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Biomedical subjects

S A Mirowitz

Publications and source records attributed to S A Mirowitz.

At least 19 recordsLinked to original sources
PubMed2000

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. Both IRFSE sequences and the HASTE sequence with TE = 66 showed an improvement in lesion-liver and liver-spleen CNRs compared to the nonbreath-hold T2W sequence. The mean difference in CNR between benign and malignant lesions was largest for the HASTE TE = 120 sequence. These preliminary results suggest that a breath-hold IRFSE sequence (TE = 64 or 95) has an equal ability to detect focal hepatic lesions as a nonbreath-hold T2W FSE sequence (TE = 96-120). The HASTE TE = 120 showed the greatest ability to discriminate between benign and malignant lesions.

Adult↗
PubMed2000

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. Topic clusters included health care structure and payment, technology and health services, radiology practice management, and career issues. Classroom teaching was supplemented by a course syllabus and resource library. Participants were surveyed following each seminar and at the conclusion of the curriculum. RESULTS: Participants described their baseline knowledge of each topic as weak. As a result of the curriculum, self-described knowledge ratings increased considerably. Interest in curriculum topics and perception of their importance and relevance to radiology practice increased. Of respondents, 84% (26 of 31) described the curriculum as having very good or excellent educational value. All respondents indicated that the curriculum should be repeated in the future, 42% (13 of 31) indicated that the curriculum motivated them to pursue further related education, and 61% (19 of 31) developed interest in personal involvement in administrative issues and radiology organizations. CONCLUSION: A core curriculum in health policy and practice was successfully integrated into radiology training. The curriculum resulted in increased knowledge, interest, and perceived importance of medical management issues by residents and fellows and stimulated their interest in pursuing further management education and involvement in radiology administration and organizations.

Attitude of Health Personnel↗
PubMed1999

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.

Artifacts↗
PubMed1998

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. Causes of false-positive interpretations included small foci of decreased signal intensity distal to complete occlusion, partial volume effects on individual partitions, and regions of distal vessels leaving the imaging plane.

Aged↗
PubMed1995

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. All patients had T1-weighted, conventional T2-weighted, and fat-saturated T2-weighted MR images obtained in a plane slightly oblique to the coronal plane along the long axis of the supraspinous tendon. The images were divided into two sets, one including both T1-weighted and conventional T2-weighted images, the other including T1-weighted and fat-saturated T2-weighted images. Two musculoskeletal radiologists reviewed each set of MR images in a blinded fashion. The reviewers were asked to decide whether the rotator cuff showed a full-thickness tear, a partial-thickness tear, or no tear on each set of images. In the case of partial-thickness tears, the reviewers were asked to indicate which surface (bursal or joint) of the rotator cuff was affected. These data were correlated with the arthroscopic findings and with each other using McNemar and kappa analysis. RESULTS: Detection of full-thickness tears was excellent for both reviewers using either imaging technique. However, when the fat-saturated technique was used, the sensitivity increased significantly, from 80% to 100%. Detection of partial-thickness tears was poor with conventional spin-echo MR imaging (15%). Although significantly improved when fat saturation was used (35%), detection rates were still lower than rates reported in the literature. Identification of the torn surface of the rotator cuff was correct in 50% of cases in which partial-thickness tears were successfully identified. Fat saturation decreased the specificity of identification of both partial and full-thickness tears of the rotator cuff but significantly increased the specificity with which intact rotator cuffs were identified. CONCLUSION: Use of the fat-saturation technique improved detection of both full-thickness and partial-thickness tears of the rotator cuff on MR images compared with standard spin-echo imaging techniques. Despite this improvement, detection of partial-thickness tears was poor with both techniques. Furthermore, correct identification of which surface of the rotator cuff was torn in patients with partial tears was nearly random.

Adult↗
PubMed1995

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.

Abdomen↗
PubMed1995

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.

Abdomen↗
PubMed1994

Evaluation of fat saturation technique for T2-weighted endorectal coil MRI of the prostate.

The use of fat suppression has been found to improve tissue contrast and artifact control for performance of body coil MR imaging of the pelvis. The objective of this study was to evaluate whether use of fat suppression confers similar advantages when endorectal coil MR examinations are performed for staging of prostate cancer. Sixty consecutive patients were evaluated with conventional T1-weighted (TR 600, TE 20) and conventional and fat saturation proton density-/T2-weighted (TR 2500, TE 35/80) sequences. Thirteen of 60 patients underwent subsequent radical prostatectomy and constituted the study group for which conventional and fat suppressed long TR images were directly compared by three reviewers. Criteria assessed included the relative ability of each sequence to demonstrate zonal distinction, periprostatic venous plexus, fibromuscular stroma, capsule definition, seminal vesicle architecture, tumor conspicuity, capsular penetration and/or seminal vesicle tumor invasion, artifact control, and overall image quality. There was no statistically significant improvement in factors relating to image quality with use of fat saturation. In addition, depiction of the anatomic and pathologic features listed above was not significantly improved for fat-suppressed as compared with conventional endorectal coil images. It is concluded that fat saturation does not result in significant improvement over conventional T2-weighted images in endorectal MR imaging of the prostate.

Humans↗
PubMed1994

Evaluation of fat saturation technique for T2-weighted MR imaging of the spine.

The objective of this study was to evaluate the use of fat saturation for performance of T2-weighted imaging of the spine. Eighteen consecutive patients underwent MR imaging of the cervical (n = 7) or lumbar (n = 11) spine with proton density/T2-weighted sequences (TR 2200 ms, TE 30/80 ms) performed with and without fat saturation. Quantitative and qualitative analysis of images was conducted to compare tissue contrast, myelographic effect, presence of artifacts, and ability to delineate important anatomic structures on conventional and fat suppressed sequences. Images obtained with fat saturation demonstrated improved myelographic effect and increased contrast between vertebral body and disk, and between CSF and nerve roots/spinal cord. Image quality and most artifacts were equal on both sequences, though fat suppressed images had reduced image uniformity. Quantitative measurements of tissue contrast indicated improved contrast between vertebral bodies and CSF, disk, and spinal cord/nerve roots on fat saturation images.

Adult↗
PubMed1994

Chemical shift misregistration artifact: increased conspicuity following intravenous administration of gadopentetate dimeglumine.

We have observed increased conspicuity of chemical shift misregistration artifact (CSMA) associated with enhancing structures on MR images after the intravenous administration of gadopentetate dimeglumine compared with corresponding unenhanced images. In this study, we investigate the influence of gadopentetate dimeglumine administration on the conspicuity of CSMA in MR imaging of the kidneys. Nine gadopentetate-enhanced and unenhanced T1-weighted images of the kidneys were evaluated in a side-by-side fashion for the conspicuity of both the high and low signal intensity (SI) components of CSMA. A phantom study of saline in a bath of oil and increasing concentrations of gadopentetate dimeglumine in a bath of oil was performed. There was increased conspicuity of both the high and low SI components of CSMA in gadopentetate-enhanced images compared with unenhanced images in all study cases and in the phantom samples containing gadopentetate compared with the saline control. In conclusion, the administration of gadopentetate dimeglumine results in increased conspicuity of CSMA on MR images of the kidneys.

Aged↗
PubMed1994

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.

Aged↗
PubMed1994

MR imaging of the normal meninges: comparison of contrast-enhancement patterns on 3D gradient-echo and spin-echo images.

OBJECTIVE: The purpose of this study was to determine the enhancement pattern of the normal meninges on T1-weighted three-dimensional Fourier transform gradient-echo (3DGE) MR images and to compare this pattern with that observed on conventional two-dimensional Fourier transform spin-echo (2DSE) images. This will serve as a basis for comparison when cases of suspected meningeal pathology are evaluated. SUBJECTS AND METHODS: The appearance of the normal meninges after administration of gadopentetate dimeglumine was evaluated on 2DSE and 3DGE images in 69 patients who had no known or suspected meningeal abnormality. The total percentage of meningeal surface area that underwent contrast enhancement and the continuity of meningeal enhancement were evaluated at four anatomic levels. RESULTS: In most patients, 2DSE images showed short segments (i.e., < 3 cm) of meningeal enhancement, with enhancement of less than 50% of total meningeal surface area. However, enhancement of 76-100% of total meningeal surface area was routinely observed on 3DGE images, with long segments (i.e., > 3 cm) or continuous patterns most frequently observed. The differences between 2DSE and 3DGE sequences were statistically significant for all regions that were assessed. CONCLUSION: Continuous meningeal enhancement or enhancement of long segments of normal meninges is routinely observed on contrast-enhanced 3DGE images; this appearance differs from those of enhanced 2DSE images and should not be interpreted as abnormal.

Adult↗
PubMed1994

MR imaging of bone marrow lesions: relative conspicuousness on T1-weighted, fat-suppressed T2-weighted, and STIR images.

OBJECTIVE: Fat-saturation pulse sequences offer important potential advantages for depiction of bone marrow lesions on MR images. The objectives of this study were to evaluate the relative conspicuousness of bone marrow lesions on images obtained by using two of the most widely available fat-suppression techniques, short-TI inversion recovery (STIR) and fat-saturation T2-weighted imaging, and to analyze the effect of these methods on image quality. In addition, we sought to determine if either or both of these sequences provide significant advantages relative to conventional T1-weighted spin-echo images for the evaluation of bone marrow lesions. SUBJECTS AND METHODS: T1-weighted (600/15 [TR/TE]), STIR (2500/20/160 [TR/TE/TI]), and fat-saturation T2-weighted (2500/20-70) MR images were obtained with a 1.5-T system in 34 consecutive patients with suspected bone marrow lesions. The conspicuousness of 36 lesions was evaluated subjectively by three radiologists, who also evaluated the MR images for how well they showed margination and extent of the lesion, image uniformity, motion artifacts, and overall image quality. In addition, lesion contrast on these sequences was compared quantitatively by using percentage contrast measurements. RESULTS: Lesions were qualitatively equally conspicuous with all four pulse sequences. Quantitative measurements indicated that lesions were more conspicuous on fat-saturation T2-weighted and STIR images than on T1-weighted images (p < .001). Differences between the first two sequences were not significant. Factors related to image quality, including reduction in motion artifacts and image uniformity, were generally superior on T1-weighted images. CONCLUSION: T1-weighted, fat-saturation T2-weighted, and STIR sequences all provide a high degree of sensitivity for depiction of most types of bone marrow abnormalities. Although the conspicuousness of lesions is similar on fat-saturation T2-weighted and STIR images, the former sequence has several practical advantages, including acquisition of more slices per unit time and improved tissue specificity. The combination of T1-weighted and either fat-saturation T2-weighted or STIR images is highly effective for the evaluation of bone marrow lesions.

Adolescent↗
PubMed1994

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. RESULTS: The signal intensity of all abdominal structures (except gallbladder and fat) was significantly lower on fast spin-echo images than on conventional spin-echo images. Qualitative liver-to-spleen contrast was significantly reduced on fast spin-echo images, whereas quantitative liver-to-spleen contrast was not significantly different. Blurring of anatomic structures, vascular pulsation, and chemical-shift misregistration artifacts were significantly reduced on fast spin-echo images. The qualitative conspicuousness and contrast-to-noise ratio for all lesions evaluated together were not significantly different (p = .5 and p = .069, respectively) on fast spin-echo vs conventional spin-echo images. However, qualitative conspicuousness and contrast-to-noise ratio of solid lesions were significantly reduced on fast spin-echo images (p = .022 and p = .01, respectively). The contrast-to-noise ratio of cystic lesions was significantly better (p = .002) on fast spin-echo images than on conventional spin-echo images. CONCLUSION: Although the fast spin-echo protocol used in this study provides better image quality and contrast-to-noise ratio for cystic abdominal lesions than does conventional spin echo, the qualitative conspicuousness and contrast-to-noise ratio of solid abdominal lesions are decreased. Fast spin echo provides high-quality images with fewer artifacts in significantly less time than is possible with conventional spin-echo images. Further evaluation is necessary to determine the optimal protocol for T2-weighted fast spin-echo MR imaging of the abdomen.

Abdominal Neoplasms↗
PubMed1993

Contrast enhancement of the gastrointestinal tract on MR images using intravenous gadolinium-DTPA.

Gadopentetate dimeglumine was administered intravenously to 16 patients undergoing abdominal magnetic resonance (MR) imaging. T1-weighted and fat-suppressed T1-weighted images were acquired before and after intravenous administration of 0.1 mmol/kg gadopentetate dimeglumine. The stomach, small bowel, and colon were analyzed regarding the presence and relative intensity of contrast enhancement. Diffuse enhancement of the gastrointestinal tract wall was observed in all patients following contrast material administration. Such enhancement was most conspicuous on fat-suppressed T1-weighted images. Quantitative measurements indicated that the wall of the gastrointestinal tract enhanced approximately 100% with gadopentetate dimeglumine. This study demonstrates that enhancement of the normal gastrointestinal tract occurs routinely when intravenous gadopentetate dimeglumine is administered, and such enhancement should not be considered indicative of gastrointestinal pathology. Furthermore, it suggests the potential utility for using intravenous rather than orally administered contrast agents to provide enhancement of the gastrointestinal tract on MR images.

Adult↗