Use of the Resection Map system as guidance during hepatectomy

A Survey of Medical Visualization Through the Lens of Metaphors

We provide an overview of metaphors that were used in medical visualization and related user interfaces. Metaphors are employed to translate concepts from a source domain to a target domain. The survey is grounded in a discussion of metaphor-based design involving the identification and reflection of candidate metaphors. We consider metaphors that have a source domain in one branch of medicine, e.g., the virtual mirror that solves problems in orthopedics and laparoscopy with a mirror that resembles the dentist's mirror. Other metaphors employ the physical world as the source domain, such as crepuscular rays that inspire a solution for access planning in tumor therapy. Aviation is another source of inspiration, leading to metaphors, such as surgical cockpits, surgical control towers, and surgery navigation according to an instrument flight. This paper should raise awareness for metaphors and their potential to focus the design of computer-assisted systems on useful features and a positive user experience. Limitations and potential drawbacks of a metaphor-based user interface design for medical applications are also considered.

Comparative study on three-dimensional versus two-dimensional imaging using a computer-assisted surgery system for preoperative planning in pediatric middle hepatic tumors

BACKGROUD

The study objective was to compare three-dimensional and two-dimensional imaging using computer-assisted systems (CASs) in clinical guidance for preoperative surgical planning for middle hepatic tumors in children.

METHODS

A retrospective analysis was performed on 23 children who underwent surgery for middle hepatic tumors in our hospital from January 2016 to June 2022. The surgical resection plan was formulated by the operator team using two-dimensional CT images before the operation. Then, the same qualified surgeons conducted an in-depth analysis and formulated the surgical resection scheme for the same pediatric patient using three-dimensional imaging of the middle hepatic tumor. The feasibility of the two schemes was compared and analyzed.

RESULT

All the tumors were successfully removed according to the preoperative method developed using three-dimensional imaging. The postoperative short-term follow-up revealed that all patients were doing well. Preoperative plans were revised in 9 cases after evaluating the three-dimensional images due to the disparity between the original plans and the three-dimensional relationship between the tumor and blood vessels, vascular variation, and the volume of remnant liver.

CONCLUSIONS

Three-dimensional imaging with a computer-assisted surgery system is superior to two-dimensional imaging in the preoperative planning of pediatric hepatoblastoma.

Navigated liver surgery: State of the art and future perspectives

BACKGROUND

In recent years, the development of digital imaging technology has had a significant influence in liver surgery. The ability to obtain a 3-dimensional (3D) visualization of the liver anatomy has provided surgery with virtual reality of simulation 3D computer models, 3D printing models and more recently holograms and augmented reality (when virtual reality knowledge is superimposed onto reality). In addition, the utilization of real-time fluorescent imaging techniques based on indocyanine green (ICG) uptake allows clinicians to precisely delineate the liver anatomy and/or tumors within the parenchyma, applying the knowledge obtained preoperatively through digital imaging. The combination of both has transformed the abstract thinking until now based on 2D imaging into a 3D preoperative conception (virtual reality), enhanced with real-time visualization of the fluorescent liver structures, effectively facilitating intraoperative navigated liver surgery (augmented reality).

DATA SOURCES

A literature search was performed from inception until January 2021 in MEDLINE (PubMed), Embase, Cochrane library and database for systematic reviews (CDSR), Google Scholar, and National Institute for Health and Clinical Excellence (NICE) databases.

RESULTS

Fifty-one pertinent articles were retrieved and included. The different types of digital imaging technologies and the real-time navigated liver surgery were estimated and compared.

CONCLUSIONS

ICG fluorescent imaging techniques can contribute essentially to the real-time definition of liver segments; as a result, precise hepatic resection can be guided by the presence of fluorescence. Furthermore, 3D models can help essentially to further advancing of precision in hepatic surgery by permitting estimation of liver volume and functional liver remnant, delineation of resection lines along the liver segments and evaluation of tumor margins. In liver transplantation and especially in living donor liver transplantation (LDLT), 3D printed models of the donor's liver and models of the recipient's hilar anatomy can contribute further to improving the results. In particular, pediatric LDLT abdominal cavity models can help to manage the largest challenge of this procedure, namely large-for-size syndrome.

Integration of Three-Dimensional Liver Models in a Multimodal Image-Guided Robotic Liver Surgery Cockpit

Background: Robotic liver surgery represents the most recent evolution in the field of minimally-invasive liver surgery. For planning and guidance of liver resections, surgeons currently rely on preoperative 2-dimensional (2D) CT and/or MR imaging and intraoperative ultrasonography. Translating 2D images into digital 3-dimensional (3D) models may improve both preoperative planning and surgical guidance. The da Vinci^® robotic surgical system is a platform suitable for the integration of multiple imaging modalities into one single view. In this study, we describe multimodal imaging options and introduce the Robotic Liver Surgery Cockpit; Methods: in-house developed software was used and validated for segmentation and registration to create a virtual reality 3D model of the liver based on preoperative imaging. The accuracy of the 3D models in the clinical setting was objectively assessed in 15 patients by measuring tumor diameters and subjectively with a postoperative conducted questionnaire; Results: Implementation and applicability of the 3D model in the surgical cockpit was feasible in all patients and the quality of the 3D reconstructions was high in 14 (93%) of cases. Tumor diameters measured on CT and/or MR imaging were comparable to automated measurements using the segmentation software and 3D models; Conclusions: the 3D model was successfully incorporated in the robotic surgery console as part of a multimodality imaging platform and aided the surgeon in planning and guidance of the resection. Future studies should focus on further automation of 3D rendering and progress into augmented reality.

3D Reconstruction Methods Purporting 3D Visualization and Volume Estimation of Brain Tumors

This work proposes the Crust algorithm for 3D reconstruction of brain tumor, an effective mechanism in the visualization of tumors for presurgical planning, radiation dose calculation. Despite the promising performance of Crust algorithm in reconstruction of Stanford models, it has not yet been considered in 3D reconstruction of brain tumor. Validation of the results is done using the comparison of the 3D models from two cutting edge techniques namely the Marching Cube and the Alpha shape algorithm. The obtained result shows that Crust algorithm provides the brain tumor model with an average quality of triangle meshes ranging from 0.85 to 0.95. Concerning the visual realism, the quality of Crust algorithm models is higher on comparison to the other models. Precision of tumor volume measurement by convex hull method is analysed by repeatability and reproducibility. The standard deviations of repeatability were between 2.03 % and 3.97 %. The experimental results show that Linear Crust algorithm produces high quality meshes with average quality of equilateral triangles close to 1.

[Systematic review of current trends in preoperative planning of surgery for liver tumors]

The purpose of the study was a systematic review of current trends in preoperative planning of surgery for liver tumors. These data will be valuable to determine the advantages and disadvantages of 3D modeling, augmented reality technology and 3D printing in preoperative planning of surgery for focal liver lesions.

Preoperative 3D reconstruction images for paediatric tumours: Advantages and drawbacks

RATIONALE

Three-dimensional reconstruction (3DR) of preoperative images may improve the presurgical assessment of tumours prior to removal. We aimed to analyse the advantages and discrepancies of preoperative 3DR in paediatric tumours.

METHODS

We conducted a prospective observational study from 2016 to 2019, including patients with thoraco-abdominal tumours having predictable surgical risks on preoperative images (encasement of vessels posing vascular risks, ie, neuroblastic and soft tissue tumours or parenchyma preservation of the invaded organ, ie, liver and kidney). A comparison of 2D/3DR and surgical findings was performed.

RESULTS

Twenty-four patients, with a median age at surgery of 68.2 months (13 days-203 months), were operated on for neuroblastoma (n = 7), renal tumour (n = 7), hepatic tumour (n = 4) and others (n = 6; bone sarcoma of the iliac branch, abdominal lymph nodes of a recurrent testicular germ cell tumour, pseudoinflammatory tumour of the omentum, thoracic lipoblastoma, desmoplastic tumour, solid and pseudopapillar tumour of the pancreas). Reconstruction was of poor quality in two patients with renal tumours because computed tomography (CT) had no excretory phase. Discrepancies between 3DR and surgical findings occurred in two patients, one because of poor assessment of caliceal infiltration by renal nodules and the other because of inadequate reconstruction of renal vein thrombosis. For all the other tumours, 3DR improved the visualisation and precise location of vessels during surgery.

CONCLUSION

High-quality preoperative images are mandatory to provide the best 3DR. In the majority of cases, 3DR is of significant help during surgery to better identify vascular structures within tumours and preserve parenchyma.

Three Dimensional Reconstruction Models for Medical Modalities: A Comprehensive Investigation and Analysis

BACKGROUND

Image reconstruction is the mathematical process which converts the signals obtained from the scanning machine into an image. The reconstructed image plays a fundamental role in the planning of surgery and research in the medical field.

DISCUSSION

This paper introduces the first comprehensive survey of the literature about medical image reconstruction related to diseases, presenting a categorical study about the techniques and analyzing advantages and disadvantages of each technique. The images obtained by various imaging modalities like MRI, CT, CTA, Stereo radiography and Light field microscopy are included. A comparison on the basis of the reconstruction technique, Imaging Modality and Visualization, Disease, Metrics for 3D reconstruction accuracy, Dataset and Execution time, Evaluation of the technique is also performed.

CONCLUSION

The survey makes an assessment of the suitable reconstruction technique for an organ, draws general conclusions and discusses the future directions.

Assisting Vascular Surgery with Smartphone Augmented Reality

Background Augmented reality is a technology that expands on image-guided surgery to allow intraoperative guidance and navigation. Augmented reality-assisted surgery (ARAS) has not been implemented in the vascular field yet. The wealth of sensors found on modern smartphones make them a promising platform for implementing vascular ARAS. However, current smartphone augmented reality platforms suffer from tracking instability, making them unsuitable for precise surgery. Novel algorithms need to be developed to tackle the stability and performance limitations of mobile phone augmented reality. Aim The primary aim was to develop an ARAS system utilizing low-cost smartphone hardware for vascular surgery. The second aim was to assess its performance by evaluating the stability of its tracking algorithms. Methods We designed an ARAS system utilizing standard optical tracking (SOT) and developed a novel tracking algorithm: hybrid gyroscopic and optical tracking (HGOT) for improved tracking stability. We evaluated the stability of both tracking algorithms using a phantom model and calculated tracking errors using root mean square error (RMSE).  Results The novel augmented reality system displayed a three-dimensional (3D) guidance model fused with the patient's anatomy on a smartphone in real-time. The rotational tracking RMSE was 3.12 degrees for SOT and 0.091 degrees for HGOT. Positional tracking RMSE was 3.3 mm for SOT compared to 0.03 mm for HGOT. Comparing the stability of both tracking techniques showed HGOT to be significantly superior to SOT (p = 0.004). Conclusion We have developed a novel augmented reality system for vascular procedures. The development of HGOT has significantly increased the stability of a low-cost handheld augmented reality solution.

Use of mixed reality for improved spatial understanding of liver anatomy

Introduction: In liver surgery, medical images from pre-operative computed tomography and magnetic resonance imaging are the basis for the decision-making process. These images are used in surgery planning and guidance, especially for parenchyma-sparing hepatectomies. Though medical images are commonly visualized in two dimensions (2D), surgeons need to mentally reconstruct this information in three dimensions (3D) for a spatial understanding of the anatomy. The aim of this work is to investigate whether the use of a 3D model visualized in mixed reality with Microsoft HoloLens increases the spatial understanding of the liver, compared to the conventional way of using 2D images.Material and methods: In this study, clinicians had to identify liver segments associated to lesions.Results: Twenty-eight clinicians with varying medical experience were recruited for the study. From a total of 150 lesions, 89 were correctly assigned without significant difference between the modalities. The median time for correct identification was 23.5 [4-138] s using the magnetic resonance imaging images and 6.00 [1-35] s using HoloLens (p < 0.001).Conclusions: The use of 3D liver models in mixed reality significantly decreases the time for tasks requiring a spatial understanding of the organ. This may significantly decrease operating time and improve use of resources.

Up-to-date intraoperative computer assisted solutions for liver surgery

Computer assisted surgical planning allowed for a better selection of patients, evaluation of operative strategy, appropriate volumetric measurements, identification of anatomical risks, definition of tumour resection margins and choice of surgical approach in liver oncologic resections and living donor liver transplantations. Although preoperative computer surgical analysis has been widely used in daily clinical practice, intraoperative computer assisted solutions for risk analysis and navigation in liver surgery are not widely available or still under clinical evaluation. Computer science technology can efficiently assist modern surgeons during complex liver operations, mainly by providing image guidance with individualized 2D images and 3D models of the various anatomical and pathological structures of interest. Intraoperative computer assisted liver surgery is particularly useful in complex parenchyma-sparing hepatectomies, for intraoperative risk analysis and for the effective treatment of colorectal metastases after neoadjuvant therapy or when they are multiple. In laparoscopic liver surgery, intraoperative computer aid is definitively more important as, apart from a restricted field of view, there is also loss of the fine haptic feedback. Intraoperative computer assisted developments face challenges that prevent their application in daily clinical practice. There is a vast variety of studies regarding intraoperative computer assisted liver surgery but there are no clear objective measurements in order to compare them and select the most effective solutions. An overview of up-to-date intraoperative computer assisted solutions for liver surgery will be discussed.

Glissonian approach combined with major hepatic vein first for laparoscopic anatomic hepatectomy

BACKGROUND

Laparoscopic anatomic hepatectomy remains challenging because of the complex interior structures of the liver. Our novel strategy includes the Glissonian approach and the major hepatic vein first, which serves to define the external and internal landmarks for laparoscopic anatomic hepatectomy.

METHODS

Eleven cases underwent laparoscopic anatomic hepatectomy, including three right hepatectomies, three left hepatectomies, three right posterior hepatectomies, and two mesohepatectomies. The Glissonian approach was used to transect the hepatic pedicles as external demarcation. The major hepatic vein near the hepatic portal was exposed and served as the internal landmark for parenchymal transection. The liver parenchyma below and above the major hepatic vein was transected along the major hepatic vein. Fifty-nine subjects were used to compare the distance between the major hepatic vein and secondary Glisson pedicles among different liver diseases.

RESULTS

The average operative time was 327 min with an estimated blood loss of 554.55 mL. Only two patients received three units of packed red blood cells. The others recovered normally and were discharged on postoperative day 7. The distance between right posterior Glissonian pedicle and right hepatic vein was shorter in the patients with cirrhosis than that without cirrhosis, and this distance was even shorter in patients with hepatocellular carcinoma.

CONCLUSION

The Glissonian approach with the major hepatic vein first is easy and feasible for laparoscopic anatomic hepatectomy, especially in patients with hepatocellular carcinoma and cirrhosis.

Three-dimensional image reconstruction with free open-source OsiriX software in video-assisted thoracoscopic lobectomy and segmentectomy

OBJECTIVE

The aim of this retrospective study was to evaluate the practice and the feasibility of Osirix, a free and open-source medical imaging software, in performing accurate video-assisted thoracoscopic lobectomy and segmentectomy.

METHODS

From July 2014 to April 2016, 63 patients received anatomical video-assisted thoracoscopic surgery (VATS), either lobectomy or segmentectomy, in our department. Three-dimensional (3D) reconstruction images of 61 (96.8%) patients were preoperatively obtained with contrast-enhanced computed tomography (CT). Preoperative resection simulations were accomplished with patient-individual reconstructed 3D images. For lobectomy, pulmonary lobar veins, arteries and bronchi were identified meticulously by carefully reviewing the 3D images on the display. For segmentectomy, the intrasegmental veins in the affected segment for division and the intersegmental veins to be preserved were identified on the 3D images. Patient preoperative characteristics, surgical outcomes and postoperative data were reviewed from a prospective database.

RESULTS

The study cohort of 63 patients included 33 (52.4%) men and 30 (47.6%) women, of whom 46 (73.0%) underwent VATS lobectomy and 17 (27.0%) underwent VATS segmentectomy. There was 1 conversion from VATS lobectomy to open thoracotomy because of fibrocalcified lymph nodes. A VATS lobectomy was performed in 1 case after completing the segmentectomy because invasive adenocarcinoma was detected by intraoperative frozen-section analysis. There were no 30-day or 90-day operative mortalities CONCLUSIONS: The free, simple, and user-friendly software program Osirix can provide a 3D anatomic structure of pulmonary vessels and a clear vision into the space between the lesion and adjacent tissues, which allows surgeons to make preoperative simulations and improve the accuracy and safety of actual surgery.

Assessment of DICOM Viewers Capable of Loading Patient-specific 3D Models Obtained by Different Segmentation Platforms in the Operating Room

Patient-specific 3D models obtained by the segmentation of volumetric diagnostic images play an increasingly important role in surgical planning. Surgeons use the virtual models reconstructed through segmentation to plan challenging surgeries. Many solutions exist for the different anatomical districts and surgical interventions. The possibility to bring the 3D virtual reconstructions with native radiological images in the operating room is essential for fostering the use of intraoperative planning. To the best of our knowledge, current DICOM viewers are not able to simultaneously connect to the picture archiving and communication system (PACS) and import 3D models generated by external platforms to allow a straight integration in the operating room. A total of 26 DICOM viewers were evaluated: 22 open source and four commercial. Two DICOM viewers can connect to PACS and import segmentations achieved by other applications: Synapse 3D® by Fujifilm and OsiriX by University of Geneva. We developed a software network that converts diffuse visual tool kit (VTK) format 3D model segmentations, obtained by any software platform, to a DICOM format that can be displayed using OsiriX or Synapse 3D. Both OsiriX and Synapse 3D were suitable for our purposes and had comparable performance. Although Synapse 3D loads native images and segmentations faster, the main benefits of OsiriX are its user-friendly loading of elaborated images and it being both free of charge and open source.

Laparoscopic liver resection for posterosuperior and anterolateral lesions-a comparison experience in an Asian centre

BACKGROUND

Minimally invasive surgery has been one of the recent developments in liver surgery, laparoscopic liver resection (LLR) was initially performed for benign lesions at easily accessible locations. As the surgical techniques, technology and experience improved over the past decades, LLR surgery had evolved to tackle malignant lesions, major resections and even in difficult locations without compromising safety and principles of oncology. It was also shown to be beneficial in cirrhotic patients. We describe our initial experience with LLR in a population with significant proportion having cirrhosis, emphasising our approach for lesions in the posterosuperior (PS) segments of the liver (segments 1, 4a, 7, and 8).

METHODS

A review of patients undergoing LLR in single institution from 2006 to 2015 was performed from a prospective surgical database. Clinicopathological, operative and perioperative parameters were analyzed to compare outcomes in patients who underwent LLR for PS vs. anterolateral lesions (AL).

RESULTS

LLR was performed in consecutive 197 patients, with a mean age of 60 years. The indications for resection were hepatocellular carcinoma (HCC) (n=105; 53%), colorectal cancer liver metastasis (n=31; 16%), other malignancies (n=19; 10%) and benign lesions (n=42; 21%). A significant proportion had liver cirrhosis (25.9%). More females underwent surgery in the AL group and indications for surgery were similar between both groups. Major liver resection was performed more frequently for the PS group than for the AL group (P<0.001) and significantly more PS resections was performed in our latter experience (P=0.02). The mean operative time and the conversion rate were significantly greater in the PS group than in the AL group (P≤0.001 and 0.03, respectively). However, the estimated blood loss (EBL), rate of blood transfusion and mean postoperative stay were similar in the two groups (P=0.04, 0.88 and 0.92, respectively). The overall 90-day morbidity and mortality rate was 21.3% and 0.5% respectively, with no differences between the two groups. Surrogates of difficulty such as operative time, blood loss, conversion and outcomes e.g., morbidity and mortality, were similar in patients who underwent PS resections with or without cirrhosis.

CONCLUSIONS

LLR in selected patients is technically feasible and safe including cirrhotic patients with lesions in the PS segments.

Systematic review of the use of pre-operative simulation and navigation for hepatectomy: current status and future perspectives

Pre-operative simulation using three-dimensional (3D) reconstructions have been suggested to enhance surgical planning of hepatectomy. Evidence on its benefits for hepatectomy patients remains limited. This systematic review examined the use and impact of pre-operative simulation and intraoperative navigation on hepatectomy outcomes. A systematical searched electronic databases for studies reporting on the use and results of simulation and navigation for hepatectomy was performed. The primary outcome was change in operative plan based on simulation. Secondary outcomes included operating time (min), estimated blood loss, surgical margins, 30-day postoperative morbidity and mortality, and study-specific outcomes. From 222 citations, we included 11 studies including 497 patients. All were observational cohort studies. No study compared hepatectomy with and without simulation. All studies performed 3D reconstruction and segmentation, most commonly with volumetrics measurements. In six studies reporting intraoperative navigation, five relied on ultrasound, and one on a resection map. Of two studies reporting on it, the resection line was changed intraoperatively in one third of patients, based on simulation. Virtually predicted liver volumes (Pearson correlation r = 0.917 to 0.995) and surgical margins (r = 0.84 to 0.967) correlated highly with actual ones in eight studies. Heterogeneity of the included studies precluded meta-analysis. Pre-operative simulation seems accurate in measuring volumetrics and surgical margins. Current studies lack intraoperative transposition of simulation for direct navigation. Simulation appears useful planning of hepatectomies, but further work is warranted focusing on the development of improved tools and appraisal of their clinical impact compared to traditional resection.

Clinical efficacy of three-dimensional reconstructive technique combined with cavitron ultrasonic surgical aspirator to perform hepatectomy

AIM: To assess the clinical efficacy of three-dimensional reconstructive technique combined with cavitron ultrasonic surgical aspirator (CUSA) to perform hepatectomy.

METHODS: Fifty-three patients with pathologically confirmed hepatocellular carcinoma (HCC) who underwent hepatectomy from January 2009 to December 2012 at our hospital were divided into two groups: A and B. In group A (n = 27), hepatectomy was performed using preoperative three-dimensional reconstructive technique and CUSA during operation, while group B (n = 26) received traditional hepatectomy. Their clinical efficiency and safety were compared between the two groups.

RESULTS: The tolerance limit of hepatic inflow occlusion (the first porta hepatis) (7.4 min ± 5.6 min vs 18.3 min ± 7.6 min, P < 0.05), operative blood loss (>1 L, 18.5% vs 46.1% , P < 0.05) and blood transfusion (22.2% vs 50.0%, P < 0.05) in group A were significantly less than those in group B (P < 0.05). Moreover, cumulative survival rate showed no significant difference between the two groups (χ² = 1.165, P > 0.05). Tumor-free survival rate in group A (48.1%) was significantly higher than that in group B (30.8%) (χ² = 7.122, P < 0.05).

CONCLUSION: Hepatectomy performed using three-dimensional reconstructive technique plus CUSA is safe and effective.

Automatic evaluation of progression angle and fetal head station through intrapartum echographic monitoring

Labor progression is routinely assessed through transvaginal digital inspections, meaning that the clinical decisions taken during the most delicate phase of pregnancy are subjective and scarcely supported by technological devices. In response to such inadequacies, we combined intrapartum echographic acquisitions with advanced tracking algorithms in a new method for noninvasive, quantitative, and automatic monitoring of labor. Aim of this work is the preliminary clinical validation and accuracy evaluation of our automatic algorithm in assessing progression angle (PA) and fetal head station (FHS). A cohort of 10 parturients underwent conventional labor management, with additional translabial echographic examinations after each uterine contraction. PA and FHS were evaluated by our automatic algorithm on the acquired images. Additionally, an experienced clinical sonographer, blinded regarding the algorithm results, quantified on the same acquisitions of the two parameters through manual contouring, which were considered as the standard reference in the evaluation of automatic algorithm and routine method accuracies. The automatic algorithm (mean error ± 2SD) provided a global accuracy of 0.9 ± 4.0 mm for FHS and 4° ± 9° for PA, which is far above the diagnostic ability shown by the routine method, and therefore it resulted in a reliable method for earlier identification of abnormal labor patterns in support of clinical decisions.

Automated registration, segmentation, and measurement of metastatic melanoma tumors in serial CT scans

OBJECTIVES

Our goal was to evaluate a new software capability that integrates registration, segmentation and tumor measurement across serial exams within a picture archiving communication system (PACS) to expedite tumor measurement.

MATERIALS AND METHODS

Patients treated under institutional review board-approved protocols for metastatic melanoma were retrospectively reviewed. Of the 19 included patients, five were male, the median age was 43.2, and all received treatment using an adoptive cell therapy. Seventy-one lung, liver, and subcutaneous tumors were manually measured using RECIST (Response Evaluation Criteria In Solid Tumors) criteria before therapy (baseline computed tomography [CT]) and within 3 months after therapy (follow-up CT). We performed semiautomated registration, segmentation, and RECIST measurements at both time points within PACS (Carestream Health, Rochester, NY). We compared manual and software-generated RECIST measurements using Bland-Altman plots.

RESULTS

The median manually measured RECIST diameter for all baseline tumors was 2.1 (1.0-6.2) cm. The refined registration function identified 70/71 (98.6%) tumors on the follow-up CT. On the baseline CT, all 21 liver, 27/32 (84%) lung, and 10/18 (55%) subcutaneous tumors completed segmentation. On the follow-up CT, 19/21 (90%) liver, 21/27 (78%) lung, and 8/10 (80%) subcutaneous tumors completed segmentation. The Bland-Altman plot demonstrated a 95% confidence interval of ±0.7 cm when comparing the software-generated and manual RECIST measurements.

CONCLUSIONS

The PACS software performed semiautomated baseline tumor measurements and fully automated follow-up tumor measurements in a majority of lung, liver, and subcutaneous tumors. In our patients, semiautomated metastatic tumor measurement did not obviate the need for physician oversight due to disease and treatment-related factors.

Navigation systems in liver surgery: the new challenge for surgical research

Abstract The authors describe the theoretical basis and development of simulation systems that led to the birth of "navigation in liver surgery." Navigation is a new technological application in the surgical field that has already been successfully used in neurosurgery and orthopedic surgery. A precondition to navigate a liver resection is the availability of a map. There are three main methods to acquire images and build a three-dimensional map. Efforts to make navigation "feasible" have been made, but some limits are still affecting the method. Lack of millimetric accuracy, deformation of the liver parenchyma during resection, and breathing movements are some of the most important criticisms of this method, which, however, is still in its infancy. Not only experimental applications but also current and future foreseeable applications of such a technology are overviewed. Goals of this technology should be to reduce the intraoperative stress on surgeons, to shorten resection time, and even indirectly to enlarge resectability of patients. Further developments of this new technology applied to liver surgery could lead in the near future to safer and more precise resections, reducing the risk of postoperative liver failure, even in the presence of large anatomical alterations or, even more frequently in this surgical field, anatomical variants.

Advanced spectral analyses for real-time automatic echographic tissue-typing of simulated tumor masses at different compression stages

Prototypal software algorithms for advanced spectral analysis of echographic images were developed to perform automatic detection of simulated tumor masses at two different pathological stages. Previously published works documented the possibility of characterizing macroscopic variation of mechanical properties of tissues through elastographic techniques, using different imaging modalities, including ultrasound (US); however, the accuracy of US-based elastography remains affected by the variable manual modality of the applied compression and several attempts are under investigation to overcome this limitation. Quantitative US (QUS), such as Fourier- and wavelet-based analyses of the RF signal associated with the US images, has been developed to perform a microscopic-scale tissue-type imaging offering new solutions for operator-independent examinations. Because materials able to reproduce the harmonic behavior of human liver can be realized, in this study, tissue-mimicking structures were US imaged and the related RF signals were analyzed using wavelet transform through an in-house-developed algorithm for tissue characterization. The classification performance and reliability of the procedure were evaluated on two different tumor stiffnesses (40 and 130 kPa) and with two different applied compression levels (0 and 3.5 N). Our results demonstrated that spectral components associated with different levels of tissue stiffness within the medium exist and can be mapped onto the original US images independently of the applied compressive forces. This wavelet-based analysis was able to identify different tissue stiffness with satisfactory average sensitivity and specificity: respectively, 72.01% ± 1.70% and 81.28% ± 2.02%.

Theranostic applications: Non-ionizing cellular and molecular imaging through innovative nanosystems for early diagnosis and therapy

Modern medicine is expanding the possibilities of receiving "personalized" diagnosis and therapies, providing minimal invasiveness, technological solutions based on non-ionizing radiation, early detection of pathologies with the main objectives of being operator independent and with low cost to society. Our research activities aim to strongly contribute to these trends by improving the capabilities of current diagnostic imaging systems, which are of key importance in possibly providing both optimal diagnosis and therapies to patients. In medical diagnostics, cellular imaging aims to develop new methods and technologies for the detection of specific metabolic processes in living organisms, in order to accurately identify and discriminate normal from pathological tissues. In fact, most diseases have a "molecular basis" that detected through these new diagnostic methodologies can provide enormous benefits to medicine. Nowadays, this possibility is mainly related to the use of Positron Emission Tomography, with an exposure to ionizing radiation for patients and operators and with extremely high medical diagnostics costs. The future possible development of non-ionizing cellular imaging based on techniques such as Nuclear Magnetic Resonance or Ultrasound, would represent an important step towards modern and personalized therapies. During the last decade, the field of nanotechnology has made important progress and a wide range of organic and inorganic nanomaterials are now available with an incredible number of further combinations with other compounds for cellular targeting. The availability of these new advanced nanosystems allows new scenarios in diagnostic methodologies which are potentially capable of providing morphological and functional information together with metabolic and cellular indications.

Risk maps for liver surgery

PURPOSE

Optimal display of surgical planning data in the operating room is challenging. In liver surgery, an expressive and effective intraoperative visualization of 3D planning models is still a pressing need. The objective of this work is to visualize surgical planning information using a map display.

METHODS

An approach for risk analysis and visualization of planning models is presented which provides relevant information at a glance without the need for user interaction. Therefore, we present methods for the identification and classification of critical anatomical structures in the proximity of a preoperatively planned resection surface. Shadow-like distance indicators are introduced to encode the distance from the resection surface to these critical structures on a risk map. The work is demonstrated with examples in liver resection surgery and evaluated within two user studies.

RESULTS

The results of the performed user studies show that the proposed visualization techniques facilitate the process of risk assessment in liver resection surgery and might be a valuable extension to surgical navigations system.

CONCLUSION

The approach provides a new and objective basis for the assessment of risks during liver surgery and has the potential to improve the outcome of surgical interventions.

Theranostic applications: Non-ionizing cellular and molecular imaging through innovative nanosystems for early diagnosis and therapy

Modern medicine is expanding the possibilities of receiving “personalized” diagnosis and therapies, providing minimal invasiveness, technological solutions based on non-ionizing radiation, early detection of pathologies with the main objectives of being operator independent and with low cost to society. Our research activities aim to strongly contribute to these trends by improving the capabilities of current diagnostic imaging systems, which are of key importance in possibly providing both optimal diagnosis and therapies to patients. In medical diagnostics, cellular imaging aims to develop new methods and technologies for the detection of specific metabolic processes in living organisms, in order to accurately identify and discriminate normal from pathological tissues. In fact, most diseases have a “molecular basis” that detected through these new diagnostic methodologies can provide enormous benefits to medicine. Nowadays, this possibility is mainly related to the use of Positron Emission Tomography, with an exposure to ionizing radiation for patients and operators and with extremely high medical diagnostics costs. The future possible development of non-ionizing cellular imaging based on techniques such as Nuclear Magnetic Resonance or Ultrasound, would represent an important step towards modern and personalized therapies. During the last decade, the field of nanotechnology has made important progress and a wide range of organic and inorganic nanomaterials are now available with an incredible number of further combinations with other compounds for cellular targeting. The availability of these new advanced nanosystems allows new scenarios in diagnostic methodologies which are potentially capable of providing morphological and functional information together with metabolic and cellular indications.

Value of multidetector computed tomography image segmentation for preoperative planning in general surgery

BACKGROUND

Using practical examples, this report aims to highlight the clinical value of patient-specific three-dimensional (3D) models, obtained segmenting multidetector computed tomography (MDCT) images, for preoperative planning in general surgery.

METHODS

In this study, segmentation and 3D model generation were performed using a semiautomatic tool developed in the authors' laboratory. Their segmentation procedure is based on the neighborhood connected region-growing algorithm that, appropriately parameterized for the anatomy of interest and combined with the optimal segmentation sequence, generates good-quality 3D images coupled with facility of use. Using a touch screen monitor, manual refining can be added to segment structures unsuitable for automatic reconstruction. Three-dimensional models of 10 candidates for major general surgery procedures were presented to the operating surgeons for evaluation. A questionnaire then was administered after surgery to assess the perceived added value of the new technology.

RESULTS

The questionnaire results were very positive. The authors recorded the diffuse opinion that planning the procedure using a segmented data set allows the surgeon to plan critical interventions with better awareness of the specific patient anatomy and consequently facilitates choosing the best surgical approach.

CONCLUSIONS

The benefit shown in this report supports a wider use of segmentation software in clinical practice, even taking into account the extra time and effort required to learn and use these systems.

Comparative evaluation of laparoscopic liver resection for posterosuperior and anterolateral segments

Background

Totally laparoscopic liver resection of lesions located in the posterosuperior segments is reported to be technically challenging. This study aimed to define whether these technical difficulties affect the surgical outcome.

Methods

A total of 220 patients underwent laparoscopic liver resection during 244 procedures from August 1998 to December 2010. The patients who underwent primary minor single liver resection for malignant tumors affecting either posterosuperior segments 1, 7, 8, and, 4a (group 1) or anterolateral segments 2, 3, 5, 6, and 4b (group 2) were included in the study. Seventy-five procedures found to be eligible for the study, including 28 patients in group 1 and 47 patients in group 2. Intraoperative unfavorable incidents were graded on the basis of the Satava approach and postoperative complications were graded in agreement with the Accordion classification.

Results

The operative time (median, 127 min) and blood loss (median, 200 ml) were equivalent in the two groups. The rates for blood transfusions and intraoperative accidents did not differ statistically between the groups. A tumor-free margin resection was achieved in 94.7% of the procedures, equivalently in both groups. The postoperative course was similar in the two groups. Postoperative complications developed in 2 cases (7.1%) in group 1 and 2 cases (4.3%) in group 2 (p = 0.626). The median hospital stay was 2 days in both groups.

Conclusions

Laparoscopic liver resection for lesions located in posterosuperior segments represents certain technical challenges. However, appropriate adjustment of surgical techniques and optimal patient positioning enables the laparoscopic technique to provide safe and effective parenchyma-sparing resections for lesions located in both posterosuperior and anterolateral segments.

Laparoscopic liver surgery: new frontiers

Laparoscopic liver resection (LHR) has shown classical advantages of minimally invasive surgery over open counterpart. In spite of introduction in early 1990's only few centres worldwide adapted LHR to routine practice. It was due to considerable technical challenges and uncertainty about oncologic outcomes. Surgical instrumentation and accumulation of surgical experience has largely enabled to solve many technical considerations. Intraoperative navigation options have also been improved. Consequently indications have been drastically expanded nearly reaching criteria equal to open liver resection in expert centres. Recent studies have verified oncologic integrity of LHR. However, mastering of LHR is still a quite demanding task limiting expansion of this patient friendly technique. This emphasizes the necessity of systematic training for laparoscopic liver surgery. This article reviews the state of the art of laparoscopic liver surgery lightening burning issues of research and clinical practice.

Hepatic vessel segmentation for 3D planning of liver surgery experimental evaluation of a new fully automatic algorithm

RATIONALE AND OBJECTIVES

The aim of this study was to identify the optimal parameter configuration of a new algorithm for fully automatic segmentation of hepatic vessels, evaluating its accuracy in view of its use in a computer system for three-dimensional (3D) planning of liver surgery.

MATERIALS AND METHODS

A phantom reproduction of a human liver with vessels up to the fourth subsegment order, corresponding to a minimum diameter of 0.2 mm, was realized through stereolithography, exploiting a 3D model derived from a real human computed tomographic data set. Algorithm parameter configuration was experimentally optimized, and the maximum achievable segmentation accuracy was quantified for both single two-dimensional slices and 3D reconstruction of the vessel network, through an analytic comparison of the automatic segmentation performed on contrast-enhanced computed tomographic phantom images with actual model features.

RESULTS

The optimal algorithm configuration resulted in a vessel detection sensitivity of 100% for vessels > 1 mm in diameter, 50% in the range 0.5 to 1 mm, and 14% in the range 0.2 to 0.5 mm. An average area overlap of 94.9% was obtained between automatically and manually segmented vessel sections, with an average difference of 0.06 mm(2). The average values of corresponding false-positive and false-negative ratios were 7.7% and 2.3%, respectively.

CONCLUSIONS

A robust and accurate algorithm for automatic extraction of the hepatic vessel tree from contrast-enhanced computed tomographic volume images was proposed and experimentally assessed on a liver model, showing unprecedented sensitivity in vessel delineation. This automatic segmentation algorithm is promising for supporting liver surgery planning and for guiding intraoperative resections.

Collaborative co-design of emerging multi-technologies for surgery

The EU Research Training Network on Augmented Reality in Surgery (ARIS*ER) was established with two aims: (1) to develop next-generation novel image guidance (augmented reality based on medical images) and cross-linked robotic systems (automatic control loops guided by information sensed from the patient) and (2) to educate young researchers in the user-centred, multidisciplinary design of emerging technologies for minimally invasive surgery (MIS) and intervention radiology. Collaborations between engineers, Human Factors specialists, industrial designers and medical end users were foreseen, but actual methodologies had to be developed. Three applications were used as development vehicles and as demonstrators. The resulting teamwork and process of identifying requirements, finding solutions (in technology and workflow), and shifting between these to optimize and speed development towards quality of care were studied. The ARIS*ER approach solves current problems in collaborative teams, taking a systems approach, and manages the overview of requirements and solutions, which is too complex to manage centrally.