• Journal of Korean Neurosurgical Society
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• v.63 no.2
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• pp.210-217
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• 2020

Objective : To analyze the accuracy of iliac screws using freehand technique performed by the same surgeon. We also analyzed how the breach of iliac screws was related to the clinical symptoms resulting in revision surgery. Methods : From January 2009 to November 2015, 100 patients (193 iliac screws) were analyzed using postoperative computed tomography scans. The breaches were classified based on the superior, inferior, lateral, and medial iliac wall violation by the screw. According to the length of screw extrusion, the classification grades were as follows : grade 1, screw extrusion <1 cm; grade II, 1 cm ≤ screw extrusion <2 cm; grade III, 2 cm ≤ screw extrusion <3 cm; and grade IV, 3 cm ≤ screw extrusion. We also reviewed the revision surgery associated with iliac screw misplacement. Results : Of the 193 inserted screws, 169 were correctly located and 24 were misplaced screws. There were eight grade I, six grade II, six grade III, and four grade IV screw breaches, and 11, 8, 2, and 3 screws violated the medial, lateral, superior, and inferior walls, respectively. Four revision surgeries were performed for the grade III or IV iliac screw breaches in the lateral or inferior direction with respect to its related symptoms. Conclusion : In iliac screw placement, 12.4% breaches developed. Although most breaches were not problematic, symptomatic violations (2.1%) could result in revision surgery. Notably, the surgeon should keep in mind that lateral or inferior wall breaches longer than 2 cm can be risky and should be avoided.

• Journal of Korean Neurosurgical Society
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• v.60 no.5
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• pp.604-609
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• 2017

Objective : An adjustable Ghajar guide is presented to improve the accuracy of the original Ghajar guide technique. The accuracy of the adjustable Ghajar guide technique is also investigated. Methods : The coronal adjustment angle from the orthogonal catheter trajectory at Kocher's point is determined based on coronal head images using an electronic picture archiving and communication system. For the adjustable Ghajar guide, a protractor is mounted on a C-shaped basal plate that is placed in contact with the margin of a burrhole, keeping the central $0^{\circ}$ line of the protractor orthogonal to the calvarial surface. A catheter guide, which is moved along the protractor and fixed at the pre-determined adjustment angle, is then used to guide the ventricular catheter into the frontal horn adjacent to the foramen of Monro. The adjustable Ghajar guide technique was applied to 20 patients, while a freehand technique based on the surface anatomy of the head was applied to another 47 patients. The accuracy of the ventricular catheter placement was then evaluated using postoperative computed tomography scans. Results : For the adjustable Ghajar guide technique (AGT) patients, the bicaudate index ranged from 0.23 to 0.33 ($mean{\pm}standard$ deviation [SD] : $0.27{\pm}0.03$) and the adjustment angle ranged from $0^{\circ}$ to $10^{\circ}$ ($mean{\pm}SD:5.2^{\circ}{\pm}3.2^{\circ}$). All the AGT patients experienced successful cerebrospinal fluid diversion with only one pass of the catheter. Optimal placement of the ventricular catheter in the ipsilateral frontal horn approximating the foramen of Monro (grade 1) was achieved in 19 patients (95.0%), while a suboptimal trajectory into a lateral corner of the frontal horn passing along a lateral wall of the frontal horn (grade 3) occurred in 1 patient (5.0%). Thus, the AGT patients experienced a significantly higher incidence of optimal catheter placement than the freehand catheterized patients (95.0% vs. 68.3%, p=0.024). Moreover, none of the AGT patients experienced any tract hemorrhages along the catheter or procedure-related complications. Conclusion : The proposed adjustable Ghajar guide technique, using angular adjustment in the coronal plane from the orthogonal trajectory at Kocher's point, facilitates accurate freehand placement of a ventricular catheter for hydrocephalic patients.

• Journal of Korean Neurosurgical Society
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• v.50 no.4
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• pp.317-321
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• 2011

Objective : External ventricular drain (EVD) is commonly performed with a freehand technique using surface anatomical landmarks at two different cranial sites, Kocher's point and the forehead. The aim of this study was to evaluate and compare the accuracy and safety of these percutaneous ventriculostomies. Methods : A retrospectively review of medical records and head computed tomography scans were examined in 227 patients who underwent 250 freehand pass ventriculostomy catheter placements using two different methods at two institutions, between 2003 and 2009. Eighty-one patients underwent 101 ventriculostomies using Kocher's point (group 1), whereas 146 patients underwent 149 forehead ventriculostomies (group 2). Results : In group 1, the catheter tip was optimally placed in either the ipsilateral frontal horn or the third ventricle, through the foramen of Monro (grade 1) in 82 (81.1%) procedures, in the contralateral lateral ventricle (grade 2) in 4 (3.9%), and into eloquent structures or non-target cerebrospinal space (grade 3) in 15 (14.8%). Intracerebral hemorrhage (ICH) >1 mL developed in 5 (5.0%) procedures. Significantly higher incidences of optimal catheter placements were observed in group 2. ICH>1 mL developed in 11 (7.4 %) procedures in group 2, showing no significant difference between groups. In addition, the mean interval from the EVD to ventriculoperitoneal shunt was shorter in group 2 than in group 1, and the incidence of EVD-related infection was decreased in group 2. Conclusion : Accurate and safe ventriculostomies were achieved using both cranial sites, Kocher's point and the forehead. However, the forehead ventriculostomies provided more accurate ventricular punctures.

• Journal of Veterinary Clinics
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• v.39 no.6
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• pp.294-301
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• 2022

Three-dimensional (3D) printing technique has been widely used for accurate screw and pin placement in orthopedic surgery and neurosurgery. However, there are few reports comparing the accuracy between the patient-specific guides and freehand Kirschner wire (K-wire) placement in toy, small and medium breed dogs. This study aimed to assess the accuracy of 3D printed patient-specific guides (PSGs) in pin insertion in the thoracolumbar vertebrae of toy breed dogs and compare the outcomes between novice and experienced surgeons. The experiment was conducted on the thoracolumbar vertebrae of 21 euthanized toy breed dogs (median weight, 5.95 kg). The optimal insertion angle placement was determined and patient-specific guides for K-wire insertion were designed and 3D printed using computed tomography (CT) and a 3D computer-aided design program of three vertebrae (Thoracic 12-Lumbar 1). K-wire tracts were made by experienced and novice surgeons and compared to assess the accuracy based on postoperative CT. Based on postoperative CT, in the experienced group, 61 out of 63 pins (96.8%) were fully contained inside the vertebral body and lamina, whereas two pins (3.2%) had perforated the vertebral canal (grade 3, 2-4 mm breach). However, all the pins in the novice group were fully contained. The use of 3D printed PSGs for pin insertion in the thoracolumbar region is an accurate and safe alternative to freehand screw placement by novice surgeons in toy, small and medium breed dogs. Operations with 3D printed PSGs allow novice surgeons to achieve better or similar outcomes in accurate placement of pin/screws in vertebrae.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6066-6071
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• 2013

This paper proposes a calibration method for a freehand 3-D ultrasound system in medical robotic research. The calibration block with six wires was designed to set the fixed target points. The positions of the ultrasound probe and calibration block were measured using an optical tracker. The relationship between the position of the ultrasound probe and the pixel coordinates in the images was derived using a calibration process. The scaling matrix was also calculated. The experimental results showed that the proposed method could find solutions using a simple least square method from one or multiple ultrasound images.

• Journal of Korean Neurosurgical Society
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• v.63 no.6
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• pp.777-783
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• 2020

Objective : To compare the accuracy and breach rates of freehand (FH) versus navigated (NV) pedicle screws in the thoracic and lumbar spine in patients with metastatic spinal tumors. Methods : A retrospective review of adult patients who underwent pedicle screw fixation in the thoracic or lumbar spine for metastatic spinal tumors between 2012 and 2018 was conducted. Breaches were assessed based on the Gertzbein and Robbins classification and only screws placed >4 mm outside of the pedicle wall (lateral or medial) were considered breached. Results : A total of 62 patients received 547 pedicle screws (average 8 per patient) - 34 patients received 298 pedicle screws in the FH group and 28 patients received 249 screws in the NV group. There were 40/547 breaches, corresponding to a breach and accuracy rate of 7.3% and 92.7%, respectively. The breach rate was 9.7% in the FH group and 4.4% in the NV group (chi-squared test, p=0.017); this corresponded to an accuracy rate of 90.3% and 95.6%, respectively. Only one patient from the overall cohort (in the FH group) required revision surgery due to a medial breach abutting the spinal cord (1.6% of all patients; 2.9% of FH patients); no patient suffered organ, vessel, or neurological injury from screw breaches. Conclusion : Navigated pedicle screw placement in patients with metastatic spinal tumors has a significantly higher radiographic accuracy compared to the FH technique. However, the revision surgery was low and no patient suffered from clinically-relevant breach. Navigation also offers the advantage of real-time localization of spinal tumors and aids in targeting and resection of these lesions.

• Journal of Korean Neurosurgical Society
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• v.61 no.1
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• pp.75-80
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• 2018

Objective : Among the various sacropelvic fixation methods, S2 alar-iliac (S2AI) screw fixation has several advantages compared to conventional iliac wing screw. However, the placement of S2AI screw still remains a challenge. The purpose of this study was to describe a novel technique of free hand S2AI screw insertion using a K-wire and cannulated screw, and to evaluate the accuracy of the technique. Methods : S2AI screw was inserted by free hand technique in sixteen consecutive patients without any fluoroscopic guidance. The gearshift was advanced to make a pilot hole passing through the sacroiliac joint and directing the anterior inferior iliac spine. A K-wire was placed through the pilot hole. After introducing a cannulated tapper along with the K-wire, a cannulated S2AI screw was installed over the K-wire. Results : Thirty-three S2AI screws were placed in sixteen consecutive patients. Thirty-two screws were cannulated screws, and one screw was a conventional non-cannulated screw. Thirty out of 32 (93.8%) cannulated screws were accurately positioned, whereas two cannulated screws and one non-cannulated screw violated lateral cortex of the ilium. Conclusion : The technique using K-wire and cannulated screw can provide accurate placement of free hand S2AI screw.

• Journal of Korean Neurosurgical Society
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• v.64 no.2
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• pp.247-254
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• 2021

Objective : The subaxial cervical pedicle screwing technique shows powerful biomechanical properties for posterior cervical fusion. When applying a pedicle screw using the freehand technique, it is essential to analyse cervical computed tomography and plan the surgery accordingly. Normal cervical computed tomography is usually performed in the supine position, whereas during surgery, the patient lies in a prone position. This fact leads us to suppose that radiological evaluations may yield misleading results. Our study aimed to investigate whether there is any superiority between preoperative preparation on computed tomography performed in the prone position and that performed in the supine position. Methods : This study included 17 patients (132 pedicle screws) who were recently operated on with cervical vertebral computed tomography in the prone position and 17 patients (136 pedicle screws) who were operated on by conventional cervical vertebral computed tomography as the control group. The patients in both groups were compared in terms of age, gender, pathological diagnosis, screw malposition and complications. A screw malposition evaluation was made according to the Gertzbein-Robbins scale. Results : No statistically significant difference was observed between the two groups regarding age, gender and pathological diagnosis. The screw malposition rate (from 11.1% to 6.9%, p<0.05), mean malposition distance (from 2.18 mm to 1.86 mm, p <0.05), and complications statistically significantly decreased in the prone position computed tomography group. Conclusion : Preoperative surgical planning by performing cervical vertebral computed tomography in the prone position reduces screw malposition and complications. Our surgical success increased with a simple modification that can be applied by all clinicians without creating additional radiation exposure or additional costs.

• Journal of Biomedical Engineering Research
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• v.44 no.4
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• pp.255-263
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• 2023

Clinical ultrasound (US) is a widely used imaging modality with various clinical applications. However, capturing a large field of view often requires specialized transducers which have limitations for specific clinical scenarios. Panoramic imaging offers an alternative approach by sequentially aligning image sections acquired from freehand sweeps using a standard transducer. To reconstruct a 3D volume from these 2D sections, an external device can be employed to track the transducer's motion accurately. However, the presence of optical or electrical interferences in a clinical setting often leads to incorrect measurements from such sensors. In this paper, we propose a deep learning (DL) framework that enables the prediction of scan trajectories using only US data, eliminating the need for an external tracking device. Our approach incorporates diverse data types, including correlation volume, optical flow, B-mode images, and rawer data (IQ data). We develop a DL network capable of effectively handling these data types and introduce an attention technique to emphasize crucial local areas for precise trajectory prediction. Through extensive experimentation, we demonstrate the superiority of our proposed method over other DL-based approaches in terms of long trajectory prediction performance. Our findings highlight the potential of employing DL techniques for trajectory estimation in clinical ultrasound, offering a promising alternative for panoramic imaging.