Ultrasound Measurement of Rectus Femoris Muscle Parameters for Discriminating Sarcopenia in Community-Dwelling Adults

OBJECTIVES

Sarcopenia patients require more medical attention and caretaking. As such, early detection of sarcopenia and appropriate interventions are crucial for decreasing medical costs and meeting the challenges of aging populations. The aim of the present study was to develop a reliable and accurate model to estimate muscle mass using ultrasound-derived parameters from the rectus femoris (RF), referenced by dual-energy X-ray absorptiometry.

METHODS

Cross-sectional study was performed. The study patients were recruited by Taipei Veterans General Hospital (No. 2016-07-013C) between 2016 and 2019. A total of 91 community-dwelling adults (35 men and 56 women) were enrolled in this study. Ultrasound measurements of RF muscle thickness (MT), cross-sectional area (CSA), and muscle volume (MV) were performed in B-mode. Muscle strength and physical performance were also examined. Multivariate linear regression was used to build models for the prediction of appendicular skeletal muscle index (ASMI) based on MT, CSA, and MV values. The accuracy of ultrasound RF measurements for predicting sarcopenia was evaluated by using receiver operating characteristic (ROC) curve analysis.

RESULTS

The regression equations used for ASMI prediction (adjusted body mass index, sex, and leg length) had high precision and low error. Moreover, the MV model results were close to those of the CSA model and higher than those of the MT model. The ROC analysis showed that both MV and CSA had excellent discrimination when assessing sarcopenia (AUC = 0.83 and 0.81, respectively), whereas MT showed acceptable discrimination (AUC = 0.73).

CONCLUSIONS

Ultrasound-derived RF MV was accurate when predicting ASMI and diagnosing sarcopenia in community-dwelling adults.

Intercostal Nerve Block Using an Innovative Intraneedle Ultrasound Transducer: A Proof-of-Concept study

Intercostal nerve block is a widely used and effective approach to providing regional anesthesia in the thoracic region for pain relief. However, during ultrasound-guided intercostal nerve block, inaccurate identification of the anatomic structures or suboptimal positioning of the needle tip may result in complications and blockade failure. In this study, we designed an intraneedle ultrasound (INUS) system and validated its efficacy in identifying anatomic structures relevant to thoracic region anesthesia. The 20-MHz INUS transducer comprised a single lead magnesium niobate-lead titanate crystal, and gain was set to 20 dB. It fit into a regular 18G needle and emitted radiofrequency-mode ultrasound signals at 1 mm from the needle tip. One hundred intercostal punctures were performed in 10 piglets. Intercostal spaces were identified by surface ultrasound or palpation and located by inserting and advancing the INUS transducer needle until the appropriate anatomy was identified. Blockade success was defined by ideal saline and dye spreading and confirmed by dissection. The pleura had a distinctive ultrasound signal, and successful detection of the intercostal muscles, endothoracic fascia and double-layered parietal and visceral pleura was achieved in all 100 puncture attempts. INUS allows real-time identification of intercostal structures and facilitates successful intercostal nerve blocks.

Autofluorescence reveals menstrual phase in the endometrium

OBJECTIVE

Tissue contains fluorophores that autofluoresce without additional dye or photosensitizer with the appropriate light excitation. This technique has been widely applied for discrimination between normal and precancerous tissue. The aim of this study was to explore the capability and reliability of autofluorescence phase determination in samples of human endometrium.

METHODS

A total of 70 measurement sites from 31 endometrial tissue samples from hysterectomy were enrolled. Xenon light (330 nm) was directed at the endometrial tissue and the resultant autofluorescence intensity recorded. Spectra were then grouped according to the proliferative and secretory phase, with multivariant analysis, partial least square (PLS) and analysis of variance (ANOVA) used for evaluation of the statistical significance of phase determination.

RESULTS

Both proliferative and secretory autofluorescence spectra showed a similar characteristic triple-peak curve shape pattern, however, each of the intensities at the three peaks between the two phases varied markedly (p < 0.01). PLS analysis confirmed that collagen, NADH and FAD autofluorescence were the principle determinants of endometrial spectrum; the sensitivity and specificity of phase determination by autofluorescent was 100% and 97%, respectively.

CONCLUSION

Autofluorescence measurement provides real-time information on endometrial phase status and, based on our results, it appears reasonable to suggest that it may be promising as a clinical tool for prompt phase interpretation.

Stepwise logistic regression analysis of tumor contour features for breast ultrasound diagnosis

To assist the ultrasound (US) differential diagnosis of solid breast tumors by using stepwise logistic regression (SLR) analysis of tumor contour features, we retrospectively reviewed 111 medical records of digitized US images of breast pathologies. They were pathologically proved benign breast tumors from 40 patients (i.e., 40 fibroadenomas) and malignant breast tumors from 71 patients (i.e., 71 infiltrative ductal carcinomas). Radiologists, before analysis by the computer-aided diagnosis (CAD) system, segmented the tumors manually. The contour features were calculated by measuring the radial length of tumor boundaries. The features selection process was accomplished using a stepwise analysis procedure. Then, an SLR model with contour features was used to classify tumors as benign or malignant. In this experiment, cases were sampled with "leave-one-out" test methods to evaluate the SLR performance using a receiver operating characteristic (ROC) curve. The accuracy of our SLR model with contour features for classifying malignancies was 91.0% (101 of 111 tumors), the sensitivity was 97.2% (69 of 71), the specificity was 80.0% (32 of 40), the positive predictive value was 89.6% (69 of 77), and the negative predictive value was 94.1% (32 of 34). The CAD system using SLR can differentiate solid breast nodules with relatively high accuracy and its high negative predictive value could potentially help inexperienced operators to avoid misdiagnoses. Because the SLR model is trainable, it could be optimized if a larger set of tumor images were supplied.

A new 3-D display method for 12-lead ECG

A new three-dimensional (3-D) 12-lead electrocardiogram (ECG) display method is presented which employs a 3-D rectangular coordinate system to display the 12-lead cardiac electric signals in two 3-D graphs. The 3-D graph consists of a temporal axis representing the time domain of the cardiac signals, a spatial axis representing the lead positions, and an amplitude axis representing the voltages of the cardiac signals. The six horizontal plane leads and the other six frontal plane leads were displayed in two 3-D graphs, respectively. The voltages of the cardiac signals were represented in rainbow-like colors. Cubic interpolation was employed to insert interconnecting points between neighboring leads on each plane and to smooth the surface of the 3-D ECG graphs. The 3-D ECG graphs of a normal subject, a patient with myocardial infarction, and a patient with left bundle branch block were presented in this paper. This new display method could not only be used as a complementary display method to the 12-lead ECG, but also provide physicians with an overall integral view about the spatial distribution of the cardiac signals.

Autofluorescence spectroscopic differentiation between normal and cancerous colorectal tissues by means of a two-peak ratio algorithm

We conducted an ex vivo study with light-induced autofluorescence spectroscopy to distinguish between normal and cancerous colorectal tissues. A total of 20 normal and 20 cancerous tissue samples were obtained from 20 patients undergoing oncologic surgery of the colon and rectum. The tissue diagnosis was confirmed histologically. After excitation, the autofluorescence spectra of each sample were measured and recorded. To determine the most appropriate excitation wavelength, we analyzed the autofluorescence spectra at excitation wavelengths of 280 to 400 nm, in 10-nm increments. To distinguish between normal and cancerous tissues, we first calculated the "two-peak ratio" (the ratio of the integrated intensity of the first peak +/- 6 nm to the integrated intensity of the second peak +/- 6 nm) of the autofluorescence spectra. By applying receiver operating characteristic (ROC) curves and calculating the areas under the ROC curves (AUC), we found 330 and 340 nm to be the most appropriate excitation wavelengths to distinguish between cancerous and normal colorectal tissue. When approximate thresholds were selected, autofluorescence spectroscopy with 330 nm excitation yielded a sensitivity of 85%, a specificity of 90%, and a positive predictive value of 89% for detection of cancerous tissue. The ex vivo autofluorescence study and two-peak ratio algorithm developed herein may be very useful for developing an algorithm for in vivo diagnosis of colorectal cancer.

Implementation of spectral width Doppler in pulsatile flow measurements

In this paper, we present an automatic beam-vector (Doppler) angle and flow velocity measurement method and implement it in pulsatile flow measurements using a clinical Doppler ultrasound system. In current clinical Doppler ultrasound flow velocity measurements, the axis of the blood vessel needs to be set manually on the B-scan image to enable the estimation of the beam-vector angle and the beam-vector angle corrected flow velocity (the actual flow velocity). In this study, an annular array transducer was used to generate a conical-shaped and symmetrically focused ultrasound beam to measure the flow velocity vectors parallel and perpendicular to the ultrasound beam axis. The beam-vector angle and flow velocity is calculated from the mode frequency (f(d)) and the maximum Doppler frequency (f(max)) of the Doppler spectrum. We develop a spectrum normalization algorithm to enable the Doppler spectrum averaging using the spectra obtained within a single cardiac cycle. The Doppler spectrum averaging process reduces the noise level in the Doppler spectrum and also enables the calculation of the beam-vector angle and flow velocity for pulsatile flows to be measured. We have verified the measurement method in vivo over a wide range of angles, from 52 degrees to 80 degrees, and the standard deviations of the measured beam-vector angles and flow velocities in the carotid artery are lower than 2.2 degrees and 12 cm/s (about 13.3%), respectively.

A probability-based multivariate statistical algorithm for autofluorescence spectroscopic identification of oral carcinogenesis

A probability-based multivariate statistical algorithm combining partial least-squares (PLS) and logistic regression was developed to identify the development stages of oral cancer through analysis of autofluorescence spectra of oral tissues. Tissues were taken from a 7,12-dimethylbenz[a]anthracene-induced hamster buccal pouch carcinogenesis model. Analyses were conducted at various excitation wavelengths, ranging from 280 nm to 400 nm in 20 nm increments, to assess classification performance at different excitations. For each excitation the PLS analysis and logistic regression were combined, on the basis of cross validation, to calculate the posterior probabilities of samples belonging to four stages of cancer development: normal tissues, hyperplasia, dysplasia and early cancers and frankly invasive cancers. Results showed that the 320 nm excitation wavelength optimally classified the cancer development stages: the accuracy rates for identifying samples at that excitation were 91.7%, 83.3%, 66.7% and 83.3% for the four respective stages. The average accuracy rate was 81.3%. These results suggest that the algorithm described in this study might be useful for the detection of human oral cancers.

Diagnosis of oral cancer by light-induced autofluorescence spectroscopy using double excitation wavelengths

A cancer diagnostic algorithm, light-induced autofluorescence spectroscopy using double excitations wavelengths, was employed for distinguishing between cancerous and normal oral mucosa. For emission spectra at the shorter excitation wavelengths (280, 290, and 300 nm), the ratio between the area under 325-335 nm and the area under 465-475 nm was calculated. In the same way, for emission spectra at the longer excitation wavelengths (320, 330, and 340 nm), the ratio between the area under 375-385 nm and the area under 465-475 nm was calculated. Receiver operating characteristic curves were used to evaluate the performance of algorithms using single and the double (by combining shorter and longer) excitation wavelengths. The results showed that better performance, up to sensitivity 81.25%, specificity 93.75%, and positive predictive value 92.86%, could be achieved by using the double excitation wavelengths. The present study can be useful as a basis for further investigation on in vivo autofluorescence measurement and analysis using double excitation wavelength.

Doppler angle and flow velocity estimations using the classic and transverse Doppler effects

Current clinical Doppler ultrasound systems could only measure the flow vector parallel to the ultrasound beam axis, and the knowledge of the Doppler angle (beam-to-flow angle) is needed to calculate the real flow velocity. Currently, the Doppler angle is determined visually by manually aligning a vessel axis marker along the blood vessel on the duplex scan image of the ultrasound. The application of this procedure is often limited by practical constraints; therefore, measurements are not reliable. In order to overcome this problem, the authors developed a simple Doppler angle and flow velocity estimation method using a combination of the classic and transverse Doppler effects. This method uses only a single focused annular array transducer to estimate the Doppler angle and the flow velocity. The authors have verified experimentally that this method is successful for measuring constant flow in a flow phantom between 45 degrees and 80 degrees Doppler angle. The standard deviation of the estimated Doppler angles is less than 4.5 degrees . This method could be implemented easily in medical Doppler ultrasound systems to automatically estimate the Doppler angle and the flow velocity.

Autofluorescence in normal and malignant human oral tissues and in DMBA-induced hamster buccal pouch carcinogenesis

Light-induced fluorescence spectroscopy was conducted on human oral malignant and normal tissues. Under 330-nm excitation wavelength, significant differences in fluorescence intensity were observed around 380- and 460-nm emission. Furthermore, 7,12-dimethylbenz[a]anthracene (DMBA)-induced carcinogenesis in hamster buccal pouch was investigated to elucidate whether similar alterations of fluorescence spectroscopy occurred during the development of squamous cell carcinoma. Similar to the spectral profiles of human oral malignant and normal tissues, the most intense fluorescence peaks in the pouches occurred at 380 nm and 460 nm emission under 330 nm excitation wavelength. At 380 nm emission, the fluorescence intensity of normal pouch mucosa was stronger than those of DMBA-treated abnormal tissues at different stages of carcinogenesis. However, at 460 nm emission, the fluorescence intensity of DMBA-treated tissues was not only stronger than that of normal pouch mucosa but also shifted to 470 nm. These results suggest that under 330 nm excitation wavelength fluorescence spectroscopy may be useful for the detection of oral malignant lesions.

New system for long-term monitoring of sperm motility: EDTA effect on semen

Many drugs act as sperm stimulants and are of clinical value for male infertility. Current research deals with the physiological mechanisms of sperm motility/sperm stimulation and how long the effect lasts. For such a study, long-term monitoring of sperm motility becomes essential for traditional semen evaluation. A new system was designed to deal with the microscopic images of semen. Its performance was evaluated by studying the effect of EDTA on sperm motility. EDTA increased sperm curvilinear velocity (Vcl) and straight-line velocity (Vsl) by 31 and 20%. EDTA also prolonged the duration of motility by 68 and 61%, respectively. However, EDTA had less effect on the linearity of forward progression (Lin). The proposed system can analyze semen and does well at monitoring sperm motility for short term and long term. It may be valuable to test the possible role of sperm stimulation for male infertility and assisted reproduction.