RESUMEN
OBJECTIVES: To measure dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) biomarker repeatability in patients with non-small cell lung cancer (NSCLC). To use these statistics to identify which individual target lesions show early biological response. MATERIALS AND METHODS: A single-centre, prospective DCE-MRI study was performed between September 2015 and April 2017. Patients with NSCLC were scanned before standard-of-care radiotherapy to evaluate biomarker repeatability and two weeks into therapy to evaluate biological response. Volume transfer constant (Ktrans), extravascular extracellular space volume fraction (ve) and plasma volume fraction (vp) were measured at each timepoint along with tumour volume. Repeatability was assessed using a within-subject coefficient of variation (wCV) and repeatability coefficient (RC). Cohort treatment effects on biomarkers were estimated using mixed-effects models. RC limits of agreement revealed which individual target lesions changed beyond that expected with biomarker daily variation. RESULTS: Fourteen patients (mean age, 67 years +/- 12, 8 men) had 22 evaluable lesions (12 primary tumours, 8 nodal metastases, 2 distant metastases). The wCV (in 8/14 patients) was between 9.16% to 17.02% for all biomarkers except for vp, which was 42.44%. Cohort-level changes were significant for Ktrans and ve (p < 0.001) and tumour volume (p = 0.002). Ktrans and tumour volume consistently showed the greatest number of individual lesions showing biological response. In distinction, no individual lesions had a real change in ve despite the cohort-level change. CONCLUSION: Identifying individual early biological responders provided additional information to that derived from conventional cohort cohort-level statistics, helping to prioritise which parameters would be best taken forward into future studies. CLINICAL RELEVANCE STATEMENT: Dynamic contrast-enhanced magnetic resonance imaging biomarkers Ktrans and tumour volume are repeatable and detect early treatment-induced changes at both cohort and individual lesion levels, supporting their use in further evaluation of radiotherapy and targeted therapeutics. KEY POINTS: Few literature studies report quantitative imaging biomarker precision, by measuring repeatability or reproducibility. Several DCE-MRI biomarkers of lung cancer tumour microenvironment were highly repeatable. Repeatability coefficient measurements enabled lesion-specific evaluation of early biological response to therapy, improving conventional assessment.
RESUMEN
PURPOSE: Hypoxia mediates treatment resistance in solid tumors. We evaluated if oxygen-enhanced (OE)-MRI-derived hypoxic volume (HVMRI) is repeatable and can detect radiotherapy-induced hypoxia modification in HPV-associated oropharyngeal head and neck squamous cell cancer (HNSCC). EXPERIMENTAL DESIGN: 27 patients were recruited prospectively between March 2021 and January 2024. HVMRI was measured in primary and nodal tumors prior to standard-of-care (chemo)radiotherapy then at weeks 2 and 4 (W2, W4) into therapy. Two pre-treatment scans assessed biomarker within-subject coefficient of variation (wCV) and repeatability coefficient (RC). Cohort treatment response was measured using mixed-effects modelling. Responding lesions were identified by comparing HVMRI change to RC limits of agreement (LOA). RESULTS: OE-MRI identified hypoxia in all lesions. HVMRI wCV was 24.6% and RC LOA were -45.7% to 84.1%. Cohort median pre-treatment HVMRI of 11.3 cm3 reduced to 6.9 cm3 at W2 and 5.9 cm3 at W4 (both p < 0.001). HVMRI was reduced in 54.5% of individual lesions by W2 and in 88.2% by W4. All lesions with W2 hypoxia reduction showed persistent modification at W4. HVMRI reduced in some lesions that showed no overall volume change. Hypoxia modification was discordant between primary and nodal tumors in 50.0% of patients. CONCLUSIONS: Radiation-induced hypoxia modification can occur as early as W2, but onset varies between patients and was not necessarily associated with overall size change. Half of all patients had discordant changes in primary and nodal tumors. These findings have implications for patient selection and timing of dose de-escalation strategies in HPV-associated oropharyngeal carcinoma.
RESUMEN
CONTEXT: Induction of general anesthesia and mandatory low-ambient temperature in the magnetic resonance imaging (MRI) suite renders the pediatric patient prone to fall in core temperature. Previously done studies have shown mixed results with core temperature showing both rise and fall. AIMS: The aim of this study is to evaluate which effect, hypothermia or hyperthermia, predominates in children anesthetized for MRI. Is the change in temperature the same across age groups and for different MRI scanners?. SETTINGS AND DESIGN: Prospective, observational study in a tertiary care teaching hospital. SUBJECTS AND METHODS: Two hundred and fifty children of age between 1 month and 16 years scheduled for MRI under propofol-based total intravenous anesthesia (TIVA) were recruited. A baseline core temperature (pre-scan) was recorded with the pediatric nasopharyngeal temperature probe after induction of anesthesia and also after the scan in the recovery room. RESULTS: The study shows that there is a significant fall in temperature of 1.022°C (CI = 0.964, 1.081) following MRI (P < 0.001) but the difference across different age groups and type of MRI scanner used are not significant. There is a significant correlation between duration in the MRI room and a decrease in temperature (P value = 0.003). Using simple linear regression analysis, it is found that if there is a 1-min increase in the duration of MRI, there is a decrease of 0.006°C in temperature. CONCLUSION: Vigilant temperature preservation strategies have to be maintained during the time the anesthetized child is present in the MRI suite. MRI compatible active warming devices are warranted especially in high turnover centers.