ARRS 2022 Abstracts

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E1411. Demystifying the Nuclear Option for Infection Imaging: A Simple and Practical Approach
Authors
  1. Samuel Speer; Oregon Health & Sciences University
  2. Erik Mittra; Oregon Health & Sciences University
  3. Gagandeep Choudhary; Oregon Health & Sciences University
  4. Bhasker Rao Koppula; University of Utah
  5. Janet Pollard; University of Iowa Hospitals and Clinics
  6. Nadine Mallak; Oregon Health & Sciences University
Background
Various nuclear medicine scans are available to help evaluate for infection; however, this remains a confusing topic, not only to trainees but also to practicing radiologists. In this exhibit, we will discuss the various radiopharmaceuticals available for infection imaging and specific indications for when each scan or a combination of scans may be preferred.

Educational Goals / Teaching Points
The goals are to discuss the various nuclear medicine scans that can be used for infection imaging, with their advantages and limitations; describe how they compare for the particular scenarios of osseous infections, cardiovascular infections, and fever of unknown origin; and finally, be able to recommend the most appropriate first test and sequencing for each scenario.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
First we will start by discussing the radiopharmaceuticals used for infection imaging, including 111-Indium-white blood cells (111In-WBC), 99m-Technetium-white blood cells (99mTc-WBC), 67-Gallium-citrate (67Ga-citrate), 99mTc-Methylene diphosphonate (99mTc-MDP) and 118F-FDG. The discussion will include their physiologic distribution, advantages and limitations, and specific indications for when each scan or a combination of scans may be preferred. This is followed by a discussion of the specific scenarios of osseous and cardiovascular infections. The options available for imaging of osseous infections include the three-phase bone scan, which is highly sensitive but lacks specificity; the combination of bone marrow imaging (with 99mTc-sulfur colloid), white blood cell imaging (with 111In-WBC), and potential addition of 99mTc-MDP bone scan, which offers a higher specificity; the combination of 67Ga-citrate and 99mTc-MDP particularly for discitis/osteomyelitis; and finally, 18F-FDG PET/CT, which has a high sensitivity but lacks specificity. Imaging options for cardiovascular infections (including endocarditis, cardiac implantable electronic device, and vascular graft infection) include 111In/99mTc-WBC scans and 18F-FDG PET/CT, each of which have advantages and limitations for this indication. Finally, we will discuss the role of nuclear medicine imaging in the evaluation of infection follow up post-treatment, fever of unknown origin, and in acute versus chronic infections.

Conclusion
To conclude, we will provide structured algorithms to help guide the decision on the most appropriate first test and sequencing of tests for each scenario.