Comparison of Intraoperative Portable CT Scanners in Skull Base and Endoscopic Sinus Surgery: Single Center Case Series

Precise and safe management of complex skull base lesions can be enhanced by intraoperative computed tomography (CT) scanning. Surgery in these areas requires real-time feedback of anatomic landmarks. Several portable CT scanners are currently available. We present a comparison of our clinical experience with three portable scanners in skull base and craniofacial surgery. We present clinical case series and the participants were from the Northwestern Memorial Hospital. Three scanners are studied: one conventional multidetector CT (MDCT), two digital flat panel cone-beam CT (CBCT) devices. Technical considerations, ease of use, image characteristics, and integration with image guidance are presented for each device. All three scanners provide good quality images. Intraoperative scanning can be used to update the image guidance system in real time. The conventional MDCT is unique in its ability to resolve soft tissue. The flat panel CBCT scanners generally emit lower levels of radiation and have less metal artifact effect. In this series, intraoperative CT scanning was technically feasible and deemed useful in surgical decision-making in 75% of patients. Intraoperative portable CT scanning has significant utility in complex skull base surgery. This technology informs the surgeon of the precise extent of dissection and updates intraoperative stereotactic navigation.     

Intraoperative cone-beam CT for image-guided tibial plateau fracture reduction.

OBJECTIVES: A mobile isocentric C-arm was modified in our laboratory in collaboration with Siemens Medical Solutions to include a large-area flat-panel detector providing multi-mode fluoroscopy and cone-beam CT (CBCT) imaging. This technology is an important advance over existing intraoperative imaging (e.g., Iso-C(3D)), offering superior image quality, increased field of view, higher spatial resolution, and soft-tissue visibility. The aim of this study was to assess the system's performance and image quality in tibial plateau (TP) fracture reconstruction. METHODS: Three TP fractures were simulated in fresh-frozen cadaveric knees through combined axial loading and lateral impact. The fractures were reduced through a lateral approach and assessed by fluoroscopy. The reconstruction was then assessed using CBCT. If necessary, further reduction and localization of remaining displaced bone fragments was performed using CBCT images for guidance. CBCT image quality was assessed with respect to projection speed, dose and filtering technique. RESULTS: CBCT imaging provided exquisite visualization of articular details, subtle fragment detection and localization, and confirmation of reduction and implant placement. After fluoroscopic images indicated successful initial reduction, CBCT imaging revealed areas of malalignment and displaced fragments. CBCT facilitated fragment localization and improved anatomic reduction. CBCT image noise increased gradually with reduced dose, but little difference in images resulted from increased projections. High-resolution reconstruction provided better delineation of plateau depressions. CONCLUSION: This study demonstrated a clear advantage of intraoperative CBCT over 2D fluoroscopy and Iso-C(3D) in TP fracture fixation. CBCT imaging provided benefits in fracture type diagnosis, localization of fracture fragments, and intraoperative 3D confirmation of anatomic reduction.     

术中即时三维导航在后凸成形术中的应用

目的 探讨应用术中即时三维导航行后凸成形术(PKP)治疗骨质疏松性椎体压缩性骨折的方法、疗效及适应证的选择. 方法 2006年4月至2009年8月在术中即时三维导航引导下行经皮穿刺PKP 15例(44个椎体).比较手术前、后视觉模拟法(VAS)评分、伤椎前后缘高度及伤椎Cobb角变化. 结果 15例患者术后第1～2天均可佩戴胸腰骶支具下地活动,VAS评分、伤椎前后缘高度及Cobb角均较术前明显恢复,差异均有统计学意义(P<0.05).术中穿刺针及工作通道置入位置准确,未发现椎弓根穿破的患者,围手术期无肺柃塞、神经功能障碍等并发症发生.所有患者随访3～14个月,平均7.1个月;未次随访X线片示骨折愈合良好,未发现手术节段椎体再次塌陷. 结论应用术中即时三维导航行PKP可以明显提高手术的精确度和安全性,简化手术步骤,减少辐射的危害和手术并发症,疗效肯定.行PKP治疗骨质疏松性椎体压缩性骨折时,如存在多发骨折(≥3个椎体)、中上胸椎骨折、骨折压缩严重或严重骨质疏松等情况,应考虑应用术中即时三维导航进行辅助.     

Computer modeling and intraoperative navigation in maxillofacial surgery.

PURPOSE: Recent advances in computer-modeling software allow reconstruction of facial symmetry in a virtual environment. This study evaluates the use of preoperative computer modeling and intraoperative navigation to guide reconstruction of the maxillofacial skeleton. METHODS: Three patients with traumatic maxillofacial deformities received preoperative, thin-cut axial CT scans. Three-dimensional reconstructions, virtual osteotomies, and bony reductions were performed using MIMICS planning software (Materialise, Ann Arbor, MI). The original and "repaired" virtual datasets were then imported into an intraoperative navigation system and used to guide the surgical repair. RESULTS: Postoperative CT scans and photographs reveal excellent correction of enophthalmos to within 1 mm in patient 1, significant improvement in symmetry of the nasoethmoid complex in patient 2, and reconstruction of the zygomaticomaxillary complex location to within 1 mm in patient 3. CONCLUSION: Computer modeling and intraoperative navigation is a relatively new tool that can assist surgeons with reconstruction of the maxillofacial skeleton.     

治疗小颏畸形的三种术式对比分析

目的 对比分析硅胶假体置入隆颏术、自体骨移植隆颏术和颏部水平截骨颏成形术的临床效果和常见并发症。方法 通过三维CT、头颅正侧位X线检查和第2次手术观察，分析三种治疗小颏畸形手术各自的优缺点并明确其适应证。结果 硅胶假体置入隆颏术后存在假体位置异常、颏部骨质吸收、假体周围骨膜反应、颏部矫正不足等缺点；自体骨移植隆颏术后存在较严重的远期移植骨质吸收和颏部形态改善不足问题；颏部水平截骨颏成形术矫正小颏畸形效果良好。结论 硅胶假体置入隆颏术适用于轻度的下面部矢状方向发育不良、不伴有前下面高不足、无面部不对称且颏唇沟较浅的患者。颏部水平截骨颏成形术适用于各种程度及类型的小颏畸形的矫治，尤其适用于颏部偏斜和面部不对称的调整。自体骨移植隆颏术长期效果不佳，应谨慎使用。     

Indications for computer-assisted treatment of cranio-maxillofacial tumors.

OBJECTIVE: Ablative tumor surgery requires detailed planning using computed tomography (CT) or magnetic resonance imaging (MRI). Reconstruction following tumor resection is dependent on reliable information for choosing the correct type and volume of grafts and predicting the outcome. This study evaluates the benefit of and the indications for computer-assisted surgery in the treatment of cranio-maxillofacial tumors. MATERIALS AND METHODS: Based on a CT or MRI data set, the STN Navigation System (Stryker-Leibinger) was used for preoperative planning, intraoperative navigation, and postoperative control of radical tumor resection and primary and secondary reconstruction. Tumor resection was preoperatively planned and intraoperatively navigated. Preoperatively, the required soft and hard tissue were measured using the mirrored data set of the unaffected side of the facial skeleton; the size and location of the graft were chosen virtually. Intraoperatively, contours of transplanted tissues were navigated in accordance with the preoperatively simulated reconstructive result. RESULTS: Computer-assisted treatment was successfully completed in all cases of radical tumor resection, and safety margins outlined preoperatively could be precisely controlled during tumor resection. Reconstruction was designed and performed exactly as virtually planned. CONCLUSIONS: Image-guided treatment improves preoperative planning by visualization of the individual anatomy and the intended reconstructive outcome, and by objectivation of the effect of adjuvant chemo-/radiotherapy. Intraoperative navigation makes radical tumor surgery more reliable by showing the determined safety margins, preserving vital structures, and guiding reconstruction to preplanned objectives.     

3D打印模型联合吲哚菁绿荧光导航行腹腔镜下精准肝切除术

目的 探讨三维（three-dimensional,3D）打印模型联合吲哚菁绿（indocyanine green,ICG）荧光导航在腹腔镜下精准肝切除术中的临床应用价值。方法 基于CT数据建模,采用镂空技术1:1 打印出1 例肝内胆管结石的3D肝脏模型,进行术前规划,并联合ICG荧光导航行腹腔镜下精准肝切除术。回顾性分析手术方案的制定及术中、术后临床资料。结果 基于3D打印肝脏模型,手术方案从肝V/VIII段切除改为肝V段切除。3D打印模型与肝内结构吻合,可直视肝内复杂管道,联合ICG术中导航顺利完成腹腔镜下精准肝切除术。手术时间约210 min,其中肝切除时间约100 min,术中出血量约50 mL,术中无输血。术后无腹腔出血、腹腔感染、胆漏等并发症。结论 采用3D打印肝脏模型联合ICG荧光导航为腹腔镜下精准肝切除术提供了一种新技术。     

Integrierte Navigation

BACKGROUND: Computer navigation systems have increasingly become part of the surgical routine due to the improvements of intraoperative visualization procedures. Because of limited space in the operating room and insufficient workflow, the project of integrated navigation had been started. METHODS: As the first step, the navigation system VectorVision2 and the second-generation fluoroscopic C-arm system Orbic 3D were integrated into one common trolley. In an experimental study the integrated navigation system was used to drill 160 pedicle screws. Afterwards the system was clinically evaluated in 11 surgical procedures. RESULTS: During the whole experimental study the system could be used for all 160 drilling procedures without any technical faults, causing a failure rate of 4.2%. For clinical evaluation the integrated navigation system was used in seven patients with navigated dorsal spine instrumentation, in three cases sacroiliac screws were placed, and in one case supra-acetabular screw osteosynthesis was performed for an acetabular fracture. In all cases the positioning of the screws was correct and no system failure occurred. CONCLUSIONS: The combination of the navigation system and the C-arm system in one common trolley is a major improvement of the surgical workflow. In the experimental study and the clinical trials the system worked extremely reliably and with high precision.     

Three-dimensional rotational angiography guidance for aneurysm surgery

OBJECT: The aim of this study was to investigate the feasibility of integrating three-dimensional rotational angiography (3D-RA) data into a surgical navigation system and to assess its accuracy and potential clinical benefit. METHODS: The study cohort consisted of 16 patients with 16 intracranial aneurysms who had been scheduled for routine or emergency surgery. Rotational angiography data were exported using a virtual reality modeling language file format and imported into the BrainLAB VectorVision2 image-guided surgery equipment. During 3D-RA the position of the head was measured using a special headframe. The authors also determined the accuracy of 3D-RA image guidance and the clinical benefit as judged by the surgeon, including, for example, early identification of branching vessels and the aneurysm. There was good correspondence between the 3D-RA-based navigation data and the intraoperative vascular anatomy in all cases, with a maximum error of 9 degrees of angulation and 9 degrees of rotation. In eight cases, the surgeon determined that the 3D-RA image guidance facilitated the surgical procedure by predicting the location of the aneurysm or the origin of a branching artery that had been covered by brain tissue and blood clots. CONCLUSIONS: The integration of 3D-RA into surgical navigation systems is feasible, but it currently requires a new perspective-registration technique. The intraoperative 3D view provides useful information about the vascular anatomy and may improve the quality of aneurysm surgery in selected cases.     

Rekonstruktion nach Trauma

The facial skeleton is often affected by injuries which may leave patients not only with esthetic but also functional deficits. Computer-assisted reconstruction enables the operating surgeon to achieve predictable results of reconstruction of the facial skeleton. The combination of virtual preoperative planning, intraoperative navigation and intraoperative imaging is routinely used to treat trauma of the facial skeleton at the authors’ hospital. With preoperative planning, the desired outcome of reconstruction can be accurately planned and implemented using intraoperative imaging and navigation. Intraoperative imaging complements treatment, allowing additional intraoperative validation of the results of surgery. Using computer-assisted surgery in treating trauma of the facial skeleton helps to avoid incorrect positioning of bone fragments and inserted implants. This represents a substantial progress in such complex operations and reduces the number of secondary reconstructions.     

Fluoroscopy-guided vs. navigated iliosacral screw placement with intraoperative 3D scan or postoperative CT control: Impact of the clinical workflow on patients’ radiation exposure: Radiation exposure of different workflows for iliosacral screw placement

IntroductionTo guide iliosacral screws (ISS) and verify safe placement different techniques, e.g. Fluoroscopy-guided (FSG) or 3D navigation are known. However, higher radiation exposure for the conventional technique is a concern. It was the aim of this experimental study to evaluate radiation exposure for three clinical workflows.MethodsAn anthropomorphic, cross sectional dosimetry phantom was equipped with metal oxide semiconductor field effect transistors to measure organ specific radiation exposure. The effective dose was calculated. Radiation exposure was measured for FSG placement of 2 transverse ISS based on clinical experience regarding fluoroscopy time (240s). Additional measurements were conducted to calculate the effective dose for an intraoperative 3D scan as used for navigated ISS (high-quality 3D), for intraoperative verification of proper guide wire placement (standard-quality 3D) and for postoperative CT, using three different protocols. The following workflows were compared: FSG including postoperative CT (FSG-CT, including 3 different protocols) vs. FSG with intraoperative 3D scan in standard quality (FSG-3D) vs. navigation including two intraoperative 3D scan for navigated ISS (NAV-3D).ResultsThe effective dose for FSG-CT ranged from 4.41 mSv to 5.27 mSv. FSG-3D resulted in a total of 4.93 mSv. For NAV-3D, the effective dose was the lowest (3.00 mSv). The effective dose of a high-quality 3D scan required for navigation was 1.94 mSv, compared to 1.06 mSv for a standard-quality 3D scan as used for control.ConclusionsIntraoperative 3D scanning may be recommended, either combined with prior FSG ISS placement or following 3D navigation without increasing radiation exposure compared with alternative workflows with postoperative CT control.     

An in-vitro study to assess the feasibility,validity and precision of capturing oncology facial defects with multimodal image fusion

Aim

Assess the feasibility, validity and precision of multimodal image fusion to capture oncology facial defects based on plaster casts.

Fluoroskopiebasierte 3D-Navigation komplexer Korrekturosteotomien des proximalen Femurs

BACKGROUND: Despite great advances in hip alloarthroplasty there are still numerous indications for joint-saving procedures such as correction osteotomies. Often these procedures include complex 3D rearrangements of the proximal femur, which are for the surgeon technically very demanding. The project aim was to develop a precise intraoperative virtual 3D planning tool including a detailed biomechanical analysis and enable the surgeon to realize exactly this plan by using computer-assisted techniques. METHODS: Using only two different angled fluoro frames a simplified femoral model was inversely constructed. For navigation a passive optical system was used with a C-arm calibration kit and PC-based software. For in vitro evaluation complex osteotomies were performed on ten femora under simulated OR conditions. RESULTS: The mean difference between the planning and real surgical outcome for the wedge size was less then 2 degrees and for the femur head center position less then 4 mm. No implant penetrated the femur neck isthmus. CONCLUSION: Without changing the standard operative procedure the method can be of high clinical importance to improve planning accuracy and consecutive operative realization for precise fragment positioning and plate location without penetrating the isthmus of the femoral neck. And -- besides precision -- it can potentially help to reduce intraoperative complications such as implant penetration and minimize X-ray use.     

Hemifacial spasm: intraoperative electromyographic monitoring as a guide for microvascular decompression

OBJECTIVE: Microvascular decompression is the logical and well-accepted treatment of choice for hemifacial spasm (HFS). In experienced hands, good to excellent results can be obtained. However, sometimes the exact site of the vascular compression is unclear. The aim of this study was to analyze whether intraoperative monitoring by stimulated electromyography of the facial nerve may help to improve the results of vascular decompression for HFS. METHODS: In a series of 74 patients operated for HFS, the impact of intraoperative facial nerve monitoring on the surgical procedure was analyzed by use of the clinical and operative patient records. The role of this type of monitoring, with assessment of the so-called abnormal muscle response, was broken down into four categories: a guiding, a confirming, an indirect confirming, or an inconclusive role. The relationship between abnormal muscle response monitoring results and final surgical outcome was analyzed. RESULTS: The overall cure rate was 87.8%, including patients who had previously undergone unsuccessful operations. Complications were minor, and hearing impairment was found in 2.7% of patients. A guiding role of intraoperative monitoring was apparent in 33.8% of patients, and a confirming role was demonstrated in 52.7% of patients, which resulted in a positive contribution of approximately 87% for intraoperative facial monitoring in microvascular decompression for HFS. In patients defined as guiding cases, the cure rate was 92%. CONCLUSION: This study demonstrates the applicability and usefulness of intraoperative facial nerve monitoring in microvascular decompression operations for HFS.     

Navigated percutaneous versus open pedicle screw implantation using intraoperative CT and robotic cone-beam CT imaging

Percutaneous paraspinal pedicle screw implantation (PPSI) reduces soft tissue trauma, blood loss, and postoperative pain but remains technically challenging and associated with radiation exposure and implant-related artefacts. Here, we determined the feasibility, screw accessibility, and the accuracy of navigated PPSI in the thoraco-lumbar sacral spine using intraoperative computed tomography (iCT) and robotic cone-beam CT (CBCT) imaging. Between 2015 and 2018, 465 percutaneous paraspinal pedicle screws were implanted in 75 patients using iCT- or CBCT-based spinal navigation with 230 screws connected to rod reducers during screw assessment imaging (iCT 198; CBCT 32). Clinical and demographic data, intraoperative screw accessibility, and screw accuracy were analyzed and compared to a case-matched cohort of 75 patients undergoing navigated implantation of 481 pedicle screws through an open midline approach. Both iCT and CBCT permitted reliable assessment of each implanted screw, regardless of artifacts caused by rod reducers. Although overall accuracy for correct placement was comparable between PPSI and open surgery (PPSI 96.6%; Open 94.2%), PPSI compared favorably to open surgery regarding complete placement within the pedicle (PPSI 90.1%; Open 75.1%; p  <  0.0001), regional placement accuracy in the lumbar (PPSI 97.8%; Open 91.5%; p  <  0.001), and lumbar-sacral spine (PPSI 100%; Open 81.2%; p  <  0.05), next to the duration of surgery and length of hospitalization. PPSI with iCT- and CBCT-based spinal navigation improves the accuracy, safety, and workflow of navigated spinal instrumentation. Next, a cost-effectiveness and outcome analysis should determine whether iCT and CBCT imaging are truly economically justified. These slides can be retrieved under Electronic Supplementary Material.     

Periazetabuläre Navigation

Following a period of conservative treatment of acetabular fractures in the past, the use of classifications and defined acetabular surgery indications was introduced because of an increasing number of extended surgical approaches for operative stabilization of acetabular fractures. This development has enabled minimally invasive procedures using three-dimensional (3D) visualization and navigation techniques in the operating room (OR), with the expectation of reduced intraoperative morbidity and optimized surgical precision. Most common in acetabular navigation is 3D C-arm-based navigation, which has enabled new techniques in combination with other modern OR systems. In special cases, techniques based on computed tomography and 2D C-arms are still used.     

虚拟手术计划联合术中导航辅助上颌骨肿瘤切除及同期修复

目的探讨虚拟手术计划联合术中导航在上颌骨肿瘤切除和修复重建中的应用。方法回顾性分析2015年10月至2016年12月于郑州大学第一附属医院口腔颌面外科就诊的上颌骨肿瘤患者资料。术前通过计算机完成肿瘤描记,模拟肿瘤切除和腓骨重建手术,打印三维模型并制作手术导板和个性化钛网。术中应用导航确定手术计划中上颌骨截骨线位置,实施肿瘤精确切除。依据手术计划和腓骨截骨导板引导腓骨塑形,联合个性化预成形钛网重建颌骨缺损。采用组织病理学检查评估肿瘤切除手术边界安全性,采用术后腓骨位置与术前设计配准颜色梯度图、患者面部外形满意度评价、开口度和颌间距离评价上颌骨缺损修复重建效果。结果该研究共纳入5例患者,男3例,女2例,年龄27~50岁,中位年龄39岁。其中良性肿瘤2例,恶性肿瘤3例。上颌肿瘤切除和腓骨瓣修复重建手术过程顺利,腓骨瓣均成活。手术切缘冰冻病理检查共27处,25处结果阴性,2处(同一患者)结果阳性。术后1例患者辅助生物治疗和放疗,2例放疗。术后颜色梯度图显示腓骨实际位置与术前设计高度吻合,随访半年时4例患者面部外形满意度自评为优,1例为良。患者开口度2.8~3.2 cm,闭口位腓骨修复区域上下颌颌间距离6.5~10.0 mm。随访14~28个月,1例手术切缘阳性患者局部复发。结论虚拟手术计划联合术中导航可以提高上颌骨肿瘤切除和修复重建精确性,有利于患者术后生存质量的提高。     

Resection of large vestibular schwannomas: facial nerve preservation in the context of surgical approach and patient-assessed outcome

OBJECT: Vestibular schwannoma surgery has evolved as new therapeutic options have emerged, patients' expectations have risen, and the psychological effect of facial nerve paralysis has been studied. For large vestibular schwannomas for which extirpation is the primary therapy, the goals remain complete tumor resection and maintenance of normal neurological function. Improved microsurgical techniques and intraoperative facial nerve monitoring have decreased the complication rate and increased the likelihood of normal to near-normal postoperative facial function. Nevertheless, the impairment most frequently reported by patients as an adverse effect of surgery continues to be facial nerve paralysis. In addition, patient assessment has provided a different, less optimistic view of outcome. The authors evaluated the extent of facial function, timing of facial nerve recovery, patients' perceptions of this recovery and function, and the prognostic value of intraoperative facial nerve monitoring following resection of large vestibular schwannomas; they then analyzed these results with respect to different surgical approaches. METHODS: The authors retrospectively reviewed a database of 67 patients with 71 vestibular schwannomas measuring 3 cm or larger in diameter. The patients had undergone surgery via translabyrinthine, retrosigmoid, or combined approaches. Clinical outcomes were analyzed with respect to intraoperative facial nerve activity, responses to intraoperative stimulation, and time course of recovery. Eighty percent of patients obtained normal to near-normal facial function (House-Brackmann Grades I and II). Patients' perceptions of facial nerve function and recovery correlated well with the clinical observations. CONCLUSIONS: Trends in the data lead the authors to suggest that a retrosigmoid exposure, alone or in combination with a translabyrinthine approach, offers the best chance of facial nerve preservation in patients with large vestibular schwannomas.     

Intraoperative facial electromyography and brainstem auditory evoked potential findings in microvascular decompression for hemifacial spasm: correlation with postoperative delayed facial palsy

Background: Delayed facial palsy (DFP) after microvascular decompression (MVD) in patients with hemifacial spasm (HFS) is not uncommon, but the cause remains unknown. Objectives: To assess whether intraoperative electromyography (EMG) and brainstem auditory evoked potential (BAEP) can predict DFP after MVD. Methods: Between September 2009 and February 2011 we examined 86 patients, 9 of whom (10.4%) developed DFP after MVD on the same side. All patients underwent MVD and were followed-up for a median period of 13 months (range 6-22). We retrospectively examined intraoperative facial EMG and BAEP findings using our MVD patients' registry. We excluded secondary HFS and immediate postoperative facial palsy after MVD in this study. We assessed the prevalence and clinical characteristics of DFP and compared EMG and BAEP findings between DFP and non-DFP groups. Results: All patients recovered completely, with a mean time to recovery of 37.8 days (range 22-57). There were no significant differences between DFP and non-DFP patients in terms of the amplitude and latency of intraoperative EMG and BAEP. Conclusion: The usefulness of intraoperative facial EMG and BAEP is limited and cannot predict DFP after MVD for HFS. We speculate that DFP after MVD is not associated with permanent nerve damage according to the EMG findings.     

The role of three-dimensional computed tomography in the management of maxillofacial trauma

Open reduction and internal fixation of facial fractures demand a detailed understanding of the three-dimensional pattern of injury. This is difficult if not impossible to obtain with present radiographic methods. The purpose of this study was to define the role of three-dimensional computerized tomography (3DCT) in surgical management of facial fractures. The two-part investigation: 1) compared the diagnostic accuracy of 3DCT with conventional CT and plain film studies; and 2) examined the clinical usefulness of 3DCT to surgeons. Twenty-four acute trauma patients suspected of having facial fractures were examined radiographically with analysis of every facial bone and specific facial regions. Particular attention was directed to the course of the fracture lines and the number, size, and displacement of fracture fragments. The surgeons were then asked to conceptualize the reported and the personally observed radiographic information and document their impressions on preprinted diagrams of the facial skeleton. They also completed questionnaires designed to indicate whether patient management would be influenced by the 3DCT. The radiographic findings were correlated with intraoperative observations. The 3DCT provided superior definition of fracture lines (especially horizontal) and the extent of comminution was better appreciated. This additional information improved the surgeons' ability to plan placement of interfragmentary wires and/or plates. Surgeons were also able to more accurately predict those patients requiring immediate bone grafting. Large, life-size 3D images of the facial skeleton made intraoperative conceptualization of the injury pattern easier. The accuracy of the 3DCT images corroborated the intraoperative findings in all cases. The following conclusions are offered: 1) The diagnosis of most mandibular fractures can be made equally well with conventional and 3DCT techniques. 2) Improved diagnosis of fracture lines and the specific patterns of comminution in midface fractures is made possible with 3DCT. 3) If open reduction and internal fixation is the mode of treatment, 3DCT is desirable because the added information makes preoperative planning more accurate and thereby facilitates surgical intervention.