Automatic cochlear multimodal 3D image segmentation and analysis using atlas-model-based method

Objectives: To propose an automated fast cochlear segmentation, length, and volume estimation method from clinical 3D multimodal images which has a potential role in the choice of cochlear implant type, surgery planning, and robotic surgeries.

Methods: Two datasets from different countries were used. These datasets include 219 clinical 3D images of cochlea from 3 modalities: CT, CBCT, and MR. The datasets include different ages, genders, and types of cochlear implants. We propose an atlas-model-based method for cochlear segmentation and measurement based on high-resolution μCT model and A-value. The method was evaluated using 3D landmarks located by two experts.

Results: The average error was 0.61 ± 0.22 mm and the average time required to process an image was 5.21 ± 0.93 seconds (P<0.001). The volume of the cochlea ranged from 73.96 mm3 to 106.97 mm3 , the cochlear length ranged from 36.69 to 45.91 mm at the lateral wall and from 29.12 to 39.05 mm at the organ of Corti.

Discussion: We propose a method that produces nine different automated measurements of the cochlea: volume of scala tympani, volume of scala vestibuli, central lengths of the two scalae, the scala tympani lateral wall length, and the organ of Corti length in addition to three measurements related to A-value.

Conclusion: This automatic cochlear image segmentation and analysis method can help clinician process multimodal cochlear images in approximately 5 seconds using a simple computer. The proposed method is publicly available for free download as an extension for 3D Slicer software.

[Radiologic Imaging of Pediatric Hearing Loss]

Hearing loss in childhood has serious consequences for the entire development of the child. It is very important to make an accurate early diagnosis. The assessment usually includes physical, genetic, and radiological examination. In imaging diagnostics, CT, Cone Beam CT and or MRI of the petrous bone are the usual imaging modalities for the assessment of diseases of mastoid air cells, middle ear, external ear, the cochlea, the vestibulocochlear nerve, and the brain.

Automatic intra-subject registration and fusion of multimodal cochlea 3D clinical images

Background

The postoperative imaging assessment of Cochlear Implant (CI) patients is imperative. The main obstacle is that Magnetic Resonance imaging (MR) is contraindicated or hindered by significant artefacts in most cases with CIs. This study describes an automatic cochlear image registration and fusion method that aims to help radiologists and surgeons to process pre-and postoperative 3D multimodal imaging studies in cochlear implant (CI) patients.

Methods and findings

We propose a new registration method, Automatic Cochlea Image Registration (ACIR-v3), which uses a stochastic quasi-Newton optimiser with a mutual information metric to find 3D rigid transform parameters for registration of preoperative and postoperative CI imaging. The method was tested against a clinical cochlear imaging dataset that contains 131 multimodal 3D imaging studies of 41 CI patients with preoperative and postoperative images. The preoperative images were MR, Multidetector Computed Tomography (MDCT) or Cone Beam Computed Tomography (CBCT) while the postoperative were CBCT. The average root mean squared error of ACIR-v3 method was 0.41 mm with a standard deviation of 0.39 mm. The results were evaluated quantitatively using the mean squared error of two 3D landmarks located manually by two neuroradiology experts in each image and compared to other previously known registration methods, e.g. Fast Preconditioner Stochastic Gradient Descent, in terms of accuracy and speed.

Conclusions

Our method, ACIR-v3, produces high resolution images in the postoperative stage and allows for visualisation of the accurate anatomical details of the MRI with the absence of significant metallic artefacts. The method is implemented as an open-source plugin for 3D Slicer tool.

Stimulation of lysozyme release by selected microbial preparations

Lysozyme is an important factor of innate immunity and a unique enzybiotic in that it exerts not only antibacterial activity, but also antiviral, anti-inflammatory, anticancer, and immunomodulatory activities. The purpose of the present study was to investigate whether in vitro exposure to microbial preparations can affect the release and production of lysozyme activity in human monocytic cell line THP-1. Lysozyme activity levels in cell culture fluids were measured using highly sensitive fluorescence-based lysozyme activity assay. Different preparations of bacteria and ascomycetes stimulated lysozyme release result in a higher lysozyme activity after one hour exposure. The demonstrated ability of selected microbial preparations to enhance the release of lysozyme activity can present a new mechanism contributing to explaining biological characteristics of microbial preparations, including their antibacterial and immune-stimulating properties.

Determination of lysozyme activity by a fluorescence technique in comparison with the classical turbidity assay

The aim of this comparable study was to evaluate two different methods for the assay of lysozyme activity. Lysozyme activity was assayed by turbidimetric and fluorescence-based methods with hen egg white lysozyme as standard. The standard activity of each assay was calibrated in units of activity per mg under the experimental conditions (37 degrees C) so that direct comparison between these two assays could be made. The turbidimetric assay was performed using a 0.36 mg/ml Micrococcus lysodeikticus suspension and a microtiter plate reader capable of analyzing enzyme kinetics at 450 nm, and the linearity, in the range of 2.3-23.8 units/ml, presented a correlation coefficient (R2) as high as 0.9967. The fluorescence-based assay was performed with EnzChek kit using a suspension of Micrococcus lysodeikticus labeled with fluorescein and a fluorescence microplate reader. The linearity in the range of 0.47-5.28 units/ml, presented a correlation coefficient (R2) as high as 0.9881. Thus, the turbidimetric assay provides a simple rapid accurate and specific method for the determination of lysozyme activity but with relatively low sensitivity in comparison with the fluorescence-based method which was demonstrated to be a high sensitivity assay, and hence a reliable applicable technique to determine lysozyme activity at low levels e.g. in cell culture systems.

Hemodynamic effects of external continuous negative pressure ventilation compared with those of continuous positive pressure ventilation in dogs with acute lung injury

Patients with noncardiogenic pulmonary edema requiring ventilatory assistance are usually supported with CPPV using positive end-expiratory pressure (PEEP), but CPPV requires endotracheal intubation and may decrease cardiac output (QT). The purpose of this study was to examine thoracoabdominal continuous negative pressure ventilation (CNPV) using external negative end-expiratory pressure (NEEP). The effects on gas exchange and hemodynamics were compared with those of CPPV with PEEP, with the premise that CNPV might sustain venous return and improve QT. In 6 supine, anesthetized and paralyzed dogs with oleic-acid-induced pulmonary edema, 30 min of CNPV was alternated twice with 30 min of CPPV. Positive and negative pressure ventilation were carefully matched for fractional inspired oxygen concentration (FIO2 = 0.56), breathing frequency, and tidal volume. In addition, we matched the increase in delta FRC obtained with the constant distending pressures produced by both modes of ventilation. An average of -9 cm H2O of NEEP produced the same delta FRC as 10.8 cm H2O of PEEP. Gas exchange did not differ significantly between the 2 modes. However, QT was 15.8% higher during CNPV than during CPPV (p less than 0.02). Mixed venous oxygen saturation also improved during CNPV compared with that during CPPV (58.3 versus 54.5%, p less than 0.01). Negative pressure ventilation using NEEP may be a viable alternative to positive pressure ventilation with PEEP in the management of critically ill patients with noncardiogenic pulmonary edema. It offers comparable improvement in gas exchange with the advantages of less cardiac depression and the possible avoidance of endotracheal intubation.