Fast multi-planar gradient echo MR imaging: impact of variation in pulse sequence parameters on image quality and artifacts.

The purpose of this investigation was to quantitatively evaluate the practical impact of alteration of key imaging parameters on image quality and artifacts in fast multi-planar gradient echo (GRE) pulse sequences. These include multi-planar GRASS (MPGR) and fast multi-planar spoiled GRASS (FMPSPGR). We developed a composite phantom with different T(1) and T(2) values comprising the range of common biological tissues, which was also subjected to periodic motion in order to evaluate motion effects.

How to plan and perform a cardiac MR imaging examination.

Because of the enormous economic and social impact of cardiovascular disease in the United States there is a need for improved noninvasive diagnosis. Cardiac MR imaging isa versatile, comprehensive technique for assessing cardiac morphology and function. With an understanding of cardiac anatomy and physiology and MR imaging physical principles,cardiac MR imaging can be performed and can play an important role in patient management.

Fast T2-weighted MR imaging: impact of variation in pulse sequence parameters on image quality and artifacts.

The purpose of this study was to quantitatively evaluate in a phantom model the practical impact of alteration of key imaging parameters on image quality and artifacts for the most commonly used fast T(2)-weighted MR sequences. These include fast spin-echo (FSE), single shot fast spin-echo (SSFSE), and spin-echo echo-planar imaging (EPI) pulse sequences. We developed a composite phantom with different T1 and T2 values, which was evaluated while stationary as well as during periodic motion.

Manifestation of magic angle phenomenon: comparative study on effects of varying echo time and tendon orientation among various MR sequences.

The purpose of this study was to systematically investigate the effect of varying the echo time (TE) values and angle of the tendon to the main magnetic field (B(o)) upon the signal intensity observed with the magic angle phenomenon in tendons among most commonly used MR pulse sequences, including conventional spin echo (CSE), fast spin echo (FSE) and gradient echo (GRE) sequences. The intact bovine Achilles tendon was imaged using a clinical 1.5-T MR scanner.

Performing cardiac MR imaging: an overview.

Because of the enormous economic and social impact of cardiovascular disease in the United States, there is a need for improved noninvasive diagnosis. Cardiac MR imaging is a versatile, comprehensive technique for assessing cardiac morphology and function. With an understanding of cardiac anatomy and physiology as well as MR physical principles, cardiac MR imaging can be performed and play an important role in patient management.

T2-weighted echo planar MR imaging of the abdomen: optimization of imaging parameters.

Echo planar imaging (EPI) is an ultra-fast magnetic resonance (MR) imaging method that provides strong T2-weighted contrast, which is important for the detection and characterization of various abdominal abnormalities. However, EPI may be associated with significant artifacts. The prominence of these artifacts, as well as overall image quality, is dramatically impacted by selection of imaging parameters.

Comparative study of fast MR imaging: quantitative analysis on image quality and efficiency among various time frames and contrast behaviors.

The purpose of this study is to quantitatively compare the image quality and efficiency provided by widely available fast MR imaging pulse sequences. A composite phantom with various T1 and T2 values and subjected to periodic motion was imaged at 1.5 T.

Principles and applications of echo-planar imaging: a review for the general radiologist.

Echo-planar imaging is a very fast magnetic resonance (MR) imaging technique capable of acquiring an entire MR image in only a fraction of a second. In single-shot echo-planar imaging, all the spatial-encoding data of an image can be obtained after a single radio-frequency excitation. Multishot echo-planar imaging results in high-quality images comparable to conventional MR images.

A prospective assessment of breath-hold fast spin echo and inversion recovery fast spin echo techniques for detection and characterization of focal hepatic lesions.

The purpose of this study was to prospectively assess two breath-hold T(2)-weighted fast spin-echo sequences and two breath-hold inversion recovery fast spin-echo sequences to determine their relative ability to detect and characterize focal hepatic lesions. Fourteen patients with a total of nineteen proven focal hepatic lesions were imaged with two breath-hold T(2)-weighted (T2W) fast spin echo sequences (HASTE TE = 66 and HASTE TE = 120), two breath-hold inversion recovery fast spin echo sequences (IRFSE TE = 64 and IRFSE TE = 95), and a nonbreath-hold T(2)-weighted fast-spin echo sequence (FSE TE = 96-120). Contrast-to-noise ratios (CNRs) were measured for all proven lesions on all sequences.

Development and assessment of a radiology core curriculum in health care policy and practice.

Rationale And Objectives: The purpose of this study was to evaluate the feasibility of implementing a core curriculum in health policy and practice for radiology residents and fellows, to determine whether such a curriculum would be considered professionally valuable by participants, and to determine if the curriculum would influence participants' careers.

Materials And Methods: A core curriculum in health policy and practice was developed, involving 19 seminars presented over 5 weeks. Twelve faculty members presented comprehensive and integrated information relevant to current and future radiology practice.

MR imaging artifacts. Challenges and solutions.

A wide variety of artifacts is routinely encountered on MR images. This article reviews the cause, appearance, diagnostic effect, and available remedies for the artifacts that are most frequently observed on MR images and are of greatest clinical significance. Combined with routine preventive maintenance of imaging equipment, consistent quality control, and appropriate selection of imaging parameters, awareness of the manifestations of these artifacts will allow image quality and diagnostic interpretation to be optimized.

Hepatic T2-weighted MRI: a prospective comparison of sequences, including breath-hold, half-Fourier turbo spin echo (HASTE).

The purpose of this study was to quantitatively compare the hepatic contrast characteristics of conventional spin-echo (CSE) and fast spin-echo (FSE) sequences with breath-hold T2-weighted images acquired with half-Fourier turbo spin echo (HASTE). Forty-five patients were examined with a phased-array surface coil. Nineteen patients had focal hepatic lesions, including eight malignant tumors, 10 cavernous hemangiomas, and one hepatic adenoma.

Detection of coronary stenoses on source and projection images using three-dimensional MR angiography with retrospective respiratory gating: preliminary experience.

Objective: Our objective was to study the ability of three-dimensional MR angiography with retrospective respiratory gating to reveal stenoses in proximal coronary arteries on source and projection images.

Conclusion: Proximal coronary artery stenoses can be identified using three-dimensional MR angiography with retrospective respiratory gating, both with projection images and on source images alone. Reasons for missed lesions included collateral vessels and retrograde flow distal to complete occlusion and volume averaging of vessels with adjacent structures.

MR imaging of the shoulder. Imaging techniques, diagnostic pitfalls, and normal variants.

MR imaging techniques have been refined for evaluation of the shoulder. Available techniques and optimization of imaging parameters are reviewed. Anatomic variations, diagnostic pitfalls, and discrimination of pathologic entities from normal findings are discussed.

Interactive multiplanar reformation of conventional two-dimensional MR images.

In this report, we describe a new application for three-dimensional computer image processing that can provide for improved depiction of anatomical structures on routine nonvolumetric magnetic resonance (MR) examinations. The technique can be applied to standard two-dimensional MR images of the brain, spine, musculoskeletal system, and body including those obtained with relatively thick slices and with an intersection gap. This report demonstrates use of the reformation technique to establish retrospectively the symmetry in bilateral structures that were displayed out of alignment due to suboptimal patient positioning or patient motion during image acquisition and to improve the depiction of anatomical structures that were oriented out of the plane of original image acquisition.

MR diagnosis of rotator cuff tears of the shoulder: value of using T2-weighted fat-saturated images.

Objective: The purpose of this study was to compare the use of fat-saturated T2-weighted spin-echo MR imaging with that of conventional T2-weighted spin-echo MR imaging to detect full- and partial-thickness tears of the rotator cuff of the shoulder, using arthroscopy as the standard for the diagnosis.

Subjects And Methods: Forty-nine consecutive patients with shoulder pain who had both MR imaging and arthroscopy of their affected shoulders were studied. The study group consisted of 10 patients with full-thickness tears of the rotator cuff, 20 with partial-thickness tears of the rotator cuff, and 19 with intact rotator cuff tendons proved arthroscopically.

MR pitfalls and variants in the extrahepatic abdomen.

Although MR is used increasingly for abdominal imaging, there are many sources of potential diagnostic error. This article provides a review of the interpretive pitfalls, artifacts, and anatomic variations that are encountered most frequently when using MR imaging to evaluate extrahepatic abdominal structures.

Rapid abdominal MR imaging.

Rapid imaging techniques have assumed an important role in abdominal MR imaging. These methods not only decrease examination time but also improve the quality and diagnostic value of examination. This article discusses the most frequently used methods for decreasing imaging time for abdominal MR imaging and analyzes the relative advantages and disadvantages of each technique.

MR imaging evaluation of knee collateral ligaments and related injuries: comparison of T1-weighted, T2-weighted, and fat-saturated T2-weighted sequences--correlation with clinical findings.

The objectives of this study were to compare the ability of T1-weighted (T1W), proton density/T2-weighted (PD/T2W), and fat saturation (FS) PD/T2W magnetic resonance (MR) sequences for depiction of the knee collateral ligaments and related injuries, and to compare MR findings with clinical findings. Ten subjects with normal knee ligaments and 64 patients with suspected collateral ligament injuries underwent coronal T1W, PD/T2W, and FS PD/T2W imaging. Abnormalities ranged from edema surrounding the collateral ligaments (grade I) to complete disruption of ligamentous fibers (grade III).

Extension of vessels through hepatic neoplasms: MR and CT findings.

The undisturbed extension of vessels through an area of abnormal hepatic signal intensity on magnetic resonance (MR) images or abnormal attenuation on computed tomographic (CT) scans has been used as evidence of benign focal fatty infiltration and malignant hepatic neoplasms. Five cases are described in which either portal or hepatic veins extended through a hepatic lesion without evidence of appreciable mass effect, occlusion, or displacement of the vessels. These pathologically proved malignancies included hepatic lymphoma, metastatic melanoma, and metastatic adenocarcinoma.

Motion artifact as a pitfall in diagnosis of meniscal tear on gradient reoriented MRI of the knee.

Objective: Reorientation of the phase and frequency encoding gradients is frequently performed for knee MRI to improve visualization of the cruciate ligaments. This technique allows pulsation artifacts arising from the popliteal vessels to be redirected away from the intercondylar notch. The objective of this study was to evaluate the potential for this method to result in false-positive depictions of meniscal tears based on subtle patient motion.

T2-weighted MR imaging of the abdomen: fast spin-echo vs conventional spin-echo sequences.

Objective: The purpose of this study was to compare one optimized T2-weighted fast spin-echo sequence with one T2-weighted conventional spin-echo sequence to determine the impact of fast spin echo on image quality and diagnostic efficacy for evaluation of the abdomen.

Subjects And Methods: A total of 32 patients with 43 lesions involving various abdominal organs were examined. T2-weighted fast spin-echo (4000/119/4, echo train length = 16, matrix = 256 x 256) and T2-weighted conventional spin-echo (3400-3800/80/2, matrix = 128 x 256) images were compared qualitatively and quantitatively to determine whether the two types of images differed with respect to tissue contrast, conspicuousness of lesions, image quality, and artifacts.