Imaging features of the postoperative spine: a guide to basic understanding of spine surgical procedures

Abstract

Spinal surgical procedures are becoming more common over the years, and imaging studies can be requested in the postoperative setting, such as a baseline study when implants are used, or when there is a new postoperative issue reported by the patient or even as routine surveillance. Therefore, it helps the surgeon in the appropriate management of cases. In this context, there is increasing importance of the radiologist in the adequate interpretation of postoperative images, as well as in the choice of the most appropriate modality for each case, especially among radiographs, computed tomography, magnetic resonance imaging and nuclear medicine. It is essential to be familiar with the main types of surgical techniques and imaging characteristics of each one, including the type and correct positioning of hardware involved, to differentiate normal and abnormal postoperative appearances. The purpose of this pictorial essay is to illustrate and discuss the more frequently used spine surgical interventions and their imaging characteristics, with an emphasis on classical decompression and fusion/stabilization procedures. Graphical Abstract Key points Plain radiographs remain the main modality for baseline, dynamic evaluation, and follow-ups. CT is the method of choice for assessing bone fusion, hardware integrity and loosening. MRI should be used to evaluate bone marrow and soft tissue complications. Radiologists should be familiar with most performed spinal procedures in order to differentiate normal and abnormal. Critical relevance statement This article discusses the main surgical procedures involved in the spine, which can be didactically divided into decompression, stabilization-fusion, and miscellaneous, as well as the role of diagnostic imaging methods and their main findings in this context.

Imaging Evaluation of Early and Long-Term Complications Associated with the Postoperative Spine

“…수술 후 합병증은 수술 후 시간에 따라 다양하게 나타날 수 있는데, 초기 수술 후 합병증에는 적절하지 않은 수술기구의 위치(instrument malposition), 수술 후 액체 저류(fluid collection) 및 감염(infection) 등이 있고 중장기적인 합병증으로 수술 기구 주변의 골용해, 융합 실패(failure of fusion), 인접한 척추 분절의 질환(adjacent segment disease; 이하 ASD), 경막외 섬유화(epidural fibrosis) 등이 있다( 7 8 9 10 ). 이러한 다양한 합병증이 있을 수 있기 때문에 척추 수술 후 합병증을 정확히 진단하기 위해서는 수술 후 시간에 따른 다양한 합병증을 이해하고 영상학적 특징을 아는 것이 중요하다.…”

“…자기공명영상 촬영은 우수한 연부조직 해상도를 제공하여 척추관, 골수, 척추 주변 연부조직, 척추 주위 액체 저류, 추간판 탈출, 감염 등을 평가하기에 가장 적합한 영상 검사이다( 10 ). 그러나 금속 수술 기구로 인한 magnetic susceptibility artifact은 영상의 왜곡을 일으키는 주요 문제가 되고 이로 인해 금속 수술 기구 및 그 주변을 판정하기가 어렵다.…”

“…높은 대역폭(bandwidth) 및 매트릭스(matrix)를 증가시키고, 통과면 왜곡을 줄이기 위한 더 얇은 단면 등이 이에 해당하며, 이런 변화로 인해 신호 대 잡음비가 줄어들 경우, 샘플링 평균 수를 늘려서 보완할 수 있지만, 이는 MRI 촬영 시간을 늘리는 단점이 있다. 또한 gradient echo 계열 보다는 fast spin echo 계열 시퀀스를, 지방 억제시에는 다른 기법보다 STIR 기법을 이용함으로써 인공물을 최소화할 수 있다( 8 10 17 ).…”

The Role of Magnetic Resonance Imaging and Computed Tomography in Spinal Cord Injury

“…For example, in patients with Ankylosing Spondylitis (AS) or diffuse idiopathic skeletal hyperostosis (DISH), the CT scan will show regions of bony fusion with greater detail than X-ray or MRI [ 10 ]. In a similar fashion, in patients with metallic spinal hardware and concomitant suspected spinal trauma, CT is the best methodology to evaluate the altered bony anatomy and evaluate the hardware itself [ 11 ].…”