MRI of the knee region in leukemic children. Part I. Initial pattern in patients with untreated disease.

The results of MRI studies performed on the medullary cavity in the knee region of 15 children with leukemia and 5 healthy children are reported. By the age of a few years the signal intensities and the relaxation times of bone marrow begin to resemble fat. Early leukemic infiltration can therefore be more easily recognised in the knee region than in the spine using simple T1 weighted Spin-Echo images. We observed an abnormal signal pattern in all our patients which fell into three groups: (a) diffuse uniform (b) diffuse non-uniform and (c) patchy. We have not been able to correlate these into age, sex or the risk factor determined by clinical or laboratory methods. The diffuse patterns seem to dominate in cases of ALL, the patchy forms in AML. No correlation could be found between the blast levels established by the iliac crest biopsy and the results of MRI.