3D-CA (assisted) navigation surgery-FESS-of the nose, paranasal sinuses and the scull base, with the use of computer assisted (CA)-RP (rapid prototyping) models (3D-CA-RP-FESS)
Dg. Rhinosinuitis chronica purulenta (frontalis, ethmoidalis ant/post et maxillaris lateris sinistri; meningocele sinus frontalis lateris sinistri susp.). Hypertrophia tertiae partis intermediae conhae nasalis inferioris lateris dextri et hypertrophia mucosae poli anterioris et caudae conhae nasalis inferioris lateris sinistri.
Op.: Operatio sinus paranasales lateris sinistri per viam 3D-CA-RP-endoscopicam (3D-CA-FESS). Turbinotomia conharum nasalis inferioris bilateralis / diminuitio (tertiae partis intermediae) mucosae conharum nasalis inferioris bilateralis.
The mode of computer visualization of anatomic structures of the human body used to date could only provide diagnostic information and possibly assist in the preoperative preparation. Intraoperative use of computer generated operative field 3D-model has not been widely adopted to date. The intraoperative use of computer in real time requires development of appropriate hardware and software to connect medical instrumentarium with the computer, and to operate the computer by thus connected instrumentarium and sophisticated multimedia interfaces. Use of the latest program systems enables development of 3D spatial models, exploration in various projections, simultaneous presentation of multiple model sections and, most important, model development according to open computer standards (Open Inventor). Such a preoperative preparation can be applied in a variety of program systems that can be transmitted to distant collaborating radiologic and surgical work sites for preoperative consultation as well as during the operative procedure in real time (telesurgery, tele-FESS). Advanced technologies of exploring 3D spatial models allow for simulation of endoscopic surgery and planning the course of the future procedure (Virtual Endoscopy) or telesurgery (Tele-Virtual Endoscopy). By entering the models and navigating through the operable regions the surgeon becomes aware of the problems he will encounter during the real operation. In this way, preparation for the operation could be done including identification of the shortest and safest mode for the real operation to perform. The use of computer during a surgery/telesurgery requires highly reliable, stable and fast computer systems. During the procedure, the surgeon can operate the computer system by his voice (Voice Navigation). Model movements on the monitor, various projections and sections can be obtained by simple and short voice instructions during the surgery. On initial computer aided operative procedures, spatial orientation within the operative field of a 3D computer model and transfer of the particular point to the real operative field of the patient were performed by arbitrary approximation of the known reference points of the operative field anatomy. In this way, the given entities were recognized on the model and in the real operative field. The use of 3D spatial model of the operative field during the surgery has pointed to the need of positioning the tip of the instrument (endoscope, forceps, etc.) within the computer model. The major problem is transmission of the real patient operative field co-ordinate system to the co-ordinate system of the computer 3D spatial model of the same patient, which has been previously designed from a series of CT images during preoperative preparation.
46-year-old male with chronic sinusitis and the shadow intensity characteristic of a mucocele in the righr orbital space and ethmoids, was examined as the first case. MSCT (Siemens, 64 multislice) of the sinuses in coronal, sagital and axial sections demonstrated a disease of the ethmoidal infundibulum on the right side, with homogenous opacification and/or retention in the region of the right anterior and posterior ethmoidal cells and the orbit, as well as frontal sinus, with sphenoidal and the maxillary sinuses of normal transparency. MSCT scanning of the orbit revealed a tumor like shadow, which partially protruded into the anterior and posterior ethmoidal cells, and partially into the orbit. The medial wall of the orbit, right medial rectus muscle, optic nerve and the eyeball was displaced laterally (exophthalmos). A huge inferior turbinate was noticed on the right. Pronounced also chronic inflammatory changes with signs of ostiomeatal block were observed in the region of surrounded ethmoidal cells and frontal sinus. Patient also complained of difficulty breathing easily, with additional headaches in the right fronto-ethmoidal region, and recurrent sinusitis with postnasal dripping (appropriate nasal discharge/rhinosecretion). Visual function was partially reduced on the right eye, with normal finding on the left eye. Postoperatively, antibiotic therapy with local corticosteroids was prescribed. During the diagnostic process, we used the standard 2D-MSCT-imaging sections, virtual endoscopy of the patient’s head model over a few applied travel sections through patient's “virtual” head. Physical RP-models of patient’s head showed a clear demarcation (anatomic position) between the diseased and healthy tissues in the projection of the nose, paranasal sinuses and orbit. The patient underwent imageguided-CA-VE-FESS. Three months after the surgery, the patient was symptom-free. Generaly speaking, in this case, RP-approach proved efficient not only for the diagnostic purpose of the localization of the tumor shadow, and its identification within the orbital area, but also during the operation itself.
Figure 1. RP-model (back view) of the pathologic tissue and sinuses showed chronic
rhinosinusitis with homogenous transparency of all anatomical spaces
of the whole frontal sinus, anterior and posterior ethmoidal cells, and maxillary sinus
Figure 2. It is very easily to apply the minimum invasive traumatic
approach to all sinus cavities, keeping in mind the safety of patients
and the feasibility of the operation (several hours of postoperative
hospital stay of patient, with rapid recovery after surgery (3 days)
Figure 3. MSCT of the nose and paransal sinuses, prior the operation
(fist line), and MRI of the same region (postoperatively)
Figure 4. We performed VE of paranasal sinuses, and nasal cavity, as a part of diagnostic or preoperative management.