This is a pilot cancer imaging study investigating change in the apparent diffusion coefficient (ADC) at a single time point post-transplantation in patients. The treatment is bone marrow transplant as per standard patient care, without change for trial purposes.

Its main aim is to evaluate the engraftment of bone marrow after transplantation performing functional Magnetic Resonance Imaging (MRI) of the lumbar spine and pelvis at baseline and after 2-3 weeks after the transplantation (according to the appearances of raised white blood cells).This will enhance the understanding of bone marrow features on imaging at engraftment and improve the management of children/young adults who suffer acute leukaemia.

Following allogenic haemopoietic stem cell transplantation, changes in bone marrow apparent diffusion coefficient (ADC) are measurable at the point of engraftment and in conjunction with peripheral blood counts may provide a future biomarker of successful clinical outcome.

This is a single-center pilot study. The investigators intend to image 12 inpatients, aged 5-24 years old who are scheduled for haemopoietic stem cell transplantation.

Patients will have two MRI scans requiring them to lie in the scanner for approximately 15 minutes. Patients unable to tolerate lying flat for this length of time or to tolerate the scan for any reason will be withdrawn from the study. If required a play specialist can be organised to help the young patients feel more at ease in the MRI department. MRI does not involve radiation exposure and when performed within national safety guidelines do not pose a significant risk. Patients with contraindications to MRI such as pacemakers, certain metal implants and claustrophobia will not be recruited. Every effort will be made to book scan appointments to coincide with clinic visits.

Scans will be reported as per clinical procedures and data will be made available to the referring consultants immediately via the radiology picture archiving and communications system (PACS).

Inclusion Criteria:

1. All patients with relapsed or high risk acute lymphoblastic or myeloblastic leukaemia planned for haemopoietic stem cell transplantation
2. Cooperative paediatric individuals and young adults (5-24-years-old) not requiring general anaesthesia or sedation for the purpose of MRI
3. Able to lie flat throughout the scan

Exclusion Criteria:

1. Non cooperative patients
2. Ferromagnetic implants, contraindicating MRI
3. Claustrophobia
4. Unable to lie flat throughout the scan
5. Uncertain histological diagnosis
6. Musculoskeletal disorders
7. Metabolic disorders
8. Lack of signed parental consent and patient's verbal approval

A pilot paediatric cohort of 12 patients with Acute lymphoblastic leukaemia (ALL) or Acute myeloid leukemia (AML), aged 5-25 years old, will be studied before and after haemopoietic stem cell transplantation.

Patients with either of the two types of acute leukaemia will be included.