To determine the prevalence of cardiac abnormalities in patients with human immunodeficiency virus (HIV) infection, two-dimensional Doppler echocardiography was performed on 70 consecutive patients with HIV infection, including 51 with acquired immunodeficiency syndrome (AIDS), 13 with AIDS-related complex and 6 with asymptomatic HIV infection. Of the 70 patients, 36% were hospitalized and 64% were ambulatory at the time of evaluation. The average age was 37 years; 93% were homosexual men. Echocardiographic findings included dilated cardiomyopathy in eight patients (11%), pericardial effusions in seven patients (10%) (one with impending tamponade), pleural effusion in four patients (6%) and mediastinal mass in one patient (1%). Among the 25 hospitalized patients, echocardiographic abnormalities were noted in 16 (64%), whereas among the 45 ambulatory patients, the only abnormality noted was mitral valve prolapse in 3 patients (7%) (p less than 0.0001). Dilated cardiomyopathy was the only echocardiographic lesion more common in the 25 hospitalized patients than in 20 hospitalized control patients with acute leukemia. Symptoms of congestive heart failure responded to conventional therapy. Cardiac lesions were associated with active Pneumocystis carinii pneumonia and low T helper lymphocyte counts. Dilated cardiomyopathy of unknown origin may be more common than was previously recognized in hospitalized, acutely ill patients with AIDS, but is uncommon in ambulatory patients with HIV infection. Echocardiography should be considered in the evaluation of dyspnea in hospitalized patients with HIV infection, especially those with dyspnea that is out of proportion to the degree of pulmonary disease.
A technique for reformatting multislice magnetic resonance images into arbitrary oblique planes has been developed and implemented on a Toshiba MRT-36 (formerly Diasonics MT/S) imaging system (South San Francisco, CA). This method is designed to allow the user to easily define a new plane by marking with a cursor features of interest on two or three different image levels. These features ara combined in the resulting oblique image. The reformatted image can have arbitrary angulation and is created with a pixel dimension equivalent to the original data set. Resolution ranges from the original in-plana resolution to the slice thickness, depending on angulation. An improvement in signal-to-noise ratio results from the effective averaging performed by interpolation. This method is optimally used to correct for small variations in alignment, such as the positioning of the intervertebral disks. It can also be used to generate reformatted images at many different angles from a single multislice data set. This method has been applied to the particular problem of improving the presentation of coronary arterias on a conventional set of multislice spin-echo cardiac images by increasing the visible length of individual coronary segments. 9 1990 by W.B. Saunders Company.KEY WORDS: magnetic resonance imaging, image processing, computers.
T HE INTRINSIC CONTRAST betweenflowing blood and solid tissue that exists with magnetic resonance imaging (MRI) make it an attractive means of studying vascular anatomy without the need for contrast media. New methods use time-of-flight effects of moving blood or take advantage of velocity-dependent phase changes to encode information into the image. The prospect that these techniques might be extended to image the coronary arteries has many researchers eagerly investigating imaging strategies that may provide diagnostic information about coronary disease. 1' 2 This turns out to be a much more challenging problem because of the nature of coronary anatomy, in particular the narrow dimension and tortuousness of the vessels, the pulsatility of the flow, the motion of the heart, and its underlying blood pools. Low spatial resolution and the tomographic imaging format of MRI compared with angiography make the imaging of coronary vessels particularly difficult. Conventional two-dimensional Fourier transform (2DFT) spin-echo images are acquired in multislice format using a technique of selective excitation for slice isolation and phase and frequency encoding for in-plane spatial differentiation. This method produces images with slice thicknesses up to 10 times the in-plane pixel dimension. Our cardiac imaging sequence is a multislice, multiphase spin-echo technique that generates transaxial images with 10-mm slice thickness, 256 x 256-pixel matrix, and 0.95-mm in-plane resolution. Noninterleaved contiguous slices are acquired with no slice gap. Images at five phases of the cardiac cycle are collected using electrocardiographic gating and triggering on the R wave. An echo-delay time (TE) value of 30 ...
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