Variant 2: Suspected septic arthritis or soft tissue infection. Initial radiographs normal or with findings suggestive of joint effusion or soft tissue swelling. Next imaging study. For septic arthritis, the body regions covered are ankle, elbow, hip, knee, shoulder, wrist. For soft tissue infection, the body regions covered are abdomen, neck, ankle, chest, elbow, thigh, foot, forearm, hand, hip, arm, knee, pelvis, shoulder, leg, wrist. 3-Phase Bone Scan Area of Interest Radionuclide imaging, which includes 3-phase bone scan, is of limited use for the diagnosis of septic arthritis and soft tissue infection [7]. On 3-phase bone scans, early images may show increased activity with hyperperfusion and hyperemia on flow and blood pool phases. Delayed images may be normal or have increased activity limited to the articular surfaces, in the case of a septic joint [7]. Compared with US, CT, and MRI, bone scan has poor spatial resolution and lacks specificity [4]. However, bone scan can be useful for the evaluation of multifocal infections. Image-Guided Aspiration Area of Interest In many cases, imaging cannot distinguish infected from noninfected joints or fluid collections, and aspiration and culture are needed for diagnosis [8,9]. Culture allows for identification of the infectious organism, which directly affects treatment. Although imaging may delay performing the aspiration, preaspiration imaging with US, CT, or MRI can be essential for planning for a safe aspiration [8]. Image-guided aspiration is ideal because proper, accurate needle placement is confirmed with fluoroscopy, US, CT, and rarely MRI. Also, image guidance significantly reduces vascular complications and injury to nerves. Using image guidance, needle trajectory and placement can be planned to reduce the risk of contaminating normal adjacent tissues [10].
Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. Variant 2: Suspected septic arthritis or soft tissue infection. Initial radiographs normal or with findings suggestive of joint effusion or soft tissue swelling. Next imaging study. For septic arthritis, the body regions covered are ankle, elbow, hip, knee, shoulder, wrist. For soft tissue infection, the body regions covered are abdomen, neck, ankle, chest, elbow, thigh, foot, forearm, hand, hip, arm, knee, pelvis, shoulder, leg, wrist. 3-Phase Bone Scan Area of Interest Radionuclide imaging, which includes 3-phase bone scan, is of limited use for the diagnosis of septic arthritis and soft tissue infection [7]. On 3-phase bone scans, early images may show increased activity with hyperperfusion and hyperemia on flow and blood pool phases. Delayed images may be normal or have increased activity limited to the articular surfaces, in the case of a septic joint [7]. Compared with US, CT, and MRI, bone scan has poor spatial resolution and lacks specificity [4]. However, bone scan can be useful for the evaluation of multifocal infections. Image-Guided Aspiration Area of Interest In many cases, imaging cannot distinguish infected from noninfected joints or fluid collections, and aspiration and culture are needed for diagnosis [8,9]. Culture allows for identification of the infectious organism, which directly affects treatment. Although imaging may delay performing the aspiration, preaspiration imaging with US, CT, or MRI can be essential for planning for a safe aspiration [8]. Image-guided aspiration is ideal because proper, accurate needle placement is confirmed with fluoroscopy, US, CT, and rarely MRI. Also, image guidance significantly reduces vascular complications and injury to nerves. Using image guidance, needle trajectory and placement can be planned to reduce the risk of contaminating normal adjacent tissues [10].