Учебники / Computer-Aided Otorhinolaryngology-Head and Neck Surgery Citardi 2002

FIGURE 2.3 The ISG Viewing Wand (ISG Technologies, Mississauga, Ontario, Canada) uses an arm-based tracking system. The patient’s head must be securely locked into position.

[15]. Using CT scans of 1–2 mm slices, the optical encoder rigid arm had an accuracy of 1 mm in 21 orbital surgeries. The authors felt that the added benefit of orientation outweighed the extra computer registration time and negligible additional operative time.

In 1994 and 1995, other investigators also reported on their experiences with some of the computer-guided systems described above [16–19].

2.3COMPUTER-AIDED SURGERY IN OTOLARYNGOLOGY

The first experiments using computer-aided surgery (CAS) in the field of otolaryngology were performed at the Aachen University of Technology and the Aachen University Hospital in Germany. In 1986, a group of Aachen investigators described their experience with an industrial passive robot arm (Figure 2.4) [20]. The segments of this arm were connected via five rotary joints. Rotary

FIGURE 2.4 Professor G. Schlo¨ndorff demonstrates the use of an early Aachen CAS system.

analog potentiometers measured the joint movements and relayed information about the position of the end of the arm to a computer. Hardware and software components were developed to use this robot arm for intraoperative position detection. However, since this device was developed for applications in industry, its handling was cumbersome and its relative inaccuracy (margin of accuracy 3 mm) was judged insufficient for otolaryngological procedures.

Aachen investigators conducted further research on a counterbalanced sixjointed optical encoder unit linked to a dedicated 68008-microprocessor connected to a main computer. Two-dimensional (2D) data from a preoperative CT scan (2 mm thick slices) were first ‘‘merged’’ to form a 3D cubic ‘‘voxel model’’ with x, y, and z coordinates. This model was displayed on a monitor, along with the original axial (x, y) CT image and the reconstructed coronal (x, z) and sagittal (y, z) views. Four radiopaque reference points were placed on the patient’s face before the preoperative CT scan. At surgery, each reference point as visualized on the computer monitor was correlated with the corresponding reference point marked on the patient’s face by touching the point with the tip of the digitizer

arm. Once all four points were entered, the computer could take any other point on/in the patient (when touched by the tip of the digitizing arm) and match it to the same point on the CT images as displayed on the monitor (shown by a crosshair). This system was used in 64 patients for surgery of the paranasal sinuses, orbit, and skull base, as well as the surgical treatment of central nervous system lesions and lesions within the pterygopalatine fossa. The authors felt that surgery with this CAS platform, which had an accuracy of 1–2 mm, was safer than unaided surgery.

In 1991, the Aachen group updated their experiences in a report on 200 surgical procedures [21]. The indications for CAS were nasal, paranasal sinus, and orbital tumors, skull base procedures, primary and revision paranasal sinus surgery, and acoustic neuromas. The authors also evaluated the risks and benefits of CAS. The risks included extra radiation from the additional CT scan required for the 3D model and the expense of equipment and additional manpower. They noted, however, that the extra radiation dose was minimal and far below the 50% cataract dose. The benefit of CAS was the dramatic increase in surgical information, which led to more efficient surgery and a reduction in operative risks.

Krybus et al. [22], also from Aachen, described the development of an infrared optical localizing probe in 1991. With the infrared free arm, sensors could be attached directly to the operating instruments. Five infrared-emitting diodes were positioned on the handle of an instrument, with three diodes distal to the handle tip and two diodes proximal to it. The distance between these emitters provided for large angles of infrared radiation. Infrared emitters were also attached to the patient. Three sensing cameras were suspended in a circular array 800–1200 mm above the operating table. The position of the instrument tip was located by triangulation calculations based on the known geometry of the infrared diodes on both the instrument and the patient relative to the sensing cameras. The optical localizer took seven measurements per second with a reported accuracy of 1.5 mm. The initial infrared localizing system has since been upgraded.

In 1993, Aachen investigators Mo¨sges and Klimek reported on the application of computer assistance during paranasal sinus surgery [23]. They believed that CAS systems provided helpful intraoperative orientation, especially when there was bleeding or when landmarks were obliterated by tumor or prior surgery. The CT parameters in this report were 1 or 2 mm slice thickness; continuous, nonoverlapping slices; and transverse slices (which avoided dental amalgams). The authors concluded that CAS would reduce the reported 2% complication rate associated with endonasal surgery.

In 1994 Anon et al. published the first report of computer-aided endoscopic sinus surgery in the United States [24]. The ISG Viewing Wand with a 6-inch neuroprobe was utilized in 70 procedures. Using a combination of landmark reg-

istration and surface-fitting registration (instead of fiducial marker registration), the authors reported an observed clinical accuracy of 1–2 mm. The indications for CAS included revision cases, massive disease, sphenoid sinus pathology, anomalies such as an Onodi cell, and frontal recess disease.

Carrau et al. also used the Viewing Wand to compare the standard 6-foot Caldwell template with computer guidance for external frontal sinusotomy [25]. The indications for obliteration were frontal sinus fracture (including the frontal recess), severe trauma from a gunshot wound, and chronic frontal sinusitis. The patient’s head was secured in a head holder, and registration was performed on landmarks or previously placed fiducial markers. Following exposure of the frontal bone via a bicoronal flap, the 6-foot Caldwell template was placed in position and marked. The Viewing Wand was then used to outline the frontal sinus. The differences between the two techniques ranged from 0 to 1.75 cm (the larger the sinus, the larger the difference). Following the osteotomies, direct visualization into the sinuses showed that the Viewing Wand was more accurate and that penetration into the cranial cavity would have occurred in four of six cases if the template alone had been used.

Gunkel et al. reported on their experiences with the Viewing Wand and the Virtual Patient (ARTMA, Austria), which utilized an electromagnetic digitizer [26]. The transmitter was placed close to the patient’s head, and the sensor was attached to various surgical instruments and/or an endoscope. A unique feature of the Virtual Patient system was the ability to decide on the surgical trajectory by marking specific areas on the displayed CT scans along the planned course of surgery. During the operation, colored rectangular frames (representing the trajectory) were superimposed onto the endoscopic view seen on the monitor, thus forming a ‘‘highway’’ for the surgeon to follow. An accuracy of 1.0–2.5 mm was reported for the Viewing Wand. The Virtual Patient system was also quite accurate.

In 1995, Anon et al. updated their experiences with the arm-based Viewing Wand and also introduced the FlashPoint Model 5000 3-D Optical Localizer (Image-Guided Technologies, Boulder, CO) (Figure 2.5) [27]. The latter system used a probe fitted with light-emitting diodes, as well as a dynamic reference frame with three diodes affixed in a triangular arrangement. Unlike the Viewing Arm, which is self-referential and does not tolerate patient motion, the infrared localizer could be used while the patient was under either general or local anesthesia.

In 1996, Tebo et al. repeated their accuracy study on a Plexiglas phantom and a plastic skull, using the FlashPoint system (in place of the Viewing Wand) [28]. In this study, 500 measurements were made on the Plexiglas phantom, and 1590 points were evaluated on the plastic skull. The average error was in the range of 2–3 mm, with 95% of the errors ranging from 0 to 5 mm. In three

FIGURE 2.5 The Flashpoint 5000 (Image-Guided Technologies, Boulder, CO) uses an active infrared technology.

operations performed by three different surgeons, clinical accuracy ranged from 2 to 5 mm. The authors noted that better hardware, coupled with software improvements, should result in greater accuracy.

Fried et al. [29] published work on an electromagnetic localizer, the InstaTrak system (Visualization Technology Inc., Lawrence, MA) (Figure 2.6). This unit couples electromagnetic tracking to either straight or curved aspirators. With the InstaTrak, no intraoperative complications were encountered in 14 surgical cases. The system was easily integrated into the operating room setting. While complete analysis of the data was deferred until completion of a multisite study, a secondary study using cadaver dissection reported an accuracy of within 2 mm. The authors concluded that the InstaTrak system had overcome many of the limitations of other computer-guided methods.

In 1999, Klimek et al. presented their laboratory and intraoperative findings on a new type of optical computer-aided surgery [30]. The VectorVison (BrainLAB, Heimstetten, Germany) uses passive reflective optical markers for coordinate determination (Figure 2.7). Laboratory accuracy measurements were ob-

FIGURE 2.6 The InstaTrak (Visualization Technology, Lawrence, MA) was the first commercially available system that used electromagnetic tracking for otolaryngology.

tained on a Plexiglas model with known coordinates. Intraoperative accuracy measurements were recorded from 24 patients undergoing endonasal sinus surgery with two different referencing techniques (fiducial markers and mouthpiece). The system demonstrated laboratory accuracy within 0.86 mm (SD 0.94 mm). Intraoperative accuracy was within 1.14 mm (SD 0.57 mm) (fiducial markers) and 2.66 mm (SD 1.89 mm) (mouthpiece) (p 0.05). One of the main advan-

FIGURE 2.7 The VectorVision (BrainLAB, Heimstetten, Germany) utilizes passive infrared tracking technology.

tages of the new technology was the possibility of using any common instrument by attaching the reflective array.

The impact of CAS in the clinical setting was studied by Metson et al. in a combined prospective case study and retrospective analysis of physician surveys [31]. The LandmarX, an active optical-based CAS system (Medtronic

Xomed, Jacksonville, FL) was used by 34 physicians to perform 754 sinonasal surgeries over a 2.5-year period at Massachusetts Eye and Ear Infirmary (Figure 2.8). The measured accuracy of anatomical localization at the start of surgery showed a mean value of 1.69 0.38 mm. According to a majority of surgeons questioned, use of the CAS equipment increased operating room time by 15–30 minutes during initial cases and by 5–15 minutes after experience with the equipment had been acquired. More than 90% of their surgeons anticipated the contin-

FIGURE 2.8 The LandmarX (Medtronic Xomed, Jacksonville, FL) uses active infrared tracking for surgical navigation.

ued use of CAS equipment for sinus surgery at a similar or greater level in the future.

2.4 TERMINOLOGY

In 1985, Georg Schlo¨ndorff coined the term computer-assisted surgery. At that time, fully automatic robotic systems had been developed for industrial applications and were already in use in areas such as automobile production. Schlo¨ndorff’s aim was to give the surgeon a ‘‘computerized assistant’’ that would give additional information during the surgical process, but not replace the human surgeon.

Since 1985, numerous terms—including image-guided surgery (IGS)— have been applied to this discipline. Currently, IGS is commonly used in descriptions of computer-based surgical navigation systems for sinus surgery. In addition, various corporate trademarks are often mentioned.

Today, however, the term computer-aided surgery is the most appropriate term for the entire discipline, which includes surgical navigation, computerenabled CT/MR review, Internet-based medicine, and surgical robotics. In 1997, an international group of experts chose to incorporate the ‘‘computer-aided surgery’’ terminology (rather than ‘‘computer-assisted surgery’’ or IGS) in the name for a new society dedicated to this area when they formed the International Society for Computer-Aided Surgery (ISCAS).

2.5 CONCLUSION

The history of computer-aided sinus surgery is rewritten every day due to the rapid development of new innovations in hardware and improvements in software. Luxenberger et al. [32] summarized the current status of computer-aided surgery for otolaryngology: CAS ‘‘is increasingly acknowledged as useful technology also for endoscopic sinus surgery.’’ They further concluded that CAS is a significant development in sinus surgery. Often CAS is depicted as a replacement for other aspects of the surgical care of patients; however, it should be emphasized that CAS should be considered a helpful surgical tool.

REFERENCES

1.Bergstrom M, Greitz T. Stereotaxic computed tomography. Am J Roentgenol 1976; 127:167–170.

2.Brown R. A computerized tomography-computer graphics approach to sterotaxic localization. J Neurosurg 1979; 50:715–720.

3.Perry JH, Rosenbaum AE, Lunsford LD, et al. Computed tomography-guided stereo-

tactic surgery: conception and development of a new stereotactic methodology. Neurosurgery 1980; 7:376–381.

4.Roberts DW, Strohbehn JW, Hatch JF, et al. A frameless stereotaxic integration of computerized tomographic imaging and the operating microscope. J Neurosurg 1986; 65:545–549.

5.Watanabe E, Watanabe T, Manaka S, et al. Three-dimensional digitizer (Neuronavigator): new equipment for computed tomography-guided sterotaxic surgery. Surg Neurol 1987; 27:543–547.

6.Reinhardt H, Meyer H, Amrein E. A computer-assisted device for the intraoperative CT-correlated localization of brain tumors. Eur Surg Res 1988; 20:51–58.

7.Guthrie BL, Adler JR. Frameless stereotaxy computer interactive neurosurgery. Perspect Neurol Surg 1991; 2:1–15.

8.Watanabe E, Mayanagi Y, Kosugi Y, et al. Open surgery assisted by the Neuronavigator, a stereotactic articulated, sensitive arm. Neurosurgery 1991; 28:792–800.

9.Kato A, Yoshimine T, Hayakawa T, Tomita Y, Ikeda T, Mitomo M, Harada K, Mogami H. A frameless, armless navigational system for computer-assisted neurosurgery [technical note]. J Neurosurg 1991; 74:845–849.

10.Leggett WB, Greenberg MM, Gannon WE, et al. The Viewing Wand: a new system for three-dimensional computed tomography-correlated intraoperative localization. Curr Surg 1991; 48:674–678.

11.Zinreich SJ, Tebo SA, Long DM, et al. Frameless stereotaxic integration of CT imaging data: accuracy and initial applications. Radiology 1993; 188:735–742.

12.Laborde G, Gilsbach J, Harders A, Klimek L, Moesges R, Krybus W. Computer assisted localizer for planning of surgery and intra-operative orientation. Acta Neurochir 1992; 119:166–170.

13.Barnett GH, Kormos DW, Steiner CP, Weisenberger J. Intraoperative localization using an armless, frameless stereotactic wand. Technical note. J Neurosurg 1993; 78:510–514.

14.Barnett GH, Kormos DW, Steiner CP, Weisenberger J. Use of a frameless, armless stereotactic wand for brain tumor localization with two-dimensional and threedimensional neuroimaging. Neurosurgery 1993; 33:674–678.

15.Klimek L, Wenzel M, Mo¨sges R. Computer-assisted orbital surgery. Ophthalmic Surg 1993; 24:411–417.

16.Murphy MA, Barnett GH, Kormos DW, et al. Astrocytoma resection using an interactive frameless stereotactic wand: an early experience. J Clin Neurosci 1994; 1: 33–37.

17.Kormos DW, Piraino DW. Image-guided surgery attains clinical status. In: Diagnostic Imaging. San Francisco: Miller Freeman Inc., 1994.

18.Pollack IF, Welch W, Jacobs GB, Janecka IP. Frameless stereotactic guidance. An intraoperative adjunct in the transoral approach for ventral cervicomedullary junction decompression. Spine 1995; 20:216–220.

19.Kondziolka D, Lunsford LD. Guided neurosurgery using the ISG Viewing Wand. Contemp Neurosurg 1995; 17:1–6.

20.Schlondorff G, Mosges R, Meyer-Ebrecht D, Krybus W, Adams L. CAS (computer assisted surgery). A new procedure in head and neck surgery. HNO 1989; 37:187– 190.