External validation of a lung cancer-based prediction model for two-year mortality in esophageal cancer patient cohorts

PURPOSE/OBJECTIVE

Chemo-radiotherapy can improve the oncological outcome of esophageal cancer (EC) patients, but may cause long term radiation-induced toxicity, including an increased risk of non-cancer related death. For lung cancer patients, a model to predict 2-year total mortality using mean heart dose (MHD) and gross tumor volume (GTV) has previously been developed and validated. This project aimed to externally validate this model in EC patients.

METHODS

Five EC patient cohorts from 3 different Dutch centres were used for model validation. External validity of the model was assessed separately in definitive (n = 170) and neo-adjuvant (n = 568) chemoradiotherapy (dCRT and nCRT) patients. External validity was assessed in terms of calibration by calibration plots, calibration-in-the-large (CITL) and calibration slope (CS), and discrimination by assessment of the c-statistic. If suboptimal model performance was observed, the model was further updated accordingly.

RESULTS

For the dCRT patients, good calibration was found after adjustment of the intercept (CITL 0.00; CS 1.08). The c-statistic of the adjusted model was 0.67 (95%CI: 0.58 to 0.75). For nCRT patients the model needed adjustment of both the slope and the intercept because of initial miscalibration in the validation population (CITL 0.00; CS 1.72). After recalibration, the model showed perfect calibration (i.e., CITL 0, CS 1), as is common after recalibration. The c-statistic of the recalibrated model equaled 0.62 (95%CI: 0.57 to 0.67).

CONCLUSION

The existing model for 2-year mortality prediction in lung cancer patients, based on the predictive factors MHD and GTV, showed good performance in EC patients after updating the intercept and/or slope of the original model.

Longitudinal Doppler Assessments in Late Preterm Fetal Growth Restriction

PURPOSE

 To assess the longitudinal variation of the ratio of umbilical and cerebral artery pulsatility index (UCR) in late preterm fetal growth restriction (FGR).

MATERIALS AND METHODS

 A prospective European multicenter observational study included women with a singleton pregnancy, 32^+ 0-36^+ 6, at risk of FGR (estimated fetal weight [EFW] or abdominal circumference [AC] < 10^th percentile, abnormal arterial Doppler or fall in AC from 20-week scan of > 40 percentile points). The primary outcome was a composite of abnormal condition at birth or major neonatal morbidity. UCR was categorized as normal (< 0.9) or abnormal (≥ 0.9). UCR was assessed by gestational age at measurement interval to delivery, and by individual linear regression coefficient in women with two or more measurements.

RESULTS

 856 women had 2770 measurements; 696 (81 %) had more than one measurement (median 3 (IQR 2-4). At inclusion, 63 (7 %) a UCR ≥ 0.9. These delivered earlier and had a lower birth weight and higher incidence of adverse outcome (30 % vs. 9 %, relative risk 3.2; 95 %CI 2.1-5.0) than women with a normal UCR at inclusion. Repeated measurements after an abnormal UCR at inclusion were abnormal again in 67 % (95 %CI 55-80), but after a normal UCR the chance of finding an abnormal UCR was 6 % (95 %CI 5-7 %). The risk of composite adverse outcome was similar using the first or subsequent UCR values.

CONCLUSION

 An abnormal UCR is likely to be abnormal again at a later measurement, while after a normal UCR the chance of an abnormal UCR is 5-7 % when repeated weekly. Repeated measurements do not predict outcome better than the first measurement, most likely due to the most compromised fetuses being delivered after an abnormal UCR.

Radiomics biopsy signature for predicting survival in patients with spinal bone metastases (SBMs)

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Prediction of survival is crucial for guiding patient-tailored treatment.

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Radiomics can be described as the next era of possibilities in precision medicine.

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Radiomics model had an inferior performance with no added predictive power to the clinical predictive model.

Study design

Retrospective analysis of a registered cohort of patients treated and irradiated for metastases in the spinal column in a single institute.

Objective

This is the first study to develop and internally validate radiomics features for predicting six-month survival probability for patients with spinal bone metastases (SBM).

Background data

Extracted radiomics features from routine clinical CT images can be used to identify textural and intensity-based features unperceivable to human observers and associate them with a patient survival probability or disease progression.

Methods

A study was conducted on 250 patients treated for metastases in the spinal column irradiated for the first time between 2014 and 2016, at the MAASTRO clinic in Maastricht, the Netherlands. The first 150 available patients were used to develop the model and the subsequent 100 patient were considered as a test set for the model. A bootstrap (B = 400) stepwise model selection, which combines both the forward and backward variable elimination procedure, was used to select the most useful predictive features from the training data based on the Akaike information criterion (AIC). The stepwise selection procedure was applied to the 400 bootstrap samples, and the results were plotted as a histogram to visualize how often each variable was selected. Only variables selected more than 90 % of the time over the bootstrap runs were used to build the final model.

A prognostic index (PI) called radiomics score (radscore) and clinical score (clinscore) was calculated for each patient. The prognostic index was not scaled, the original values were used which can be extracted from the model directly or calculated as a linear combination of the variables in the model multiplied by the respective beta value for each patient.

Results

The clinical model had a good discrimination power. The radiomics model, on the other hand, had an inferior performance with no added predictive power to the clinical model. The internal imaging characteristics do not seem to have a value in the prediction of survival. However, the Shape features were excluded from further analyses in our study since all biopsies had a standard shape hence no variability.

Fetal cerebral Doppler changes and outcome in late preterm fetal growth restriction: prospective cohort study

OBJECTIVES

To explore the association between fetal umbilical and middle cerebral artery (MCA) Doppler abnormalities and outcome in late preterm pregnancies at risk of fetal growth restriction.

METHODS

This was a prospective cohort study of singleton pregnancies at risk of fetal growth restriction at 32 + 0 to 36 + 6 weeks of gestation, enrolled in 33 European centers between 2017 and 2018, in which umbilical and fetal MCA Doppler velocimetry was performed. Pregnancies were considered at risk of fetal growth restriction if they had estimated fetal weight and/or abdominal circumference (AC) < 10^th percentile, abnormal arterial Doppler and/or a fall in AC growth velocity of more than 40 percentile points from the 20-week scan. Composite adverse outcome comprised both immediate adverse birth outcome and major neonatal morbidity. Using a range of cut-off values, the association of MCA pulsatility index and umbilicocerebral ratio (UCR) with composite adverse outcome was explored.

RESULTS

The study population comprised 856 women. There were two (0.2%) intrauterine deaths. Median gestational age at delivery was 38 (interquartile range (IQR), 37-39) weeks and birth weight was 2478 (IQR, 2140-2790) g. Compared with infants with normal outcome, those with composite adverse outcome (n = 93; 11%) were delivered at an earlier gestational age (36 vs 38 weeks) and had a lower birth weight (1900 vs 2540 g). The first Doppler observation of MCA pulsatility index < 5^th percentile and UCR Z-score above gestational-age-specific thresholds (1.5 at 32-33 weeks and 1.0 at 34-36 weeks) had the highest relative risks (RR) for composite adverse outcome (RR 2.2 (95% CI, 1.5-3.2) and RR 2.0 (95% CI, 1.4-3.0), respectively). After adjustment for confounders, the association between UCR Z-score and composite adverse outcome remained significant, although gestational age at delivery and birth-weight Z-score had a stronger association.

CONCLUSION

In this prospective multicenter study, signs of cerebral blood flow redistribution were found to be associated with adverse outcome in late preterm singleton pregnancies at risk of fetal growth restriction. Whether cerebral redistribution is a marker describing the severity of fetal growth restriction or an independent risk factor for adverse outcome remains unclear, and whether it is useful for clinical management can be answered only in a randomized trial. © 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

On the accuracy of localization achievable in fiducial-based stereoscopic image registration system using an electronic portal imaging device

Portal imaging using electronic portal imaging device (EPID) is a well-established image-guided radiation therapy (IGRT) technique for external beam radiation therapy. The aims of this study are threefold; (i) to assess the accuracy of isocentre localization in the fiducial-based stereoscopic image registration, (ii) to investigate the impact of errors in the beam collimation device on stereoscopic registration, and (iii) to evaluate the intra- and inter-observer variability in stereoscopic registration. Portal images of a ball bearing phantom were acquired and stereoscopic image registrations were performed based on a point centred in the ball bearing as the surrogate for registration. Experiments were replicated by applying intentional offsets in the beam collimation device to simulate collimation errors. The accuracy of fiducial markers localization was performed by repeating the experiment using three spherical lead shots implanted in a pelvic phantom. Portal images of pelvis phantom were given to four expert users to assess the inter-observer variability in performing registration. The isocentre localization accuracy tested using ball bearing phantom was within 0.3 mm. Gravity-induced systematic errors of beam collimation device by 2 mm resulted in positioning offsets of the order of 2 mm opposing the simulated errors. Relatively large inter-portal pair projection errors ranges from 1.3 mm to 1.8 mm were observed with simulated errors in the beam collimation device. The intra-user and inter-user variabilities were observed to be 0.8 and 0.4 mm respectively. Fiducial-based stereoscopic image registration using EPID is robust for IGRT procedure.

Dosimetric impact of systematic MLC positional errors on step and shoot IMRT for prostate cancer: a planning study

The positional accuracy of multileaf collimators (MLC) is crucial in ensuring precise delivery of intensity-modulated radiotherapy (IMRT). The aim of this planning study was to investigate the dosimetric impact of systematic MLC positional errors on step and shoot IMRT of prostate cancer. A total of 12 perturbations of MLC leaf banks were introduced to six prostate IMRT treatment plans to simulate MLC systematic positional errors. Dose volume histograms (DVHs) were generated for the extraction of dose endpoint parameters. Plans were evaluated in terms of changes to the defined endpoint dose parameters, conformity index (CI) and healthy tissue avoidance (HTA) to planning target volume (PTV), rectum and bladder. Negative perturbations of MLC had been found to produce greater changes to endpoint dose parameters than positive perturbations of MLC (p < 0.01). Negative and positive asynchronised MLC perturbations of -1 mm resulted in median changes in D(95) of -1.2 and 0.9% respectively. Negative and positive synchronised MLC perturbations of 1 mm in one direction resulted in median changes in D(95) of -2.3 and 1.8% respectively. Doses to rectum were generally more sensitive to systematic MLC errors compared to bladder (p < 0.01). Negative and positive synchronised MLC perturbations of 1 mm in one direction resulted in median changes in endpoint dose parameters of rectum and bladder from 1.0 to 2.5%. Maximum reduction of -4.4 and -7.3% were recorded for conformity index (CI) and healthy tissue avoidance (HTA) respectively due to synchronised MLC perturbation of 1 mm. MLC errors resulted in dosimetric changes in IMRT plans for prostate.

Management of severe postpartum haemorrhage by uterine artery embolization

We report a case of postpartum haemorrhage which was successfully treated by embolization of the uterine artery. This technique is not well known and is thought to be underused in this condition. We wish to alert medical personnel to its role in this life-threatening situation.

Validation of the Quintero staging system for twin-twin transfusion syndrome

OBJECTIVE

To validate an established staging system for twin-twin transfusion syndrome.

METHODS

Prospective observational study in a tertiary referral fetal medicine center of 52 consecutive cases of twin-twin transfusion syndrome. Each pregnancy was assessed longitudinally for a variety of prognostic factors including fetal biometry, amniotic fluid volume, arterial and venous Doppler sonogram abnormalities, and the presence of hydrops. Data were used to determine stage at diagnosis and first treatment, and worst stage throughout pregnancy. Perinatal outcome was assessed by stage. Management comprised serial amnioreduction, septostomy, selective reduction, or delivery, alone or in combination.

RESULTS

Median gestation at presentation and first treatment were both 21 weeks (range 14-34 and 15-34), and at delivery it was 29 weeks (range 16-40). Sixty-three percent of pregnancies (33 of 52) were at least stage III at presentation. Forty-five percent of pregnancies (22 of 49) progressed to a more advanced stage. Overall survival was 47% (47 of 100), with no difference between donor and recipient fetuses (40% [20 of 50] versus 54% [27 of 50] [chi(2) P =.5]). Survival rates were 58% (15 of 26), 60% (six of ten), 42% (20 of 48), 43% (six of 14), and 0% (none of two) for stages I-V, respectively, with no significant influence of stage at presentation on survival. Survival was poorer where stage increased, versus decreased (27% [12 of 44] versus 94% [17 of 18] chi(2) P <.001). Kaplan-Meier survival curves indicated that staging at presentation identified pregnancies at greater risk of earlier rather than later gestational perinatal loss.

CONCLUSION

The Quintero staging system did not distinguish good from bad outcome at presentation, and thus should be used with caution in guiding initial management of twin-twin transfusion syndrome. However, prognosis was influenced by a change in stage, and pregnancies progressing to higher stage disease were at increased risk of earlier perinatal loss. Staging may thus be more useful in monitoring disease progression.

Influence of twin-twin transfusion syndrome on fetal cardiovascular structure and function: prospective case-control study of 136 monochorionic twin pregnancies

OBJECTIVE

To test the hypothesis that identical twins show no inter-twin differences in cardiovascular structure or physiology in fetal life unless there has been twin-twin transfusion syndrome.

DESIGN

Unselected prospective case-control observational study of fetoplacental haemodynamics including echocardiography at a median of 24 (16.7 to 32.3) weeks, with postnatal confirmation of congenital heart disease or normality.

SETTING

Fetal medicine unit.

PATIENTS

136 women with monochorionic diamniotic twin pregnancies, of which 47 fetal twin pairs (35%) had twin-twin transfusion syndrome.

RESULTS

There were no haemodynamic differences between the bigger fetus (twin 1) and the smaller co-twin (twin 2) in uncomplicated monochorionic diamniotic pairs. In twin-twin transfusion syndrome, recipient fetuses had increased aortic and pulmonary velocities compared with their donor co-twins (mean (SD): 0.73 (0.23) m/s and 0.63 (0.14) m/s), respectively, v 0.53 (0.16) m/s and 0.48 (0.10) m/s in donor twins; p = 0.003 (aortic) and < 0.0001 (pulmonary)), and also in comparison with twin 1 and twin 2. The overall prevalence of congenital heart disease was increased above that in singletons (3.8% v 0.56%; 6.9% in twin-twin transfusion v 2.3% in uncomplicated monochorionic diamniotic twins), with inter-twin discordance for defects. The prevalence in recipient twins was 11.9% (p = 0.014 v uncomplicated control twins).

CONCLUSIONS

Fetuses with an identical genome but no circulatory imbalance have similar cardiovascular physiology but discordant phenotypic expression of congenital heart disease. The high prevalence of congenital heart disease in monochorionic diamniotic twins merits detailed fetal echocardiography.

Central nerve block and coagulation: a survey of obstetric anaesthetists

We conducted a survey amongst anaesthetists in 264 obstetric units in the UK to examine their practice in relation to potential clotting abnormalities. The survey was conducted between July and November 1998 and shows a varied opinion and practice. We received a return of 226 (86%) with 64-78% of respondents willing to perform a central nerve block at a platelet count of 80 x 10(9)/L or more. Patients on aspirin alone or aspirin and heparin would be given a central nerve block by up to 96% and 43% of respondents respectively. Following administration of heparin, up to 22% of respondents would perform a central nerve block within 2 h while up to 64% would wait beyond 4 h. Eighty-five units had departmental policies on the removal of epidural catheters but only 15 differentiated between unfractionated and low molecular weight heparin.

The management of eclampsia by obstetric anaesthetists in UK: a postal survey

Eclampsia and pre-eclampsia are major causes of morbidity and mortality in the obstetric population. The latest triennial report on Confidential Enquiries into Maternal Deaths found hypertensive disorders of pregnancy to be the second most common cause of maternal deaths directly attributable to pregnancy. The management of eclampsia includes the control and prevention of further convulsions by pharmacological methods but the choice of drugs may vary. Current evidence supports the use of magnesium sulphate as the drug of first choice for treating eclampsia. Until recently, UK clinicians used other anticonvulsants for this purpose. Questionnaire studies conducted amongst UK obstetricians published in 1991 and 1998 showed that magnesium sulphate was used in the management of severe pre-eclampsia by 2% and 40% of clinicians respectively. We conducted a survey among lead obstetric anaesthetists in 264 obstetric units in the UK to examine their current practice. We also asked how magnesium was used and included a question on the use of nimodipine. The response rate was 86%. Our results show that magnesium sulphate is used for the treatment of eclampsia in 90% of units and for severe pre-eclampsia in 68%. Most administered magnesium for 24-48 h while nimodipine was used by very few units.

Quantitative analysis of cytokeratin 20 gene expression using RT-PCR and capillary electrophoresis with fluorescent DNA detection

OBJECTIVE

We developed a quantitative reverse-transcription polymerase chain reaction (RT-PCR) to determine CK20 expression in colorectal tumor and hematopoietic tissue.

DESIGN AND METHODS

Our method incorporates a calibrated PCR with an internal competitor and an external standard.

RESULTS

The RT-PCR assay is sensitive detecting 10 target molecules of CK20 in solution with one round of 38 amplification cycles. Genomic DNA contamination was eliminated by Dnase I digestion of total RNA. The inclusion of a calibrator in the quantitative RT-PCR analysis allowed for a high throughput of unknown samples within the same assay improving comparative analysis between the samples tested. Analysis of peripheral blood and bone marrow from 20 healthy volunteers revealed a low level of CK20 expression in all samples.

CONCLUSION

To study the clinical significance of CK20 expression as a marker of systemic metastatic disease it is essential to measure CK20 mRNA levels in hematopoietic tissue with sensitive quantitative RT-PCR. A sensitive and reproducible method, which is easily performed, is described.

Sensitive and quantitative one-step polymerase chain reaction using capillary electrophoresis and fluorescence detection for measuring cytokeratin 19 expression

An improved quantitative assay to measure cytokeratin 19 (CK19) expression has been developed. The assay utilizes reverse transcription and a one-step polymerase chain reaction (PCR), with capillary electrophoresis and fluorescent labelling, to separate and detect the PCR products. Calibration curves were constructed from a serial dilution of CK19 cDNA coamplified with a fixed amount of CK19 internal standard, which was found to be linear between 10 and 500 molecules. Quantitative measurement of CK19 in samples was carried out by coamplifying the cDNA with a fixed amount of internal standard. The values were calculated from the calibration curve. The integrity of RNA and cDNA synthesis was checked by quantitative measurement of the breakpoint cluster region (BCR) gene expression. The assay is sensitive, detecting < 10 CK19 transcripts, and reproducible with a coefficient of variation of approximately 10%. CK19 expression showed overlapping values when measured in samples from peripheral blood and bone marrow in operable breast cancer patients, in healthy volunteers or patients without epithelial cancer and in blood samples from patients with metastatic breast cancer. As the assay is easier to perform than traditional quantitative competitive PCR assays, it might be useful for quantitative measurement of other specific transcripts.

Bladder exstrophy in a neonate at risk of transient myasthenia gravis: a role for remifentanil and epidural analgesia

Infants born to mothers with myasthenia gravis may exhibit a transient form of the disease, with similar sensitivity to non-depolarizing neuromuscular blocking drugs. We report the case of an infant at risk who required major surgery when 48 h old for closure of bladder exstrophy. A combined epidural-general anaesthetic technique, with remifentanil supplementation, enabled us to avoid unnecessary neuromuscular blocking drugs and prolonged intensive care, which had been anticipated. The potential benefits of remifentanil and epidural analgesia in neonates are discussed.