Magnetic resonance imaging findings of vascular malformations of the lower extremity

Vascular malformations are congenital lesions resulting from a defect during embryogenesis. Magnetic resonance imaging (MRI) is a very effective method for demonstrating detailed information regarding involved structures, extent, and flow characteristics of vascular malformations. In previous MRI studies, most of the emphasis is laid on the difference between high- and low-flow lesions, whereas little detailed information is available about the extent of local tissue involvement. These additional characteristics may influence the approach in treating these malformations and improve understanding of the pathogenesis. We retrospectively reviewed MRI scans of 40 patients with vascular malformations of the lower extremity. Thirty-four patients had low-flow lesions, and six had high-flow lesions. Of the low-flow lesions, 23 patients (67.6 percent) had muscle infiltration, with four of the six high-flow lesions having muscle infiltration. Nine of the 11 male patients (81.8 percent) with low-flow lesions had associated muscle infiltration, in comparison with 14 of the 23 female patients (60.9 percent) with low-flow lesions (p = 0.206). Eighty percent of the vascular malformations located on the thigh with muscle involvement had involvement of the anterior muscle group, whereas 86.6 percent of the patients with a vascular malformation located on the leg and with associated muscle involvement had at least the posterior muscle group involved (p = 0.0049). Ten patients (25 percent) of the whole group had bone infiltration. Low-flow lesions often had multifocal lesions (20.6 percent), whereas associated muscle atrophy was visible in 10 low-flow lesions and in two high-flow lesions. In low-flow lesions with muscle infiltration (n = 23), 43 percent (n = 10) had associated surrounding muscle atrophy (p = 0.009). Hypertrophy of the subcutaneous tissue was visible in 11 low-flow patients (32.4 percent). The high amount of muscle and bone involvement in vascular malformations of the lower extremity is emphasized with this study. Of particular interest was the difference in affected muscle groups. The angiosome concept is used to explain this preponderance, and we feel the angiosome concept could also be used when assessing possible intervention. The surrounding muscle atrophy and multifocal nature of these anomalies are further important considerations when assessing the possibility of intervention.     

VACTERL/VATER Association

Congenitally corrected transposition is a rare cardiac malformation characterized by the combination of discordant atrioventricular and ventriculo-arterial connections, usually accompanied by other cardiovascular malformations. Incidence has been reported to be around 1/33,000 live births, accounting for approximately 0.05% of congenital heart malformations. Associated malformations may include interventricular communications, obstructions of the outlet from the morphologically left ventricle, and anomalies of the tricuspid valve. The clinical picture and age of onset depend on the associated malformations, with bradycardia, a single loud second heart sound and a heart murmur being the most common manifestations. In the rare cases where there are no associated malformations, congenitally corrected transposition can lead to progressive atrioventricular valvar regurgitation and failure of the systemic ventricle. The diagnosis can also be made late in life when the patient presents with complete heart block or cardiac failure. The etiology of congenitally corrected transposition is currently unknown, and with an increase in incidence among families with previous cases of congenitally corrected transposition reported. Diagnosis can be made by fetal echocardiography, but is more commonly made postnatally with a combination of clinical signs and echocardiography. The anatomical delineation can be further assessed by magnetic resonance imaging and catheterization. The differential diagnosis is centred on the assessing if the patient is presenting with isolated malformations, or as part of a spectrum. Surgical management consists of repair of the associated malformations, or redirection of the systemic and pulmonary venous return associated with an arterial switch procedure, the so-called double switch approach. Prognosis is defined by the associated malformations, and on the timing and approach to palliative surgical care.     

Effects of magnetic resonance imaging on eye development in the C57BL/6J mouse

An investigation was undertaken to ascertain the potential teratogenicity of magnetic resonance imaging (MRI) fields. The C57BL/6J mouse was chosen as the experimental model with eye malformations (microphthalmia and morphologic anomalies) designated as the biological end point. This mouse strain is genetically predisposed to this type of malformation as a 10% spontaneous incidence occurs. Dams in groups of 15 were subjected to MRI imaging conditions on gestational day (Gd) 7 for 36 minutes to a spin-echo T-2-weighted scan by using a 1.5 Tesla magnetic field and a radiofrequency (RF) field of 64 MHz. One group was exposed at the magnetic isocenter while another was exposed at the entrance to the magnet lumen. There was also a sham control group. The dams were sacrificed at Gd 14. Assessment of eye abnormality was determined by, 1) a veterinary ophthalmologist, 2) a computer-based method comparing eye areas, and 3) a methodology combining both the above subjective and quantitative methods. MRI fields were found to produce malformation rates (15-37%) higher than controls (2-19% P less than or equal to .05, Kruskal-Wallis Test) for both isocenter and lumen entrance groups. The malformation rates and degree of statistical significance varied somewhat with analytical methodology and the unit of measure (right eye, left eye, or fetus). The results suggest for the first time the potential of MRI fields to produce developmental malformations in an animal model utilizing clinically realistic exposure conditions. (However, the reader is remained that the mouse strain utilized in this investigation was genetically prone to malformations).     

Prenatal diagnosis of vascular anomalies: update and review of the literature

Optimal care for a subgroup of infants with complicated vascular anomalies requires prenatal diagnosis. Fetal vascular lesions are either vascular tumors or vascular malformations, both of which are often detected on routine ultrasound. Imaging, such as ultrasound and fetal MRI, can be used to examine lesions and provide the data for a differential diagnosis, which may impact the course of care both in utero and postnatally. Prenatal diagnosis provides the opportunity for antenatal intervention, parental counseling, and planning of the mode and location of delivery to optimize postnatal care. Prenatal diagnosis of vascular lesions also serves to alert the physician to the potential for associated syndromes and complications. Any indication of a vascular anomaly should be referred for further examination by an experienced multidisciplinary team of physicians to ensure the window in which evaluation, planning, and treatment can take place is not missed.     

Symptomatic capillary telangiectasia of the pons and intracerebral developmental venous anomaly - A rare association

Various combinations of vascular malformations of the brain in one lesion have been reported, while others seem to be very rare. In this report, the authors discuss the case of a coexistence of an capillary telangiectasia of the pons and intracerebral venous anomaly. To our knowledge, this is the first report of coexistence of a capillary telangiectasia of the pons and intracerebral venous anomaly apparted from each other. These discrete vascular malformations of the brain raise attention on possible interrelations in the pathogenesis of these entities. We report a case of pontine capillary telangiectasia and intracerebral venous anomaly in a 42-year-old woman with a right side facial palsy. Hight field magnetic resonance imaging suggested presence of a capillary telangiectasia of the pons. Another lesion in the left frontal gyrus was attributable to the venous anomaly. Along with neuroradiological findings, results of the somatosensor evoked potentials, brain stem auditory potentials, laboratory analysis including blood, cerebrospinal fluid and urine investigation are demonstrated. Awareness of the magnetic resonance imaging finding of the capillary telangiectasias and of the venous anomalies may help in defining clinical correlates of this vascular malformations, while the follow up of these malformations might help to asses risk of vascular rupture. We and others previously selects capillary telangiectasia and venous anomaly in two discrete entities. Coexistence of these malformations in the brain apparted from each other appear to be very rare and raise attention on possible interactions in their natural history and pathogenesis.     

Combined use of digital subtraction angiography and MRI for radiosurgery and stereoencephalography

The authors report their experience with the combined use of digital subtraction angiography (DSA) and magnetic resonance imaging (MRI) for the stereotactic placement of intracerebral electrodes in epilepsy and for the radiosurgical treatment of otherwise inoperable arteriovenous malformations of the brain. Both imaging techniques, when used in conjunction, have been found most useful and complementary. For deep electrode placement, they permit optimal visualization of the cerebral structures to be reached by the electrode array while allowing the avoidance of vessels in the vicinity. For radiosurgery of arteriovenous malformations, DSA provides optimal visualization of the feeders and of the malformation itself, while the MRI reveals the cerebral structures to be spared by the photon beam of the linear accelerator. A discussion of their respective roles is presented, with the specific question as to whether MRI alone could be used for both procedures.     

The role of magnetic resonance imaging in the management of vascular malformations of the trunk and extremities

Vascular malformations can usually be diagnosed on clinical grounds. They have a well-defined appearance on magnetic resonance imaging, which can effectively determine their tissue and flow characteristics. However, the role of cross-sectional imaging in the management of vascular malformations is not well defined. Most reviews suggest that magnetic resonance imaging should be reserved for cases in which the extent of the lesion cannot be estimated on physical examination. However, to date no group has compared the accuracy of physical examination alone to that of magnetic resonance imaging in determining this extent. A review was performed of all the patients evaluated for vascular malformations at the New York University Trunk and Extremity Vascular Anomalies Conference between July of 1994 and August of 1999. Patients who underwent magnetic resonance evaluation at other institutions and whose images were not available for review were excluded. All study patients either underwent magnetic resonance imaging examination at New York University Medical Center or had outside films reviewed at the center. The physical examination findings were compared with the magnetic resonance findings and the surgeon and radiologist made a joint decision about whether there was a correlation between the magnetic resonance and physical examination findings. Fifty-eight patients met the study criteria, 44 (76 percent) of whom were found to have more extensive disease on magnetic resonance examination than appreciated on physical examination. Of the 51 patients with low-flow vascular malformations (venous vascular malformations, lymphatic malformations, and capillary malformations), 39 (76 percent) had more extensive disease on magnetic resonance examination than on physical examination. Of the seven patients with high-flow arteriovenous malformations, five had more extensive disease on magnetic resonance. In all of the 44 patients whose magnetic resonance imaging findings did not correlate with those of the physical examination, therapeutic decision making was affected. Contrary to the conventional wisdom of published reviews, physical examination findings significantly underestimated the extent of vascular malformations in the majority of cases. Magnetic resonance imaging should be performed in all patients with vascular malformations of the trunk and extremities before therapy is planned. In an age when physicians are asked to justify their decisions, especially where the use of expensive diagnostic modalities is concerned, the situations in which these tests are indispensable must be clearly defined or else patients will be denied access to them.     

Molecular pathogenesis of vascular anomalies: classification into three categories based upon clinical and biochemical characteristics

Vascular tumors and malformations can be challenging to diagnose. Although they can resemble one another, their classification into tumors, such as hemangiomas of infancy, and malformations, such as venous or arteriovenous malformations, is based not only on their divergent biological behavior, but also on their pathogenesis. This review examines the molecular pathobiology of the processes involved in the development of these vascular birthmarks as they are currently understood. The terms hemangioma, hemangiosarcoma, and vascular proliferation are often used interchangeably, even though these entities are clinically and biochemically distinct. A more precise classification is necessary to facilitate communication between basic scientists and clinicians. Vasculogenesis, the in situ differentiation of blood vessels, occurs very early in the developing embryo. In vivo and in vitro studies, as well as knockout models, seem to indicate that this mechanism is unlikely to be involved in the development of either vascular malformations or hemangiomas of infancy. Recent advances in embryonic angiogenesis, especially explorations of mechanisms of vascular remodeling, have brought new understanding of the pathogenesis of vascular malformations. Vascular remodeling, an integral part of angiogenesis that centers upon the interactions between pericytes and endothelial cells, has been shown to be defective in certain experimental models and in some familial cases of vascular malformation. The occurrences of arteriovenous malformations in territories susceptible to increased remodeling also point towards epigenetic events in the development of vascular malformations.     

Patterns of combined limb malformations.

Seven different limb malformations types were defined in 544 affected newborns, apparently free from other anomalies, obtained from a series of 297,299 livebirths. These seven malformation types were: polydactyly, limb reduction, brachydactyly, symphalangy, syndactyly and split hand/foot. One anomaly type was present in 472 newborns (1.58/1,000) and two or three in 72 (0.24/1,000). The observed combinations of two or three limb malformation types cannot be explained as chance association. Therefore, a common etiopathogenic mechanism has to be considered when two or more limb malformation types are combined in a given individual. The most frequent observed combinations were: reduction-brachydactyly, reduction-syndactyly, brachydactyly-syndactyly, polydactyly-syndactyly, and reduction-brachydactyly-syndactyly. Based on affected limb distribution, sex ratio, and familial recurrence rates, it is suggest that a reduction anomaly is the primary component in all tested combinations while syndactyly tends to be a secondary one when combined with any other limb anomaly type.     

Comparative ultrasound and magnetic resonance diagnosis of fetal CNS malformations

The study was undertaken to optimize the diagnosis of fetal CNS and facial malformations, by using a complex of ultrasound (US) and magnetic resonance imaging (MRI) studies. A hundred and forty-four fetuses with suspected CNS and facial malformations were examined. The US study conducted by a specially developed protocol was supplemented by MRI (48 fetuses) also made by a specially developed protocol. Various fetal CNS malformations, such as neural tube defects, congenital endbrain malformations, cystic lesions, tumors, ventricular complex anomalies, defects of the face and eyes, multiple defects, including CNS and facial anomalies, were detected. With MRI, the diagnosis was changed in 33% of cases. The application of a complex of US and MRI studies enhances the efficiency of diagnosis of congenital CNS and facial malformations in the fetus. MRI in the diagnosis of fetal CNS and facial malformations has a number of advantages and should be used if there is some difficulty in establishing a diagnosis when an US study is performed.     

Potentialities of magnetic resonance imaging in the complex of prenatal radiation diagnosis of fetal malformations

The purpose of the study was to investigate the potentialities of magnetic resonance imaging (MRI) in the complex of prenatal radiation diagnosis of fetal malformations. Twenty-eight female patients with suspected fetal malformations were examined. Ultrasound study was supplemented by MRI according to a specially developed protocol. Various fetal CNS malformations were diagnosed. These included the Arnold-Chiari syndrome, the Dandy-Walker syndrome, occlusive hydrocephaly, lobular holoprosencephaly, porencephaly, diaphragmatic hernias, anomalies of the abdomen and retroperitoneal space, as well as anomalies of facial structures, including median clefts, and dacryocystocele. The use of MRI in the complex prenatal radiation diagnosis makes it possible to visualize fetal malformation more clearly, contributes to the more adequate prediction of the outcome of pregnancy and to the choice of a management policy for a female patient.     

Malformations in rat fetuses induced by trypan blue

Malformations of fetuses obtained from Wistar rat dams treated with trypan blue during gestation were studied. Fetuses were examined on day 20 of gestation. One hundred and twenty-seven fetuses showed abnormalities of the external features, skeleton and internal organs, separately or in combination. External malformations were found in 108 fetuses. The most frequent external malformation was anomaly of tail. Spina bifida, club foot, exencephaly and anal atresia were also observed frequently. Skeletal malformations were detected in 48 fetuses. Deformity of vertebrae in the lumbar, sacral and/or caudal regions was found in 46 fetuses. Internal malformations were observed in 27 fetuses. Anomaly of heart and/or great vessels, hydrocephaly and micro- or anophthalmia were observed frequently. About 90% of the fetuses with skeletal malformations also showed some external malformations. In contrast, about 48% of the fetuses with internal malformations also had some external malformations. These results suggest that, for teratological study, internal examination is more important in detecting malformations of fetuses than skeletal examination.     

Dynamic bone imaging in the differential diagnosis of skeletal lesions

Dynamic bone imaging differs from routine multiphase bone scintigraphy by the use of time-activity curves (TACs) and quantitation of data. TACs were divided into an arterial plus blood pool phase (first 60 s at 1 frame/s) and a subsequent early bone uptake phase (24 min at 1 frame/min). Ratios of normalized integrals, from analogous regions were calculated to determine whether blood flow was abnormal. A key feature of the technique is the monitoring of the flow proximally and distally to the area of involvement. This was of importance in distinguishing between two diseases producing the same degree of local hyperemia.Dynamic bone imaging was applied to the differential diagnosis of arthritis, septic arthritis, cellulitis, osteomyelitis, tumor, avascular necrosis, Charcot joint, Legg-Perthes (LP) disease, and Osteochondritis Dissecans (OCD).Although the method is straightforward, there are technical and clinical factors that may affect interpretation of data. Asymmetries in flow may arise due to injection technique, interfering activity of bladder and/or bowel, vascular abnormalities, AV malformation, and venous backflow. The dynamic study is also sensitive to the effects of various modes of therapy. Consideration must be given to these technical and clinical factors for the avoidance of pitfalls in interpretation of the dynamic study.     

Embryonic and neonatal phenotyping of genetically engineered mice

Considerable progress has been made in adapting existing and developing new technologies to enable increasingly detailed phenotypic information to be obtained in embryonic and newborn mice. Sophisticated methods for imaging mouse embryos and newborns are available and include ultrasound and magnetic resonance imaging (MRI) for in vivo imaging, and MRI, vascular corrosion casts, micro-computed tomography, and optical projection tomography (OPT) for postmortem imaging. In addition, Doppler and M-mode ultrasound are useful noninvasive tools to monitor cardiac and vascular hemodynamics in vivo in embryos and newborns. The developmental stage of the animals being phenotyped is an important consideration when selecting the appropriate technique for anesthesia or euthanasia and for labeling animals in longitudinal studies. Study design also needs to control for possible differences between inter- and intralitter variability, and for possible long-term developmental effects caused by anesthesia and/or procedures. Noninvasive or minimally invasive intravenous or intracardiac injections or blood sampling, and arterial pressure and electrocardiography (ECG) measurements are feasible in newborns. Whereas microinjection techniques are available for embryos as young as 6.5 days of gestation, further advances are required to enable minimally invasive fluid or tissue samples, or blood pressure or ECG measurements, to be obtained from mouse embryos in utero. The growing repertoire of techniques available for phenotyping mouse embryos and newborns promises to accelerate knowledge gained from studies using genetically engineered mice to understand molecular regulation of morphogenesis and the etiology of congenital diseases.     

Magnetic resonance angiography in diagnosis of head and neck vessels diseases]

Aiming to study diagnostic potential of MRA 286 patients have bean observed with pathology of the brain vessels. High efficiency of MRA has been confirmed: sensitivity and specificity with vascular malformations were 98% and 96%, with arterial aneurysm it was 97% and 82%, with stenosis of more than 50% it was 98% and 46%, with stenosis of less than 50% it was 96% and 84%, with thrombosis--100% and 100%. It was noted that TOF method is the most informative nature to estimate the arterial bed. We have managed to study with the PC method venous component of malformation, residual flow in huge thrombosed aneurysm, condition of the external carotid arteries and their branches.     

Agnathia and associated malformations in a male rhesus monkey

BACKGROUND: Agnathia is a rare malformation characterized by the absence of the mandible. METHODS: A male rhesus monkey with malformations was found dead and studied by internal examination, radiographs and histopathology. RESULTS: A case of a rare first branchial arch anomaly with agenesis of the mandible and tongue is presented. The animal also had visceral deformities. However, ears were normal in shape and only slightly low in position. The craniofacial malformations may reflect incomplete separation of the first branchial arch into its maxillary and mandibular processes. CONCLUSIONS: The association between the craniofacial and other corporal anomalies is unclear.     

Compartmentalization of massive vascular malformations

A total of 18 patients with massive vascular malformations of the head and neck region were treated with compartmentalization using nonabsorbable sutures followed by injection of a sclerosant agent into each compartment. The indication for compartmentalization was either to stop potentially uncontrollable, life-threatening hemorrhage during the dissection of the lesion or to reduce its vascularity to allow a less dangerous subsequent resection. Compartmentalization was used in both high-flow and low-flow vascular malformations. In this technique, large nonabsorbable sutures are placed deeply in multiple areas within the lesion. The aim is to divide the malformation into multiple compartments by changing the direction of the suturing; in this way the sclerosing agent is provided with a more effective environment. The sclerosant used was either sodium tetradecyl sulfate 3%, absolute alcohol, or both. The total amount of infiltrate varied from 3 to 35 cc, according to the size of malformation. After compartmentalization, swelling was the most noticeable complication. With this technique, it was possible to treat what were considered untreatable malformations using standard techniques and to control the inevitable serious bleeding.     

Blood Tracer Kinetics in the Arterial Tree

Evaluation of blood supply of different organs relies on labeling blood with a suitable tracer. The tracer kinetics is linear: Tracer concentration at an observation site is a linear response to an input somewhere upstream the arterial flow. The corresponding impulse response functions are currently treated empirically without incorporating the relation to the vascular morphology of an organ. In this work we address this relation for the first time. We demonstrate that the form of the response function in the entire arterial tree is reduced to that of individual vessel segments under approximation of good blood mixing at vessel bifurcations. The resulting expression simplifies significantly when the geometric scaling of the vascular tree is taken into account. This suggests a new way to access the vascular morphology in vivo using experimentally determined response functions. However, it is an ill-posed inverse problem as demonstrated by an example using measured arterial spin labeling in large brain arteries. We further analyze transport in individual vessel segments and demonstrate that experimentally accessible tracer concentration in vessel segments depends on the measurement principle. Explicit expressions for the response functions are obtained for the major middle part of the arterial tree in which the blood flow in individual vessel segments can be treated as laminar. When applied to the analysis of regional cerebral blood flow measurements for which the necessary arterial input is evaluated in the carotid arteries, present theory predicts about 20% underestimation, which is in agreement with recent experimental data.     

Correlations between pregnancy pathology, study of the placenta, antenatal echography and examination of the product of conception in a series of 175 congenital malformations

In order to verify the hypothesis that during pregnancy in a woman without peculiar history, signs could be discovered when the fetus is malformed we have reviewed the files of 175 women who had a malformed child and of 300 controls. All of these women had at least one clinical examination and one ultrasonographic examination during pregnancy. Two clinical symptoms were more often discovered in the mother of the malformed fetus (p less than 0.001): decrease of fetal movements and small for date fetus. The placenta is never abnormal in the mother with normal fetus. Placenta is abnormal in 31% of the mother with malformed fetus but the abnormalities are not specific. Ultrasonographic examinations allowed more often the discovery of a malformation when hydramnios (p less than 0.001) or fetal hypotrophy (p less than 0.01) or an anomaly of the morphology of the fetus is discovered. Accuracy of prenatal diagnostic is considered for the different categories of congenital malformations.     

Inferior Cerebellar Hypoplasia Resembling a Dandy-Walker-Like Malformation in Purebred Eurasier Dogs with Familial Non-Progressive Ataxia: A Retrospective and Prospective Clinical Cohort Study

Cerebellar malformations can be inherited or caused by insults during cerebellar development. To date, only sporadic cases of cerebellar malformations have been reported in dogs, and the genetic background has remained obscure. Therefore, this study`s objective was to describe the clinical characteristics, imaging features and pedigree data of a familial cerebellar hypoplasia in purebred Eurasier dogs. A uniform cerebellar malformation characterized by consistent absence of the caudal portions of the cerebellar vermis and, to a lesser degree, the caudal portions of the cerebellar hemispheres in association with large retrocerebellar fluid accumulations was recognized in 14 closely related Eurasier dogs. Hydrocephalus was an additional feature in some dogs. All dogs displayed non-progressive ataxia, which had already been noted when the dogs were 5 – 6 weeks old. The severity of the ataxia varied between dogs, from mild truncal sway, subtle dysmetric gait, dysequilibrium and pelvic limb ataxia to severe cerebellar ataxia in puppies and episodic falling or rolling. Follow-up examinations in adult dogs showed improvement of the cerebellar ataxia and a still absent menace response. Epileptic seizures occurred in some dogs. The association of partial vermis agenesis with an enlarged fourth ventricle and an enlarged caudal (posterior) fossa resembled a Dandy-Walker-like malformation in some dogs. Pedigree analyses were consistent with autosomal recessive inheritance.