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Archives of Ophthalmology (Chicago,... Jan 1993Based on analyses in a series of 116 patients, we found that the response to strabismus surgery (degrees of change of ocular alignment per millimeter of rectus...
Based on analyses in a series of 116 patients, we found that the response to strabismus surgery (degrees of change of ocular alignment per millimeter of rectus recession) correlated significantly with the preoperative deviation for esotropic and exotropic patients. The prediction of response to strabismus surgery was not improved significantly with the inclusion of axial length, age, and/or preoperative refractive error beyond the prediction provided with use of only the preoperative deviation, even though we have previously suggested that the response to strabismus surgery should be related to axial length. We believed that larger eyes should have a smaller response for the same number of millimeters of surgery than smaller eyes. We now believe that although the response to strabismus surgery does correlate significantly and inversely with axial length, this correlation may not be clinically important given the much stronger influence of preoperative deviation.
Topics: Adolescent; Adult; Child; Child, Preschool; Esotropia; Exotropia; Eye; Humans; Infant; Oculomotor Muscles; Treatment Outcome
PubMed: 8424728
DOI: 10.1001/archopht.1993.01090010079030 -
AJNR. American Journal of Neuroradiology Jan 2006Carotid artery stenosis quantification uses percent diameter ratios from conventional angiography. Multidetector high-speed CT angiography (CTA) allows direct millimeter...
PURPOSE
Carotid artery stenosis quantification uses percent diameter ratios from conventional angiography. Multidetector high-speed CT angiography (CTA) allows direct millimeter measurement of carotid stenosis. We hypothesize a linear relationship between millimeter stenosis measurements and derived percent, alleviating cumbersome ratio calculations.
METHODS
Two neuroradiologists separately reviewed CTAs of 268 carotid arteries, blinded to other information. The narrowest portion of each carotid stenosis was measured in millimeters from axial source images. Distal internal carotid arteries (ICAs) were measured beyond the bulb, where walls are parallel. North American Symptomatic Carotid Endarterectomy Trial (NASCET)-style ratios were calculated for each ICA, except for suspected near-occlusions. Interobserver agreement was calculated for all measurements. Correlation coefficients were calculated comparing millimeter and derived percent stenosis, followed by regression analysis. Sensitivity and specificity values tested validity.
RESULTS
Interobserver agreement correlations were excellent, from 0.78 to 0.89 (2-tailed P = .01). Excellent reader correlation permitted averaging of millimeter stenosis and distal ICA measurements, which were then used to calculate mean percent stenosis. Stenosis assessment was confidently performed from source images even with calcification. Regression analysis of mean percent as a function of mean millimeter stenosis shows a linear relationship, correlating 1.3 mm to 70% and 2.2 mm to 50% NASCET-style stenosis (Pearson's correlation of -0.95; n = 136). Direct millimeter measurement defining severe stenosis (70% or greater) has sensitivity of 88.2%, specificity of 92.4%, and negative predicted value of 98.2%.
CONCLUSION
There is a linear relationship between millimeter carotid stenosis diameter and derived percent stenosis. This allows prediction of NASCET-type percent from millimeter stenosis.
Topics: Carotid Artery, Internal; Carotid Stenosis; Humans; Image Processing, Computer-Assisted; Imaging, Three-Dimensional; Observer Variation; Predictive Value of Tests; Sensitivity and Specificity; Tomography, X-Ray Computed
PubMed: 16418349
DOI: No ID Found -
Medical Physics Apr 2014The use of motion mitigation techniques such as tracking and gating in particle therapy requires real-time knowledge of tumor position with millimeter precision. The aim...
PURPOSE
The use of motion mitigation techniques such as tracking and gating in particle therapy requires real-time knowledge of tumor position with millimeter precision. The aim of this phantom-based study was to evaluate the option of diagnostic ultrasound (US) imaging (sonography) as real-time motion detection method for scanned heavy ion beam irradiation of moving targets.
METHODS
For this pilot experiment, a tumor surrogate was moved inside a water bath along two-dimensional trajectories. A rubber ball was used for this purpose. This ball was moved by a robotic arm in two dimensions lateral to the heavy ion beam. Trajectories having a period of 3 s and peak to peak amplitude of 20 mm were used. Square radiation fields of[Formula: see text] were irradiated on radiosensitive films with a 200 MeV/u beam of calcium ions having a FWHM of 6 mm. Pencil beam scanning and beam tracking were employed. The films were attached on the robotic arm and thus moved with the rubber ball. The position of the rubber ball was continuously measured by a US tracking system (Mediri GmbH, Heidelberg) and sent to the GSI therapy control system (TCS). This position was used as tracking vector. Position reconstruction from the US tracking system and data communication introduced a delay leading to a position error of several millimeters. An artificial neural network (ANN) was implemented in the TCS to predict motion from US measurements and thus to compensate for the delay.
RESULTS
Using ANN delay compensation and large motion amplitudes, the authors could produce irradiation patterns with a few percent inhomogeneity and about 1 mm geometrical conformity.
CONCLUSIONS
This pilot experiment suggests that diagnostic US should be further investigated as dose-free, high frame-rate, and model-independent motion detection method for scanning heavy ion beam irradiation of moving targets.
Topics: Heavy Ion Radiotherapy; Movement; Neoplasms; Neural Networks, Computer; Ultrasonography
PubMed: 24694128
DOI: 10.1118/1.4868459 -
Science Advances Oct 2023A three-dimensional (3D) holographic display (3DHD) can preserve all the volumetric information about an object. However, the poor fidelity of 3DHD constrains its...
A three-dimensional (3D) holographic display (3DHD) can preserve all the volumetric information about an object. However, the poor fidelity of 3DHD constrains its applications. Here, we present an ultrahigh-fidelity 3D holographic display that uses scattering for homogenization of angular spectrum. A scattering medium randomizes the incident photons and homogenizes the angular spectrum distribution. The redistributed field is recorded by a photopolymer film with numerous modulation modes and a half-wavelength scale pixel size. We have experimentally improved the contrast of a focal spot to 6 × 10 and tightened its spatial resolution to 0.5 micrometers, respectively ~300 and 4.4 times better than digital approaches. By exploiting the spatial multiplexing ability of the photopolymer and the transmission channel selection capability of the scattering medium, we have realized a dynamic holographic display of 3D spirals consisting of 20 foci across 1 millimeter × 1 millimeter × 26 millimeters with uniform intensity.
PubMed: 37824613
DOI: 10.1126/sciadv.adi9987 -
Science Advances Sep 2022The cochlea maps tones with different frequencies to distinct anatomical locations. For instance, a faint 5000-hertz tone produces brisk responses at a place...
The cochlea maps tones with different frequencies to distinct anatomical locations. For instance, a faint 5000-hertz tone produces brisk responses at a place approximately 8 millimeters into the 18-millimeter-long guinea pig cochlea, but little response elsewhere. This place code pervades the auditory pathways, where neurons have "best frequencies" determined by their connections to the sensory cells in the hearing organ. However, frequency selectivity in cochlear regions encoding low-frequency sounds has not been systematically studied. Here, we show that low-frequency hearing works according to a unique principle that does not involve a place code. Instead, sound-evoked responses and temporal delays are similar across the low-frequency regions of the cochlea. These findings are a break from theories considered proven for 100 years and have broad implications for understanding information processing in the brainstem and cortex and for optimizing the stimulus delivery in auditory implants.
Topics: Animals; Cochlea; Guinea Pigs; Hearing; Sound
PubMed: 36149949
DOI: 10.1126/sciadv.abq2773 -
Acta Biomaterialia May 2021Atomic force microscopy (AFM) has become a powerful tool for the characterization of materials at the nanoscale. Nevertheless, its application to hierarchical biological...
Atomic force microscopy (AFM) has become a powerful tool for the characterization of materials at the nanoscale. Nevertheless, its application to hierarchical biological tissue like cartilage is still limited. One reason is that such samples are usually millimeters in size, while the AFM delivers much more localized information. Here a combination of AFM and fluorescence microscopy is presented where features on a millimeter sized tissue sample are selected by fluorescence microscopy on the micrometer scale and then mapped down to nanometer precision by AFM under native conditions. This served us to show that local changes in the organization of fluorescent stained cells, a marker for early osteoarthritis, correlate with a significant local reduction of the elastic modulus, local thinning of the collagen fibers, and a roughening of the articular surface. This approach is not only relevant for cartilage, but in general for the characterization of native biological tissue from the macro- to the nanoscale. STATEMENT OF SIGNIFICANCE: Different length scales have to be studied to understand the function and dysfunction of hierarchically organized biomaterials or tissues. Here we combine a highly stable AFM with fluorescence microscopy and precisely motorized movement to correlate micro- and nanoscopic properties of articular cartilage on a millimeter sized sample under native conditions. This is necessary for unraveling the relationship between microscale organization of chondrocytes, micrometer scale changes in articular cartilage properties and nanoscale organization of collagen (including D-banding). We anticipate that such studies pave the way for a guided design of hierarchical biomaterials.
Topics: Cartilage, Articular; Chondrocytes; Elastic Modulus; Humans; Microscopy, Atomic Force; Osteoarthritis
PubMed: 33753314
DOI: 10.1016/j.actbio.2021.03.034 -
Lab on a Chip May 2022A recent trend in microfluidic microbial fuel cells (MFCs) is to exclude a separation membrane, instead, relying on the physics of laminar flow to maintain isolation...
A recent trend in microfluidic microbial fuel cells (MFCs) is to exclude a separation membrane, instead, relying on the physics of laminar flow to maintain isolation between anode and cathode compartments. To avoid solution crossover, the electrodes may be separated by distances of several millimeters, but this negatively affects the internal resistance and undermines a prime advantage of microscale MFCs. Therefore, we propose a facile method for synthesis of a micromembrane that supports sub-millimeter electrode spacing. Membrane synthesis reduces device fabrication complexity, and the proposed design avoids electrode contamination during its synthesis. Comparing results to a state-of-the-art membraneless MFC with 6 mm inter-electrode distances, the sub-millimeter membrane MFC under comparable flow conditions had an internal resistance that was 60% lower, power and current densities that were respectively 45% and 290% higher, and acetate conversion efficiencies that were 8 times higher. The enhanced flow stability provided stable operation under imbalanced flow conditions and delivered continuous increases to power density of up to 30% for flow rate increases of 100 times over baseline levels. As a result, maximum outputs obtained were 660 mW m and 3.5 A m. These are the highest reported for microfluidic MFCs using pure culture bacteria, which advances the goal of competing with mainstream MFC formats.
Topics: Bioelectric Energy Sources; Electricity; Electrodes; Microfluidics
PubMed: 35441185
DOI: 10.1039/d2lc00098a -
Nature Biotechnology Mar 2005Optical imaging of live animals has grown into an important tool in biomedical research as advances in photonic technology and reporter strategies have led to widespread... (Review)
Review
Optical imaging of live animals has grown into an important tool in biomedical research as advances in photonic technology and reporter strategies have led to widespread exploration of biological processes in vivo. Although much attention has been paid to microscopy, macroscopic imaging has allowed small-animal imaging with larger fields of view (from several millimeters to several centimeters depending on implementation). Photographic methods have been the mainstay for fluorescence and bioluminescence macroscopy in whole animals, but emphasis is shifting to photonic methods that use tomographic principles to noninvasively image optical contrast at depths of several millimeters to centimeters with high sensitivity and sub-millimeter to millimeter resolution. Recent theoretical and instrumentation advances allow the use of large data sets and multiple projections and offer practical systems for quantitative, three-dimensional whole-body images. For photonic imaging to fully realize its potential, however, further progress will be needed in refining optical inversion methods and data acquisition techniques.
Topics: Image Enhancement; Imaging, Three-Dimensional; Luminescent Measurements; Microscopy, Fluorescence; Photons; Tomography, Optical; Ultrasonography
PubMed: 15765087
DOI: 10.1038/nbt1074 -
The Angle Orthodontist Jul 2009To determine an appropriate threshold for clinically significant tooth-size discrepancy using both a Bolton standard deviation (SD) definition and a millimetric...
OBJECTIVE
To determine an appropriate threshold for clinically significant tooth-size discrepancy using both a Bolton standard deviation (SD) definition and a millimetric definition.
MATERIALS AND METHODS
Mesiodistal tooth widths were measured in 250 pretreatment dental casts of patients with Class I, Class II, and Class III malocclusions. The anterior and overall ratios and the required amount of maxillary and mandibular corrections were calculated. The casts were divided into small, normal, and large groups according to the anterior and overall ratios categorized by the Bolton SD definition, and into small, normal, and large groups according to the required amount of maxillary and mandibular corrections expressed in millimeters.
RESULTS
The small and large anterior ratio groups which fell under the category of the 2 SD threshold did not always need maxillary or mandibular corrections greater than 2 mm, while the small and large overall ratio groups always needed maxillary and mandibular corrections greater than 2 mm. The small and large maxillary correction groups in the 2 mm threshold category did not always have anterior or overall ratios greater than 2 SDs from the Bolton mean. However, the small and large mandibular correction groups always had anterior ratios greater than 2 SDs and did not always have overall ratios greater than 2 SDs.
CONCLUSIONS
The tooth-size discrepancies could be better expressed in terms of both percentage and actual amount of millimeters required for correction. The ratios outside 2 SDs from the Bolton mean and the discrepancies requiring more than 2 mm of maxillary and/or mandibular corrections are recommendable as the appropriate thresholds for clinical significance.
Topics: Female; Humans; Male; Malocclusion; Models, Dental; Odontometry; Reference Standards; Retrospective Studies; Tooth
PubMed: 19537863
DOI: 10.2319/070208-339.1 -
Neural Regeneration Research Aug 2024Nerve stimulation is a rapidly developing field, demonstrating positive outcomes across several conditions. Despite potential benefits, current nerve stimulation devices...
Nerve stimulation is a rapidly developing field, demonstrating positive outcomes across several conditions. Despite potential benefits, current nerve stimulation devices are large, complicated, and are powered via implanted pulse generators. These factors necessitate invasive surgical implantation and limit potential applications. Reducing nerve stimulation devices to millimetric sizes would make these interventions less invasive and facilitate broader therapeutic applications. However, device miniaturization presents a serious engineering challenge. This review presents significant advancements from several groups that have overcome this challenge and developed millimetric-sized nerve stimulation devices. These are based on antennas, mini-coils, magneto-electric and opto-electronic materials, or receive ultrasound power. We highlight key design elements, findings from pilot studies, and present several considerations for future applications of these devices.
PubMed: 38103235
DOI: 10.4103/1673-5374.389627