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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
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Least helpful for the diagnosis of spondylolisthesis -
assistant
The correct answer is  All the given radiological investigations are used for spondylolisthesis. However, AP x-ray of spine is least helpful as in low grades of spondylolisthesis it may be normal.
On the other hand lateral x-ray, CT and MRI (sagittal view) diagnose even the mildest degree of spondylolisthesis.
It is worth noting that spondylolysis (not spondylolisthesis) may be missed on lateral x-ray and MRI. CT scanning is more sensitive in diagnosing spondylolysis.