Virtual Navigation System Research Articles

Interactive Digital Campus Visual Navigation System Design and Development

Designing an interactive virtual navigation system needs consideration of compositive features such as modelling, movement control and object selection. Those features are key to meet end user requirements. Current virtual navigation systems are not beneficial to popularize in the case of development environment, methods and technologies. That is because such systems have limited application area and costs. Proprietary development environment result in limited selection in system components while new development technologies are unlikely to be accepted as staggering capital costs. In this paper, we propose a feasible scheme and development environment to design an interactive virtual navigation system for creating and utilizing digital campus models. Furthermore, the scheme also captures user interactivities via mouse and keyboard for further controls and selections in virtual campus. By adequate consideration of user preferences and personalities, this system benefits in portability, flexibility; has a high degree of standardization and lower cost.

Diagnostic yield of combined bronchoscopy and endobronchial ultrasonography, under LungPoint guidance for small peripheral pulmonary lesions

The yield of biopsy performed during bronchoscopy is reduced if the lesion is smaller than 30 mm. We evaluated the performance of a new diagnostic technique combining endobronchial ultrasonography with a guide sheath (EBUS-GS) and a virtual bronchoscopic navigation system, LungPoint (Broncus Technologies, Inc., Mountain View, CA, USA), for the diagnosis of small (≤30 mm) peripheral pulmonary lesions (PPL). Between May 2011 and December 2011, we recruited 68 consecutive patients presenting with a PPL 30 mm or less in diameter determined by chest computed tomography. We used the LungPoint system before bronchoscopy to identify the bronchus into which the bronchoscope should be advanced. We used a thin bronchoscope. EBUS-GS was performed using an endoscope ultrasonography system equipped with a 20-MHz mechanical radial-type probe. We used a guide sheath with an external diameter of 1.95 mm, thin forceps and brushing. The diagnostic yield of the 68 PPL was 77.9%; it was 83.7% and 68.0% for the malignant and benign lesions, respectively. Notably, three cases were diagnosed by transbronchial needle-aspiration cytology alone. Univariate and multivariate analyses showed that the EBUS probe localization was the most significant contributor to successful diagnosis (diagnostic yield: within vs adjacent to the lesion = 92.1% vs 60.0%, respectively; P = 0.004 and P = 0.003, respectively). The combination of EBUS-GS and LungPoint was useful for diagnosing small PPL.

Natural orifice translumenal endoscopic surgery: Current status and future technical development

The technology behind NOTES, an evolutionary endoscopic surgery conducted through the natural orifices of the patient to completely eliminate external post-operative scars, has been substantially improved in the last decade. The scarless nature of NOTES is believed to decrease the chance of wound infections and incision hernias, improve recovery times and increase the cosmetic satisfaction of patients. Although various animal and human studies have extended our understanding of physiology and the requirements of NOTES procedures, current NOTES technology is still too rudimentary to be applied to various clinical settings due to the technical and instrumental limitations. Recently, numerous efforts have been made in the development of proper surgical instruments for NOTES procedures. A secure closure method for luminal perforation is one of the most actively investigated areas, and several promising devices have already been introduced. A virtual navigation system for flexible endoscopic instruments would be beneficial for surgical reliability and safety issues by assisting the narrow endoscopic visual field. Various retraction devices are also necessary to enable complex endoscopic surgical maneuvers. Unfortunately, engineers have only taken supportive roles in the history of NOTES development, though engineering experience and knowledge are crucial for the development of complicated and miniaturized endoscopic devices. The active involvement of engineers in NOTES technology is required for the realization of NOTES in routine clinical practice.

Fluoroscopy-assisted thoracoscopic resection after computed tomography-guided bronchoscopic metallic coil marking for small peripheral pulmonary lesions

To re-evaluate the efficacy of fluoroscopy-assisted thoracoscopic resection after computed tomography (CT)-guided bronchoscopic metallic coil marking (FATS-CM), which was our original method for small peripheral pulmonary lesions. Fifty-eight patients with 63 lesions underwent FATS-CM. A metallic coil was installed in the bronchus nearest to the lesion under CT fluoroscopic guidance with ultrathin bronchoscopy. The virtual bronchoscopic navigation (VBN) system was used in 14 cases. Afterwards, we basically performed wide wedge resection (WWR) using a C-arm-shaped roentgenographic fluoroscope during thoracoscopic surgery initially, and then the final procedure was determined by intraoperative histological diagnosis. Moreover, we prospectively treated ground-glass opacity (GGO) lesions of <20 mm diameter according to our treatment protocol from September 2004. We could install coils in the objective bronchi in all cases. The average time required for the marking procedure was 38.9 (15-120) min. Pneumothorax was recognized in 1 (1.7%) case as a complication, but no fatal complications occurred. We could also install coils for each lesion in 4 cases (9 lesions) with multiple lesions. In 14 cases with the VBN system, the examination time and CT number were significantly reduced (P < 0.05 and <0.001, respectively), compared with those of 40 cases without the VBN system. The average interval between the CM and the operation was 5.6 (0-30) days. We never experienced a case of migration preoperatively. Sixty-two (98.4%) lesions were definitively identified, and WWRs were performed using three trocars in 58 (92.1%) cases during thoracoscopic surgery. Lobectomy was initially performed in only 1 case owing to coil migration. Thirty-seven of 40 cases (92.5%) were in line with the treatment protocol. There were no local-regional recurrences in all cases undergoing WWR. We could prospectively show that our method was suitable to perform WWR with a sufficient margin for small GGO lesions of <20 mm. Moreover, we reconfirmed that the advantages of our method were safety, permitting flexibility in scheduling operations and a high ability to deal with multiple lesions. Additionally, our method became a minimally invasive and mature technique by using a new VBN system.

The Interface Design and Usability Evaluation of Interactive Virtual Reality Navigation System

Virtual reality is an innovative technology, which allows users to immerse in an imagined situation. Therefore, promoting virtual reality technology can provide more natural and specific interaction mode. The purpose of this study is to investigate interactive virtual reality navigation system by testing 15 participants to evaluate the system and analyze the results with Delphi method and Heuristic Evaluation. Besides, we used Questionnaire for User Interaction Satisfaction (QUIS), Usability Metric for User Experience (UMUX) questionnaires and interviews to understand user experience. The results show the new system is better than the old one. The interactive VR navigation system design principles (easy to use, consistency, richness, feedback, simple prompt and documentation) obtained from this study can be used to enhance the satisfaction of the users when designing the interactive VR navigation system in the future.

Accuracy of lower cervical pedicle screw placement with assistance of distinct navigation systems: a human cadaveric study

Evaluate the accuracy of five different techniques for lower cervical pedicle screw placement. Forty human cadaveric cervical spines were equally divided into five groups, and each group had eight specimens. Pedicle screws with dia. 3.5 mm were used. Group 1 was blind screw placement without any assistance; Group 2-5 was assisted by the X-ray fluoroscopy, virtual fluoroscopy navigation system, CT-based navigation system, and Iso-C 3D navigation system, respectively. Thereafter, cortical integrity of each pedicle was evaluated by anatomic dissection of the specimens. A total of 398 pedicle screws were inserted. In the Group 1-5, the average operation time per sample was 27 ± 3.0, 112 ± 10.3, 69 ± 6.4, 98 ± 11.0, and 91 ± 6.0 min, respectively. The outcome for excellent, fair and poor were 29 (36.3 %), 21 (26.2 %) and 30 (37.5 %) in Group 1; 35 (44.9 %), 29 (37.2 %) and 14 (17.9 %) in Group 2; 34 (42.5 %), 36 (45.0 %) and 10 (12.5 %) in Group 3; 70 (87.5 %), 10 (12.5 %) and 0 (0.0 %) in Group 4; 72 (90.0 %), 8 (10.0 %) and 0 (0.0 %) in Group 5. Blind screw placement was surely unsafe. Lower cervical pedicle screw placement assisted by the CT-based navigation system or the Iso-C 3D navigation system significantly improved the accuracy compared to the fluoroscopy assistance and the virtual fluoroscopy navigation assistance.

Advances in the clinical application of virtual liver surgery

Three-dimensional modeling of the liver using CT scan or MRI data improves surgical planning.Threedimensional simulation of hepatectomy facilitates intraoperative identification of the vascular anatomy and control of the hepatic blood flew,and accurately predicts the volume of liver to be resected and surgical margins.Preoperative virtual hepatectomy might be useful not only to facilitate laparoscopic hepatectomy but also to improve therapeutic efficacy. A virtual navigation system enables users to revert to previously recorded digital imaging data at any time during radiofrequency ablation procedures.The spatial information gained from three-dimensional imaging facilitates an appropriate needle path to the target and projects the intended ablation area in three dimenisions.The safety and efficacy of radiofrequency ablation assisted by this navigation system may substantially improve as it is used in clinical practice. Augmented reality superimposes the preoperative threedimensional liver model onto the real intraoperative view of the patient.Augmented reality provides surgeons with a transparent view of the liver and guides surgeons by providing virtual augmentation of their real surgical tools.These virtally augmented tools are tracked in real-time during the procedure,thereby optimizing therapy. Key words: Liver diseases ; Digital medicine ; Laparoscopy ; Radiofrequency ablation ; Navigation ; Augmented reality ;

Biopsy guided by real-time virtual navigation system using computed tomography imaging data:a phantom study

Objective To verify the feasibility and the accuracy for the biopsy of targets not visible on sonography but shown on CT in a phantom by using real-time virtual navigation system(RVS).Methods The tissue mimicking phantom,made of gel,contained 30 red spheres which were 10 mm in diameter,randomly placed.These spheres were invisible on sonography,but visible on CT.A junior operator and a senior operator performed the biopsy respectively,and each sphere was biopsied once guide by both RVS and conventional ultrasound for each operator.The red dye in the biopsied sample meant successful performance.The success rate of biopsy and the length of the red dyed sample were recorded.Results There was no statistically difference between the performance results of the two operators.The success rate and the median length of red dyed sample biopsy of RVS were respectively 96.7％ (58/60) and 7.5 mm (rang,6-9 mm) which were statistically higher and longer than that of conventional ultrasound,43.3％(26/60) and 0 mm(rang,0 - 5 mm) ( P ＜0.05).Conclusions Biopsy guided by RVS for the target invisible to ultrasound is a feasible and accuracy method,which will be a new guided method for interventional ultrasound. Key words: Ultrasonography ; Phantoms, imaging; Biopsy, needle; Real-time virtual navigation system

Percutaneous radiofrequency ablation of virtual tumours in canine kidney using Global Positioning System‐like technology

What's known on the subject? And what does the study add? We have previously shown that percutaneous radiofrequency ablation guided by image-fusion technology allows for precise needle placement with real time ultrasound superimposed with pre-loaded imaging, removing the need for real-time CT or MR guidance. Emerging technology also allows real-time tracking of a treatment needle within an organ in a virtually created 3D format. To our knowledge, this is the first study utilising a sophisticated ultrasound-based navigation system that uses both image-fusion and real-time probe-tracking technologies for in-vivo renal ablative intervention. • To evaluate the feasibility, accuracy and efficacy of ultrasonography (US)-guided percutaneous radiofrequency ablation (RFA) in the canine kidney model using novel Global Positioning System-like probe tracking technology. • Virtual tumours in the canine kidney were ablated in vivo by percutaneous RFA guided exclusively by two-dimensional (2D) US and a virtual navigation system. • Gold fiducial markers were inserted into renal parenchyma to serve as centres of virtual tumours. • After capturing 2D US images, navigation software created a three-dimensional planning model of the kidney, and superimposed it onto the live US image. • Percutaneous RFA was guided by multiplanar navigation, showing real-time probe positions within the superimposed images, to treat each virtual tumour with a single treatment. • Navigator software predicted the percentage of tumour treated; treated kidney specimens were examined to evaluate projection and targeting accuracy. • In total, 32 virtual tumours (median diameter 16 mm, range 10-24 mm) were treated in 16 canine kidneys. • Median (range) error between 'fiducial tumour centre' and 'treated area centre' was 1.8 (0-25) mm. • Targeting accuracy improved with experience: median (range) error decreased from 6.3 (2-25) mm in an initial 12 tumours to 1.3 (0-9.0) mm in the last 20 tumours (P= 0.008). • The percentage (range) of tumour actually treated improved significantly from the initial series at 23% (0-100%) to 100% (51-100%) (P < 0.001). • Overall, navigator-reported and pathologically confirmed treatment percentages were correlated significantly (r= 0.5; P= 0.006). • Percutaneous renal RFA guided exclusively by real-time 2D US with multiplanar Global Positioning System-like probe tracking is feasible and accurate. • Near-future technologies, including elastic fusion overlay and anticipation of soft-tissue deformation, will further augment this guidance system.

Evaluation of a Navigation System for Dental Implantation as a Tool to Train Novice Dental Practitioners

This study evaluated the benefits of a virtual reality navigation system for teaching the surgical stage of dental implantation to final-year dental students. The study aimed to assess the students' performance in dental implantation assignments by comparing freehand protocols with virtual reality navigation. Forty final-year dentistry students without previous experience in dental implantation surgery were given an implantation assignment comprising 3 tasks. Marking, drilling, and widening of implant holes were executed by a freehand protocol on the 2 mandibular sides by 1 group and by virtual reality navigation on 1 side and contralaterally with the freehand protocol by the other group. Subjective and objective assessments of the students' performance were graded. Marking with the navigation system was more accurate than with the standard protocol. The 2 groups performed similarly in the 2-mm drilling on the 2 mandibular sides. Widening of the 2 mesial holes to 3 mm was significantly better with the second execution in the standard protocol group, but not in the navigation group. The navigation group's second-site freehand drilling of the molar was significantly worse than the first. The execution of all assignments was significantly faster in the freehand group than in the navigation group (60.75 vs 77.25 minutes, P = .02). Self-assessment only partly matched the objective measurements and was more realistic in the standard protocol group. Despite the improved performance with the navigation system, the added value of training in dental implantation surgery with virtual reality navigation was minimal.

Virtual navigation assisted contrast-enhanced ultrasound for focal liver lesion invisible in B-mode ultrasound

Objective To evaluate virtual navigation assisted contrast-enhanced ultrasound(VN-CEUS) by comparing VN-CEUS with routine CEUS in detecting focal liver lesion(FLL) invisible in B-mode ultrasound(BUS).Methods Forty-seven FLLs invisible in BUS were identified by CT/MR,and received VN-CEUS and routine CEUS respectively.Results The detection rate of VN-CEUS and routine CEUS were 78.7%(37/47) and 36.2%(17/47),the former was much higher than the later (P<0.01).In all the cases,fusion of CT/MR with ultrasound was achieved successfully and average time for image fusion was 5 min.compared with routine CEUS,VN-CEUS could more easily find FLLs shadowed by lung or ribs,FLLs in inhomogeneous liver background,and FLLs with brief or inapparent abnormal enhancement.ConclusionsVN-CEUS can greatly improve the detection rate of FLL that was invisible in BUS. Key words: Ultrasonography; Microbubbles; Liver diseases; Virtual navigation system

Microwave ablation assisted by a real-time virtual navigation system for hepatocellular carcinoma undetectable by conventional ultrasonography

To evaluate the efficiency and feasibility of microwave (MW) ablation assisted by a real-time virtual navigation system for hepatocellular carcinoma (HCC) undetectable by conventional ultrasonography. 18 patients with 18 HCC nodules (undetectable on conventional US but detectable by intravenous contrast-enhanced CT or MRI) were enrolled in this study. Before MW ablation, US images and MRI or CT images were synchronized using the internal markers at the best timing of the inspiration. Thereafter, MW ablation was performed under real-time virtual navigation system guidance. Therapeutic efficacy was assessed by the result of contrast-enhanced imagings after the treatment. The target HCC nodules could be detected with fusion images in all patients. The time required for image fusion was 8-30 min (mean, 13.3 ± 5.7 min). 17 nodules were successfully ablated according to the contrast enhanced imagings 1 month after ablation. The technique effectiveness rate was 94.44% (17/18). The follow-up time was 3-12 months (median, 6 months) in our study. No severe complications occurred. No local recurrence was observed in any patients. MW ablation assisted by a real-time virtual navigation system is a feasible and efficient treatment of patients with HCC undetectable by conventional ultrasonography.

Clinical Application of Virtual Bronchoscopic Navigation System for Peripheral Lung Lesions

Transbronchial lung biopsy is an indispensable method for the diagnosis of peripheral lung lesions; however, the diagnostic yield still remains unsatisfactory. Endobronchial ultrasound with guide sheath (EBUS-GS) is an excellent method for the decision of biopsy points and has contributed to improvements in diagnostic yield, but the decision of choosing the proper bronchus depends on the individual ability of each bronchoscopist. To clarify the usefulness of the virtual bronchoscopic navigation system (VBN), we evaluated the diagnostic yield and time required to determine the target lesion. Fifty-seven cases using EBUS-GS with VBN (VBN/EBUS-GS group) and 55 cases using EBUS-GS (EBUS-GS group) were compared. In the VBN/EBUS-GS group, computer software detects the air density in the bronchi from the computed tomography image and imports a detailed virtual Bronchoscopic Image. After inserting the starting position and the peripheral target lesion, the software depicts the most ideal route to the target lesion during the bronchoscopic procedure. EBUS is then used to confirm the accuracy of the route. Diagnostic yield was 84.2% for the VBN/EBUS-GS group and 80.0% for EBUS-GS group. The required time to determine the biopsy position was significantly less in the VBN/EBUS-GS group (5.54 ± 0.57 min in VBN/EBUS-GS group vs. 9.27 ± 0.86 min in EBUS-GS group, P<0.01). In conclusion, VBN proved useful in shortening the time needed to determine the biopsy position.

LOVINA: Location-aware Virtual Navigation system based on active RFID

This paper presents a novel application called LOVINA for RFID computing that integrates RFID positioning technology and virtual reality. Using a museum as an example, we develop a 3D virtual navigation system that supports indoor RFID localisation. If a user is carrying a notebook or mobile device while walking through an exhibition room, the system can update the user's position accurately. This information can be used to guide users as they near particular historical objects; for example, the system can trigger special information that alerts users and helps them experience real and virtual historical relics, buildings, and incidents more completely.

Training benefits of virtual bronchoscopy prior to Endobronchial Ultrasound Guide sheath

Research questions. How does a virtual bronchoscopy navigation system (VBNS) improve prediction of candidate bronchus across a range of doctors investigating a range of lesions with Endobronchial ultrasound (EBUS) guide sheath? To what extent do benefits of virtual bronchoscopic pre-procedure navigation apply to experienced versus inexperienced bron- choscopists? Methods: Using archived EBUS Guide sheath cases, a comparison was made between identified candidate 4th order bronchus by Computerised tomography (CT) evaluation versus that identified after virtual path creation. Results: From 7 archived cases, 14 doctors identified the correct bronchus in 94 of 98 assessments (95%). Percentage of cases where there was an improvement in localisation by 2 or more 4th order bronchi was 39.8% overall (28.6% – 51.0%), 26.6 for experienced and 53.1 for inexperienced bronchoscopists (p < 0.02). The absolute mean number of 4th order bronchi different between CT and VBNS was 2.0 ± 2.6 overall, 1.2 (range 0-6) for experienced, and 2.8 (range 0-11) for inexperienced bronchoscopists. Virtual Path software calculation time was 8.1 ± 2.7 minutes, compared to 3.6 ± 2.1 minutes by CT. Conclusion: VBNS allowed rapid accurate assessment with minimal software training. Greatest benefits in reduction of procedure time were obtained in inexperienced bronchoscopists, and VBNS could allow more rapid skill development in EBUS GS in these doctors.

A Single Center Prospective Study on the Outcome of a Novel Virtual Bronchoscopic Navigation System, LungPoint, in Diagnosis of Pulmonary Lesions and/or Mediastinal/Hilar Lymphadenopathy

PURPOSE: Lung Point Virtual Bronchoscopic Navigation System (LPVBN) is a sophisticated planning and assessment module, with side-by-side visual synchronization of the real-time and virtual airway navigation to the desired target lesion. We evaluated the feasibility, diagnostic yield, and complications of the procedure for diagnosis of pulmonary lesions (including peripheral pulmonary lesions and lesions < 2cm in diameter), mediastinal, and hilar lymphadenopathy.

Magnetically Guided 3-Dimensional Virtual Neuronavigation for Neuroendoscopic Surgery

The authors have developed a novel intraoperative neuronavigation with 3-dimensional (3D) virtual images, a 3D virtual navigation system, for neuroendoscopic surgery. The present study describes this technique and clinical experience with the system. Preoperative imaging data sets were transferred to a personal computer to construct virtual endoscopic views with image segmentation software. An electromagnetic tracker was used to acquire the position and orientation of the tip of the neuroendo-scope. Virtual endoscopic images were interlinked to an electromagnetic tracking system and demonstrated on the navigation display in real time. Accuracy and efficacy of the 3D virtual navigation system were evaluated in a phantom test and on 5 consecutive patients undergoing neuroendoscopic surgery. Virtual navigation views were consistent with actual endoscopic views and trajectory in both phantom testing and clinical neuroendoscopic surgery. Anatomic structures that can affect surgical approaches were adequately predicted with the virtual navigation system. The virtual semitransparent view contributed to a clear understanding of spatial relationships between surgical targets and surrounding structures. Surgical procedures in all patients were performed while confirming with virtual navigation. In neurosurgery with a flexible neuroscope, virtual navigation also demonstrated anatomic structures in real time. The interactive method of intraoperative visualization influenced the decision-making process during surgery and provided useful assistance in identifying safe approaches for neuroendoscopic surgery. The magnetically guided navigation system enabled navigation of surgical targets in both rigid and flexible endoscopic surgeries.

Real-Time 3-Dimensional Virtual Reality Navigation System with Open MRI for Breast-Conserving Surgery

The aim of this study was to report on the early experiences using a real-time 3-dimensional (3D) virtual reality navigation system with open MRI for breast-conserving surgery. We developed a real-time 3D virtual reality navigation system with open MRI, and evaluated the mismatch between the navigation system and real distance using a 3D phantom. Two patients with nonpalpable MRI-detected breast tumors underwent breast-conserving surgery under the guidance of the navigation system. An initial MRI for the breast tumor using skin-affixed markers was performed immediately before excision. A percutaneous intramammary dye marker was applied to delineate an excision line, and the computer software "3D Slicer" generated a real-time 3D virtual reality model of the tumor and the puncture needle in the breast. Excision of the tumor was performed in the usual manner along the excision line indicated with the dye. The resected specimens were carefully examined histopathologically. The mean mismatch between the navigation system and real distance was 2.01 +/- 0.32 mm when evaluated with the 3D phantom. Under guidance by the navigation system, a percutaneous intramammary dye marker was applied without any difficulty. Fiducial registration errors were 3.00 mm for patient no. 1, and 4.07 mm for patient no. 2. Histopathological examinations of the resected specimens of the 2 patients showed noninvasive ductal carcinoma in situ. The surgical margins were free of carcinoma cells. Real-time 3D virtual reality navigation system with open MRI is feasible for safe and accurate excision of nonpalpable MRI-detected breast tumors. Long-term outcomes of this technique should be evaluated further.

Augmented reality neurosurgical planning and navigation for surgical excision of parasagittal, falcine and convexity meningiomas

Objective. To assess the utility of pre-operative 3-dimension (3D) visualisation and surgical planning with the Dextroscope™ in combination with the use of DEX-Ray—a novel augmented reality surgical navigation platform for resection of meningiomas in the falcine, convexity and parasagittal regions.Methods and Results. Magnetic resonance imaging (MRI) and magnetic resonance venogram (MRV) images of the patients were reconstructed in 3D using the Dextroscope workstation. Using a variety of available tools, we were able to view the tumour in various surgical angles and appreciate the intricate relationship of the tumour with respect to the surrounding structures and venous anatomy. Critical draining veins both superficial and deep to the tumour were well visualised. By varying the transparency of the overlying scalp and bone we were able to preoperatively determine the ideal size of our scalp flap and bone window for surgical approach. The Dextroscope enabled us to simulate surgical opening and various trajectories of approach while the DexRay virtual reality navigation system enabled the transfer of the Dextroscope 3D planning data into the operating by displaying it in real-time video-augmented mode which further enhanced the appreciation of the tumour's location in 3D space. Four patients underwent total excision of their meningioma while one patient had near total excision with a small residual remnant left behind at the medial third of the superior sagittal sinus. All 5 patients had good neurological recovery post-operatively.Conclusion. The use of the Dextroscope for pre-operative surgical planning allows for appreciation of complex anatomical relationships in 3D. This appreciation is further translated for use during surgical navigation utilizing the DEX-Ray platform that provided us with the superior advantage of allowing fast and accurate surgical resection confidently.

A Feasibility and Efficacy Study on Bronchoscopy With a Virtual Navigation System

The purpose of this study was to evaluate the diagnostic accuracy of bronchoscopy with virtual bronchoscopy (VB) navigation. Forty-two consecutive patients with ≤30-mm diameter peripheral pulmonary shadows or lesions that were difficult or impossible to identify on plain x-rays regardless of size were selected. Before bronchoscopy, multidetector computed tomography was performed, and VB images were created. Then, ultrathin bronchoscopy was carried out with VB navigation followed by conventional 4-mm diameter bronchoscopy. Thirty-seven patients were finally enrolled. There were 12 re-examination cases in which earlier conventional bronchoscopy was nondiagnostic. Diagnosis was established in 28 patients (25 malignant and 3 benign lesions), with the diagnostic yield of 75.7% (sensitivity 86.2%, specificity 62.5%, positive predictive value 89.3%, negative predictive value 55.6%, and accuracy 81.1%). The diagnostic yield for lesions of diameter ≤20 mm, 21 to 30 mm, and ≥31 mm were 76.9%, 76.5%, and 71.4%, respectively, for all patients, and 90%, 84.6%, and 83.3%, respectively, for malignant cases. The diagnostic yield in patients who underwent re-examinations was 83.3% for all cases and 88.9% for malignant cases. Three patients had completely invisible shadows on x-ray fluoroscopy and all of these cases were diagnosed on bronchoscopy. No statistically significant difference was observed between the diagnostic yield for the different sizes, pathology, and number of bronchoscopies required. Bronchoscopy with VB navigation yielded high accuracy even for small peripheral pulmonary nodules and shadows that were difficult or impossible to identify on plain x-rays, even for patients in whom earlier conventional bronchoscopy was nondiagnostic.