Intra-operative 2D Images Research Articles

Neural patient-specific 3D-2D registration in laparoscopic liver resection.

Augmented reality guidance in laparoscopic liver resection requires the registration of a preoperative 3D model to the intraoperative 2D image. However, 3D-2D liver registration poses challenges owing to the liver's flexibility, particularly in the limited visibility conditions of laparoscopy. Although promising, the current registration methods are computationally expensive and often necessitate manual initialisation. The first neural model predicting the registration (NM) is proposed, represented as 3D model deformation coefficients, from image landmarks. The strategy consists in training a patient-specific model based on synthetic data generated automatically from the patient's preoperative model. A liver shape modelling technique, which further reduces time complexity, is also proposed. The NM method was evaluated using the target registration error measure, showing an accuracy on par with existing methods, all based on numerical optimisation. Notably, NM runs much faster, offering the possibility of achieving real-time inference, a significant step ahead in this field. The proposed method represents the first neural method for 3D-2D liver registration. Preliminary experimental findings show comparable performance to existing methods, with superior computational efficiency. These results suggest a potential to deeply impact liver registration techniques.

Possibilities and limits of intraoperative 2D imaging in trauma surgery

The two-dimensional (2D) imaging represents an essential and cost-effective component of intraoperative position control in fracture stabilization, even in the era of new three-dimensional (3D) imaging capabilities. The aim of the present study, in addition to acurrent literature review, was to examine whether the intraoperative use of 2D images leads to aquality of fracture reduction comparable to postoperative computed tomographic (CT) analysis including 3D reconstructions. Acomparative retrospective analysis of intraoperative 2D and postoperative 3D image data was performed on 21 acetabular fractures stabilized via a pararectus approach according to an established protocol using the Matta criteria. The assessment of fracture reduction in intraoperative fluoroscopy compared with postoperative CT revealed adifference only in one case with respect to the categorization of the joint step reduction in the main loading zone. In the intraoperative use of 2D imaging for fracture treatment it is important to select the correct adjustment planes taking the anatomical conditions into account in order to achieve optimum assessability. In this way, the reduction result can be adequately displayed in fluoroscopy and is also comparable to the postoperative CT control. In addition, depending on the findings, optional intraoperative dynamic fluoroscopic assessment can have adirect influence on the further surgical procedure.

A Review of 3D-2D Registration Methods and Applications based on Medical Images

The registration of preoperative three-dimensional (3D) medical images with intraoperative two-dimensional (2D) data is a key technology for image-guided radiotherapy, minimally invasive surgery, and interventional procedures. In this paper, we review 3D-2D registration methods using computed tomography (CT) and magnetic resonance imaging (MRI) as preoperative 3D images and ultrasound, X-ray, and visible light images as intraoperative 2D images. The 3D-2D registration techniques are classified into intensity-based, structure-based, and gradient-based according to the different registration features. In addition, we investigated the different application scenarios of this registration technology in medical clinical treatment, which can be divided into disease diagnosis, surgical guidance and postoperative evaluation, and also investigated the evaluation method of 3D-2D registration effect.

2D/3D Multimode Medical Image Alignment Based on Spatial Histograms

The key to image-guided surgery (IGS) technology is to find the transformation relationship between preoperative 3D images and intraoperative 2D images, namely, 2D/3D image registration. A feature-based 2D/3D medical image registration algorithm is investigated in this study. We use a two-dimensional weighted spatial histogram of gradient directions to extract statistical features, overcome the algorithm’s limitations, and expand the applicable scenarios under the premise of ensuring accuracy. The proposed algorithm was tested on CT and synthetic X-ray images, and compared with existing algorithms. The results show that the proposed algorithm can improve accuracy and efficiency, and reduce the initial value’s sensitivity.

A Randomized, Single-Blind Clinical Trial Comparing Robotic-Assisted Fluoroscopic-Guided with Ultrasound-Guided Renal Access for Percutaneous Nephrolithotomy.

We conducted a randomized, single-blind clinical trial comparing the surgical outcomes of robotic-assisted fluoroscopic-guided (RAF group) and ultrasound-guided (US group) renal access in mini-percutaneous nephrolithotomy (PCNL). We recruited patients who underwent mini-PCNL with ureteroscopic assistance for large renal stones between January 2020 and May 2021. Block randomization was performed using online software. Automated needle target with x-ray was used for fluoroscopic-guided renal access in the RAF group. PCNL was performed by residents using a pneumatic lithotripsy system with 16.5Fr/17.5Fr tracts. The primary outcome was single puncture success, and the secondary outcomes were stone-free rate, complication rate, parameters measured during renal access and fluoroscopy time. In total, 71 patients (35 in US group, 36 in RAF group) were enrolled. No difference was seen in the single puncture success rate between the US and RAF groups (34.3% and 50.0%, p=0.2). In 14.3% cases in the US group vs no cases in the RAF group, the resident was unable to obtain access due to difficult targeting (p=0.025). The mean number of needle punctures was significantly fewer, and the median duration of needle puncture was shorter in the RAF group (1.83 vs 2.51 times, p=0.025; 5.5 vs 8.0 minutes, p=0.049, respectively). The stone-free rate at 3 months after surgery was 83.3% and 70.6% in the RAF and US groups, respectively (p=0.26). Multivariate analysis revealed that RAF guidance reduced the mean number of needle punctures by 0.73 times (p=0.021). RAF renal access in mini-PCNL may have further potential applications in this field.

Global Registration of 3D Cerebral Vessels to Its 2D Projections by a New Branch-and-Bound Algorithm

Endovascular interventions are usually guided by intraoperative 2D images, which cannot fully reflect the 3D structure of vessels and sometimes cause ambiguity. Registering preoperative 3D images to intraoperative 2D images can help eliminate this ambiguity. Most existing methods can only converge to a local optimal solution. Similar to POSE [1], we formulate the problem as 2D-3D point set registration, and develop a fast and accurate global registration method. We propose a novel objective function using consensus set between the 3D points and the projection lines of the 2D points in the 3D space, and introduce a new global optimal rotation search algorithm. The translation search problem is tackled by synchronized grid search in the translation space. Furthermore, we extend the algorithm to register 3D vessels to its two projections, which only increases the runtime slightly but improves the 3D registration accuracy significantly. The proposed method is approximately two times faster than POSE. Experiments on real data show that the mean 3D rotation error is reduced from 5.55 degrees of POSE to 1.62 degrees and the mean translation error is reduced from 8.60 mm of POSE to 1.06 mm by the proposed double-plane method.

Finite-Element Based Image Registration for Endovascular Aortic Aneurysm Repair

In this paper we introduce a new method for the registration between preoperative and intraoperative computerized tomography (CT) images used in endovascular interventions for aortic aneurysm repair. The method relies on a 3D finite-element model (FEM) of the aortic centerline reconstructed from preoperative CT scans. Intraoperative 2D fluoroscopic images are used to deform the 3D FEM and align it onto the current aortic geometry. The method was evaluated on clinical datasets for which a reference CT scan was available to evaluate the registration errors made by our method and to compare them with other registration methods based on rigid transformations. Errors were estimated based on the predicted locations of landmarks positioned at different branch ostia. It appeared that our method always reduced the registration errors of at least 20% compared to gold standard 3D rigid registration and permitted to reach a global precision of 3.8 mm and a renal precision of 2.6 mm, which is a significant improvement compatible with surgical specifications. Finally, the major asset of our method is that it only requires one fluoroscopic intraoperative 2D image to perform the 3D non-rigid registration. This would reduce patient irradiation and cut the costs compared to traditional methods.

The correlation between intra-operative 2D- and 3D fluoroscopy with postoperative CT-scans in the treatment of calcaneal fractures

ObjectivesThe aim of this study was to determine the correlation of the intra-operative fluoroscopic 2D- and 3D-images compared with a postoperative CT-scan, in terms of quality of reduction and fixation of calcaneal fractures. MethodsPatients requiring open reduction and internal fixation (ORIF) of a calcaneal fracture were recruited as part of the EF3X-trial. During surgery, intra-operative images of fluoroscopic 2D- and 3D-imaging were obtained to assess the quality of the reduction and implant position. All patients received a postoperative CT-scan within one week.The operating surgeon evaluated intra-operatively both 2D- and 3D-images according to a 23-item scoring protocol on a 3-point Likert scale. A scoring panel, consisting of three clinical experts, evaluated all images in a blinded and independent fashion. Intraclass correlation coefficients (ICC) with their 95% confidence intervals (CI) were calculated using a two-way-random model with absolute agreement. ResultsA total of 102 calcaneal fractures were included. Agreement of 3D-imaging for the quality of reduction was better than 2D-imaging, although still fair, but for fixation moderate to good. Agreement between the 2D-images and the CT-scans was poor to fair. Intra-operative 2D-imaging received the highest ratings for image quality and interpretability, followed by CT-scanning. ConclusionImplant position can be evaluated satisfactory with the aid of intra-operative 3D imaging. Although intra-operative 3D imaging had a better agreement with postoperative CT-scanning than 2D-imaging, there is a need to improve image quality and suppress scattering from implants to improve the additional value of intra-operative 3D imaging in calcaneal fracture reduction and fixation.

A Comparison of Left- and Right-Sided Strain Software for the Assessment of Intraoperative Right Ventricular Function

To compare intraoperative right ventricular (RV) strain measurements made with left ventricular (LV) strain software commonly found on the echocardiography machine (Philips QLAB chamber motion quantification, version 10.7, Philips, Amsterdam, The Netherlands), with offline analysis using the dedicated RV strain software (EchoInsight, version 2.2.6.2230, Epsilon Imaging, Ann Arbor, MI). Prospective, nonrandomized, observational study. Single tertiary level, university-affiliated hospital. The study comprised 48 patients undergoing transesophageal echocardiography for cardiac or noncardiac surgery. Two-dimensional (2D) and 3-dimensional (3D) images of the right ventricle were obtained. Intraoperative 2D images were analyzed in real time for RV free wall strain (FWS) and global longitudinal strain (GLS) using QLAB chamber motion quantification (CMQ) LV strain software on the echocardiography machine. Two dimensional images were then analyzed offline to determine the RV FWS and GLS using EchoInsight RV-specific strain software. Three-dimensional images were then analyzed offline to detemine the 3D RV ejection fraction (3D RV EF) using TomTec 4D RV function (Unterschleissheim, Germany). Spearman's correlation and Bland-Altman analyses were used to characterize the relationship between RV strain measurements. Both types of strain measurements were compared to a reference standard of 3D RV EF. Intraoperative RV strain measurements using LV-specific strain software correlated with offline RV strain measurements using the RV-specific strain software (FWS rho = 0.85; GLS rho = 0.81). The bias and limits of agreement were 0.75% (- 6.66 to 8.17) for FWS and -4.53% (-11.55 to 2.50) for GLS. The sensitivity and specificity for RV dysfunction for the intraoperative LV-specific software were 94% (95% confidence interval [CI] 73-100) and 70% (95% CI 51-85), respectively, for RV FWS and 94% (95% CI 73-100) and 67% (95% CI 47-83), respectively, for RV GLS. The sensitivity and specificity for RV dysfunction for the offline RV-specific software were 89% (95% CI 65-99) and 73% (95% CI 54-88), respectively, for RV FWS and 94% (95% CI 73-100) and 30% (95% CI 15-49), respectively, for RV GLS. Intraoperative RV strain measurements using LV-specific strain software commonly available on the echocardiography machine (QLAB CMQ) correlate with offline RV strain measurements using RV-specific strain software (EchoInsight). The bias and limits of agreement for these left- and right-sided strain software suggest that these 2 measures of RV function cannot be used interchangeably. Both, however, were sensitive measures of RV dysfunction and therefore are likely clinically relevant.

A real-time and registration-free framework for dynamic shape instantiation.

Real-time 3D navigation during minimally invasive procedures is an essential yet challenging task, especially when considerable tissue motion is involved. To balance image acquisition speed and resolution, only 2D images or low-resolution 3D volumes can be used clinically. In this paper, a real-time and registration-free framework for dynamic shape instantiation, generalizable to multiple anatomical applications, is proposed to instantiate high-resolution 3D shapes of an organ from a single 2D image intra-operatively. Firstly, an approximate optimal scan plane was determined by analyzing the pre-operative 3D statistical shape model (SSM) of the anatomy with sparse principal component analysis (SPCA) and considering practical constraints. Secondly, kernel partial least squares regression (KPLSR) was used to learn the relationship between the pre-operative 3D SSM and a synchronized 2D SSM constructed from 2D images obtained at the approximate optimal scan plane. Finally, the derived relationship was applied to the new intra-operative 2D image obtained at the same scan plane to predict the high-resolution 3D shape intra-operatively. A major feature of the proposed framework is that no extra registration between the pre-operative 3D SSM and the synchronized 2D SSM is required. Detailed validation was performed on studies including the liver and right ventricle (RV) of the heart. The derived results (mean accuracy of 2.19mm on patients and computation speed of 1ms) demonstrate its potential clinical value for real-time, high-resolution, dynamic and 3D interventional guidance.

Intraoperative 3D imaging in the treatment of elbow fractures--a retrospective analysis of indications, intraoperative revision rates, and implications in 36 cases.

BackgroundThree-dimensional (3D) imaging with a mobile C-arm has proven to be a valuable intraoperative tool in trauma surgery. However, little data is available concerning its use in the treatment of elbow fractures. The aim of the current study was to determine the intraoperative findings and consequences of 3D imaging in the treatment of elbow fractures.MethodsBetween 2001 and 2015, prospectively collected data of 36 patients who underwent intraoperative 3D imaging during elbow surgery were recorded. The findings and consequences of the intraoperative 3D scans were analyzed in a retrospective chart review. For clinical evaluation the analysis included the patients’ medical history, the injury pattern of the affected elbow and concomitant injuries. Intraoperative and postoperative complications and revision surgeries were evaluated as well.ResultsIn 6 patients (16.7 %) analysis of the intraoperative 3D scan led to an immediate revision due to the detection of intra-articular screw placement (n = 3, 8.3 %) and remaining intra-articular step of >2 mm (n = 3, 8.3 %). In all of these patients, correct implant positioning and anatomical reduction could be achieved after immediate intraoperative revision, which was verified by a repeated intraoperative 3D scan. None of the 36 patients needed surgical revision based on postoperative radiological examinations due to secondary dislocation, wrong implant placement or remaining steps in the articular surface.ConclusionsIntraoperative 3D imaging offers additional information about fracture reduction and implant positioning in the treatment of elbow fractures compared to conventional intraoperative 2D imaging. It may therefore reduce the need for revision surgery. The value of intraoperative 3D imaging for clinical outcomes still needs to be assessed.

Does intraoperative fluoroscopic 3D imaging provide extra information for fracture surgery?

Fracture surgery of the extremities using 2D fluoroscopy frequently fails to detect the suboptimal positioning of implants and joint incongruities. The use of intraoperative 3D-rotational X-ray (3D-RX) imaging with a new X-ray device potentially reveals these failures. We compared 50 intraoperative (2D) results of surgery and certainty about the effectiveness of different aspects of fracture reduction as interpreted from conventional (2D) methods versus intraoperative 3D-RX in 42 distal extremity fractures by means of a surgery questionnaire. In addition, we investigated the need for revision surgery based on postoperative radiological findings in 81 patients. After fracture reduction, just before a 3D-RX scan, the surgeon preoperatively assessed the result of surgery. Three months after surgery, the 3D-RX scan was judged by three experienced surgeons independently. Intraoperative 3D-RX showed significantly more information as to screw positioning and rotation of the fracture reduction than the conventional method (p < 0.005). None of the 81 patients in whom 3D-RX was performed needed surgical revision based on postoperative radiological examinations. Intraoperative 3D-RX with this new device scanning offers additional information about extremity fracture reduction as compared to conventional intraoperative 2D imaging, and may reduce the need for revision surgery. The value of 3D-RX on functional outcomes still needs to be assessed.