CT-guided Stereotaxy Research Articles

Intracerebral Hemorrhage, Indication for Surgical Treatment and Surgical Techniques

Intracerebral hemorrhage is a common disease. We give a short review of primary haemorrhages under neurosurgical aspects. Neurological symptoms depend on localisation and size of the hematoma. Only a subgroup of intracerebral haemorrhages is treated surgically. The STICH-trial tried to differentiate, in which cases the hematoma should be removed surgically. Surgical treatment could be performed by open craniotomy, endoscopic evacuation of the hematoma or CT-guided stereotaxy.

Accuracy and diagnostic yield of CT-guided stereotactic liver biopsy of primary and secondary liver tumors

Objective: CT-guided biopsy still plays a decisive role in the management of liver tumors, especially if the lesions are not visible or accessible by ultrasound. As CT-guided stereotaxy appears to be a very accurate targeting technique, the aim of this study was to evaluate the targeting accuracy, diagnostic yield, and complications of CT-guided stereotactic liver biopsy of primary and secondary liver tumors.Methods and Materials: Prior to stereotactic liver biopsy, patients under general anesthesia were immobilized using a vacuum cushion. Respiratory motion was controlled by temporary disconnections of the endotracheal tube. An optical-based navigation system was used for 3D trajectory planning and placement of a 15-G coaxial needle via a stereotactic aiming device. The histological samples were obtained using a 16-G Tru-Cut™ biopsy needle system. For evaluation of targeting accuracy the control CT image with the needles in place was fused with the planning CT image. The lateral error at the tip and skin entry point and the angular error were calculated. In addition, the skin-to-liver-surface (SL) distance, the needle-to-liver-surface (NL) angle, and the presence of liver cirrhosis were evaluated. The diagnostic yield was evaluated by histological reports from the institutional pathologists.Results: The median lateral error was 2.5 mm (range: 0–6.5 mm) at the needle entry point and 3.2 mm (range: 0.01–9.4 mm) at the needle tip. The median angular error was 1.06° (range: 0–6.64°). Liver cirrhosis, NL angle and SL distance showed no significant impact on the targeting accuracy. Forty-five of the 46 liver biopsies (97.8%) were diagnostic according to the histological reports. No puncture-related complications such as bleeding or perforation of intestinal organs or lung tissue were recorded.

Targeting accuracy of CT-guided stereotaxy for radiofrequency ablation of liver tumours

The targeting accuracy during CT-guided stereotactic radiofrequency ablation (SRFA) of liver tumours was evaluated in a clinical study. Patients under general anaesthesia were immobilized using a vacuum cushion and respiratory motion control was based on temporary disconnections of the endotracheal tube. An optical-based navigation system was used for 3D trajectory planning and needle placement via a stereotactic aiming device. A control CT with the needles in place was fused with the planning CT for accuracy evaluation. Sub-analysis was performed for “location” (liver segments II – VIII), “approach” (intercostal or transabdominal), “properties” (clear parenchymal, subcapsular, subphrenic, fat, and subphrenic plus fat), and “path length”. In 20 patients with 35 liver lesions, a total of 145 needles were placed with mean (±SD) lateral errors of 3.6 ± 2.5 mm at the needle tip, angular errors of 1.3° ± 1.2°, and longitudinal errors at the needle tip of -7.4 ± 6.2 mm. No puncture-related complications were noted. No significant differences of angular errors between segments, approach and properties were recorded. Long paths correlated with smaller angular errors. CT-guided stereotaxy can be considered safe and provided precise multiple needle placement for SRFA of liver lesions at arbitrary trajectories in various segments and locations.

脳内出血に対する軟性鏡手術と硬性鏡手術の比較

While a rigid-type endoscope has been used for the surgery of intracerebral hemorrhage, a flexible fiberscopie is more maneuverable. But flexible fiberscopic surgery for intracerebral hemorrhage is challenging in terms of visual resolution of the operative field. We compared the results of this new method with that of our conventional method using a rigid-type endoscope. A flexible fiberscope with an outer diameter of 4.8-mm was inserted into hematoma cavity by free hands, or in some cases under CT-guided stereotaxy. An irrigation-suction system is used to facilitate aspiration of hematoma with hard clots. The problem of interference of the visual field with clots was solved by water irrigation of the endoscopic lens. The operation time was comparable to that of our past surgery using a rigid endoscope (58 min vs. 53 min), and the mean removal rate of hematoma was also similar to that of the rigid endoscopic surgery (77% vs. 86%). Although the results of the flexible fiberscopic surgery were comparable to that of the rigid endoscopic surgery, effective hemostat instruments are unavailable. For this reason, we select this surgery only for patients in subacute stage in which hemostat process is completed. This method is only in the developmental stage, and advances in instruments are necessary to establish it.

Developments in perforator imaging for the anterolateral thigh flap: CT angiography and CT‐guided stereotaxy

The anterolateral thigh flap is an increasingly popular reconstructive option despite uncertainty in its perforator anatomy. Perforators are not always present, vary in size and intramuscular course, and have variable cutaneous courses and supply. As such, preoperative imaging has become favored. The current study describes the preliminary use of two new modalities for preoperative imaging: computed tomography (CT) Angiography and CT-guided stereotaxy. These have been utilized in the preoperative imaging of two patients undergoing ALT flap reconstruction. Each patient underwent each of these techniques combined with Doppler ultrasound, the previous standard modality. The size, location, and course of perforators were explored and compared with operative findings. Both techniques are technically feasible, highly accurate, and provide more information to the surgeon than ultrasound. CT Angiography and CT-guided stereotaxy are useful adjuncts to Doppler ultrasound for imaging perforators prior to ALT flaps. A larger study is suggested to quantify the accuracy of these techniques.

Stereotactic image‐guided navigation in the preoperative imaging of perforators for DIEP flap breast reconstruction

Preoperative imaging is sought prior to DIEA (Deep Inferior Epigastric Artery) perforator flaps due to the potential for maximizing operative success and minimizing operative complications. Recent advances include the use of computed tomography (CT) angiography (CTA) and magnetic resonance angiography. Image-guided stereotactic surgery is a recent technique that has been used with success in several fields of surgery. The variability of perforator anatomy makes DIEA perforator flap surgery a suitable candidate for such technology, but as yet this has not been described. A study was undertaken to determine the feasibility of CT-guided stereotaxy technique in DIEA perforator flap surgery and to compare findings with both conventional CTA and operative findings. Five consecutive patients planned for an elective DIEA perforator flap were recruited. Each patient underwent preoperative imaging of the anterior abdominal wall vasculature with both conventional CTA and CT-guided stereotactic imaging. Imaging findings were compared to operative findings. In all cases, all the major perforators were accurately localized with stereotactic imaging and with conventional CTA. Stereotactic navigation demonstrated a slightly better (nonsignificant) correlation with perforator location than conventional CTA. As such, CT-guided stereotactic imaging is an accurate method for the preoperative planning of DIEA perforator flaps, providing additional and potentially more accurate data to conventional CTA. With no additional scanning required, the method described in this paper allows the combined use of both methods for preoperative planning.

The use of virtual fluoroscopy in managing acute type II odontoid fracture with anterior single-screw fixation. A safe, effective, elegant and fast form of treatment

The management of odontoid fractures represents both a clinical and a technical challenge due to the singular anatomy and biomechanics of the region. At present there is still much controversy as far as any form of management (surgical vs. conservative) is concerned and in any case there is not sufficient evidence to support a standardized form of treatment. This study was designed to further evaluate safety and efficacy of anterior odontoid single-screw fixation and to better determine the usefulness of Image Guided Surgery Virtual Fluoroscopy in treating such cases assessing also its advantages over traditional fluoroscopy and CT-guided frameless stereotaxy in the upper cervical spine surgery. This was a retrospective review of ten patients presented during a short period of 18 months with acute traumatic Type II odontoid fractures. Nine underwent fixation within a mean of 3 days after injury, whereas a patient had to be operated upon on the 22nd day due to poor alignment with conservative treatment and ongoing instability. All patients postoperatively were fitted in a collar and then followed-up with serial clinical and radiographic examinations. Radiological signs of fusion were seen in 10 cases (100%) (mean follow-up: 16 months). No complications occurred during the surgical procedure, nor were any instrumentation failures recorded; all patients remained neurologically intact. We believe that anterior odontoid screw fixation using Image Guided Surgery virtual fluoroscopy is a safe, effective, less time consuming and low x-ray exposure technique and we recommend this as the preferred treatment method for acute Type II odontoid fractures. Moreover, the use of image guided technology affords more precision, confidence and safety enabling the surgeon to approach the upper cervical spine in an easier and faster way.

CT-guided stereotaxy: first 10-year experience.

The authors present an overview on CT-guided stereotaxy performed in the last 10 years in the University Hospital Olomouc. During this period a total of 811 stereotactic brain operations were performed. Of these, 710 were done in the field of afunctional and 101 in the field of functional stereotaxy. The majority of procedures were biopsies of intracranial lesions (n = 464), evacuations of intracerebral hematomas with or without drainage and fibrinolysis (n = 147) and thalamotomies in patients with Parkinson's disease (n = 88). With the exception of the two years at the beginning, the number of yearly performed stereotaxies varied between 66-106 (mean, 86.9). Serious complications appeared after three procedures (0.37 %).

Ultrasound-guided aspiration of brain abscesses through a single burr hole.

Surgical aspiration and/or drainage of brain abscesses is considered to be the first-line treatment for abscesses larger than 25 mm. This is ususally performed with the aid of CT-guided stereotaxy. A method of ultrasound guidance is presented that allows a single burr hole approach with real-time imaging of the whole procedure. A bayonet-like shaped ultrasound probe with tip dimension of 8 x 8 mm only (EUP-NS 32, Hitachi/Ecoscan) with frequencies of 3.5 and 5 MHz is used. After placement of a burr hole the target is identified by transdural insonation, a guideline is adjusted and a mounted puncture-adapter guides the cannula towards the lesion under real-time imaging control. Up to now 12 abscesses in 10 patients were treated. Visualization was always excellent. A second aspiration had to be performed twice. One abscess did not contain enough pus to be cured by aspiration and was removed by open surgery, another could not be tapped by the blunt cannula and was aspirated under stereotactic control using a sharp trocar. Outcome was excellent in 6 patients and fair in 2 patients but this was due to the pre-existing disease. Two patients admitted in deep coma died despite an emergency operation. The presented method has proven to be a very powerful guiding tool in the surgical treatment of brain abscesses through a single burr hole approach.

Accuracy of true frameless stereotaxy: in vivo measurement and laboratory phantom studies

The authors present the results of accuracy measurements, obtained in both laboratory phantom studies and an in vivo assessment, for a technique of frameless stereotaxy. An instrument holder was developed to facilitate stereotactic guidance and enable introduction of frameless methods to traditional frame-based procedures. The accuracy of frameless stereotaxy was assessed for images acquired using 0.5-tesla or 1.5-tesla magnetic resonance (MR) imaging or 2-mm axial, 3-mm axial, or 3-mm helical computerized tomography (CT) scanning. A clinical series is reported in which biopsy samples were obtained using a frameless stereotactic procedure, and the accuracy of these procedures was assessed using postoperative MR images and image fusion. The overall mean error of phantom frameless stereotaxy was found to be 1.3 mm (standard deviation [SD] 0.6 mm). The mean error for CT-directed frameless stereotaxy was 1.1 mm (SD 0.5 mm) and that for MR image-directed procedures was 1.4 mm (SD 0.7 mm). The CT-guided frameless stereotaxy was significantly more accurate than MR image-directed stereotaxy (p = 0.0001). In addition, 2-mm axial CT-guided stereotaxy was significantly more accurate than 3-mm axial CT-guided stereotaxy (p = 0.025). In the clinical series of 21 frameless stereotactically obtained biopsies, all specimens yielded the appropriate diagnosis and no complications ensued. Early postoperative MR images were obtained in 16 of these cases and displacement of the biopsy site from the intraoperative target was determined by fusion of pre- and postoperative image data sets. The mean in vivo linear error of frameless stereotactic biopsy sampling was 2.3 mm (SD 1.9 mm). The mean in vivo Euclidean error was 4.8 mm (SD 2 mm). The implications of these accuracy measurements and of error in stereotaxy are discussed.

A CT-guided stereotactic system with direct verification of the centrage of the target before introducing the needle into the brain

The author reports his experience with a stereotactic apparatus which gives more protection to patients during stereotactic operations. This apparatus allows the verification of the centrage of the target before puncturing the brain with the needle. In the most common stereotactic systems there is a headframe with three or four pins for the fixation to the skull. This apparatus is more simple: there is no frame and there is only one point of fixation to the skull: a small, L-shaped, aluminum bar, fixed in the right prefrontal region with two small screws. Because this system has only one point of fixation to the skull, it is movable like a bell. Besides the possibility of a direct verification of thé centrage of the target, that has induced the author to study a new stereotactic apparatus for CT-guided stereotaxy, the small size of the apparatus means that it does not interfere with surgery in microneurosurgical stereotactic directed operations. This stereotactic apparatus can be used with CT-scan because it is aluminium with some parts in brass. The system, moreover, can be used whether scanner-dependent or scanner-independent, using two different softwares for calculation of the centrage of the target. [Neurol Res 1999; 21: 111-116]

A low cost modification of an old Leksell stereotactic frame to allow CT-guided stereotaxy

The high cost of commercial CT-compatible stereotactic frames has restricted the availability of CT-guided stereotaxy for many neurosurgical centres. However, many of these centres do possess the standard stereotactic frames for projection radiography, of which the old type Leksell frame is probably the most common. We have devised a simple and low-cost modification to an old Leksell frame to allow CT-guided stereotaxy. The nature of the modifications allow complete freedom of positioning of the frame relative to the CT scanner and coordinate transformations can be performed simply and effectively. The modified frame has been used successfully for some 18 months and the modification has now been performed at two centres in the North West Regional Health Authority. We hope this modification will allow many other centres to embark on CT-guided stereotaxy.

Avoiding empiric therapy for brain masses in Indian patients using CT-guided stereotaxy

Empiric therapy, especially antituberculous therapy, is frequently given to Indian patients with brain masses. This report documents our experience in avoiding such therapy using CT-guided stereotaxy. Out of 101 procedures done on 99 patients with brain masses, 80 were done to obtain a histological diagnosis and 21 for therapeutic purposes. There was no mortality and 2% morbidity. A positive diagnosis was obtained in 94% (75/80) of patients undergoing a biopsy. Diagnosis of tuberculous lesions was based mainly on the presence of acid-fast bacilli in the biopsy specimen or pus. In six patients the radiological diagnosis was wrong and in one the diagnosis was not certain. Inappropriate therapy was given to three patients, on the basis of a CT or MRI scan, before a biopsy was done. It is essential that a histological diagnosis be obtained in all patients with brain masses and there is no role for empirical therapy except in isolated cases.

Treatment of cystic astrocytomas with intracavitary phosphorus 32.

Cyst formation by astrocytomas can cause progressive neurological deficit and can necessitate multiple surgical procedures. Before the advent of computed tomography (CT) preoperative diagnosis of cystic astrocytomas was difficult and stereotactic management of these lesions was limited. CT-guided stereotaxy provides a safe approach to all cystic astrocytomas including brain stem lesions. Based upon the experience of intracavitary radiation of craniopharyngioma cysts, the authors treated nine patients presenting with cystic astrocytomas utilizing colloidal chromium phosphorus 32 (32P). Control of cyst formation was achieved in eight patients. Our preliminary data suggest that intracavitary 32P may provide a significant adjunctive therapy in the management of cystic astrocytomas.

A simple and inexpensive method for CT-guided stereotaxy.

A simple and inexpensive method for CT-guided stereotaxy is described. The method requires neither sophisticated computer programs nor additional stereotactic equipment, such as special head holders for the CT, and can be easily obtained without technical assistance. The method is designed to yield the vertical coordinates.