Fever of unknown origin, infection of subcutaneous devices, brain abscesses and endocarditis

Abstract

The term 'fever of unknown origin' includes a wide range of conditions that often remain undiagnosed. The possibility of an infection must be promptly diagnosed in order to begin appropriate therapy. Imaging with radiopharmaceuticals, computed tomography, magnetic resonance imaging and ultrasound are the most commonly applied techniques, usually performed in addition to blood tests, biopsies or tissue cultures when required. The lack of comparative studies investigating the accuracy of each radiopharmaceutical for the study of fever of unknown origin was the incentive to perform a meta-analysis of peer articles published between 1981 and 2004 (33 papers) describing the use of nuclear medicine imaging for this purpose. Furthermore, infection of subcutaneous devices, brain abscesses and endocarditis must be considered amongst the causes of fevers of unknown origin. Reviews of 23, 10 and 10 papers, respectively (from 1976 to 2005), were performed on these specific topics. The results may be a useful guide for the choice of the optimal radiopharmaceutical(s) and diagnostic strategy to be applied in each clinical condition and for different aims.

Receptor Binding Ligands to Image Infection

“…The gold standard for imaging infection is radiolabeled white blood cells [89][90][91][92]. For reason of safety, simplicity and cost, it would be desirable to have a receptor specific ligand that could be used for imaging infection and that could allow the differential diagnosis between sterile and septic inflammatory processes.…”

Current Status of Molecular Imaging in Infections

“…A meta-analysis of the literature from 1976 to 2005, (12 articles, referring to 378 patients, 380 lesions) defines 99m Tc-labeled anti-granulocyte mAbs alone or in association with echocardiography the most accurate procedure for the detection of infective endocarditis (sensitivity = 100%, specificity = 86% and accuracy = 92% with 89% positive predictive value) [168]. The real breakthrough for nuclear medicine procedure in IE and device related infection has reached with the introduction of SPECT/CT and PET/CT equipment: an exhaustive evaluation of the heart region is impossible without the possibility to acquire 3D images of the thorax.…”

Nuklearmedizinische Entzündungsdiagnostik: Update 2017

“…Bei granulozytär schwach floriden entzündlichen Prozessen wird sowohl für 99m Tc-Leukozyten als auch AgAk die Verlängerung der Untersuchungsdauer auf 24 Stunden und neben der visuellen auch eine semiquantitative Auswertung mittels Regions-of-interest-Technik empfohlen [37]. [21]. Die ätiologische Heterogenität des Krankheitsbilds FUO bedingt zwangsläufig, dass der undifferenzierte Einsatz von in vitro oder in vivo markierten Leukozyten nur bei etwa einem Drittel der Patienten, nämlich bei denen mit einer infektiösen Erkrankung, eine rationelle Diagnosefindung ermöglicht.…”

“…78 %. Im Vergleich dazu zeigte die FDG-PET eine gleichwertige diagnostische Genauigkeit von 77 %, die aus einer höheren Sensitivität von 78 % aber geringeren Spezifität von 59 % resultiert [21].…”