gms | German Medical Science

Objective: Adequate evaluation of the spinal canal and the neuroforaminal pathologies in patients after spinal stabilization via CT or MRI remains a difficult task due to metal-related artifacts. Alternatively, more invasive imaging techniques like CT-myelography are often necessary. One promising image modality could be the use of a dual-energy CT that acquires two CT datasets with different X-ray spectra. This technology allows the reduction of metal-related artifacts and a better assessment of the neural structures. Aim of this study was to evaluate whether the detection of remnant, recurrent or adjacent spinal pathologies could be improved by use of a 3^rd generation dual-source CT in patients after spinal stabilization.

Methods: Spinal imaging was obtained with a 3^rd generation dual-source CT in all patients that were due for follow-up imaging or presented with new symptoms after cervical, thoracic or lumbosacral spinal stabilization. Low tube voltage monoenergetic datasets were calculated in 10 keV intervals from 40-190 keV. Software calculated standard CT protocol image sets were simultaneously generated for comparative analysis. The image quality was independently evaluated by two experienced neurosurgeons through choosing the subjectively best image quality of all performed datasets in comparison to standard CT imaging. A 5-point Likert scale was used regarding overall image quality, foraminal stenosis or other osseous pathologies.

Results: A total of 25 patients after spinal stabilization surgery were included. The gender distribution was balanced (12 men and 13 women). Mean age of the patient collective was 57 years (range 30-77y). Many of the patients had previously received cervical surgery (16 out of 25; 64%). The remaining collective of 9 patients (36%) had previously underwent lumbar stabilization. The overall image quality was rated superior by one neurosurgeon in 23 of the 25 cases and in 24 by the other neurosurgeon. A relevant reduction of metal-related artifacts was seen at higher keV ranges of 170 keV to 190 keV with the maximum artefact reduction seen at 190 keV. Newly detected osseous pathologies were visable in 8 of the 25 patients at 190 keV in comparison to only 2 with standard CT protocol or datasets below a 120keV.

Conclusion: Performing a 3^rd generation dual-source CT for follow-up evaluations in patients after spinal surgery with metal implants seems to be a promising alternative to standard CT or MRI due to the immense reduction of metal-related artefacts. Additional invasive diagnostic methods could therefore be avoided in future. Furthermore, it can be used as an applicable modality in patients with contraindications for MRI.