Relative Observer and Technical Error in the Ultrasonic Monitoring of Thyroid Nodular Growth Using Nodular Volume (VOL), vs. Longest Dimension (LD), vs. the Sum of the 3 Nodular Dimensions (SUM3D)

Though not a reliable indicator of malignancy, ultrasonic monitoring of nodule growth still has a role in the evaluation of nodules, e.g. indicating when a nodule may require biopsy or re-biopsy. Observer and technical limitations, however, limit the precision of ultrasonic determination of simple growth, vs. stability or shrinkage. Ultrasonic parameters used for this purpose all have their own limitations. Monitoring nodule growth by VOL frequently exhibits wide and conflicting swings in apparent size compared to the penultimate size, doubtlessly reflecting measurement limitations. As a growth parameter, LD typically exhibits a smoother time course but does not address growth in the other two dimensions. SUM3D includes changes in all dimensions but, like LD, is not a true measure of nodule mass or volume. This study was to determine the relative error of these three growth parameters and how it relates to their relative efficacy for nodular growth monitoring. The anterior-posterior (AP), left-right (LR) and superior-inferior (SI) dimensions of 34 benign nodules were determined ultrasonographically by four pairs of trained observers. One observer of a pair was regarded as a Time-1 observer and the other as a Time-2 observer, simulating the process for determining growth change over time. All observers measured the same image of each of the 34 nodules but were unaware of the measurements obtained by any other observer. For each image for each pair of observers, the dimensions were used to calculate the VOL, LD and SUM3D and the perceived changes thereof from Time-1 to Time-2. Since only one image for each nodule was distributed, differences between the Time-1 vs Time-2 measurements for each nodule could only reflect observer-based differences. “S”-curves plotting the nominal %-change in a parameter reported by the Time-2 observer compared to that reported by the Time-1 observer (x-axis) were rank-ordered from negative to positive changes (y-axis). The %-change in each parameter due to observer/technical error ranging from the highest over-estimate to the lowest were, in order from Top 10%, Middle 40%, and Bottom 10%, respectively: LD: 19-36%, -4 to 6%, -15 to -42%; SUM3D: 15 to 28%, -4 to 4%, -11 to -43%; VOL: 48 to 105%, -13 to 15%, -33 to -81%. The magnitude of %-change from Time-1 to Time-2 for the VOL parameter were 2 to 3 times greater than that of the LD or SUM3D parameters for the top 10% of values, the middle 40% of values, and the bottom 10% of values. These degrees of difference coincide with the wide variability seen in nodular growth curves [not illustrated here] when nodular VOL (y-axis) is plotted as a function of length of observation (x-axis). This study helps explain why monitoring nodular growth by LD or by the SUM3D usually provides a clearer, less fluctuant illustration of thyroid nodule growth over time than does VOL.

Laboratory experiments of water injection coupled with ultrasonic monitoring reveal wave-induced fluid flow in microporous carbonate rock

<p>Monitoring of fluid movements in the crust is one of the most discussed topics in oil & gas industry as well as in geothermal systems and CO<sub>2</sub> storage, but still remains a challenge. The seismic method is one of the most common ways to detect the fluid migration. However, the use of ultrasonic monitoring at the sample scale in laboratory experiments persists as the most effective way to highlight large scale observations in which the boundary conditions are not well constrained.</p><p>To unravel the fluid effect on P-wave and S-wave velocity, we performed mechanical experiments coupled with ultrasonic monitoring on Obourg chalk from Mons basin (Belgium). Water injection tests under critical loading, imbibition tests and evaporation tests provided a full spectrum of observations of fluid-induced wave alteration in term of propagation time and attenuation.</p><p>The analysis of these experimental results showed that significant velocity dispersion and attenuation developed through variations in water saturation, and that these processes are linked to the presence of patches of water and air in the pore space.</p><p>We used the White’s formulation to model the relaxation effects due to spherical pockets of air homogeneously distributed in a water-saturated medium. In this framework, the pressure induced by the passing wave, produces a fluid flow across the water-air boundary with consequent energy loss.</p><p>This model reproduces both qualitatively and quantitatively the experimental results observed on the water injection tests. Indeed, it is shown that the progressive water saturation or desaturation of this chalk, generates a shift of the critical frequency (from the undrained relaxed towards unrelaxed regimes) which at some point matches the resonance frequency of the piezoelectric transducers used in the experimental setup (0.5 MHz). This phenomenon allowed us to get a continuous recording of the relaxation processes induced by saturation variations.</p><p>The outcomes of this work can significantly improve the actual knowledge on coupled effects of waves and fluids which is a crucial aspect of fluid monitoring in the context of reservoir evaluation and production.</p>

Echolocation of bats (Chiroptera Blumenbach, 1779) as an element of their ecological plasticity

Aim. The aim of this work was to briefly summarize the current understanding of the phenomenon of echolocation in the order of bats (Chiroptera Blumenbach, 1779).Discussion. The paper discusses: the place of bats among other taxonomic groups of animals that have the ability of echolocation; the history of the discovery of "ear vision" in bats by L. Spallanzani in the 18th century; the first scientifically based assumptions regarding the use of ultrasound by bats and the discovery of this phenomenon in the middle of the last century; methods for emitting and receiving ultrasound by various taxonomic groups of bats; physical patterns underlying the propagation of ultrasonic waves; characteristics of the returned echo and algorithms for echolocation in bats; echolocation interactions between insectivorous bats and nocturnal moths and possibilities for ultrasonic monitoring of bat populations.Conclusion. The inclusion of ultrasound monitoring of bat populations in integrated ecological and virological studies could form a new point of growth in systems to ensure biological security at both national and global levels.