To retrospectively determine the effect of liver iron deposition on the evaluation of liver fat by using opposed-phase magnetic resonance (MR) imaging.
Committee on Human Research approval was ...obtained, and compliance with HIPAA regulations was observed. Patient consent was waived by the committee. Thirty-eight patients with cirrhosis (30 men, eight women; mean age, 58 years; range, 34-76 years) who underwent abdominal MR imaging and had contemporaneous liver biopsy were retrospectively identified. Two radiologists independently quantified liver fat according to the relative loss of signal intensity and compared this loss on opposed-phase and in-phase T1-weighted gradient-echo images. Liver fat percentage and presence of iron deposition were independently recorded by a pathologist. Generalized linear models, which included a mixed-random effects model, were used to determine the effect of iron deposition on the Spearman correlation coefficient for relative signal intensity loss versus histopathologically determined fat percentage.
Liver iron deposition was found in 25 of 38 patients. Liver fat percentage (mean, 3%; range, 0%-25%) was identified histopathologically in 14 of 38 patients and in nine of 25 patients with iron deposition. For both readers, relative signal intensity loss at opposed-phase imaging was closely and significantly correlated (P < .05) with histopathologically determined liver fat percentage in patients without iron deposition (r = 0.7 for reader 1, r = 0.6 for reader 2), but no such correlation was found in patients with iron deposition (r = 0.1 for reader 1, r = -0.31 for reader 2; P > .05).
Signal intensity loss on in-phase images caused by the presence of liver iron is a potential pitfall in the determination of liver fat percentage at opposed-phase MR imaging in chronic liver disease.
Objectives
To assess the ability of multiparametric MRI (mp-MRI) of the prostate to exclude prostate cancer (PCa) progression during monitoring patients on active surveillance (AS).
Methods
One ...hundred forty-seven consecutive patients on AS with mp-MRI (T2WI, DWI, DCE-MRI) at 3T were initially enrolled. Fifty-five received follow-up mp-MRI after a minimum interval of 12 months and subsequent targeted MR/US fusion-guided biopsy (FUS-GB) plus concurrent systematic transrectal ultrasound-guided (TRUS-GB) biopsy as reference standard. Primary endpoint was the negative predictive value (NPV) of the follow-up mp-MRI to exclude histopathologic tumor progression using PRECISE recommendations. Secondary endpoints were the positive predictive value (PPV), sensitivity, specificity, Gleason score (GS) upgrades, and comparison of biopsy method.
Results
Of 55 patients, 29 (53%) had a GS upgrade on re-biopsy. All 29 patients showed a tumor progression on follow-up mp-MRI. Fifteen of 55 patients (27%) displayed signs of tumor progression, but had stable GS on re-biopsy. None of the 11 patients (20%) without signs of progression on follow-up mp-MRI had a GS upgrade on re-biopsy. The NPV was 100%, PPV was 66%, sensitivity was 100%, and specificity 42%. FUS-GB resulted in GS upgrade significantly more often (
n
= 28; 51%) compared with TRUS-GB (
n
= 12; 22%;
p
< 0.001).
Conclusions
(Follow-up) Mp-MRI can reliably exclude PCa progression in patients on AS. Standard serial re-biopsies might be waived if follow-up mp-MRIs are stable. Over 60% of patients with signs of tumor progression on mp-MRI during AS had a GS upgrade on re-biopsy. Targeted re-biopsies should be performed if cancer progression or higher-grade PCa is suspected on mp-MRI.
Key Points
•
None of the patients with unsuspicious mp-MRI had a GS upgrade in re-biopsy and mp-MRI might replace serial biopsies in these cases
•
More than 60% of patients with mp-MRI signs of tumor progression had subsequent Gleason score (GS) upgrades
• Targeted re-biopsies should be performed in case of higher GS cancer suspicion on mp-MRI
Aim
To compare the dissolution time of two solutions, a fluoride solution and a sodium hypochlorite solution, both saturated with sodium chloride, during the electrochemical dissolution of ...instruments consisting of conventional nickel‐titanium alloy and Gold thermomechanically treated nickel‐titanium alloy.
Methodology
Two solutions, an NaF solution consisting of 12 g L−1 NaF with 180 g L−1 NaCl and an NaOCl solution consisting of 2.5% NaOCl with 180 g L−1 NaCl, were evaluated in a polarization test of a sample of 48 ProTaper Universal F1 (PTU F1) and WaveOne Gold Small (WOGS) instruments. The electric potentials were 0.5 V and 5 V for the NaF and NaOCl solutions, respectively. The electrochemical cell consisted of three electrodes for the polarization test of the PTU F1 and WOGS instruments, which had 6 mm of the tip immersed in the test solutions. The electric current was recorded for 540 s. If complete dissolution of the immersed tip occurred in less than the expected time, the experiment was considered complete. The time variations (in seconds) of the instruments in the solutions were measured. Data were subjected to statistical analysis using the Mann–Whitney, Kruskal–Wallis and Dunn tests. The corrosion patterns of the instruments were evaluated by scanning electron microscopy (SEM).
Results
The NaF and NaOCl solutions were associated with significantly different (P = 0.000) dissolution times of the instrument, with mean values of 12.96 s and 83.63 s, respectively. There was no significant difference (P = 0.649) in dissolution time between the PTU F1 and WOGS instruments.
Conclusions
NaF and NaOCl solutions were able to electrochemically dissolve PTU F1 and WOGS instruments. However, the NaF solution achieved dissolution in significantly less time.
Highlights • We examine the expression of RANKL and OPG in patients with symptomatic apical periodontitis. • We correlate the results with the detected numbers of gram-negative bacteria. • The ...symptomatic group showed a significantly higher number of gram-negative cells. • Gram-negative bacteria may play an important role in OPG activity in patients with symptomatic apical periodontitis. • A higher number of gram-negative bacteria occurred more frequently in larger periapical lesions and SYM group.
Sustainable and efficient design solutions are the aim for any engineer. In offshore engineering forces resulting from extreme wave impact are of special interest as these challenge the structure and ...the crew working in this harsh environment. Theoretical models tend to be limited to linear or weakly non-linear situations and are unable to predict the violent and turbulent effects of breaking waves in combination with wave run up on structures or green water loading. The classic approach for such cases is to carry out scale model tests in a physical wave tank and measure the forces, water levels and flow velocities at some chosen locations.
Another approach is to use fully non-linear calculations, such as Computational Fluid Dynamics, which have the potential to investigate the design in different conditions at full scale. This paper deals with the generation and behaviour of extreme focused wave groups in a numerical wave tank. Non-linear effects of these extreme waves are shown and the implications for a numerical wave tank are discussed. Also the forces on horizontal and vertical cylinders, which represent simple models of offshore structures, are calculated. All numerical results are compared with measured data from physical experiments.
► We use two commercial CFD packages to model wave–structure interaction. ► Extreme focused waves are generated and regular waves interacting with fixed cylinders. ► Use of second order wave signal could improve agreement with physical tank tests significantly. ► Highly non-linear effects such as wave breaking and secondary load cycle can be modelled.
Aim
To assess the effect of sodium chloride concentration in fluoridated solutions during the electrochemical dissolution of fractured rotary endodontic instruments.
Methodology
Two solutions were ...assessed (solution 1: NaF 12 g L−1 + NaCl 1 g L−1, pH = 5.0; and solution 2: NaF 12 g L−1 + NaCl 180 g L−1, pH = 5.0) using two tests: the ProTaper Universal F1 (PTU F1) instrument polarization test and the polarization test for intracanal PTU F1 fragments fractured in mandibular incisors. In the first test, two sets of five instruments were separately and partially immersed in each solution, and the electrical current was evaluated over 30 min. In the second test, 45 PTU F1 instruments were fractured within the root canals of mandibular incisors and subjected to potentiodynamic polarization for 30 min. The electrical current and the variations in the length of PTU F1 fragments were measured. The data were analysed statistically (anova and Wilcoxon and Mann–Whitney tests, respectively).
Results
Solution 2 was associated with more corrosive effects in both tests. In the first test, the PTU F1 instruments immersed in solution 2 had a higher electrical current (P < 0.001) and had a total dissolution time of approximately 540 s. In the second test, a larger difference between the baseline and final lengths of the fragments was noted in solution 2 (P = 0.011).
Conclusion
Saturation of fluoridated solution with sodium chloride led to an increase in electrical current and microscopic reductions in the length of fractured instrument fragments subjected to electrochemical dissolution.
Purpose
To subjectively and quantitatively compare the quality of 3 Tesla magnetic resonance imaging of the prostate acquired with a novel flexible surface coil (FSC) and with a conventional ...endorectal coil (ERC).
Methods
Six radiologists independently reviewed 200 pairs of axial, high-resolution T2-weighted and diffusion-weighted image data sets, each containing one examination acquired with the FSC and one with the ERC, respectively. Readers selected their preferred examination from each pair and assessed every single examination using six quality criteria on 4-point scales. Signal-to-noise ratios were measured and compared.
Results
Two readers preferred FSC acquisition (36.5–45%) over ERC acquisition (13.5–15%) for both sequences combined, and four readers preferred ERC acquisition (41–46%). Analysis of pooled responses for both sequences from all readers shows no significant preference for FSC or ERC. Analysis of the individual sequences revealed a pooled preference for the FSC in T2WI (38.7% vs 17.8%) and for the ERC in DWI (50.9% vs 19.6%). Patients’ weight was the only weak predictor of a preference for the ERC acquisition (
p
= 0.04). SNR and CNR were significantly higher in the ERC acquisitions (
p
<0.001) except CNR differentiating tumor lesions from benign prostate (
p
=0.1).
Conclusion
Although readers have strong individual preferences, comparable subjective image quality can be obtained for prostate MRI with an ERC and the novel FSC. ERC imaging might be particularly valuable for sequences with inherently lower SNR as DWI and larger patients whereas the FSC is generally preferred in T2WI. FSC imaging generates a lower SNR than with an ERC.
To determine the relative accuracy of CT or MR imaging in the detection of inoperable tumor sites prior to cytoreductive surgery in a large series of patients with newly diagnosed primary epithelial ...ovarian cancer.
One hundred thirty-seven women with newly diagnosed primary epithelial ovarian cancer underwent CT (
n = 91) or MR imaging (
n = 46) prior to cytoreductive surgery. The following imaging criteria were used to identify inoperable tumor sites: (1) peritoneal implants greater than 2 cm in maximum diameter in the porta hepatis, intersegmental fissure, gall bladder fossa, subphrenic space, gastrohepatic ligament, gastrosplenic ligament, lesser sac, or root of the small bowel mesentery; (2) retroperitoneal adenopathy greater than 2 cm in maximum diameter above the renal hila; (3) hepatic metastases or abdominal wall invasion. Imaging results were compared with operability at surgery.
Cytoreductive surgery was suboptimal in 21 of the 137 (15%) patients. Sixteen of these patients had inoperable tumor on preoperative imaging, while one additional patient had apparently inoperable tumor on imaging but was optimally debulked at surgery. The sensitivity, specificity, positive predictive value, and negative predictive value of preoperative imaging for the prediction of suboptimal debulking were 76% (16/21), 99% (115/116), 94% (16/17), and 96% (115/120), respectively. CT and MR imaging were equally effective (
P = 1.0) in the detection of inoperable tumor.
Preoperative CT and MR imaging are equally accurate in the detection of inoperable tumor and the prediction of suboptimal debulking in newly diagnosed epithelial ovarian cancer. This suggests imaging may help select patients who might be more appropriately managed by neoadjuvant chemotherapy.
Purpose
The purpose of this study was to compare the PI-RADS V2 scores, ADC histogram-derived parameters, and their combination for the diagnosis of clinically significant peripheral zone prostate ...cancer (PCa).
Materials and Methods
The IRB approved this retrospective study of 47 men who underwent 1.5 Tesla endorectal prostate magnetic resonance imaging (MRI). Informed consent was waived. Two readers identified and scored MRI lesions using PI-RADS V2. Their mean, median, 10th, 25th, 75th percentile ADC values, and normalized ratio were also calculated. Multilevel logistic regression and receiver-operating characteristic (ROC) curve analyses assessed their diagnostic performance. Clinically significant PCa was defined as tumor volume over 0.5 cc and Gleason grade of 4 or 5 on prostatectomy.
Results
The area under the ROC curve (
A
z
) of the overall and diffusion-weighted imaging (DWI) PI-RADS V2 scores were 0.69 and 0.84 (reader-1), and 0.68 and 0.73 (reader-2). The
A
z
of ADC parameters ranged from 0.68 to 0.75 for both readers. Compared to other predictors, DWI PI-RADS V2 yielded the highest
A
z
for identification of significant cancer; but, except for reader-1 75th percentile ADC, the differences were not statistically significant (
P
> 0.05). Adding ADC parameters to PI-RADS V2 scores did not improve their diagnostic ability.
Conclusion
DWI PI-RADS V2 score may a better predictor of clinically significant PCa than the overall PI-RADS V2 score, but its diagnostic performance was not significantly improved by the addition of objective ADC value measurements.
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