Článek se souhrnně zabývá problematikou měření molekulární difúze pomoci magnetické rezonance (MR) a uvádí několik typických aplikací zobrazováni difuzních koeficientů v diagnostice např. mozkové ischemic, změn u pacientů s fenylketonurií nebo roztroušenou sklerózou (RS). Obrazy byly měřeny metodou difuzně váženého spinového echa Echo-planar Imaging (EPI) s následnou korekcí geometrické distorze obrazů a výpočtem ADC map (Apparent Diffusion Coeffici geometrické distorze obrazů a výpočtem ADC map (Apparent Diffusion Coefficient). Anizotropie difúze molekul v bílé mozkové hmotě je ukázána u zdravého mozku a jsou uvedeny také orientační hodnoty ADC ve trech základních směrech. Diagnostika mozkové ischemic měřením difuzně vážených obrazů je dnes již dobře známou metodou, která umožňuje nejen zobrazit tkáňové změny již několik minut po ischemické události, ale také rozlišit stáří ischemic. Výrazné změny • pokles až o 40 % - byly naměřeny u pacientů s fenylketonurií, a to v oblastech typických naopak jednat o typickou demyelinizaci, čemuž nasvědčuje prakticky normální hodnota NAA naměřená v těchto oblastech pomocí MR spektroskopie. Také u pacientů s RS jsme naměřili změny ADC, ale jejich velikost a směr (snížení či zvýšení) byly závislé na velikosti postižených míst a pravděpodobně i na jejich stáří.
The presented paper summarizes the problem of assessment of molecular diffusion by magnetic resonance (MR) and discuss several typical applications of diffusion imaging in the diagnosis e.g. of cerebral ischaemia, changes in patients with phenylketonuria or multiple sclerosis (MS). The images were measured using diffiision weighted (DW) spin echo Echo-planar Imaging (EPI) sequence with subsequent correction of the geometrical distorsion of images and calculation of ADC maps (Apparent Diffusion Coefficient). Anisotr opy of molecule diffusion in the white matter of the brain is demonstrated in a healthy brain, as well as approximate ADC values in three basic directions. The diagnosis of cerebral ischaemia by assessment of DW images is nowadays a well known method which makes it possible not only to visualize tissue changes already several minutes after the ischaemic attack but it can also differen¬ tiate the age of the ischaemia. Marked changes - a decline by as much as 40 % - were found in patients with phenylketonuria in areas typical by prolongation of T2. These changes are obviously associated with changes in the myelinization of white matter, but typical demyelinization is not necessarily involved, as suggested by normal NAA values assessed in these areas by MR spectroscopy. Also in patients with MS changes of ADC were found but their magnitude and direction (increase or decrease) depended on the size of the affected areas and probably on their age.
This paper describes a method for determination of the diffusion coefficient and the solubility of radon in plastics. The method is based on the absorption and desorption of radon in plastics. Firstly, plastic specimens are exposed for controlled time to referent (222)Rn concentrations. After exposure, the activity of the specimens is followed by HPGe gamma spectrometry. Using the mathematical algorithm described in this report and the decrease of activity as a function of time, the diffusion coefficient can be determined. In addition, if the referent (222)Rn concentration during the exposure is known, the solubility of radon can be determined. The algorithm has been experimentally applied for different plastics. The results show that this approach allows the specified quantities to be determined with a rather high accuracy-depending on the quality of the counting equipment, it can be better than 10 %.
- MeSH
- Algorithms MeSH
- Diffusion MeSH
- Humans MeSH
- Mathematics MeSH
- Radiation Monitoring * MeSH
- Plastics analysis MeSH
- Radon analysis chemistry MeSH
- Solubility MeSH
- Spectrometry, Gamma MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Czech Republic MeSH
Radon diffusion coefficient is a material parameter which is usually used in the radon mitigation measures design. There are different approaches used for radon diffusion coefficient measurement and assessment. The International comparison measurement which was jointly organised by National Radiation Protection Institute and Faculty of Civil Engineering CTU Prague in 2009 and 2010 has registered 11 laboratories from all over the world. Three sets of samples of polyethylene damp-proof membranes were sent to these laboratories for measurement. Till today, the organisers received only five sets of results. The results showed a great variability among laboratories involved.
INTRODUCTION: Renal cell carcinoma (RCC) accounts for approximately 3% of adult malignancies and more than 90% of neoplasms arising from the kidney. Uninformative percutaneous kidney biopsies vary from 10 to 23%. As a result, 7.5-33.6% of partial nephrectomies in patients with small renal masses (SRM) are performed on benign renal tumors. The aim of this study was to assess the feasibility of the apparent diffusion coefficient (ADC) of the diffusion-weighted imaging (DWI) of MRI, as RCC imaging biomarker for differentiation of SRM. METHOD: Adult patients (n = 158) with 170 SRM were enrolled into this study. The control group were healthy volunteers with normal clinical and radiologic findings (n = 15). All participants underwent MRI with DWI sequence included. RESULTS: Mean ADC values of solid RCC (1.65 ± 0.38 × 10-3 mm2/s) were lower than healthy renal parenchyma (2.47 ± 0.12 × 10-3 mm2/s, p < 0.05). There was no difference between mean ADC values of ccRCC, pRCC and chRCC (1.82 ± 0.22 × 10-3 vs 1.61 ± 0.07 × 10-3 vs 1.46 ± 0.09 × 10-3 mm2/s, respectively, p = ns). An inverse relationship between mean ADC values and Fuhrman grade of nuclear atypia of solid ccRCCs was observed: grade I-1.92 ± 0.11 × 10-3 mm2/s, grade II-1.84 ± 0.14 × 10-3 mm2/s, grade III-1.79 ± 0.10 × 10-3 mm2/s, grade IV-1.72 ± 0.06 × 10-3 mm2/s. This was significant (p < 0.05) only between tumors of I and IV grades. Significant difference (p < 0.05) between mean ADC values of solid RCCs, benign renal tumors and renal cysts was observed (1.65 ± 0.38 × 10-3 vs 2.23 ± 0.18 × 10-3 vs 3.15 ± 0.51 × 10-3 mm2/s, respectively). In addition, there was a significant difference (p < 0.05) in mean ADC values between benign cysts and cystic RCC (3.36 ± 0.35 × 10-3 vs 2.83 ± 0.21 × 10-3 mm2/s, respectively). CONCLUSION: ADC maps with b values of 0 and 800 s/mm2 can be used as an imaging biomarker, to differentiate benign SRM from malignant SRM. Using ADC value threshold of 1.75 × 10-3 mm2/s allows to differentiate solid RCC from solid benign kidney tumors with 91% sensitivity and 89% specificity; ADC value threshold of 2.96 × 10-3 mm2/s distinguishes cystic RCC from benign renal cysts with 90% sensitivity and 88% specificity. However, the possibility of differentiation between ccRCC histologic subtypes and grades, utilizing ADC values, is limited.
- MeSH
- Kidney Diseases, Cystic diagnosis MeSH
- Diagnosis, Differential MeSH
- Diffusion Magnetic Resonance Imaging methods MeSH
- Adult MeSH
- Carcinoma, Renal Cell * diagnosis pathology surgery MeSH
- Organ Sparing Treatments methods MeSH
- Middle Aged MeSH
- Humans MeSH
- Kidney Neoplasms * diagnosis pathology surgery MeSH
- Nephrectomy methods MeSH
- Reproducibility of Results MeSH
- Aged MeSH
- Sensitivity and Specificity MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
INTRODUCTION: Glioblastoma (GBM) is the most common malignant primary brain tumor, and methods to improve the early detection of disease progression and evaluate treatment response are highly desirable. We therefore explored changes in whole-brain apparent diffusion coefficient (ADC) values with respect to survival (progression-free [PFS], overall [OS]) in a cohort of GBM patients followed at regular intervals until disease progression. METHODS: A total of 43 subjects met inclusion criteria and were analyzed retrospectively. Histogram data were extracted from standardized whole-brain ADC maps including skewness, kurtosis, entropy, median, mode, 15th percentile (p15) and 85th percentile (p85) values, and linear regression slopes (metrics versus time) were fitted. Regression slope directionality (positive/negative) was subjected to univariate Cox regression. The final model was determined by aLASSO on metrics above threshold. RESULTS: Skewness, kurtosis, median, p15 and p85 were all below threshold for both PFS and OS and were analyzed further. Median regression slope directionality best modeled PFS (p = 0.001; HR 3.3; 95% CI 1.6-6.7), while p85 was selected for OS (p = 0.002; HR 0.29; 95% CI 0.13-0.64). CONCLUSIONS: Our data show tantalizing potential in the use of whole-brain ADC measurements in the follow up of GBM patients, specifically serial median ADC values which correlated with PFS, and serial p85 values which correlated with OS. Whole-brain ADC measurements are fast and easy to perform, and free of ROI-placement bias.
- MeSH
- Antineoplastic Agents, Alkylating therapeutic use MeSH
- Chemoradiotherapy mortality MeSH
- Diffusion Magnetic Resonance Imaging methods MeSH
- Glioblastoma mortality pathology therapy MeSH
- Combined Modality Therapy MeSH
- Humans MeSH
- Survival Rate MeSH
- Brain Neoplasms mortality pathology therapy MeSH
- Follow-Up Studies MeSH
- Image Processing, Computer-Assisted methods MeSH
- Prognosis MeSH
- Disease Progression MeSH
- Retrospective Studies MeSH
- Temozolomide therapeutic use MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
This paper describes a new device and a method to determine the radon diffusion coefficient in damp-proof membranes developed in the Czech Republic. The main advantage of the device is that it enables tests to be carried out in all the known measuring modes used throughout Europe. Two recently developed computer programs are presented for the numerical modelling of the time-dependent radon transport through damp-proof membranes. According to this method, the radon diffusion coefficient is derived from the process of fitting the numerical solution to the measured curve of radon concentration in a receiver container. Numerical simulation and measured data are also compared. Reasons for disagreements between different methods and specific configurations of the measuring device are also discussed.
Waterproofing, usually made of bitumen or polymers with various additives, is used to protect buildings mainly against dampness, but also against radon transported from the soil beneath the building. The radon diffusion coefficient is a material property which is considered to be strongly influenced by the inner structure (chemical composition, crystallinity) of a measured sample. We have used this parameter together with measurements of mechanical properties (hardness, tensile strength, elongation at break, etc.) and FTIR spectroscopy has been used in order to describe the changes in material properties induced by long-term degradation. This paper summarizes the results of radon diffusion coefficient measurements of waterproof materials exposed to radon, soil bacteria, high temperature and combinations of these factors. We have discovered changes as high as 83 % have been discovered compared to virgin samples.
- MeSH
- Housing MeSH
- Diffusion MeSH
- Construction Materials analysis MeSH
- Humans MeSH
- Radiation Monitoring * MeSH
- Polymers chemistry MeSH
- Air Pollutants, Radioactive analysis MeSH
- Air Pollution, Radioactive prevention & control MeSH
- Radon analysis MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Accurate prediction of early treatment response to systemic therapy (ST) with tyrosine kinase inhibitors (TKI) in patients with metastatic renal cell carcinoma (mRCC) could help avoid ineffective and expensive treatment with serious side effects. Neither RECIST v.1.1 nor Choi criteria successfully discriminate between patients with mRCC who received ST having a short or long time to progression (TTP). There is no biomarker, which is able to predict early therapeutic response to TKIs application in patients with mRCC. The goal of our study was to investigate the potential of apparent diffusion coefficient (ADC) of diffusion-weighted imaging (DWI) of MRI in prediction of early therapeutic response to ST with pazopanib in patients with mRCC. The retrospective study enrolled 32 adult patients with conventional mRCC who received pazopanib (mean duration-7.5 ± 3.45). The mean duration of follow-up was 11.85 ± 4.34 months. In all patients as baseline examination and 1 month after treatment, 1.5T MRI including DWI sequence was performed followed by ADC measurement of the main renal lesion. For assessment of the therapeutic response, RECIST 1.1 is used. Partial response (PR), stable disease (SD) and progressive disease (PD) were observed in 12 (37.50%), 10 (31.25%) and 10 (31.25%) cases with mean TTP of 10.33 ± 2.06 months (95% confidence interval, CI = 9.05-11.61), 7.40 ± 2.50 months (95% CI = 5.61-9.19) and 4.20 ± 1.99 months (95% CI = 2.78-5.62) accordingly (p < 0.05). There was no difference in change of main lesions' longest size 1 month after ST in patients with PR, SD and PD. Comparison of mean ADC values before and 1 month after systemic treatment showed significant decrease by 19.11 ± 10.64% (95% CI = 12.35-25.87) and by 7.66 ± 6.72% (95% CI = 2.86-12.47) in subgroups with PR and SD, respectively (p < 0.05). There was shorter TTP in patients with mRCC if ADC of the main renal lesion 1 month after the ST increased from the baseline less than 1.73% compared to patients with ADC levels above this threshold: 5.29 ± 3.45 versus 9.50 ± 2.04 months accordingly (p < 0.001). Overall, our findings highlighted the use of ADC as a predictive biomarker for early therapeutic response assessment. Use of ADC will be effective and useful for reliable prediction of responders and non-responders to systemic treatment with pazopanib.
- MeSH
- Diffusion Magnetic Resonance Imaging methods MeSH
- Angiogenesis Inhibitors therapeutic use MeSH
- Kaplan-Meier Estimate MeSH
- Carcinoma, Renal Cell diagnostic imaging drug therapy mortality pathology MeSH
- Kidney diagnostic imaging MeSH
- Middle Aged MeSH
- Humans MeSH
- Kidney Neoplasms diagnostic imaging drug therapy mortality pathology MeSH
- Pyrimidines therapeutic use MeSH
- Retrospective Studies MeSH
- ROC Curve MeSH
- Aged MeSH
- Sulfonamides therapeutic use MeSH
- Treatment Outcome MeSH
- Healthy Volunteers MeSH
- Check Tag
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Clinical Trial MeSH
PURPOSE: Inferior vena cava (IVC) involvement by renal cell carcinoma (RCC) is associated with a higher disease stage and is considered a risk factor for poor prognosis. This study aimed to investigate the role of the apparent diffusion coefficient (ADC) of MRI 3D texture analysis in the differentiation of solid and friable tumour thrombus in patients with RCC. MATERIALS AND METHODS: The study involved 27 patients with RCC with tumour thrombus in the renal vein or IVC, surgically treated with nephrectomy and thrombectomy and in whom preoperatively abdominal MRI including the DWI sequence was conducted. For 3D texture analysis, the ADC map was used, and the first-order radiomic features were calculated from the whole volume of the thrombus. All tumour thrombi were histologically classified as solid or friable. RESULTS: The solid and friable thrombus was detected in 51.9 % and 48.1 % of patients, respectively. No differences in mean values of range, 90th percentile, interquartile range, kurtosis, uniformity and variance were found between groups. Equal sensitivity and specificity (93 % and 69 %, respectively) of ADC mean, median and entropy in differentiation between solid and friable tumour thrombus, with the highest AUC for entropy (0.808), were observed. Applying the skewness threshold value of 0.09 allowed us to achieve a sensitivity of 86 % and a specificity of 92 %. CONCLUSIONS: In patients with RCC and tumour thrombus in the renal vein or IVC, the 3D texture analysis based on ADC-map allows for precise differentiation of a solid from a friable thrombus.
- MeSH
- Diffusion Magnetic Resonance Imaging methods MeSH
- Adult MeSH
- Carcinoma, Renal Cell * diagnostic imaging pathology complications MeSH
- Middle Aged MeSH
- Humans MeSH
- Kidney Neoplasms * diagnostic imaging pathology complications MeSH
- Prognosis MeSH
- Retrospective Studies MeSH
- Aged MeSH
- Thrombectomy methods MeSH
- Thrombosis * diagnostic imaging pathology MeSH
- Vena Cava, Inferior diagnostic imaging pathology MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
This paper summarizes information about 16 measuring methods for determining the radon diffusion coefficient of waterproofing materials. We have found that the differences in results for identical membranes, which can be as high as two orders of magnitude, can mainly be attributed to insufficient duration of the tests, insufficient radon concentration to which the samples are exposed, and the use of steady state calculation procedures for data measured under non-steady state conditions.
