How to combine CTA, 99mTc-WBC SPECT/CT, and [18F]FDG PET/CT in patients with suspected abdominal vascular endograft infections?

Chiara Lauri; Giuseppe Campagna; Francesco Aloisi; Alessandro Posa; Roberto Iezzi; Pasqualino Sirignano; Maurizio Taurino; Alberto Signore

doi:10.1007/s00259-023-06309-x

How to combine CTA, ^99mTc-WBC SPECT/CT, and [¹⁸F]FDG PET/CT in patients with suspected abdominal vascular endograft infections?

Eur J Nucl Med Mol Imaging. 2023 Sep;50(11):3235-3250. doi: 10.1007/s00259-023-06309-x. Epub 2023 Jun 27.

Authors

Chiara Lauri¹, Giuseppe Campagna², Francesco Aloisi³, Alessandro Posa⁴, Roberto Iezzi^{4

5

6}, Pasqualino Sirignano⁷, Maurizio Taurino³, Alberto Signore²

Affiliations

¹ Nuclear Medicine Unit, Department of Medical-Surgical Sciences and of Translational Medicine, Sant'Andrea Hospital, "Sapienza" University of Rome, 00161, Rome, Italy. chiara.lauri@uniroma1.it.
² Nuclear Medicine Unit, Department of Medical-Surgical Sciences and of Translational Medicine, Sant'Andrea Hospital, "Sapienza" University of Rome, 00161, Rome, Italy.
³ Vascular Surgery Unit, Department of Clinical and Molecular Medicine, Sant'Andrea Hospital, "Sapienza" University of Rome, 00161, Rome, Italy.
⁴ Dipartimento Di Diagnostica Per Immagini, Radioterapia Oncologica ed Ematologia - Fondazione Policlinico Universitario A Gemelli IRCCS, Rome, Italy.
⁵ Diagnostic and Interventional Radiology Unit, Gemelli Molise Hospital, Campobasso, Italy.
⁶ Università Cattolica del Sacro Cuore, Rome, Italy.
⁷ Vascular Surgery Unit, Sant'Andrea Hospital, Department of General and Specialistic Surgery, Sapienza" University of Rome, 00161, Rome, Italy.

Abstract

Purpose: We aimed at comparing ^99mTc-HMPAO white blood cells (^99mTc-WBC) scintigraphy, 18fluorine-fluorodeoxyglucose ([¹⁸F]FDG) positron emission tomography/computed tomography (PET/CT) and CT angiography (CTA) in patients with suspected abdominal vascular graft or endograft infection (VGEI). Moreover, we attempted to define a new visual score for interpreting [¹⁸F]FDG PET/CT scans aiming at increasing its specificity.

Methods: We prospectively compared ^99mTc-WBC SPECT/CT, [¹⁸F]FDG PET/CT, and CTA in 26 patients with suspected abdominal VGEI. WBC scans were performed and interpreted according to EANM recommendations. [¹⁸F]FDG PET/CT studies were assessed with both qualitative (Sah's scale and new visual score) and semi-quantitative analyses. CTA images were interpreted according to MAGIC criteria. Microbiology, histopathology or a clinical follow-up of at least 24 months were used to achieve final diagnosis.

Results: Eleven out of 26 patients were infected. [¹⁸F]FDG PET/CT showed 100% sensitivity and NPV, with both scoring systems, thus representing an efficient tool to rule out the infection. The use of a more detailed scoring system provided statistically higher specificity compared to the previous Sah's scale (p = 0.049). ^99mTc-WBC SPECT/CT provided statistically higher specificity and PPV than [¹⁸F]FDG PET/CT, regardless the interpretation criteria used and it can be, therefore, used in early post-surgical phases or to confirm or rule out a PET/CT finding.

Conclusions: After CTA, patients with suspected late VGEI should perform a [¹⁸F]FDG PET/CT given its high sensitivity and NPV. However, given its lower specificity, positive results should be confirmed with ^99mTc-WBC scintigraphy. The use of a more detailed scoring system reduces the number of ^99mTc-WBC scans needed after [¹⁸F]FDG PET/CT. Nevertheless, in suspected infections within 4 months from surgery, ^99mTc-WBC SPECT/CT should be performed as second exam, due to its high accuracy in differentiating sterile inflammation from infection.

Keywords: CT angiography; Vascular endograft infection; WBC scintigraphy; [18F]FDG PET/CT.

MeSH terms

Fluorodeoxyglucose F18*
Humans
Leukocytes
Positron Emission Tomography Computed Tomography*
Positron-Emission Tomography
Radiopharmaceuticals
Sensitivity and Specificity
Single Photon Emission Computed Tomography Computed Tomography
Technetium Tc 99m Exametazime

Substances

Fluorodeoxyglucose F18
Technetium Tc 99m Exametazime
Radiopharmaceuticals