Here is the design of a clinical trial:

Official Title: Neuroplasticity Induced by General Anaesthesia

Included conditions:
- Healthy Volunteers
- General Anaesthesia
- Neuroplasticity

Study Armgroups:
- {'label': 'Sevoflurane-Propofol', 'type': 'ACTIVE_COMPARATOR', 'description': 'Session one: Sevoflurane as maintenance anaesthetic during general anaesthesia.\n\nSession two: Propofol as maintenance anaesthetic during general anaesthesia.', 'interventionNames': ['Drug: Sevoflurane-propofol']}
- {'label': 'Propofol-Sevoflurane', 'type': 'ACTIVE_COMPARATOR', 'description': 'Session one: Propofol as maintenance anaesthetic during general anaesthesia.\n\nSession two: Sevoflurane as maintenance anaesthetic during general anaesthesia.', 'interventionNames': ['Drug: Sevoflurane-propofol']}

Interventions:
- {'type': 'DRUG', 'name': 'Sevoflurane-propofol', 'description': 'General anaesthesia with a maintenance phase of two hours duration with either sevoflurane or propofol.', 'armGroupLabels': ['Propofol-Sevoflurane', 'Sevoflurane-Propofol'], 'otherNames': ['Propofol-sevoflurane']}

Primary Outcomes:
- {'measure': 'Changes in T1w3D', 'description': 'Volume and morphology of selected brain regions and anatomical structures as recorded by T1w3D anatomy MRI.', 'timeFrame': '8 days'}
- {'measure': 'Changes in DTI', 'description': 'White matter microstructure as measured using Diffusion Tensor Imaging (DTI)', 'timeFrame': '8 days'}

Please estimate the sample size based on the assumption: 
Significance level of 0.05, power of 0.80, and standard deviation of ±10%. After Bonferroni correction for multiple comparisons, the significance level is adjusted to 0.025.
Sample size
        We base our sample size estimations on the following primary end points: (1) changes in grey-matter volume, and (2) DTI changes. The volunteers will serve as their own controls.
(i)Sample size estimation based on changes in grey-matter volume: we base our sample size estimation for grey-matter volume changes on data extrapolated from the hippocampus. The mean volume of the hippocampus is approximately 2.50 mL (Â±â0.15 standard deviation (SD)) in the healthy population [54]. The pre-operative hippocampal volume has been found to be 6% smaller in patients suffering from POCD compared to patients not suffering from POCD [55]. We assume that GA will affect the grey-matter volume to a larger extent compared to e.g. vulnerability towards POCD. Thus, 25 subjects will be necessary to detect a difference of 8% in the hippocampal volume between groups, applying a two-tailed alpha value of 0.05, SD Â±â10% and a desired power of 0.80(ii)Sample size estimation based on DTI changes: our sample size estimation for detection of DTI changes is also based on data extrapolated from the hippocampus. We assume a 10% change in mean diffusivity, since we expect GA to induce larger changes than, e.g. a learning task by video gaming [56]. With a significance level of 0.05, a power of 80%, a SD of Â±â10%, this indicated a required sample size of 16 volunteers
        
          Correction for multiple comparisons
          Since it should be assumed that grey-matter changes and changes in DTI are inter-dependable variables, the significance level for each sample size estimation should be corrected for multiple comparisons. The desired corrected significance level is 0.025 (significance level of 0.05 Bonferroni corrected for two number of hypothesis). With a SD of Â±â10% and 80% power, this gives a sample size of 30 volunteers regarding detection of statistically significant differences in grey-matter volume. Regarding statistically significant differences in DTI, the calculation gives a sample size of 20 volunteers. We are therefore confident that a sample size of 30 volunteers will be sufficient to ensure the necessary statistical power.