In critically ill patients with sepsis, identifying the infectious source can be challenging despite microbiology, ultrasound, and conventional cross-sectional imaging. The study evaluated the role of FDG PET/CT (18F-fluorodeoxyglucose positron emission tomography combined with CT) when the infectious focus remained unresolved after standard diagnostic workup.
The investigators aimed to assess the diagnostic yield of FDG PET/CT in selected ICU patients with unresolved infection, to describe the infectious foci detected, and to document diagnostic and therapeutic actions that followed imaging.
This was a retrospective single-center cohort study conducted at a tertiary university hospital. The analysis included 108 FDG PET/CT scans performed in 103 adult patients treated in the hospital's intensive care units. PET/CT referrals were selective and made for clinical problem-solving rather than routine use.
Cases included adult ICU patients with sepsis in whom the infectious focus remained unclear after available diagnostics. PET/CT was requested for two principal indications: to search for an unknown infectious focus or to confirm or exclude a suspected focus. Details on explicit inclusion or exclusion criteria beyond these referral reasons were not reported in the abstract.
Primary measures reported were PET/CT findings suspicious for infection and confirmation of those findings according to a composite clinical reference standard. The study classified scans as clinically informative or not, calculated diagnostic performance metrics (sensitivity, specificity, positive and negative predictive values with 95% CIs), and recorded subsequent diagnostic or therapeutic actions following imaging.
Across 108 scans, FDG PET/CT detected an infectious focus that was subsequently confirmed in 72 scans (66.7%). Eight additional PET/CT findings suspicious for infection were not confirmed. One scan was classified as false negative.
Apparent diagnostic performance reported in the source was: sensitivity 98.6% (95% CI, 96.0–100.0%), specificity 77.1% (95% CI, 63.2–91.1%), positive predictive value 90.0% (95% CI, 83.4–96.6%), and negative predictive value 96.4% (95% CI, 89.6–100.0%).
When used specifically to search for an unknown focus, PET/CT subsequently identified at least one confirmed infectious site in 53 of 81 scans (65.4%). When used to confirm or exclude a suspected focus, results were diagnostically conclusive in 24 of 27 scans (88.9%). Overall, 77 of 108 scans (71.3%) were judged clinically informative.
Findings on PET/CT prompted further clinical actions. After imaging, additional noninvasive diagnostics were performed following 50 scans. Invasive diagnostic or therapeutic procedures were undertaken after 52 scans. Antimicrobial regimens were modified after 44 scans. The abstract reports these downstream actions but does not detail the specific types of invasive procedures, the nature of antimicrobial changes, or the timing relative to imaging.
The authors interpret the results to indicate that in selected critically ill patients with sepsis and unresolved infection, FDG PET/CT frequently identified a confirmed infectious focus or helped reduce diagnostic uncertainty. They advocate for FDG PET/CT as a complementary, problem-oriented diagnostic tool rather than as routine imaging in ICU sepsis.
Important limitations noted in the source include selective referral bias, the retrospective study design, and an imperfect composite clinical reference standard used to confirm PET/CT findings. Because of these limitations, the reported diagnostic performance estimates should be interpreted cautiously. The authors call for prospective studies to better define patient selection criteria and to determine whether PET/CT improves patient-centered outcomes.
In this retrospective cohort of 108 scans in ICU patients with unresolved sepsis, FDG PET/CT demonstrated a high apparent sensitivity and a substantial rate of clinically informative results. Imaging commonly led to further diagnostics, invasive procedures, or changes to antimicrobial therapy. The study supports selective, problem-oriented use of PET/CT in this population but emphasizes the need for prospective research to validate these findings and link imaging to outcomes.