Imaging of Musculoskeletal Infections: Value of Planar & SPECT/CT Imaging.

Objectives: 1. To describe the value of planar gamma imaging and SPECT/CT in diagnosing musculoskeletal infections 2. To describe the clinical context and value of various nuclear medicine radiopharmaceuticals in investigating musculoskeletal infections 3. To illustrate the clinical value with imaging and patient outcomes.

Methods: Review of nuclear medicine and SPECT/CT clinical case database (n > 500) for musculoskeletal infection / inflammation imaging at a tertiary care institution and literature review.

Results: Commonly used radiopharmaceuticals in evaluating musculoskeletal infections include ¹¹¹In or ^99mTc labeled WBCs, ^99mTc-diphosphonate, ^99mTc-labelled antigranulocyte antibodies, ¹⁸F-FDG, and Ga-67 citrate. The use of complementary bone marrow imaging, most commonly with 99mTc sulfur colloid in combination with ¹¹¹In or ^99mTc labeled WBCs, is routinely used to differentiate infection from trauma or post-surgical bone marrow turnover. While the accuracy of combined bone marrow imaging is approximately 95%, planar images do not provide information about the depth or anatomic location of infection. The combination of radionuclide imaging using SPECT/CT greatly improves the specificity of detecting MSK infections particularly in equivocal cases while simultaneously providing anatomic information (skeletal versus soft tissue), which may help guide clinical therapy. When used in combination with SPECT/CT, the sensitivity remains at 78% but the specificity increases to 86%. Combination with data from either CT/x-ray/or MRI, the sensitivity of SPECT/CT increases to 100% for detecting osteomyelitis.

Conclusion: Planar and SPECT/CT imaging with various radiopharmaceuticals are valuable to diagnose musculoskeletal infection and impact patient outcomes.