This study was approved by the National Research Ethics Service (NRES) committee London – West London and was conducted in accordance with the revised declaration of Helsinki (2000), the International Committee on Harmonisation Good Clinical Practice (GCP) guidelines and National Health Service (NHS) Research Governance Framework. Imperial College London sponsored the research which was conducted under a Home Office license for research with schedule 1 drugs. The Medicines and Healthcare products Regulatory Agency (MHRA) approved the study. All patients gave written informed consent, consistent with GCP.
Imaging vs clinical outcomes
To explore relationships between significant imaging outcomes and the main clinical outcomes, we chose to focus on changes in depressive symptoms from: 1) pre-Treatment to scan 2 (i.e. one-day post-treatment), and 2) pre-Treatment to 5 weeks post-Treatment. The primary clinical outcome measure, the 16-item Quick Inventory of Depressive Symptoms (QIDS-SR16) was chosen for this purpose. Relationships between imaging outcomes and contemporaneous decreases in depressive symptoms were calculated using a standard Pearson’s r, and relationships with the longer-term (i.e. at 5 weeks post-treatment) changes in depressive symptoms were calculated by splitting the sample into responders (>50% reduction in QIDS-SR16 scores) and non-responders at this time-point, and then performing a one-tailed t-test on the relevant imaging outcomes (one-tailed as directionality was unequivocally implied by the direction of the significant imaging outcome). We used a revised version of the QIDS-SR16 for 24-hour measurement for the post-treatment scan in order to get a contemporaneous, state-related index of depressive symptoms at this time-point.
Imaging was performed on a 3 T Siemens Tim Trio using a 12-channel head coil at Imanova, London, UK. Anatomical images were acquired using the ADNI-GO (Alzheimer’s Disease Neuroimaging Initiative, Grand Opportunity52) recommended MPRAGE parameters (1 mm isotropic voxels, TR = 2300 ms, TE = 2.98 ms, 160 sagittal slices, 256 × 256 in-plane FOV, flip angle = 9 degrees, bandwidth = 240 Hz/pixel, GRAPPA acceleration = 2).