Clinical implications of increased uptake in bone marrow and spleen on FDG-PET in patients with bacteremia

Jordy P Pijl,Derya Yakar,Riemer H J A Slart,Andor W J M Glaudemans,Marjan Wouthuyzen-Bakker,Thomas C Kwee

doi:10.1007/s00259-020-05071-8

Abstract

PurposeTo investigate which clinical factors and laboratory values are associated with high FDG uptake in the bone marrow and spleen on 2-deoxy-2-[18F]fluoro-d-glucose (FDG) positron emission tomography (PET)/computed tomography (CT) in patients with bacteremia.MethodsOne hundred forty-five consecutive retrospective patients with bacteremia who underwent FDG-PET/CT between 2010 and 2017 were included. Mean standard uptake values (SUVmean) of FDG in bone marrow, liver, and spleen were measured. Bone marrow-to-liver SUV ratios (BLR) and spleen-to-liver SUV ratios (SLR) were calculated. Linear regression analyses were performed to examine the association of BLR and SLR with age, gender, hemoglobin, leukocyte count, platelets, glucose level, C-reactive protein (CRP), microorganism, days of antibiotic treatment before FDG-PET/CT, infection focus, use of immunosuppressive drugs, duration of hospital stay (after FDG-PET/CT), ICU admission, and mortality.ResultsC-reactive protein (p = 0.006), a cardiovascular or musculoskeletal focus of infection (p = 0.000 for both), and bacteremia caused by Gram-negative bacteria (p = 0.002) were independently and positively associated with BLR, while age (p = 0.000) and glucose level before FDG-PET/CT (p = 0.004) were independently and negatively associated with BLR.For SLR, CRP (p = 0.001) and a cardiovascular focus of infection (p = 0.020) were independently and positively associated with SLR, while age (p = 0.002) and glucose level before FDG-PET/CT (p = 0.016) were independently and negatively associated with SLR.ConclusionHigh FDG uptake in the bone marrow is associated with a higher inflammatory response and younger age in patients with bacteremia. In patients with high FDG uptake in the bone marrow, a cardiovascular or musculoskeletal focus of infection is more likely than other foci, and the infection is more often caused by Gram-negative species. High splenic FDG uptake is associated with a higher inflammatory response as well, and a cardiovascular focus of infection is also more likely in case of high splenic FDG uptake.

Highlights

Infection is one of the most common reasons for hospital admission [1]
High FDG uptake in the bone marrow is associated with a higher inflammatory response and younger age in patients with bacteremia
In patients with high FDG uptake in the bone marrow, a cardiovascular or musculoskeletal focus of infection is more likely than other foci, and the infection is more often caused by Gram-negative species

Summary

Introduction

Infection is one of the most common reasons for hospital admission [1]. In patients with systemic signs of infection such as fever, blood cultures may be obtained to assess whether bacteria crossed anatomic barriers of the body and entered the bloodstream, causing bacteremia [2, 3]. Eur J Nucl Med Mol Imaging (2021) 48:1467–1477 glucose, infection sites are often readily visible on FDG-PET/ CT, even before anatomical changes (such as abscess formation) have occurred [6]. In some patients undergoing FDG-PET/CT for detecting the focus of infection, markedly increased FDG uptake is seen in the bone marrow or spleen. Hypermetabolism of the bone marrow or spleen has been associated with laboratory values such as C-reactive protein or hemoglobin and even prognosis in patients with several types of cancer [9,10,11,12,13,14] and autoimmune disease [15, 16]. In a study by Boursier et al, high FDG uptake of the bone marrow and spleen was independently associated with endocarditis [17]

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Discussion

Conclusion