Measurement Modalities Research Articles

Impact of Coleman Block Test on Adult Hindfoot Alignment Assessed by Clinical Examination, Radiography, and Weight-Bearing Computed Tomography.

Background:Cavovarus foot constitutes a complex 3-dimensional deformity. The Coleman block test has traditionally been used to distinguish between forefoot- and hindfoot-driven deformity. However, there has been no objective evaluation of the Coleman block test using radiographs or weightbearing computed tomography (WBCT). The purpose of this study was to compare hindfoot alignment in adult cavovarus feet with and without the Coleman block using clinical examination, radiography, and WBCT.Methods:Six feet in 6 patients with a clinical diagnosis of cavovarus foot deformity were prospectively enrolled. All feet underwent clinical photography with the camera positioned at 0 degrees to the heel, hindfoot alignment view radiography with the beam positioned 20 degrees off the ground, and WBCT, both with and without the Coleman block in place. Clinical photos were characterized using the standing talocalcaneal angle (STCA), radiographs were characterized using the hindfoot alignment angle (HAA), and WBCTs were characterized using manual and automated hindfoot alignment angle (HAA) and foot and ankle offset (FAO). Using paired analyses, measurements taken with the Coleman block in place were compared to those taken without the Coleman block. Finally, the different methods of measuring hindfoot alignment were tested for correlation with each other. Mean age was 56 years (range 38-69).Results:On clinical photography, the STCA decreased by 3.8 degrees with addition of the block (from 10.0±6.6 degrees varus without block to 6.2±7.1 degrees varus with block; P = .001). On radiograph, HAA decreased by 9.0 degrees with addition of the block (from 16.8±8.4 degrees varus without block to 7.5±6.3 degrees varus with block; P = .07). On WBCT, hindfoot alignment angle changed an average of 3.2 degrees (33.4 degrees varus without block, 30.2 degrees varus with block; P = .008). On WBCT, FAO decreased by 1.4% (from 11.3% varus without block to 10.1% varus with block; P = .003). Clinical examination and automated WBCT measurements were strongly correlated with each other.Conclusion:Clinical examination, radiograph, and WBCT demonstrated improvements in hindfoot varus using the Coleman block test in adults, but no patient demonstrated complete resolution of deformity regardless of the measurement modality. Clinical examination correlated strongly with automated WBCT measurements.Level of Evidence:Level IV, retrospective case review.

The impact of limb loading and the measurement modality (2D versus 3D) on the measurement of the limb loading dependent lower extremity parameters

BackgroundDeformity assessment and preoperative planning of realignment surgery are conventionally based on weight-bearing (WB) radiographs. However, newer technologies such as three-dimensional (3D) preoperative planning and surgical navigation with patient-specific instruments (PSI) rely on non-weight bearing (NWB) computed tomography (CT) data. Additionally, differences between conventional two-dimensional (2D) and 3D measurements are known. The goal of the present study was to systematically analyse the influence of WB and the measurement modality (2D versus 3D) on common WB-dependent measurements used for deformity assessment.Methods85 lower limbs could be included. Two readers measured the hip-knee-ankle angle (HKA) and the joint line convergence angle (JLCA) in 2D WB and 2D NWB radiographs, as well as in CT-reconstructed 3D models using an already established 3D measurement method for HKA, and a newly developed 3D measurement method for JLCA, respectively. Interrater and intermodality reliability was assessed.ResultsSignificant differences between WB and NWB measurements were found for HKA (p < 0.001) and JLCA (p < 0.001). No significant difference could be observed between 2D HKA NWB and 3D HKA (p = 0.09). The difference between 2D JLCA NWB and 3D JLCA was significant (p < 0.001). The intraclass correlation coefficient (ICC) for the interrater agreement was almost perfect for all HKA and 3D JLCA measurements and substantial for 2D JLCA WB and 2D JLCA NWB. ICC for the intermodality agreement was almost perfect between 2D HKA WB and 2D HKA NWB as well as between 2D HKA NWB and 3D HKA, whereas it was moderate between 2D JLCA WB and 2D JLCA NWB and between 2D JLCA NWB and 3D JLCA.ConclusionLimb loading results in significant differences for both HKA and JLCA measurements. Furthermore, 2D projections were found to be insufficient to represent 3D joint anatomy in complex cases. With an increasing number of surgical approaches based on NWB CT-reconstructed models, research should focus on the development of 3D planning methods that consider the effects of WB on leg alignment.

0825 Sleep During Pregnancy Through One Year Postpartum: Correspondence Between Actigraphy and Self-Report Measures

Abstract Introduction Disrupted sleep and shorter sleep duration is common in pregnancy, due to hormonal changes and physical discomfort, and in postpartum due to new infants. Objective data in this population studied over more than one year are lacking. The current analysis focuses on actigraphy-based and self-reported sleep. We examined the level of correspondence between these two complementary measurement modalities. Methods Pregnant women were enrolled in the Stress and Health in Pregnancy and Postpartum (SHIPP) study. Study visits were conducted from 2016-2019 during the 3rd trimester, 4-6 weeks postpartum, and 4 months, 8 months, and 12 months postpartum. Participants completed the Pittsburgh Sleep Quality Index (PSQI) and provided wrist-actigraphy data (Actiwatch, Philips Respironics) for one week prior to each study visit. Actigraphy-based time in bed (TIB), total sleep time (TST), sleep efficiency (SE), WASO and sleep latency (SL) were calculated. Correlations were conducted between actigraphy-based and self-reported PSQI sleep measures. Results 79 women (28.9±4.6 years) provided complete actigraphy data (≥3 valid days; 6.4±1.0 days) for at least one time point. Objective TST from the 3rd trimester to 12-months postpartum was 7.19, 6.87, 6.86, 6.89, and 6.78 hours, respectively. Actigraphy-based TIB was positively correlated with self-reported TIB at all five visits (r’s: 0.37-0.62, p’s&amp;lt;0.01). Actigraphy-based TST was positively correlated with self-reported TST (r’s: 0.27-0.48, p’s&amp;lt;0.05) at all visits. Actigraphy-based SE was negatively correlated with the PSQI Global Score at 4, 8, and 12 months postpartum (r’s: -0.29 to -0.39, p’s&amp;lt;0.05). Of note, actigraphy-based WASO and SL were not consistently correlated with any self-reported PSQI sleep measures. Conclusion Ensuring collection of accurate sleep data during pregnancy and postpartum is important, as poor sleep is associated with negative health outcomes for both mother and child. Self-reported data is common in large, epidemiologic studies yet actigraphy-based measures may capture different aspects of sleep than self-report. Support This study was supported by the National Institutes of Health (R01 NR01366).

Fast pulsatile blood flow measurement in deep tissue through a multimode detection fiber.

.Significance: Noninvasive in vivo fast pulsatile blood flow measurement in deep tissue is important because the blood flow waveform is correlated with physiological parameters, such as blood pressure and elasticity of blood vessels. Compromised blood flow may cause diseases, such as stroke, foot ulcer, and myocardial ischemia. There is great clinical demand for a portable and cost-effective device for noninvasive pulsatile blood flow measurement.Aim: A diffuse-optics-based method, diffuse speckle pulsatile flowmetry (DSPF), was developed for fast measurement () of deep tissue blood flow noninvasively. To validate its performance, both a phantom experiment and in vivo demonstration were conducted.Approach: Over the past two decades, single-mode fibers have been used as detection fibers in most diffuse-optics-based deep tissue blood flow measurement modalities. We used a multimode (MM) detection fiber with a core size of for diffused speckle pattern detection. A background intensity correction algorithm was implemented for speckle contrast calculation. The MM detection fiber helped to achieve a level of deep tissue blood flow measurement similar to that of conventional modalities, such as diffuse correlation spectroscopy and diffuse speckle contrast analysis, but it increases the measurement rate of blood flow to 300 Hz.Results: The design and implementation of the DSPF system were introduced. The theory of the background intensity correction for the diffused speckle pattern detected by the MM fiber was explained. A flow phantom was built for validation of the performance of the DSPF system. An in vivo cuff-induced occlusion experiment was performed to demonstrate the capability of the proposed DSPF system.Conclusions: An MM detection fiber can help to achieve fast () pulsatile blood flow measurement in the proposed DSPF method. The cost-effective device and the fiber-based flexible probe increase the usability of the DSPF system significantly.

Fast Nondestructive Battery Diagnostics with MRI and Magnetometry: Detect State of Health, State of Charge, and Current Distributions

Rechargeable batteries are notoriously difficult to assess. We are presenting new battery assessment technology based on MRI and magnetometry techniques, which allow non-destructive scanning of rechargeable cells. The techniques are fast, can detect changes in the electrode chemistry that occur as the battery is charged and discharged, or sense a range of different defects at early stages. In particular, we can determine site-resolved state-of-charge (where charge is stored in the cell), current distributions, as well as tiny transient effects. The vision is to use a benchtop-type instrument, which could be deployed in a variety of ways. The aim is to improve safety and performance, help in predicting battery life, clarify failure modes, and aid in the development of next-generation cells. Both MRI and magnetometry provide complementary measurement modalities with their strengths and limitations. MRI allows sensitive state of charge determination in a localized manner, and magnetometry allows to detect extremely weak electrical currents, both DC and AC at the level of nA in principle. Both these techniques provide new opportunities for battery diagnostics and research and could help reducuing the development cycle for new batteries and determining obscure battery failure modes. Figure 1

Brief Report: Performance-Based Executive Functioning Abilities are Associated with Caregiver Report of Adaptive Functioning in Autism Spectrum Disorder.

Executive functioning is thought to contribute to adaptive behavior skills development in individuals with autism spectrum disorder (ASD). However, supporting data are largely based on caregiver reports of executive functioning. The current study evaluated whether performance-based measures of executive functioning (working memory and inhibition) explained unique variance in parent-reported adaptive functioning among youth with ASD without an intellectual disability. Both spatial and verbal working memory were associated with adaptive functioning, particularly communication and daily living skills. Our findings demonstrate a robust relationship between working memory and adaptive functioning that translates across different measurement modalities. This preliminary study highlights that targeting executive functioning may be a critical component of an adaptive function training program.

Relationship of Surface Mechanomyography to Force Production in an Assessment of Gastrocnemius Muscle Contraction

PURPOSEEfficient gastrocnemii force production is essential for performance of functional activities such as stair ascent/descent and athletic activities involving jumping or running. Appropriate neuromuscular control and timing of gastrocnemius contraction is also important for fatigue and injury prevention. Hand Held Dynamometry (HHD) is the clinical standard for assessing force production during a muscle contraction. However, HHD is unable to provide precise timing data on the muscle activation responsible for force generation or monitor fatigue during an activity. Surface mechanomyography (sMMG) sensors are novel wearable devices that can be applied across a muscle group to provide a measurement of physical muscle output during a contraction. The purpose of this study is 1) to assess the relationship of sMMG’s muscle bulk displacement measurement to force generation and 2) to confirm sMMG detection of gastrocnemius contraction compared to the clinical timing standard of electromyography (EMG).METHODSHealthy, athletic individuals (mean age= 32.56 ±10.57 y, n= 9, 7 males, 2 females) underwent a neuromuscular control assessment of the gastrocnemius. Subjects performed a series of 3 resisted “make‐test” isometric holds with the right leg supported on an exam table and the ankle plantar flexed at 90 degrees against a hand‐held dynamometer with simultaneous EMG and sMMG recording. The third trial was selected for analysis when available. EMG data was processed with a 6th order low‐pass Butterworth filter and a Teager‐Kaiser energy operator function. A threshold for detecting the time points of gastrocnemius activation and deactivation was set at 3 standard deviations of a resting calibration trial above the minimum value for each measurement modality. The relationship of sMMG signal output for physical muscle displacement was compared to muscle contraction force output via HHD and timing measured via EMG using paired T‐tests and a Pearson correlation.RESULTSPeak gastrocnemius muscle bulk displacement detected by sMMG (mean= 7.65 ±2.68 mm) positively correlated with maximum force generation detected by HHD during isometric contraction (mean= 58.43 ±13.12 lb), r2= 0.669. The duration of gastrocnemius muscle contraction during the isometric hold activity did not differ significantly between SMG (mean= 4.71 ±1.17 s) and EMG (mean= 4.53 ±1.17 s), p= 0.273.CONCLUSIONSCorrelation between HHD and sMMG support the findings that increased physical muscle bulk displacement of the gastrocnemius was associated with greater force production during a contraction. The similarity to EMG timing reinforces the ability of the sMMG sensor to consistently detect active gastrocnemius contraction without complex signal processing (Figure 1). sMMG sensors may be a useful measurement tool for assessment of gastrocnemius functional performance during neuromuscular control screenings for injury prevention and rehabilitation.Example comparison of signal output during a resisted isometric gastrocnemius hold between a hand‐held dynamometer [HHD, (A)], surface mechanomyography [sMMG, (B)], and electromyography [EMG, (C)]. Greenand redXs indicate calculated muscle activation and deactivation time points based on 3 standard deviations of a resting calibration trial above the minimum for each modality (Solonik et al., 2010).Figure 1

Relationships between perfectionism, self-report impulsivity measures and delay discounting.

Perfectionism and impulsivity are multidimensional constructs. While different perfectionism dimensions are exclusively measured through self-reports, different impulsivity dimensions can be measured through self-report or behaviour via preferences for different rewards. This study explored differential associations between perfectionism and impulsivity based on both dimension and measurement modality (self-report/behavioural). We then examined whether adaptive or maladaptive perfectionism would be differentially associated with impulsivity. Two-hundred and six students completed two perfectionism and three impulsivity measures (two self-report; one behavioural). Two self-report impulsivity measures were associated with specific perfectionism dimensions, whereas the behavioural measure was not associated with perfectionism. Maladaptive perfectionism was associated with decreasing impulsivity, whereas adaptive perfectionism was associated with increasing impulsivity. Perfectionism related to impulsivity differently depending on how each construct was measured.

Neural magnetic field dependent fMRI toward direct functional connectivity measurements: A phantom study

Recently, the main issue in neuroscience has been the imaging of the functional connectivity in the brain. No modality that can measure functional connectivity directly, however, has been developed yet. Here, we show the novel MRI sequence, called the partial spinlock sequence toward direct measurements of functional connectivity. This study investigates a probable measurement of phase differences directly associated with functional connectivity. By employing partial spinlock imaging, the neural magnetic field might influence the magnetic resonance signals. Using simulation and phantom studies to model the neural magnetic fields, we showed that magnetic resonance signals vary depending on the phase of an externally applied oscillating magnetic field with non-right flip angles. These results suggest that the partial spinlock sequence is a promising modality for functional connectivity measurements.

Effectiveness of elevated vacuum and suction prosthetic suspension systems in managing daily residual limb fluid volume change in people with transtibial amputation

Previous studies investigating limb volume change with elevated vacuum have shown inconsistent results and have been limited by out-of-socket volume measurements and short, single-activity protocols. To evaluate the effectiveness of elevated vacuum for managing limb fluid volume compared to suction suspension with an in-socket measurement modality during many hours of activity. Fixed-order crossover design with a standardized out-of-laboratory activity protocol. Transtibial electronic elevated vacuum users participated in two sessions. Elevated vacuum was used during the first session, and suction suspension in the second. Participants completed a 5.5-h protocol consisting of multiple intervals of activity. In-socket residual limb fluid volume was continuously measured using a custom portable bioimpedance analyzer. A total of 12 individuals participated. Overall rate of fluid volume change was not significantly different, though the rate of posterior fluid volume change during Cycle 3 was significantly lower with elevated vacuum. Although individual results varied, 11 participants experienced lower overall rates of fluid volume loss in at least one limb region using elevated vacuum. Elevated vacuum may be more effective as a volume management strategy after accumulation of activity. Individual variation suggests the potential to optimize the limb fluid volume benefits of elevated vacuum by reducing socket vacuum pressure for some users. A better understanding of how elevated vacuum (EV) affects residual limb fluid volume will allow prosthetists to make more informed clinical decisions regarding accommodation strategies designed to improve daily socket fit.

Disk Area Is a More Reliable Measurement Than Anteroposterior Length in the Assessment of Lumbar Disk Herniations: A Validation Study.

Retrospective study. The goal of this study is to identify and validate the reliability and accuracy of 2 methods used to assess lumbar disk herniations (LDHs): anteroposterior length and cross-sectional area. Many clinicians characterize LDHs through the measurement of the anteroposterior length in the axial plane. Radiologists, on the other hand, have utilized software to measure the disk and canal areas to define the injury. In this study, the authors consider the reliability and accuracy of anteroposterior length in comparison with the area. Using International Classification of Diseases, 10th Revision (ICD-10) code M51.26, patients at a single academic medical center who received a diagnosis of primary lumbar radicular pain with subsequent magnetic resonance imaging documentation of a single-level disk herniation in 2015 and 2016 were identified. AGFA-IMPACS software was utilized to make the following measurements: anterior-posterior canal length; anterior-posterior disk length; mid-canal width; mid-disk width; total canal area; total disk area. Data analysis was conducted in SPSS and a 2-tailed reliability analysis using Cronbach alpha as a measure of reliability was obtained. A total of 408 patients met the inclusion and exclusion criteria for this study. Sixteen (3.9%) had L3-L4 herniation, 208 had L4-L5 herniation (51.0%), and 184 had L5-S1 herniation (47.5%). The least reliable interobserver metrics, with respective Cronbach alpha values of 0.381 and 0.659, were the linear measurements of mid-disk width and anterior-posterior canal length. Area measurements of the disk and canal areas generated Cronbach alpha values of 0.707 and 0.863. Intraobserver Cronbach alpha values for all measurements, including all areas and lengths, met or exceeded 0.982. The cross-sectional area provides a more reliable measurement modality for diskLDHs in comparison to linear measurements. Unlike anteroposterior length, cross-sectional area incorporates the shape of a herniation or canal in its measurement. Thus, it is superior in its characterization LDH particularly in light of its stronger reproducibility. Level III-retrospective study.

Single-particle spectroscopy for functional nanomaterials.

Tremendous progress in nanotechnology has enabled advances in the use of luminescent nanomaterials in imaging, sensing and photonic devices. This translational process relies on controlling the photophysical properties of the building block, that is, single luminescent nanoparticles. In this Review, we highlight the importance of single-particle spectroscopy in revealing the diverse optical properties and functionalities of nanomaterials, and compare it with ensemble fluorescence spectroscopy. The information provided by this technique has guided materials science in tailoring the synthesis of nanomaterials to achieve optical uniformity and to develop novel applications. We discuss the opportunities and challenges that arise from pushing the resolution limit, integrating measurement and manipulation modalities, and establishing the relationship between the structure and functionality of single nanoparticles.

The Potential of Stereotactic-EEG for Brain-Computer Interfaces: Current Progress and Future Directions.

Stereotactic electroencephalogaphy (sEEG) utilizes localized, penetrating depth electrodes to measure electrophysiological brain activity. It is most commonly used in the identification of epileptogenic zones in cases of refractory epilepsy. The implanted electrodes generally provide a sparse sampling of a unique set of brain regions including deeper brain structures such as hippocampus, amygdala and insula that cannot be captured by superficial measurement modalities such as electrocorticography (ECoG). Despite the overlapping clinical application and recent progress in decoding of ECoG for Brain-Computer Interfaces (BCIs), sEEG has thus far received comparatively little attention for BCI decoding. Additionally, the success of the related deep-brain stimulation (DBS) implants bodes well for the potential for chronic sEEG applications. This article provides an overview of sEEG technology, BCI-related research, and prospective future directions of sEEG for long-term BCI applications.

Effects of zinc oxide filler on the curing and mechanical response of alkyd coatings

The mechanical properties of an alkyd resin filled with zinc oxide pigment were studied at different concentrations over a wide range of time scales using dynamic mechanical analysis, quartz crystal rheometry and nanoindentation. The motivation for this work stems from the interest in accessing the long-term properties of paint coatings by studying the mechanical properties of historic paints. In this foundational work, we compare three different modalities of mechanical measurements and systematically determine the effect of pigment filler loading on the measured properties. Quantitative agreement between the methods is obtained when the characteristic time scales of each of the methods is taken into account. While nanoindentation is the technique most readily applied to historic paint samples, the rheometric quartz crystal microbalance (rheo-QCM) is the best suited for obtaining mechanistic information from measurements of paint properties over time, provided that appropriate thin-film samples can be produced. In these studies we find that ZnO increases the rate of oxidation of the alkyd during the initial stages of cure by an amount that depends on the ZnO content.

A review and preview of developments in the measurement of sociability.

Sociability is a complex, multifactorial trait. Its importance is underscored by a multitude of negative physical and mental health effects related to loneliness and social isolation. However, current measures of sociability primarily rely on subjective recall and self- report, which have inherent weaknesses and limitations. Although objective and automatic measurements could help to avoid some of these issues, they are still in early stages of development. In this article, the authors review past and present methods of measuring sociability and social interactions. This encompasses both subjective and objective subsets of qualitative and quantitative measurement modalities to gain a broader, more accurate perspective on sociability. Through an analysis of advantages and disadvantages of measurement methods within these categories, a foundational knowledge of sociability measurement can be understood. Utilizing current technology and research methods holds promise to more accurately represent individuals' social networks and social patterns.

REPRINTED WITH PERMISSION OF IASP – PAIN 160 (2019) 1494–1501: Migraine understood as a sensory threshold disease

Migraine encompasses a broader spectrum of sensory symptoms than just headache. These “other” symptoms, eg, sensory phobias, cognitive and mood changes, allodynia, and many others indicate an altered sensitivity to sensory input which can be measured, in principle, by quantifying sensory threshold changes longitudinally over time. Photophobia, for example, can be quantified by investigating the discomfort thresholds towards the luminance of light. The aim of this review is to look into how thresholds change in patients with migraine. We performed a PubMed search up to June 2018 targeting all peer-reviewed articles evaluating the changes in threshold, sensory phobia, or sensitivity in patients with migraine. Migraineurs, in general, exhibit lower sensory thresholds compared with healthy controls. These threshold changes seem to follow the different phases during a migraine cycle. In general, thresholds reach a nadir when the headache starts (the ictal phase), rise after the headache ends, and then gradually descend towards the next attack. The sensory modality of measurement – mechanical, thermal, or nociceptive – and the location of measurement –trigeminal vs somatic dermatome – also influence the sensory threshold. Functional imaging studies provide evidence that the hypothalamo-thalamobrainstem network may be the driving force behind the periodic threshold changes. In summary, there is evidence in the literature that migraine could be understood as a periodic sensory dysregulation originating from the brain. Nevertheless, the interstudy discrepancy is still high due to different study designs and a lack of focus on distinct migraine phases. Further well-designed and harmonized studies with an emphasis on the cyclic changes still need to be conducted.

A Multiplexed Microfluidic Platform toward Interrogating Endocrine Function: Simultaneous Sensing of Extracellular Ca2+ and Hormone

Extracellular Ca2+ ([Ca2+]ex) is an important regulator of various physiological and pathological functions, including intercellular communication for synchronized cellular activities (e.g., coordinated hormone secretion from endocrine tissues). Yet it is rarely possible to concurrently quantify the dynamic changes of [Ca2+]ex and related bioactive molecules with high accuracy and temporal resolution. This work aims to develop a multiplexed microfluidic platform to enable monitoring oscillatory [Ca2+]ex and hormone(s) in a biomimetic environment. To this end, a low-affinity fluorescent indicator, Rhod-5N, is identified as a suitable sensor for a range of [Ca2+]ex based on its demonstrated high sensitivity and selectivity to Ca2+ in biomedical samples, including human serum and cell culture medium. A microfluidic chip is devised to allow for the immobilization of microscale subjects (analogous to biological tissues), precise control of the perfusion gradient at sites of interest, and integration of modalities for fluorescence measurement and enzyme-linked immunosorbent assay. As this analytical system is demonstrated to be viable to quantify the dynamic changes of Ca2+ (0.2-2 mM) and insulin (15-150 mU L-1) concurrently, with high temporal resolution, it has the potential to provide key insights into the essential roles of [Ca2+]ex in the secretory function of endocrine tissues and to identify novel therapeutic targets for human diseases.

Smith and Aitkenhead’s Textbook of Anaesthesia, 7th ed

Smith and Aitkenhead’s Textbook of Anaesthesia, 7th ed

Deep Learning-Based Super-resolution Ultrasound Speckle Tracking Velocimetry

Deep ultrasound localization microscopy (deep-ULM) allows sub-wavelength resolution imaging with deep learning. However, the injection of contrast agents (CAs) in deep-ULM is debatable because of their potential risk. In this study, we propose a deep learning-based super-resolution ultrasound (DL-SRU), which employs the concept of deep-ULM and a convolutional neural network. The network is trained with synthetic tracer images to localize positions of red blood cells (RBCs) and reconstruct vessel geometry at high resolution, even for CA-free ultrasound (US) images. The proposed algorithm is validated by comparing the full width at half-maximum values of the vascular profiles reconstructed by other techniques, such as the standard ULM and the US average intensity under in silico and in vitro conditions. RBC localization by DL-SRU is also compared with that by other localization approaches to validate its performance under in vivo condition, especially for veins in the human lower extremity. Furthermore, a two-frame particle tracking velocimetry (PTV) algorithm is applied to DL-SRU localization for accurate flow velocity measurement. The velocity profile obtained by applying the PTV is compared with a theoretical value under in vitro condition to verify its compatibility with the flow measurement modality. The velocity vectors of individual RBCs are obtained to determine the applicability to in vivo conditions. DL-SRU can achieve high-resolution vessel morphology and flow dynamics in vasculature, mapping 110 super-resolved images per second on a standard PC, regardless of various imaging conditions. As a result, the DL-SRU technique is much more robust in localization compared with previous deep-ULM. In addition, the performance of DL-SRU is nearly the same as that of deep-ULM in rapid computational processing and high measurement accuracy. Thus, DL-SRU might become an effective and useful instrument in clinical practice.

Optical coherence tomography versus intravascular ultrasound in patients with myocardial infarction: a diagnostic performance study of pre-percutaneous coronary interventions.

Accurate coronary measurements are important in guiding percutaneous coronary intervention. Intravascular ultrasound is a widely accepted diagnostic modality for coronary measurement before percutaneous coronary intervention. The spatial resolution of optical coherence tomography is 10 times larger than that of intravascular ultrasound. The objective of the study was to compare quantitative and qualitative parameters of frequency domain optical coherence tomography (FDOCT) with those of intravascular ultrasound and coronary angiography in patients with acute myocardial infarction. Diagnostic parameters of coronary angiography, intravascular ultrasound, and FDOCT of 250 patients with coronary artery disease who required admission diagnosis were included in the analyses. Minimum lumen diameter detected by FDOCT was larger than that detected by quantitative coronary angiography (2.11±0.1 vs 1.89±0.09 mm, P<0.0001, q=34.67) but smaller than that detected by intravascular ultrasound (2.11±0.1 vs 2.19±0.11 mm, P<0.0001, q=12.61). Minimum lumen area detected by FDOCT was smaller than that detected by intravascular ultrasound (3.41±0.01 vs 3.69±0.01 mm2, P<0.0001). FDOCT detected higher numbers of thrombus, tissue protrusion, dissection, and incomplete stent apposition than those detected by intravascular ultrasound (P<0.0001 for all). More accurate and sensitive results of the coronary lumen can be detected by FDOCT than coronary angiography and intravascular ultrasound (level of evidence: III).