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Biomedical subjects

D Ling

Publications and source records attributed to D Ling.

At least 37 records · Page 2Linked to original sources
PubMed1986

MRI of extracranial hematomas: preliminary observations.

Thirteen patients (16 examinations) with extracranial hematomas (four mediastinum, three pelvis, two calf, two psoas muscle, one liver, one abdominal wall) were examined with magnetic resonance imaging (MRI). With the exception of an acute hematoma (less than 48 hr), which did not have a distinctive MRI appearance, subacute and chronic hematomas (up to 10 months' duration) had areas of high signal intensity on both T1- (TR 500/TE 30) and T2- (TR 1500/TE 90) weighted pulse sequences. The hematomas in 10 of the patients were also evaluated by computed tomography (CT). The MRI findings complemented those seen on CT. Low-intensity parts of the hematoma on both T1- and T2-weighted images corresponded to areas of high attenuation on CT, whereas high-intensity zones correlated with regions of low attenuation. This observation was more apparent on the T1-weighted images. While older hematomas did not exhibit areas of hyperdensity that would allow a specific diagnosis on CT, MRI did demonstrate regions of high signal intensity indicative of hemorrhage.

Abdominal Muscles↗
PubMed1986

Isolation and structure determination of crisamicin A, a new antibiotic from Micromonospora purpureochromogenes subsp. halotolerans.

A new antibiotic, crisamicin A, with in vitro activity against Gram-positive bacteria, B16 murine melanoma cells, and herpes simplex, vaccinia, and vesicular stomatitis viruses, has been isolated from Micromonospora purpureochromogenes subsp. halotolerans. On the basis of 1H and 13C NMR spectroscopic, high resolution field desorption mass spectrometric, and circular dichroism studies of the antibiotic and several of its derivatives, the structure of crisamicin A has been assigned.

Anti-Bacterial Agents↗
PubMed1985

Hepatic metastases studied with MR and CT.

Examinations of the liver using magnetic resonance (MR) and computed tomography (CT) were performed on 50 patients with hepatic metastases. MR and CT were comparable in their ability to detect metastases, which generally appeared hypointense compared with normal liver parenchyma on T1-weighted MR images and hyperintense on T2-weighted images. The MR imaging techniques that were most reliable in detecting metastases were inversion recovery and a relatively T2-weighted, spin-echo technique (TR = 1,500 msec, TE = 60 msec). We conclude that CT, because of its shorter imaging time, greater spatial resolution, and lower cost, should remain the preferred screening test for hepatic metastases. MR imaging should be reserved for patients with equivocal CT findings and for patients in whom there is persistent clinical suspicion of hepatic metastases despite a negative CT examination.

Adult↗
PubMed1985

Radiation fibrosis: differentiation from recurrent tumor by MR imaging.

Magnetic resonance (MR) images of 21 patients who had undergone radiation therapy were analyzed and compared with those of 15 patients who had untreated tumors. T2-weighted images (TR = 1,500 msec, TE = 90 msec) were most helpful in distinguishing recurrent tumor from radiation fibrosis. Radiation fibrosis, like muscle, usually remained low in signal intensity on T2-weighted images, while tumor demonstrated higher signal intensity. In no patient was the signal intensity of tumor the same or less than muscle on the T2-weighted images. However, relatively high signal intensity on T2-weighted images is not specific for tumor recurrence and may be seen in acute radiation pneumonitis, infection, hemorrhage, and even pulmonary radiation fibrosis.

Adult↗
PubMed1984

Use of computed tomography in pediatric oncology.

Computed tomography (CT) has dramatically changed the imaging of pediatric oncologic disease. CT precisely displays and characterizes cross-sectional anatomic pathology. This provides important information for diagnosing and staging tumors in infants and children. The principles, techniques, and indications for computed tomography in the evaluation of pediatric extracranial tumors are reviewed in this article. Selected applications of computed tomography for pediatric tumors of the mediastinum, chest wall, lung parenchyma, abdomen, pelvis, and extremities are discussed and illustrated.

Abdominal Neoplasms↗
PubMed1984

Fatty infiltration of the liver: demonstration by proton spectroscopic imaging. Preliminary observations.

Two normal volunteers and three patients with CT evidence of fatty infiltration of the liver (two nonuniform, one diffuse) were studied to determine whether magnetic resonance imaging using a pulse sequence designed to differentiate fat and water could be used to detect fatty infiltration of the liver in human beings. The magnetic resonance technique used a modified spin echo technique (simple proton spectroscopic imaging) that was designed specifically to exploit the difference in the rate of precession between the protons in a water molecule and the protons in a fatty acid molecule. Images were obtained using in-phase and opposed techniques and were added or subtracted in order to obtain pure water and pure fat images. Quantitative data showed that fatty liver can be separated from normal liver using the spin echo technique, and that the opposed image of the proton spectroscopic technique is more sensitive to small changes in hepatic fatty content than in-phase images with any echo time.

Electron Spin Resonance Spectroscopy↗
PubMed1984

Magnetic resonance imaging of abdominal and pelvic lymphadenopathy.

The authors report their experience with magnetic resonance imaging (MR) in 20 patients with CT-proved lymphadenopathy of the abdomen and pelvis. Signal intensity from abnormal nodes was intermediate between fat and muscle (T1 longer than fat and muscle; T2 equal to or slightly shorter than fat but longer than muscle) and was shown best in the spin-echo mode with a TR of 900 msec. and a TE of 30 msec. Abnormal nodes were identified by their increased size and other morphological changes rather than by tissue characteristics established by signal intensity information. Lymphadenopathy due to lymphoma could not be differentiated from that due to metastases. MR detected all lymphadenopathy originally documented by CT and in addition easily distinguished blood vessels from lymph nodes; on the other hand, CT offered better spatial resolution and could be completed in less time.

Abdomen↗
PubMed1984

Magnetic resonance imaging of abdominal aortic aneurysms.

Magnetic resonance imaging (MRI) was performed in 20 patients with radiologically or surgically proven abdominal aortic aneurysms using a Siemens Magnetom scanner with a 0.35-T superconductive magnet. On MRI, rapidly flowing blood emits little or no signal and appears black; stagnant blood, turbulent flow, and atheromatous plaques produce signals of various intensities and are imaged as light to medium gray. Of nine patients who underwent surgical repair, MRI correctly demonstrated the origin of the aortic aneurysm in nine and accurately determined the status of the iliac arteries in eight. In two patients in whom intravenous contrast administration was contraindicated, MRI provided the correct diagnosis of a mycotic pseudoaneurysm in one and clearly distinguished the iliac arteries from the surrounding fibrosis in the other. Of 11 patients who did not have surgical repair, MRI findings correlated well with other radiologic studies. MRI was found to be more reliable than sonography in determining the relation between the aneurysm and the renal arteries as well as the status of the iliac arteries. Despite these advantages, the authors still advocate sonography as the screening procedure of choice in patients with suspected abdominal aortic aneurysms because of its lower cost and east of performance. MRI should be reserved for patients who have had unsuccessful or equivocal sonographic examinations.

Aged↗
PubMed1983

Primary lower extremity lymphedema: CT diagnosis.

The CT findings of two cases of primary lymphedema of the lower extremities are presented. CT showed a coarse, nonenhancing, reticular pattern in an enlarged subcutaneous compartment. CT excluded the diagnosis of secondary lymphedema from an obstructing mass by demonstrating a normal retroperitoneum and pelvis. The CT findings are correlated with pedal lymphangiograms.

Adult↗
PubMed1982

Cued Speech and the reception of spoken language.

This study was designed to investigate the effect of Cued Speech on the speech reception abilities of profoundly hearing-impaired children under seven conditions of presentation: audition; lipreading; audition and lipreading; cues; audition and cues; lipreading and cues; and audition, lipreading, and cues. The 18 subjects had been taught through the use of Cued Speech for at least 4 years. The subjects were presented with specially designed speech tests (syllables and key words in sentences) which had been recorded on color videotape, and they responded in writing. Speech reception scores of over 95% with the key word in sentence materials and over 80% with the syllables were obtained with lipreading plus cues, and with audition, lipreading plus cues. Equally high levels of accuracy in speech reception by such children have not previously been reported. The subjects also demonstrated the ability to use audition with the sentence materials, both in combination with lipreading and with cues, though there were large individual differences under these conditions. Speech reception abilities in the lipreading-plus-audition condition were highly correlated with scores for speech production, whereas language attainments were correlated with reception through Cued Speech. The implications of these findings to the field of aural rehabilitation are discussed.

Adolescent↗
PubMed1981

Effects of ischemia on left ventricular regional function in the conscious dog.

Three-dimensional regional geometry of the left ventricle was assessed in seven conscious trained dogs chronically implanted with pulse-transit ultrasonic-dimension transducers. Minor and major axis segment lengths and wall thickness were measured in the distribution of the left anterior descending coronary artery; transmural pressure (TMP) was measured with high-fidelity micromanometers. Data were recorded during the control state and following 30 s and 30 min of ischemia. Dimensions were normalized as a fractional extension from the length at zero TMP (Lo). Dynamic cube mass was calculated and remained constant throughout the cardiac cycle in both control and ischemic states, although the calculated mass decreased by an average of 5% during ischemia. The slope constants of the exponential diastolic pressure-dimension relationship increased following acute coronary occlusion indicating increases in regional myocardial stiffness with increasing periods of ischemia. Coronary occlusion also was associated with an increase in the Lo measurements in the major and minor axis dimensions and a decrease in the wall thickness Lo. These findings are consistent with an ischemia-induced plastic deformation of the regional myocardium defined as creep. Thus, acute ischemia results in a decline of regional systolic function, induces myocardial creep, and causes an immediate and sustained increase in regional myocardial stiffness.

Animals↗
PubMed1979

Regional diastolic mechanics of the left ventricle in the conscious dog.

In eight chronically instrumented conscious dogs, apical and middle left ventricular transverse diameters were measured with pulse-transit ultrasonic dimension transducers. Intracavitary apical and midventricular pressures and intrapleural pressure were measured with micromanometers. Both diameters were normalized as a percent extension from the dimension at zero transmural pressure, determined during a transient vena caval occlusion. During the rapid phase of diastolic filling, there was a 2--5 mmHg pressure gradient from the midventricle to the apex. During late rapid filling, the apical transmural pressure and diameter increased more rapidly and reached diastasis 17 +/- 4 ms earlier than the corresponding midventricular measurements (P less than 0.01). The static diastolic pressure-dimension characteristics at the apical and midventricular levels were not significantly different (P greater than 0.30). The dynamic diastolic pressure-dimension relationship was also similar at the two levels and could be represented by a model incorporating parallel viscous properties. Because of regional differences in pressures and dimensions, however, the dynamic relationship could not be modeled when pressure was compared to the dimension at a different level. Thus, diastolic pressures should be measured at the same level as dimensions when assessing left ventricular diastolic mechanics.

Animals↗
PubMed1979

The Nakasuk Project- the conservative treatment of chronic otitis media in Inuit elementary school children.

Modalities of local medical treatment of chronic otitis media in Inuit elementary school children were evaluated over a period of three and a half years in a project associated with the provision of amplification (hearing aids) for students who had significant conductive hearing deficits which interfered with their ability to communicate. The significant medical and educational benefits derived are reviewed.

Acetates↗
PubMed1978

Genetic aspects of the BOR syndrome--branchial fistulas, ear pits, hearing loss, and renal anomalies.

A pedigree of branchio-oto-renal dysplasia (the BOR syndrome) is reported, including the documentation by serial audiometric studies of the onset and rapid progression of hearing loss in the twin sister of an affected child. The literature on this syndrome is analyzed to derive some figures for use in genetic counseling of such families. Branchio-oto-renal dysplasia is an autosomal dominant disorder in which affected individuals may have preauricular pits, lachrymal duct stenosis, hearing loss, branchial fistulas or cysts, structural defects of the outer, middle, and inner ear, and renal anomalies, which may range from mild hypoplasia to complete absence. Not all features of the syndrome are expressed in all carriers of the gene, but few carriers lack all the features, and the pits, branchial clefts, and hearing loss, are frequently expressed. Those offspring of affected persons who have pits or fistulas are likely (about 80%) to have hearing loss of varying degrees of severity. A minority of heterozygotes (about 7%) may have hearing loss without pits or fistulas. The risk of severe renal malformation is probably fairly low. Whether families that show dominant inheritance of pits, clefts, and deafness without renal anomalies represent variants of the BOR syndrome or a separate entity (the BO syndrome), is still not clear. At present, any individual with preauricular pits and branchial clefts deserves both otologic and renal investigation.

Abnormalities, Multiple↗
PubMed1978

Speech development in hearing-impaired children.

Many hearing-impaired children are unable to speak intelligibly. Research indicates, however, that patterns of errors typically found in the speech of such children could be largely avoided by systematic teaching. The purpose of this paper is to present and discuss a model for the progressive development of speech skills to the levels of automaticity required for fluent spoken language.

Child↗