Prolonged bone marrow T1-relaxation in acute leukaemia. In vivo tissue characterization by magnetic resonance imaging

In vivo tissue characterization by measurement of T 1- and T 2-relaxation processes is one of the greatest potentials of magnetic resonance imaging (MRI). This may be especially useful in the evaluation of bone marrow disorders as the MRI-signal from bone marrow is not influenced by the overlying osseous tissue. Nine patients with acute leukaemia, one patient with myelodyspastic syndrome, and ten normal volunteers were included in the study. The T 1- and T 2-relaxation processes were measured in the lumbar spine bone marrow using a wholebody superconductive MR-scanner operating at 1.5 Tesla. In the patients MRI was done at the time of diagnosis and during follow-up of chemotherapy and related to bone marrow biopsies taken within three days of the MRI. At the time of diagnosis T 1-relaxation time was increased two to three times in the patients (range 0.7–3.0 sec.) compared to the controls (range 0.38–0.60 sec.). No significant difference was seen in the T 2-relaxation process. In relation to chemotherapy T 1 decreased towards the normal range in the patients who obtained complete remission, whereas T 1 remained prolonged in the patients who did not respond successfully to the treatment. The results indicate that MRI may be a non-invasive clinically useful tool in the evaluation of acute leukaemia especially as a follow-up control of chemotherapy.