Regression of Myelofibrosis and Osteosclerosis following Hematopoietic Cell Transplantation Assessed by Magnetic Resonance Imaging and Histologic Grading

Myelofibrosis is a reactive, often inhomogeneous process in the marrow cavity, and sampling errors on biopsies obtained to diagnose and monitor the course of myelofibrosis have been a constant problem in hematopathology. We investigated the potential utility of magnetic resonance imaging (MRI) of the lumbar spine, pelvis, and femora as a diagnostic and monitoring technique for assessment of myelofibrosis. Findings on serial marrow biopsies were correlated with T1-weighted spin-echo and short inversion time inversion recovery (STIR) images in patients with chronic idiopathic myelofibrosis or myelofibrosis developing from polycythemia vera or essential thrombocythemia who underwent hematopoietic cell transplantation (HCT). Thirty-five patients were studied before HCT; 11 were followed for 3 months and 10 patients for >/=1 year after HCT with sequential marrow biopsies and MRI studies. MRI allowed direct visualization of the biopsy sites and correlation of histologic and MRI findings. MRI also provided assessment of the extent and degree of myelofibrosis in a large volume of the skeletal marrow. There was good correlation between biopsy results and MRI findings at specific biopsy sites and between successful HCT and resolution of fibrosis and osteosclerosis as determined by MRI. We conclude that in patients with myelofibrosis, MRI of the skeleton provides a comprehensive assessment of the pattern and extent of fibrosis and allows for correlation with biopsy findings. In patients undergoing HCT, MRI accurately reflects response or progression of marrow disease.