An NMR image of a patient's heart uses SSFSE (single shot fast spin echo) type pulses to condition the body by a preparation of a phase-encoding gradient pulse whose duration differs from one sequence to another so as to define, from one sequence to another, a different effective echo time. At each sequence an image is displayed representing the discrimination of the contributions of the particles of the body as a function of their time T2 compared with this effective time. For the heart, with a single respiration on the part of the patient, lesions due to infarction and transplant rejection are revealed.