Single photon emission computed tomography (SPECT) for low back pain induced by extension with no root sign

Low back pain (LBP) is very common in the general population. Most patients with LBP will receive an X-ray examination on lumbar spine; however, the results are likely to show a negative finding or degenerative joint disease, which are not truly pathological factors. Among various imaging diagnostic tools for active bony lesions of lumbar spine, planar bone scintigraphy has a higher sensitivity, but its ability to locate anatomic lesions is less satisfactory. The purpose of this study was to investigate the role of SPECT for evaluation of LBP.

Fifty-two consecutive patients who had low back pain induced by extension were studied. They had no evidence of malignant tumor, immune disease, spinal infection and neurological disorder by history-taking and physical examination. All patients received planar bone scintigraphy and SPECT exams following an X-ray examination. The results of X-ray finding were grouped into 3 categories: (A) normal; (B) degenerative joint arthritis; (C) spondylolysis. The data of test results and clinical evaluation were then used for analysis.

Twenty (38.5%) out of 52 patients examined by planar scan had abnormality, with 29 increased uptake lesions, compared with 28 (53.8%) out of 52 patients with 60 increased uptake lesions by SPECT with planar scan; SPECT disclosed 1-2 more lesions with improved location in 15 patients (p < 0.05). Of the 52 patients, 21 (40.4%) presented in group A, 21 (40.4%) in group B, and 10 (19.2%) in group C according to the X-ray examination. In group A, 9 out of 21 (42.9%) patients had an abnormal SPECT result, compared to 5 of 10 (50%) in group B, and 14 out of 21 (66.7%) in group C, respectively (p > 0.05). The location of abnormal uptake on L-spine included vertebral body and arch (57.1%), vertebral arch (28.6%), and vertebral body (14.3%). Most of lesions (91.5%) were distributed at the 4th and 5th lumbar vertebral segments.

SPECT was more sensitive and located more lesions than planar bone scintigraphy, especially when the lesions were located at posterior element of vertebrae. Most of the lesions were distributed at the 4 th and 5 th lumbar vertebral segments. There was no significant statistical difference of abnormal SPECT related to X-ray finding. The use of SPECT was the first choice among all image modalities when cause of low back pain was assumed to arise from bone and joint disorder at clinical evaluation.