Virtual Endoscopic Images Research Articles

Application of virtual endoscopic imaging to parapelvic cyst incision by flexible ureteroscopy: a multicenter retrospective cohort study.

A three-dimensional (3D) reconstruction of the kidney, parapelvic cyst and the collecting system was conducted using the 3D Slicer software. The reconstructed image was used to form a virtual endoscope to assist flexible ureteroscopic incision and drainage was performed with a holmium laser for treating parapelvic cysts. The effectiveness of this assistive technique was assessed. This was a retrospective cohort study. The clinical information of 59 patients undergoing flexible ureteroscopic incision and drainage for parapelvic cysts in two medical centers was collected. 3D Slicer software reconstruction and virtual endoscopic imaging were performed for 28 cases. Before the operation, the best point for incision on the collecting system's mucosa was assessed by virtual endoscope imaging. Propensity score matching was adopted for the reconstructive and non-reconstructive groups. After matching, the reconstructive group and non-reconstructive group both had 21 cases each. The operation time in the reconstructive and non-reconstructive groups was 38.81±5.01 and 51.00±18 minutes, respectively. Statistically significant differences existed between the two groups (t=7.024, P<0.001). No statistical significance was found in postoperative fever, immediate postoperative C reactive protein (CRP), length of postoperative hospital stay and cyst diameter three months after the operation. The operator was provided with a more direct and real vision when 3D Slicer software reconstruction was adopted via virtual endoscopic imaging to assist flexible ureteroscopic parapelvic cyst incision. This helped reduce the operation time. Further follow-ups and observations are required to assess the long-term efficacy of flexible ureteroscopic parapelvic cyst incision.

Endoscopic Transnasal Resection for Chordoma Invaded to Lower-Third Clivus-Usefulness of Preoperative Simulation With Virtual Endoscopic Imaging: 2-Dimensional Operative Video.

Endoscopic Transnasal Resection for Chordoma Invaded to Lower-Third Clivus-Usefulness of Preoperative Simulation With Virtual Endoscopic Imaging: 2-Dimensional Operative Video.

Added Value of Computed Tomography Virtual Intravascular Endoscopy in the Evaluation of Coronary Arteries with Stents or Plaques.

Coronary computed tomography angiography (CCTA) is a widely used imaging modality for diagnosing coronary artery disease (CAD) but is limited by a high false positive rate when evaluating coronary arteries with stents and heavy calcifications. Virtual intravascular endoscopy (VIE) images generated from CCTA can be used to qualitatively assess the vascular lumen and might be helpful for overcoming this challenge. In this study, one hundred subjects with coronary stents underwent both CCTA and invasive coronary angiography (ICA). A total of 902 vessel segments were analyzed using CCTA and VIE. The vessel segments were first analyzed on CCTA alone. Then, using VIE, the segments were classified qualitatively as either negative or positive for in-stent restenosis (ISR) or CAD. These results were compared, using ICA as the reference, to determine the added diagnostic value of VIE. Of the 902 analyzed vessel segments, CCTA/VIE had sensitivity, specificity, accuracy, positive predictive value, and negative predictive value (shown in %) of 93.9/90.2, 96.2/98.2, 96.0/97.7, 70.0/83.1, and 99.4/99.0, respectively, in diagnosing ISR or CAD, with significantly improved specificity (p = 0.025), accuracy (p = 0.046), and positive predictive value (p = 0.047). VIE can be a helpful addition to CCTA when evaluating coronary arteries.

Preoperative perihilar cholangiocarcinoma assessment using virtual endoscopic imaging magnetic resonance cholangioscopy.

Background and study aims Preoperative assessment of the superficial ductal spread (SDS) of perihilar cholangiocarcinoma (PCCA) is important for determining its resectability. A virtual endoscopic imaging method, magnetic resonance cholangioscopy (MRCS), wherein a three-dimensional image is created from magnetic resonance imaging (MRI) data, can evaluate all aspects of arbitrary bile ducts. Patients and methods Overall, 15 patients with PCCA who underwent preoperative MRI were enrolled. All patients underwent surgical treatment. Results MRCS could be performed based on preoperative MRI data in all patients. MRCS could not be used in one patient due to debris in the obstructed bile duct. The remaining 14 patients (93 %) were diagnosed with obstructed bile duct or irregular surface of the bile duct, signifying tumor invasion. The accuracy rate of diagnosing the SDS was 93 % (14/15). Seven patients underwent preoperative peroral cholangioscopy; the scope could not pass through the tumor in three patients. In these three patients, MRCS was able to be use dtoevaluate the obstructed side of the bile duct and faciliated accurate diagnosis of SDS. Conclusions MRCS can be used to noninvasively evaluate the bile duct in all directions. This novel method makes it easy to create virtual images and can be useful for diagnosing the preoperative SDS of PCCA.

Realistic endoscopic image generation method using virtual-to-real image-domain translation.

A realistic image generation method for visualisation in endoscopic simulation systems is proposed in this study. Endoscopic diagnosis and treatment are performed in many hospitals. To reduce complications related to endoscope insertions, endoscopic simulation systems are used for training or rehearsal of endoscope insertions. However, current simulation systems generate non-realistic virtual endoscopic images. To improve the value of the simulation systems, improvement of the reality of their generated images is necessary. The authors propose a realistic image generation method for endoscopic simulation systems. Virtual endoscopic images are generated by using a volume rendering method from a CT volume of a patient. They improve the reality of the virtual endoscopic images using a virtual-to-real image-domain translation technique. The image-domain translator is implemented as a fully convolutional network (FCN). They train the FCN by minimising a cycle consistency loss function. The FCN is trained using unpaired virtual and real endoscopic images. To obtain high-quality image-domain translation results, they perform an image cleansing to the real endoscopic image set. They tested to use the shallow U-Net, U-Net, deep U-Net, and U-Net having residual units as the image-domain translator. The deep U-Net and U-Net having residual units generated quite realistic images.

Personalized 3D printed coronary models in coronary stenting

3D printing has shown great promise in cardiovascular disease, with reports mainly focusing on pre-surgical planning and medical education. Research on utilization of 3D printed models in simulating coronary stenting has not been reported. In this study, we presented our experience of placing coronary stents into personalized 3D printed coronary models with the aim of determining stent lumen visibility with images reconstructed with different postprocessing views and algorithms. A total of six coronary stents with diameter ranging from 2.5 to 4.0 mm were placed into 3 patient-specific 3D printed coronary models for simulation of coronary stenting. The 3D printed models were placed in a plastic container and scanned on a 192-slice third generation dual-source CT scanner with images reconstructed with soft (Bv36) and sharp (Bv59) kernel algorithms. Thick and thin slab maximum-intensity projection (MIP) images were also generated from the original CT data for comparison of stent lumen visibility. Stent lumen diameter was measured on 2D axial and MIP images, while stent diameter was measured on 3D volume rendering images. 3D virtual intravascular endoscopy (VIE) images were generated to provide intraluminal views of the coronary wall and stent appearances. All of these stents were successfully placed into the right and left coronary arteries but 2 of them did not obtain wall apposition along the complete length. The stent lumen visibility ranged from 54 to 97%, depending on the stent location in the coronary arteries. The mean stent lumen diameters measured on 2D axial, thin and thick slab MIP images were found to be significantly smaller than the actual size (P<0.01). Thick slab MIP images resulted in measured stent lumen diameters smaller than those from thin slab MIP images, with significant differences noticed in most of the measurements (4 out of 6 stents) (P<0.05), and no significant differences in the remaining 2 stents (P=0.19-0.38). In contrast, 3D volume rendering images allowed for more accurate measurements with measured stent diameters close to the actual dimensions in most of these coronary stents, except for the stent placed at the right coronary artery in one of the models due to insufficient expansion of the stent. Images reconstructed with sharp kernel Bv59 significantly improved stent lumen visibility when compared to the smooth Bv36 kernel (P=0.01). 3D VIE was successfully generated in all of the datasets with clear visualization of intraluminal views of the stents in relation to the coronary wall. This preliminary report shows the feasibility of using 3D printed coronary artery models in coronary stenting for investigation of optimal coronary CT angiography protocols. Future studies should focus on placement of more stents with a range of stent diameters in the quest to reduce the need for invasive angiography for surveillance.

Optimization of computed tomography pulmonary angiography protocols using 3D printed model with simulation of pulmonary embolism.

Three-dimensional (3D) printing has been shown to accurately replicate anatomical structures and pathologies in complex cardiovascular disease. Application of 3D printed models to simulate pulmonary arteries and pulmonary embolism (PE) could assist development of computed tomography pulmonary angiography (CTPA) protocols with low radiation dose, however, this has not been studied in the literature. The aim of this study was to investigate optimal CTPA protocols for detection of PE based on a 3D printed pulmonary model. A patient-specific 3D printed pulmonary artery model was generated with thrombus placed in both main pulmonary arteries to represent PE. The model was scanned with 128-slice dual-source CT with slice thickness of 1 and 0.5 mm reconstruction interval. The tube voltage was selected to range from 70, 80, 100 to 120 kVp, and pitch value from 0.9 to 2.2 and 3.2. Quantitative assessment of image quality in terms of signal-to-noise ratio (SNR) was measured in the main pulmonary arteries and within the thrombus regions to determine the relationship between image quality and scanning protocols. Both two-dimensional (2D) and 3D virtual intravascular endoscopy (VIE) images were generated to demonstrate pulmonary artery and thrombus appearances. PE was successfully simulated in the 3D printed pulmonary artery model. There were no significant differences in SNR measured in the main pulmonary arteries with 100 and 120 kVp CTPA protocols (P>0.05), regardless of pitch value used. SNR was significantly lower in the high-pitch 3.2 protocols when compared to other protocols using 70 and 80 kVp (P<0.05). There were no significant differences in SNR measured within the thrombus among the 100 and 120 kVp protocols (P>0.05). For low dose 70 and 80 kVp protocols, SNR was significantly lower in the high-pitch of 3.2 protocols than that in other protocols with different pitch values (P<0.01). 2D images showed the pulmonary arteries and thrombus clearly, while 3D VIE demonstrated intraluminal appearances of pulmonary wall and thrombus in all protocols, except for the 70 kVp and pitch 3.2 protocol, with visualization of thrombus and pulmonary artery wall affected by artifact associated with high image noise. Radiation dose was reduced by up to 80% when lowering kVp from 120 to 100 and 80 kVp with use of 3.2 high-pitch protocol, without significantly affecting image quality. Low-dose CT pulmonary angiography can be achieved with use of low kVp (80 and 100) and high-pitch protocol with significant reduction in radiation dose while maintaining diagnostic images of PE. Use of high pitch, 3.2 in 70 kVp protocol should be avoided due to high image noise and poorer quality.

The influence of non-rigid anatomy and patient positioning on endoscopy-CT image registration in the head and neck.

To assess the influence of non-rigid anatomy and differences in patient positioning between CT acquisition and endoscopic examination on endoscopy-CT image registration in the head and neck. Radiotherapy planning CTs and 31-35 daily treatment-room CTs were acquired for nineteen patients. Diagnostic CTs were acquired for thirteen of the patients. The surfaces of the airways were segmented on all scans and triangular meshes were created to render virtual endoscopic images with a calibrated pinhole model of an endoscope. The virtual images were used to take projective measurements throughout the meshes, with reference measurements defined as those taken on the planning CTs and test measurements defined as those taken on the daily or diagnostic CTs. The influence of non-rigid anatomy was quantified by 3D distance errors between reference and test measurements on the daily CTs, and the influence of patient positioning was quantified by 3D distance errors between reference and test measurements on the diagnostic CTs. The daily CT measurements were also used to investigate the influences of camera-to-surface distance, surface angle, and the interval of time between scans. Average errors in the daily CTs were 0.36±0.61cm in the nasal cavity, 0.58±0.83cm in the naso- and oropharynx, and 0.47±0.73cm in the hypopharynx and larynx. Average errors in the diagnostic CTs in those regions were 0.52±0.69cm, 0.65±0.84cm, and 0.69±0.90cm, respectively. All CTs had errors heavily skewed towards 0, albeit with large outliers. Large camera-to-surface distances were found to increase the errors, but the angle at which the camera viewed the surface had no effect. The errors in the Day 1 and Day 15 CTs were found to be significantly smaller than those in the Day 30 CTs (P<0.05). Inconsistencies of patient positioning have a larger influence than non-rigid anatomy on projective measurement errors. In general, these errors are largest when the camera is in the superior pharynx, where it sees large distances and a lot of muscle motion. The errors are larger when the interval of time between CT acquisitions is longer, which suggests that the interval of time between the CT acquisition and the endoscopic examination should be kept short. The median errors found in this study are comparable to acceptable levels of uncertainty in deformable CT registration. Large errors are possible even when image alignment is very good, indicating that projective measurements must be made carefully to avoid these outliers.

The feasibility of endoscopy-CT image registration in the head and neck without prospective endoscope tracking.

PurposeEndoscopic examinations are frequently-used procedures for patients with head and neck cancer undergoing radiotherapy, but radiation treatment plans are created on computed tomography (CT) scans. Image registration between endoscopic video and CT could be used to improve treatment planning and analysis of radiation-related normal tissue toxicity. The purpose of this study was to explore the feasibility of endoscopy-CT image registration without prospective physical tracking of the endoscope during the examination.MethodsA novel registration technique called Location Search was developed. This technique uses physical constraints on the endoscope’s view direction to search for the virtual endoscope coordinates that maximize the similarity between the endoscopic video frame and the virtual endoscopic image. Its performance was tested on phantom and patient images and compared to an established registration technique, Frame-To-Frame Tracking.ResultsIn phantoms, Location Search had average registration errors of 0.55 ± 0.60 cm for point measurements and 0.29 ± 0.15 cm for object surface measurements. Frame-To-Frame Tracking achieved similar results on some frames, but it failed on others due to the virtual endoscope becoming lost. This weakness was more pronounced in patients, where Frame-To-Frame tracking could not make it through the nasal cavity. On successful patient video frames, Location Search was able to find endoscope positions with an average distance of 0.98 ± 0.53 cm away from the ground truth positions. However, it failed on many frames due to false similarity matches caused by anatomical structural differences between the endoscopic video and the virtual endoscopic images.ConclusionsEndoscopy-CT image registration without prospective physical tracking of the endoscope is possible, but more development is required to achieve an accuracy suitable for clinical translation.

MDCT imaging of the stomach: advances and applications.

The stomach may be involved by a myriad of pathologies ranging from benign aetiologies like inflammation to malignant aetiologies like carcinoma or lymphoma. Multidetector CT (MDCT) of the stomach is the first-line imaging for patients with suspected gastric pathologies. Conventionally, CT imaging had the advantage of simultaneous detection of the mural and extramural disease extent, but advances in MDCT have allowed mucosal assessment by virtual endoscopy (VE). Also, better three-dimensional (3D) post-processing techniques have enabled more robust and accurate pre-operative planning in patients undergoing gastrectomy and even predict the response to surgery for patients undergoing laparoscopic sleeve gastrectomy for weight loss. The ability of CT to obtain stomach volume (for bariatric surgery patients) and 3D VE images depends on various patient and protocol factors that are important for a radiologist to understand. We review the appropriate CT imaging protocol in the patients with suspected gastric pathologies and highlight the imaging pearls of various gastric pathologies on CT and VE.

TU‐AB‐202‐12: A Novel Method to Map Endoscopic Video to CT for Treatment Planning and Toxicity Analysis in Radiation Therapy

Purpose:Endoscopic examinations are routine procedures for head‐and‐neck cancer patients. Our goal is to develop a method to map the recorded video to CT, providing valuable information for radiotherapy treatment planning and toxicity analysis.Methods:We map video frames to CT via virtual endoscopic images rendered at the real endoscope's CT‐space coordinates. We developed two complementary methods to find these coordinates by maximizing real‐to‐virtual image similarity:(1)Endoscope Tracking: moves the virtual endoscope frame‐by‐frame until the desired frame is reached. Utilizes prior knowledge of endoscope coordinates, but sensitive to local optima. (2)Location Search: moves the virtual endoscope along possible paths through the volume to find the desired frame. More robust, but more computationally expensive. We tested these methods on clay phantoms with embedded markers for point mapping and protruding bolus material for contour mapping, and we assessed them qualitatively on three patient exams. For mapped points we calculated 3D‐distance errors, and for mapped contours we calculated mean absolute distances (MAD) from CT contours.Results:In phantoms, Endoscope Tracking had average point error=0.66±0.50cm and average bolus MAD=0.74±0.37cm for the first 80% of each video. After that the virtual endoscope got lost, increasing these values to 4.73±1.69cm and 4.06±0.30cm. Location Search had point error=0.49±0.44cm and MAD=0.53±0.28cm. Point errors were larger where the endoscope viewed the surface at shallow angles&lt;10 degrees (1.38±0.62cm and 1.22±0.69cm for Endoscope Tracking and Location Search, respectively). In patients, Endoscope Tracking did not make it past the nasal cavity. However, Location Search found coordinates near the correct location for 70% of test frames. Its performance was best near the epiglottis and in the nasal cavity.Conclusion:Location Search is a robust and accurate technique to map endoscopic video to CT. Endoscope Tracking is sensitive to erratic camera motion and local optima, but could be used in conjunction with anchor points found using Location Search.

Value of virtual endoscopy in diagnosis and treatment for hydrocephalus after failed shunt

To investigate the value of virtual endoscopy in diagnosis and treatment of hydrocephalus after failed shunt. we performed magnetic resonance imaging (MRI) 3D-SPACE sequence scanning for 76 patients suffering from hydrocephalus after failed shunt. Based on the DICOM data of 3D-SPACE sequence, we three-dimensionally reconstructed the ventricles and simulated virtual endoscopy with 3D-Slicer software. Surgical strategy was made after evaluation of virtual endoscopy images. Virtual endoscopy based on 3D-SPACE images was helpful to depict the aqueduct or foramen of Monro obstructions, and confirm the reason of shunt failure. Finally, there were 56 hydrocephalus patients (73.7%) were treated with endoscopic assisted third ventricle fistula (ETV), without shunt catheter insertion. For patients suffering from shunt failure of hydrocephalus, virtual endoscopy has high diagnostic yield rate for providing more detailed anatomical information than conventional MR imaging. Hence, this advanced imaging method is helpful for surgical treatment strategy decision making.

Virtual Bronchoscopy Using OsiriX

Although the utility of virtual bronchoscopy has been reported, the software for virtual bronchoscopy has not been popular because of the high cost. OsiriX is a reasonably priced software that is available to reconstruct virtual endoscopic images. Herein, we present the ability of OsiriX to enable virtual bronchoscopy. Computed tomography of the chest was performed using a 16-row multidetector. Data in 2 mm slices from one lung were obtained from 10 patients with a lung nodule. Virtual bronchoscopic images were established by OsiriX version 5.5 (32-bit). To examine the ability to visualize small bronchi, we tried to visualize the distal bronchus if possible. We selected B and B for the right lung and B and B for the left lung. In addition, to predict whether a pathologic diagnosis can successfully be made by transbronchial lung biopsy, we reconstructed virtual bronchoscopic images toward the lung nodule. Bronchoscopic images were successfully reconstructed for all patients. The third to the seventh bronchi were visualized except in one patient whose right B was occluded by a tumor. In all patients, the virtual bronchoscopic path reached the lung nodule, and 5 lung nodules were successfully diagnosed by transbronchial biopsy. OsiriX is practicable for virtual bronchoscopy at a low cost.

The CT and intraoperative observation of pedicel-ossification tunnel in 151 cases of thoracic spinal stenosis from ossification of ligamentum flavum

The aim of this study is to precisely illustrate the pedicle-ossification tunnel (POT)-a spinal cord-free pathway in upper facet joint en bloc resection, which was reported as a comparatively neurological safer decompression surgery for thoracic ossification of ligamentum flavum (OLF). From 1998 to 2009, 151 patients with thoracic spinal stenosis from OLF were diagnosed by CT, MRI, neurological examinations and confirmed by postoperative pathological examination. The existence and configuration of the POT were observed by interactive CT virtual endoscopic (CTVE) image with multiplanar reconstructions and confirmed by intraoperative observation. Posterior decompression by upper facet joint en bloc resection via POT was conducted in all patients and the advantage of surgery was evaluated by modified Japanese Orthopedic Association scores pre- and post-operatively. Through CTVE and intraoperative observation, no spinal cord was found present in POTs. OLF bloc divided the foramen into three parts: upper POT, OLF bloc and lower POT. The POT was the epidural space between the lateral border of OLF and its neighboring pedicles inner cortex. The recovery rate of upper facet joint en bloc resection via POT was 75.24 ± 18.01 %. POT is a spinal cord-free pathway between OLF bloc and its neighboring pedicles in thoracic spinal stenosis which can be applied in neuron preserved decompression surgery.

Usefulness of multi‐3‐dimensional computed tomograms fused with multiplanar reconstruction images and peroral cholangioscopy findings in hilar cholangiocarcinoma

Multiplanar reconstruction (MPR) images are used for assessing horizontal and vertical extent of hilar cholangiocarcinoma, while peroral cholangioscopy (POCS) is used for diagnosing ductal spread and mapping biopsy. We fused conventional 3-dimensional computed tomography (3DCT) with MPR images and POCS findings for preoperative assessment of cholangiocarcinoma. The extent of cancer was assessed using MPR images, which were plotted and fused onto 3DCT cholangiography. In addition, the results of mapping biopsy performed under POCS were marked on virtual endoscopic imaging and transferred onto a 3DCT image. Once an angiographic CT image was fused, a multi-3DCT image was created. The incision line was determined based on these images. Multi-3DCT images were created for 13 patients with hilar cholangiocarcinoma. Of 10 patients who underwent POCS, superficial spread was observed in two. Resection was performed in 12 patients. In two cases, the cut end of the intrahepatic bile duct was positive, resulting in 83.3% diagnostic accuracy for horizontal spread. In all patients, the estimated number of bile ducts was the same as the number of the actual resections. R0 resection was achieved in 10 patients (83.3%). Multi-3DCT imaging proved useful in diagnosing longitudinal ductal spread of hilar cholangiocarcinoma.

Laterally spreading tumors: limitations of computed tomography colonography.

To prospectively investigate the detection rate of laterally spreading tumors (LSTs) of the colorectum by computed tomography (CT) colonography (CTC). Patients with LSTs measuring ≥ 20 mm detected during colonoscopy were prospectively enrolled in the study. All patients underwent colonoscopy and subsequent CTC on the same day. CTC was performed using multi-detector CT without contrast in the prone and supine positions. Two radiologists blinded to the existence of LSTs read the virtual endoscopic images as well as 2-D images. LSTs were classified into granular and non-granular types based on colonoscopic appearance. Forty-seven pathologically proven LSTs were evaluated prospectively. Histology included adenomas in 19, mucosal cancers in 19 and T1 cancers in 9. The mean diameter of the LSTs was 35.1 mm. Twenty-eight (60%) LSTs were correctly identified by CTC, and the configuration was similar to the colonoscopic appearance in most cases. Detection rate for the granular type was significantly higher than that for the non-granular type (71% vs 31%, P = 0.013). Detection rate of adenomas was significantly lower than mucosal cancers (32% vs 79%, P = 0.008) and T1 cancers (32% vs 78%, P = 0.042). The detection rate of LSTs by CTC, particularly the non-granular type was not acceptable. Practitioners should be aware of the relatively low detection rate when using CTC.

MDCT in the Assessment of Laryngeal Trauma: Value of 2D Multiplanar and 3D Reconstructions

The purpose of this study was to analyze fracture patterns and related effects of laryngeal trauma and to assess the value of 2D multiplanar reformation (MPR) and 3D reconstruction. Among 4222 consecutively registered trauma patients who underwent emergency MDCT, 38 patients had presented with laryngeal trauma. Axial, 2D MPR, 3D volume-rendered, and virtual endoscopic images were analyzed retrospectively by two blinded observers according to predefined criteria. Laryngeal fractures, soft-tissue injuries, and airway compromise were evaluated and correlated with clinical, endoscopic, surgical, and follow-up findings. Fifty-nine fractures (37 thyroid, 13 cricoid, nine arytenoid) were present in 38 patients. They were isolated in 21 (55%) patients. The other 17 (45%) patients had additional injuries to the neck, face, brain, chest, or abdomen. Laryngeal fractures were bilateral in 31 (82%) patients and were associated with hyoid bone fractures in nine (24%) patients. Arytenoid luxation was present in eight cartilages. Axial imaging missed 7 of 59 (12%) laryngeal fractures, six of eight (75%) arytenoid luxations, and four of nine (44%) hyoid bone fractures. Additional 2D MPR imaging missed 5 of 59 (8%) laryngeal fractures, five of eight (62.5%) arytenoid luxations, and two of nine (22%) hyoid bone fractures, whereas 3D volume-rendered images depicted them all. Virtual endoscopy and 3D volume rendering added diagnostic accuracy with respect to the length, width, shape, and spatial orientation of fractures in 22 of 38 (58%) patients; arytenoid luxation in six of eight (75%) luxations; and the evaluation of airway narrowing in 19 of 38 (50%) patients. Three-dimensional volume rendering was not of additional value in evaluation of the cricoid cartilage. The use of 2D MPR and 3D volume rendering with or without virtual endoscopy improved assessment of thyroid and hyoid bone fractures, arytenoid luxations, and laryngotracheal narrowing, providing helpful data for optimal management.

Extent of Arterial Tumor Enhancement Measured With Preoperative MDCT Gastrography Is a Prognostic Factor in Advanced Gastric Cancer After Curative Resection

The objective of this study was to investigate the correlation between pathologic findings and arterial tumor enhancement at MDCT gastrography of patients with a prognosis of advanced gastric cancer after curative resection. The cases of 41 patients with advanced gastric cancer (23 men, 18 women; age range, 35-92 years; median, 60 years) who underwent MDCT gastrography and optical endoscopy before surgery were retrospectively evaluated. Two radiologists reviewed virtual endoscopic and multiplanar reconstruction images to measure arterial phase CT values of the inner tumor margin and healthy gastric wall. They used consensus regions of interest on a cross-sectional image of the largest tumor diameter and then calculated tumor-to-normal wall enhancement ratio (TNR). Advanced gastric cancers were divided into high- and low-TNR groups with mean TNR as the cutoff. The correlations between groups and pathologic factors, patient survival, and mode of recurrence were studied. Multivariate logistic regression analysis showed that the arterial tumor enhancement ratio correlated with both microvessel density and lymphatic vessel invasion. The survival rate after curative resection was worse for the high-TNR group than for the low-TNR group. The rate of lymphatic and hematogenous recurrences was also higher in the high-TNR group. Multivariate survival analysis revealed that TNR was an independent prognostic factor. The extent of arterial tumor enhancement correlated with tumor angiogenesis and lymphatic vessel invasion and was a useful prognostic indicator after curative resection in patients with advanced gastric cancer.

Detection of flat colorectal polyps at screening CT colonography in comparison with conventional polypoid lesions

Although the screening of small, flat polyps is clinically important, the role of CT colonography (CTC) screening in their detection has not been thoroughly investigated. To evaluate the detection capability and usefulness of CTC in the screening of flat and polypoid lesions by comparing CTC with optic colonoscopy findings as the gold standard. We evaluated the CTC detection capability for flat colorectal polyps with a flat surface and a height not exceeding 3 mm (n = 42) by comparing to conventional polypoid lesions (n = 418) according to the polyp diameter. Four types of reconstruction images including multiplanar reconstruction, volume rendering, virtual gross pathology, and virtual endoscopic images were used for visual analysis. We compared the abilities of the four reconstructions for polyp visualization. Detection sensitivity for flat polyps was 31.3%, 44.4%, and 87.5% for lesions measuring 2-3 mm, 4-5 mm, and ≥6 mm, respectively; the corresponding sensitivity for polypoid lesions was 47.6%, 79.0%, and 91.7%. The overall sensitivity for flat lesions (47.6%) was significantly lower than polypoid lesions (64.1%). Virtual endoscopic imaging showed best visualization among the four reconstructions. Colon cancers were detected in eight patients by optic colonoscopy, and CTC detected colon cancers in all eight patients. CTC using 64-row multidetector CT is useful for colon cancer screening to detect colorectal polyps while the detection of small, flat lesions is still challenging.

P02.12: Advances in transvaginal 3D volumetric imaging: potential clinical impact of virtual ultrasound hysteroscopy

Introduction: Advances in 3D-TVS have considerably enhanced the diagnostic effectiveness of sonohysterography (SIS) technique. The introduction of “Fly Thru” (Toshiba Medical Systems) has created the concept of “ultrasound hysteroscopy”. Advanced 3D volumetric image processing of the acquired data produces greater depth perception which, together with the animated reconstruction, gives the appearance of virtual endoscopic ultrasound imaging. Aims: To review the diagnostic benefits of advanced 3D-TVS SIS and, in particular, the role of “Fly Thru” technology. Ongoing clinical trials involve SIS procedures to be carried out on 500 patients attending a leading IVF unit or established recurrent miscarriage clinic. Methods and Materials: All patients were referred to Clinical Diagnostic Services, London for SIS assessment. The SIS procedure was carried out utilising Toshiba Aplio MX and Aplio 500 (“Fly Thru”) systems. Detailed 3D-TVS imaging of the uterine cavity were obtained utilising “Fly Thru” technology in the majority of cases. Resection of “minor” intracavital lesions (e.g. polyps, adhesions etc) was carried out when deemed appropriate. Cases presenting with anatomical malformations and intracavital pathology were otherwise referred for hysteroscopic surgery. Ongoing studies. Current work strongly indicates the potential value of advanced 3D-TVS SIS and “Fly Thru” imaging. They relate to (i) increased diagnostic capability and confidence in the examination of the uterine cavity and associated abnormalities (ii) reduced need for conventional diagnostic hysteroscopy (iii) utilisation of ultrasound guided interventional techniques in selected cases. Up to date results and impressions will be outlined to include correlation between SIS ultrasound techniques and endoscopic examination as well as the impact on IVF management.