Added value of semi-quantitative analysis of [18F]FDG PET/CT for the diagnosis of device-related infections in patients with a left ventricular assist device

Abstract

Aims: Left ventricular assist devices (LVADs) improve quality of life and survival in patients with advanced heart failure, but device-related infections (DRIs) remain cumbersome. We evaluated the diagnostic capability of [18F]FDG PET/CT, factors affecting its accuracy, and the additive value of semi-quantitative analysis for the diagnosis of DRI.

Methods and results: LVAD recipients undergoing [18F]FDG PET/CT between 2012 and 2020 for suspected DRI were retrospectively included. [18F]FDG PET/CT was performed and evaluated in accordance with EANM guidelines. The final diagnosis of DRI, based on multidisciplinary consensus and findings during surgery, whenever performed, was used as the reference for diagnosis. 41 patients were evaluated for 59 episodes of suspected DRI. The clinical evaluation established driveline infection in 32 (55%) episodes, central device infection in 6 (11%), and combined infection in 2 (4%). Visual analysis of [18F]FDG PET/CT achieved a sensitivity and specificity for driveline infections of 0.79 and 0.71, respectively, whereas semi-quantitative analysis achieved a sensitivity and specificity of 0.94 and 0.83, respectively. For central device component infection, visual analysis of [18F]FDG PET/CT achieved a sensitivity and specificity of 0.75 and 0.60, respectively. Semi-quantitative analysis using SUVratio achieved a sensitivity and specificity of 1.0 and 0.8, respectively. The increase of specificity for central component infection was statistically significant (P = 0.05).

Conclusions: [18F]FDG PET/CT reliably predicts the presence of DRI in LVAD recipients. Semi-quantitative analysis may increase the specificity of [18F]FDG PET/CT for the analysis of central device component infection and should be considered in equivocal cases after visual analysis.

Keywords: LVAD; [18F]FDG PET/CT; device-related infection; semi-quantitative analysis.

Graphical Abstract

Figure 1

[¹⁸F]FDG PET/CT (true negative both visually and by SQ analysis). This patient presented with wounds on his lower legs due to peripheral arterial insufficiency without further symptoms, but blood cultures showed Streptococcus gordonii. In absence of local symptoms and repeated negative cultures after, this positive blood culture was explained as contamination. FDG PET/CT showed no evidence of LVAD DRI. Asymptomatic increased FDG uptake at the sternum was explained as postoperative reactive uptake in a patient with impaired wound healing (complicated LVAD implantation 6 months before). 1: Subfascial driveline, 2: Suprafascial driveline, 3: Driveline exit site, 4: Outflow tract 5: Pump housing, 6: Intrathoracic part driveline. Note the increased FDG uptake at the sternum (#). Colour scales: 0–5 SUV.

Figure 2

[¹⁸F]FDG PET/CT (true positive both visually and by SQ analysis). This patient was admitted for a cardiac decompensation and elevated infection parameters in absence of fever. Patient had been treated for a Staphylococcus aureus driveline infection 2 months prior, which had initially responded well to Cefuroxime and debridement of the driveline. FDG PET/CT demonstrated advanced infection affecting the whole LVAD (earlier, only the driveline was affected). Patient underwent urgent heart transplantation and infection of the device was confirmed during surgery. 1: Subfascial driveline, 2: Suprafascial driveline, 3: Driveline exit site, 4: Outflow tract 5: Pump housing, 6: Intrathoracic part driveline. NB: Note the residual FDG uptake below the insertion of the driveline after surgical debridement and shortening of the driveline 2 months before (#). Colour scales: 0–5 SUV.

Figure 3

[¹⁸F]FDG PET/CT Driveline infection. Central device components false positive by visual analysis, true negative by SQ analysis. This patient presented with pain and discharge at driveline exit site, without further symptoms. FDFG uptake at driveline was homogenous and minimal, while central device components were FDG-avid, suspect for infection. Staphylococcus aureus was cultured from the driveline exit site and this was treated with oral antibiotics with good initial effect. Three months later, minimal surgical debridement of the driveline exist site was performed due to ongoing local irritation, still without any signs of systemic infection. A repeat [¹⁸F]FDG PET/CT 11 months after this episode showed an almost identical FDG uptake pattern around the central device component FDG uptake, confirming that this uptake was reactive. SUV ratio (liver/thorax) correctly identified this increased FDG uptake as too little to indicate infection. 1: Subfascial driveline, 2: Suprafascial driveline, 3: Driveline exit site, 4: Outflow tract 5: Pump housing, 6: Intrathoracic part driveline. NB: Note the increased FDG uptake around the driveline and the heterogeneous uptake around the pump housing and outflow tract (also visible on NAC images). Colour scales: 0–5 SUV.

Figure 4

ROC curves [¹⁸F]FDG PET/CT for infection of the LVAD driveline and central device components.

Figure 5

Proposed flowchart [¹⁸F]FDG PET/CT evaluation for DRI LVAD based on our results.