Virtual endoscopy assisted pure ventriculoscopic resection of cavernomas occluding foramen of Monroe: Technical note and literature review

OBJECTIVE

Cavernomas at Foramen of Monroe (FoM) are rare cases among the intracranial cavernomas. Pure ventriculoscopic removal of cavernoma at FoM through a single burr hole is challenging and rarely reported.

METHODS

We herein introduced the virtual endoscopy (VE) assisted ventriculoscopic resection to treat the cavernomas at FoM. Two cases diagnosed with cavernomas at FoM, a 31-year-old male patient (case 1) and a 26-year-old male patient (case 2), were included. Both of them suffered from headache, nausea and vomiting. The pre-operative MRI revealed masses at the FoM. We reconstructed the VE on a free and open-source platform (3D Slicer) for the pre-surgical evaluation. And then ventriculoscopic operation through a single burr hole was made to remove the cavernomas at FoM.

RESULTS

The VE displayed a 14×19×16 mm lesion in case 1 and an 18×20×29 mm lesion in case 2 and both cases revealed some attachment between the lesions and the periventricular tissue. The ventriculoscopic operations indicated by VE were performed to achieve total resection of the cavernomas without neurological deficit.

CONCLUSIONS

Although the neuroendoscopic treatment to cavernoma at FoM through a single burr hole was rarely reported among the previous literatures, it was a quite effective and useful method in our cases. And the application of VE before ventriculoscopic operation could help to provide a three-dimensional and panorama view of the intraventricular lesions.

Investigation of the applicability of virtual gastroscopy based on postmortem computed tomography to detect changes in the stomach, along with reports of three rare cases

Postmortem computed tomography is now being used more commonly for routine forensic investigation. The use of 3D reconstruction techniques including virtual gastroscopy is effective and also improves the speed of interpretation, recognition, and description of specific clinical conditions. However, it has been unclear whether postmortem virtual endoscopy could be applicable for medicolegal autopsy or whether it could complement pathological examination at autopsy. Here, we investigated the applicability of postmortem virtual gastroscopy by reviewing 295 medicolegal autopsy cases seen at our institution, and found four cases in which the technique had been able to demonstrate features corresponding to changes that were evident at autopsy. Thus,postmortem virtual gastroscopy would have only rarely been effective forvisualizing any change in the stomach in such cases. In addition, we describe in detail three of those cases in which virtual gastroscopy had been able to visualize changes in the stomach, including a gastric ulcer, a polyp, and the presence of foamy fluid, which were all verified at autopsy. In those cases, virtual gastroscopy was useful for understanding features in the stomach of the deceased, which were revealed by axial images of the abdomen, to forensic pathologists who were not familiar with PMCT 2D images. Taken together, our findings suggest that postmortem virtual gastroscopy might help facilitate clear, straightforward sharing of information about PMCT images of complex anatomical structures among radiologists and forensic pathologists, as well as non-medical professionals with a limited knowledge of anatomy and physiology.

Application study of 3D LAVA-Flex on lumbar intervertebral disc degeneration

Background

Degeneration of the intervertebral discs are very common diseases, indicating the specific or malignant changes in intervertebral disc component, structure and function. Imaging examination is currently used to evaluate the severity of lumbar intervertebral disc degeneration. This study was designed to investigate the diagnostic value of 3D LAVA-Flex in lumbar intervertebral disc degeneration.

Material and methods

Sagittal 3D LAVA-Flex and T2WI scans were performed in 45 patients with lumbar intervertebral disc degeneration. On T2WI, the degenerated intervertebral disc in every patient was evaluated using Pfirrmann grade. Then, the patients were re-evaluated using 3D LAVA-Flex with considerations of the distinction of nucleus pulposus and annulus fibrosus, hypointense signal of intervertebral disc and height of intervertebral disc. The evaluation results were compared between 3D LAVA-Flex and T2WI. Virtual endoscopy was also performed to evaluate the degenerated intervertebral disc.

Results

The intermediate–intense signal of nucleus pulposus and complete ring-shaped hyperintense signal of annulus fibrosus were found and the distinction of nucleus pulposus and annulus fibrosus was clear in the normal intervertebral disc on 3D LAVA-Flex. The incidence of linear hypointensity of narrowed intervertebral space (65/91) was higher than that of normal intervertebral space (4/134) (P = 0.000). A good consistency was shown between the LAVA-Flex grade and T2WI-based Pfirrmann grade. Virtual endoscopy based on 3D LAVA-Flex could help clearly show the anatomic relationship between the degenerated disc and intervertebral foramen.

Conclusions

3D LAVA-Flex and T2WI show similar efficacy in evaluating lumbar intervertebral disc degeneration. 3D LAVA-Flex-based virtual endoscopy possesses great potential in the study of intervertebral disc abnormalities.

MR Virtual Endoscopy of the Fetal Limb Anomalies Using Three-Dimensional Fast Imaging Employing Steady-State Acquisition Sequence

OBJECTIVE

To retrospectively investigate the feasibility of magnetic resonance virtual endoscopy (MRVE) to visualize the normal limbs and limb deformities Methods: MR sequences included two-dimensional (2D) single fast spin-echo sequence and 2D and 3D steady-state procession fast imaging sequences. MRVE reconstruction was retrospectively performed by 2 radiologists in 32 fetuses in 30 pregnant women. The correlation between the radiologists for the virtual endoscopy threshold of MRVE was determined. Image quality and limb segment visibility were independently rated. Area under the receiver operating characteristics curve (AUC) of 2D MRI and MRVE was calculated.

RESULTS

The mean virtual endoscopy threshold required for the visualization of the limb was 991.93 ± 12.13 and 991.83 ± 12.26 for 2 radiologists, respectively. The correlation between the radiologists for virtual endoscopy threshold was excellent (r = 0.933). The weighted kappa statistic was 0.96 for the evaluation of image quality of limb segments, indicating excellent interobserver agreement. Compared to that of 2D MRI alone, a higher AUC of 2D MRI with MRVE was achieved in detection of both upper and lower limb deformities (0.91 vs. 0.69 and 0.83 vs. 0.71, respectively).

CONCLUSION

MRVE may display normal and abnormal fetal limb orientation and structures from multiple perspectives and provide incremental information for obstetrics.

Difficult airways: a 3D printing study with virtual fibreoptic endoscopy

Head and neck cancer patients present unique airway challenges, and oropharyngeal, laryngeal, and hypopharyngeal tumours considerably distort and narrow the anatomy of the airway. We describe the use of 3D augmented reality software combined with 3D printed models to assess the anatomy of difficult airways and to assist in the formulation of the most optimal airway management strategy in such patients. The reported patients had computed tomograms (CT) of the neck prior to their anaesthetic and surgical management. DICOM files of the respective scans were imported to 3D rendering software (OsiriX, Pixmeo). We constructed volume rendered models for initial assessment of the airway then generated serial surface rendered models to create a virtual endoscopic path of the airway to simulate the fibreoptic approach. To further facilitate the study of difficult airways we have subsequently printed 3D models of those that were most difficult using rapid prototyping. Head and neck tumours significantly distort the airway. Thorough study of the relevant anatomy prior to airway management for operating reasons enhances communication between the surgeon and anaesthetist, and aids selection of the most appropriate intubation approach. In conclusion, this paper highlights a useful and novel pre-assessment strategy that allows a virtual, visual, 3-dimensional assessment of the airway anatomy combined with 3D modelling and 3D printing. This enables the airway specialist, anaesthetist, and head and neck surgeon to anticipate any critical steps and adjust the plan accordingly.

Three-dimensional imaging of vocalizing larynx by ultra-high-resolution computed tomography

PURPOSE

Ultra-high-resolution computed tomography (UHRCT) is an emerging imaging technology that is able to achieve simultaneous 160 slices with super-thin 0.25 mm thickness. The purpose of this study was to assess the feasibility of UHRCT to visualize laryngeal structure and kinetics.

METHODS

Three normal volunteers and three patients with unilateral vocal fold paralysis (UVFP) were incorporated in this case series. First, images were taken under five conditions in normal volunteers. Five tasks consisted of (1) air inspiration through the nose (IN), (2) breath holding (BH), (3) sustained vowel /i:/ phonation (IP), (4) humming phonation (HP), and (5) forced glottic closure during exhalation (FC). Three-dimensional CT images of arytenoid and cricoid cartilages, as well as virtual laryngoscopic images, were reconstructed using UHRCT data. Reconstructed images were compared among five conditions to assess the best tasks to picture laryngeal kinetics. Second, pre- and post-phonosurgical images were examined in UVFP patients to evaluate potential role of UHRCT to assess laryngeal pathology in hoarse patients.

RESULTS

Among the five conditions, IN and IP conditions were considered suitable to visualize laryngeal structure at rest and during phonation, respectively. Kinetic abnormalities including asymmetric motion of arytenoid cartilages were elucidated in UVFP patients, and virtual endoscopy visualized the clinically invisible posterior three-dimensional glottic chinks. Furthermore, UHRCT was useful to understand changes in laryngeal structure achieved by phonosurgery.

CONCLUSIONS

UHRCT is an emerging imaging technology that can be used for minimally invasive visualization and assessment of laryngeal structure and kinetics. Future studies to assess more number of patients with laryngeal dysfunction are warranted.

A review of virtual reality simulators for neuroendoscopy

Neurosurgery is a challenging surgical specialty that demands many technical and cognitive skills. The traditional surgical training approach of having a trainee coached in the operating room by the faculty is time-consuming, costly, and involves patient risk factors. Simulation-based training methods are suitable to impart the surgical skills outside the operating room. Virtual simulators allow high-fidelity repeatable environment for surgical training. Neuroendoscopy, a minimally invasive neurosurgical technique, demands additional skills for limited maneuverability and eye-hand coordination. This study provides a review of the existing virtual reality simulators for training neuroendoscopic skills. Based on the screening, the virtual training methods developed for neuroendoscopy surgical skills were classified into endoscopic third ventriculostomy and endonasal transsphenoidal surgery trainers. The study revealed that a variety of virtual reality simulators have been developed by various institutions. Although virtual reality simulators are effective for procedure-based skills training, the simulators need to include anatomical variations and variety of cases for improved fidelity. The review reveals that there should be multi-centric prospective and retrospective cohort studies to establish concurrent and predictive validation for their incorporation in the surgical educational curriculum.

Reconstruction of esophageal stenosis that had persisted for 40 years using a free jejunal patch graft with virtual endoscopy assistance: A case report

In this report, we present a case in which good results were achieved by treatment using a free jejunal patch graft with virtual endoscopy (VE) assistance in a patient whose swallowing had failed to improve for 40 years after he mistakenly swallowed sulfuric acid, despite pectoralis major myocutaneous flap grafting and frequent balloon dilatation surgery. During the last 20 years, virtual computed tomography imaging has improved remarkably and continues to be used to address new challenges. For reconstructive surgeons, the greatest advantage of VE is that it is a noninvasive modality capable of visualizing areas inaccessible to a flexible endoscope. Using VE findings, we were able to visualize the 3-dimensional shape beyond the stenosis. VE can also help predict the area of the defect after contracture release.

Visualization Within the Ventricles of the Brain: A Micro-Focus X-Ray Study

Conceptualization of the ventricular system of the brain by macroscopic studies is complicated by the lack of physical structure of these interconnected cavities. Dissection procedures designed to display the structures in the walls of the ventricles are destructive and not conducive for the appreciation of the ventricular system in its entirety. The application of Micro-focus X-ray tomography affords the possibility to appreciate hidden structures in a nondestructive manner. The aim of this study was to explore the possibility of using micro-focus X-ray tomography in the three-dimensional (3D) visualization of the ventricular system as well as the various neuroanatomical structures within its walls for educational purposes. Randomly selected embalmed human cadaver brains were scanned at Necsa (South African Nuclear Energy Corporation) housing the MIXRAD laboratory consisting of a Nikon XTH 225 ST micro-focus X-ray tomography facility. A 3D flythrough video of the ventricular system was reconstructed from these scans using software to view the inner surface of the ventricles. Micro-focus X-ray tomography provides feasible means of delivering high-resolution images in a nondestructive way to design a representation of the ventricular system. In addition, structures in the walls of the ventricular system could be appreciated in a novel way. It is envisaged that this 3D-fly-through video of the ventricular system will be valuable when integrated with standard prosections and atlas pictures in the educational setting. Further studies evaluating the use of this integrative visualization of the ventricular system of the brain for its applicability in the educational setting should be performed. Anat Rec, 301:1138-1147, 2018. © 2017 Wiley Periodicals, Inc.

Ultrasound virtual endoscopy: Polyp detection and reliability of measurement in an in vitro study with pig intestine specimens

AIM: To present our initial experience regarding the feasibility of ultrasound virtual endoscopy (USVE) and its measurement reliability for polyp detection in an in vitro study using pig intestine specimens.

METHODS: Six porcine intestine specimens containing 30 synthetic polyps underwent USVE, computed tomography colonography (CTC) and optical colonoscopy (OC) for polyp detection. The polyp measurement defined as the maximum polyp diameter on two-dimensional (2D) multiplanar reformatted (MPR) planes was obtained by USVE, and the absolute measurement error was analyzed using the direct measurement as the reference standard.

RESULTS: USVE detected 29 (96.7%) of 30 polyps, remaining a 7-mm one missed. There was one false-positive finding. Twenty-six (89.7%) of 29 reconstructed images were clearly depicted, while 29 (96.7%) of 30 polyps were displayed on CTC with one false-negative finding. In OC, all the polyps were detected. The intraclass correlation coefficient was 0.876 (95%CI: 0.745-0.940) for measurements obtained with USVE. The pooled absolute measurement errors ± the standard deviations of the depicted polyps with actual sizes ≤ 5 mm, 6-9 mm, and ≥ 10 mm were 1.9 ± 0.8 mm, 0.9 ± 1.2 mm, and 1.0 ± 1.4 mm, respectively.

CONCLUSION: USVE is reliable for polyp detection and measurement in in vitro study.

Low-Cost Interactive Image-Based Virtual Endoscopy for the Diagnosis and Surgical Planning of Suprasellar Arachnoid Cysts

OBJECTIVE

To investigate the feasibility and reliability of virtual endoscopy (VE) as a rapid, low-cost, and interactive tool for the diagnosis and surgical planning of suprasellar arachnoid cysts (SACs).

METHODS

Eighteen patients with SACs treated with endoscopic ventriculocystostomy were recruited, and 18 endoscopic patients treated with third ventriculostomy were randomly selected as a VE reconstruction control group. After loading their DICOM data into free 3D Slicer software, VE reconstruction was independently performed by 3 blinded clinicians and the time required for each reconstruction was recorded. Another 3 blinded senior neurosurgeons interactively graded the visibility of VE by watching video recordings of the endoscopic procedures. Based on the visibility scores, receiver operating characteristic curve analysis was used to investigate the reliability of VE to diagnose SACs, and Bland-Altman plots were used to assess the reliability of VE for surgical planning. In addition, the intraclass correlation coefficient was calculated to estimate the consistency among the results of 3 reconstruction performers.

RESULTS

All 3 independent reconstructing performers successfully completed VE simulation for all cases, and the average reconstruction time was 10.2 ± 9.7 minutes. The area under the receiver operating characteristic curve of the cyst visibility score was 0.96, implying its diagnostic value for SACs. The Bland-Altman plot indicated good agreement between VE and intraoperative viewings, suggesting the anatomic accuracy of the VE for surgical planning. In addition, the intraclass correlation coefficient was 0.81, which revealed excellent interperformer consistency of our simulation method.

CONCLUSIONS

This study substantiated the feasibility and reliability of VE as a rapid, low-cost, and interactive modality for diagnosis and surgical planning of SACs.

Application of MR virtual endoscopy in children with hydrocephalus

PURPOSE

To evaluate the performance of MR virtual endoscopy (MRVE) in children with hydrocephalus.

MATERIALS AND METHODS

Clinical and imaging data were collected from 15 pediatric patients with hydrocephalus and 15 normal control children. All hydrocephalus patients were confirmed by ventriculoscopy or CT imaging. The cranial 3D-T1 weighted imaging data from fast spoiled gradient echo scan (FSPGR) were transported to working station. VE images of cerebral ventricular cavity were constructed with Navigator software.

RESULTS

Cerebral ventricular MRVE can achieve similar results as ventriculoscopy in demonstrating the morphology of ventricular wall or intracavity lesion. In addition, MRVE can observe the lesion from distal end of obstruction, as well as other areas that are inaccessible to ventriculoscopy. MRVE can also reveal the pathological change of ventricular inner wall surface, and help determine patency of the cerebral aqueduct and fourth ventricle outlet.

CONCLUSION

MR virtual endoscopy provides a non-invasive diagnostic modality that can be used as a supplemental approach to ventriculoscopy. However, its sensitivity and specificity need to be determined in the large study.

The role of three-dimensional multidetector CT gastrography in the preoperative imaging of stomach cancer: emphasis on detection and localization of the tumor

Multidetector CT (MDCT) gastrography has been regarded as a promising technique for the preoperative imaging of gastric cancer. It has the ability to produce various three-dimensional (3D) images. Because 3D reconstruction images are more effective and intuitive for recognizing abnormal changes in the gastric folds and subtle mucosal nodularity than two-dimensional images, 3D MDCT gastrography can enhance the detection rate of early gastric cancer, which, in turn, contributes to the improvement of the accuracy of preoperative tumor (T) staging. In addition, shaded surface display and tissue transition projection images provide a global view of the stomach, with the exact location of gastric cancer, which may replace the need for barium studies. In this article, we discuss technical factors in producing high-quality MDCT gastrographic images and present cases demonstrating the usefulness of MDCT gastrography for the detection and T staging of gastric cancer while emphasizing the significance of preoperative localization of gastric cancer in terms of surgical margin.

Evaluation of velopharyngeal closure by 4D imaging using 320-detector-row computed tomography

OBJECTIVE

Current imaging techniques for velopharyngeal closure (VPC) evaluation are two-dimensional, static, or distressing, thus necessitating multiple procedures to understand this three-dimensional and dynamic area. We validated the use of a novel four-dimensional (4D) computed tomography (CT) technique for the morphological and kinematic evaluation of VPC in cleft palate patients based on dynamic volume scanning with 320-detector-row CT.

METHODS

Five patients aged 4-10 years (40% males) with persistent velopharyngeal insufficiency post palatoplasty underwent conventional tests (cephalometry and video-nasal endoscopy) and 4D-CT. For each patient, complete multiplanar reconstruction, 4D airway CT, and 4D-CT endoscopy data for all scanning phases were compared with cephalometric and video-nasal endoscopy data. The movements of the velum and posterior pharyngeal walls were graded by each modality.

RESULTS

4D airway CT revealed higher anatomical detail than cephalometry, additionally providing dynamic images. 4D-CT endoscopy and video-nasal endoscopy were in agreement for all patients regarding the patterns of VPC, with complete visualization of VPC in five versus one patient, respectively. 4D airway CT and cephalometry showed a discrepancy in one case, wherein grading by cephalometry was overestimated. 4D-CT was also useful in determining the width and length of a proposed pharyngeal flap. The examination time (mean ± standard deviation (SD), seconds), including patient preparation time, was 224 ± 73, 492 ± 145, and 718 ± 123 for cephalometric radiographs, CT, and video-nasal endoscopy, respectively. The mean estimated radiation dose during 4D-CT was 4.44 ± 1.64 mSv.

CONCLUSIONS

4D-CT provides detailed morphological and kinematic analysis of VPC and may offer advantages over conventional procedures.

Computed tomography virtual endoscopy with angiographic imaging for the treatment of type IV-A choledochal cyst

Type IV-A choledochal cysts (CCs) are a congenital biliary anomaly which involve dilatation of the extrahepatic and intrahepatic bile ducts. We present the case of a 30-year-old woman with type IV-A CC, on whom three-dimensional computed tomography (3D CT) and virtual endoscopy were performed. 3D CT revealed partial dilatation in the posterior branch of the intrahepatic bile duct and a relative stricture between it and the extrahepatic bile duct. Virtual endoscopy showed that this stricture was membrane-like and separated from the surrounding blood vessels. Based on these image findings, complete cyst resection, bile duct plasty for the stricture, and hepaticojejunostomy were safely performed. To the best of our knowledge, there are no reports of imaging by virtual endoscopy of the biliary tract which show the surrounding blood vessels running along the bile duct.

Sonography of the small intestine

In the last two decades, there has been substantial development in the diagnostic possibilities for examining the small intestine. Compared with computerized tomography, magnetic resonance imaging, capsule endoscopy and double-balloon endoscopy, ultrasonography has the advantage of being cheap, portable, flexible and user- and patient-friendly, while at the same time providing the clinician with image data of high temporal and spatial resolution. The method has limitations with penetration in obesity and with intestinal air impairing image quality. The flexibility ultrasonography offers the examiner also implies that a systematic approach during scanning is needed. This paper reviews the basic scanning techniques and new modalities such as contrast-enhanced ultrasound, elastography, strain rate imaging, hydrosonography, allergosonography, endoscopic sonography and nutritional imaging, and the literature on disease-specific findings in the small intestine. Some of these methods have shown clinical benefit, while others are under research and development to establish their role in the diagnostic repertoire. However, along with improved overall image quality of new ultrasound scanners, these methods have enabled more anatomical and physiological changes in the small intestine to be observed. Accordingly, ultrasound of the small intestine is an attractive clinical tool to study patients with a range of diseases.

Colorectal neoplasm: Magnetic resonance colonography with fat enema-initial clinical experience

AIM: To assess Magnetic resonance colonography with fat enema as a method for detection of colorectal neoplasm.

METHODS: Consecutive twenty-two patients underwent MR colonography with fat enema before colonoscopy. T1-weighted three-dimensional fast spoiled gradient-echo with inversion recovery sequence was acquired with the patient in the supine position before and 75 s after Gadopentetate Dimelumine administration. Where by, pre and post MR coronal images were obtained with a single breath hold for about 20 s to cover the entire colon. The quality of MR colonographs and patients' tolerance to fat contrast medium was investigated. Colorectal neoplasms identified by MR colonography were compared with those identified on colonoscopy and sensitivity of detecting the lesions was calculated accordingly.

RESULTS: MR colonography with fat enema was well tolerated without sedation and analgesia. 120 out of 132 (90.9%) colonic segments were well distended and only 1 (0.8%) colonic segment was poor distension. After contrast enhancement scan, mean contrast-to-noise ratio (CNR) value between the normal colonic wall and lumen was 18.5 ± 2.9 while mean CNR value between colorectal neoplasm and lumen was 20.2 ± 3.1. By Magnetic resonance colonography, 26 of 35 neoplasms (sensitivity 74.3%) were detected. However, sensitivity of MRC was 95.5% (21 of 22) for neoplasm larger than 10 mm and 55.6% (5 of 9) for 5-10 mm neoplasm.

CONCLUSION: MR colonography with fat enema and T1-weighted three-dimensional fast spoiled gradient-echo with inversion recovery sequence is feasible in detecting colorectal neoplasm larger than 10 mm.

Congenital tracheoesophageal fistula successfully diagnosed by CT esophagography

Tracheoesophageal fistula (TEF) or bronchoesophageal fistula may be congenital, inflammatory, neoplastic, or secondary to trauma. Congenital TEF or bron-choesophageal fistula is usually associated with eso-phageal atresia and is readily diagnosed in infancy. But if it is not associated with esophageal atresia, it may persist until adulthood. Some theories have been proposed to explain this delay in diagnosis. We present a case of a 70-year-old man with congenital TEF. The TEF was successfully diagnosed by multidetector-row CT esophagography.