Consecutive assessment of recovery after peripheral nerve injury of the sciatic nerve within the same rat using PET/MRI.

BACKGROUND: Positron emission tomography (PET) has been reported as effective in diagnosing peripheral nerve injury (PNI). However, there is a lack of studies evaluating different degrees of PNI using PET within the same individual to reduce errors due to interindividual differences. PURPOSE: To evaluate the recovery process in the same rat after sciatic nerve injury using PET/magnetic resonance imaging (MRI). MATERIAL AND METHODS: Crushing nerve injuries were induced in the left sciatic nerves of six male rats, preserving the right ones. The degree of nerve damage was measured at one, two, three, four, and five weeks postoperatively using three assessment methods: paw withdrawal threshold test (RevWT); PET (SUVR); and MRI (MRSIR). All the representing values of each method are presented as ratio values of the right and left sides in each rat. RESULTS: Significant gradual recovery of all rats was observed over time in all the methods. No significant differences in RevWT and MRSIR were observed between before and more than four weeks after injury, whereas a significant difference in SUVR was still observed between before and five weeks after injury (P = 0.0007). The parameters of all methods decreased significantly over time (P = 0.000, all), and the explanatory power was significant in RevWT, SUVR, and MRSIR. CONCLUSION: PET and MRI could be valuable non-invasive techniques for diagnosing neuropathic pain resulting from PNI. PET/MRI would be expected to be a more accurate and informative diagnostic tool for PNI than MRI alone.

Evaluation of peripheral nerve injury according to the severity of damage using 18F-FDG PET/MRI in a rat Model of sciatic nerve injury.

OBJECTIVES: We ascertained that the PET scan may be a valuable imaging modality for the noninvasive, objective diagnosis of neuropathic pain caused by peripheral nerve injury through the previous study. This study aimed to assess peripheral nerve damage according to severity using18F-FDG PET/MRI of the rat sciatic nerve. METHODS: Eighteen rats were divided into three groups: 30-second (G1), 2-minute (G2), and 5-minute (G3) crushing injuries. The severity of nerve damage was measured in the third week after the crushing injury using three methods: the paw withdrawal threshold test (RevWT), standardized uptake values on PET (SUVR), and intensity analysis on immunohistochemistry (IntR). RESULTS: There were significant differences between G1 and G3 in both SUVR and IntR (p = 0.012 and 0.029, respectively), and no significant differences in RevWT among the three groups (p = 0.438). There was a significant difference in SUVR (p = 0.012), but no significant difference in IntR between G1 and G2 (p = 0.202). There was no significant difference between G2 and G3 in SUVR and IntR (p = 0.810 and 0.544, respectively). DISCUSSION: Although PET did not show results consistent with those of immunohistochemistry in all respects, this study demonstrated that PET uptake tended to increase with severe nerve damage. If this research is supplemented by further experiments, PET/MRI can be used as an effective diagnostic modality.

Evaluation of the Photoplethysmogram-Based Deep Learning Model for Continuous Respiratory Rate Estimation in Surgical Intensive Care Unit.

The respiratory rate (RR) is a significant indicator to evaluate a patient's prognosis and status; however, it requires specific instrumentation or estimates from other monitored signals. A photoplethysmogram (PPG) is extensively used in clinical environments as well as in intensive care units (ICUs) to primarily monitor peripheral circulation while capturing indirect information about intrathoracic pressure changes. This study aims to apply and evaluate several deep learning models using a PPG for the continuous and accurate estimation of the RRs of patients. The dataset was collected twice for 2 min each in 100 patients aged 18 years and older from the surgical intensive care unit of a tertiary referral hospital. The BIDMC and CapnoBase public datasets were also analyzed. The collected dataset was preprocessed and split according to the 5-fold cross-validation. We used seven deep learning models, including our own Dilated Residual Neural Network, to check how accurately the RR estimates match the ground truth using the mean absolute error (MAE). As a result, when validated using the collected dataset, our model showed the best results with a 1.2628 ± 0.2697 MAE on BIDMC and RespNet and with a 3.1268 ± 0.6363 MAE on our dataset, respectively. In conclusion, RR estimation using PPG-derived models is still challenging and has many limitations. However, if there is an equal amount of data from various breathing groups to train, we expect that various models, including our Dilated ResNet model, which showed good results, can achieve better results than the current ones.

Sinus Floor Augmentation Using Recombinant Human Bone Morphogenetic Protein-2 With Hydroxyapatite: Volume Assessment.

INTRODUCTION: The aim of this study was to assess the efficacy of using bone morphogenetic protein-2 with hydroxyapatite granules (BMP-2/hydroxyapatite) during augmentation of maxillary sinus floor, with respect to changes in volume, relative to conventional bone graft materials. METHOD AND MATERIALS: Twenty of 25 patients in the BMP-2/hydroxyapatite group, and 16 of 33 patients in the conventional materials group met the criteria for inclusion in this study. Computed tomography scans were performed preoperatively, immediately postoperatively, and at follow-up, approximately 6 months postoperatively. Changes in volume and height of both grafted materials were measured using 3-dimensional reconstruction software; these changes were compared between groups. RESULTS: The mean (standard deviation) volumetric changes were 0.25 (0.11) cc and -0.07 (0.35) cc, and the mean rates of volumetric changes were 26.44% (7.78%) and -2.92% (30.92%) in BMP-2/hydroxyapatite and conventional materials groups, respectively. The mean height changes were 0.34 (0.73) mm and -0.63 (1.07) mm, and the mean rates of height changes were 3.67% (7.57%) and -5.95% (9.98%) in BMP-2/hydroxyapatite and conventional materials groups, respectively. CONCLUSION: Compared with the conventional materials group, the BMP-2/hydroxyapatite group showed better maxillary sinus floor augmentation results in terms of volumetric changes and grafted material densities, and can provide predictably reliable outcomes.

The effect of two locally administered anti-resorptive agents on bone regeneration in a rat fibula model: Alendronate and 15-deoxy-Δ12,14-prostaglandin J2.

Bisphosphonates are well-known drugs as inhibitors of bone resorption acting on inducing programmed cell death of osteoclasts. However, many in vitro studies report that optimal concentration of the bisphosphonate affects not only osteoclasts but also osteoblasts, that is, it induces the anabolic effects of osteoblasts. Recently reported 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) is an endogenous ligand of peroxisome proliferator-activated receptor-gamma, with an inhibitory activity on bone loss. Researchers have also suggested that 15d-PGJ2 has the ability to reduce bone destruction and as the possibility of regeneration of bone. The purpose of this study is to demonstrate the anabolic effect of two anti-resorptive materials, alendronate and 15d-PGJ2, in a critical sized segmental defect model of rat fibula. The regenerated bone on the operative site was assessed through gross, radiographic (plain X-ray, and micro-computed tomography), histomorphologic evaluation, and statistical analysis. Consequently, the locally applied alendronate prevented resorption of grafted materials, and had a positive effect on bone regeneration with positive micro-architectural modification of the surrounding bone, although this study did not verify a significant capacity of bone regeneration of 15d-PGJ2 and instead only shed a light on its possibility.

Diagnostic Efficacy of 18F-FDG PET/MRI in Peripheral Nerve Injury Models.

The aim of this study was to evaluate the diagnostic efficacy of 18F-FDG PET/MRI in two different peripheral neuropathic pain models using the injured rat sciatic nerves. Twelve rats, with operation on left sciatic nerves, were evenly divided into three groups: sham surgery (control group), crushing injury and chronic constriction injury (CCI) (experimental groups). The nerve damage was assessed at 3 weeks postoperatively using following methods: paw withdrawal threshold values (RevWT), maximum standardized uptake values on PET/MRI images (SUVR), and counting the number of myelinated axons in proximal and distal sites of nerve injury (MAxR). The results were quantified and statistically analyzed. Compared to the control group, the crushing injury demonstrated significant differences in RevWT (p < 0.0001) and SUVR (p = 0.027) and the CCI group demonstrated significant differences in RevWT (p < 0.0001), SUVR (p = 0.001) and MAxR (p = 0.048). There were no significant differences between the two experimental groups for all assessments. Correlation analysis demonstrated that RevWT and SUVR assessments were highly correlated (r = -- 0.710, p = 0.010), and SUVR and MAxR were highly correlated (r = 0.611, p = 0.035). However, there was no significant correlation between RevWT and MAxR. The PET scan may be a valuable imaging modality to enable noninvasive, objective diagnosis of neuropathic pain caused by peripheral nerve injury. Also, MRI fused with PET may help clarify the anatomic location of soft tissue structures, including the peripheral nerves.

Considerations for Mandibular Reconstruction in the Pediatric Patient Following Resection of Malignant Tumors.

We recently achieved favorable results in 3 pediatric patients with mandibular osteosarcomas that were treated at our hospital, including with immediate reconstructive surgery performed after tumor resection. Based on a literature review and practical investigation, we discuss the considerations for mandibular reconstruction after malignant lesions are removed from the mandible in children. Mandibular reconstruction for pediatric patients requires an understanding of the changes in bone and soft-tissue architecture due to growth and development at both the donor and recipient sites. Immediate mandibular reconstruction with a free flap can be considered a reasonable option even for young children who require extensive mandibular surgery. However, the variables affecting decisions about treatment planning vary between the different conditions in individual patients, and moreover, these cases are not common in the pediatric population. Therefore, long-term follow-up treatment and further investigations are required for the optimized diagnosis, treatment, and prognosis of pediatric mandibular malignancies.

Perforation in Submucous Cleft Palate Due to Methotrexate-Induced Mucositis in a Patient With Rheumatoid Arthritis.

Spontaneous palatal perforation can be rarely developed by several causes, such as tumor, trauma, and infection. This article reports a patient with large mid-palatal perforation after suffering from severe oral mucositis, which occurred about a month after taking methotrexate (MTX) for rheumatoid arthritis. Through computed tomography and clinical examination, this patient was diagnosed with perforation in unrecognized submucous cleft palate (SMCP) due to drug-induced mucositis. After MTX discontinuation, the oral mucositis was almost healed completely in a month, and the hole was successfully closed by palatoplasty. The author can see that the palatal perforation can occur by oral complication of MTX in SMCP patient. It is an important awareness to dentists as the use of MTX continues to increase for antirheumatic therapy.

Stepwise verification of bone regeneration using recombinant human bone morphogenetic protein-2 in rat fibula model.

OBJECTIVES: The purpose of this study was to introduce our three experiments on bone morphogenetic protein (BMP) and its carriers performed using the critical sized segmental defect (CSD) model in rat fibula and to investigate development of animal models and carriers for more effective bone regeneration. MATERIALS AND METHODS: For the experiments, 14, 16, and 24 rats with CSDs on both fibulae were used in Experiments 1, 2, and 3, respectively. BMP-2 with absorbable collagen sponge (ACS) (Experiments 1 and 2), autoclaved autogenous bone (AAB) and fibrin glue (FG) (Experiment 3), and xenogenic bone (Experiment 2) were used in the experimental groups. Radiographic and histomorphological evaluations were performed during the follow-up period of each experiment. RESULTS: Significant new bone formation was commonly observed in all experimental groups using BMP-2 compared to control and xenograft (porcine bone) groups. Although there was some difference based on BMP carrier, regenerated bone volume was typically reduced by remodeling after initially forming excessive bone. CONCLUSION: BMP-2 demonstrates excellent ability for bone regeneration because of its osteoinductivity, but efficacy can be significantly different depending on its delivery system. ACS and FG showed relatively good bone regeneration capacity, satisfying the essential conditions of localization and release-control when used as BMP carriers. AAB could not provide release-control as a BMP carrier, but its space-maintenance role was remarkable. Carriers and scaffolds that can provide sufficient support to the BMP/carrier complex are necessary for large bone defects, and AAB is thought to be able to act as an effective scaffold. The CSD model of rat fibula is simple and useful for initial estimate of bone regeneration by agents including BMPs.