PEIR Digital Library

Welcome to the Pathology Education Informational Resource (PEIR) Digital Library, a multidisciplinary public access image database for use in medical education.

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RADIOLOGY: MUSCULOSKELETAL: Case# 33665: STRESS INJURY TO THE PARS INTERARTICULARIS. A 16 year old shortstop presented with a recent history of low back pain. X-rays of the lumbar spine were unremarkable. A bone scan obtained later demonstrated significant osseous remodeling with planar imaging in the L4-L5 region and SPECT localized the increased activity to the pars interarticularis. This patient discontinued athletic activity for 3 months with complete clinical recovery. A repeat SPECT at that time (not shown here), revealed resolution of the prior abnormalites seen at L5. SPECT (single photon emission computed tomography) imaging offers superior contrast resolution in exchange for a slight loss in spatial resolution. The loss in spatial resolution results from the increased distance between the camera and the patient. The superior contrast resolution of SPECT is especially helpful in discerning activity emanating from small structures surrounded by overlapping tissues. Patient Prep: None

Peter Anderson