Congenital heart disease.
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Heart Defects, Congenital↗
Biomedical subjects
K M Link
Publications and source records attributed to K M Link.
Magnetic resonance imaging of the mediastinum.
Magnetic resonance (MR) imaging is becoming a primary modality for evaluating the mediastinum. MR affords multiplanar imaging capabilities without exposing patients to ionizing radiation. The inherent contrast effect of different mediastinal tissues sharply delineates anatomic structures on MR images without contrast enhancement. Gradient-echo and phase-mapping techniques permit noninvasive qualitative and quantitative assessment of mediastinal blood flow. High soft tissue contrast and flow analysis capabilities make MR imaging a valuable modality for evaluating mediastinal vascular disorders. Various mediastinal tumors and their extent are best identified by the use of T1-weighted, T2-weighted, and gadolinium-enhanced images. Both primary and secondary chest wall lesions may be assessed with standard spin-echo MR images. Complex pleuroparenchymal lesions may be evaluated by means of a multiplanar approach and modified pulse sequences. This article addresses the technical parameters governing MR imaging of the mediastinum and describes MR characteristics of various pathologic conditions.
Humans↗
Magnetic resonance imaging evaluation of recipient for cryopreserved aortic allograft.
Aortic valve replacement with a cryopreserved aortic allograft is the procedure of choice for many patients with aortic valvular heart disease. We have used magnetic resonance imaging preoperatively to determine annular size and coronary artery orientation in the recipient, which not only has enabled us to select an allograft of appropriate size from a distant tissue bank, but also has helped us to identify preoperatively the recipient with a truly bicuspid valve in which the coronary arteries are oriented 180 degrees apart. Sixteen consecutive patients were evaluated preoperatively, the aortic annulus being measured with both magnetic resonance imaging and echocardiography. Cryopreserved aortic allografts were ordered on the basis of the magnetic resonance imaging measurement. Annular size was then measured intraoperatively with calibrated sizers. Magnetic resonance imaging annular measurements correlated highly with those found at operation (r = 0.92), whereas echocardiographic measurements correlated less well (r = 0.69). Coronary orientation was accurately predicted in every case (r = 1.0). Therefore, we have found magnetic resonance imaging to be useful in the preoperative evaluation of patients for aortic valve replacement with a cryopreserved aortic allograft.
Adolescent↗
Cardiopulmonary vascular imaging.
Magnetic resonance angiography (MRA) effectively maximizes the flow sensitivity of MR imaging (MRI) to display the body's vasculature. Although MRA has proven quite effective in imaging the intracranial and extracranial vessels, cardiopulmonary MRA faces several additional inherent challenges. Cardiorespiratory motion, vessel pulsatility, and irregular flow patterns all degrade image quality and necessitate appropriate compensation schemes. Although preliminary cardiopulmonary MRA methods appear promising, near instantaneous scan times may be necessary to fully maximize the potential of this technique. Multislice spin-echo and gradient-echo techniques have also proven effective. These methods may compensate for cardiac motion through either ECG-gating or referencing, and may maximize the signal characteristics from the intrinsic slow blood flow of the pulmonary vasculature. Phase velocity mapping techniques, which have proven capable of quantifying blood flow in the body, appear equally promising in preliminary studies in evaluating the cardiopulmonary vascular system. Because of the nature of blood flow dynamics in the cardiopulmonary vascular system, spin-echo (SE), gradient refocussed echo (GRE), and possibly phase mapping technique appear well suited for evaluating these regions.
Artifacts↗
The role of MR imaging in the evaluation of acquired diseases of the thoracic aorta.
Because MR imaging combines the major attributes of angiography, echocardiography, and CT, its role in the evaluation of the thoracic aorta is steadily increasing. When standard spin-echo techniques are used, flowing blood produces a signal void that allows excellent depiction of the anatomy and simultaneous evaluation of the lumen, vessel wall, and periaortic structures. On dynamic or cine MR, flowing blood generates a signal that allows visualization of the blood as it pulsates through the aorta. Turbulent blood generates a signal void, thereby allowing the detection and qualitative assessment of the pathophysiologic consequences of anatomic abnormalities. With phase-mapping techniques, blood velocity can be measured and used to calculate pressure gradients. Recent advances in the field of MR angiography will greatly enhance the overall role of MR in the evaluation of the thoracic vasculature by allowing detection and assessment of the branch vessels. Although the technique is still evolving, it has shown extraordinary potential as a tool for studying the thoracic aorta. The exact role of MR in patient care will depend on advances in transesophageal echocardiography. However, it is not unreasonable to think that someday MR imaging will be the primary technique for evaluation of the thoracic aorta.
Aorta, Thoracic↗
Magnetic resonance imaging in the evaluation of congenital heart disease.
Magnetic resonance imaging is a powerful tool for studying patients with congenital heart disease. Its phenomenal contrast resolution, improved spatial resolution, and large field-of-view allow for graphic depiction of a wide array of congenital defects. Although this method was originally handicapped by the time it took to perform an exam and by poor image quality, advances in hardware and software coupled with attention to technique have led to a reliable diagnostic imaging modality. Although the technology is still evolving, it is not unreasonable to hope that the noninvasive imaging modalities of magnetic resonance and echocardiography will ultimately replace angiography in the evaluation of congenital heart disease.
Heart↗
Clinical utility of three-dimensional magnetic resonance angiographic imaging.
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Adolescent↗
Computer-assisted assessment of the kinetic function of disk-type artificial heart valves.
A simple and accurate computer simulation method was developed to evaluate the geometrical parameters of disk-type artificial heart valves from cinefluorographic recordings. In vitro valve models with preset occluder angles were used to test the accuracy of the method. Linear regression analysis produced slope 1.00055 and intercept 0.0402, with r = 0.999. In vivo reproducibility was tested through repeated measurements, taken several weeks apart, of OMS valves in situ. Regression with slope 1.02 and intercept -0.95, r = 0.95 were found.
Computer Simulation↗
Noninvasive evaluation of the pericardium and myocardium.
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Cardiomyopathies↗
MR imaging of the criss-cross heart.
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Crisscross Heart↗
MR imaging in congenital heart disease: where is the leading edge?
MRI has proved to be a useful tool in the evaluation of congenital heart disease. Two types of information can be gleaned from this new imaging modality. The first has to do with the acquisition of anatomical details which are best retrieved from "static" scanning using a low field strength. We have found magnetic resonance to be superior to angiocardiography and/or echocardiography in gathering anatomical information in the following situations: congenital heart defects having giant compartments; conotruncal malformations; and assessment of surgical results. Secondly, physiological information can be obtained using "dynamic" or cine magnetic resonance imaging, utilizing a high field strength.
Heart Defects, Congenital↗
Reconstruction of the four basic cardiac projections from magnetic resonance images: a new aspect.
From 3D MR scans, the authors have constructed 2D "silhouettes" that correspond to standard radiographic views of the heart. These images explicitly demonstrate the relationship of the surface anatomy to the internal anatomy of the heart and serve to indicate what chambers contribute to the heart borders seen on radiographs. The findings depart from conventional wisdom in at least four respects, including: the left atrium contributes to the left heart border in a frontal radiograph in only a minority of subjects, in steep RAO and lateral radiographs, the right ventricle does not always form the anterior heart border, in left anterior oblique radiographs greater than 30 degrees, the anterior heart border is formed predominantly by the right ventricle, and the left ventricle extends more craniad along the posterior margin of the heart than expected.
Heart↗
MR imaging of Ebstein anomaly: results in four cases.
We performed ECG-gated MR imaging in four patients (4 months-15 years old), all of whom had a previously diagnosed severe form of Ebstein anomaly of the tricuspid valve. The goal was to study the anatomy of this congenital heart defect with MR imaging. The axial and coronal scans provided the best details. All characteristic abnormalities were seen well: the maintained proximal and faulty distal attachment of the anterior tricuspid leaflet, the absence of both septal and posterior tricuspid leaflets, the size and delineation of the anatomically atrialized chamber of the right ventricle, and the small, compressed trabecular portion with the markedly dilated pumping outflow tract of the right ventricle proper. Our results suggest that MR may furnish valuable information in patients with Ebstein anomaly when echocardiography is either inconclusive or technically difficult to perform.
Adolescent↗
A persistent fifth aortic arch in man: a double-lumen aortic arch (presentation of a new case and review of the literature).
Persistent fifth aortic arch manifested as a double-lumen aortic arch (DLAA) is a rare anomaly. We present such a case with transposition of the great arteries, ventricular septal defect (VSD), and pulmonary atresia. Review of the eight previously published cases indicates relatively frequent association of DLAA with preductal coarctation of the aorta. We attempt to explain the coexistence of this lesion with DLAA. We also discuss evidence supporting derivation of the inferior channel of the DLAA from the embryologic fifth aortic arch.
Aorta, Thoracic↗
MR imaging of the central pulmonary arterial tree in conotruncal malformation.
Successful MR imaging of the central pulmonary arterial tree was performed in four cases of conotruncal malformation and in one case of pulmonary arterial banding. Angiography performed near the time of MR imaging in three cases and 15 years earlier in two other cases did not visualize the central pulmonary arterial tree. Multiplanar imaging was necessary to fully visualize the anatomy of complex congenital defects of the pulmonary arterial tree; the choice of imaging plane varied depending on the portion of the pulmonary artery to be evaluated.
Adult↗
Metastatic involvement of the heart and pericardium: CT and MR imaging.
Metastases to the heart and pericardium are much more common than primary cardiac tumors and are generally associated with a poor prognosis. Tumors that are most likely to involve the heart and pericardium include cancers of the lung and breast, melanoma, and lymphoma. Tumor may involve the heart and pericardium by one of four pathways: retrograde lymphatic extension, hematogenous spread, direct contiguous extension, or transvenous extension. Metastatic involvement of the heart and pericardium may go unrecognized until autopsy. Impairment of cardiac function occurs in approximately 30% of patients and is usually attributable to pericardial effusion. The clinical presentation includes shortness of breath, which may be out of proportion to radiographic findings in patients with pericardial effusion or may be the result of associated pleural effusion. Patients may also present with cough, anterior thoracic pain, pleuritic chest pain, or peripheral edema. The differential diagnosis of pericardial effusion in a patient with known malignancy includes malignant pericardial effusion, radiation-induced pericarditis, drug-induced pericarditis, and idiopathic pericarditis. Any disease process that causes thickening or nodularity of the pericardium or myocardium or masses within the cardiac chambers can mimic metastatic disease.
Diagnosis, Differential↗
Thoracic aortic disease: evaluation using a single MRA volume series.
OBJECTIVE: Use of MRA for thoracic aortic disease (TAD) evaluation has been limited. This report describes an initial experience with TAD evaluation using a single MRA volume series. MATERIALS AND METHODS: A single volume series, based on sequential 2D TOF MRA, was acquired in 30 cases (28 with suspected TAD and 2 normals). Each series was processed using multiplanar reconstruction (MPR) and maximum intensity projection (MIP); resulting tomographic (one base and two MPR) and MIP sets were blindly interpreted by four reviewers to detect TAD and, if present, to diagnose its specific form. For cases incorrectly interpreted, the standard MR images were subsequently interpreted. RESULTS: The TAD categories included aneurysm (n = 13), dissection (n = 9), and arch anomalies (n = 5). Sensitivities were high for TAD overall (89-100%) and TAD in ascending and descending portions; sensitivities were lower for TAD of the arch (two of four reviewers > or = 90% for TAD overall and descending TAD). Specificities for TAD overall had a wider range (67-100%), but were high for ascending, arch, and descending portions (three to four of four reviewers > or = 90% for each). Sensitivities for aneurysms (69-92%) and dissections overall (67-100%) were comparable, as they were in ascending and arch portions; descending dissection was better detected than descending aneurysm (two of four reviewers > or = 90% for ascending or arch aneurysm and for descending dissection); overall specificities (88-100 vs. 81-95%) and specificities in ascending, arch, and descending portions were also comparable (three to four of four reviewers > or = 90% for both in each portion; two of four reviewers > or = 90% for dissection overall). Each reviewer achieved > or = 70% diagnostic accuracy for TAD (one of four reviewers = 85%); accuracies for each category were comparable. Interpretation of standard MR images corrected all detection and most diagnostic (> or = 63%) errors. CONCLUSION: This initial experience with conventional TOF MRA for TAD evaluation is encouraging, but it indicates the potential for advancements in data acquisition and/or postprocessing.
Adolescent↗