Noeska N. Smit

Understanding Lymphatic Drainage Pathways of the Ovaries to Predict Sites for Sentinel Nodes in Ovarian Cancer

Objective In ovarian cancer, detection of sentinel nodes is an upcoming procedure. Perioperative determination of the patient’s sentinel node(s) might prevent a radical lymphadenectomy and associated morbidity. It is essential to understand the lymphatic drainage pathways of the ovaries, which are surprisingly up till now poorly investigated, to predict the anatomical regions where sentinel nodes can be found. We aimed to describe the lymphatic drainage pathways of the human ovaries including their compartmental fascia borders. Methods A series of 3 human female fetuses and tissues samples from 1 human cadaveric specimen were studied. Immunohistochemical analysis was performed on paraffin-embedded transverse sections (8 or 10 &mgr;m) using antibodies against Lyve-1, S100, and &agr;-smooth muscle actin to identify the lymphatic endothelium, Schwann, and smooth muscle cells, respectively. Three-dimensional reconstructions were created. Results Two major and 1 minor lymphatic drainage pathways from the ovaries were detected. One pathway drained via the proper ligament of the ovaries (ovarian ligament) toward the lymph nodes in the obturator fossa and the internal iliac artery. Another pathway drained the ovaries via the suspensory ligament (infundibulopelvic ligament) toward the para-aortic and paracaval lymph nodes. A third minor pathway drained the ovaries via the round ligament to the inguinal lymph nodes. Lymph vessels draining the fallopian tube all followed the lymphatic drainage pathways of the ovaries. Conclusions The lymphatic drainage pathways of the ovaries invariably run via the suspensory ligament (infundibulopelvic ligament) and the proper ligament of the ovaries (ovarian ligament), as well as through the round ligament of the uterus. Because ovarian cancer might spread lymphogenously via these routes, the sentinel node can be detected in the para-aortic and paracaval regions, obturator fossa and surrounding internal iliac arteries, and inguinal regions. These findings support the strategy of injecting tracers in both ovarian ligaments to identify sentinel nodes.

Lymphatic drainage pathways from the cervix uteri: Implications for radical hysterectomy?

OBJECTIVE Radical hysterectomy with pelvic lymphadenectomy is the treatment of choice for early-stage cervical cancer. Wertheims original technique has been often modified, mainly in the extent of parametrectomy. Okabayashis technique is considered as the most radical variant regarding removal of the ventral parametrium and paracolpal tissues. Surgical outcome concerning recurrence and survival is good, but morbidity is high due to autonomic nerve damage. While the autonomic network has been studied extensively, the lymphatic system is less understood. This study describes the lymphatic drainage pathways of the cervix uteri and specifically the presence of lymphatics in the vesico-uterine ligament (VUL). METHODS A developmental series of 10 human female fetal pelves was studied. Paraffin embedded blocks were sliced in transverse sections of 8 or 10 μm. Analysis was performed by staining with antibodies against LYVE-1 (lymphatic endothelium), S100 (Schwann cells), alpha-Smooth Muscle Actin (smooth muscle cells) and CD68 (macrophages). The results were three-dimensionally represented. RESULTS Two major pathways drained the cervix uteri: a supra-ureteral pathway, running in the cardinal ligament superior to the ureter, and a dorsal pathway, running in the utero-sacral ligament towards the rectal pillars. No lymph vessels draining the cervix uteri were detected in the VUL. In the paracolpal parametrium lymph vessels draining the upper vagina fused with those from the bladder. CONCLUSIONS The VUL does not contain lymphatics from the cervix uteri. Hence, the favorable survival outcomes of the Okabayashi technique cannot be explained by radical removal of lymphatic pathways in the ventrocaudal parametrium.

Toward a Highly-Detailed 3D Pelvic Model: Approaching an Ultra-Specific Level for Surgical Simulation and Anatomical Education

The surgical anatomy of the pelvis is highly complex. Anorectal and urogenital dysfunctions occur frequently after pelvic oncological surgery and are mainly caused by surgical damage of the autonomic nerves. A highly‐detailed 3D pelvic model could increase the anatomical knowledge and form a solid basis for a surgical simulation system. Currently, pelvic surgeons still rely on the preoperative interpretation of 2D diagnostic images. With a 3D simulation system, pelvic surgeons could simulate and train different scenes to enhance their preoperative knowledge and improve surgical outcome. To substantially enrich pelvic surgery and anatomical education, such a system must provide insight into the relation between the autonomic network, the lymphatic system, and endopelvic fasciae. Besides CT and MR images, Visible Human Datasets (VHDs) are widely used for 3D modeling, due to the high degree of anatomical detail represented in the cryosectional images. However, key surgical structures cannot be fully identified using VHDs and radiologic imaging techniques alone. Several unsolved anatomical problems must be elucidated as well. Therefore, adequate analysis on a microscopic level is inevitable. The development of a comprehensive anatomical atlas of the pelvis is no straightforward task. Such an endeavor involves several anatomical and technical challenges. This article surveys all existing 3D pelvic models, focusing on the level of anatomical detail. The use of VHDs in the 3D reconstruction of a highly‐detailed pelvic model and the accompanying anatomical challenges will be discussed Clin. Anat., 2013.

RegistrationShop: an interactive 3D medical volume registration system

In medical imaging, registration is used to combine images containing information from different modalities or to track treatment effects over time in individual patients. Most registration software packages do not provide an easy-to-use interface that facilitates the use of registration. 2D visualization techniques are often used for visualizing 3D datasets. RegistrationShop was developed to improve and ease the process of volume registration using 3D visualizations and intuitive interactive tools. It supports several basic visualizations of 3D volumetric data. Interactive rigid and non-rigid transformation tools can be used to manipulate the volumes and immediate visual feedback for all rigid transformation tools allows the user to examine the current result in real-time. In this context, we introduce 3D comparative visualization techniques, as well as a way of placing landmarks in 3D volumes. Finally, we evaluated our approach with domain experts, who underlined the potential and usefulness of RegistrationShop.

PelVis: Atlas-based Surgical Planning for Oncological Pelvic Surgery

Due to the intricate relationship between the pelvic organs and vital structures, such as vessels and nerves, pelvic anatomy is often considered to be complex to comprehend. In oncological pelvic surgery, a trade-off has to be made between complete tumor resection and preserving function by preventing damage to the nerves. Damage to the autonomic nerves causes undesirable post-operative side-effects such as fecal and urinal incontinence, as well as sexual dysfunction in up to 80 percent of the cases. Since these autonomic nerves are not visible in pre-operative MRI scans or during surgery, avoiding nerve damage during such a surgical procedure becomes challenging. In this work, we present visualization methods to represent context, target, and risk structures for surgical planning. We employ distance-based and occlusion management techniques in an atlas-based surgical planning tool for oncological pelvic surgery. Patient-specific pre-operative MRI scans are registered to an atlas model that includes nerve information. Through several interactive linked views, the spatial relationships and distances between the organs, tumor and risk zones are visualized to improve understanding, while avoiding occlusion. In this way, the surgeon can examine surgically relevant structures and plan the procedure before going into the operating theater, thus raising awareness of the autonomic nerve zone regions and potentially reducing post-operative complications. Furthermore, we present the results of a domain expert evaluation with surgical oncologists that demonstrates the advantages of our approach.

VarVis: visualizing anatomical variation in branching structures

Anatomical variations are naturally-occurring deviations from typical human anatomy. While these variations are considered normal and non-pathological, they are still of interest in clinical practice for medical specialists such as radiologists and transplantation surgeons. The complex variations in branching structures, for instance in arteries or nerves, are currently visualized side-by-side in illustrations or expressed using plain text in medical publications. In this work, we present a novel way of visualizing anatomical variations in complex branching structures for educational purposes: VarVis. VarVis consists of several linked views that reveal global and local similarities and differences in the variations. We propose a novel graph representation to provide an overview of the topological changes. Our solution involves a topological similarity measure, which allows the user to select variations at a global level based on their degree of similarity. After a selection is made, local topological differences can be interactively explored using illustrations and topology graphs. We also incorporate additional information regarding the probability of the various cases. Our solution has several advantages over traditional approaches, which we demonstrate in an evaluation.

Careful Dissection of the Distal Ureter Is Highly Important in Nerve-sparing Radical Pelvic Surgery: A 3D Reconstruction and Immunohistochemical Characterization of the Vesical Plexus.

Objective Radical hysterectomy with pelvic lymphadenectomy (RHL) is the preferred treatment for early-stage cervical cancer. Although oncological outcome is good with regard to recurrence and survival rates, it is well known that RHL might result in postoperative bladder impairments due to autonomic nerve disruption. The pelvic autonomic network has been extensively studied, but the anatomy of nerve fibers branching off the inferior hypogastric plexus to innervate the bladder is less known. Besides, the pathogenesis of bladder dysfunction after RHL is multifactorial but remains unclear. We studied the 3-dimensional anatomy and neuroanatomical composition of the vesical plexus and describe implications for RHL. Materials and Methods Six female adult cadaveric pelvises were macroscopically dissected. Additionally, a series of 10 female fetal pelvises (embryonic age, 10–22 weeks) was studied. Paraffin-embedded blocks were transversely sliced in 8-μm sections. (Immuno) histological analysis was performed with hematoxylin and eosin, azan, and antibodies against S-100 (Schwann cells), tyrosine hydroxylase (postganglionic sympathetic fibers), and vasoactive intestinal peptide (postganglionic parasympathetic fibers). The results were 3-dimensionally visualized. Results The vesical plexus formed a group of nerve fibers branching off the ventral part of the inferior hypogastric plexus to innervate the bladder. In all adult and fetal specimens, the vesical plexus was closely related to the distal ureter and located in both the superficial and deep layers of the vesicouterine ligament. Efferent nerve fibers belonging to the vesical plexus predominantly expressed tyrosine hydroxylase and little vasoactive intestinal peptide. Conclusions The vesical plexus is located in both layers of the vesicouterine ligament and has a very close relationship with the distal ureter. Complete mobilization of the ureter in RHL might cause bladder dysfunction due to sympathetic and parasympathetic denervation. Hence, the distal ureter should be regarded as a risk zone in which the vesical plexus can be damaged.

Illustrative multi-volume rendering for PET/CT scans

In this paper we present illustrative visualization techniques for PET/CT datasets. PET/CT scanners acquire both PET and CT image data in order to combine functional metabolic information with structural anatomical information. Current visualization techniques mainly rely on 2D image fusion techniques to convey this combined information to physicians. We introduce an illustrative 3D visualization technique, specifically designed for use with PET/CT datasets. This allows the user to easily detect foci in the PET data and to localize these regions by providing anatomical contextual information from the CT data. Furthermore, we provide transfer function specifically designed for PET data that facilitates the investigation of interesting regions. Our technique allows users to get a quick overview of regions of interest and can be used in treatment planning, doctor-patient communication and interdisciplinary communication. We conducted a qualitative evaluation with medical experts to validate the utility of our method in clinical practice.

A Unified Representation for the Model-based Visualization of Heterogeneous Anatomy Data

In the course of anatomical research, anatomists acquire and attempt to organize a great deal of heterogeneous data from different sources, such as MRI and CT data, cryosections, immunohistochemistry, manual and automatic segmentations of various structures, related literature, the relations between all of these items, and so forth. Currently, there is no way of storing, accessing and visualizing these heterogeneous datasets in an integrated fashion. Such capabilities would have great potential to empower anatomy research. In this work, we present methods for the integration of heterogeneous spatial and non-spatial data from different sources, as well as the complex relations between them, into a single model with standardized anatomical coordinates. All captured data can then be interactively visualized in various ways, depending on the anatomical question. Furthermore, our model enables data to be queried both structurally, i.e., relative to existing anatomical structures, and spatially, i.e., with anatomical coordinates. When new patient-specific medical scans are added to the model, all available model information can be mapped to them. Using this mapping, model information can be transferred back to the new scans, thus enabling the creation of visualizations enriched with information not available in the scans themselves.

An introduction to evaluation in medical visualization

Medical visualization papers often deal with data that is interpreted by medical domain experts in a research or clinical context. Since visualizations are by definition designed to be interpreted by a human observer, often an evaluation is performed to confirm the utility of a presented method. The exact type of evaluation required is not always clear, especially to new researchers. With this paper, we hope to clarify the different types of evaluation methods that exist and provide practical guidelines to choose the most suitable evaluation method to increase the value of the work.