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Biomedical subjects

J J Phillips

Publications and source records attributed to J J Phillips.

10 recordsLinked to original sources
PubMed1992

Influence of the mode of preparation on the long-term efficacy of homologous costal cartilage implants.

Devitalized homologous costal cartilage is widely employed as an implant in the management of the saddle nose. The tissue response induced by the implant is a combination of enveloping fibrosis and implant resorption, which will probably, ultimately, be complete. We have studied the balance between resorption and fibrosis, following different modes of cartilage preparation, in the mouse. Homologous costal cartilage was devitalized by four common methods--irradiation, formalin, glutaraldehyde and alcohol. Segments of this cartilage were inserted at separate sites in the subcutaneous plain of the tail. These implants were harvested after one year for histology. Variations in the mode of cartilage devitalization, while inducing variations in the degree of the tissue response, did not influence the balance between fibrosis and resorption. Thus the long term maintenance of tissue bulk following homologous cartilage implantation is not influenced by the mode of preparation. Evidence suggests that the ultimate cosmetic results of autologous and homologous costal cartilage implantation would be much the same, and the use of homologous cartilage must be justified on other grounds.

Animals↗
PubMed1991

MR and CT imaging of ethanol-treated liver tumors in an animal model.

To characterize the radiographic appearance of liver lesions over time following ethanol injection, seven New Zealand white rabbits underwent surgical implantation of small fragments of VX-2 carcinoma within the liver. Upon reaching 1 cm in diameter, a tumor nodule was directly injected with absolute ethanol. Another nodule in the same animal was injected with saline as a control. Imaging was performed 6-24 days after the injections by high resolution CT and MRI, and correlation obtained with the pathologic specimens. Long TR spin-echo MR sequences were found to characterize the ethanol-treated regions of liver most accurately. Liver tissue infarcted by alcohol could be differentiated from tumor and necrosis by virtue of its short T2 relaxation value. There were no distinguishing features by other imaging techniques between the ethanol-treated and control tumor nodules. Peripheral contrast enhancement was demonstrated in both, corresponding to fibrous tissue around the ethanol-injected regions, and to viable tumor in the case of controls.

Animals↗
PubMed1991

Adrenal gland volume determination by computed tomography and magnetic resonance imaging in normal subjects.

To compare the usefulness of computed tomography (CT) and magnetic resonance imaging (MRI) for the quantitative determination of adrenal gland size in human subjects, adrenal gland volumes were determined by both techniques in five female and five male, normal, nonstressed adult volunteers. Mean left and right adrenal volumes were slightly larger by CT, and the left adrenal volume was slightly larger than the right by both imaging techniques. Volume determinations by CT and MRI correlated +0.85 and +0.82 for the left and right glands, respectively. Body surface area was highly correlated, and sex moderately correlated, with left and right adrenal volumes by both techniques. Both CT and MRI somewhat overestimated the known volumes of a set of phantoms, CT by an average of 42% and MRI by an average of 20%. The results of this initial study suggest that MRI holds promise as a technique for in vivo adrenal gland measurements, and that the influence of both body surface area and sex should be considered in comparative studies of adrenal size.

Adrenal Glands↗
PubMed1991

Magnetic resonance imaging of pediatric head and neck cystic hygromas.

We retrospectively reviewed the magnetic resonance imaging (MRI) findings of eight pathologically proved cystic hygromas in seven pediatric patients. All lesions showed multiple cysts, best depicted on T2-weighted images (T2WI). Six of the eight lesions had well-defined borders. Fluid-fluid levels were visualized in seven of eight lesions, with very high signal intensity of the upper fluid on T2WI. On T1-weighted images, all lesions showed a mean signal intensity greater than that of muscle (1.6 times) and cerebrospinal fluid (CSF; 4.04 times) and less than that of fat (0.5 times). On T2WI, the mean signal intensity was greater than that of CSF (1.8 times), muscle (9.45 times), and fat (2.54 times). Chemical analysis of the cystic fluid from one lesion showed high lipid content and hemorrhage, consistent with the preoperative and in vitro MRI findings on the fluid from the same patient. Lesion anatomic distribution showed frequent posterior triangle involvement; however, the epicenter of 75% of the lesions was outside the posterior triangle. Only one lesion had involvement limited to the posterior triangle. There was equal distribution of right and left sides and no midline lesion. Seven lesions displaced the sternocleidomastoid muscle laterally, whereas one displaced it posteriorly, with no evidence of muscle infiltration. Only those patients with submucosal involvement (two of seven) had respiratory symptoms. Gadolinium provided no additional information with regard to diagnosis or extent of involvement. Our experience indicates that MRI is useful in the diagnosis and treatment planning of cystic hygromas.

Child, Preschool↗
PubMed1990

Acute infective airway obstruction associated with subglottic stenosis.

Pre-existing subglottic stenosis in a 22-month-old child with laryngotracheobronchitis resulted in failure to intubate the trachea on the intensive therapy unit. Tracheostomy was necessary in the operating theatre to secure the airway. The implications for safe management are discussed.

Acute Disease↗
PubMed1988

Visual contrast enhancement with a patterned overlay.

A dot-screen pattern was devised and superimposed on computed tomography images to improve contrast at a viewbox. The phenomenon is believed to be probably related to lateral inhibition. To evaluate its usefulness, the device was used on 12 images (eight showed metastatic liver lesions, and four were normal); each image was viewed without the device by ten observers. Three control images were viewed a second time without the device. The remaining nine images were viewed a second time with the device. The overlay improved diagnostic performance in nine observers. Sensitivity improved by 12%, and confidence in true-positive findings increased by 41.6%. Forty-five percent of false-negative findings were converted to true positive with the use of the overlay.

Humans↗
PubMedDate not supplied

Motion artifact suppression technique (MAST) for MR imaging.

A technique has been developed that significantly improves the image resolution and reduces motion artifacts in conventional two-dimensional Fourier transform and three-dimensional Fourier transform magnetic resonance imaging sequences. Modifications on the gradient waveforms completely refocus the transverse magnetization at the echo time, regardless of the motion occurring between the time of the 90 degrees radiofrequency excitation and the echo time (within-view). This accomplishes suppression of motion artifacts and regains the signal from flowing blood and CSF. Images of the head, abdomen, chest, and spine are reproduced which show the increase in signal and anatomical detail that would otherwise be degraded and lost in artifact noise. This technique has reduced the practical difficulty of obtaining clinically diagnostic T2-weighted abdominal images. It also has allowed diagnostic quality T1- and T2-weighted images to be obtained with one acquisition per view, thus reducing the total scan time.

Brain Stem↗
PubMedDate not supplied

Perirenal hemangioendothelioma in a newborn: sonograph and MR findings.

This is a case report of perirenal hemangioendothelioma in a newborn and discussion of lesions in the perirenal space in newborns. The findings in this case, high echogenicity on sonographic images and high signal intensity on T2-weighted spin echo magnetic resonance images, mimic those described for hemangiomas in other locations.

Hemangioendothelioma↗
PubMedDate not supplied

MRI of the upper abdomen using motion artifact suppression technique (MAST).

Magnetic resonance imaging of the upper abdomen has been hampered by motion artifacts that cause suboptimal image quality. A promising software solution to this problem, motion artifact suppression technique (MAST), is described. Using mathematically determined refocussing gradients, it has improved image clarity significantly. Unlike alternate techniques such as respiratory gating, there is no increase in scan time, and patient throughput is expedited.

Abdomen↗