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Biomedical subjects

S A Mirowitz

Publications and source records attributed to S A Mirowitz.

At least 37 records · Page 2Linked to original sources
PubMed1993

Evaluation of renal masses with contrast-enhanced rapid acquisition spin echo MR imaging.

To assess the use of dynamic contrast-enhanced rapid acquisition spin-echo (RASE) imaging for the detection and characterization of renal masses, we evaluated 18 patients with CT evidence of 67 renal masses. The masses included 58 simple cysts, 8 solid neoplasms, and 1 pseudotumor. Patients were examined with standard spin-echo (SE) pulse sequences including pre- and postcontrast T1-weighted images and noncontrast T2-weighted images as well as pre- and postcontrast RASE images. Each pulse sequence was reviewed individually and in a group with other pulse sequences by two blinded observers. The performance of contrast-enhanced RASE imaging either alone or in combination with a T2-weighted SE sequence resulted in improved diagnostic accuracy compared with unenhanced conventional SE and RASE sequences. The contrast-enhanced RASE sequence outperformed the contrast-enhanced T1-weighted SE sequence for one observer; similar diagnostic accuracy was achieved with the two examinations by the other observer. Combining the T2-weighted sequence with contrast-enhanced RASE images did not increase lesion detection but did increase the observers' confidence in making the diagnosis. Contrast-enhanced MR imaging resulted in significant improvement in the detection and characterization of renal lesions compared to unenhanced MR imaging.

Adult↗
PubMed1993

Evaluation of the prostate and prostatic carcinoma with gadolinium-enhanced endorectal coil MR imaging.

Thirteen patients who underwent subsequent radical prostatectomy for prostate cancer were studied with spin-density-T2-weighted and gadolinium-enhanced and unenhanced T1-weighted magnetic resonance (MR) imaging performed with an endorectal surface coil. With gadopentetate dimeglumine, the central gland showed inhomogeneous enhancement due to benign hyperplasia, whereas the peripheral zone demonstrated more uniform and less intense enhancement. With the T1-weighted sequence, depiction of the zonal anatomy, prostate capsule, surgical capsule, fibromuscular stroma, and periprostatic venous plexus was better with contrast enhancement, but these were best demonstrated on T2-weighted images. The trend was similar for prostatic tumor extent and capsular integrity. The seminal vesicles had a septal enhancement pattern and in several patients were best evaluated with enhanced T1-weighted images. These findings suggest that gadopentetate dimeglumine is not warranted for routine use in endorectal MR imaging of the prostate but may be useful for evaluation of the seminal vesicles in selected patients.

Aged↗
PubMed1993

Hematopoietic bone marrow within the proximal humeral epiphysis in normal adults: investigation with MR imaging.

The occurrence of hematopoietic bone marrow within the axial skeleton and meta-diaphyseal regions of long bones is well known. However, it has been generally accepted that hematopoietic marrow is not present within the epiphysis of long bones in normal adults. This study involved evaluation of marrow patterns in 96 patients presenting for shoulder magnetic resonance (MR) imaging examinations. Residual hematopoietic marrow was present within the proximal humeral metaphysis in 99% of patients and extended into the epiphysis in 62%. Epiphyseal hematopoietic marrow was more prominent in female subjects (P = .015) and showed correlation with prominence of hematopoietic marrow within the proximal humeral metaphysis (P = .01). The most characteristic pattern was a curvilinear distribution of hematopoietic marrow involving the subcortical region of the medial humeral head, though in some patients more centrally located patchy or globular regions of hematopoietic marrow were observed. These findings indicate that when signal intensity variations are observed within the epiphysis on MR images, the possibility of residual or reconverted hematopoietic marrow should be considered.

Adolescent↗
PubMed1993

MR and CT diagnosis of carcinoid heart disease.

This report describes findings present on magnetic resonance (MR) imaging and computed tomography (CT) in a patient with carcinoid heart disease. Major abnormalities included thickening and immobility of the tricuspid valve leaflets and disturbed flow patterns indicative of tricuspid stenosis and regurgitation demonstrated with cine MR. While echocardiography is usually the initial imaging modality in patients with carcinoid heart disease, other modalities such as MR and CT may provide correlative or supplemental information.

Carcinoid Heart Disease↗
PubMed1993

Fast scanning and fat-suppression MR imaging of musculoskeletal disorders.

Two of the most exciting areas of development in MR imaging in the past several years have been rapid imaging and fat-suppression techniques. This article reviews the most widely available techniques for performing rapid imaging and fat suppression and summarizes current clinical applications in musculoskeletal imaging.

Female↗
PubMed1992

Fibromuscular elements of the right atrium: pseudomass at MR imaging.

Results of 20 random cardiac spin-echo and cine gradient-echo magnetic resonance (MR) imaging examinations were reviewed for nodular and/or linear soft-tissue structures projecting from the right atrial wall. A nodular soft-tissue structure (mean diameter, 6 mm) isointense with myocardium was observed along the posterior atrial wall in 18 of 20 patients (90%). The structure extended between the orifices of the superior and inferior venae cavae. Linear strand-like projections originating from the structure coursed across the atrial chamber in 5 of 20 patients (25%). Similar findings were present in one patient who underwent cardiac surgery for a suspected atrial mass. The region of nodular thickening was shown histologically to represent myocyte hypertrophy and fibrosis. The nodular and linear structures correlated anatomically with the crista terminalis muscle bundle and Chiari network, respectively. These structures are frequently visualized on cardiac MR images, are of variable prominence, and may closely simulate the appearance of tumor or other cardiac masses in some patients. Awareness of the location and MR imaging features of these structures will help prevent misdiagnosis.

Aged↗
PubMed1992

Seminal vesicles: biopsy-related hemorrhage simulating tumor invasion at endorectal MR imaging.

The diagnosis of seminal vesicle invasion by prostatic carcinoma is based on observation of foci of relatively decreased signal intensity on T2-weighted magnetic resonance (MR) images. Similar findings were observed in the absence of tumor invasion in nine patients who had recently undergone prostatic needle biopsy. Noncorresponding foci of abnormally increased signal intensity were also present on T1-weighted images in eight patients. These signal intensity abnormalities were of variable location and extent, and usually did not follow the expected pattern of spread from the primary prostatic tumor site. Radical prostatectomy in all patients showed the seminal vesicles to be normal. Signal intensity patterns observed on MR images appear to represent hemorrhagic breakdown products related to prostatic needle biopsy, which may result in direct trauma to the seminal vesicles. Another potential mechanism is retrograde transport of blood products from the site of prostatic biopsy to the seminal vesicles via the ejaculatory ducts. Awareness of this phenomenon will assist in accurate interpretation of MR images for staging of prostate cancer.

Aged↗
PubMed1992

Intracranial lesion enhancement with gadolinium: T1-weighted spin-echo versus three-dimensional Fourier transform gradient-echo MR imaging.

The conspicuity of lesion enhancement with gadopentetate dimeglumine was evaluated subjectively and quantitatively through calculation of contrast-to-noise ratios (C/Ns) on T1-weighted three-dimensional (3D) Fourier transform (FT) gradient-echo (GRE) and two-dimensional (2D) FT spin-echo (SE) images of the brain in 406 consecutive patients. One hundred one enhancing intracranial lesions were present in 61 patients, including intra-(n = 76) and extraaxial (n = 25) processes of neoplastic (n = 68), infectious or inflammatory (n = 13), ischemic (n = 11), or vascular (n = 9) origin. Enhancement was apparent in all lesions on 2DFT SE and 3DFT GRE images, with similar subjective conspicuity in 86.8% (87 of 101) of lesions. Quantitative C/N measurements for 2DFT SE (mean, 17.6) and 3DFT GRE (mean, 17.2) imaging were not significantly different (P = .72). These findings, along with the other advantages of 3DFT GRE imaging, indicate that 3DFT GRE examinations are likely to play a major role in the performance of contrast-enhanced MR imaging of the brain.

Adult↗
PubMed1992

Basal ganglial signal intensity alterations: reversal after discontinuation of parenteral manganese administration.

The authors describe magnetic resonance (MR) imaging findings in a patient receiving long-term total parenteral nutrition (TPN) therapy in whom parenteral manganese administration was experimentally discontinued. MR imaging performed while the patient was receiving standard TPN solution demonstrated marked hyperintensity of the globi pallidi on T1-weighted images. Following cessation of parenteral manganese administration for 1 year, repeat MR imaging demonstrated regression of the abnormal signal intensity.

Basal Ganglia↗
PubMed1992

Ulnar collateral ligament injury in baseball pitchers: MR imaging evaluation.

The ulnar collateral ligament (UCL) provides stability to the medial aspect of the elbow during valgus stress. Trauma to this ligament may result from repetitive forceful throwing. Diagnosis of UCL injury has been based on clinical findings of medial joint pain and valgus instability, as direct imaging of this structure has not been available. Eleven baseball pitchers with clinical evidence of UCL injury were evaluated with magnetic resonance (MR) imaging. Surgical correlation was obtained in six patients, four of whom underwent UCL reconstruction. MR imaging findings in UCL injury included laxity, irregularity, poor definition, and increased signal intensity within and adjacent to the UCL. These findings reflect the presence of hemorrhage and/or edema within the UCL due to repeated microtears, which eventually lead to weakening and possible disruption of the UCL. Optimization of spatial resolution, signal-to-noise ratio, and other technical factors is critical for evaluation of the UCL due to its small size. MR imaging is useful in documenting the presence and severity of injury to the UCL and in distinguishing this entity from other causes of elbow pain.

Adolescent↗
PubMed1992

Gadopentetate dimeglumine-enhanced MR imaging of the postoperative lumbar spine: comparison of fat-suppressed and conventional T1-weighted images.

OBJECTIVE: Gadopentetate dimeglumine-enhanced T1-weighted MR imaging has been used to distinguish epidural fibrosis from recurrent disk herniation in the postoperative lumbar spine. Potential interpretative difficulties relate to detection of subtle contrast enhancement and distinction of enhanced tissue from surrounding epidural fat. The objective of this study was to evaluate the utility of fat-suppressed T1-weighted imaging in improving the depiction of postoperative abnormalities. SUBJECTS AND METHODS: Forty-one patients with recurrent signs and symptoms after previous laminectomy and diskectomy were examined with conventional and fat-suppressed T1-weighted imaging before and after IV administration of gadopentetate dimeglumine. MR images were analyzed for the presence or absence of an epidural soft-tissue mass located anterior and/or lateral to the thecal sac. When such masses were identified, their contrast enhancement behavior was characterized according to the volume, intensity, and pattern of enhancement. Epidural fibrosis was diagnosed by using established MR imaging criteria. In patients with evidence of recurrent disk herniation, diagnosis was based on surgery in six patients and on MR imaging findings in the remainder. RESULTS: Soft-tissue masses were present at 32 of the 43 levels operated on, representing epidural fibrosis (n = 21) or disk herniation (n = 11). Fat suppression improved depiction of contrast enhancement associated with sites of epidural fibrosis. The extent, intensity, and homogeneity of enhancement was greater with fat suppression than with conventional imaging, although the ability to distinguish epidural fibrosis from recurrent disk herniation was not improved. CONCLUSION: Use of the fat-suppression technique results in increased relative intensity and homogeneity of contrast enhancement associated with sites of epidural fibrosis. However, it does not result in significant improvement in the ability to differentiate fibrotic tissue from recurrent disk herniation. Fat suppression does not appear to be indicated for routine use in imaging of the postoperative lumbar spine, but may be useful as a problem-solving tool in selected patients.

Adult↗
PubMed1991

Evaluation of congenital heart disease by three-dimensional magnetic resonance imaging.

This study was undertaken to compare electrocardiographically gated magnetic resonance imaging (MRI) to established imaging modalities in the detection of complex intra- and extracardiac morphologic defects. Twenty-three patients with congenital cardiac abnormalities were imaged by four methods: cardiac catheterization, echocardiography, two-dimensional (2D) transaxial MRI, and three-dimensional (3D) MRI surface reconstruction. Observers with experience in congenital cardiac disease diagnosis (two for echo, one for catheterization, two for 2D MR, and three for 3D MR) evaluated the images in a blinded fashion, and the results were analyzed with receiver operating characteristic (ROC) analysis. Overall, cardiac catheterization had the best diagnostic performance. The diagnostic value of routine 2D cardiac MR images and 3D MR reconstruction images were similar to that of echocardiography. All of the modalities performed poorly in the diagnosis of extracardiac defects and atrial septal defects.

Cardiac Catheterization↗
PubMed1991

Dynamic gadolinium-enhanced rapid acquisition spin-echo MR imaging of the liver.

Rapid acquisition spin-echo (RASE) magnetic resonance (MR) imaging allows for coverage of the entire liver with highly T1-weighted SE images during a single 23-second breath-holding period. The RASE sequence was implemented in conjunction with rapid intravenous injection of gadopentetate dimeglumine to enable performance of dynamic contrast material-enhanced MR imaging of the liver. Prospective evaluation of 24 patients with 62 liver lesions 1 cm or greater in diameter was performed. Images obtained with RASE were devoid of respiratory-related ghost artifacts or edge blurring. The dynamic contrast-enhanced RASE technique resulted in contrast-to-noise and contrast-to-artifact values and time efficiency measures significantly greater (P less than .05) than those obtained with use of conventional T1- and T2-weighted pulse sequences, indicating a higher likelihood for lesion detectability. Lesion conspicuity was maximal during or immediately following bolus administration of gadopentetate dimeglumine, with lesions often becoming obscured at delayed postcontrast imaging.

Adult↗
PubMed1991

Dynamic gadolinium-enhanced MR imaging of the spleen: normal enhancement patterns and evaluation of splenic lesions.

The authors studied the ability to improve detection of splenic lesions during suspended respiration with dynamic gadolinium-enhanced T1-weighted spin-echo magnetic resonance (MR) imaging. In the first phase of the study, normal splenic contrast material enhancement patterns were assessed in 10 control patients without splenic lesions. A heterogeneous signal intensity pattern was observed in 11 patients with splenic lesions during bolus injection of gadopentetate dimeglumine, with conversion to homogeneous enhancement 1 minute later. Mean splenic enhancement was 321% during bolus injection, with a rapid return toward baseline signal intensity thereafter. In the second phase, evaluation of 18 splenic lesions detected with contrast-enhanced computed tomography in 11 patients revealed that dynamic gadolinium-enhanced MR pulse sequences significantly improved lesion conspicuity and detectability compared with conventional T1-and T2-weighted pulse sequences. Contrast-to-artifact ratio measurements were 0.5, 3.7, and 9.3 for conventional T1-weighted, T2-weighted, and dynamic gadolinium-enhanced MR images, respectively.

Adult↗