What imaging modalities should be used if negative plain films are found in cases of lumbosacral pars interarticularis stress fractures?

In cases where negative plain films are identified yet there's a high suspicion of lumbosacral pars interarticularis stress fractures, using a bone scan with SPECT (Single Photon Emission Computed Tomography) and CT (Computed Tomography) scan is crucial. Stress fractures, especially in the pars interarticularis region, may not be visible on initial X-ray imaging because they often have not yet progressed to the point of causing visible bony changes.

A bone scan can detect increased osteoblastic activity associated with the stress response even before structural changes appear on X-rays. The addition of SPECT enhances the specificity by localizing the increased blood flow and metabolic activity more accurately to the fracture site. Meanwhile, a CT scan offers detailed imaging that can show the fracture in the context of the bony anatomy and help diagnose subtle fractures that may be missed on other imaging modalities.

Therefore, the combination of a bone scan with SPECT and a CT scan is the best approach in this scenario, as it maximizes the chances of identifying the subtle changes that indicate the presence of a pars interarticularis stress fracture. Other options, such as ultrasound or relying solely on physical examination, wouldn’t provide the necessary detailed imaging to confirm or