Blood perfusion is the supply of tissue with blood, and oxygen is a key factor in the field of minor and major wound healing. Reduced perfusion of a wound bed or transplant often causes various complications. Reliable methods for an objective evaluation of perfusion status are still lacking, and insufficient perfusion may remain undiscovered, resulting in chronic processes and failing transplants. Hyperspectral imaging (HSI) represents a novel method with increasing importance for clinical practice. Therefore, methods, software and algorithms for a new HSI system are presented which can be used to observe tissue oxygenation and other parameters that are of importance in supervising healing processes. This could offer an improved insight into wound perfusion allowing timely intervention.
Chemical and physical processing of allografts is associated with a significant reduction in biomechanics. Therefore, treatment of tissue with high hydrostatic pressure (HHP) offers the possibility to devitalize tissue gently without changing biomechanical properties. To obtain an initial assessment of the effectiveness of HHP treatment, human osteoblasts and chondrocytes were treated with different HHPs (100–150 MPa, 250–300 MPa, 450–500 MPa). Devitalization efficiency was determined by analyzing the metabolic activity via WST-1(water-soluble tetrazolium salt) assay. The type of cell death was detected with an apoptosis/necrosis ELISA (enzyme-linked immune sorbent assay) and flow cytometry. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) were carried out to detect the degree of cell destruction. After HHP treatment, the metabolic activities of both cell types decreased, whereas HHP of 250 MPa and higher resulted in metabolic inactivation. Further, the highest HHP range induced mostly necrosis while the lower HHP ranges induced apoptosis and necrosis equally. FESEM and TEM analyses of treated osteoblasts revealed pressure-dependent cell damage. In the present study, it could be proven that a pressure range of 250–300 MPa can be used for cell devitalization. However, in order to treat bone and cartilage tissue gently with HHP, the results of our cell experiments must be verified for tissue samples in future studies.
Objectives
Knowledge about cochlear duct length (CDL) may assist electrode choice in cochlear implantation (CI). However, no gold standard for clinical applicable estimation of CDL exists. The aim of this study is (1) to determine the most reliable radiological imaging method and imaging processing software for measuring CDL from clinical routine imaging and (2) to accurately predict the insertion depth of the CI electrode.
Methods
Twenty human temporal bones were examined using different sectional imaging techniques (high-resolution computed tomography [HRCT] and cone beam computed tomography [CBCT]). CDL was measured using three methods: length estimation using (1) a dedicated preclinical 3D reconstruction software, (2) the established A-value method, and (3) a clinically approved otosurgical planning software. Temporal bones were implanted with a 31.5-mm CI electrode and measurements were compared to a reference based on the CI electrode insertion angle measured by radiographs in Stenvers projection (CDLreference).
Results
A mean cochlear coverage of 74% (SD 7.4%) was found. The CDLreference showed significant differences to each other method (p < 0.001). The strongest correlation to the CDLreference was found for the otosurgical planning software-based method obtained from HRCT (CDLSW-HRCT; r = 0.87, p < 0.001) and from CBCT (CDLSW-CBCT; r = 0.76, p < 0.001). Overall, CDL was underestimated by each applied method. The inter-rater reliability was fair for the CDL estimation based on 3D reconstruction from CBCT (CDL3D-CBCT; intra-class correlation coefficient [ICC] = 0.43), good for CDL estimation based on 3D reconstruction from HRCT (CDL3D-HRCT; ICC = 0.71), poor for CDL estimation based on the A-value method from HRCT (CDLA-HRCT; ICC = 0.29), and excellent for CDL estimation based on the A-value method from CBCT (CDLA-CBCT; ICC = 0.87) as well as for the CDLSW-HRCT (ICC = 0.94), CDLSW-CBCT (ICC = 0.94) and CDLreference (ICC = 0.87).
Conclusions
All approaches would have led to an electrode choice of rather too short electrodes. Concerning treatment decisions based on CDL measurements, the otosurgical planning software-based method has to be recommended. The best inter-rater reliability was found for CDLA-CBCT, for CDLSW-HRCT, for CDLSW-CBCT, and for CDLreference.
Key Points
• Clinically applicable calculations using high-resolution CT and cone beam CT underestimate the cochlear size.
• Ten percent of cochlear duct length need to be added to current calculations in order to predict the postoperative CI electrode position.
• The clinically approved otosurgical planning software-based method software is the most suitable to estimate the cochlear duct length and shows an excellent inter-rater reliability.
Purpose. We present a case of a bilateral postoperative maxillary cyst (PMC) and discuss this with a systemic review. Case Report and Literature Review. A 68-year-old female with pain and swelling on the right side of the face. MRI and CT showed a cystic tumors of the right and left maxillary sinus. Radical maxillary surgery via a Caldwell-Luc procedure had been performed 55 years ago and bilateral PMC was diagnosed. The PubMed database was searched for PMC within the last 30 years. Results. Together with the current case, we found 23 reports including 284 patients describing PMC. It was diagnosed at a mean time of 22 years after causal surgery at a mean age of 47 years. Initial symptoms were mostly pain with or without swelling. The main radiological sign was a unilocular radiolucency with a slight preference for the left side. Discussion. PMC is a long-term complication that can occur after maxillary sinus surgery and a second surgical approach is required in order to stop cystic expansion. Therefore, patients' informed consent on this complication as well as a prolonged follow-up is recommended. Simple paranasal ultrasound or paranasal sinus plain radiography may lead to an earlier detection reducing interventional morbidity.
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