MRI IN THE EVALUATION OF LATE BONE-MARROW CHANGES FOLLOWING BONE-MARROW TRANSPLANTATION

Measurements of MR spin-lattice (T-1), and spin-spin (T-2) relaxation times in lumbar vertebrae have been performed in a pilot study on six adult patients, treated for acute myeloid leukaemia (AML). All patient s were treated with initial chemotherapy and then proceeded to bone ma rrow transplantation (BMT), conditioned with Melphalan and total body irradiation (TBI). MR measurements were made between 21 and 89 months after TBI. The relaxation times in the six patients were compared with those in six healthy age-matched volunteers to establish whether ther e were differences between the two groups. Average T-1 values in the v ertebrae of the treated patients are significantly shorter (p < 0.01) than in the healthy volunteers. This is consistent with the observatio n of a relatively hyperintense vertebral bone marrow in the T-1 weight ed images and is likely to be a consequence of treatment induced fatty replacement of marrow. Shorter T-1 values tend to be distributed with in the centre of the lumbar vertebrae compatible with observations, ma de by others, which suggest that the peripheral zone of the vertebral body has been repopulated with bone marrow cells whereas the central z one, around the basivertebral vein, is predominantly fat. Histogram di splays of vertebral body relaxation time distributions (T-1, T-2) for both patients and healthy age-matched volunteers are similar in that b oth patients and volunteers give histograms that are only slightly ske wed. This similarity is probably a reflection of the fact that the pat ients have been in remission for over a year and have generally health y bone marrow.