Department of Pediatric Orthopedics, Cohen Children's Medical Center, Northwell Health System, New Hyde Park, NY.
Orthopedic Surgery Program, Nicklaus Children's Hospital, Miami Children's Health Network, Miami, FL.
Spine (Phila Pa 1976). 2017 Nov 15;42(22):E1311-E1317. doi: 10.1097/BRS.0000000000002154.
MINI: The objective of this study was to evaluate the accuracy and reliability of pedicle screw placement using O-Arm at dosages below the manufactured recommended dose. O-Arm at reduced dose showed a 90% accuracy when compared with computed tomography; however, about 30% medial breaches were misclassified.
Cadaveric study.
The objective was to evaluate O-Arm's ability at low-dose (LD) settings to assess intraoperative screw placement.
Accurate placement of pedicle screws is crucial because of proximity to vital structures. Malposition of screws may result in significant morbidity and potential mortality. O-arm provides real-time, intraoperative imaging of patient's anatomy and provides higher accuracy in scoliosis surgeries, avoiding risk to vital structures. We hypothesize using LD or ultra-low doses (ULDs) to obtain intraoperative images allow for accurate assessment of screw placement, both minimizing radiation exposure and preventing screw misplacement.
Eight cadavers were instrumented with pedicle screws bilaterally from T1 to S1. Screws were randomly placed using O-arm navigation into three positions: contained within the bone, OUT-anterior/lateral, and OUT-medial. O-arm images were obtained at three dosage settings: LD (kVp120/mAs125-lowest manufacturer recommended), very-low dose (VLD) (kVp120/mAs63), and ULD (kVp120/mAs39). Computed tomography (CT) scan was performed using institution's LD protocol (kVp100/mAs50) and gross dissection to identify screw positions.
LD, VLD, ULD, and CT for identifying "IN" screws relative to gross dissection had, a mean (standard deviation) sensitivity of 84.2% (±5.7), specificity of 76.1% (±9.3), and accuracy of 79.9% (±3.1) from all three observers. Across the three observers, the interobserver agreement was 0.67 (0.61-0.72) for LD, 0.74 (0.69-0.79) for VLD, 0.61 (0.56-0.66) for ULD, and 0.79 (0.74-0.84) for CT. Effective doses of radiation (mSV) for LD O-arm scan was 2.16, VLD 1.08, ULD 0.68, and our LD CT protocol was 1.05.
Accuracy of pedicle screw placement is similar for O-arm at all doses and CT compared to gross dissection. Interobserver reliability was substantial for VLD and CT. Approximately 30% of medial screw breaches are, however, misclassified. ULD and VLDs can be used for intraoperative navigation and evaluation purposes within these limitations.
N/A.
MINI：本研究旨在评估在低于制造商推荐剂量的情况下使用 O-Arm 进行椎弓根螺钉定位的准确性和可靠性。与计算机断层扫描相比，O-Arm 在低剂量时的准确率为 90%；然而，约 30%的内侧突破被错误分类。
尸体研究。
评估 O-Arm 在低剂量（LD）设置下评估术中螺钉放置的能力。
准确放置椎弓根螺钉至关重要，因为它们靠近重要结构。螺钉的位置不当可能导致严重的发病率和潜在的死亡率。O 臂提供患者解剖结构的实时术中成像，并在脊柱侧凸手术中提供更高的准确性，避免对重要结构的风险。我们假设使用 LD 或超低剂量（ULD）获得术中图像可以准确评估螺钉放置情况，同时最大限度地减少辐射暴露并防止螺钉错位。
8 具尸体双侧从 T1 到 S1 进行椎弓根螺钉固定。使用 O 臂导航随机将螺钉放置在三个位置：包含在骨内、前/外侧 OUT 和内侧 OUT。O 臂图像在三种剂量设置下获得：LD（kVp120/mAs125-制造商推荐的最低剂量）、超低剂量（VLD）（kVp120/mAs63）和超低剂量（ULD）（kVp120/mAs39）。使用机构的 LD 方案（kVp100/mAs50）和大体解剖进行 CT 扫描，以确定螺钉位置。
LD、VLD、ULD 和 CT 相对于大体解剖识别“IN”螺钉的平均（标准差）敏感性分别为 84.2%（±5.7）、76.1%（±9.3）和 79.9%（±3.1）。三位观察者的观察者间一致性分别为 LD 为 0.67（0.61-0.72）、VLD 为 0.74（0.69-0.79）、ULD 为 0.61（0.56-0.66）和 CT 为 0.79（0.74-0.84）。LD O 臂扫描的有效剂量（mSV）为 2.16，VLD 为 1.08，ULD 为 0.68，我们的 LD CT 方案为 1.05。
与大体解剖相比，O 臂在所有剂量和 CT 下的椎弓根螺钉放置准确性相似。VLD 和 CT 的观察者间可靠性较高。然而，约 30%的内侧螺钉突破被错误分类。在这些限制下，ULD 和 VLD 可用于术中导航和评估目的。
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