The accuracy of low field strength (0.08 Tesla) magnetic resonance imaging (MRI) of bone marrow for the detection of acute leukaemia in adults has been assessed by comparison with bone marrow biopsy results. Spin lattice relaxation time (T,) measurements from patients were compared with those from 90 volunteers. Eighteen patients were studied at the time of diagnosis of leukaemia. Bone marrow T, was prolonged in all cases. One of two patients with refractory anaemia with excess of blasts in transformation (RAEBt) had prolonged bone marrow T,, the other had normal T,. T, at the time of diagnosis for patients with acute leukaemia or RAEBt correlated with thecellularity and blast cell count in the marrow. None of the 17 patients who were studied when in long-term remission of leukaemia had prolonged marrow TI.
Serial studies were undertaken in five of the newly diagnosed patients. An increase in bone marrow T, was observed in each of four patients studied seven days after the start of treatment, at a time when they showed a decrease in leukaemic cells on peripheral blood examination. T, measurements made 3 weeks after the commencement of chemotherapy were similar to pretreatment values and did not reflect the reduction in leukaemic infiltration observed on bone marrow needle aspirate. The implications and possible explanations for these findings are discussed.