Detection of small intrahepatic metastases of hepatocellular carcinomas using diffusion-weighted imaging: comparison with conventional dynamic MRI

Purpose

The purpose of our study was to compare diffusion-weighted MR imaging (DWI) with conventional dynamic MRI in terms of the assessment of small intrahepatic metastases from hepatocellular carcinoma (HCC).

Materials and Methods

In 24 patients with multifocal, small (≤2 cm) intrahepatic metastatic foci of advanced HCC, a total of 134 lesions (≤1 cm, n=81; >1 cm, n=53) were subjected to a comparative analysis of hepatic MRI including static and gadopentetate dimeglumine-enhanced dynamic imaging, and DWI using a single-shot spin-echo echo-planar MRI (b values=50, 400 and 800 s/mm²), by two independent reviewers.

Results

A larger number of the lesions were detected and diagnosed as intrahepatic metastases on DWI [Reviewer 1, 121 (90%); Reviewer 2, 117 (87%)] than on dynamic imaging [Reviewer 1, 107 (80%); Reviewer 2, 105 (78%)] (P<.05). For the 81 smaller lesions (≤1 cm), DWI was able to detect more lesions than dynamic imaging [Reviewer 1, 68 (84%) vs. 56 (69%), P=.008; Reviewer 2, 65 (80%) vs. 55 (68%), P=.031], but there was no statistically significant difference between the two image sets for larger (>1 cm) lesions.

Conclusion

Due to its higher detection rate of subcentimeter lesions, DWI could be considered complementary to dynamic MRI in the diagnosis of intrahepatic metastases of HCCs.     

Hypervascular hepatocellular carcinoma in the cirrhotic liver: diffusion-weighted imaging versus superparamagnetic iron oxide-enhanced MRI

Purpose

The purpose of the study was to validate diffusion-weighted imaging (DWI) in the assessment of hypervascular hepatocellular carcinoma (HCC) compared with superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) in the cirrhotic liver.

Material and Methods

Forty-six consecutive patients with 106 hypervascular focal lesions in the cirrhotic liver who underwent DWI using three b factors and gadopentetate dimeglumine-enhanced dynamic MRI followed by SPIO-enhanced MRI were enrolled. Two independent radiologists evaluated two separated image sets (SPIO set, dynamic MRI and SPIO-enhanced T2*-weighted images; DWI set, DWI and dynamic MRI) and assigned confidence levels for diagnosis of HCC using a five-point scale for each lesion. Area under the receiver operating characteristic curve (A_z) was calculated for each image set.

Results

The A_z value of the DWI set was larger than the SPIO set by both readers (reader 1, 0.936 vs. 0.900, P=.050; reader 2, 0.938 vs. 0.905, P=.110). For the sensitivity (reader 1, 93.1% vs. 86.2%, P=.146; reader 2, 95.4% vs. 88.5%, P=.070) and specificity (reader 1, 89.5% vs. 73.7%, P=.250; reader 2, 79.0% vs. 73.7%, P=1.000) of HCC diagnosis, DWI sets were superior to SPIO sets without statistically significant differences.

Conclusion

For assessment of hypervascular HCC, DWI in combination with dynamic MRI provides comparable or slightly better information compared with the combination of dynamic and SPIO-enhanced MRI.     

Heterogeneous catalyst SiO2–LaCl3·7H2O: characterization and microwave-assisted green synthesis of α-aminophosphonates and their antimicrobial activity

Molecular Diversity - Silica-supported lanthanum (III) chloride (SiO2–LaCl3·7H2O) was prepared and characterized by infrared spectroscopy, X-ray diffraction analysis, scanning electron...     

Power Series Rings Satisfying a Zero Divisor Property

In this note we continue to study zero divisors in power series rings and polynomial rings over general noncommutative rings. We first construct Armendariz rings which are not power-serieswise Armendariz, and find various properties of (power-serieswise) Armendariz rings. We show that for a semiprime power-serieswise Armendariz (so reduced) ring R with a.c.c. on annihilator ideals, R[[x]] (the power series ring with an indeterminate x over R) has finitely many minimal prime ideals, say B ₁,…,B _m , such that B ₁… B _m  = 0 and B _i  = A _i [[x]] for some minimal prime ideal A _i of R for all i, where A ₁,…,A _m are all minimal prime ideals of R. We also prove that the power-serieswise Armendarizness is preserved by the polynomial ring extension as the Armendarizness, and construct various types of (power-serieswise) Armendariz rings.     

Selectively strong molecular adsorption on boron nitride monolayer induced by transition metal substrate

We studied adsorption of several molecules (CO, CO₂, H₂O, N₂O, NO, NO₂, and O₂) on hexagonal boron nitride (h-BN) monolayers supported on transition metal (TM) surfaces, using density functional calculations. We observed that all the molecules bind very weakly on the pristine h-BN, with binding energies in the range of 0.02–0.03 eV. Interestingly, however, when h-BN is supported on the TM surface, NO₂ and O₂ become strongly chemisorbed on h-BN, with binding energies of >1 eV, whereas other molecules still physisorbed, with binding energies of ～0.1 eV at most. The electron transfer from TM to p_z states of h-BN played a substantial role in such strong bindings of NO₂ and O₂ on h-BN, as these molecules possess unpaired electrons that can interact with p_z states of h-BN. Such selective molecular binding on h-BN/TM originates from the peculiar distribution of the spin-polarized highest occupied and lowest unoccupied molecular orbitals of NO₂ and O₂. Strong molecular adsorption and high selectivity would make the h-BN/TM system possible for a variety of applications such as catalysts and gas sensors.     

High‐performance In–Zn–O thin‐film transistors with a soluble processed ZrO2 gate insulator

Spin‐coated zirconium oxide films were used as a gate dielectric for low‐voltage, high performance indium zinc oxide (IZO) thin‐film transistors (TFTs). The ZrO₂ films annealed at 400 °C showed a low gate leakage current density of 2 × 10^–8 A/cm² at an electric field of 2 MV/cm. This was attributed to the low impurity content and high crystalline quality. Therefore, the IZO TFTs with a soluble ZrO₂ gate insulator exhibited a high field effect mobility of 23.4 cm²/V s, excellent subthreshold gate swing of 70 mV/decade and a reasonable I_on/off ratio of ～10⁶. These TFTs operated at low voltages (～3.0 V) and showed high drain current drive capability, enabling oxide TFTs with a soluble processed high‐k dielectric for use in backplane electronics for low‐power mobile display applications. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Templated syntheses of Pt thin films with feature sizes of 3, 6 and 9 nm and their effects on SERS

We report on the syntheses of nanostructured Pt films with three different feature sizes of 3, 6 and 9 nm and their effects to the surface enhance Raman spectroscopy of rhodamine 6G (Rh6G) analytes. The syntheses of the Pt films have been achieved through templating the pore structures of mesoporous silica thin films (MSTFs). For the purpose of the present study, we synthesized three MSTFs with pore sizes 3, 6 and 9 nm. Other than the pore sizes, the silica thin films have the same pore structures. The Pt films have been synthesized by depositing Pt into the pores of the template MSTFs and removing the templates after the deposition. The Pt films produce strong Raman spectra of Rh6G with the intensity increasing as the feature size of the Pt film increases. Simulations of the induced electromagnetic fields on the Pt films show the same trend as the observed Raman intensity with the feature size. Copyright © 2012 John Wiley & Sons, Ltd.     

Probing of susceptibility structures through the distant dipolar field effect

In this paper, the utilization of the distant dipolar field (DDF) signal to extract the properties of susceptibility structures over a subvoxel length scale is investigated. Numerical simulations are performed to study a system of randomly distributed blood vessels with a susceptibility offset inside a voxel. It is shown that the DDF signal of the system as a function of the strength of the correlation gradient field manifests a peak that depends on the volume ratio, size, and susceptibility offset of the blood vessels. In particular, the location of the signal peak is found to vary as powers of these parameters. As a result, by varying the strength of the correlation gradient field, the characteristic properties of the blood vessels can be extracted from the peak position of the DDF signal. It is also found that, for a given volume ratio of the blood vessels, a smaller size of the blood vessels can be probed when the susceptibility offset is increased. Nevertheless, it is demonstrated that, owing to the broad width of the signal peak, the DDF effect generally cannot be used for the preferential selection of the signal arising from the blood vessels on the length scale determined by the correlation length.     

Measurements of entrance surface dose using a fiber-optic dosimeter in diagnostic radiology

In this study, a fiber-optic dosimeter (FOD) was developed to measure entrance surface dose (ESD) in diagnostic radiology. We measured the scintillating lights in order to obtain ESDs, which changed with the various exposure parameters of a digital radiography (DR) system, such as tube potential, current-time product, focus-surface distance (FSD), and field size, using the fabricated FOD system. From the experimental results, the output light signals of the FOD were similar to the ESDs of the conventional semiconductor dosimeter. In conclusion, we characterized the measured ESDs as functions of exposure parameters by using two different types of dosimeters and demonstrated that the proposed FOD using a plastic scintillating fiber and a plastic optical fiber (POF) makes it possible to measure ESDs in the energy range of diagnostic radiology. From the results of this study, it is anticipated that the FOD will be a useful dosimeter in low-energy photon applications including diagnostic radiology.     

Measurements of planar and depth dose distributions using a scintillating fiber-optic image sensor system for dosimetry in radiotherapeutic applications

We developed a scintillating fiber-optic image sensor system (SFISS) using square plastic optical fibers (POFs), a scintillating film, a right-angle mirror, and a complementary metal-oxide semiconductor (CMOS) image camera for dosimetry in radiotherapeutic applications. In this study, the scintillating light images were obtained for measuring two-dimensional planar dose distributions of a 6MV photon beam in a solid-water phantom. We also measured the percentage depth doses (PDDs) of 6 and 15MV photon beams using the SFISS and compared them with those obtained using conventional dosimetry films. The proposed sensor has many advantages, such as real-time readout, high-resolution measurement, and lack of corrections for temperature, pressure, and humidity. From the results of this study, it is expected that a SFISS can be developed to accurately measure the dose distribution in a small beam field for stereotactic radiosurgery (SRS).