whole CSTs, the anterior CSTs showed decreased fiber number, fractional anisotropy, and apparent diffusion coefficient (P<0.05). The mean fiber number of the anterior CST was 12.4% of the whole CSTs. We identified the anterior CST and found that it has the characteristics of less directionality and fewer fibers in comparison with the whole CST. We believe that the methodology and results of this study would be helpful in research on motor control in the normal human brain and motor recovery mechanisms following brain injury.

The rubrospinal tract in the human brain: diffusion tensor imaging study.

The rubrospinal tract (RST) is an extrapyramidal motor pathway in the human brain. In this study, using diffusion tensor tractography (DTT), we attempted to identify the RST in the normal human brain. Twenty-one healthy volunteers were recruited for this study. A 1.5-T scanner was used for scanning of diffusion tensor images, and the RSTs were isolated by DTT using FMRIB software. Values of fractional anisotropy (FA), mean diffusivity (MD), and tract volume of the RSTs were measured. Among 42 hemispheres of 21 subjects, RSTs were isolated in 27 hemispheres (64.28%) of 15 subjects. All identified tracts originated from the red nucleus and crossed the midline via ventral tegmental decussation. Then, they passed through the area between the inferior olivary nucleus and the inferior cerebellar peduncle in the contralateral medulla. The tracts finally descended through the lateral funiculus of the upper spinal cord. Mean values of FA, MD, and tract volume did not differ significantly between the left and right hemispheres (P>0.05). We believe that the methodologies used and the results of this study would be helpful to researchers interested in the function of the human RST and its clinical implications.

Dentatorubrothalamic tract in human brain: diffusion tensor tractography study.

INTRODUCTION: The dentatorubrothalamic tract (DRTT) originates from the dentate nucleus in the cerebellum and terminates in the contralateral ventrolateral nucleus (VL) of the thalamus after decussating to the contralateral red nucleus. Identification of the DRTT is difficult due to the fact that it is a long, multisynaptic, neural tract crossing to the opposite hemisphere. In the current study, we attempted to identify the DRTT in the human brain using a probabilistic tractography technique of diffusion tensor imaging. METHODS: Diffusion tensor imaging was performed at 1.5-T using a synergy-L sensitivity encoding head coil. DRTTs were obtained by selection of fibers passing through three regions of interest (the dentate nucleus, the superior cerebellar peduncle, and the contralateral red nucleus) from 41 healthy volunteers. Probabilistic mapping was obtained from the highest probabilistic location at 2.3 mm above the anterior commissure-posterior commissure level. RESULTS: DRTTs of all subjects, which originated from the dentate nucleus, ascended through the junction of the superior cerebellar peduncle and the contralateral red nucleus and then terminated at the VL nucleus of the thalamus. The highest probabilistic location for the DRTT at the thalamus was compatible with the location of the VL nucleus. CONCLUSIONS: We identified the DRTT in the human brain using probabilistic tractography. Our results could be useful in research on movement control.

Dual-modal nanoprobes for imaging of mesenchymal stem cell transplant by MRI and fluorescence imaging.

OBJECTIVE: To determine the feasibility of labeling human mesenchymal stem cells (hMSCs) with bifunctional nanoparticles and assessing their potential as imaging probes in the monitoring of hMSC transplantation. MATERIALS AND METHODS: The T1 and T2 relaxivities of the nanoparticles (MNP@SiO(2)[RITC]-PEG) were measured at 1.5T and 3T magnetic resonance scanner. Using hMSCs and the nanoparticles, labeling efficiency, toxicity, and proliferation were assessed. Confocal laser scanning microscopy and transmission electron microscopy were used to specify the intracellular localization of the endocytosed iron nanoparticles. We also observed in vitro and in vivo visualization of the labeled hMSCs with a 3T MR scanner and optical imaging. RESULTS: MNP@SiO(2)(RITC)-PEG showed both superparamagnetic and fluorescent properties. The r(1) and r(2) relaxivity values of the MNP@SiO(2)(RITC)-PEG were 0.33 and 398 mM(-1) s(-1) at 1.5T, respectively, and 0.29 and 453 mM(-1) s(-1) at 3T, respectively. The effective internalization of MNP@SiO(2)(RITC)-PEG into hMSCs was observed by confocal laser scanning fluorescence microscopy. The transmission electron microscopy images showed that MNP@SiO(2)(RITC)-PEG was internalized into the cells and mainly resided in the cytoplasm. The viability and proliferation of MNP@SiO(2)(RITC)-PEG-labeled hMSCs were not significantly different from the control cells. MNP@SiO(2)(RITC)-PEG-labeled hMSCs were observed in vitro and in vivo with optical and MR imaging. CONCLUSION: MNP@SiO(2)(RITC)-PEG can be a useful contrast agent for stem cell imaging, which is suitable for a bimodal detection by MRI and optical imaging.