Quels sont les signes indirects de sepsis sévère en tomoscintigraphie par émission de positons au 18-désoxy-fluoroglucose ?

Abstract

Introduction18F-fluorodeoxy-fluoroglucose (FDG) is generally actively trapped by infectious foci and thereby, the positron emission tomography (PET) imaging of FDG is increasingly used for detecting and localizing infectious foci. Indirect signs of infection were also described at FDG-PET but up to now, they were poorly analyzed and assessed. This study aimed to identify indirect signs of sepsis on the FDG-PET images from patients with severe sepsis and to assess their diagnostic values. Materials and methodsWe analyzed the FDG-PET images of 13 patients aged from 22 to 82 years and for whom a final diagnostic of severe sepsis could be achieved (7 pneumonia, 2 osteitis, 1 cervical cellulitis, 1 pyelonephritis, 1 abdominal parietal abscess, 1 abscess of an abdominal aortic stent-graft). All were mechanically ventilated and 7 had vasopressive drugs (septic shock). These FDG-PET images were compared to those from a group of control subjects matched for age and sex. Regions of interest were used to quantify the maximal standardised uptake value (SUVmax) within different tissues and organs. ResultsCompared to control-group, the sepsis-group exhibited higher SUVmax for bone marrow (3.73±1.14 versus 2.25±0.57, P<0.001), spleen (3.06±0.71 versus 2.15±0.46, P=0.001), adrenal glands (2.64±1.00 versus 1.77±0.35, P=0.016). At the opposite, SUVmax was lower in sepsis-group than in control-group for myocardium (3.44±1.20 versus 8.00±3.61, P=0.001). No significant difference was documented for liver, thyroid, skeletal muscles, arteries and blood. A cut-off of 2.6 for the SUVmax of bone marrow provided a sensitivity of 85% and a specificity of 92% for differentiating the septic patients from controls. ConclusionSeveral indirect signs of severe sepsis may be documented at FDG-PET: the hypermetabolisms of spleen and of bone marrow, which are conventional signs of infectious diseases, but also a myocardial hypometabolism and an adrenal hypermetabolism, which might rather relate to the severity of these diseases and to cardiovascular involvements.