Here is the design of a clinical trial:

Official Title: Neuroinflammation in Cognitive Decline Post-cardiac Surgery: The FOCUS Study

Included conditions:
- Postoperative Cognitive Dysfunction
- Coronary Artery Disease
- Pathophysiology

Study Armgroups:
- {'label': 'POCD', 'description': 'Patients with postoperative cognitive decline (POCD) after coronary artery bypass grafting (CABG) surgery', 'interventionNames': ['Diagnostic Test: 18F-DPA-714 PET/CT neuroimaging']}
- {'label': 'no POCD', 'description': 'Patients without postoperative cognitive decline (POCD) after coronary artery bypass grafting (CABG) surgery', 'interventionNames': ['Diagnostic Test: 18F-DPA-714 PET/CT neuroimaging']}

Interventions:
- {'type': 'DIAGNOSTIC_TEST', 'name': '18F-DPA-714 PET/CT neuroimaging', 'description': '* Pre- and postoperative neuroimaging using 18F-DPA-714 PET/CT and brain MRI.\n* Longitudinal neuropsychological examinations (up to 6 months postoperatively)\n* Blood samples are drawn to assess the severity of the systemic inflammatory response', 'armGroupLabels': ['POCD', 'no POCD']}

Primary Outcomes:
- {'measure': 'Change in TSPO PET tracer uptake at 3-7 days post-surgery', 'description': '18F-DPA-714', 'timeFrame': '3-7 days post-surgery minus preoperative (= day before surgery)'}

Please estimate the sample size based on the assumption: 
An unpaired two-sample t-test with a power of 80% and a one-sided alpha of 0.05. To account for lower increments, 15 patients per group will result in a power of 85% with an alpha of 0.05.
Sample size calculation
        No data on the degree of glial activation after systemic inflammatory responses in post-cardiac surgery patients are available. Research on cognitive dysfunction after cardiac surgery estimates a prevalence of approximately 50% at hospital discharge.1 5 48 Therefore, we will define two groups based on the presence or absence of cognitive dysfunction at hospital discharge.
        Previous studies in dementia patients observed a 15%â35%âhigher PET tracer uptake in patients with cognitive impairment compared with healthy controls, with an SD of 30%.55 56 Therefore, we assume that patients with cognitive dysfunction at hospital discharge after cardiac surgery will have a 30% higher delta tracer uptake compared with patients without cognitive decline. To assess a 30% higher delta tracer uptake in patients with cognitive dysfunction, an unpaired two-sample t-test results in 13 patients per group with a power of 80% and a one-sided alpha of 0.05. In order to account for lower increments we will include 15 patients per group resulting in a power of 85% with an alpha of 0.05 to differentiate an increase of 30% in delta tracer uptake. Consequently, we will include a total of 30 patients, assuming that 50% will have cognitive decline at hospital discharge. The investigator can decide to withdraw a subject from the study for (1) urgent medical reasons or (2) if a protocol violation occurs or (3) if the subject is lost to follow-up. Replacement of individuals will not be necessary in this observational cohort once both PET scans are performed (ie, primary objective has been met).
        Sample size calculations were conducted for the primary objective solely, considering cognitive decline at hospital discharge. Assessment of long-term cognitive outcomes (up to 6 months) together with assessment of our secondary outcomes has been set up in an exploratory setting. The data of this study will be important to calculate the power and feasibility of a subsequent prospective project focused on long-term outcomes.