Intraoperative computed tomography in otorhinolaryngology

Intraoperative Handheld Digital X-ray for Assessment of Intracochlear Positioning of Electrode Arrays in Recipients of Cochlear Implants

Objectives: This study aims to evaluate the practicality of handheld digital X-ray in determining the position of the electrode array following Cochlear implantation (CI). Methods: A retrospective study was conducted involving 11 patients (12 ears) who underwent intraoperative imaging via handheld X-ray (MINE ALNU®, OTOM, Gwangju, South Korea) post-CI between December 2021 and January 2023. Immediate confirmation of the correct electrode array placement in the cochlea was achieved, with subsequent comparisons made to C-arm image and postoperative transorbital view X-ray. Results: Rapid intraoperative imaging was achieved in all instances. The electrode types used included 9 Nucleus slim modiolar electrodes, 1 Nucleus contour electrode, and 2 Medel flex26 electrodes. A malpositioned electrode array was detected in one patient. The handheld digital X-ray also adeptly visualized the electrodes implanted in pediatric patients. Conclusions: The use of intraoperative handheld digital X-ray using MINE ALNU® proves to be a safe, efficient, straightforward, and reliable method for immediate identification of an inserted electrode array. It has potential to replace the traditional C-arm X-ray for verifying electrode positioning in the operating room.

Intraoperative Imaging Techniques to Improve Surgical Resection Margins of Oropharyngeal Squamous Cell Cancer: A Comprehensive Review of Current Literature

Inadequate resection margins in head and neck squamous cell carcinoma surgery necessitate adjuvant therapies such as re-resection and radiotherapy with or without chemotherapy and imply increasing morbidity and worse prognosis. On the other hand, taking larger margins by extending the resection also leads to avoidable increased morbidity. Oropharyngeal squamous cell carcinomas (OPSCCs) are often difficult to access; resections are limited by anatomy and functionality and thus carry an increased risk for close or positive margins. Therefore, there is a need to improve intraoperative assessment of resection margins. Several intraoperative techniques are available, but these often lead to prolonged operative time and are only suitable for a subgroup of patients. In recent years, new diagnostic tools have been the subject of investigation. This study reviews the available literature on intraoperative techniques to improve resection margins for OPSCCs. A literature search was performed in Embase, PubMed, and Cochrane. Narrow band imaging (NBI), high-resolution microendoscopic imaging, confocal laser endomicroscopy, frozen section analysis (FSA), ultrasound (US), computed tomography scan (CT), (auto) fluorescence imaging (FI), and augmented reality (AR) have all been used for OPSCC. NBI, FSA, and US are most commonly used and increase the rate of negative margins. Other techniques will become available in the future, of which fluorescence imaging has high potential for use with OPSCC.

Perspective review on applications of optics in skull base surgery

The use of optic technology in skull base surgeries has the potential to revolutionize the field of medicine, particularly neurosurgery and neurology. Here, we briefly present the past, present, and future of skull-base surgery, with an emphasis on the applications of optical topography techniques. We discuss optical topography techniques such as functional near-infrared spectroscopy, optical diffusion tomography, and optical topographical imaging. Optical topography techniques are particularly advantageous when combined with other imaging methods. For instance, optical topography can be combined with techniques such as functional magnetic resonance imaging (fMRI) to combine the temporal resolution of optical topography with the spatial resolution of fMRI. Multimodal approaches will be critical to advance brain-related research as well as medicine. Structured light imaging techniques are also writing the future of 3-dimensional imaging. In short, optical topography can allow for non-invasive, high-resolution imaging that will provide real-time visualizations of the brain that are ideal for neurosurgery. From the limitations of traditional skull base surgeries to the newest developments in optical neuroimaging, here we will discuss the potential applications of optics in skull base procedures.

Mobile computed tomography : three year clinical experience in Korea

Objective

Obtaining real-time image is essential for neurosurgeons to minimize invasion of normal brain tissue and to prompt diagnosis of intracranial event. The aim of this study was to report our three-year experience with a mobile computed tomography (mCT) for intraoperative and bedside scanning.

Methods

A total of 357 mCT (297 patients) scans from January 2009 to December 2011 in single institution were reviewed. After excluding post-operative routine follow-up, 202 mCT were included for analysis. Their medical records such as diagnosis, clinical application, impact on decision making, times, image quality and radiologic findings were assessed.

Results

Two-hundred-two mCT scans were performed in the operation room (n=192, 95%) or intensive care unit (ICU) (n=10, 5%). Regarding intraoperative images, extent of resection of tumor (n=55, 27.2%), degree of hematoma removal (n=42, 20.8%), confirmation of catheter placement (n=91, 45.0%) and monitoring unexpected complications (n=4, 2.0%) were evaluated. A total of 14 additional procedures were introduced after confirmation of residual tumor (n=7, 50%), hematoma (n=2, 14.3%), malpositioned catheter (n=3, 21.4%) and newly developed intracranial events (n=2, 14.3%). Every image was obtained within 15 minutes and image quality was sufficient for interpretation.

Conclusion

mCT is feasible for prompt intraoperative and ICU monitoring with enhanced diagnostic certainty, safety and efficiency.

Intraoperative CT-guided cochlear implantation in congenital ear deformity

CONCLUSIONS

Intraoperative computed tomography (iCT)-guided cochlear implantation is practical and effective for correct electrode placement in the cochlea of patients with congenital inner ear and/or complex middle ear malformation.

OBJECTIVES

The operation in patients with inner ear and/or complex middle ear malformation including abnormal facial nerve course is difficult. This study evaluated the efficacy of cochlear implantation under the guidance of iCT to insure correct electrode placement.

METHODS

This was a prospective interventional case series. Ten patients with severe to profound sensorineural hearing loss due to ear malformations were enrolled, and iCT was used to confirm the right placement of electrodes.

RESULTS

Intraoperative CT was performed three times in one patient, twice in two, and once in the others. Interruption of the surgical process for each iCT until resumption of surgery was 9.64 ± 0.63 min. iCT revealed incorrectly positioned cochlear implants in two patients, which were immediately corrected. There were no reoperations due to misplacement of electrodes. iCT helped locate the cochlea in the middle ear of one patient with an abnormal facial nerve course. The overall intervention rate based on iCT findings was 30%.

LEVEL OF EVIDENCE

level 4.

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.

Prospective evaluation of intraoperative computed tomography imaging for endoscopic sinonasal and skull-base surgery

BACKGROUND

The objective of this study was to prospectively evaluate the clinical impact of intraoperative computed tomography (CT) imaging on endoscopic sinonasal and skull base procedures.

METHODS

A total of 49 patients were enrolled after informed consent from December 2009 to May 2010. Patients underwent intraoperative volume CT imaging (xCAT, Xoran Technologies, Ann Arbor, MI) at the conclusion of their proposed surgery.

RESULTS

The mean age was 48.6 years with male:female ratio of 1.3:1. Surgical procedures included revision or primary endoscopic sinonasal surgery (ESS) (36), endoscopic benign or malignant tumor resection (10), endoscopic mucocele drainage (2), and endoscopic tumor biopsy (1). The mean Lund-Mackay (L-M) score was 10.6 (range 1-21). The indications for intraoperative imaging included extent of paranasal sinus dissection in 38 (77.6%), extent of tumor resection in 11 (22.4%), adequacy of mucocele drainage in 3 (6.1%), and frontal stent position in 2 (4.1%) cases. Average acquisition time was 5.3 minutes. The CT acquisition quality was deemed excellent in 24 (49.0%), good in 15 (30.6%), fair in 5 (10.2%), and unattainable in 5 (10.2%) cases. Additional interventions were performed in 8 of 44 cases (18%) based on the intraoperative CT dataset. Analysis of predictive factors for additional intervention, including presence of polyps, presence of tumor, previous surgery, use of image guidance, and CT quality did not reach statistical significance.

CONCLUSION

Intraoperative CT scanning may hold important utility in selected endoscopic sinonasal and skull base procedures with additional interventions being performed in 18% of cases. The present study was unable to identify specific factors that would preoperatively predict the need for intraoperative imaging. Future clinical trials should include a multi-institutional design to better delineate these important variables.

Features of cranio-maxillofacial trauma in the massive Sichuan earthquake: analysis of 221 cases with multi-detector row CT

OBJECTIVE

In a massive earthquake, cranio-maxillofacial trauma was common. The present study was to determine the features of cranio-maxillofacial trauma sustained in the massive Sichuan earthquake by multi-detector row computed tomography (MDCT).

METHODS

The study included 221 consecutive patients (123 males and 98 females; age range, 1-83 years; median age, 35 years) with cranio-maxillofacial trauma in the Sichuan earthquake, who underwent cranio-maxillofacial MDCT scans. The image data were retrospectively reviewed focusing on the injuries of the cranio-maxillofacial soft tissue, facial bones and cranium.

RESULTS

All patients had soft tissue injuries frequently with foreign bodies. Ninety-seven (43.9%) patients had fractures (1.5 involved sites per patient, range from 1 to 8) including single cranial fractures in 36 (37.1%) cases, single maxillofacial fractures were seen in 48 (49.5%) and cranio-maxillofacial fractures in 13 (13.4%). Single bone fracture was more common than multiple bone fractures (p<0.05). Nasal, ethmoid bones and the orbits were the most commonly involved sites of the craniofacial region. Thirty-eight (17.2%) patients had intracranial injuries, the commonest being subarachnoid haemorrhage and the commonest sites were the temporal and frontal regions. Coexisting intracranial injuries were more common in patients with cranial fractures than in patients with maxillofacial fractures (p<0.05).

CONCLUSION

Our results indicate that the cranio-maxillofacial trauma arising from the massive Sichuan earthquake had some characteristic features, and a significant number of individuals had the potential for combined cranial and maxillofacial injuries, successful management of which required a multidisciplinary approach.

Mobile computed tomography : early experience in Korea

OBJECTIVE

With improved technology, the values of intraoperative computed tomography (iCT) have been reevaluated. We describe our early clinical experience with a mobile CT (mCT) system for iCT and discuss its clinical applications, advantages and limitations.

METHODS

Compared with intraoperative magnetic resonance imaging, this mCT system has no need for major reconstruction of a preexisting operating room for shielding, or for specialized instruments or equipment. Patients are placed on a radiolucent head clamp that fits within the gantry. Because it consists simply of a scanner and a workstation, it can be moved between locations such as an operating room, an intensive care unit (ICU) or an emergency room without difficulty. Furthermore, it can achieve nearly all types of CT scanning procedures such as enhancement, temporal bone imaging, angiography and three-dimensional reconstruction.

RESULTS

For intracranial surgery, mCT can be used for intraoperative real-time neuronavigation by interacting with preoperative images. It can also be used for intraoperative confirmation of the extent of resection of intracranial lesions and for immediate checks for preventing intraoperative unexpected accidents. Therefore, the goals of maximal resection or optimal treatment can be achieved without any guesswork. Furthermore, mCT can achieve improved patient care with safety and faster diagnosis for patients in an ICU who might be subjected to a ventilator and/or various monitoring devices.

CONCLUSION

Our initial experience demonstrates that mCT with high-quality imaging offers very useful information in various clinical situations.

Error analysis for determination of accuracy of an ultrasound navigation system for head and neck surgery

OBJECTIVE

The use of conventional CT- or MRI-based navigation systems for head and neck surgery is unsatisfactory due to tissue shift. Moreover, changes occurring during surgical procedures cannot be visualized. To overcome these drawbacks, we developed a novel ultrasound-guided navigation system for head and neck surgery. A comprehensive error analysis was undertaken to determine the accuracy of this new system.

MATERIALS AND METHODS

The evaluation of the system accuracy was essentially based on the method of error definition for well-established fiducial marker registration methods (point-pair matching) as used in, for example, CT- or MRI-based navigation. This method was modified in accordance with the specific requirements of ultrasound-guided navigation. The Fiducial Localization Error (FLE), Fiducial Registration Error (FRE) and Target Registration Error (TRE) were determined.

RESULTS

In our navigation system, the real error (the TRE actually measured) did not exceed a volume of 1.58 mm(3) with a probability of 0.9. A mean value of 0.8 mm (standard deviation: 0.25 mm) was found for the FRE. The quality of the coordinate tracking system (Polaris localizer) could be defined with an FLE of 0.4 +/- 0.11 mm (mean +/- standard deviation). The quality of the coordinates of the crosshairs of the phantom was determined with a deviation of 0.5 mm (standard deviation: 0.07 mm).

CONCLUSION

The results demonstrate that our newly developed ultrasound-guided navigation system shows only very small system deviations and therefore provides very accurate data for practical applications.

Intraoperative computed tomography and automated registration for image-guided cranial surgery

OBJECTIVES

Two key problems for the use of navigation systems in image-guided surgery are accurate patient-to-image registration and the fact that with ongoing surgery the patient's anatomy is altered while the image data remains unchanged. A system for intraoperative CT imaging and fully automated registration of this image addresses both problems. It had been evaluated successfully in phantom studies. In this clinical study, we assessed the impact of the system on intraoperative workflow and registration accuracy in everyday patient care.

METHODS

In ten patients who underwent image-guided surgery, CT image data were acquired intraoperatively and were automatically registered in the navigation system. Registration accuracy and surgical outcome were assessed clinically. In six of these patients, a maxillary splint with markers had been inserted to cross-check registration accuracy. The target registration error of these markers was measured.

RESULTS

In all cases, registration accuracy was clinically sufficient and the surgical task could be performed successfully. In those cases where a maxillary template with target markers was attached for additional control of the registration accuracy, the target registration error was always better than 2 mm. Automated registration reduced the intraoperative registration time considerably and partially compensated for the time needed to perform the image data acquisition.

CONCLUSIONS

Intraoperative CT imaging and automated registration successfully address the two key problems of image-guided surgery. The method is robust and accurate and proved its usability in everyday patient care.

Navigation-supported and sonographically-controlled fine-needle puncture in soft tissues of the neck

In surgery, sonography has been a well-accepted means of orientation for years. The immediate vicinity of many vital structures in the head and neck region calls for a very exact visualization of the surgical instrument in the 2-D ultrasonic picture. We report on the development of a new method for navigation-supported and sonographically-controlled fine-needle puncture in soft tissues of the neck. Our system comprises a navigated ultrasound probe, a navigated fine-puncture needle and a coordinate sensor. A personal computer with specially-developed software assists calibration and surgical application. The applicability test for the system is described. In vitro, a model lymph node of 9 mm in diameter had been hit. It is shown that the target structure can be aimed at very precisely by the navigated puncture needle. An accuracy of 97% and a specificity of 99% could be demonstrated. The development of a very precise and easy-to-handle method for navigation-supported fine-needle puncture in the neck region is presented. The outstanding advantage of this method is that no rigid reference gadget fixed to the patient's body is necessary. That makes this method very suitable for surgery in the neck region. Contrary to other sonographically-supported navigation methods in the head and neck region, preoperative imaging (CT or MRT) is dispensable.

[Navigation-assisted sonography for soft tissues in the head and neck region]

BACKGROUND

In soft tissue surgery of the head and neck region tissue shifts limit the usefulness of conventional CT/MRI-based navigation procedures. Furthermore, changes caused by invasive measures cannot be visualized.

METHODS

A novel navigation device for sonography of soft tissues was developed. This consists of a navigated ultrasound scanner, a navigated surgical instrument, and a personal computer with custom-made software. Its use makes an additional visualization by means of CT or MRI dispensable.

RESULTS

The system deviation (three-dimensional error) of this newly developed prototype was less than 1 mm. The practical application in a model setup showed good handling properties of the system. Orientation and approach of the surgical instrument to the sonographically visualized target structure were rapid and accurate.

CONCLUSION

This new navigation system does not require additional CT or MRI images. The navigated ultrasound probe shows tissue changes in real time. This navigation system is especially suitable for invasive procedures in soft tissues.

Clinical Utility of Intraoperative Volume Computed Tomography Scanner for Endoscopic Sinonasal and Skull Base Procedures

Background

Intraoperative surgical navigation has become widely accepted as an important tool for improvement of surgical outcomes and reduction of complication in endoscopic sinus surgery (ESS). The purpose of this study was to assess the clinical utility of intraoperative volume computed tomography (CT) scanning in endoscopic sinonasal and skull base procedures.

Methods

Retrospective review of patients who underwent intraoperative volume CT imaging (xCAT; XoranTechnologies, Ann Arbor, MI) during endoscopic sinonasal and skull base surgery during a 3-month period was performed. Intraoperative, computer-enabled triplanar review of reformatted 0.4-mm images was performed in all cases.

Results

Intraoperative volume CT scanning was completed in 25 patients. Surgical procedures included revision/primary ESS for chronic rhinosinusitis (CRS) with or without polyposis (12 cases) and mucoceles (6 cases) as well as endoscopic neoplasm resection (5 cases), endoscopic fibro-osseous lesion resection (1 case), and endoscopic meningoencephalocele repair (1 case). The indications for intraoperative CT scanning included assessment of surgical dissection (23 cases), extent of tumor resection (6 cases), and frontal stent placement (6 cases). Based on the intraoperative volume CT information, additional interventions, including additional tumor resection (2 cases), dissection of ethmoid partitions (2 cases), frontal bone drilling during Draf IIB (1 case), and repositioning of a frontal stent (1 case) were performed in 6 (24%) cases.

Conclusion

Intraoperative volume CT scanning was successfully performed in 25 patients undergoing ESS. Because additional surgical intervention was performed in 24% of cases, this technology may have an important role in endoscopic sinonasal and skull base procedures.

Untersuchungen zum Entstehungsmechanismus der isolierten Orbitabodenfraktur

BACKGROUND

Isolated orbital floor fractures make up a significant proportion of all facial injuries, but the mechanism involved in these injuries to the orbital walls (blow-out fractures) has not yet been completely defined. Two theories have been described, which seem to be mutually exclusive. According to the hydraulic pressure theory, the kinetic energy of the blow is transferred via the incompressible eye tissue to the floor of the orbita, which in turn fractures. The buckling force theory, in contrast, explains these fractures as the result of bending and shear stresses arising from kinetic energy act directly on the orbital rim.

MATERIALS AND METHODS

With the aim of elucidating the mechanism of injury, we constructed a simplified finite-element model of the human orbita by 3D optical scanning of a human skull obtained after an autopsy examination. We created a generic approximation model based on empiric data derived from femoral fractures and reported in the literature. Several experiments were conducted to test both the above hypotheses by direct and indirect application of kinetic energy.

RESULTS

We simulated different types of shear stress with the finite-element model of the skull. The calculated points of maximum pressure were all within the orbital floor.

CONCLUSION

The simulation showed that both mechanisms can lead to fractures, as also documented by recent studies. The generation of a finite-element model and simulation of stresses were initially useful in establishing a method. More detailed studies on the empiric data relating to the various structures and more extensive determination and measurement of different skull and/or orbita geometries are needed before we can achieve a model in which the mechanical attributes of the structures involved are reproduced with closer approximation to the real-life situation.

Advances in imaging of the paranasal sinuses

Imaging technology has played a significant role in the diagnosis and management of sinonasal disorders. Plain sinus films are almost exclusively replaced by CT in the work-up for inflammatory sinus disease. MRI provides complementary information to CT in cases of sinonasal and skull-base neoplasms. The evolution of endoscopic surgical techniques for the paranasal sinuses and skull base is made possible by the parallel advancement of imaging technologies. Recent advances that are currently in clinical use have included multidetector row CT scanners and computer image-guidance systems for surgery. Three-dimensional CT angiography, image-guided CT-MR fusion, and intraoperative image-guidance are new techniques that are currently being evaluated. As imaging technology continues to advance, so does the capability to treat diseases beyond the sinuses and skull base with minimally invasive, endoscopic approaches.