Abstract
18F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) is a promising new tool for the identification of inflammatory, infectious, and neoplastic foci. The aim of our work was to evaluate the diagnostic value of FDG-PET/CT in patients treated on a neurological/neurosurgical ICU or stroke unit. We performed a single-center, 10-year, retrospective evaluation of the value of FDG-PET/CT in critically ill adult patients with severe neurological disease. 42 patients underwent FDG-PET/CT. Of these, 15 were ventilated and 10 were under vasopressor support. We identified four indications for performing FDG-PET/CT: (1) excluding a paraneoplastic etiology in an otherwise unexplained encephalitis, encephalopathy or neuropathy, (2) detecting a large-vessel vasculitis in patients with ischemic stroke, (3) detecting an infectious focus in sepsis, and less frequently (4) evaluating cerebral metabolism. In 22 patients who were evaluated for an unknown malignancy, 5 scans revealed either a previously unknown tumor or unknown metastases of a previously treated malignancy. Of 11 patients investigated for large-vessel vasculitis, 2 showed an inflammation of arteries supplying the brain. Of six sepsis cases, FDG-PET/CT identified an infectious focus in four. We found FDG-PET/CT to be a helpful tool in critically ill neurological patients. The results of the FDG-PET/CT had direct therapeutic consequences in the 12 true-positive cases. In 24 of the 29 negative cases, FDG-PET/CT helped exclude alternative diagnoses and/or influenced therapy. Our findings demonstrate the feasibility and diagnostic benefit of FDG-PET/CT in this group of patients.
Highlights
In recent years, 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) has become a recognized and well-researched imaging modality for the evaluation of neoplastic, inflammatory, and infectious disorders [1]
42 FDG-PET/computed tomography (CT) scans were performed on critically ill adult patients: 26 were referred from the neurological ICU, three from the neurosurgical ICU, and 13 from the stroke unit
With suspected malignancy With suspected vasculitis With suspected infectious focus Mean time in ICU Median interval between ICU admission and PET/CT Patients ventilated at time of scan Patients on vasopressor support at time of scan Mortality rate Admission diagnosis Ischemic stroke Subarachnoid hemorrhage Encephalitis/meningitis Encephalopathy Seizures Neuropathy Infection of unknown origin
Summary
18F-fluorodeoxyglucose positron emission tomography (FDG-PET) has become a recognized and well-researched imaging modality for the evaluation of neoplastic, inflammatory, and infectious disorders [1]. Increased FDG uptake indicates increased intracellular glucose metabolism. FDG may accumulate in malignant cells as well as in cells involved in inflammatory and infectious processes, such as macrophages. PET technology has been combined with computed tomography (CT) scanning in a single device. Hybrid imaging by FDG-PET/CT offers considerable advantages over regular CT by providing anatomical information in addition to detecting areas with increased metabolism. Several studies have documented the important role of FDG-PET/CT in detecting unknown malignancies [2], detecting large-vessel vasculitis, [3] and diagnosing patients with fever of unknown origin [4]
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