Características fenotípicas de aislados de Colletotrichum y morfometría de

Patient recruitment is one of the most important parts of any study and a recruitment plan and process was developed from the outset. Recruitment commenced once ethics approval had been granted for the study.

Patient consent forms were customised to the age and understanding of the patients and their parents/guardians (hereafter referred to as parents). These are shown in Appendix A. The parents received both the consent form and the entire study protocol. This approach was popular and encouraged some parents to become very involved in the process. The brief information given about the principles of MRI, which included tractography images, helped the parents to understand the techniques. The parents of

all the patients were required to sign a consent form prior to their child participating in the study.

The paediatric population was divided into three groups for recruitment purposes: (i) children younger than 5 years old; (ii) from 5 to 11 years old; and, (iii) older than 11 years. Those under 5 years were given verbal information about the study. Those over 5 years with no comprehension impairments were given a special consent form that was adapted to their age. Teenagers older than 11 years old were given the full information and had the chance to sign the consent form together with their parents, if they wished.

3.1.1

Developing the scanning protocol using adult controls

A control cohort of adults was recruited first to test and improve the MRI and VEP scan protocols. Adults are generally more patient when undergoing such processes than children, which was particularly important for the multi-channel VEP scans as these are time-consuming to set up. The adult cohort was mainly composed of researchers working in GOSH with normal vision. The adults were asked to undergo a visual assessment, VEP functional scan and MRI brain scan. The purpose of the study and the risks and benefits of the tests were explained to all of the subjects. Different MRI protocols were tested on the adult cohort to identify the optimal sequence that produced a good visualisation of the optic radiations in the shortest time.

3.1.2

Scanning procedures for children

Several changes were introduced before scanning commenced in children. The MRI protocols were altered to reduce the scanning time while still attaining high quality images. This is likely to have greatly increased the number of successful scans performed by this study because undergoing tests is stressful for many children and some cannot tolerate even the clinical imaging needed for their own treatment or diagnosis. Much effort was targeted towards reducing the impact of the test, by making the test environment friendlier, interacting with the children and explaining what would happen beforehand. The ‘clinical’ environment of the hospital was minimised by having a parent in the scanner room and by the playing a film or cartoon for older children.

Ethics approval was granted by the ethics committee to scan children of all ages. For patients with ophthalmological diseases, the research scan was similar to the clinical scan. Since children do not generally like being confined to restricted environments such as an MRI machine, where movement and activity is restricted, different approaches were used to scan children of different ages.

Babies younger than one year of age are very tolerant of different environments. MRI scans were performed using the feed and wrap technique. This involves feeding the baby just minutes prior to scanning, after which it tends to fall into a deep sleep. A quiet room next to the scan was adapted for feeding, with mild lighting and soft music on request. After feeding, the baby was wrapped and ear plugs were inserted to protect the baby’s ears.

Most children between 1 and 5 years of age required sedation to carry out the imaging. A few, mainly girls, were collaborative without the need for any medication. The children attended an appointment in the clinical MRI slot for sedation and DTI scans were added at the end of the test if there was sufficient time. The children were fasted by protocol up to a maximum of 4 hours before arrival, then a small dose of sedative was given by weight, following the protocol of the Department of Anaesthesia at GOSH. If the child failed to sleep or if they woke up in the middle of the clinical imaging acquisition and moved, the DTI scan was not attempted or abandoned. Children older than 5 years of age did not require sedation for the study. Some children could not tolerate the scanning time so it was not possible to obtain DTI scans. The most difficult cohort to scan were males aged 4 to 5.5 years. Females tended to adapt better and were more cooperative than males, which is probably due to different behavioural development and better adaptation to unfamiliar environments.

Around 200 subjects were scanned in this study in total, covering a range of ophthalmologic and other diseases. Only a subset of these are examined in this thesis. Around 6 hours was required on average to recruit each patient, gain consent and perform the scans.