¹8F-fluorodeoxyglucose positron emission tomography combined with whole-body computed tomographic angiography in critically ill patients with suspected severe sepsis with no definite diagnosis.

PURPOSE: Timely identification of septic foci is critical in patients with severe sepsis or septic shock of unknown origin. This prospective pilot study aimed to assess (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET), combined with whole-body computed tomographic angiography (CTA), in patients with suspected severe sepsis and for whom the prior diagnostic workup had been inconclusive. METHODS: Patients hospitalized in an intensive care unit with a suspected severe sepsis but no definite diagnosis after 48 h of extensive investigations were prospectively included and referred for a whole body FDG-PET/CTA. Results from FDG-PET/CTA were assessed according to the final diagnosis obtained after follow-up and additional diagnostic workup. RESULTS: Seventeen patients were prospectively included, all on mechanical ventilation and 14 under vasopressor drugs. The FDG-PET/CTA exam 1) was responsible for only one desaturation and one hypotension, both quickly reversible under treatment; 2) led to suspect 16 infectious sites among which 13 (81 %) could be confirmed by further diagnostic procedures; and 3) triggered beneficial changes in the medical management of 12 of the 17 study patients (71 %). The FDG-PET/CTA images showed a single or predominant infectious focus in two cases where CTA was negative and in three cases where CTA exhibited multiple possible foci. CONCLUSION: Whole-body FDG-PET/CTA appears to be feasible, relatively safe, and provides reliable and useful information, when prospectively planned in patients with suspected severe sepsis and for whom prior diagnostic workup had been inconclusive. The FDG-PET images are particularly helpful when CTA exhibits no or multiple possible sites.

Evidence of Cyclic Changes in the Metabolism of Abdominal Aortic Aneurysms During Growth Phases: ¹8F-FDG PET Sequential Observational Study.

UNLABELLED: The rates of growth of medically treated abdominal aortic aneurysms (AAA) are difficult to determine, and relationships with parietal inflammation and with metabolic parameters from (18)F-FDG PET remain unclear. This (18)F-FDG PET sequential observational study was aimed at analyzing the metabolic changes accompanying the growth phases of medically treated AAA. METHODS: Thirty-nine patients (37 men; age [mean ± SD], 71 ± 12 y) exhibiting small and medically treated AAA (maximal diameter, 46 ± 3 mm) underwent (18)F-FDG PET and CT angiography at baseline and 9 mo later. Clinical and imaging parameter correlates of the 9-mo increase in maximal diameter were investigated; these included (18)F-FDG maximal standardized uptake values (SUVmax) averaged for slices encompassing the AAA volume. RESULTS: Of the 39 patients, 9 (23%) had a significant (≥2.5 mm) increase in maximal diameter at 9 mo, whereas the remaining 30 did not. The patients with an increase in maximal diameter at 9 mo exhibited lower SUVmax within the AAA at baseline than patients who did not have such an increase (1.80 ± 0.45 vs. 2.21 ± 0.52; P = 0.04); they also displayed a trend toward greater changes in SUVmax at 9 mo (difference between 9 mo and baseline: +0.40 ± 0.85 vs. -0.06 ± 0.57; P = 0.07). Similar levels were ultimately reached in both groups at 9 mo (2.20 ± 0.83 and 2.15 ± 0.66). SUVmax was a significant, yet modest, baseline predictor of the absolute change in maximal diameter during follow-up (P = 0.049). CONCLUSION: The enhancement in the maximal diameter of small AAA was preceded by a stage with a low level of (18)F-FDG uptake, but this low level of uptake was no longer documented after the growth phases, suggesting a pattern of cyclic metabolic changes.