[Reproducibility of readings of ISO C 3D and CT lumbar pedicle screw scans]

Evaluation of Software-Based Metal Artifact Reduction in Intraoperative 3D Imaging of the Spine Using a Mobile Cone Beam CT

The aim of our study was to evaluate whether software-based artifact reduction can achieve an improved image quality, using intraoperative 3D imaging in spinal surgery. A total of 49 intraoperative 3D image datasets of patients, who underwent surgery with pedicle screw placement, were retrospectively evaluated. The visibility of anatomical structures and the diameter of the pedicle screws were examined, with and without the application of the artifact reduction software. All software prototypes can improve the visibility of anatomical structures (P < 0.01), except MAR (metal artifact reduction) combined with IRIS (iterative reconstruction in image space) (P = 0.04). The algorithms MAR and MAR-2 can reduce the blooming artifacts significantly (P < 0.01), but SL (Shepp & Logan) cannot (P = 0.08-0.988). In summary, software-based artifact reduction for intraoperative 3D datasets can improve the current image quality. Additional information regarding the implant placement and the fracture reduction is therefore generated for the surgeon.

Advantages and Disadvantages of Multi-axis Intraoperative Angiography Unit for Percutaneous Pedicle Screw Placement in the Lumbar Spine

We analyzed clinical usefulness of the high resolution imaging system in a hybrid operation room (OR) for posterior lumbar interbody fusion. A total of 17 patients with lumbar spondylolisthesis between February 2014 and August 2016 were included. Multi-axis imaging system in a hybrid OR was used in 12 patients (hybrid OR group); the conventional C-arm fluoroscopy, in 5 patients (C-arm group). The time to confirm the first percutaneous pedicle screw (PPS) angle (hybrid OR, 80 vs C-arm, 249 s; P = 0.0026) and the second to the last PPS angle (77 vs 90 s; P = 0.040) were shorter in the hybrid OR group. Placement accuracy was higher in the hybrid OR group (88.0 vs 59.1%; P = 0.010). Irradiation dose was significantly lower in the C-arm group (462 vs 102 mGy; P = 0.0013). This study suggested that the accuracy of PPS placement and time to confirm the PPS angle are the advantages in a hybrid OR.

[Intraoperative 3D C-arm imaging. State of the art]

Mobile C-arms with the option of 3D imaging like the Iso-C(3D) allow for intraoperative 3D visualization of anatomical areas with complex three-dimensional structures like articular surfaces. In an 8-year period we performed 1,841 intraoperative control scans following osteosynthesis. Among these patients we registered the number of intraoperative adjustments of fracture reduction and implant position in correlation to the area of surgery. The majority of intraoperative examinations in 1,841 patients was performed in fractures of the calcaneus (20.5%) and the upper ankle joint (13.2%). Altogether we improved the reduction or the implant position intraoperatively in 21.5%. The majority of intraoperative revisions was seen in osteosynthesis of the calcaneus (40.3%), the upper ankle joint (30.9%) and fractures of the distal tibia (29%). The rate of revisions over the time was very stable. Intraoperative need for revision of reduction or implant position is not a rare phenomenon in our experience. Intraoperative 3D imaging is a valid tool to recognize and adjust suboptimal reduction or implant positioning. Intraoperative 3D imaging can improve the quality of osteosynthesis especially in fractures of joints and complex anatomical areas.

Assessment of two 3-D fluoroscopic systems for articular fracture reduction: a cadaver study

OBJECTIVE

The most commonly used imaging device for assessment of fracture reduction is the two-dimensional X-ray fluoroscope. Two recently introduced 3D fluoroscopic devices, the Siremobil ISO-C3D (Siemens) and the C-InSight (Mazor Surgical Technologies), enable the surgeon to obtain spatial information for the assessment of articular reduction and hardware placement. The purpose of this study was to assess the reliability and accuracy of these two 3D fluoroscopic systems in measuring articular reduction in a cadaveric tibial plateau fracture.

METHODS

Six cadaveric knee specimens were osteotomized at the lateral tibial plateau and fixed with a maximal articular step-off of 0, 1, 2.5, 5 and 7.5 mm. Each specimen was scanned 10 times with two 3D fluoroscopes, the Siremobil ISO-C3D and the C-InSight. The resulting images were reformatted and interpreted for articular displacements at four different locations at the plateau level and were compared with high-resolution CT scans by an independent observer.

RESULTS

For the non-displaced fracture, no displacement (mean < 0.1 mm) was observed in either modality. The mean scanning time for the ISO-C3D was 2 min, while each C-InSight scan took 20 s. The readings at four different points along the malreduced fractures were similar for most measurements with either of the two modalities. The C-InSight readings were less accurate than those of the ISO-C3D, relative to the CT scan, but most errors were within clinically acceptable limits (< 2 mm) and used less radiation.

CONCLUSIONS

Intraoperative 3D fluoroscopes can detect clinically significant intra-articular step-off with acceptable measurement errors, using newer devices that enable the use of a conventional C-arm and reduced radiation.