Applications of SPECT/CT in the Evaluation of Spinal Pathology: A Review

A 70-year-old man had previously undergone L3 to L5 decompression for lumbar spinal stenosis with leg dominant radicular pain. After the decompression, the patient presented with a new complaint of axial flexion-dominant mid-lumbar pain in the absence of leg symptoms. Advanced imaging demonstrated no significant residual/recurrent stenosis on sagittal and axial T2-weighted MRI sequences (1, 2, and 3), and appropriate decompression on sagittal and axial computed tomography images without evidence of pars interarticularis fracture or subtotal facetectomy (4, 5, and 6). Single photon emission computed tomography with computed tomography findings demonstrated increased radiotracer uptake in the L3 to L4 disc (7 and 8). The L3 to L4 disc was determined to be the dominant pain generator, resulting in a discogenic pain pattern. The patient was then referred for further physical therapy and physical medicine and rehabilitation.

71-year-old woman with low back, buttock, and bilateral leg pain. Lateral (A) spine radiograph shows L4 to L5 instrumentation with prior interspinous spacer and unilateral pedicle screws with interbody device (arrow) without evidence of complications. Lumbar spine T2 sagittal magnetic resonance image (B) shows no central canal stenosis, also seen on axial (not displayed) and metal artifact at L4 to L5 (arrow) related to instrumentation. Posterior planar 99mTc-MDP bone scan (C) and axial fused single photon emission computed tomography with computed tomography (D) images show H-shaped radiotracer uptake within the sacrum, with associated sclerotic changes on computed tomography (E), compatible with sacral insufficiency fracture.

A 76-year-old woman presented with acute-onset low back pain. Anteroposterior (A) and lateral (B) spine radiographs show mild height loss at the level of the L1 vertebral body (arrow). Anterior (C) and posterior (D) planar 99mTc-MDP bone scan images show focal increased osteoblastic activity at L1 and L3 vertebral levels (arrows). Sagittal fused single photon emission computed tomography with computed tomography (E) demonstrates increased activity at the L1 and L3 vertebral bodies. Noncontrast computed tomography images (F) demonstrate corresponding height loss (arrowhead) at the L1 vertebral body and inferior endplate irregularity and linear sclerotic changes (arrow) at the L3 vertebral body, compatible with healing vertebral compression fractures.

A 14-year-old male football player presenting with low back pain. Anteroposterior (A) and lateral (B) spine radiographs show subtle lucency on the lateral view within the L5 pars interarticularis (arrow). Posterior planar 99mTc-MDP bone scan image (C) was unremarkable. Axial noncontrast computed tomography (CT (D) and fused single photon emission CT with CT (E) images demonstrate bilateral pars defects, with asymmetric increased activity within the left pars defect, respectively.

A 56-year-old woman presented with low back pain after prior L4 to S1 posterior instrumented fusion and subsequent standalone L3 to L4 anterior lumbar interbody fusion with anterior plate fixation. Lateral lumbar spine radiograph (A) shows fractured screw related to anterior instrumentation at the level of L4 (arrow). Sagittal T2 magnetic resonance imaging (B) shows no evidence of acute central canal stenosis and metal artifact (arrow) related to instrumentation. Sagittal noncontrast computed tomography (C) demonstrates fractured screw into the L4 vertebral body and sclerotic changes within the bone. Fused sagittal and coronal images demonstrate increased osteoblastic activity and radiotracer uptake within the L3 to L4 disc space concerning for hardware loosening and pseudoarthrosis.

A 54-year-old man presented with persistent axial mechanical neck pain after previously undergoing C4-7 anterior cervical discectomy and fusion 2 years earlier. Anteroposterior (A) and lateral (B) plain films demonstrated all implants from the index surgery were appropriately positioned. Sagittal (C) and coronal computed tomography (CT) reconstructions did not demonstrate any bridging bone across the C4-5 disc space. No residual/recurrent central stenosis was seen on mid-sagittal T2-weighted magnetic resonance imaging (E). Sagittal (F) and coronal (G) single photon emission CT with CT images demonstrated increased radiotracer uptake at the C4-5 level, which suggested symptomatic pseudarthrosis. The patient subsequently underwent posterior cervical instrumented fusion with good result.