Although bone scintigraphy is not typically performed during the evaluation of suspected axSpA because of its limited diagnostic utility, there is recent data that hybrid SPECT/CT has higher sensitivity than conventional bone scintigraphy in the detection of sacroiliitis [52,53], although there is not enough evidence at this time to support its routine use for evaluating the sacroiliac joints or spine. CT Spine Area of Interest CT demonstrates structural changes in the spine that may not be apparent on radiographs [22], including structural changes such as erosions, sclerosis, bone formation, syndesmophytes, and ankyloses [49,54]. CT has been shown to demonstrate syndesmophytes with higher sensitivity than radiographs and low-dose protocols can be utilized [58]. CT is especially helpful for evaluation of the thoracic spine and facet joints, which can be challenging to evaluate on radiography [49]. Although MRI remains the technique of choice for the diagnosis of axSpA [1,3,19,22], CT can be useful in patients in the setting of prior negative radiographic and negative CT evaluation of Inflammatory Back Pain the sacroiliac joints in order to identify patients with axSpA who have disease isolated to the spine, which has been shown to occur in a variable percentage of patients based on data from MRI studies [19,59-63]. There is no role for contrast-enhanced CT in the evaluation of axSpA. Fluoride PET/CT Skull Base to Mid-Thigh There is not enough data to support the routine use of PET/CT in the evaluation of patients with suspected axSpA. F-18-fluoride has been shown to be a potentially useful tracer in identifying sites of osteoblastic activity in axSpA patients [64,65].
Inflammatory Back Pain Known or Suspected Axial Spondyloarthropathy PCAs. Although bone scintigraphy is not typically performed during the evaluation of suspected axSpA because of its limited diagnostic utility, there is recent data that hybrid SPECT/CT has higher sensitivity than conventional bone scintigraphy in the detection of sacroiliitis [52,53], although there is not enough evidence at this time to support its routine use for evaluating the sacroiliac joints or spine. CT Spine Area of Interest CT demonstrates structural changes in the spine that may not be apparent on radiographs [22], including structural changes such as erosions, sclerosis, bone formation, syndesmophytes, and ankyloses [49,54]. CT has been shown to demonstrate syndesmophytes with higher sensitivity than radiographs and low-dose protocols can be utilized [58]. CT is especially helpful for evaluation of the thoracic spine and facet joints, which can be challenging to evaluate on radiography [49]. Although MRI remains the technique of choice for the diagnosis of axSpA [1,3,19,22], CT can be useful in patients in the setting of prior negative radiographic and negative CT evaluation of Inflammatory Back Pain the sacroiliac joints in order to identify patients with axSpA who have disease isolated to the spine, which has been shown to occur in a variable percentage of patients based on data from MRI studies [19,59-63]. There is no role for contrast-enhanced CT in the evaluation of axSpA. Fluoride PET/CT Skull Base to Mid-Thigh There is not enough data to support the routine use of PET/CT in the evaluation of patients with suspected axSpA. F-18-fluoride has been shown to be a potentially useful tracer in identifying sites of osteoblastic activity in axSpA patients [64,65].