Magnetic resonance imaging in myelofibrosis and essential thrombocythaemia: contribution to differential diagnosis

To ascertain the value of magnetic resonance (MR) imaging in the differenti al diagnosis between myelofibrosis (MF) and essential thrombocythaemia (ET) , 38 patients were analysed, 20 patients had MF (idiopathic myelofibrosis, 15 cases; post-ET myelofibrosis, four cases; post-polycythaemic ME one case ) and 18 ET. Mean age was 61.5 years (range 30-89) for patients with MF and 60.9 years (range 26-83) for ET patients. MR imaging was performed in the dorsal vertebrae in all cases, and also in both femurs in 25 of the patient s. In most ET cases the MR signal of the dorsal vertebrae was not modified, whereas it was markedly reduced in MF (P = 0.0000001). With regard to femo ral marrow it was usually fatty in ET, with an absent to moderate degree of reconversion seen in the 14 cases analysed, contrasting with the marked de gree of reconversion noted in 10/11 patients with MF (P=0.000007). An inver se correlation was demonstrated between the vertebral signal and the degree of femoral reconversion. These differences were due to the fact that in ET the bone marrow adipose tissue is grossly preserved, whereas in MI: it is usually markedly decreased or absent. The above results indicate that MR imaging is a useful tool for the differe ntial diagnosis of ET and MF, with the usefulness of this technique increas ing when vertebral and femoral bone marrow studies are combined.