Sectional depiction of the pelvic floor by CT, MR imaging and sheet plastination: computer-aided correlation and 3D model

Depiction of periprostatic nerve fibers by means of 1.5 T diffusion tensor imaging

PURPOSE

The knowledge of periprostatic nerve fiber (pNF) is still incomplete by means of conventional MRI. The purpose of our study was to demonstrate if DTI imaging is able to depict anatomical features of pNF.

METHODS

For this retrospective study, fifty-six patients (mean age 63.5 years), who underwent 1.5-T prostate MRI, including 32 directions DTI, were enrolled between October 2014 and December 2018. ANOVA test and Student's t-test were performed between the mean values of the number, FA values, and fiber length of pNF between base and mid-gland, mid-gland and apex, base and apex, right and left side, and anterior and posterior face of the prostate. A qualitative analysis was performed to detect the main orientation of pNF through a colorimetric 3D tractographic reconstruction.

RESULTS

The number of pNF showed a decrease from the base (322) to mid-gland (248) and apex (75) (p < 0.05). The FA values were higher at base and mid-gland (0.435 and 0.456) compared to the apex (0.313) (p < 0.05). The length of pNF was higher at apex (13.4 mm) compared to base (11.5 mm) and mid-gland (11.7 mm) (p < 0.05). The number of pNF was higher on the posterior face compared to the anterior face at base (186 vs 137), (p < 0.001). The FA values were higher on the posterior face compared to the anterior face at base (0.452 vs 0.417), mid-gland (0.483 vs 0.429), and apex (0.42 vs 0.382), (p < 0.05). The length of the pNF was higher in the posterior (14.7 mm) than in the anterior face (12 mm) at apex (p < 0.001). The main orientation of pNF was longitudinal in all patients (56/56, 100%).

CONCLUSIONS

DTI imaging has been demonstrated able to depict anatomical features of pNF.

Plastination-A scientific method for teaching and research

Over the last four decades, plastination has been one of the best processes of preservation for organic tissue. In this process, water and lipids in biological tissues are replaced by polymers (silicone, epoxy, polyester) which are hardened, resulting in dry, odourless and durable specimens. Nowadays, after more than 40 years of its development, plastination is applied in more than 400 departments of anatomy, pathology, forensic sciences and biology all over the world. The most known polymers used in plastination are silicone (S10), epoxy (E12) and polyester (P40). The key element in plastination is the impregnation stage, and therefore depending on the polymer that is used, the optical quality of specimens differs. The S10 silicone technique is the most common technique used in plastination. Specimens can be used, especially in teaching, as they are easy to handle and display a realistic topography. Plastinated silicone specimens are used for displaying whole bodies, or body parts for exhibition. Transparent tissue sections, with a thickness between 1 and 4 mm, are usually produced by using epoxy (E12) or polyester (P40) polymer. These sections can be used to study both macroscopic and microscopic structures. Compared with the usual methods of dissection or corrosion, plastinated slices have the advantage of not destroying or altering the spatial relationships of structures. Plastination can be used as a teaching and research tool. Besides the teaching and scientific sector, plastination becomes a common resource for exhibitions, as worldwide more and more exhibitions use plastinated specimens.

The utility of plastinates in court: a case of firearm homicide

Plastination is a technique renowned for its use in the preservation of human tissues or organs, and is mainly employed in anatomical training and in research regarding various scientific fields. The advantages of this method are related to the natural appearance, absence of odor, and easy-handling of the plastinated products. The use of plastinates in forensic sciences, their potential role in personal identification, and their usefulness in interpretation of post-mortem findings has been described, although literature on this topic is poor. The present paper is the first report of a firearm homicide where the brain of the victim was plastinated and presented in court as documentary evidence. Three dimensional examination of the brain during the trial allowed the judge to directly evaluate the pathway of the projectile and to compare it with the information that was presented based on depositions, post mortem data and police investigations, in a more straightforward manner. The important role played by plastination in the reported case in assisting with the final verdict could be a catalyst to extend the use of this technique to other criminal cases.

Two-dimensional sectioned images and three-dimensional surface models for learning the anatomy of the female pelvis

In the Visible Korean project, serially sectioned images of the pelvis were made from a female cadaver. Outlines of significant structures in the sectioned images were drawn and stacked to build surface models. To improve the accessibility and informational content of these data, a five-step process was designed and implemented. First, 154 pelvic structures were outlined with additional surface reconstruction to prepare the image data. Second, the sectioned and outlined images (in a browsing software) as well as the surface models (in a PDF file) were placed on the Visible Korean homepage in a readily-accessible format. Third, all image data were visualized with interactive elements to stimulate creative learning. Fourth, two-dimensional (2D) images and three-dimensional (3D) models were superimposed on one another to provide context and spatial information for students viewing these data. Fifth, images were designed such that structure names would be shown when the mouse pointer hovered over the 2D images or the 3D models. The state-of-the-art sectioned images, outlined images, and surface models, arranged and systematized as described in this study, will aid students in understanding the anatomy of female pelvis. The graphic data accompanied by corresponding magnetic resonance images and computed tomographs are expected to promote the production of 3D simulators for clinical practice.

Three-dimensional reconstruction of subject-specific knee joint using computed tomography and magnetic resonance imaging image data fusions

Three-dimensional reconstruction of human body from a living subject can be considered as the first step toward promoting virtual human project as a tool in clinical applications. This study proposes a detailed protocol for building subject-specific three-dimensional model of knee joint from a living subject. The computed tomography and magnetic resonance imaging image data of knee joint were used to reconstruct knee structures, including bones, skin, muscles, cartilages, menisci, and ligaments. They were fused to assemble the complete three-dimensional knee joint. The procedure was repeated three times with respect to three different methods of reference landmarks. The accuracy of image fusion in accordance with different landmarks was evaluated and compared with each other. The complete three-dimensional knee joint, which included 21 knee structures, was accurately developed. The choice of external or anatomical landmarks was not crucial to improve image fusion accuracy for three-dimensional reconstruction. Further work needs to be done to explore the value of the reconstructed three-dimensional knee joint for its biomechanics and kinematics.

In vivo 3D neuroanatomical evaluation of periprostatic nerve plexus with 3T-MR Diffusion Tensor Imaging

OBJECTIVES

To evaluate if Diffusion Tensor Imaging technique (DTI) can improve the visualization of periprostatic nerve fibers describing the location and distribution of entire neurovascular plexus around the prostate in patients who are candidates for prostatectomy.

MATERIALS AND METHODS

Magnetic Resonance Imaging (MRI), including a 2D T2-weighted FSE sequence in 3 planes, 3D T2-weighted and DTI using 16 gradient directions and b=0 and 1000, was performed on 36 patients. Three out of 36 patients were excluded from the analysis due to poor image quality (blurring N=2, artifact N=1). The study was approved by local ethics committee and all patients gave an informed consent. Images were evaluated by two radiologists with different experience in MRI. DTI images were analyzed qualitatively using dedicated software. Also 2D and 3D T2 images were independently considered.

RESULTS

3D-DTI allowed description of the entire plexus of the periprostatic nerve fibers in all directions, while 2D and 3D T2 morphological sequences depicted part of the fibers, in a plane by plane analysis of fiber courses. DTI demonstrated in all patients the dispersion of nerve fibers around the prostate on both sides including the significant percentage present in the anterior and anterolateral sectors.

CONCLUSIONS

DTI offers optimal representation of the widely distributed periprostatic plexus. If validated, it may help guide nerve-sparing radical prostatectomy.

Prevalence of pubovisceral muscle avulsion in a general gynecology cohort: a computed tomography (CT) study

AIMS

To calculate the prevalence of pubovisceral muscle (PM) avulsion in a cohort of women presenting at a university hospital for non-urogynecological conditions.

METHODS

Women with or without symptoms of PFD were studied in a tertiary referral urogynecology center between February and October 2010. Women were recruited from the Department of Radiology, where they were referred for a CT pelvis scan due to various pathologies. Assessment of participants included a detailed clinical interview, completion of King's Health and Prolapse-Quality of Life (P-QOL) questionnaires and spiral CT scan of the pelvis. Bilateral attachments of the PM to the pubic rami were identified in the plane of minimal hiatal dimensions, when present, and measurement of the levator symphysis gap (LSG) was taken in cases with PM complete detachment. Bivariate analysis between the PM maximum thickness and different obstetric variables was performed by using Spearman's correlation test (P < 0.05).

RESULTS

One hundred ten women were included in the analysis. The overall prevalence of PM avulsion was 6.4% (7/110). In cases with confirmed avulsion, the levator sympysis gap (LSG) ranged from 17.30 to 25.40 mm. The left PM was found to be significantly thinner in parous women and in those with a history of prolonged second stage of labor.

CONCLUSIONS

The prevalence of pubovisceral muscle avulsion using CT scanning in a general gynecology cohort is 6.4%. Thinning of the pubovisceral muscle occurs with parity and protracted labor and is more prominent on the left portion of the muscle.

Explorable three-dimensional digital model of the female pelvis, pelvic contents, and perineum for anatomical education

The anatomy of the pelvis is complex, multilayered, and its three-dimensional organization is conceptually difficult for students to grasp. The aim of this project was to create an explorable and projectable stereoscopic, three-dimensional (3D) model of the female pelvis and pelvic contents for anatomical education. The model was created using cryosection images obtained from the Visible Human Project, in conjunction with a general-purpose three-dimensional segmentation and surface-rendering program. Anatomical areas of interest were identified and labeled on consecutive images. Each 2D slice was reassembled, forming a three-dimensional model. The model includes the pelvic girdle, organs of the pelvic cavity, surrounding musculature, the perineum, neurovascular structures, and the peritoneum. Each structure can be controlled separately (e.g. added, subtracted, made transparent) to reveal organization and/or relationships between structures. The model can be manipulated and/or projected stereoscopically to visualize structures and relationships from different angles with excellent spatial perception. Because of its ease of use and versatility, we expect this model may provide a powerful teaching tool for learning in the classroom or in the laboratory.

Sonographic imaging of the puborectalis

INTRODUCTION

The aim of the present study was to compare the appearance of the normal male puborectalis using transrectal ultrasound with anatomy examinations to enhance the understanding of the relationship of the prostate to the adjacent pelvic floor. This information may help prevent damage to the puborectalis during transperineal ultrasound-guided biopsies and interventional therapies.

METHODS

Ten formalin-fixed cadavers were dissected to examine the appearance and structure of the puborectalis and its relationship with the peripheral organs. The puborectalis was also observed in a fresh male cadaver using transrectal ultrasound. In the fresh male cadaver, the puborectalis was located using transrectal sonography, the muscle was confirmed by anatomy, and the thickness was measured.

RESULTS

The ultrasonographic observations of the location of the puborectalis were confirmed by anatomy for the fresh cadaver. Bilateral, symmetrical, hypoechoic strips were observed beside the prostate in cross-section, and strip fibers were observed in the longitudinal section. The right and left puborectalis thickness measurements were 6.1 and 6.2 mm, respectively, in the sonographic image, and the measurements were 5.85 and 5.89 mm, respectively, in the formalin-fixed fresh cadaver.

CONCLUSIONS

Transrectal ultrasound provides a new imaging method to observe the male puborectalis, establishing a foundation for recognizing pelvic floor abnormalities with ultrasonography in the future.

Anatomical exploration of a dicephalous goat kid using sheet plastination (E12)

A dicephalous, 1-day-old, female goat kid was presented for anatomical study. Epoxy plastination slices (E12) were used successfully to explore this condition. They provided excellent anatomic and bone detail, demonstrating organ position, shared structures, and vascular anatomy. Sheet plastination (E12) was used as an optimal method to clarify how the two heads were united, especially the neuroanatomy. The plastinated transparent slices allowed detailed study of the anatomical structures, in a non-collapsed and non-dislocated state. Thus, we anatomically explored this rare condition without traditional dissection. The advantages of plastination extended to the preservation at room temperature of this case for further topographical investigation. To the authors' best knowledge, this is the first published report of plastination of a dicephalous goat.

Role of static and dynamic MR imaging in surgical pelvic floor dysfunction

Pelvic floor dysfunction (PFD) is a hidden women's health epidemic in the United States, with over 10% of women having a lifetime risk for undergoing a surgical repair for this problem. Given the paucity of understanding of PFD pathophysiology and the high rate of recurrence and repeat surgery, imaging plays a major role in its clinical management, especially for the preoperative assessment of patients with multicompartment defects and failed surgical repairs. The recent development of fast magnetic resonance (MR) imaging sequences allows noninvasive, radiation-free, rapid, high-resolution evaluation of the entire pelvis in one examination. The H line, M line, organ prolapse (HMO) classification system, which is applied to dynamic MR images, allows consistent standardization and grading of various forms of PFD. In addition, the HMO system clearly defines and differentiates between the two main components of PFD: pelvic floor relaxation and pelvic organ prolapse. In addition to serving as an objective diagnostic tool in patients with surgical PFD, MR imaging has tremendous potential to be used as a research tool in trying to understand the pathophysiology of these complex disorders.

The posteromedial neurovascular bundle of the ankle: an anatomic study using plastinated cross sections

PURPOSE

The aim of this study was to evaluate the topography of the posteromedial neurovascular bundle of the ankle. The anatomic relation of the posteromedial neurovascular bundle at different levels of the ankle was studied as an aid in planning minimally invasive surgery. A thorough knowledge of the local anatomy is a prerequisite before attempting release of the tibial nerve or when using the posteromedial portal for ankle arthroscopy.

METHODS

A slice anatomy study was performed on 12 intact right male cadaveric lower limbs. The distal third of each limb was cut and the foot positioned in the neutral position. The measurements were performed at the level of the tibiotalar joint, at the tip of the medial malleolus, and at the sustentaculum tali.

RESULTS

The tibial nerve is predicted to be 11.8 +/- 2.4 mm and the posterior tibial artery 16.7 +/- 3.8 mm anterior from the calcaneal tendon at the level of the tibiotalar joint. At the tip of the malleolus medialis, the tibial nerve is 14.3 +/- 2.5 mm and the posterior tibial artery 22.1 +/- 4.1 mm anterior to the Achilles tendon. The medial plantar nerve is situated at the sustentaculum tali level 8.4 +/- 3.4 mm and the lateral plantar nerve 16.1 +/- 3.1 mm posterior to the sustentaculum.

CONCLUSIONS

On the basis of our anatomic data, a posteromedial portal made at the level of the tip of the medial malleolus seems to be safe, effective, and reproducible. Therefore a portal at this level would be advantageous for an endoscopic tarsal tunnel release or when using the posteromedial portal for ankle arthroscopy. Anatomic characteristics should be kept in mind when ankle surgery is performed, thereby reducing the risk of injury to the medial neurovascular bundle and offering easy access inside the posterior compartment of the ankle.

CLINICAL RELEVANCE

This cadaveric study suggests that, by placing the posteromedial ankle portal at the tip of the medial malleolus, the risk of neurovascular injuries could be reduced.

MRI morphology of the levator ani muscle, endopelvic fascia, and urethra in women with stress urinary incontinence

OBJECTIVE

To evaluate pathomorphologic changes of the levator ani muscle, endopelvic fascia, and urethra in women with stress urinary incontinence (SUI) by MRI.

STUDY DESIGN

Fifty-four women with SUI were examined by MRI (1.5T): body phased-array coil, axial and coronal proton-density-weighted sequences.

RESULTS

The urethral sphincter muscle showed a reduced thickness of its posterior portion (37%), an omega shape (13%) or higher signal intensity (50%); its abnormal configuration was associated with an increased signal intensity in 70% (p=0.001). The levator ani muscle comprised an unilateral loss of substance in 30%, a higher signal intensity in 28%, and altered origin in 19%. Central defects of the endopelvic fascia were present in 39% (n=21), lateral defects in 46%. There was a significant association between loss of the symphyseal concavity of the anterior vaginal wall and lateral fascial defects (p=0.001) and levator ani changes (p=0.016).

CONCLUSION

MRI yields findings supporting current theories on the pathogenesis of SUI.

The sectional anatomy of the carpal tunnel and its related neurovascular structures studied by using plastination

The aim of this study was to evaluate the morphology of the carpal tunnel and its related neurovascular structures. A slice anatomy study was performed on 12 right wrists of unfixed human cadavers by using the plastination technique. The measurements were performed at the level of the pisiform, hook of the hamate and in the middle between these structures. The diameters of the carpal tunnel and the median nerve were measured at the level of the hook of the hamate. The median nerve can be predicted to be 18 +/- 1.6 mm radial to the pisiform and the ulnar neurovascular bundle 6.8 +/- 1.4 mm radial to the pisiform. Between those structures there will be at least a 9-mm area, localized 8 mm radial to the pisiform, where the incision of the transverse carpal ligament could be performed risk-free. At the hamate hook the median nerve can be predicted at 9.24 +/- 1.18 mm and the ulnar artery lies usually 1.26 +/- 2.5 mm radial to the hook. An understanding of the contents and their positions, and relationships to each other allows an accurate identification of neurovascular structures in the carpal tunnel. Our findings can be used as anatomic landmarks of the carpal tunnel and could be helpful to physicians performing carpal tunnel investigations.

Basic science and translational research in female pelvic floor disorders: proceedings of an NIH-sponsored meeting

AIMS

To report the findings of a multidisciplinary group of scientists focusing on issues in basic science and translational research related to female pelvic floor disorders, and to produce recommendations for a research agenda for investigators studying female pelvic floor disorders.

METHODS

A National Institutes of Health (NIH)-sponsored meeting was held on November 14-15, 2002, bringing together scientists in diverse fields including obstetrics, gynecology, urogynecology, urology, gastroenterology, biomechanical engineering, neuroscience, endocrinology, and molecular biology. Recent and ongoing studies were presented and discussed, key gaps in knowledge were identified, and recommendations were made for research that would have the highest impact in making advances in the field of female pelvic floor disorders.

RESULTS

The meeting included presentations and discussion on the use of animal models to better understand physiology and pathophysiology; neuromuscular injury (such as at childbirth) as a possible pathogenetic factor and mechanisms for recovery of function after injury; the use of biomechanical concepts and imaging to better understand the relationship between structure and function; and molecular and biochemical mechanisms that may underlie the development of female pelvic floor disorders.

CONCLUSIONS

While the findings of current research will help elucidate the pathophysiologic pathways leading to the development of female pelvic floor disorders, much more research is needed for full understanding that will result in better care for patients through specific rather than empiric therapy, and lead to the potential for prevention on primary and secondary levels.

Evaluation of the ankle syndesmosis: A plastination slices study

Plastination is an excellent tool for studying different anatomical and clinical questions. This technique is unique because it offers the possibility to produce transparent slices series that can be easily processed morphometrically. It is very difficult to recognize the subtle widening of the tibiofibular syndesmosis in less severe injuries of this articulation. Proper anatomic knowledge of the syndesmosis might be helpful. The ankle syndesmosis was investigated on 20 cadaver feet by using the E12 plastination technique. Each foot was cut into 1.6-mm transverse slices and then plastinated. The following parameters (reflecting the position of the fibula in the distal tibiofibular syndesmosis) were measured: the length (LFI) and the depth of the fibular incisure (DFI); the width of the clear space (TCS) and the tibiofibular overlap (TFO); the position of the fibula regarding the anterior aspect of the tibia (A); and the width of the fibula (W). Due to the unique approach of this method, values for the position of the fibular incisure with respect to the frontal (F) and sagittal (S) plane were described for the entire syndesmosis. The prevalence of syndesmotic injury in association with sprains of the ankle is up to 11%. The data presented in the study are useful for the appreciation of the correct position of the fibula in the fibular incisure and can be correlated with standard anterior-posterior radiographies and CT examinations of the ankle joint.

Magnetic resonance imaging for urinary incontinence

Magnetic resonance imaging provides the most accurate, versatile and safe imaging of the pelvic floor. Images can be produced to show sections in any plane and even in three dimensions. The resolution is such that detail as good as that seen in histological sections is possible. Once standardization of data acquisition and patient positioning is agreed we look forward to a new era of increasingly accurate diagnoses of incontinence, allowing tailored management, both surgical and nonsurgical.