In this study we investigated the interchangeability of planning CT and cone-beam CT (CBCT) extracted radiomic features. Furthermore, a previously described CT based prognostic radiomic signature for non-small cell lung cancer (NSCLC) patients using CBCT based features was validated.One training dataset of 132 and two validation datasets of 62 and 94stage I-IV NSCLC patients were included. Interchangeability was assessed by performing a linear regression on CT and CBCT extracted features. A two-step correction was applied prior to model validation of a previously published radiomic signature. Results 13.3% (149 out of 1119) of the radiomic features, including all features of the previously published radiomic signature, showed an R2 above 0.85 between intermodal imaging techniques. For the radiomic signature, Kaplan-Meier curves were significantly different between groups with high and low prognostic value for both modalities. Harrell's concordance index was 0.69 for CT and 0.66 for CBCT models for dataset 1. Conclusions The results show that a subset of radiomic features extracted from CT and CBCT images are interchangeable using simple linear regression. Moreover, a previously developed radiomics signature has prognostic value for overall survival in three CBCT cohorts, showing the potential of CBCT radiomics to be used as prognostic imaging biomarker.
The Mapleson A, B, C and D circuits can be changed into non‐polluting circuits by employing continuous gas evacuation directly from the circuit, via an ejector flowmeter (J ørgensen 1974); Mapleson A and C circuits with this modification have been described previously as the Hafnia A and C circuits (C hristensen 1976, T homsen & J ørgensen 1976). If evacuation from a closed reservoir is employed, total removal of the expired and surplus gases from the operating theatre is obtained (J ørgensen & T homsen 1976). There will be resistance to expiration in all the circuits with a relief valve for the discharge of surplus gas. If surplus gas is continuously removed directlyfrom the anaesthetic circuit, the patient breathes in an air compartment at ambient pressure, as long as the removal rate equals the inflow of fresh gas. The relief valve is only included in the circuit to ensure that high pressures do not develop. As in any other circuit, the relief valve remains open except during controlled ventilation. A dumping valve may also be included as a safeguard against low pressures (J ørgensen & T homsen 1976). The flow requirements of the Hafnia B and D circuits and the corresponding Mapleson circuits have been studied in conscious, spontaneously breathing subjects, and the results are discussed in relation to the flow requirements of other semi‐closed systems.
Rat mesenteric resistance vessels (RV) were characterized with respect to concentration of individual alpha-subunit isoforms of Na,K-ATPase.Total vessel homogenates were used to avoid any loss or subfractionation of membranes. They were applied to sodium dodecyl sulphate gels and, for calibration, in parallel lanes were run purified rat Na,K-ATPase preparations with known isoform distribution and content. The capacity per mg protein for Na+-dependent 32P-phosphorylation of Na,K-ATPase isolated from rat kidney was used for alpha1 calibration and that for high-affinity (3H)ouabain binding of Na,K-ATPase isolated from rat brain was used for (alpha2 + alpha3) calibration. Western blots containing homogenate proteins and reference enzyme were incubated with isoform-specific antibodies and radiolabelled secondary antibodies. The signals from adjacent alpha spots were used for qualitative and quantitative characterization of rat vessels.A concentration of 100.7 +/- 14.4 pmol (n = 11) per g wet weight of the alpha1-isoform containing Na,K-ATPase was found in RV from 12-14-week rats. A much lower and more unreliable content of alpha2- and alpha3-isoforms was found. These ouabain-sensitive isoforms seem to represent a maximum of 5-10% each compared with the ouabain-insensitive rat alpha1-isoform.The isoform pattern in RV, in which the isoform with high/intermediate Na+-affinity is the absolutely dominating one representing nearly all sodium pumps in this tissue, is very different from that seen in rat skeletal muscles. Due to the high content of the ouabain-insensitive alpha1-isoform in rat RV this species would seem a less relevant model in studies addressing a role of cardiac glycosides and putative endogenous ouabain-like factors in hypertension.
The impact of dietary sodium on the incidence of nursing sickness in mink dams and on the average litter biomass of 28 and 42 day old kits was studied. One group (n = 115 including 12 barren females) was given a standard feed mixture with a natural content of 0.53 g NaCl/MJ and another group (n = 115 including 8 barren females) was given the same feed mixture supplemented with NaCl to a final content of 1.00 g/MJ. The average dam weight at weaning was significantly lower (P < 0.001) and the incidence of nursing sickness during the last part of the lactation period 3 times higher in the nonsupplemented group. The average litter biomass at weaning did not differ between the 2 experimental groups. A number of biochemical markers of preclinical nursing sickness, e.g. plasma aldosterone and osmolality, Na+ and Cl concentrations in plasma and urine, were studied during the last part of the lactation period and at weaning in 20 dams of the nonsupplemented group, in 10 dams of the salt supplemented group and, for comparison, in 5 + 5 barren females on the day corresponding to day 34 after parturition in nursing mink. The nonsupplemented group had significantly lower concentrations of sodium and chloride in plasma and urine and a significantly higher concentration of plasma aldosterone as compared to the salt supplemented group. Distinct signs of relative salt deficiency and preclinical nursing sickness thus characterized the nonsupplemented group throughout this period, while more blurred hints of electrolyte imbalances were noticed in the sodium chloride supplemented group at weaning. A beneficial effect of salt supplementation on the incidence of nursing sickness was shown; however, it remains unclear whether salt deficiency can cause nursing sickness or whether salt acts as an appetite stimulant preventing inanition and the development of the disorder.
With daily, MR-guided online adapted radiotherapy (MRgART) it may be possible to reduce the PTV in pelvic RT. This study investigated the potential reduction in normal tissue complication probability (NTCP) of MRgART compared to standard radiotherapy for high-risk prostate cancer.Twenty patients treated with 78 Gy to the prostate and 56 Gy to elective pelvic lymph nodes were included. VMAT plans were generated with standard clinical PTV margins. Additionally to the planning MR, patients had three MRI scans during treatment to simulate an MRgART. A reference plan with PTV margins determined for MRgART was created per patient and adapted to each of the following MRs. Adapted plans were warped to the planning MR for dose accumulation. The standard plan was rigidly registered to each adaptation MR before it was warped to the planning MR for dose accumulation. Dosimetric impact was compared by DVH analysis and potential clinical effects were assessed by NTCP modeling.MRgART yielded statistically significant lower doses for the bladder wall, rectum and peritoneal cavity, compared to the standard RT, which translated into reduced median risks of urine incontinence (ΔNTCP 2.8%), urine voiding pain (ΔNTCP 2.8%) and acute gastrointestinal toxicity (ΔNTCP 17.4%). Mean population accumulated doses were as good or better for all investigated OAR when planned for MRgART as standard RT.Online adapted radiotherapy may reduce the dose to organs at risk in high-risk prostate cancer patients, due to reduced PTV margins. This potentially translates to significant reductions in the risks of acute and late adverse effects.
