Longitudinal [18F]FDG and [13N]NH3 PET/CT imaging of brain and spinal cord in a canine hemisection spinal cord injury model

Toward Functional PET Imaging of the Spinal Cord

At present, spinal cord imaging primarily uses magnetic resonance imaging (MRI) or computed tomography (CT), but the greater sensitivity of positron emission tomography (PET) techniques and the development of new radiotracers are paving the way for a new approach. The substantial rise in publications on PET radiotracers for spinal cord exploration indicates a growing interest in the functional and molecular imaging of this organ. The present review aimed to provide an overview of the various radiotracers used in this indication, in preclinical and clinical settings. Firstly, we outline spinal cord anatomy and associated target pathologies. Secondly, we present the state-of-the-art of spinal cord imaging techniques used in clinical practice, with their respective strengths and limitations. Thirdly, we summarize the literature on radiotracers employed in functional PET imaging of the spinal cord. In conclusion, we propose criteria for an ideal radiotracer for molecular spinal cord imaging, emphasizing the relevance of multimodal hybrid cameras, and particularly the benefits of PET-MRI integration.

Development of an innovative minimally invasive primate spinal cord injury model: A case report

Spinal cord injury (SCI) animal models have been widely created and utilized for repair therapy research, but more suitable experimental animals and accurate modeling methodologies are required to achieve the desired results. In this experiment, we constructed an innovative dorsal 1/4 spinal cord transection macaque model that had fewer severe problems, facilitating postoperative care and recovery. In essence, given that monkeys and humans share similar genetics and physiology, the efficacy of this strategy in a nonhuman primate SCI model basically serves as a good basis for its prospective therapeutic use in human SCI.

Utilizing Additive Manufacturing to Produce Organ Mimics and Imaging Phantoms

The complex geometries and material properties necessary for generating accurate organ mimics require new procedures and methods to fully utilize current technologies. The increased accessibility of 3D printers, along with more specialized bioprinters, allow the creation of highly tunable models of various body parts. Three-dimensional printing can reduce lead-time on custom parts, produce structures based on imaging data in patients, and generate a test bench for novel surgical methods. This technical note will cover three unique case studes and offer insights for how 3D printing can be used for lab research. Each case follows a unique design process in comparison to traditional manufacturing workflows as they required significantly more iterative design. The strengths of different printing technologies, design choices, and structural/chemical requirements all influence the design process. Utilization of in-house manufacturing allows for greater flexibility and lower lead-times for novel research applications. Detailed discussions of these design processes will help reduce some of the major barriers to entry for these technologies and provide options for researchers working in the field.

A case of Kernohan-Woltman notch phenomenon caused by an epidural hematoma: the diagnostic and prognostic value of PET/CT imaging

Background

Kernohan-Woltman notch phenomenon (KWNP) classically occurs when a lesion causes compression of the contralateral cerebral peduncle against the tentorium, resulting in ipsilateral hemiparesis. It has been studied clinically, radiologically and electrophysiologically which all confirmed to cause false localizing motor signs. Here, we demonstrate the potential use of fluorine-18 fluorodeoxyglucose (18 F-FDG) positron emission tomography/computed tomography (PET/CT) to identify KWNP caused by an epidural hematoma.

Case presentation

A 29-year-old male patient post right-sided traumatic brain injury presenting with persistent ipsilateral hemiparesis. Patient underwent decompressive craniotomy and intracranial hematoma evacuation. Brain magnetic resonance imaging in the postoperative period showed a subtle lesion in the left cerebral peduncle. PET/CT was performed to exclude early brain tumor and explain his ipsilateral hemiparesis. PET/CT imaging demonstrated a focal region of intense 18 F-FDG uptake in the left cerebral peduncle. Throughout the treatment in outpatient neurorehabilitation unit, the patient exhibited a gradual recovery of his right hemiparesis.

Conclusion

In our case report, for the first time, PET/CT offered microstructural and functional confirmation of KWNP. Moreover, our case suggests that 18 F-FDG PET/CT may serve as an important reference for the probability of functional recovery.

Microglial activation in the motor cortex mediated NLRP3-related neuroinflammation and neuronal damage following spinal cord injury

Spinal cord injury (SCI) is a traumatic event that can lead to neurodegeneration. Neuronal damage in the primary motor cortex (M1) can hinder motor function recovery after SCI. However, the exact mechanisms involved in neuronal damage after SCI remain incompletely understood. In this study, we found that microglia were activated in M1 after SCI, which triggered Nod-like receptor protein 3 (NLRP3) related chronic neuroinflammation and neuronal damage in vivo. Meanwhile, treatment with the microglia inhibitor minocycline reduced inflammation-induced neuronal damage in M1, protected the integrity of the motor conduction pathway, and promoted motor function recovery. Furthermore, we simulated chronic inflammation in M1 after SCI by culturing the primary neurons in primary microglia-conditioned medium, and observed that the injury to the primary neurons also occurred in vitro; however, as observed in vivo, these effects could be mitigated by minocycline treatment. Our results indicated that microglial activation in M1 mediates NLRP3-related neuroinflammation and causes the injury to M1 neurons, thereby impairing the integrity of the motor conduction pathway and inhibiting motor function recovery. These findings might contribute to the identification of novel therapeutic strategies for SCI.

SV2A PET Imaging Is a Noninvasive Marker for the Detection of Spinal Damage in Experimental Models of Spinal Cord Injury

Traumatic spinal cord injury (SCI) is a neurologic condition characterized by long-term motor and sensory neurologic deficits as a consequence of an external physical impact damaging the spinal cord. Anatomic MRI is considered the gold-standard diagnostic tool to obtain structural information for the prognosis of acute SCI; however, it lacks functional objective information to assess SCI progression and recovery. In this study, we explored the use of synaptic vesicle glycoprotein 2A (SV2A) PET imaging to detect spinal cord lesions noninvasively after SCI. Methods: Mice (n = 7) and rats (n = 8) subjected to unilateral moderate cervical (C5) contusion were euthanized 1 wk after SCI for histologic and autoradiographic (³H-labeled (4R)-1-[(3-methylpyridin-4-yl)methyl]-4-(3,4,5-trifluorophenyl)pyrrolidin-2-one [UCB-J]) investigation of SV2A levels. Longitudinal ¹¹C-UCB-J PET/CT imaging was performed in sham (n = 7) and SCI rats (n = 8) 1 wk and 6 wk after SCI. Animals also underwent an ¹⁸F-FDG PET scan during the latter time point. Postmortem tissue SV2A analysis to corroborate in vivo PET findings was performed 6 wk after SCI. Results: A significant SV2A loss (ranging from -70.3% to -87.3%; P < 0.0001) was measured at the epicenter of the impact in vitro in both mouse and rat contusion SCI models. Longitudinal ¹¹C-UCB-J PET imaging detected SV2A loss in SCI rats (-49.0% ± 8.1% at 1 wk and -52.0% ± 12.9% at 6 wk after SCI), with no change observed in sham rats. In contrast, ¹⁸F-FDG PET imaging measured only subtle hypometabolism (-17.6% ± 14.7%). Finally, postmortem ³H-UCB-J autoradiography correlated with the in vivo SV2A PET findings (r = 0.92, P < 0.0001). Conclusion:¹¹C-UCB-J PET/CT imaging is a noninvasive marker for SV2A loss after SCI. Collectively, these findings indicate that SV2A PET may provide an objective measure of SCI and thus represent a valuable tool to evaluate novel therapeutics. Clinical assessment of SCI with SV2A PET imaging is highly recommended.

Diagnostic Value of Magnetic Resonance Imaging Scan, Multislice Spiral Computed Tomography Three-Dimensional Reconstruction Combined with Plain Film X-Ray in Spinal Injuries

Objective

The main objective is to explore the diagnostic value of magnetic resonance imaging (MRI) scan, multislice spiral computed tomography (MSCT) three-dimensional reconstruction combined with plain film X-ray in spiral injuries.

Methods

By means of retrospective study, the data of 100 patients with spiral injury treated in our hospital from January 2020 to December 2021 were retrospectively analyzed, and all patients received MRI scan, MSCT three-dimensional reconstruction, and plain film X-ray examination, and by taking the operation results as the reference, the diagnostic results of different diagnostic modalities were analyzed, and the accordance rates (diagnostic result/surgical result × 100%) of the three diagnostic modalities and their combination were calculated, respectively.

Results

Among the 100 patients, 52 cases (52%) had a fracture at the anterior column of the spine, 28 cases (28%) had a fracture at the middle column of the spine, and 20 cases (20%) had a fracture at the posterior column of spine; 24 cases (24%) had simple flexion compression fracture, 60 cases (60%) had burst fracture, 6 cases (6%) had seat belt fracture, and 10 cases (10%) had fracture dislocation. The accordance rate of combined diagnosis for fracture site was 100%, and that for fracture type was 98.0%; MRI could visualize bone marrow injuries, ligamentous injuries, soft tissue injuries, and nerve root injuries that could not be visualized on X-ray plain films, and 3D reconstruction with MSCT could clearly demonstrate the 3D relationship of spinal fracture displacement, fracture line orientation, and spinal injury.

Conclusion

Plain film X-ray is the basic method for diagnosing spinal injuries, while MRI and MSCT have their unique advantages in this regard, and patients with a negative result of X-ray plain film can be examined by MRI and MSCT to observe the spinal injury comprehensively.

Spinal cord injury chronically depresses glucose uptake in the rodent model

The pathophysiology following spinal cord injury (SCI) progresses from its lesion epicenter resulting in cellular and systemic changes acutely, sub-acutely and chronically. The symptoms of the SCI depend upon the severity of the injury and its location in the spinal cord. However, there is lack of studies that have longitudinally assessed acute through chronic in vivo changes following SCI. In this combinatorial study we fill this gap by evaluating acute to chronic effects of moderate SCI in rats. We have used fluorodeoxyglucose (FDG) imaging with positron emission tomography (PET) as a marker to assess glucose metabolism, motor function, and immunohistochemistry to examine changes following moderate SCI. Our results demonstrate decreased FDG uptake at the injury site chronically at days 28 and 90 post injury compared to baseline. This alteration in glucose uptake was not restricted to the lesion site, showing depressed FDG uptake in non-injured areas (cervical spinal cord and cerebellum). The alteration in glucose uptake was correlated with reductions in neuronal cell viability and increases in glial cell activation at 90 days at the lesion site, as well as chronic impairments in motor function. These data demonstrate the chronic effects of SCI on glucose metabolism both within the lesion and distally within the spinal cord and brain.

Connectomic mapping of brain-spinal cord neural networks: future directions in assessing spinal cord injury at rest

Following spinal cord injury (SCI), the central nervous system undergoes significant reconstruction. The dynamic change in the interaction of the brain-spinal cord axis as well as in structure-function relations plays a vital role in the determination of neurological functions, which might have important clinical implications for the treatment and its efficacy evaluation of patients with SCI. Brain connectomes based on neuroimaging data is a relatively new field of research that maps the brain's large-scale structural and functional networks at rest. Importantly, increasing evidence shows that such resting-state signals can also be seen in the spinal cord. In the present review, we focus on the reconstruction of multi-level neural circuits after SCI. We also describe how the connectome concept could further our understanding of neuroplasticity after SCI. We propose that mapping the cortical-subcortical-spinal cord networks can provide novel insights into the pathologies of SCI.