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Computed tomography, magnetic resonance MR imaging, and MR angiography allowed study of the degree of duplicative changes in diprosopus, especially for planning cosmetic correction. Anomalous vessel in the middle ear: An 8-year-old child was examined because of conductive hearing loss with a retrotympanic mass on otoscopy. CT and MR angiography showed a large inferior tympanic artery traversing the hypotympanum and joining a thin, irregular internal carotid artery with a normal middle meningeal artery.
These investigations, coupled with knowledge of the embryological development allowed a diagnosis of a complex vascular anomaly in the middle ear and avoided potential surgical complications. Gadolinium-enhanced three-dimensional 3D MR angiography is a useful imaging technique for patients with congenital heart disease. This study sought to determine the added value of creating 3D shaded surface displays compared to standard maximal intensity projection MIP and multiplanar reformatting MPR techniques when analyzing 3D MR angiography data. Seventeen patients range, 3 months to 51 years old with a variety of congenital cardiovascular defects underwent gadolinium-enhanced 3D MR angiography of the thorax.
Color-coded 3D shaded surface models were rendered from the image data using manual segmentation and computer-based algorithms. Models could be rotated, translocated, or zoomed interactively by the viewer. No additional diagnostic information was gained from 3D model analysis. Qualitatively, the 3D models were more easily interpreted and enabled adjacent vessels to be distinguished more readily.
Routine use of 3D shaded surface reconstructions for visualization of contrast enhanced MR angiography in congenital heart disease cannot be recommended. Inflammatory aortic arch syndrome: To determine the value of contrast-enhanced, three-dimensional MR angiography for the evaluation of stenotic and occlusive vascular lesions in inflammatory aortic arch syndrome. In a total of examined vascular territories, DSA revealed 50 stenoses and 35 occlusions.
All lesions were detected by MRA.
In 23 segments, the degree of stenosis was overestimated by MRA. Despite a tendency to overestimate stenoses, contrast-enhanced three-dimensional MR angiography is a valid, non-invasive technique in the assessment of inflammatory aortic arch syndrome. Gadolinium-enhanced MR angiography of arterial occlusive disease in lower extremity: To compare the diagnostic value of gadolinium-enhanced MR angiography with that of conventional digital subtraction angiography for the evaluation of lower extremity arterial occlusive diseases.
In 26 patients with symptomatic lower extremity arterial occlusive disease, both conventional digital subtraction angiography DSA and gadolinium-enhanced MR angiography CE-MRA were performed during the same week. MR angiography was performed using three-dimensional gradient-echo acquisition before, and two sequential acquisitions after, the administration of gadolinium 0. In 23 patients, two separate, contiguous areas were scanned using additional doses. In three patients, only one field with a suspicious lesion was scanned. From among a total of segments, DSA detected 99 which were significantly narrowed stenosis, 33; occlusion, Using MR angiography , segments stenosis 39; occlusion, 63 were identified, and 94 lesions stenosis, 32; occlusion, 62 were graded correctly.
Seven lesions were overestimated and four were underestimated. To prove the absence of lesions, we repeated DSA in two patients with arterial spasm due to puncture. Three occluded segments seen on DSA, which revealed intact segments on MR angiography , suggested slow distal flow after reconstitution.
For the evaluation of lower extremity arterial occlusive disease, the diagnostic value of gadolinium-enhanced MR angiography is comparable with that of digital subtraction angiography. The advantages of the. Three-dimensional black blood MR angiography of the liver during breath holding. A comparison with two-dimensional time-of-flight MR angiography. Therefore, a 3-D black blood MRA of the liver was attempted in 7 healthy volunteers, using a 3-D gradient echo sequence which allows imaging during breath holding.
In all subjects, 3-D MRA allowed visualization of the trunk, 1st-, and 2nd-order branches of the portal vein without interruption. However, with 2-D MRA, the transverse portion of the left main portal vein could not be visualized in any subject, and the periphery of the portal vein was less clear than with 3-D MRA. Evaluation of the pedal artery: To compare the three-dimensional gadolinium-enhanced MR angiography with digital subtraction angiography DSA for evaluation of the pedal artery.
Among ten of the 11 patients, the following conditions were present: The remaining patient underwent angiography prior to flap surgery. For MR angiography , a 1. A three-dimensional FISP fast imaging with steady state precession sequence was obtained before enhancement, followed by four sequential acquisitions scan time, 20 secs, scan interval time, 10 secs 10 seconds after intravenous bolus injection of normal saline total 10 cc , following intravenous administration of gadolinium 0.
Arterial segments of the ankle and foot were classified as the anterior or posterior tibial artery, the distal peroneal artery, the medial or lateral plantar artery, the pedal arch, and the dorsalis pedis artery. Two radiologists independently analysed visualization of each arteraial segment and the mean of visible arterial segments in one extreminty using CE- MR angiography and DSA.
Comparison with conventional coronary angiography in ten cases. To assess the diagnostic value of two-dimensional coronary magnetic resonance MR angiography in patients evaluated for ischemic heart disease. Ten patients who underwent selective cardiac catheterization with coronary MR angiography were evaluated with two-dimensional coronary MR angiography.
The left main coronary artery, proximal left anterior descending artery, circumflex artery and right coronary artery were demonstrated in all cases. Continuous segments mean of left anterior descending, circumflex and right coronary arteries visualized on MRA were 6. Breath-hold two-dimensional coronary MR angiography was useful in showing relatively long segments of the main coronary arteries and also has potential in depicting hemodynamically significant coronary artery lesions.
A simulation study of enhancement duration in three-dimensional contrast-enhanced MR angiography. In our study on three-dimensional 3D contrast-enhanced MR angiography we performed a computer simulation to investigate quantitative vessel visibility. In the simulation, we evaluated the relative loss of signal intensity in a vessel due to shortened duration of contrast-enhancement. The mid-point of enhancement-duration was assumed to be at the point in which the data in the center of k-space k y axis was acquired.
Signal intensity of a vessel decreased as the enhancement-duration was shortened and the diameter of the vessel was decreased. This suggests that the vessel visibility is high. At anytime during data acquisition, we could set the phantom on the region being scanned or take it out by using the ''pause'' function of the MR scanner. This made it possible to change the enhancement-duration to match the simulation.
Results of the phantom study were comparable to those of the simulation, suggesting that the simulation was valid. Our results and simple techniques for both the simulation and the phantom study using the ''pause'' function, were considered useful in the study of 3D MR angiography. Hemodynamics of ovarian veins: MR angiography in women with uterine leiomyomata. The passive reflux into ovarian veins OVs is well known as a common finding in normal asymptomatic women. The purpose of this study was to investigate the hemodynamics of OVs in women with myomatous uterus.
The frequency of reflux into OVs on TOF- MR angiography was retrospectively assessed with uterine volume, and compared to that of normal women in previous publication. The statistical evaluation was performed using Fisher's exact test. These rates were significantly lower than those of normal asyptomatic women in the previous publication p MR angiography. These findings suggested myomatous uterus could affect the flow direction of OVs, and passive reflux into OVs might be prevented due to the influence of antegrade flow of OVs.
Non-contrast MR angiography for diagnosis of congenital heart disease. Fast imaging employing steady state acquisition FIESTA has been reported to be suitable for cardiac imaging in adolescents and adults. The measurements of the vascular diameters and diagnostic quality of the two techniques were compared. The agreement of the vascular diameters in the Bland-Altman method was good aAo 0.
Due to signal loss caused at the regions of vascular stenosis or Blalock-Taussig shunt on FIESTA, we could not evaluate the vascular diameter or patency at those lesions. Peripheral neuropathy due to vasculitis without any complications of vasculitis in other organs was first reported in This condition was termed non-systemic vasculitic neuropathy NSVN.
Although vasculitis is believed to develop in small arteries and arterioles in this disease, the level of vascular involvement has not been fully established. We present a case of NSVN followed up by MR angiography , which was thought to be useful to assess the level as well as the state of vascular lesions in this condition. High-resolution coronary MR angiography for evaluation of patients with anomalous coronary arteries: Anomalous origin of the coronary artery from the contralateral coronary sinus is a rare coronary anomaly associated with sudden death.
The inter-arterial course is most closely associated with sudden death, but it has been suggested that the presence of an intramural segment of a right anomalous coronary is associated with more symptoms and therefore may be an important criterion for intervention in these patients. To demonstrate that MR angiography can accurately determine the presence or absence of an intramural segment in an anomalous coronary artery. All studies of children who underwent MR angiography for the evaluation of an anomalous coronary artery were retrospectively reviewed by two pediatric radiologists in consensus.
Criteria for an intramural anomalous coronary artery were the presence of a small or slit-like ostium and the relative smaller size of the proximal intramural portion of the coronary artery in relation to the more distal epicardial coronary artery. The anomalous coronary artery was classified as not intramural if these two findings were absent. These findings were correlated with operative reports confirming the presence or absence of an intramural segment. MR angiography may be able to reliably identify the intramural segment of an anomalous coronary artery in older children using the imaging criteria of a small or slit-like ostium and relative decrease in size of the proximal portion of the anomalous coronary artery compared to the distal portion of the anomalous coronary artery.
Determining the presence of the intramural segment may help with surgical planning and may be an important. Time-resolved MR angiography of the renal artery: To prove the hypothesis that renal artery stenosis and changes in renal perfusion can be detected with contrast-enhanced time-resolved MR angiography in a single examination. In 71 patients, renal arteries and 14 accessory renal arteries were studied. The examinations were performed on a 1.
A T 1 -weighted gradient echo sequence with a temporal resolution of 7 s was used. Single dose of contrast material 0. Criterion for the assessment of renal perfusion was the slope ratio of the signal intensity time curve in both kidneys. Forty renal artery stenoses and one occlusion of a renal artery were detected. The accuracy of the slope ratio limit value 0. Time-resolved MR angiography can detect changes in renal perfusion in patients with unilateral renal artery stenosis. Carotid-anterior cerebral artery anastomosis on MR angiography: Rarely in the anterior circulation, an anastomosis of the carotid and anterior cerebral arteries occurs when an anomalous branch arises from the ophthalmic segment of the internal carotid artery and anastomoses with the A1-A2 junction of the anterior communicating artery.
Right-side predominance is known. To our knowledge, the incidence of carotid-anterior cerebral artery anastomosis has not been reported, so we researched cases in our institution records to determine incidence and investigated characteristic features of the condition on magnetic resonance MR angiography. To isolate such cases, we retrospectively reviewed cranial MR angiographic images of 3, consecutive patients in our institution. We found three cases with carotid-anterior cerebral artery anastomosis two men, one woman , representing an incidence of 0.
The anastomosis was on the right in all three cases. A normal A1 segment of the anterior cerebral artery ACA was present in two cases but could not be identified in the remaining case on MR angiographic images that included source images. Two of the three patients demonstrated associated arterial variations in their carotid systems. On MR angiography , we observed a 0. We found a high frequency of other associated arterial variations in the carotid system. Diagnosis of the hypothenar hammer syndrome by high-resolution contrast-enhanced MR angiography.
Our objective was to describe the imaging features of hypothenar hammer syndrome using minimally invasive contrast-enhanced MR angiography in comparison with oscillography study. In five patients with hypothenar hammer syndrome Gd-BOPTA-enhanced elliptically reordered 3D pulse sequence MR was compared with oscillography findings and clinical symptoms focusing on angiographic appearance of vessel injury, distribution pattern of hand vasculature and joining branches between the radial and ulnar artery supply.
All patients showed segmental occlusion at the site of trauma impact with varying involvement of the superficial palmar arch, common volar digital arteries. Good correspondence was found between angiographic appearance including the presence of collaterals, clinical symptoms and oscillography. Bilateral comparison was helpful in distinguishing between vessel variants and pathology. Bilateral Gd-BOPTA-enhanced MR angiography is a minimally invasive method to depict clearly the localization and extent of vessel injury in hypothenar hammer syndrome providing valuable information about distribution pattern of hand vasculature and presence of collaterals; however, no flow data can be obtained.
Enhanced MR angiography of the lower extremities with synergy spine coil. A synergy spine coil is a phased-array coil designed for spine imaging. The coil's sensitive area is narrow in both the x-axis and y-axis directions but very wide in the z-axis direction. It is therefore suitable for using in long parts of the body, such as the spine. We used the coil for enhanced MR angiography in the lower extremities, which requires a very long field of view on the z-axis direction.
Using on the NEMA National Electrical Manufacturers Association standard test for special-purpose coils, the sensitive volume of the synergy spine coil was first measured by using a phantom. It was found that the sensitive lengths along x-axis and y-axis were mm and mm, respectively, while that along z-axis could set at any length required for the examination by modifying the element number.
The above area was confirmed to be sufficient for obtaining enhanced MR angiograms of the lower extremities. The results of this study showed the use of the synergy spine coil in enhanced MR angiography of the lower extremities is superior to the use of a conventional whole body coil for obtaining good MR angiograms with a good single-to-noise ratio SNR. MR angiography of eddy-current-free MR imaging system with a 3T permanent magnet.
This paper reports that, the authors main purpose was to evaluate two-dimensional time flight MR angiography in the visualization of vascular structure by using an eddy-current-free 0. The authors have developed multisection acquisition technique for two-dimensional time-of-flight MR angiography with the use of velocity-compensated gradient echoes.
MR angiograms were obtained with a ray-tracing algorithm of the new modified maximum intensity projection at various viewing angles. These angiograms are displayed on cathode-ray tubes in a high-speed cyclic mode to depict the front-rear relation of vessels for better recognition. With an eddy-current-free permanent magnet system, two-dimensional time-of-flight angiography could clearly depict intracranial vascular structure, cervical vessels, and vessels of the extremities with thin-section 2 or 3 mm acquisition.
A high flip angle 90 degrees with a short TR enabled better differentiation between blood flow and stationary tissues. Stenosis of the carotids could be detected in accordance with digital subtraction angiography. MR imaging and MR angiography in preoperative evaluation of intracranial meningiomas. Use of MRA was also helpful in demonstrating the degree of intrinsic tumor vascularity. It also supplied important information for operative planning.
Adjunct XRA was mandatory if detailed information about tumor-feeding vessels was requested by the neurosurgeon, especially in highly vascularized angiomatous meningiomas and in meningiomas suspected of tumor feeding by vessels of the internal carotid artery. A short-duration CHESS pulse causes broad frequency band saturation, creating extensive offset from the resonance frequency of water. Dynamic contrast-enhanced subtraction MR angiography in intracranial vascular abnormalities. We present our clinical experience with dynamic contrast-enhanced MR angiography MRA with subtraction for assessing intracranial vascular abnormalities.
Ten patients with various cerebrovascular disorders underwent dynamic contrast-enhanced MRA on a 1. Thirty sections 2 mm were acquired in s. Maximum intensity projection images and subtracted source images were compared with those obtained by conventional angiography.
In all cases, the presence or absence of abnormalities in the targeted vessels, as well as the morphology of the sagittal sinuses, was clearly visualized as in conventional angiography, without any obstructions such as hyperintense hematomas or thrombi, or intraluminal turbulence. Although the temporal and spatial resolutions with current hardware are insufficient, these preliminary results suggest that dynamic contrast-enhanced MRA with subtraction may be useful for assessing vascular lesions with hemorrhage or thrombus, and the dural sinuses.
Analysis of flow dynamics of main pulmonary artery by cine phase contrast MR angiography. Retrospective EKG gating was used. Mean velocity, maximum velocity, and maximum flow rate of MPA were 6. Retrograde flow in the MPA was noted to begin at late-to mid-systole. MR angiography in the evaluation of a renovascular cause of neonatal hypertension.
The gold standard for diagnosing renovascular disease is conventional renal angiography. However, in neonates the procedure is not commonly used because of its invasive and technically challenging nature. The infant underwent partial nephrectomy with subsequent resolution of his hypertension. Clinical application of gadolinium-enhanced three-dimensional pulmonary MR angiography. Twenty-nine patients with suspected pulmonary lesions, and three normal volunteers, underwent gadolinium-enhanced three-dimensional 3D pulmonary MR angiography MRA.
The MRA were obtained during intravenous administration of gadolinium-based contrast material, in a single breath-hold. Conspicuity of the normal pulmonary segmental arteries was estimated on the MRA.
Abnormal findings such as ''vascular involvement'', ''abnormal connection'', stenosis'', or ''dilatation'' on the MRA were compared with those on conventional angiography or CT. Normal pulmonary segmental arteries, except for A 4,5,6,8and9 of the left pulmonary artery, could be clearly visualized. Blind reading of four different findings lead to characteristic findings for each pulmonary disease that can be aid in their differential diagnoses.
This technique shows promise as a noninvasive diagnosis of lung diseases. Dynamic coronary MR angiography in a pig model with hyperpolarized water. To investigate dynamic coronary MR angiography using hyperpolarized water as a positive contrast agent. Hyperpolarization can increase the signal by several orders of magnitude, and has recently been translated to human cardiac application. The aim was to achieve large 1 H signal enhancement Protons in D2 O were hyperpolarized by dissolution dynamic nuclear polarization.
The MRI images were acquired The acquisition time was ms per frame. Coronary angiographic images with a signal TOF MR angiography of cerebral arteriovenous malformations before and after radiotherapy. They were compared to conventional angiography to assess the MRA study.
In combination with the MRI study, an important 3D dataset for treatment planning could be obtained that includes therapeutically relevant information on the localization and spatial structure of the AVM as well as the adjacent brain tissue.
As a noninvasive technique, close-meshed follow-up studies could be performed with MRA. MR angiography of the carotid arteries and intracranial circulation: Several studies have shown the usefulness of contrast-enhanced MR angiography CE-MRA for imaging the supraortic vessels, and, as a consequence, it has rapidly become a routine imaging modality. The main advantage over unenhanced techniques is the possibility to acquire larger volumes, allowing demonstration of the carotid artery from its origin to the intracranial portion. Most published studies on CE-MRA of the carotid arteries have been performed with standard Gd-based chelates whose T1 relaxivity values are similar.
When administered at an equivalent dose to that of a standard agent, these newer contrast agents produce significantly greater intravascular signal enhancement. The availability of an appropriate high-relaxivity contrast agent might also help to overcome some of the intrinsic technical problems e. To avoid the problem of superimposition of veins, ultrafast gradient echo MRA techniques with very short TR and TE have been developed. Although the precise sequence parameters vary between manufacturers, they are basically similar.
The choice between performing a time-resolved or high spatial resolution CE-MRA examination depends upon the precise clinical application. The most common applications include the study of cerebral aneurysms, arteriovenous malformations, dural arteriovenous fistulas and dural venous diseases.
Renal contrast-enhanced MR angiography: To investigate bolus timing artifacts that impair depiction of renal arteries at contrast material-enhanced magnetic resonance MR angiography and to determine the effect of contrast agent infusion rates on artifact generation. Renal contrast-enhanced MR angiography was simulated for a variety of infusion schemes, assuming both correct and incorrect timing between data acquisition and contrast agent injection.
In addition, the ethics committee approved the retrospective evaluation of clinical breath-hold renal contrast-enhanced MR angiographic studies obtained with automated detection of contrast agent arrival. Twenty-two studies were evaluated for their ability to depict the origin of renal arteries in patent vessels and for any signs of timing errors. Simulations showed that a completely artifactual stenosis or an artifactual overestimation of an existing stenosis at the renal artery origin can be caused by timing errors of the order of 5 seconds in examinations performed with contrast agent infusion rates compatible with or higher than those of hand injections.
Lower infusion rates make the studies more likely to accurately depict the origin of the renal arteries. In approximately one-third of all clinical examinations, different contrast agent uptake rates were detected on the left and right sides of the body, and thus allowed us to confirm that it is often impossible to optimize depiction of both renal arteries.
In three renal arteries, a signal void was found at the origin in a patent vessel, and delayed contrast agent arrival was confirmed. Computer simulations and clinical examinations showed that timing errors impair the accurate depiction of renal artery origins. Comparison of two-dimensional MR angiography and microsphere measurement of renal blood flow for detection of renal artery stenosis.
This paper compares depiction of the renal arteries by MR angiography to renal blood flow as determined with microspheres in a dog model of renal artery stenosis. A left renal artery stenosis was created by placement of a silk ligature. Nblabeled microspheres were injected into the left ventricle and a reference blood sample was drawn.
The dog was imaged in the 1. The kidneys were excised, weighted, divided into sections, and counted. Two dogs were studied to date. Preoperative evaluation of neurovascular relationship by using contrast-enhanced and unenhanced 3D time-of-flight MR angiography in patients with trigeminal neuralgia. Background Microvascular decompression is an etiological strategy for the therapy of trigeminal neuralgia TN. Preoperative identification of neurovascular compression, therefore, could have an impact on the determination of appropriate treatment for TN.
Purpose To evaluate the value of contrast-enhanced and unenhanced three-dimensional 3D time-of-flight TOF MR angiography in the visualization of neurovascular relationship in patients with TN. Images were reviewed by a radiologist blinded to clinical details. Vascular contact with the trigeminal nerve was identified, and the nature of the involved vessels artery or vein was determined.
All patients underwent microvascular decompression. Results In 37 patients with TN, contrast-enhanced 3D TOF MR angiography identified surgically verified neurovascular contact in 35 of 36 symptomatic nerves, and there was no false-positive. Based on surgical findings, the sensitivity of MR imaging was The nature of the offending vessel was correctly identified in Conclusion Contrast-enhanced 3D TOF MR angiography is useful in the detection of vascular contact with the trigeminal nerve in patients with TN, and this MR imaging in combination with unenhanced MR angiography could help in the identification of the nature of the responsible vessels.
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Retrograde flow in the dural sinuses detected by three-dimensional time-of-flight MR angiography. Retrograde flow in the left dural sinuses is sometimes detected by three-dimensional time-of-flight 3D-TOF magnetic resonance MR angiography. The purpose of this study was to evaluate the incidence of this phenomenon and its characteristic features on 3D-TOF MR angiograms.
We retrospectively reviewed cranial MR angiography images of 1, patients examined at our institution. All images were obtained by the 3D-TOF technique with one of two 1. Maximum intensity projection MIP images in the horizontal rotation view were displayed stereoscopically. We reviewed the source images, inferosuperior MIP images, and horizontal MIP images and identified retrograde flow in the dural sinuses. We found retrograde flow in the dural sinuses of 67 patients on the source images from 3D-TOF MR angiography ; the incidence was 6.
In 47 of the 67 patients, retrograde flow was identified in the left inferior petrosal sinus, in 13, it was seen in the left sigmoid sinus, and in 6, it was seen in the left inferior petrosal and left sigmoid sinuses. The remaining patient had retrograde flow in the left inferior petrosal and left and right sigmoid sinuses. The mean age of the patients with retrograde flow was slightly greater than that of the patients without this phenomenon 70 years vs 63 years.
Retrograde flow in the dural sinuses frequently occurs on the left side in middle-aged and elderly patients during 3D-TOF MR angiography performed with the patient in the supine position. This phenomenon should not be misdiagnosed as a dural arteriovenous fistula. Technique for arterial-phase contrast-enhanced three-dimensional MR angiography of the carotid and vertebral arteries.
Our goal was to evaluate whether contrast-enhanced three-dimensional MR angiography using the MR Smartprep technique would enable us to obtain arterial-phase MR angiograms of the carotid and vertebral arteries. The study included 35 patients with suspected lesions of the neck in whom the MR Smartprep technique was used for MR angiography performed with a 1. The tracker volume was placed primarily in the middle part of the right common carotid artery.
The imaging volume was placed in a coronal direction to include the carotid and vertebral arteries from the aortic arch to the skull base. A centric phase-ordering scheme was used. Imaging times were 20 to 38 seconds for 14 patients and 11 to 16 seconds for 21 patients. Contract-enhanced 3-D MR angiography with the MR Smartprep technique was useful for showing arterial-phase carotid and vertebral arteries selectively.
Pulmonary MR angiography and perfusion imaging—A review of methods and applications. The pulmonary vasculature and its role in perfusion and gas exchange is an important consideration in many conditions of the lung and heart. Currently the mainstay of imaging of the vasculature and perfusion of the lungs lies with CT and nuclear medicine perfusion scans, both of which require ionizing radiation exposure.
Here we review MRI methods for imaging the pulmonary vasculature and pulmonary perfusion, both using contrast enhanced and non-contrast enhanced methodology. In many centres pulmonary MR angiography and dynamic contrast enhanced perfusion MRI are now well established in the routine workflow of patients particularly with pulmonary hypertension and thromboembolic disease.
However, these imaging modalities offer exciting new directions for future research and clinical use in other respiratory diseases where consideration of pulmonary perfusion and gas exchange can provide insight in to pathophysiology. MR angiography in the diagnosis of cerebral venous angiomas: We collected ten cases who demonstrated developmental venous anomaly on MR image.
TOF without enhancement in five. On enhanced 3D TOF, both dilated collecting veins and medullary veins were well depicted in five of six cases, however, the signal intensity of the collecting and medullary veins are less than arteries. Contrast-enhanced thoracic 3D- MR angiography in infants and children. To optimise breath-hold contrast-enhanced MR angiography MRA in infants and children with suspected congenital heart or thoracic vessel malformation. Thirty-nine children median age 1 year were examined, using five different ultrafast MRA sequences with a TR between 3.
A test injection was used to determine contrast travel time. Different parameters for contrast injection were evaluated. Signal-to-noise ratio SNR measurements were performed and image quality and injection timing were evaluated. The mean contrast dose was 0. The mean scan time was Highest spatial resolution was obtained with TR 4. A contrast dose of 0. The scan delay time should equal the contrast travel time for optimal vessel enhancement. In the future, contrast-enhanced MRA may be a potential alternative to angiocardiography in infants and children.
Accuracy of 3 T MR angiography in vertebral artery stenosis and coincidence with other cerebrovascular stenoses. The purpose of this study was to determine the diagnostic accuracy of CE-MRA at 3 T in the evaluation of ostial stenosis of VA and to find associated coincidental stenoses using logistic regression analysis. Ostial stenosis on MRA was correlated with coincidental lesions in intracranial and cervical arteries by logistic regression analysis. In case of significant stenoses, CE-MRA showed a tendency of overestimation with a false-positive rate of The role of MR imaging and MR angiography.
MRI in cardiac disease has been established as the non-invasive standard of reference in many pathologies. However, in acute chest pain the situation is somewhat special since many of the patients presenting in the emergency department suffer from potentially life-threatening disease including acute coronary syndrome, pulmonary embolism, and acute aortic syndrome. Those patients need a fast and definitive evaluation under continuous monitoring of vital parameters. Due to those requirements MRI seems to be less suitable compared to X-ray coronary angiography and multislice computed tomography angiography CTA.
However, MRI allows for a comprehensive assessment of all clinically stable patients providing unique information on the cardiovascular system including ischemia, inflammation and function. This review addresses specific features of MRI and MRA for different cardiovascular conditions presenting with acute chest pain. Usefulness of MR angiography with fat- and water-suppression technique. The purpose of this study was to improve visualization of intracranial vessels by the use of time-of-flight MR angiography with the fat- and water-suppression technique TOF-MRA-presat.
Two groups of individuals were studied. They were 35 patients with ischemic cerebrovascular disorders lacunar group and 22 volunteers control group. The contrast between background tissue and blood vessels was thus improved. The visibility of the ophthalmic artery, the posterior communicating artery, and the superior cerebellar artery in the control group increased noticeably in the TOF-MRA-presat images as compared with the TOF-MRA images.
Similarly, the visibility of the insular segment of the middle cerebral artery, the posterior temporal artery, and the calcarine artery in the lacunar group was also better in TOF-MRA-presat images than in TOF-MRA-images.
Evaluation of paraclinoid aneurysm by using contrast-enhanced MR angiography. Juxta-dural ring aneurysms of the internal carotid artery have different clinical courses and risks of subarachnoid hemorrhage SAH depending upon their positions in the intradural or extradural spaces. Imaging parameters were as follows: When the hyperintensity of the aneurysm was located within the hyperintensity of the contrast-enhanced cavernous sinus, we diagnosed the lesion as an intracavernous, ''extradural'' aneurysm.
Seven patients out of 18 were treated surgically. In all, MRI findings corresponded well with the operative findings. Branching pattern of lenticulostriate arteries observed by MR angiography at 3. We hypothesized that the pattern of branching of the lenticulostriate arteries LSAs is involved in the variation of the distribution of the infarction within the LSA region. Visualization of LSAs was possible in Evaluation of MR angiography and blood flow measurement in abdominal and peripheral arterial occlusive disease.
To assess the characteristics of blood flow measurement with MR Angiography MRA to evaluate the status of vascular stenoses, two or three dimensional time-of-flight MRA and velocity-encoded cine MR were performed in the segments of 35 patients, with abdominal and peripheral arterial occlusive diseases.
In 11 of these 35 patients digital subtraction angiography was additionally underwent, and the stenotic findings was compared with MRA. In summery, MRA was considered as useful examination to assess the degree of the vascular stenoses in abdominal and peripheral arterial occlusive disease. Evaluation of renal vascular in living donors before transplantation using dynamic contrast enhanced MR angiography. Thirty five healthy living renal donor candidates were scanned on MR system before transplantation.
Thus, the imaging of the renal arterial, venous and collecting systems were got. Two radiologists observed renal arteries and veins on original imaging and MIP reconstmcted imaging. The quality of MR angiography was evaluated on a five- point scale and the vascular anatomy or variations of the arterial and venous systems were recorded, using intraoperative findings as a standard of reference.
The quality for all MRA was good or very good for the most of living renal donors. Among 70 renals, several variations of vascular were found, including 5 left accessory artery, 9 right accessory artery, 3 left proximal arterial branch and 6 right proximal arterial branch. Among 70 renal veins, 1 right accessory veins and 2 left varicocele were observed. DCE MRA was noninvasive tool for evaluation of the renal vasculature and variations with high accuracy. It would be a good modality in preoperative evaluation of living renal donors.
The diagnostic value of three-dimensional dynamic contrast-enhanced MR angiography for intracranial aneurysms. Then conventional digital subtraction angiography DSA and feasible endovascular treatment were performed simultaneously. The source images were subtracted from mask images and transferred to computer workstation. All images were subsequently post-processed using three-dimensional reconstruction.
There were 39 cases with 45 intracranial aneurysms. But the diagnosis should be very carefully made for small aneurysms located in the periphery and the arterial bifurcation. Its three dimensional information is helpful for DSA demonstration and treatment planning. Any uncertain diagnosis requires DSA confirmation.
Evaluation of three-dimensional contrast-enhanced MR angiography in pediatric body vascular lesions. Evaluation of three-dimensional contrast-enhanced MR angiography in the pediatric body vascular lesions. This study examined the usefulness of three-dimensional gadolinium-enhanced magnetic resonance angiography 3D-enhanced MRA for pediatric body vascular lesions.
Maximum intensity projection MIP and multiplanar reconstruction MPR images were obtained from the imaging data in all cases, and eleven MIP images were obtained after subtraction of precontrast-enhanced imaging data from postcontrast-enhanced imaging data. In six cases, MIP and MPR images were correlated with cine or digital subtraction angiographies, and the eleven subtracted MIP images were compared with those before subtraction. It was considered that 3D-enhanced MRA was useful for pediatric body vascular lesions because of advantages such as lower invasiveness compared with that of conventional angiography, absence of radiation exposure, safety of contrast media, easy availability of MPR images, and short scanning time.
In conclusion, if a pediatric body vascular lesion is suspected, 3D-enhanced MRA should be performed before conventional angiography. It also seems that 3D-enhanced MRA may be useful for follow-up. Variations of the posterior cerebral artery diagnosed by MR angiography at 3 tesla. Fenestration, early bifurcation, and duplication of the posterior cerebral artery PCA and the so-called hyperplastic anterior choroidal artery AChA , considered a variation of the PCA, are rare.
We evaluated the prevalence and characteristic features of these PCA variations on magnetic resonance MR angiography. We reviewed intracranial MR angiographic images of patients examined using a 3-tesla scanner. Images from the skull base to the intracranial region were obtained using the standard time-of-flight technique. We excluded images of 52 patients with insufficient image quality or occlusion of the PCA s and retrospectively evaluated the images of patients using a picture archiving and communication system.
We observed PCA fenestration in eight 0. We observed PCA variations in 30 1. The evaluation of three-dimensional dynamic contrast enhanced MR angiography in portal hypertension. To evaluate the techniques of three-dimensional dynamic contrast enhanced MR angiography 3D DCE MRA with normative timing of sequences, enhancive 3D slab thickness and subtraction in portosystemic collaterals.
Before April , 12 patients were performed with mm of 3D slab thickness and repeated sequences estimated by breath, after April , 18 patients were performed with mm of 3D slab thickness and 5 normative repeated sequences respectively at 0, 20, 40, 60 and 90 s. After subtracting selective arterial phase images from subsequent portal venous phase images, two radiologists assessed visualization of portal collaterals independently with a four - point scale for ranking of image quality in maximum intensity projection MIP images with and without subtraction.
Average scores for image quality in visualization of the portal vein with subtraction were significantly depressed compared with the scores without subtraction 2. To develop a robust and efficient reconstruction framework that provides high-quality motion-compensated respiratory-resolved images from free-breathing 3D whole-heart Cartesian coronary magnetic resonance angiography CMRA acquisitions.
Here, a reconstruction framework for Cartesian CMRA imaging is proposed, which provides respiratory-resolved motion-compensated images by incorporating 2D beat-to-beat translational motion information to increase sparsity in the respiratory dimension. The motion information is extracted from interleaved image navigators and is also used to compensate for 2D translational motion within each respiratory phase. The proposed XD-ORCCA provides high-quality respiratory-resolved images, allowing clear visualization of the right and left coronary arteries, even for irregular breathing patterns.
A robust respiratory-resolved motion-compensated framework for Cartesian CMRA has been proposed and tested in healthy subjects and patients. The proposed XD-ORCCA provides high-quality images for all respiratory phases, independently of the regularity of the breathing pattern. Evaluation of the early enhancement of coronary atherosclerotic plaque by contrast-enhanced MR angiography.
To evaluate the early enhancement of coronary atherosclerotic plaque using contrast-enhanced MR angiography CE-MRA and investigate the association between unstable angina pectoris UAP and early enhancement of the plaque. Contrast-to-noise ratio of the culprit plaque guided by CTA was measured on a cross-sectional multi-planar reconstruction image of the plaque on both pre- and post-CE-MRA. The association between early enhancement of the plaques and UAP was analyzed. Thirty-seven non-calcified plaques with significant coronary stenosis were detected in the 37 patients on MRA. Of the 37 plaques on CE-MRA, 13 and 24 plaques presented early enhancement and no enhancement, respectively.
This study was aimed at testing the value of image subtraction for evaluating carotid vessel wall enhancement in contrast-enhanced MR angiography MRA. IRB approval was obtained. The scans of 81 consecutive patients who underwent carotid MRA with 0. Axial carotid 3D T1-weighted fast low-angle shot sequence before and 3 min after contrast injection were acquired and subtracted enhanced minus unenhanced. Vessel wall enhancement was assigned a four-point score using native or subtracted images from 0 no enhancement to 3 strong enhancement.
Halle-Wittenberg Germany ; Kornhuber, M. Halle-Wittenberg Germany ; Keysser, G. An inflammatory, embolic, neurodegenerative or metastatic origin of these lesions was excluded by extensive clinical studies. In patients suspected of having a vasculitis or vasculitis-like angiopathy, MRA is recommended as a non-invasive modality. If the results of MRI and extensive clinical studies are carefully correlated, MRA may substitute conventional angiography in cases with typical vascular changes.
To assess in vivo 1 MR-guided percutaneous transluminal renal angioplasty PTRA in experimental bilateral rabbit renal artery stenosis RAS ; 2 postprocedural follow-up by gadolinium-enhanced MR angiography versus histomorphometry. Fifteen male NZW rabbits of mean weight 4. After 4 weeks the rabbits were randomized into two groups: After another 4 weeks the rabbits were killed to assess by histomorphometry recurrent stenosis and contralateral induction injury stenosis lesions. RAS induction was successful in all cases. Fourteen arteries developed restenosis and 13 only initial stenosis.
Five to eight steps were required for balloon localization and inflation for each PTRA. The value of applying nitroglycerin in 3D coronary MR angiography with real-time navigation technique. Nitroglycerin administration results in dilation of epicardial coronary vessels and in an increase in coronary blood flow, and has been suggested to improve MR coronary angiography.
This study evaluates systematically whether administration of nitroglycerin improves the visualization of coronary arteries and, as a result, the detection of coronary artery stenosis during free breathing 3D coronary MR angiography. Coronary MR angiography was performed in 44 patients with suspected coronary artery disease at a 1.
Catheter coronary angiography was used as a gold-standard. There was also no significant difference in the coronary MR angiography with and without nitroglycerin in the average qualitative assessment score of the visualization of LM, proximal LAD, proximal CX, and proximal and distal RCA 2.
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Administration of nitroglycerin does not improve visualization of the coronary arteries and. The clinical value of three-dimensional contrast-enhanced MR angiography in abdominal aortic aneurysms. A bolus-test was done before angiography to optimize imaging delay time. The source images were subtracted from mask images and transferred to computer workstation, and subsequently post-processed using 3D reconstruction. All sequences were used to depict the type, location, extent, and thrombosis of the AAA, the morphology of its proximal neck, the distal aortoiliac inflow tract, and the relationship with the branches of aorta.
The length, diameter, and angle of the aneurysm sac, and proximal and distal arteries were measured. The clinical role was evaluated for treatment planning. The mean diameter of aneurysms was 5. The thrombosis was thicker than 2. The accurate parameters needed by endovascular treatment were gained simultaneously. The endovascular and surgical treatment were selected according the images 31 endovascular treatment, 4 surgical treatment, 28 conservative treatment only.
MR angiography of the cerebral vessels with inflow-increased visualization by overcontiguous imaging and advanced processing. The purpose of this study was to increase the visualization of cerebral vessels with MR angiography by using an inflow technique from transverse sections. Difficulties with visualization include the tortuous nature of the vessels and slow blood flow. The MR method is a transverse two-dimensional multiple single-section sequence with a velocity-compensated gradient echo and presaturation.
A S15 imager with mTm gradients and a prototype angiographic package is used. Overcontiguous acquisition yields smaller effective center-to-center sections. Interpolation is used to generate interleaved plane projections. A combination of image parameter swill reduce the level of the stationary tissue relative to the flowing blood. Interpolation of the MR images will further reduce this artifact, giving the vessels a smooth structure.
MR angiography of the brain performed with an inflow technique allows the visualization of vessels in the brain even if the vessels follow tortuous paths. Presaturation and user-defined regions of interest can be used for ease of interpretation. Coronary Artery Anomalies and Variants: The purpose of this study was to prospectively use a whole-heart three-dimensional 3D coronary magnetic resonance MR angiography technique specifically adapted for use at 3 T and a parallel imaging technique sensitivity encoding to evaluate coronary arterial anomalies and variants CAAV.
This HIPAA-compliant study was approved by the local institutional review board, and informed consent was obtained from all participants. Twenty-two participants 11 men, 11 women; age range, 18—62 years were included. Ten participants were healthy volunteers, whereas 12 participants were patients suspected of having CAAV. A 3D free-breathing navigator-gated and vector electrocardiographically—gated segmented k-space gradient-echo sequence with adiabatic T2 preparation pulse and parallel imaging sensitivity encoding was used.
Findings included aneurysms, ectasia, arteriovenous fistulas, and anomalous origins. Assessment of the signal intensity distribution pattern within the unruptured cerebral aneurysms using color-coded 3D MR angiography. Patterns were categorized into central-type, neck-type and peripheral-type according to the distribution of MR signals with low-, moderate- and high signal intensity areas.
Imaging analysis revealed the significant relationship P MR angiography may provide patient-specific analysis of intraaneurysmal flow status in relation to the morphological change of the corresponding aneurysmal dome in the management of unruptured cerebral aneurysms. Usefulness of three-dimensional contrast-enhanced MR angiography in the evaluation of pelvic and lower extremity arteries. To evaluate the feasibility and clinical usefulness of three-dimensional contrast-enhanced MR angiography 3D-CE-MRA as a screening test in the evaluation of pelvic and lower extremity arterial diseases.
Coronal 3-dimensional gradient-echo, pre-and post contrast image were acquired with a dedicated peripheral vascular coil and moving-bed technique on a 1. Timing of start of data acquisition was determined by MR fluoroscopy technique, and 0. For quantitative analysis, signal to noise ratio SNR and artery to soft tissue contrast to noise ratio CNR of lower extremities arterial system including lower abdominal aorta were calculated.
For qualitative analysis, arterial systems were divided into six segments, and were evaluated in terms of conspicuity of arterial systems and the degree of venous enhancement by three- and four-point scale respectively. In eight patients who underwent both MR angiography and conventional angiography as standard reference. Imaging analysis was done by means of consensus between two experienced radiologists. The mean SNR of arterial system was Among the total arterial segments arterial segments Obgleich wir wissen, dass Computer kein Bewusstsein besitzen, behandeln wir sie oft in einer Weise, die die Grenze zwischen Dingen und Menschen verwischt.
Wir sind bereit zuzugeben, dass die Maschine eine 'Psyche' hat, nicht jedoch, dass sie lebendig sein kann. Die Versessenheit, mit der man in MUDs versucht, Leute dadurch 'greifbar' zu bekommen, dass man ihr Geschlecht bestimmt, erinnert daran, wie sehr wir im wirklichen Leben Geschlechterrollen zur Festlegung unserer Beziehungen benutzen. Die heutigen Kinder betrachten Maschinen als intelligent und bewusst, aber nicht als lebendig. Und genau dazu veranlasst uns die Kultur der Simulation. Interaktiv und reaktiv, vermittelt er die Illusion einer Gemeinschaft ohne die Forderungen der Freundschaft.
Andererseits spielen wir mit Computerprogrammen, die wir als lebendig oder fast-lebendig betrachten. Hochschulen im Strudel des Leitmedienwechsels Halbinsel Au, Informatische Bildung auf der Primarstufe: Aus dem fernen Digitalien Commodity and Community in Personal Computing: Gesamtes Buch als Volltext: Homepage von Sherry Turkle: Professor Reconsiders Children's Online Lives: Artikel in der NY Times vom Priscillas Tagebuch vom Epistemological pluralism and the revaluation of the concrete Sherry Turkle , Seymour Papert erschienen in Constructionism.
Sociable Technologies - Enhancing Human Performance when the computer is not a tool but a companion erschienen in Converging Technologies for Improving Human Performance. Turing suggests that if under these circumstances you cannot decide which is the computer and which is the person, you will have to conclude that the machine is intelligent: Personen KB IB clear. Kenneth Gergen , Jean Piaget.
Texte KB IB clear. Aspekte des Selbst , Children Philosophers. Fragen KB IB clear. Kann ein Computer Geist besitzen? Aussagen KB IB clear. Begriffe KB IB clear. Epistemological pluralism and the revaluation of the concrete: