Imaging features of 99mTc-MDP SPECT/CT in patients with sacrum insufficiency fracture
CHENG Xiao-jie, LIU Chun-bao, ZHOU Jun-fen, ZHOU Jun, XIA Liang, #br#
DONG Jin-lin, YAN Zhang, LIU Ting, CHENG Li-yun, LU Di-yu
Nuclear Medicine Department, the Central Hospital of Wuhan, Tongji Medical College,
Huazhong University of Science and Technology, Wuhan 430014, China)
Abstract：Objective: To investigate the added value of SPECT/CT by analyzing the imaging features of 99mTc-MDP whole-body bone scan and pelvic SPECT imaging performed in conjunction with low-dose CT fusion imaging in sacral insufficiency fractures(IF). Methods: The clinical and imaging data of 21 patients diagnosed with IF in sacrum by imaging or clinical observation and follow-up were analyzed retrospectively, and the accuracy of the two imaging methods in diagnosing IF in sacrum were compared. Results: Of the 15 cases(71.4%) of sacral IF fractures diagnosed by whole-body bone scanning, 4 cases(26.7%) showed abnormal concentration distribution of imaging agents in the single side of the sacrum wing parallel to the sacroiliac joint, with involvement of the sacral body S2～S3 in two. Eleven cases(73.3%) showed imaging agent distribution of anomaly concentrated area in bilateral sacral wings, including 7 cases of typical “butterfly” shape, “H” shape, 1 case of “bow” form. Twenty cases(95.2%) of sacral IF fractures were diagnosed by pelvic SPECT/CT fusion imaging. There were 12 cases(60%) of bilateral sacral alar fractures, include 9(45%) bilateral sacral alar fractures on CT scan. The irregular low density “sawtooth” fracture bright line and/or hardening belt were only shown in 8(40%) sacral fracture, longitudinal walking line in dual lateral sacral wings, with or without cortical discontinuity in sacral alar margin. Eight cases(40%) were unilateral sacral alar fractures, including 4 cases(20%) of fracture lines in the sacral body perpendicular to the sacroiliac joint. The imaging agent distribution of anomaly concentrated area was only shown in afflicted part of 2(10%) sacral IF patients, but no obvious fracture line was observed on CT of the same machine, focal bone hyperplasia and sclerosis were only showed in 1 case (5%). The accuracy of whole-body bone scan and pelvic SPECT/CT fusion imaging in diagnosing IF of the sacrum were 71.43%(15/21) and 95.2%(20/21), respectively. The accuracy of pelvic SPECT/CT fusion imaging in diagnosing IF of the sacrum was higher than that of whole-body bone scanning, and the difference was statistically significant(P<0.05). Conclusion: IF in sacrum can be diagnosed easily with the typical “H” shape, “sphenoid” shape or “arch” shape of the unusually concentrated imaging agent, but in the case of atypical sacral IF, SPECT/CT fusion imaging of the pelvis can improve the diagnosis accuracy of IF and has added value.
2020, Vol. 31 
