Accuracy and precision of apparent diffusion coefficient measurements on a 1.5 T MR-Linac in central nervous system tumour patients

Background and purpose: MRI linear accelerators (MR-Linacs) may allow treatment adaptation to be guided by quantitative MRI including diffusion-weighted imaging (DWI). The aim of this study was to evaluate the accuracy and precision of apparent diffusion coefficient (ADC) measurements from DWI on a 1.5 T MR-Linac in patients with central nervous system (CNS) tumours through comparison with a diagnostic scanner. Materials and methods: CNS patients were treated using a 1.5 T Elekta Unity MR-Linac. DWI was acquired during MR-Linac treatment and on a Philips Ingenia 1.5 T. The agreement between the two scanners on median ADC over the gross tumour/clinical target volumes (GTV/CTV) and in brain regions (white/grey matter, cerebrospinal fluid (CSF)) was computed. Repeated scans were used to estimate ADC repeatability. Daily changes in ADC over the GTV of high-grade gliomas were characterized from MR-Linac scans. Results: DWI from 59 patients was analyzed. MR-Linac ADC measurements showed a small bias relative to Ingenia measurements in white matter, grey matter, GTV, and CTV (bias: –0.05 ± 0.03, –0.08 ± 0.05, –0.1 ± 0.1, –0.08 ± 0.07 μm2/ms). ADC differed substantially in CSF (bias: –0.5 ± 0.3 μm2/ms). The repeatability of MR-Linac ADC over white/grey matter was similar to previous reports (coefficients of variation for median ADC: 1.4%/1.8%). MR-Linac ADC changes in the GTV were detectable. Conclusions: It is possible to obtain ADC measurements in the brain on a 1.5 T MR-Linac that are comparable to those of diagnostic-quality scanners. This technical validation study adds to the foundation for future studies that will correlate brain tumour ADC with clinical outcomes

Routines in facility-based maternity care: Evidence from the Arab World

OBJECTIVES: To document facility-based practices for normal labour and delivery in Egypt, Lebanon, the West Bank (part of the Occupied Palestinian Territory) and Syria and to categorise common findings according to evidence-based obstetrics. DESIGN: Three studies (Lebanon, West Bank and Syria) interviewed a key informant (providers) in maternity facilities. The study in Egypt directly observed individual labouring women. SETTING: Maternity wards. SAMPLE: Nationally representative sample of hospitals drawn in Lebanon and Syria. In the West Bank, a convenience sample of hospitals was used. In Egypt, the largest teaching hospital's maternity ward was observed. METHODS: Shared practices were categorised by adapting the World Health Organization's (WHO) 2004 classification of practices for normal birth into the following: practices known to be beneficial, practices likely to be beneficial, practices unlikely to be beneficial and practices likely to be ineffective or harmful. MAIN OUTCOME MEASURES: Routine hospital practices for normal labor and delivery. RESULTS: There was infrequent use of beneficial practices that should be encouraged and an unexpectedly high level of harmful practices that should be eliminated. Some beneficial practices were applied inappropriately and practices of unproven benefit were also documented. Some documented childbirth practices are potentially harmful to mothers and their babies. CONCLUSION: Facility practices for normal labour were largely not in accordance with the WHO evidence-based classification of practices for normal birth. The findings are worrying given the increasing proportion of facility-based births in the region and the improved but relatively high maternal and neonatal mortality ratios in these countries. Obstacles to following evidence-based protocols for normal labour require examination