[Hematomas and MRI at 0.15 T. Apropos of 100 cases].

One hundred hematomas were examined by magnetic resonance imaging (MRI) at 0.15 T, all explored in SEpT1 and most in SEpT2. The number of cases examined in the acute phase during the first 48 hours was low: 8 cases. At this SEpT1 period the hematoma appears of elevated signal with good muscle contrast but without contrast in hepatic and cerebral parenchyma. In a weighted T2 sequence, the intense signals of cerebral edema and plasma or serum enables detection of the encephalic lesion. Findings from 68 hematomas observed in the subacute or chronic phase suggest that their appearance is pathognomonic with visualization in SEpT1 of a crown of an intense signal at least equal to that of fat. The only difficulty at this period is the discovery of a hematoma within the fat: orbital, retroperitoneal... The collection of a subdural hematoma usually appears homogeneous, the intensity of the signal varying with red cell concentration and time. In the soft tissues, the intensity of signal is a function of concentration of hemoglobin and its derivatives and of volume of serous effusion. Images of 24 hematomas during the sequelae phase confirmed the appearance of a "biochemical shell" without signal in SEpT2 and allowed detection of the hematic contents of an occupying process even after long periods, sometimes after one year.