[Feasibility of intraoperative diagnosis with a mobile computed tomography scanner]

Three-dimensional intraoperative computed tomography imaging for zygomatic fracture repair

Objectives

Zygomatic complex (ZMC) fractures comprise up to 40% of all facial fractures. Misaligned bone fragments and misplaced fixation hardware traditionally detected postoperatively on plain radiographs of the skull might require re-operation. The intraoperative O-Arm (Medtronic, USA) is a three-dimensional (3D) computed tomographic imaging system.

Materials and Methods

This retrospective single-center study evaluated the utility of O-Arm scanning during corrective surgeries for ZMC and zygomatic arch (ZA) fractures from 2018 to 2020. Three females and 16 males (mean age, 31.52 years; range, 22-48 years) were included. Fracture instability (n=6) and facial deformity (n=15) were the most frequent indications for intraoperative 3D O-Arm scan.

Results

The images demonstrated that all fracture lines were properly reduced and fixed. Another scan performed at the end of the fixation or reduction stage, however, revealed suboptimal results in five of the 19 cases, and further reduction and fixation of the fracture lines were required.

Conclusion

Implementation of an intraoperative O-Arm system in ZMC and ZA fracture surgeries assists in obtaining predictable and accurate results and obviates the need for revision surgeries. The device should be considered for precise operations such as ZMC fracture repairs.

A study protocol for a randomised controlled trial evaluating the effects of intraoperative computed tomography on the outcomes of zygomatic fractures

Background

Zygomaticomaxillary complex (ZMC) and zygomatic arch (ZA) fractures are common injuries resulting from facial trauma and frequently require surgical management (Huang et al., Craniomaxillofac Trauma Reconstr 8(4):271-6, 2015). A substantial number of post-operative functional and cosmetic complications can arise from the surgical management of these fractures. These include scarring, inadequate facial profile restoration, facial asymmetries and diplopia (Ellis et al. J Oral Maxillofac Surg 54(4):386-400, 1996; Yang et al. Oral Maxillofac Surg Clin North Am 23(1):31-45, 2011; Kloss et al. Int J Oral Maxillofac Surg 40(1):33-7, 2011). Intuitively, most of these aforementioned complications arise as a result of inadequate fracture reduction; however, current standard practice is to assess reduction post-operatively through plain radiographs or computed tomography (CT) scans. The role of intra-operative CT scanning to assess the reduction of ZMC/ZA fractures and the potential impact on complications, has thus far not been established.

Methods

This is a prospective randomised controlled trial currently being undertaken at the Royal Brisbane and Women’s Hospital. All patients who require operative management of their ZMC or ZA fractures are offered enrollment in the trial. The patients are randomised into two groups: interventional (intra-operative CT) and control (no intra-operative CT). All patients in each group will have post-operative radiographs taken. From these radiographs, the reduction of the ZMC and/or ZA fracture is graded by a blinded assessor. Patients will be reviewed in clinic at 1 week and 6 weeks post-surgery. During these consultations, all patients will be assessed for scarring, diplopia, facial profile restoration and need for revision surgery.

Discussion

Many complications associated with surgical management of ZMC and ZA fractures involve poor aesthetic results as a direct consequence of inadequate fracture reduction. Inadequate fracture reduction is predictable given that small incisions are used and only limited visualisation of the fractures is possible during the procedure. This is due to a desire to limit scarring and reduce the risk of damage to vital structures in an aesthetically sensitive region of the body. It follows that an intraoperative adjunctive tool such as a CT scan, which can assist in visualisation of the fractures and the subsequent reduction, could potentially improve reduction and reduce complications.

Trial registration

Australian New Zealand Clinical Trials Registry, ACTRN12616000693426. Registered on 26 May 2016.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3625-8) contains supplementary material, which is available to authorized users.

Use of Intraoperative Computed Tomography for Revisional Procedures in Patients with Complex Maxillofacial Trauma

Background:

In patients with panfacial fractures and distorted anatomic landmarks of zygomatic and orbital complex, there is a risk of zygomaticomaxillary complex (ZMC) malpositioning even with the best efforts for surgical repair. This results in increased number of additional procedures to achieve accurate positioning.

Methods:

We describe the usage of intraoperative C-arm cone-beam computed tomographic (CT) scan for ZMC malpositioning in a representative patient with panfacial fractures.

Results:

We have successfully used intraoperative CT scan for ZMC malpositioning in 3 patients. The representative patient had ZMC malposition after the initial attempt of surgical repair without any intraoperative imaging. On using intraoperative CT scan during the next attempt, we were able to reposition the ZMC accurately.

Conclusions:

Intraoperative CT scan might improve the accuracy of ZMC positioning and decrease the chances of potential additional surgeries. In patients with distorted anatomical landmarks and panfacial fractures, it can be especially helpful toward correcting ZMC malposition.

Validation of a new training tool for ultrasound as a diagnostic modality in suspected midfacial fractures

The aim of this study was to test a previously described training tool for ultrasound for use as a first-line imaging modality. Navigated sonography was performed in 10 patients with midfacial fractures diagnosed using computed tomography (CT). One examiner ranked his sonographic findings regarding the presence of a fracture on six predefined anatomic landmarks on a scale from 1 to 5. These results were correlated with CT findings by displaying fused images. In all but three patients fractures were correctly identified using sonography. In the remaining three patients the examiner was unable to determine whether a fracture was present or not. Normally, these patients would have been subjected to conventional radiographs. Ultrasound proved to be a reliable first-line imaging modality for the investigation of suspected midfacial fractures in daily clinical practice, resulting in decreased radiation exposure since conventional radiographs are omitted. According to this algorithm, patients with sonographically confirmed midfacial fractures are examined for surgical planning using cone-beam CT.

Clinical indications and perspectives for intraoperative cone-beam computed tomography in oral and maxillofacial surgery

OBJECTIVES

Intraoperative cone-beam computerized tomography (CBCT) imaging has been introduced in oral and maxillofacial surgery. Using midfacial fractures as the pioneer model, this study describes the spectrum of further promising clinical indications for intraoperative CBCT and a clinical combination with intraoperative navigation.

STUDY DESIGN

One hundred seventy-nine patients admitted for surgical treatment of the facial skeleton were included in the study. Intraoperatively, 3-dimensional images were generated with the mobile CBCT scanner Arcadis Orbic 3D, obtained from Siemens Medical Solutions, in a variety of indications.

RESULTS

The acquisition of the data sets was uncomplicated, and image quality was sufficient to assess the postoperative result in all cases. In the example of a facial gunshot injury, a navigation system for intraoperative localization of the metal foreign bodies was used.

The role of intraoperative ultrasonography in zygomatic complex fracture repair

Intraoperative assessment of the zygomatic arch is very important in achieving adequate repositioning. The correct alignment of the zygomatic arch indicates the proper position of the zygomatic bone and ensures adequate prominence of the lateral midfacial aspect. The aim of this study was to estimate the value of ultrasonography as an intraoperative repositioning control. In a clinical study of 25 patients, ultrasonography was employed for intraoperative visualization of the zygomatic arch before and after fracture repositioning. Twelve patients presented with isolated zygomatic arch fractures and 13 with combined fractures of the zygomatic bone and arch. The ultrasonographic findings were compared to the radiological and clinical findings. Ultrasonography was able to detect all fractures and dislocations of the zygomatic arch. It was possible to assess the repositioning in 24 out of 25 cases using ultrasonography. The ultrasound images were concordant with the radiographs. Clinical assessment by palpation only succeeded in isolated zygomatic arch fractures with an m-shaped impression, whereas it remained uncertain in nearly all cases with a different dislocation pattern. Ultrasonography was rapid and easy to perform, and is recommended as an intraoperative visualizing tool in all midfacial fractures with displacement of the zygomatic arch.

Intraoperative imaging of zygomaticomaxillary complex fractures using a 3D C-arm system

After preclinical studies and evaluation of radiation exposures, intraoperative three-dimensional (3D) C-arm based imaging is now available for the facial skeleton. Fourteen patients admitted for surgical treatment of zygomaticomaxillary complex (ZMC) fractures were included in the study. Preoperative diagnostics and surgical treatment were performed as usual. Intraoperatively, after open reduction, a cone-beam computed tomography (CBCT) dataset was generated using the SIREMOBIL Iso-C3D (Siemens Medical Solutions, Erlangen, Germany). After DICOM-import in eFilm Workstation axial, coronal and sagittal reconstructions were evaluated by five examiners with the help of six defined criteria. In our study, secondary reconstructions were available after 6 min, excluding the time needed for the evaluation of the images. Especially the positioning of the isocentre of the SIREMOBIL Iso-C3D proved to be uncomplicated. Because of the size of the datasets, assessment of the symmetry of the malar projection proved difficult. Best scoring results were found regarding the visualization of the fragment position, bony anchorage of the screws and the fitting of the plates. Remarkable was the low level of metal artefacts in primary and secondary reconstructions. In conclusion, our results demonstrate intraoperative CBCT using the SIREMOBIL Iso-C3D suitable for assessment of postoperative results following ZMC reduction.

Postoperative imaging of zygomaticomaxillary complex fractures using digital volume tomography

PURPOSE

Three-dimensional imaging using digital volume tomography after reduction of zygomaticomaxillary complex fractures was performed and evaluated.

PATIENTS AND METHODS

Ten patients admitted for surgical treatment of zygomaticomaxillary complex fractures were included in the study. All patients were male, aged 17 to 81 years (average, 43.8 years). Preoperative diagnostics and surgical treatment involving open reduction under general anesthesia were performed as usual. One to 3 days (average, 1.6 days) postoperatively, a digital volume tomography data set was generated using the NewTom 9000 (NIM s.r.l., Verona, Italy). After DICOM-import in eFilm Workstation 1.8.3 (Merge Technologies Inc, Milwaukee, WI), axial, coronal, and sagittal reconstructions were evaluated by 6 examiners with the help of 5 defined criteria.

RESULTS

One data set was sufficient to visualize all fracture sites of the midface in all patients. Postprocessing using eFilm was successfully performed in all cases. Best scoring results were found regarding bony anchorage of screws and fitting of plates. Remarkable was the low level of metal artifacts in primary and secondary reconstructions, even in close proximity of the material. Most difficulty was encountered during the identification of the medial orbital wall, especially next to poorly ventilated ethmoidal cells. Osseous structures of older patients with decreased bone density proved difficult to visualize.

CONCLUSION

Digital volume tomography using the NewTom 9000 is suitable for assessment of postoperative results after zygomaticomaxillary complex reduction.

Radiation exposure during midfacial imaging using 4- and 16-slice computed tomography, cone beam computed tomography systems and conventional radiography

OBJECTIVES

Radiation doses were determined to balance risks against usefulness of the different modalities available for the imaging of the facial skeleton.

METHODS

An Alderson Rando Phantom, armed with lithium fluoride thermoluminescent dosemeters (TLDs) was exposed using a set of four conventional radiographs (orbital view, modified Waters view, orthopantomography, skull posterior--anterior 0 degrees ), two different cone beam computed tomography (CBCT) (NewTom 9000 and Siremobil Iso-C3D), and multislice computed tomography (CT) modalities (Somatom VolumeZoom and Somatom Sensation 16). TLDs from 14 well defined anatomical sites lying within the primary beam as well as the TLD corresponding to the thyroid gland were evaluated.

RESULTS

Multislice CT showed the highest exposure values. Exposure levels of the CBCT systems lay between CT and conventional radiography. Dose measurement for the 16-slice CT revealed nearly the same radiation exposure as the 4-slice system when adapted examination protocols were used.

CONCLUSIONS

Selection of the most appropriate imaging modality should be performed in view of the delivered doses, required image quality and information and the clinical circumstances.

[Sonography as a training tool for screening of dubious midfacial fractures]

BACKGROUND

In uncertain midfacial fractures, sonography is an alternative first-line imaging modality to conventional radiographs. Patients with sonographically confirmed fractures can then be directly admitted to three-dimensional imaging, resulting in decreased radiation exposure since the conventional radiographs are omitted.

MATERIAL AND METHODS

Using a high-frequency linear and curved array scanner in a healthy proband, images of the zygomatic arch, anterior maxillary sinus wall, infraorbital rim, and lateral orbital wall were obtained. For identification and anatomical allocation corresponding navigated ultrasound images of a reference skull were generated and fused with a segmented CT data set. Navigated sonography was reproduced in a patient with orbitozygomatical fracture of the left side. Therefore, the CT data set, performed during preoperative diagnostics, was fused with the ultrasound images.

RESULTS

Because of different coupling shapes, the high-frequency linear array scanner was subjectively found to be more suitable for sonography in the field of the zygomatic arch, anterior maxillary sinus wall, and infraorbital rim, and the curved array scanner was better suited for transbulbar sonography of the orbital walls. After coupling sonography with the navigation system and referencing the scanner, it was possible to verify ultrasound findings objectively by navigation of the scanner and fusion with the CT data set. Using the reference skull, ultrasound images corresponding to normal findings were obtained and with the fused CT data, providing colored segmentation of the facial bones, an anatomically correct identification was possible. Clinical application of this tool is described in a patient with left-sided orbitozygomatical fracture.

CONCLUSION

By fusion of ultrasound images and corresponding CT data with the help of a navigation system, a sonographic training tool for preliminary evaluation of midfacial fractures is available.

Intraoperative 3D imaging of the facial skeleton using the SIREMOBIL Iso-C3D

OBJECTIVES

With respect to high-contrast structures, cone beam computed tomography (CBCT) offers an alternative imaging modality to computed tomography (CT), requiring less radiation exposure. The C-arm system SIREMOBIL Iso-C3D for three-dimensional (3D) reconstruction has made this modality available for intraoperative use. This paper presents the first intraoperative images of the facial skeleton using the SIREMOBIL Iso-C3D.

METHODS

Cases of a zygomaticomaxillary complex fracture, a mandibular angle fracture and a bimaxillary repositioning osteotomy are described to demonstrate the application possibilities of this system in maxillofacial surgery.

RESULTS

In addition to the uncomplicated handling of the SIREMOBIL Iso-C3D, generally important was the low level of metal artefacts in its primary and secondary reconstructions, even in close proximity to the material. However, it has to be kept in mind that while soft tissues are visualized using CBCT, information about soft tissue quality cannot be obtained.

CONCLUSION

The SIREMOBIL Iso-C3D generates intraoperative data sets suitable for the visualization of the facial bones after open reduction of fractures.

Dreidimensionale Darstellungsmöglichkeiten des Mittelgesichts mithilfe der digitalen Volumentomographie anhand einer Kadaverstudie zur winkelstabilen Osteosynthese

BACKGROUND

Multidirectional angularly stable interlocking plate systems are now available for the surgical treatment of the midface. After first experiences in cases of mandibular fractures, application to the facial skeleton was investigated using a cadaver study. Furthermore, three-dimensional imaging by means of the digital volume tomograph NewTom DVT 9000 after reduction of orbitozygomatical fractures was performed and evaluated.

MATERIAL AND METHODS

After artificial osteotomy and reduction of both zygomatical complexes, osteosynthesis of the left side was performed with three 4-hole miniplates (2.0). On the right side, three angular stable 2-hole plates (2.3) were used. Thereafter, a three-dimensional data set was generated using the NewTom DVT 9000. After DICOM-import in eFilm reconstructions were evaluated by six examiners regarding defined criteria.

RESULTS

After adaptation and fixation of the angular stable interlocking plate system without complications, manual checking revealed that the primary stability did not seem inferior to the other side. Defined criteria were sufficiently evaluable, even close to the osteosynthetic material, using reconstructions of the digital volume tomography data set.

CONCLUSION

Surgical treatment of midfacial fractures using a multidirectional angularly stable interlocking plate system seems promising. The NewTom DVT 9000 proved to be suitable to visualize even fine osseous structures of the midface.