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Biomedical subjects

W B Gefter

Publications and source records attributed to W B Gefter.

At least 73 records · Page 4Linked to original sources
PubMed1990

Pulmonary vascular cine MR imaging: a noninvasive approach to dynamic imaging of the pulmonary circulation.

Cine gradient-recalled magnetic resonance (MR) imaging, which has flow sensitivity and high temporal resolution, may potentially yield both morphologic and dynamic flow-related information in the pulmonary vasculature. The authors used this modality to evaluate pulmonary vessels in 12 healthy subjects and in 14 patients with a variety of cardiopulmonary disorders. Normal pulmonary arteries and veins were characterized by distinctive signal intensity and diameter variations as well as motion of the vessels during the cardiac cycle. Patients with pulmonary arterial hypertension demonstrated loss of the normal pulsatile systolic increase and diastolic decline in velocity-related signal intensity and in diameter of the proximal pulmonary arteries. Disorders of pulmonary venous signal and diameter profiles during the cardiac cycle, which show a characteristic biphasic pattern in healthy subjects, were identified in five patients with mitral valvular disease. These initial results indicate that cine MR imaging techniques hold promise in the evaluation of pathophysiologic conditions in the pulmonary circulation.

Adult↗
PubMed1989

Pulmonary vasculature: high-resolution MR imaging. Work in progress.

High-resolution magnetic resonance (MR) imaging of the lung has the potential to depict not only small pulmonary vascular structures but also pulmonary blood flow. Five healthy volunteers were examined to assess the effects of (a) the use of two 5-inch surface coils located on the anterior and posterior chest walls, with a 24-cm field of view and a matrix of 256 X 256; (b) spin-echo acquisition with electrocardiographic (ECG) gating during systole or diastole; and (c) gradient recalled acquisition in a steady state (GRASS) with breath holding. These techniques yielded images showing small peripheral pulmonary vascular structures. Most subsegmental vessels and sixth- and seventh-order branches could be traced, especially near the coils. GRASS images obtained with dual surface coils and breath holding depicted fifth- and sixth-order branches. Preliminary results indicated that small pulmonary vessels can be imaged with MR with a combination of high-resolution techniques and ECG gating in diastole. The sensitivity and reproducibility of these techniques in demonstrating pulmonary vasculature warrant further investigation.

Adult↗
PubMed1989

Prostatic carcinoma and benign prostatic hyperplasia: correlation of high-resolution MR and histopathologic findings.

High-resolution magnetic resonance (MR) imaging of 24 fresh radical prostatectomy specimens was performed on an experimental 1.9-T system. Direct correlation between the findings in 7-micron-thick macrosections and their corresponding MR images was possible. Fourteen patients had macroscopic evidence of cancer. In all 14 cases, the carcinoma nodules appeared as areas of low signal intensity on images obtained with a repetition time of 2,500 msec and an echo time of 80 msec. Ten of 14 nodules had well-defined margins and consisted of densely packed glandular elements, which displaced the surrounding normal glandular material of higher signal intensity. Ten specimens displayed benign prostatic hyperplasia (BPH). The MR characteristics of this entity were quite variable but relatively predictable, depending on the distribution and size of the glandular elements, as well as the composition of the surrounding stroma. In BPH, the changes began in the central portion of the gland. The areas of highest signal intensity corresponded to dilated glandular elements (cystic ectasia), while the areas of lowest signal intensity corresponded to collagen (scar) and fibromuscular stroma. Nodules of mixed glandular BPH and fibromuscular BPH were found to have signal intensities similar to those of well-differentiated nodules of prostatic adenocarcinoma.

Aged↗
PubMed1988

Chronic traumatic diaphragmatic hernia: the significance of pleural effusion.

Five patients with chronic traumatic diaphragmatic hernia presented with symptoms of acute intestinal obstruction and unilateral pleural effusion. In each case, infarcted herniated abdominal structures were found at surgery. The presence of an ipsilateral pleural effusion is an important radiographic sign, which may indicate strangulation in patients with chronic traumatic diaphragmatic hernia.

Adult↗
PubMed1988

Clinical evaluation of a medical image management system for chest images.

The clinical efficacy and physicians' assessment of a medical image management system (MIMS) for chest images that involved the medical intensive care unit (MICU) and the radiology department were evaluated. A token-passing fiber-optic network was implemented to connect display stations in the MICU and in the chest reading area in the radiology department with a laser film digitizer and an archiving system. To study the clinical efficacy of this system, blocks of 8 weeks during which portable chest images were digitized and immediately made available in the MICU were alternated with blocks of 8 weeks during which film images only were available. Approximately 3000 portable chest examinations were tracked; patients were entered into the study at a rate of 65 per month. Data on time intervals associated with the examination process were collected from MICU physicians, radiologists, radiographers, and film librarians. The time from the completion of an examination to the time an action was taken that was based on radiographic findings showed significant reductions during the digital periods for certain actions. For example, the time to begin drug therapy decreased from a mean of 4.7 hr when films were viewed to a mean of 3.3 hr when digital images were viewed. In conclusion, if prompt action by the MICU physician improves a patient's outcome, a positive effect on patient care will result from the immediate availability of radiographic images.

Computer Systems↗
PubMed1988

Meniscal and ganglion cysts of the knee: MR evaluation.

Meniscal and ganglion cysts frequently present as palpable masses of the knee but occur at different locations than do popliteal cysts. Meniscal cysts also may be discovered incidentally on studies performed for suspected internal derangement. Sixteen cystic lesions of the knee were evaluated with MR, including 11 meniscal cysts and five ganglion cysts. Scans were performed at 1.5 T by using a transmit/receive extremity coil or a receive-only surface coil. Standard spin-echo imaging, including at least one long-TR/asymmetric-TE sequence, was performed in all cases. In six patients, gradient-echo, reduced flip-angle sequences also were done. All meniscal cysts (but none of the ganglion cysts) were associated with horizontal meniscal tears. Cysts were visualized best on the long-TR/TE images; meniscal tears were seen best on the short-TR/TE and long-TR/short-TE images. Meniscal tears and cysts were also seen well on the fast-scanning sequences. Septations were noted in four meniscal cysts and in four ganglion cysts on the long-TR/TE images. Long-TR/TE images were also useful in showing the relationship between the cyst and joint capsule in three of the ganglion cysts. MR imaging is an effective, noninvasive method for evaluating cystic lesions of the knee. Meniscal cysts are always associated with underlying horizontal meniscal tears, which can be detected with MR. Ganglion cysts are not associated with meniscal tears, but may have connections to the joint capsule, which can be detected with MR.

Humans↗
PubMed1988

Issues and controversies in the plain-film diagnosis of asbestos-related disorders in the chest.

This article reviews the chest radiographic manifestations of asbestos exposure. While the chest radiograph (CXR) is a highly valuable tool in the evaluation of asbestos-related disease, there are ongoing controversies regarding the sensitivity and specificity of the plain film in diagnosing asbestos-related disorders. Autopsy series indicate that at least 60% of pleural plaques may be overlooked. Conversely, such series indicate that up to 20% of plaques are falsely diagnosed. The significance of visceral pleural thickening and the definition and positive predictive value of diffuse pleural thickening as they relate to asbestos exposure are unresolved issues. Data suggest that the CXR may fail to reflect significant asbestosis in 10% to 20% of cases. On the other hand, the presence of overlying pleural abnormalities as well as technical factors may contribute to overreading of interstitial disease. Data on the rate of false positive readings for asbestosis are limited. Considered alone, the CXR can support but not specifically establish nor exclude the diagnosis of asbestosis. In practice, an ILO grade of less than 1/0 implies that the diagnosis is unlikely. A constellation of positive CXR findings may increase specificity, although the diagnosis rests on a combination of multiple clinical criteria.

Asbestos↗
PubMed1988

MRI of the upper aerodigestive tract and neck.

The application of new technology has improved the ability of MR to image the upper aerodigestive tract and neck. Improved resolution along with inherent high tissue contrast and multiplanar capability now allow clear definition of detailed anatomic and pathologic tissue planes. MR currently rivals other imaging modalities in this region. At present, it is often better in demonstrating the depth of tumor infiltration and the presence of nodal metastasis. Initial studies also suggest that MR can effectively image postoperative sites and discriminate chronic fibrosis from recurrent tumor. Localization of abnormal parathyroid glands, particularly for re-exploration, is a promising technique. If the present limitations are recognized, such as identification of soft tissue calcification, MR can play an important role in the evaluation of the face and neck. With additional investigation and continued technologic improvements it is likely that this role will continue to increase.

Head and Neck Neoplasms↗
PubMed1988

Chest applications of magnetic resonance imaging: an update.

Accumulated experience with MR applications in the chest has helped to define its role relative to other modalities. Technical advances improving image quality, newer fast scans, and cine methods are expanding the information available from MR. This discussion reviews the useful applications and limitations of MR in evaluating thoracic disorders. Physicians should be knowledgeable and selective in their utilization of this modality.

Aortic Dissection↗
PubMed1987

Magnetic resonance imaging of Morgagni hernia.

A case of a Morgagni hernia is demonstrated by magnetic resonance imaging (MRI). The correct diagnosis was facilitated by the ability to image directly the anteromedial diaphragmatic defect in the coronal and sagittal planes. The findings from MRI, computed tomography, and radiographic studies are correlated.

Aged↗
PubMed1987

Abnormal parathyroid glands: high-resolution MR imaging.

High-resolution magnetic resonance (MR) images of the neck were obtained in 23 patients with hyperparathyroidism. Surgical confirmation was available in all cases. MR imaging allowed accurate localization of 14 of 17 parathyroid adenomas, two of two parathyroid carcinomas, and five of eight hyperplastic glands, the latter from three patients. MR depicted nine of 11 (82%) abnormal glands that were 0.5-1.0 cm in size and 12 of 14 (85.7%) glands larger than 1 cm in diameter. In all but one case, abnormal glands had signal intensity greater than or equal to that of fat on spin-echo images with long repetition time and echo time. Parathyroid adenomas, carcinomas, and hyperplasia could not be distinguished from each other. The overall sensitivity and specificity of MR imaging in the detection of parathyroid abnormalities was 77.8% and 95.4% respectively, resulting in an accuracy of 90.2%. This compares favorably with other imaging modalities.

Adenoma↗
PubMed1987

Prostatic disorders: MR imaging at 1.5 T.

Pelvic magnetic resonance (MR) images obtained at 1.5 T of 31 men with known genitourinary disease were reviewed retrospectively. In most, peripheral and central prostatic zones could be seen on axial images obtained with long repetition times/echo times (TRs/TEs). The prostate had no specific signal intensity that enabled differentiation between benign and malignant changes. Each patient with known extracapsular prostatic carcinoma had a peripheral zone defect--1 cm or greater in diameter with ill-defined borders and relatively lower signal intensity than that of the remainder of the peripheral zone--that correlated with the site of clinical-pathologic involvement. Correlation of a peripheral zone defect on long TR/TE images as a sign for extracapsular spread of prostatic cancer was 100% sensitive, yet 54% specific, with excellent interobserver agreement. Stage A2 and B1 prostatic carcinoma was not detected. Benign prostatic hyperplasia was seen as centrally located proliferation and nodularity, usually with discrete margins and a wide spectrum of low- to high-signal-intensity features. MR imaging may have a role in differentiating between intracapsular and extracapsular prostatic carcinoma.

Adult↗
PubMed1987

Normal prostate and adjacent structures: MR imaging at 1.5 T.

Pelvic magnetic resonance images obtained at 1.5 T of 29 male patients with no known genitourinary tract disease were retrospectively reviewed. Normal anatomic features of the prostate and its adjacent structures were studied with spin echo techniques with short and long repetition times/echo times (TR/TE). Long TR/TE (T2-weighted) images routinely showed differentiation of peripheral and central prostatic zones, as well as a separate periprostatic venous plexus. Guidelines were developed to optimize imaging of the relationship of the prostate to adjacent structures.

Adult↗
PubMed1987

Thyroid imaging with high-field-strength surface-coil MR.

Magnetic resonance (MR) imaging of the thyroid was performed with a 1.5-T system and local receiver coil in 19 "healthy" subjects and 34 patients with various focal and diffuse thyroid disorders. The normal gland was typically homogeneous with increased intensity relative to that of muscle on images obtained with long repetition times (TRs) and long echo times (TEs). Adjacent structures in the neck and upper mediastinum were well displayed. Thyroid nodules as small as 4-5 mm were identified. Follicular adenomas appeared as well-circumscribed nodules of heterogeneous intensity, increasing significantly in signal with long TRs/TEs. Colloid cysts and hemorrhagic cysts had homogeneous high signal with both short and long TRs/TEs. Two of three carcinomas were seen as poorly marginated lesions with associated cervical lymphadenopathy clearly depicted as increased intensity with long TRs/TEs. A follicular adenoma containing microscopic papillary carcinoma appeared similar to other benign adenomatoid nodules. A functioning nodule was isointense with normal gland at all pulse sequences. Characteristic patterns of diffuse abnormality were observed in cases of multinodular goiter, Hashimoto thyroiditis, and Graves disease, although additional cases are required to determine specificity. High-field-strength surface-coil MR imaging appears to be a sensitive method for identifying gross morphology of focal, multinodular, and diffuse disorders of the thyroid and involvement of surrounding structures in the neck.

Adult↗
PubMed1987

Digital chest imaging: comparison of two film image digitizers with a classification task.

A classification test was used to compare the results of digitizing chest radiographs with a linear diode array camera and a laser scanner. The ability of B readers to classify a pneumoconiosis test set from original radiographs and the digitized images was compared. The classification of profusion was impaired when images were digitized with the diode array camera but not when they were digitized with the laser scanner. The impairment found with images digitized with the linear diode array camera was overcome with use of a zoom function at the display station. The size of areas of opacification was overestimated on images from both scanners. Variation between and within observers (kappa approximately equal to 0.6) was consistent over observers and over modalities.

Evaluation Studies as Topic↗
PubMed1987

High-field MR imaging of extracranial hematomas.

The MR features of 20 extracranial hematomas studied on a 1.5-T system and imaged with both short repetition-time/echo-time (TR/TE) and long TR/TE pulse sequences were reviewed. In four of five acute hematomas (those less than 7 days of age), signal intensity was markedly decreased on long TR/TE images and was either intermediate or slightly decreased on short TR/TR images. Fourteen subacute hematomas (7 days to 7 weeks of age) and one chronic hematoma (9 months) were studied. The appearance of the subacute lesions varied from intermediate to high intensity on short TR/TE sequences, but all demonstrated increased signal on long TR/TE sequences. A low-signal rim was noted at the margin of nine subacute lesions. In one patient with this finding, pathologic examination showed that the low-signal margin corresponded to a region containing hemosiderin-laden macrophages at the periphery of the hematoma. These results correlate well with those reported for intracranial hematomas examined at this field strength. We conclude that analysis of signal-intensity patterns at 1.5 T is useful in staging the evolution of hematomas.

Adult↗