Summary We attempted to clarify whether serum levels of a carboxy-terminal fragment of ProGRP, , could serve as a more accurate tumour marker in patients with SCLC than neuron-specific enolase (NSE). and NSE were measured retrospectively in 101 newly diagnosed untreated patients with SCLC, 111 with non-small-cell lung cancer (NSCLC) and 114 patients with non-malignant lung diseases. ProGRP(31-98) and NSE levels were determined using a sandwich enzyme-linked immunosorbent assay. Sensitivity in SCLC patients was 72.3% for ProGRP(31-98) and 62.4% for NSE. Comparing the area under curve (AUC) of 'receiver operator characteristics' of ProGRP(31 -98) with that of NSE, ProGRP(31-98) was the more powerful marker in the diagnosis of SCLC (P=0.0001). Serum levels of were higher in the 40 patients with extensive disease than in the 61 patients with limited disease (P=0.0082). ProGRP(31-98) was significantly higher in patients with pure small-cell carcinoma than in patients with mixed small-cell/large-cell carcinoma (P=0.02). In serial measurement in 16 patients responding to treatment, a high degree of correlation was noted between the decrease in serum ProGRP(31-98) levels and clinical response during the second week after treatment (P=0.0045). These results indicate that the determination of serum ProGRP(31-98) levels plays an important role in the diagnosis and treatment of SCLC patients.
Many methods for the analysis of amplitude envelope statistics have been proposed in recent decades to enable echo signal characterization and realize quantitative diagnosis based on these statistics. In the statistical analysis of ultrasound signals, the spatial resolution of the signal is an important factor. An analysis method that offers higher sensitivity than the current analysis model is required to allow the effective use of recently developed high-resolution ultrasonic diagnostic equipment. In this study, we propose a multi-amplitude envelope statistical model called the double Nakagami probability density function (PDF) model that assumes the physical structure of fatty liver disease under high-frequency ultrasound excitation. Application of the proposed model to actual rat livers demonstrated that it was possible to evaluate fatty liver disease at an early stage with a lower scatterer density than that of a normal liver. However, it is difficult to detect the disease at this stage using existing technology.
Quantitative ultrasound (QUS) methods have been widely used for soft tissue characterization. Spatial resolution (i.e. ultrasound frequency) is an important factor for QUS methods. In a previous study, a double Nakagami (DN) distribution model to echo signals from fatty livers using a 15 MHz transducer was used to permit fine-resolution QUS. This study used a filtering approach to quantify steatosis progression using three QUS parameters obtained by fitting a DN distribution model to experimental envelope data. The filter was designed using QUS parameters obtained from three healthy liver. A strong correlation (r = 0.96, p < 0.001) was found between histologically quantified steatosis percentage and the percentage of the liver having non-healthy liver features. This approach was able to successfully diagnose fatty livers (>20% steatosis percentage) in a dataset of 12 livers ranging from 0% to 90% steatosis.
Although there have been several quantitative ultrasound studies on the methods of estimation of scatterer size and acoustic concentration based on the analysis of RF signals for tissue characterization, some problems, e.g., narrow frequency bandwidths and complex sound fields, have limited the clinical applications of such methods. In this report, two types of ultrasound transducer are investigated for the estimation of the scatterer size and acoustic concentration in two glass bead phantoms of different weight concentrations of 0.25 and 2.50% and those in an excised pig liver. The diameters of the glass beads ranged from 5 to 63 µm with an average of 50 µm. The first transducer is a single element and the other is a linear phased array. A comparison of the estimations obtained using both transducers gives an insight into how these methods could be applied clinically. Results obtained using the two transducers were significantly different. One of the possible explanations is that beamforming could significantly affect the backscatter coefficient estimation, which was not taken into account.
High-frequency ultrasound (HFU, >20 MHz) and quantitative ultrasound (QUS) methods permit a means to understand the relationship between anatomical and acoustic characteristics. In our previous research, we showed that analyzing the acoustic scattering with HFU was an effective method for noninvasive diagnosis. However, the depth of field (DOF) of HFU transducers was limited, which constrains the range of QUS analysis. In this study, we seek to improve the accuracy of HFU, QUS-based parameters on the envelope statistics and frequency-based analysis by using an annular array that allows for an extended DOF. A 20-MHz annular-array transducer with five elements was employed to obtain signals which were beamformed in post-processing. Two kinds of low concentration scattering phantoms were scanned with 30-μm step size. Two QUS analysis techniques were employed: the Nakagami distribution and the reflector method. The results demonstrated that the annular array provides a stable analysis over an extended axial range.
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