Effects of object‐to‐detector distance and beam energy on synchrotron radiation phase‐contrast imaging of implanted cochleae
Bibliographic record
Abstract
Summary Objectives To demonstrate that synchrotron radiation phase‐contrast imaging (SR‐PCI) can be used to visualize the intrascalar structures in implanted human cochleae and to find the optimal combination of the parameters object‐to‐detector distance (ODD) and beam energy (E) for visualization. Materials and Methods Three cadaveric implanted human temporal bones underwent SR‐PCI with varying combinations of parameters ODD (3, 2 and 1 m) and E (47, 60 and 72 keV). All images were then reconstructed to a three‐dimensional (3D) stack of slices. The acquired 3D images were compared using contrast‐to‐noise ratios (CNRs) of the basilar membrane ( ) and the electrode array (CNRE) and the standard deviation of the beam streaks ( ). Postprocessing calculations were performed using Matlab (Version 2017b, MathWorks Inc., Natick, MA, U.S.A.) with a standard significance level p < 0.05 to determine the most optimal combination of parameters. Results SR‐PCI with computed tomography reconstruction provided good visualization of the anatomical features of the implanted cochleae, specifically the exact location of the electrode with respect to the BM. A single‐factor ANOVA revealed a significant difference of variance for both CNRE and CNRBM, but failed to show significance for . A two‐sample t‐test failed to show any significant difference between CNRE columns of (3 m, 72 keV) and (2 m, 60 keV). The CNRBM was significantly different only at two pairs of columns, when (1 m, 72 keV) was compared against (2 m, 72 keV) and (3 m, 72 keV). Conclusions The results of this study show that SR‐PCI is a viable method to visualize implanted human cochleae. SR‐PCI is less invasive, less labour intensive and is associated with a much lower acquisition time compared to other methods for postimplantation imaging in humans, such as histological sectioning. We found that the optimal combination of E and ODD parameters was 72 keV and 2 m, respectively. These parameters resulted in high‐contrast images of the electrode as well as all internal structures of the cochleae. Lay Description Cochlear implants (CI) are currently the preferred method of treatment for hearing loss. Cochlear implantation surgery involves placement of a metallic, wire‐shaped electrode inside the cochlea, the main organ of the human hearing system. Knowledge of the exact location of the electrode after implantation is beneficial in improving the extent of restored hearing. Common clinical imaging modalities such as computed‐tomography (CT) are not ideal for providing such information, due to lack of resolution and streaking caused by the metallic electrode. Recent studies have developed algorithms to extract the electrode location from clinical computed‐tomography images and have been validated using histology or micro computed‐tomography (micro‐CT). Synchrotron radiation phase contrast imaging (SR‐PCI) is a high‐resolution imaging technique used to visualize small structures in three dimensions. Recently, SR‐PCI has been shown to be an alternative to histology or micro‐CT for imaging the human cochlea. However, it has not been optimized for imaging implanted human cochleae. The main objective of the present work was to find the optimal organization of imaging parameters (i.e., object‐to‐detector distance and beam energy) for using SR‐PCI to image implanted human cochleae. Three cadaveric human cochleae were imaged using five different combinations of imaging parameters at the Canadian Light Source Inc., Saskatoon, SK, Canada. The resulting images were compared both quantitatively and qualitatively. An optimal combination of parameters was found to produce high‐contrast images of the both the CI electrode and all internal structures of the cochlea with minimal streaking. SR‐PCI is therefore a viable alternative to histological or micro‐CT studies for post‐surgical imaging of implanted human cochleae.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".