Development and external validation of a multiparametric MRI-based radiomics model for preoperative prediction of microsatellite instability status in rectal cancer: a retrospective multicenter study.

OBJECTIVES: To establish and validate a radiomics model based on multiparametric magnetic resonance imaging (MRI), and to predict microsatellite instability (MSI) status in rectal cancer patients. METHODS: A total of 199 patients with pathologically confirmed rectal cancer were included. The MSI status was confirmed by immunohistochemistry (IHC) staining. Clinical factors and laboratory data associated with MSI status were analyzed. The imaging data of 100 patients from one of the hospitals were used as the training set. The remaining 99 patients from the other two hospitals were used as the external validation set. The regions of interest (ROIs) were delineated from T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and contrast-enhanced T1WI (CE-T1WI) sequence to extract the radiomics features. The Tree-based approach was used for feature selection. The models were constructed based on the four single sequences and a combination of the four sequences using the random forest (RF) algorithm. The external validation set was used to verify the generalization ability of each model. The receiver operating characteristic (ROC) curves and the area under the curve (AUC) were plotted to evaluate and compare the predictive performance of each model. RESULTS: In the four single-series models, the CE-T1WI model performed the best. The AUCs of the T1WI, T2WI, DWI, and CE-T1WI prediction models in the training set were 0.74, 0.71, 0.71, and 0.78, respectively, while in the external validation set, the corresponding AUCs were 0.67, 0.66, 0.70, and 0.77. The prediction and generalization performance of the combined model of multi-sequences was comparable to that of the CE-T1WI model and it was better than that of the remaining three single-series models, with AUC values of 0.78 and 0.78 in the training and validation sets, respectively. CONCLUSION: The established radiomics models based on CE-T1WI or multiparametric MRI have similar predictive performance. They have the potential to predict MSI status in rectal cancer patients. KEY POINTS: • A radiomics model for the prediction of MSI status in patients with rectal cancer was established and validated using external validation. • The models based on CE-T1WI or multiparametric MRI have better predictive performance than those based on single unenhanced sequence images. • The radiomics model has the potential to suggest MSI status in rectal cancer patients; however, it is not yet a substitute for histological confirmation.

DNA/HSA interaction and nuclease activity of an iron(III) amphiphilic sulfonated corrole.

The DNA binding of amphiphilic iron(III) 2,17-bis(sulfonato)-5,10,15-tris(pentafluorophenyl)corrole complex (Fe-SC) was studied using spectroscopic methods and viscosity measurements. Its nuclease-like activity was examined by using pBR322 DNA as a target. The interaction of Fe-SC with human serum albumin (HSA) in vitro was also examined using multispectroscopic techniques. Experimental results revealed that Fe-SC binds to ct-DNA via an outside binding mode with a binding constant of 1.25 × 10(4) M(-1). This iron corrole also displays good activity during oxidative DNA cleavage by hydrogen peroxide or tert-butyl hydroperoxide oxidants, and high-valent (oxo)iron(V,VI) corrole intermediates may play an important role in DNA cleavage. Fe-SC exhibits much stronger binding affinity to site II than site I of HSA, indicating a selective binding tendency to HSA site II. The HSA conformational change induced by Fe-SC was confirmed by UV/Vis and CD spectroscopy.

Diagnostic accuracy of coronary CT angiography: comparison of filtered back projection and iterative reconstruction with different strengths.

PURPOSE: To investigate the diagnostic accuracy of coronary computed tomographic (CT) angiography (CCTA) using filtered back projection (FBP) and sinogram-affirmed iterative reconstruction (SAFIRE) of different strength factors with invasive coronary angiography as the reference standard. MATERIALS AND METHODS: Fifty consecutive patients (32 men and 18 women) prospectively underwent electrocardiogram-triggered CCTA on a dual-source CT system. The acquisition window was set depending on the heart rate (HR): HR of less than 60 beats per minute (bpm) at the 70% RR interval, 61 to 80 bpm at 30% to 80% RR interval, and greater than 80 bpm at 30% to 50% RR interval; 100 kV and 359 to 377 mA s for patients with a body mass index of less than 24 kg/m, and 410 to 438 mA s at 120 kV for patients with a body mass index of 24 kg/m or greater. Image data were reconstructed using both FBP and SAFIRE. Sinogram-affirmed iterative reconstruction series were reconstructed using 3 different strength factors. Two blinded observers independently assessed the image quality and image impression of each coronary segment using a 4-point scale (1, non-diagnostic; and 4, excellent). Image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were measured. Filtered back projection and all SAFIRE series were independently evaluated for coronary artery stenosis (>50%), and their diagnostic accuracy was compared with invasive coronary angiography. RESULTS: Statistically significant increases in SNR and CNR were obtained when higher strength factors were used. The highest SNR and CNR were found with the highest SAFIRE strength factor of 5; however, this strength also resulted in a more unfamiliar, "plasticlike" image appearance. Imaging quality scores of FBP and different SAFIRE strengths were 3.37 ± 0.49, 3.41 ± 0.47, 3.52 ± 0.30, and 3.48 ± 0.35, respectively (P < 0.001). The diagnostic accuracies were 92.91%, 93.76%, 95.28%, and 94.94% on per-segment level, respectively (P = 0.993). A tendency toward higher diagnostic performance was observed with SAFIRE strength factor 3 on per-segment analysis, albeit without reaching statistical significance. The effective radiation dose equivalent was 5.7 ± 1.6 mSv. CONCLUSION: Sinogram-affirmed iterative reconstruction provides significant improvements in image noise, SNR, and CNR compared with FBP, which are progressive with increasing SAFIRE strength factors. Sinogram-affirmed iterative reconstruction strength factor 3 or 5 is recommended for use with CCTA.

Importance of the average radius of coal particles on determining the methane diffusion coefficient.

The average radius of coal particles is an estimate of the diffusion path in the particle method for determining the diffusion coefficient. It is currently calculated using the arithmetic mean of coal particle sieved intervals. This calculation, however, ignores the coal particle size distribution, resulting in significant deviations when calculating the gas diffusion coefficient. An appropriate average radius calculation method should consider the particle size distribution and the physical essence of diffusion. To accomplish this, a series of methods for calculating the mean particle diameters and their physical significance were reviewed. Next, coal samples were sieved into three intervals, and gas diffusion tests and laser particle size distribution were conducted. Results show that coal particles are within the sieving interval, ranging from 42.01 to 76.18%. By solving the diffusion coefficients using four mean particle diameters based on particle size distribution and diffusive mass transfer, the difference between the arithmetic mean value and these diameters is up to 89.06%. [Formula: see text] and [Formula: see text] are preferred for the calculation of the average radius since they are compatible with coal particle shape and the physical meaning of diffusive mass transfer.

Prevalence and molecular characterization of Cyclospora cayetanensis, Henan, China.

To determine prevalence of Cyclospora cayetanensis infection in Henan, China, we conducted a study of 11,554 hospital patients. Prevalence was 0.70% (95% confidence interval 0.70% ± 0.15%), with all age groups infected. Most cases were found in the summer. Minor sequence polymorphisms were observed in the 18S rRNA gene of 35 isolates characterized.

Diagnostic performance of 320-detector CT coronary angiography in patients with atrial fibrillation: preliminary results.

OBJECTIVE: To evaluate the feasibility, diagnostic accuracy, and radiation dose of CT coronary angiography (CTCA) in patients with atrial fibrillation (AF) using 320-detector CT. METHODS: Thirty-seven patients with persistent AF and suspected coronary artery disease (CAD) were enrolled. All patients underwent both 320-detector CTCA and conventional coronary angiography (CCA). CT image quality and the presence of significant (≥ 50%) stenosis were evaluated by two radiologists blinded to the results of CCA. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated using CCA as the reference standard. Differences in detection of coronary artery stenosis between 320-detector CTCA and CCA were evaluated with McNemar's test. Patient radiation dose was calculated by multiplying dose length product by conversion coefficient of 0.017. RESULTS: In total 474 evaluated coronary segments, 459 (96.8%) segments were diagnostically evaluable. On per-segment analysis, sensitivity, specificity, PPV and NPV were 90.0% (18 of 20), 99.3% (436 of 439), 85.7% (18 of 21) and 99.5% (436 of 438). No significant difference was found between 320-detector CTCA and CCA on the detection of significant stenosis (P = 1.000). Effective doses of 320-detector CTCA was 13.0 ± 4.7 mSv. CONCLUSION: 320-detector CTCA is feasible and accurate in excluding CAD in patients with AF.

p63 and its isoforms as markers of rat oral mucosa epidermal stem cells in vitro.

Although techniques for purifying epidermal stem cells (ESCs) have been established, enriching a pure population of viable ESCs is still a challenging task. One approach toward enhancing the purity and viability of ESCs involves cell markers. While evidence suggests that p63 plays a role in maintaining the population of ESCs, whether p63 can function as a specific marker for ESCs is unclear. We isolated and cultured oral ESCs and illustrated the expression of p63 and its isoforms in rat oral mucosa tissues and stem cells before and after differentiation. Semi-reverse transcription PCR detected the TA, DeltaN, alpha and beta isoforms when cells were cultured for 2 days, but only TA and gamma were detected after 14 days. We also found that p63 is expressed in basal and suprabasal epithelial layers of rat oral mucosa, but it was implied p63 does not mark stem cells specifically, while the DeltaNp63alpha and DeltaNp63beta isoforms may be specific markers of rat oral mucosa stem cells.

Chemical characteristics and sources of PM1 during the 2016 summer in Hangzhou.

During the 2016 Hangzhou G20 Summit, the chemical composition of submicron particles (PM1) was measured by a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) along with a suite of collocated instruments. The campaign was undertaken between August 5 and September 23, 2016. The impacts of emission controls and meteorological conditions on PM1 chemical composition, diurnal cycles, organic aerosol (OA) source apportionment, size distribution and elemental ratios were characterized in detail. Excluding rainy days, the mean PM1 mass concentration during G20 was 30.3 µg/m3, similar to that observed before G20 (28.6 µg/m3), but much lower than that after G20 (42.7 µg/m3). The aerosol chemistry during the three periods was substantially different. Before G20, high PM1 loading mostly occurred at daytime, with OA accounting for 60.1% of PM1, followed by sulfate (15.6%) and ammonium (9.1%). During G20, the OA fraction decreased from 60.1% to 44.6%, whereas secondary inorganic aerosol (SIA) increased from 31.8% to 49.5%. After G20, SIA dominated high PM1 loading, especially at nighttime. Further analysis showed that the nighttime regional transport might play an unfavorable role in the slight increase of secondary PM1 during G20, while the strict emissions controls were implemented. The OA (O/C = 0.58) during G20 was more aged, 48.7% and 13.7% higher than that before and after G20 respectively. Our study highlighted that the emission controls during G20 were of great success in lowering locally produced aerosol and pollutants, despite of co-existence of nighttime regional transport containing aerosol high in low-volatile organics and sulfate. It was implied that not only are emissions controls on both local and regional scale important, but that the transport of pollutants needs to be sufficiently well accounted for, to ensure the successful implementation of air pollution mitigation campaigns in China.

Low dose 320-row CT for left atrium and pulmonary veins imaging--the feasibility study.

OBJECTIVE: To evaluate the feasibility of low dose target-CTA volume scan for left atrium and pulmonary veins imaging using 320-row CT. METHODS: Forty-two patients (females 12, males 30; mean age 55.2 years; mean body mass index (BMI) 25.7 kg/m(2)) with persistent or intermittent atrial fibrillation before catheter ablation were enrolled in this study. Scan protocol was target-CTA volume scan under prospective ECG-gating. The target of the exposure was only set at 40% of the R-R interval (which was at the left atrium maximal volume). The exposure time was minimal setting (350 ms). Tube voltage 100 kV (BMI ≤ 25 kg/m(2)) or 120 kV (BMI>25 kg/m(2)), tube current 350-420 mA, and field of view of 180 mm × 180 mm-200 mm × 200 mm were used. The scanning range was from the level of the tracheal bifurcation to the diaphragm, and enabled to cover the left atrium and central pulmonary veins (120-140 mm). All of patients were divided into two groups according kV setting (100 kV and 120 kV). The image quality (good, moderate and poor) was evaluated by two reviewers. The CT-attenuation, image noise and contrast to noise ratio (CNR) of left atrium and every pulmonary vein branch were evaluated, respectively. The effective dose (ED) was calculated using a conversion coefficient for the chest 0.017. RESULTS: Of 42 patients, the image quality was good in 26 cases (62%) and moderate in 16 cases (38%). There was no statistical difference in the CT-attenuation and CNR of left atrium and central pulmonary veins between the two groups (P>0.05). The mean ED was 1.90 ± 0.19 mSv (range 1.57-2.25 mSv) in 100 kV group, and 3.83 ± 0.31 mSv (range 3.39-4.54 mSv) in 120 kV group. CONCLUSIONS: The low dose target-CTA volume scan is feasible in pulmonary veins and left atrium imaging using 320-row CT. Slim patients can be scanned at 100 kV setting without loss of image quality.

Assessing the left atrial phasic volume and function with dual-source CT: comparison with 3T MRI.

We wanted to assess the performance of dual-source CT (DSCT) for evaluating the left atrial volume and function and we compared this performance to that of the standard reference technique,cardiac cine MR (CMR). Fifty-one patients who were referred for CT coronary angiography were included in the study. Two were subsequently excluded for having un-analyzable MR images at the onset of left atrial contraction. For the remaining 49 patients, the DSCT data sets and FIESTA (fast imaging employing steady-state acquisition) cines of the vertical long axis covering the left atrium and the short axis covering the left ventricle were obtained on the same day. All the images were analyzed to obtain the maximal left atrial volume (LAVmax), the minimal left atrial volume (LAVmin), the left atrial volume just before left atrium contraction (LAVp), the left atrial reservoir volume (LARV), the left atrial ejection fraction (LAEF), the left atrial passive emptying volume (LAPV), the left atrial active emptying volume(LAAV), the left atrial conduit volume (LACV), the left ventricular end-diastolic volume (LVEDV), the left ventricular end-systolic volume (LVESV) and the left ventricular stroke volume (LVSV) by using 3D semi-segmentation software and Report Card 2.0 software, respectively, for the DSCT and CMR. All the parameters were normalized to the body surface area. Intermodality agreement was tested through linear regression and Bland-Altman analyses.Repeated measurements were performed to determine the interobserver variability. The DSCT measurements resulted in good correlation (r > 0.75) compared with those of CMR. However, DSCT slightly,but insignificantly overestimated the indexed LAVmax, LAVmin, LAVp, LARV, LAPV, LAAV and LACV, as reflected by biases of 1.2, 0.9, 1.1, 0.3, 0.1,0.2 and 0.4 ml/m(2), respectively. The LAEF was minimally, but insignificantly underestimated as reflected by a bias of -0.6% (P = ns). The variability of the DSCT measurements was lower than that of the CMR values. DSCT provides highly reliable and reproducible measurements of the left atrial phasic volume and function in patients who are referred for coronary CT imaging.

Three-dimensional CT angiography for the diagnosis and assessment of arteriovenous malformations in the oral and maxillofacial region.

OBJECTIVE: The purpose of this study was to evaluate the diagnostic performance of three-dimensional computed tomography angiography (3D-CTA) for arteriovenous malformations (AVMs) in the oral and maxillofacial region. MATERIALS AND METHODS: Sixty four-slice spiral CT angiography of oral or maxillofacial region was performed in 8 patients with surgically proven arteriovenous malformations. The morphologic features, size, location, boundary, and feeding and draining vessels of lesions were reviewed. RESULTS: AVMs in 5 patients were located in the soft tissues and 3 were in the mandible. CTA of all cases showed tangles of disorganized vessels with well-defined borders. The feeding and draining vessels were enlarged and tortuous. Four patients had bone involvement. CONCLUSION: Sixty four-slice spiral CTA can accurately demonstrate the morphological characteristics of AVMs.

Low-dose adaptive sequential scan for dual-source CT coronary angiography in patients with high heart rate: comparison with retrospective ECG gating.

PURPOSE: To explore feasibility of dual-source CT (DS-CT) prospective ECG-gated coronary angiography in patients with heart rate (HR) higher than 70beat per minute (bpm), and evaluate image quality and radiation dose with comparison to retrospective ECG-gated spiral scan. MATERIALS AND METHODS: One hundred patients who underwent DS-CT coronary angiography (DS-CTCA) with mean HR higher than 70bpm but below 110bpm were enrolled in the study, 50 were scanned by adaptive sequential scan and another 50 were analyzed by retrospectively gated CT scan. The imaging quality of coronary artery segments in the two groups was evaluated using a four-point grading scale by two independent reviewers. Patient radiation dose was calculated by multiplying dose length product by conversion coefficient of 0.017. RESULTS: There was no significant difference between the two groups for mean HR (p=0.305), HR variability (p=0.103), body mass index (p=0.472), and scan length (p=0.208). There was good agreement for image quality scoring between the two reviewers (Kappa=0.72). Coronary evaluability of adaptive sequential scan was 99.7% (608 of 610 segments), while that of retrospective gated scan was 98.7% (614 of 622 segments), showing similar coronary evaluability (p=0.061). Effective doses of adaptive sequential scan and retrospective gated scan were 5.1±1.6 and 11.8±4.5mSv, respectively (p<0.001), showing that adaptive sequential scan reduced radiation dose by 57% compared with that of retrospective gated scan. CONCLUSIONS: In patients with 70-110bpm HR, DS-CTCA adaptive sequential scan shows similar image quality as retrospective ECG-gated spiral scan with 57% reduction of radiation dose.

Immortalization of ameloblastoma cells via reactivation of telomerase function: Phenotypic and molecular characteristics.

Ameloblastoma (AM) is recognized as a benign tumour but locally invasive with a high risk of recurrence. In vitro model systems for studying AM are limited due to the fact that AM cells grow poorly and begin to senesce early. Japanese researchers have reported the construction of an AM cell line, AM-1, by exposing cells to human papillomavirus 16 (HPV16) but retaining the potential of transformation. In this study, we used a retroviral infection method to over-express the human telomerase reverse transcriptase (hTERT) gene to acquire immortality of hTERT(+)-AM cells. Furthermore, it was revealed both by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot that the pathway of immortalization was loss of p16, not p53 or p21. Also, there was no evidence indicating that the hTERT(+)-AM cells underwent malignant transformation by the nude mouse tumorigenicity assay. Taken together, this hTERT-immortalized cell line may be a potentially valuable and reliable cell model for further study of the invasive properties of AM in vitro.