Biomedical subjects

S Van Sint Jan

Publications and source records attributed to S Van Sint Jan.

9 recordsLinked to original sources

PubMed2006

Multimodal visualization interface for data management, self-learning and data presentation.

A multimodal visualization software, called the Data Manager (DM), has been developed to increase interdisciplinary communication around the topic of visualization and modeling of various aspects of the human anatomy. Numerous tools used in Radiology are integrated in the interface that runs on standard personal computers. The available tools, combined to hierarchical data management and custom layouts, allow analyzing of medical imaging data using advanced features outside radiological premises (for example, for patient review, conference presentation or tutorial preparation). The system is free, and based on an open-source software development architecture, and therefore updates of the system for custom applications are possible.

Anatomy↗

PubMed2002

Registration of 6-DOFs electrogoniometry and CT medical imaging for 3D joint modeling.

The paper describes a method in which two data-collecting systems, medical imaging and electrogoniometry, are combined to allow the accurate and simultaneous modeling of both the spatial kinematics and the morphological surface of a particular joint. The joint of interest (JOI) is attached to a Plexiglas jig that includes four metallic markers defining a local reference system (R(GONIO)) for the kinematics data. Volumetric data of the JOI and the R(GONIO) markers are collected from medical imaging. The spatial location and orientation of the markers in the global reference system (R(CT)) of the medical-imaging environment are obtained by applying object-recognition and classification methods on the image dataset. Segmentation and 3D isosurfacing of the JOI are performed to produce a 3D model including two anatomical objects-the proximal and distal JOI segments. After imaging, one end of a custom-made 3D electrogoniometer is attached to the distal segment of the JOI, and the other end is placed at the R(GONIO) origin; the JOI is displaced and the spatial kinematics data is recorded by the goniometer. After recording, data registration from R(GONIO) to R(CT) occurred prior to simulation. Data analysis was performed using both joint coordinate system (JCS) and instantaneous helical axis (IHA).Finally, the 3D joint model is simulated in real time using the experimental kinematics data. The system is integrated into a computer graphics interface, allowing free manipulation of the 3D scene. The overall accuracy of the method has been validated with two other kinematics data collection methods including a 3D digitizer and interpolation of the kinematics data from discrete positions obtained from medical imaging. Validation has been performed on both superior and inferior radio-ulna joints (i.e. prono-supination motion). Maximal RMS error was 1 degrees and 1.2mm on the helical axis rotation and translation, respectively. Prono-supination of the forearm showed a total rotation of 132 degrees for 0.8mm of translation. The method reproducibility using JCS parameters was in average 1 degrees (maximal deviation=2 degrees ) for rotation, and 1mm (maximal deviation=2mm) for translation. In vitro experiments have been performed on both knee joint and ankle joint. Averaged JCS parameters for the knee were 109 degrees, 17 degrees and 4 degrees for flexion, internal rotation and abduction, respectively. Averaged maximal translation values for the knee were 12, 3 and 4mm posteriorly, medially and proximally, respectively. Averaged JCS parameters for the ankle were 43 degrees, 9 degrees and 3 degrees for plantarflexion, adduction and internal rotation, respectively. Averaged maximal translation values for the ankle were 4, 2 and 1mm anteriorly, medially and proximally, respectively.

Ankle Joint↗

PubMed1998

Effects of irradiation and methyl-triazene on craniofacial development in mouse embryos: a semiautomated morphometric analysis.

OBJECTIVE: The purpose of the present study was a 2D-semiautomated morphometric analysis of craniofacial growth in nuclear magnetic resonance imaged (NMRI) mouse embryos. METHODS: The NMRI mouse embryos were exposed in utero to either a single dose of 2 Gy X-irradiation on day 9 of gestation (113 embryos) or to 1.5 mg methyl-triazene administered orally to their pregnant mothers on gestational day 10.5 (124 embryos). An additional group of 108 embryos was used as controls. Digitized pictures of embryos from gestational days 14 to 17 were taken in lateral right view using a video system. Landmarks were located and digitized for computerized analysis of growth changes in relation to developmental stages of the face. RESULTS: The results revealed that the snout of control embryos lengthens during the developmental period considered. The snout of embryos previously submitted to methyl-triazene displayed micrognathia, and all treated fetuses exhibited macroscopic signs of microcephaly with a reduced mandible. The snouts of irradiated embryos appeared shortened at the 14-day stage and continued to shorten as development proceeded. A shortening of the midface was detected macroscopically in 83% of the cases. CONCLUSION: The results of this morphometric analysis enabled us to trace the developmental progression of the induced dysmorphosis and to assess the differences compared with normal development.

Abnormalities, Drug-Induced↗

PubMed1997

High resolution magnetic resonance imaging application in anatomy: the extensor digitorum muscle insertion on the first phalanx.

Classical dissection may give unsatisfactory results because of the presence of artifacts due to both the embalming process and displacement of the anatomical structures. This spatial disturbance could explain the divergent descriptions found in the literature about the presence, or the absence, of an insertion of the extensor digitorum muscle (ED) at the first phalanx (P1). Preliminary experiments by Van Sint Jan et al. (1996) found the same contradiction: dissections did not show a real tendon attachment, whereas a functional experiment seemed to show that "something" should exist between ED and P1 to explain the results. This paper presents the results of an in vitro MRI study of this anatomical area. A 7-T NMR microscope was used to collect accurate, noninvasive data. Subsequently, surface rendering was performed to visualize the structures in a three-dimensional manner. The results of this MRI study, together with functional data obtained in an earlier study, showed that no real insertion of ED on P1 exists. However, some collagenic fibers were occasionally-observed running from the ventral aspect of ED to both P1 and the metacarpo-phalangeal joint capsule. Those few collagenic fibers would play a secondary role in the extension of P1.

Collagen↗

PubMed1997

Joint kinematics simulation from medical imaging data.

A method for joint kinematics simulation is described. Kinematics parameters are determined from the relative displacement of marker sets placed on anatomical landmarks of surface models generated from medical imaging contour data. The landmarks are identified manually on fingers in multiple positions. A mathematical algorithm was then used to ascertain the kinematics axes of motion of the fingers. Once these axes are located, they are used as the base of a real time interactive simulation of the finger. The entire simulation was accomplished in a high-resolution graphics environment. A full complement of interactive tools (virtual dials and buttons controlled via mouse) was used to enhance the user interface. The development of the system, the model and the advantages and disadvantages of the method are discussed.

Arthrography↗

PubMed1996

The insertion of the extensor digitorum tendon on the proximal phalanx.

Review of the literature reveals that the relationship between the extensor digitorum muscle tendon to the proximal phalanx and the metacarpophalangeal joint capsule remains unclear. The present study presents data about these relationships and consists of three parts: dissection of the region, high-gradient magnetic resonance imaging, and functional study. A total of 50 hands were used. Dissection was performed on 30, magnetic resonance studies were performed on 10, and the remaining 10 hands were used for the functional analysis. Dissection did not reveal an insertion of the extensor digitorum tendon on the base of the proximal phalanx. An extension of the dorsal part of the metacarpophalangeal joint capsule running proximally toward the palmar side of the extensor tendon was observed in eight hands. In the remaining 22 hands, only loose connective tissue was found between the articular capsule and the tendon. The development of this tissue was variable. These observations were correlated using a 7T magnetic resonance installation. The results of the functional study showed that hyperextension of the proximal phalanx increased after resection of the metacarpophalangeal structures lying under the extensor tendon. In conclusion, no real tendinous insertion of the extensor digitorum tendon on the base of the proximal phalanx could be found. Loose connective tissue was observed between the metacarpophalangeal joint capsule and the palmar aspect of the tendon, which seemed to play a secondary role in the extension of the proximal phalanx.

Biomechanical Phenomena↗

PubMed1996

Comparison between two HNK-1-related antibodies immunoreactivity (HNK-1-anti-leu 7 and anti-HNK-1/N-CAM) during rat cephalogenesis.

The fixation sites of two antibodies, HNK-1-anti-leu 7 and anti- HNK-1/N-CAM, were studied during visceral cephalogenesis in the rat. The labelling patterns of both antibodies were different. Anti-leu 7 staining was restricted to trunk neural crest cells, the peripheral nervous system, myotomes and premuscular cells, the eye rudiment and the olfactory vesicle. On the other hand, anti- HNK-1/N-CAM extended to the otocyst, several epithelia (including tooth germs) and precartilages. Anti-HNK-1/N-CAM staining of somites and cranial nerve ganglia was more precocious than anti-leu 7 labelling. We conclude that both antibodies, despite several common sites labelling, display quite different immunological properties, and that the expression "HNK-1" positive has no absolute significance.

Animals↗

PubMed1994

Anatomical variations of the intrinsic muscles of the thumb.

The observation of thirty dissections of intrinsic muscles of the thumb provides some information differing from earlier anatomical studies. The abductor pollicis brevis and the opponens pollicis have been divided into muscles having six or two fascicles (or bellies), respectively. The adductor pollicis muscle has been separated into nine fascicles. Many variations were observed: absence of fascicles, presence of atrophied or supplementary fascicles, or fascicles with varying insertions sites. Neither head of the flexor pollicis brevis muscle seemed to have any fascicles. The distal insertion of its superficial head observed in this work is not in accordance with the usual description found in the literature. A new classification of the thenar muscles is presented based on the present observations. Many variations were observed: some fascicles were absent, others were supplementary or atrophied, and some had variable insertions. The importance and the individual variations of the fascicles are discussed.

Humans↗

PubMed1992

The thenar muscles. New findings.

Examination of the thenar muscles in 30 anatomical preparations of the hand have shown that the abductor pollicis brevis, the opponens pollicis, and the adductor pollicis muscles are made up of several muscle bellies. The number and insertions of these bellies are varied. Both heads of flexor pollicis brevis do not originate from any particular muscle belly. The superficial head of this muscle always inserted into the head of the thumb metacarpal, either completely, or, some of the fibres of the dorsal aponeurosis of the thumb were attached to the base of the proximal phalanx. Furthermore the anatomy of the abductor pollicis brevis muscle was related to the presence of a tendinous slip from abductor pollicis longus. These variations could have an influence on proprioception in the thumb ray.

Hand↗