Predicting EEG Responses to Attended Speech via Deep Neural Networks for Speech.

Attending to the speech stream of interest in multi-talker environments can be a challenging task, particularly for listeners with hearing impairment. Research suggests that neural responses assessed with electroencephalography (EEG) are modulated by listener's auditory attention, revealing selective neural tracking (NT) of the attended speech. NT methods mostly rely on hand-engineered acoustic and linguistic speech features to predict the neural response. Only recently, deep neural network (DNN) models without specific linguistic information have been used to extract speech features for NT, demonstrating that speech features in hierarchical DNN layers can predict neural responses throughout the auditory pathway. In this study, we go one step further to investigate the suitability of similar DNN models for speech to predict neural responses to competing speech observed in EEG. We recorded EEG data using a 64-channel acquisition system from 17 listeners with normal hearing instructed to attend to one of two competing talkers. Our data revealed that EEG responses are significantly better predicted by DNN-extracted speech features than by hand-engineered acoustic features. Furthermore, analysis of hierarchical DNN layers showed that early layers yielded the highest predictions. Moreover, we found a significant increase in auditory attention classification accuracies with the use of DNN-extracted speech features over the use of hand-engineered acoustic features. These findings open a new avenue for development of new NT measures to evaluate and further advance hearing technology.

Thermal stability of hierarchical microstructural features in additively manufactured stainless steel.

Additive manufacturing of austenitic stainless steel results in an unconventional hierarchical microstructure. This hierarchical microstructure was investigated in detail in the as-built condition. The hierarchical microstructure consists of elongated austenite grains and melt pool fusion boundaries with a spherical cap morphology at the largest length scale. At a smaller length scale elongated columnar cell structures exist with elemental segregation at the cell walls. The cells were found not to be a misorientation structure in themselves as often noted, but rather groups of cells with a specific orientation, which are collected in 3-5 µm domains. At even smaller length scales, amorphous spherical silicates are found along with a high dislocation density along cell walls. The thermal stability of the unconventional features as melt pool boundaries, elongated austenite grains, cell domains, cell structure, amorphous precipitates was investigated systematically in the temperature range 400-1100 °C. The dislocation network forming the cell boundaries dissolves gradually and remains thermally stable up to about 800 °C. The melt pool boundaries are more thermally stable and dissolve above 900 °C. The elongated austenite grains and crystallographic texture are fully stable within the investigated temperature range. The cell domains appear to be pinned by precipitation as the cellular structure is dissolved and gradually straighten and resemble regular low angle grain boundaries. The amorphous silicates act as heterogeneous nucleation sites for the formation of σ-phase in the temperature range 700-800 °C, while at higher treatment temperatures these silicates are replaced by large, oblong Si-Mn oxides and small, round Mn-Cr oxides.

Barriers to and Facilitators of Using a One Button Tracker and Web-Based Data Analytics Tool for Personal Science: Exploratory Study.

BACKGROUND: Individuals' self-tracking of subjectively experienced phenomena related to health can be challenging, as current options for instrumentation often involve too much effort in the moment or rely on retrospective self-reporting, which is likely to impair accuracy and compliance. OBJECTIVE: This study aims to assess the usability and perceived usefulness of low-effort, in-the-moment self-tracking using simple instrumentation and to establish the amount of support needed when using this approach. METHODS: In this exploratory study, the One Button Tracker-a press-button device that records time stamps and durations of button presses-was used for self-tracking. A total of 13 employees of an academic medical center chose a personal research question and used the One Button Tracker to actively track specific subjectively experienced phenomena for 2 to 4 weeks. To assess usability and usefulness, we combined qualitative data from semistructured interviews with quantitative results from the System Usability Scale. RESULTS: In total, 29 barriers and 15 facilitators for using the One Button Tracker were found. Ease of use was the most frequently mentioned facilitator. The One Button Tracker's usability received a median System Usability Scale score of 75.0 (IQR 42.50), which is considered as good usability. Participants experienced effects such as an increased awareness of the tracked phenomenon, a confirmation of personal knowledge, a gain of insight, and behavior change. Support and guidance during all stages of the self-tracking process were judged as valuable. CONCLUSIONS: The low-effort, in-the-moment self-tracking of subjectively experienced phenomena has been shown to support personal knowledge gain and health behavior change for people with an interest in health promotion. After addressing barriers and formally validating the collected data, self-tracking devices may well be helpful for additional user types or health questions.

Amplification rationale for hearing aids based on characteristics of the Japanese language.

OBJECTIVE: Hearing aid amplification rationales have typically been developed by using global averages of the long-term average speech spectrum (LTASS) from Western European languages. However, there are few reports on hearing-aid amplification based on acoustic-phonetic characteristics of the Japanese language. This study's objective is to investigate the LTASS for Japanese, and to compare a typical amplification rationale originally developed mainly for Western European languages with an amplification rationale specifically adjusted to the LTASS for Japanese. METHODS: LTASS for two speech materials provided by four Japanese talkers were analyzed using 1/3 octave bandwidth filters. The speech was recorded with different levels of vocal effort, yielding three LTASS for "soft", "moderate" and "loud" speech. From these results, a gain offset of the hearing-aid amplification for Japanese was obtained as compared to ANSI S3.5. Speech intelligibility for an amplification rationale for Western European languages and the newly-developed Japanese version was obtained for presentation levels of 50 dB SPL, 65 dB SPL and 80 dB SPL. Nineteen people with mild to moderate hearing loss participated in the speech intelligibility experiment. Scores in% correct were arcsine-transformed and subjected to repeated measures ANOVA with pairwise comparisons of significant main effects using Bonferroni adjustments for multiple comparisons. RESULTS: The LTASS for Japanese was slightly different from the values of previous reports. A comparison of LTASS values to ANSI S3.5 with values for Japanese showed that the Japanese amplification rationale for "moderate" speech levels required more gain in the low-frequency area, and less gain in the high-frequency area. There was no significant difference in the speech intelligibility level between the amplification characteristics of Western European languages and Japanese language at each presentation level. CONCLUSION: It was shown that for hearing-aid amplification for Japanese, adjustments based on LTASS differences for Western European Languages could be made. This preserved speech intelligibility at the same level as the original amplification rationale, suggesting that there was no need to consider differences in phonetics of Japanese to optimize speech understanding.

Insights into the composition of ancient Egyptian red and black inks on papyri achieved by synchrotron-based microanalyses.

A hitherto unknown composition is highlighted in the red and black inks preserved on ancient Egyptian papyri from the Roman period (circa 100 to 200 CE). Synchrotron-based macro-X-ray fluorescence (XRF) mapping brings to light the presence of iron (Fe) and lead (Pb) compounds in the majority of the red inks inscribed on 12 papyrus fragments from the Tebtunis temple library. The iron-based compounds in the inks can be assigned to ocher, notably due to the colocalization of Fe with aluminum, and the detection of hematite (Fe2O3) by micro-X-ray diffraction. Using the same techniques together with micro-Fourier transform infrared spectroscopy, Pb is shown to be associated with fatty acid phosphate, sulfate, chloride, and carboxylate ions. Moreover, micro-XRF maps reveal a peculiar distribution and colocalization of Pb, phosphorus (P), and sulfur (S), which are present at the micrometric scale resembling diffused "coffee rings" surrounding the ocher particles imbedded in the red letters, and at the submicrometric scale concentrated in the papyrus cell walls. A similar Pb, P, and S composition was found in three black inks, suggesting that the same lead components were employed in the manufacture of carbon-based inks. Bearing in mind that pigments such as red lead (Pb3O4) and lead white (hydrocerussite [Pb3(CO3)2(OH)2] and/or cerussite [PbCO3]) were not detected, the results presented here suggest that the lead compound in the ink was used as a drier rather than as a pigment. Accordingly, the study calls for a reassessment of the composition of lead-based components in ancient Mediterranean pigments.

Mobile X-ray outside the hospital: a scoping review.

BACKGROUND: For several years mobile X-ray equipment has been routinely used for imaging in patients too unwell within the hospital, when transportation to the radiology department was inadvisable. Now, mobile X-ray examinations are also used outside the hospital. The literature describes that fragile patients may benefit from mobile X-ray, but we need to provide insights into the breadth, depth and gaps in a body of literature. METHODS: The scoping review was performed by searching PubMed, Cinahl, Embase, EconLit and Health Technology Assessment. English-, Danish-, Norwegian-, German-, Italian-, French- and Swedish-language studies, published 1.1.2009-1.5.2020 about mobile X-ray outside the hospital were included. Participants were patients examined using mobile X-ray as the intervention. PRISMA was used when eligible to build up the review. To extract data from the selected articles, we used a structured summary table. RESULTS: We included 12 studies in this scoping review. The results were divided into four topics:1. Target population 2. Population health 3. Experience of care and 4. Cost effectiveness. The main findings are that target population could be larger for instance including hospice patients for palliative care, group dwelling for people with intellectual disabilities, or psychiatric patients, population health may be improved, image quality seems to be good and mobile X-ray may be cost effective. Limitations of language, databases and grey literature may have resulted in studies being missed. CONCLUSIONS: Mobile X-ray may be used outside hospital. There seems to be potential benefits to both patients and health care staff. Based on the published studies it is not possible to draw a final conclusion if mobile X-ray examination is a relevant diagnostic offer and for whom. Further studies are needed to assess the feasibility of use in fragile patients, also regarding staff, relatives and societal consequences and therefore the topic mobile X-ray needs more research.

Mobile X-ray Outside the Hospital vs. X-ray at the Hospital Challenges Exposed in an Explorative RCT Study.

BACKGROUND: For frail patients, it may sometimes be preferable to carry out X-ray examinations at the patients' own home. The general state of such patients may worsen due to transport and change of environment when transported for examination at the hospital. OBJECTIVE: The aim of the randomized controlled trial (RCT) was to investigate if mobile X-ray improves healthcare for fragile patients. The primary outcome was the number of hospitalizations. DATA SOURCES: We collected all data using questionnaires and data from the Electronic Patient Record (ER). PARTICIPANTS: Patients referred to a mobile X-ray examination living in nursing homes and homes for the elderly in the Aarhus Municipality (Denmark). INTERVENTION: mobile X-ray examinations compared to those at the hospital. Study appraisal: Data were collected and stored using the computer programme Redcap. Stata was used for statistical calculations. One hundred and thirty-six patients were included in the RCT. We did not find significant differences between mobile X-ray (intervention) and X-ray at the hospital (control) concerning hospitalizations and number of hospital days. Challenges: We met several challenges when carrying out RCT in the planned study population. Doctors often withdraw the referral when they found out that their patient should go to the hospital instead of mobile X-ray. The nursing home staff often considered the patient too frail to allow the test person to ask questions post X-ray. We also met challenges in the randomization method resulting in bias in the first data collection, so we had to adjust the randomization method. CONCLUSIONS: For the fragile patients in the present explorative study, mobile X-ray did not significantly reduce the number of hospitalizations compared to X-ray at the hospital. Yet, mobile X-ray may be a new important diagnostic tool for more precise treatment to the frailest patients for whom transportation to the hospital is too exhausting. We need studies with focus on this aspect. We also recommend future RCT studies in a population for which mobile X-ray has not yet been a possibility.

The perceptual flow of phonetic information.

Over a long and distinguished career, Randy Diehl has elucidated the brain mechanisms underlying spoken language processing. The present study touches on two of Randy's central interests, phonetic features and Bayesian statistics. How does the brain go from sound to meaning? Traditional approaches to the study of speech intelligibility and word recognition are unlikely to provide a definitive answer. A finer-grained, Bayesian-inspired approach may help. In this study, listeners identified 11 Danish consonants spoken in a Consonant + Vowel + [l] environment. Each syllable was filtered so that only a portion of the original audio spectrum was presented. Three-quarter-octave bands of speech, centered at 750, 1,500, and 3,000 Hz, were presented individually and in combination. The conditional, posterior probabilities associated with decoding the phonetic-features Voicing, Manner, and Place of Articulation were computed from confusion matrices to delineate the perceptual flow of phonetic information processing. Analysis of the conditional probabilities associated with both correct and incorrect feature decoding suggest that Manner of articulation is linked to the decoding of Voicing (but not vice-versa), and that decoding of Place of articulation is associated with decoding of Manner of articulation (but not the converse). Such feature-decoding asymmetries may reflect processing strategies in which the decoding of lower-level features, such as Voicing and Manner, is leveraged to enhance the recognition of more complex linguistic elements (e.g., phonetic segments, syllables, and words), especially in adverse listening conditions. Such asymmetric feature decoding patterns are consistent with a hierarchical, perceptual flow model of phonetic processing.

The effects of a single session of spinal manipulation on strength and cortical drive in athletes.

PURPOSE: The primary purpose of this study was to investigate whether a single session of spinal manipulation (SM) increases strength and cortical drive in the lower limb (soleus muscle) of elite Taekwondo athletes. METHODS: Soleus-evoked V-waves, H-reflex and maximum voluntary contraction (MVC) of the plantar flexors were recorded from 11 elite Taekwondo athletes using a randomized controlled crossover design. Interventions were either SM or passive movement control. Outcomes were assessed at pre-intervention and at three post-intervention time periods (immediate post, post 30 min and post 60 min). A multifactorial repeated measures ANOVA was conducted to assess within and between group differences. Time and session were used as factors. A post hoc analysis was carried out, when an interactive effect was present. Significance was set at p ≤ 0.05. RESULTS: SM increased MVC force [F(3,30) = 5.95, p < 0.01], and V-waves [F(3,30) = 4.25, p = 0.01] over time compared to the control intervention. Between group differences were significant for all time periods (p < 0.05) except for the post60 force measurements (p = 0.07). CONCLUSION: A single session of SM increased muscle strength and corticospinal excitability to ankle plantar flexor muscles in elite Taekwondo athletes. The increased MVC force lasted for 30 min and the corticospinal excitability increase persisted for at least 60 min.

The nature of ancient Egyptian copper-containing carbon inks is revealed by synchrotron radiation based X-ray microscopy.

For the first time it is shown that carbon black inks on ancient Egyptian papyri from different time periods and geographical regions contain copper. The inks have been investigated using synchrotron-based micro X-ray fluorescence (XRF) and micro X-ray absorption near-edge structure spectroscopy (XANES) at the European Synchrotron Radiation Facility (ESRF). The composition of the copper-containing carbon inks showed no significant differences that could be related to time periods or the geographical locations. This renders it probable that the same technology for ink production was used throughout Egypt for a period spanning at least 300 years. It is argued that the black pigment material (soot) for these inks was obtained as by-products of technical metallurgy. The copper (Cu) can be correlated with the following three main components: cuprite (Cu2O), azurite (Cu3[CO3]2[OH]2) and malachite (Cu2CO3[OH]2).

3-D Vector Flow Estimation With Row-Column-Addressed Arrays.

Simulation and experimental results from 3-D vector flow estimations for a 62 + 62 2-D row-column (RC) array with integrated apodization are presented. A method for implementing a 3-D transverse oscillation (TO) velocity estimator on a 3-MHz RC array is developed and validated. First, a parametric simulation study is conducted, where flow direction, ensemble length, number of pulse cycles, steering angles, transmit/receive apodization, and TO apodization profiles and spacing are varied, to find the optimal parameter configuration. The performance of the estimator is evaluated with respect to relative mean bias ~B and mean standard deviation ~σ . Second, the optimal parameter configuration is implemented on the prototype RC probe connected to the experimental ultrasound scanner SARUS. Results from measurements conducted in a flow-rig system containing a constant laminar flow and a straight-vessel phantom with a pulsating flow are presented. Both an M-mode and a steered transmit sequence are applied. The 3-D vector flow is estimated in the flow rig for four representative flow directions. In the setup with 90° beam-to-flow angle, the relative mean bias across the entire velocity profile is (-4.7, -0.9, 0.4)% with a relative standard deviation of (8.7, 5.1, 0.8)% for ( vx, vy, vz ). The estimated peak velocity is 48.5 ± 3 cm/s giving a -3% bias. The out-of-plane velocity component perpendicular to the cross section is used to estimate volumetric flow rates in the flow rig at a 90° beam-to-flow angle. The estimated mean flow rate in this setup is 91.2 ± 3.1 L/h corresponding to a bias of -11.1%. In a pulsating flow setup, flow rate measured during five cycles is 2.3 ± 0.1 mL/stroke giving a negative 9.7% bias. It is concluded that accurate 3-D vector flow estimation can be obtained using a 2-D RC-addressed array.

Electrostatic and Small-Signal Analysis of CMUTs With Circular and Square Anisotropic Plates.

Traditionally, capacitive micromachined ultrasonic transducers (CMUTs) are modeled using the isotropic plate equation, and this leads to deviations between analytical calculations and finite element modeling (FEM). In this paper, the deflection is calculated for both circular and square plates using the full anisotropic plate equation. It is shown that the anisotropic calculations match excellently with FEM, whereas an isotropic approach causes up to 10% deviations in deflection. For circular plates, an exact solution can be found. For square plates using the Galerkin method, and utilizing the symmetry of the silicon crystal, a compact and accurate expression for the deflection can be obtained. The deviation from FEM in center deflection is <0.1%. The theory of multilayer plates is also applied to the CMUT. The deflection of a square plate was measured on fabricated CMUTs using a white light interferometer. Fitting the plate parameter for the anisotropic calculated deflection to the measurement, a deviation of 0.07% is seen. Electrostatic and small-signal dynamic analysis are performed using energy considerations including anisotropy. The stable position, effective spring constant, pullin distance, and pull-in voltage are found for both circular and square anisotropic plates, and the pressure dependence is included by comparison with the corresponding analysis for a parallel plate. Measurements on fabricated devices with both circular and square plates subjected to increasing bias voltage are performed, and it is observed that the models including anisotropic effects are within the uncertainty interval of the measurements. Finally, a lumped element small-signal model for both circular and square anisotropic plates is derived to describe the dynamics of the CMUT.

Acoustical cross-talk in row-column addressed 2-D transducer arrays for ultrasound imaging.

The acoustical cross-talk in row-column addressed 2-D transducer arrays for volumetric ultrasound imaging is investigated. Experimental results from a 2.7 MHz, λ/2-pitch capacitive micromachined ultrasonic transducer (CMUT) array with 62 rows and 62 columns are presented and analyzed in the frequency-wavenumber domain. The sources of cross-talk are identified and predicted theoretically. The nearest neighbor cross-talk is -23.9±3.7 dB when the array is used as a 1-D array with the rows functioning as both transmitters and receivers. In the row-column configuration, with the columns transmitting and the rows receiving, the cross-talk is reduced to -40.2±3.5 dB.

3-D imaging using row-column-addressed arrays with integrated apodization - part i: apodization design and line element beamforming.

This paper investigates the effect of transducerintegrated apodization in row-column-addressed arrays and presents a beamforming approach specific for such arrays. Row-column addressing 2-D arrays greatly reduces the number of active channels needed to acquire a 3-D volume. A disadvantage of row-column-addressed arrays is an apparent ghost effect in the point spread function caused by edge waves. This paper investigates the origin of the edge waves and the effect of introducing an integrated apodization to reduce the ghost echoes. The performance of a λ/2-pitch 5-MHz 128 + 128 row-column-addressed array with different apodizations is simulated. A Hann apodization is shown to decrease imaging performance away from the center axis of the array because of a decrease in main lobe amplitude. Instead, a static roll-off apodization region located at the ends of the line elements is proposed. In simulations, the peak ghost echo intensity of a scatterer at (x,y, z) = (8, 3, 30) mm was decreased by 43 dB by integrating roll-off apodization into the array. The main lobe was unaffected by the apodization. Simulations of a 3-mm-diameter anechoic blood vessel at 30 mm depth showed that applying the transducer-integrated apodization increased the apparent diameter of the vessel from 2.0 mm to 2.4 mm, corresponding to an increase from 67% to 80% of the true vessel diameter. The line element beamforming approach is shown to be essential for achieving correct time-of-flight calculations, and hence avoid geometrical distortions. In Part II of this work, experimental results from a capacitive micromachined ultrasonic transducer with integrated roll-off apodization are given to validate the effect of integrating apodization into the line elements.

3-D imaging using row-column-addressed arrays with integrated apodization- part ii: transducer fabrication and experimental results.

This paper demonstrates the fabrication, characterization, and experimental imaging results of a 62+62 element λ/2-pitch row-column-addressed capacitive micromachined ultrasonic transducer (CMUT) array with integrated apodization. A new fabrication process was used to manufacture a 26.3 mm by 26.3 mm array using five lithography steps. The array includes an integrated apodization, presented in detail in Part I of this paper, which is designed to reduce the amplitude of the ghost echoes that are otherwise prominent for row-column-addressed arrays. Custom front-end electronics were produced with the capability of transmitting and receiving on all elements, and the option of disabling the integrated apodization. The center frequency and -6-dB fractional bandwidth of the array elements were 2.77 ± 0.26 MHz and 102 ± 10%, respectively. The surface transmit pressure at 2.5 MHz was 590 ± 73 kPa, and the sensitivity was 0.299 ± 0.090 V/Pa. The nearest neighbor crosstalk level was -23.9 ± 3.7 dB, while the transmit-to-receive-elements crosstalk level was -40.2 ± 3.5 dB. Imaging of a 0.3-mm-diameter steel wire using synthetic transmit focusing with 62 single-element emissions demonstrated axial and lateral FWHMs of 0.71 mm and 1.79 mm (f-number: 1.4), respectively, compared with simulated axial and lateral FWHMs of 0.69 mm and 1.76 mm. The dominant ghost echo was reduced by 15.8 dB in measurements using the integrated apodization compared with the disabled configuration. The effect was reproduced in simulations, showing a ghost echo reduction of 18.9 dB.

Modal radiation patterns of baffled circular plates and membranes.

The far field velocity potential and radiation pattern of baffled circular plates and membranes are found analytically using the full set of modal velocity profiles derived from the corresponding equation of motion. The derivation is valid for a plate or membrane subjected to an external excitation force, which is used as a sound receiver in any medium or as a sound transmitter in a gaseous medium. A general, concise expression is given for the radiation pattern of any mode of the membrane and the plate with arbitrary boundary conditions. Specific solutions are given for the four special cases of a plate with clamped, simply supported, and free edge boundary conditions as well as for the membrane. For all non-axisymmetric modes, the velocity potential along the axis of the radiator is found to be strictly zero. In the long wavelength limit, the radiation pattern of all axisymmetric modes approaches that of a monopole, while the non-axisymmetric modes exhibit multipole behavior. Numerical results are also given, demonstrating the implications of having non-axisymmetric excitation using both a point excitation with varying eccentricity and a homogeneous excitation acting on half of the circular radiator.

Ion channel recordings on an injection-molded polymer chip.

In this paper, we demonstrate recordings of the ion channel activity across the cell membrane in a biological cell by employing the so-called patch clamping technique on an injection-molded polymer microfluidic device. The findings will allow direct recordings of ion channel activity to be made using the cheapest materials and production platform to date and with the potential for very high throughput. The employment of cornered apertures for cell capture allowed the fabrication of devices without through holes and via a scheme comprising master origination by dry etching in a silicon substrate, electroplating in nickel and injection molding of the final part. The most critical device parameters were identified as the length of the patching capillary and the very low surface roughness on the inside of the capillary. The cross-sectional shape of the orifice was found to be less critical, as both rectangular and semicircular profiles seemed to have almost the same ability to form tight seals with cells with negligible leak currents. The devices were functionally tested using human embryonic kidney cells expressing voltage-gated sodium channels (Nav1.7) and benchmarked against a commercial state-of-the-art system for automated ion channel recordings. These experiments considered current-voltage (IV) relationships for activation and inactivation of the Nav1.7 channels and their sensitivity to a local anesthetic, lidocaine. Both IVs and lidocaine dose-response curves obtained from the injection-molded polymer device were in good agreement with data obtained from the commercial system.

Parenthetically speaking: classifying the contents of parentheses for text mining.

The contents of parentheses in biomedical text have many potential uses in text mining applications. However, making use of them requires the ability to determine what class of contents they are. A system that automatically classifies parenthesized text into one of 20 categories is presented and evaluated here. It performs at a micro-averaged accuracy of 68% and a macro-averaged accuracy of 60% on an annotated corpus. The application is available as a Java class and as a Perl module.

Can contrast-enhanced ultrasonography replace multidetector-computed tomography in the detection of liver metastases from colorectal cancer?

PURPOSE: To compare the sensitivity and specificity of contrast-enhanced ultrasonography (CEUS) and 4-slice multidetector-computed tomography (MDCT) in the detection of liver metastases in patients with colorectal cancer (CRC). MATERIALS AND METHODS: Candidates for this prospective study were 461 consecutive patients referred to the Department of Colorectal Surgery, Aarhus University Hospital with primary or local recurrence of CRC. The patients underwent liver ultrasonography (US), CEUS, MDCT and intraoperative ultrasonography (IOUS). Fine-needle biopsy was performed on all suspicious lesions. The examinations were interpreted blindly and the combination of US, CEUS, biphasic MDCT, IOUS, follow up and biopsy was the gold standard. RESULTS: Three hundred and sixty-five patients were included. All patients had undergone preoperative US, CEUS and MDCT and 65.5% had received IOUS. The gold standard found liver metastases in 54 patients (14.8%). Multidetector CT found significantly more metastases than CEUS in 15 (28%) of the patients (p=0.02). In a patient-by-patient analysis MDCT had a non-significantly higher sensitivity in the detection of liver metastases compared to CEUS (0.89 versus 0.80, p=0.06). The specificity of CEUS (0.98) was slightly better than that of MDCT (0.94) (p=0.02). CONCLUSION: Multidetector CT found significant more metastases than CEUS, and MDCT had in patient-by-patient analysis a non-significant better sensitivity (p=0.06) in detecting liver metastases in patients with CRC.

The value of contrast enhanced ultrasonography in detection of liver metastases from colorectal cancer: a prospective double-blinded study.

OBJECTIVE: To compare sensitivity and specificity of contrast enhanced ultrasonography (CEUS) with conventional ultrasonography (US) in detection of liver metastases in patients with colorectal adenocarcinoma (CRC) in a patient-by-patient analysis. MATERIALS AND METHODS: A prospective study of 461 consecutive patients referred to the Department of Colorectal Surgery, Aarhus University Hospital with primary or local recurrence of CRC. In order to detect possible liver metastases all patients underwent liver US, followed by CEUS by another investigator. Multislice CT scanning (MDCT), and intraoperative ultrasonography (IOUS) were then performed. Fine-needle biopsy was performed on all suspicious lesions. Each examination was interpreted blindly and the combination of biphasic MDCT, IOUS, follow up and biopsy was the gold standard. RESULTS: Standard of reference found liver metastases in 54 patients (14.8%). Contrast enhanced ultrasonography improved the sensitivity significantly in detection of liver metastases from 0.69 by US to 0.80 (p=0.031). In 24 patients, CEUS found a higher number of metastases than US (p<0.001). The specificity (0.98) and the positive predictive value (0.86) was the same. CONCLUSION: Contrast enhanced ultrasonography improves sensitivity in detection of liver metastases in patients with CRC and in nearly half of the cases CEUS found a higher number of metastases than US.