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Biomedical subjects

A W Zwamborn

Publications and source records attributed to A W Zwamborn.

At least 19 recordsLinked to original sources
PubMed2000

US and fluoroscopic-guided percutaneous jejunostomy: experience in 49 patients.

PURPOSE: To assess the feasibility and safety of a variety of techniques for percutaneous jejunostomy. MATERIALS AND METHODS: Percutaneous jejunostomy was attempted on 53 occasions in 49 patients under US and fluoroscopic guidance. During the study period, thicker needles, Cope anchors, and intravenous glucagon were introduced to improve access, dilate, and immobilize the jejunum. Technical success rates, complications, catheterization period, and reasons for catheter removal were prospectively studied. Prognostic factors for successful procedures and complications were determined. RESULTS: Forty-six (87%) procedures were technically successful. Previous gastrointestinal surgery (P = .01) and a combination of thicker needles, Cope anchors, and intravenous glucagon (P = .0001) were associated with a higher technical success rate. Complications (n = 6; pericatheter leakage in four of six) were observed more frequently in older patients (P = .01). The 30-day mortality rate was 17%, one death may have been procedure related. Forty-three catheters were removed (elective, n = 36; other, n = 7) after 1-597 days (median, 49). Three catheters remained in situ for 139-482 days (median, 410). CONCLUSIONS: Percutaneous jejunostomy is a feasible and relatively safe technique for long-term feeding. Leakage is the main problem, which warrants additional study.

Adult↗
PubMed1999

Endoanal MR imaging of the anal sphincter in fecal incontinence.

Fecal incontinence is a major medical and social problem. The most frequent cause is a pathologic condition of the anal sphincter. Endoanal magnetic resonance (MR) imaging allows detailed visualization of the normal anatomy and pathologic conditions of the anal sphincter. The hyperintense internal sphincter appears as a continuation of the smooth muscle of the rectum; the hypointense external sphincter surrounds the lower part of the internal sphincter. A sphincteric defect is seen as a discontinuity of the muscle ring. Scarring appears as a hypointense deformation of the normal pattern of the muscle layer. Two external sphincteric patterns may be misdiagnosed as defects: a posterior discontinuity (often seen in young male patients) and an anterior discontinuity (often seen in female patients). Atrophy of the external sphincter is easily detected on coronal MR images by comparing the thicknesses of all anal muscles. Endoanal MR imaging is superior to endoanal ultrasonography because of the multiplanar capability and higher inherent contrast resolution of the former. Use of endoanal MR imaging may lead to better selection of candidates for surgery and therefore better surgical results. Endoanal MR imaging is the most accurate technique for detection and characterization of sphincteric lesions and planning of optimal therapy.

Anal Canal↗
PubMed1998

Vertebral dimensions: influence of X-ray technique and patient size on measurements.

In this study a new reference value, "corrected vertebral dimension," is presented for vertebral height measurements. Of 68 females (age 18-88 years; mean 44.2 years) and 40 males (age 16-81 years; mean 55 years) the projected vertebral dimensions (T4-L5) were measured on lateral radiographs. In addition to this, the vertebra-to-film distances (VFD) were measured and a fixed focus-to-film distance (FFD) was used during the study. Corrected dimensions of the thoracic and lumbar vertebrae (T4-L5) were calculated using the FFD and VFD. These corrected dimensions were then used to recalculate projected vertebral dimensions at different focus-to-film distances. The applied geometric corrections were verified in a phantom study representing an in vitro situation. The results indicate that studies using different X-ray techniques for making lateral radiographs of the spine can become comparable when using corrected vertebral dimensions.

Adolescent↗
PubMed1998

Female pelvic floor: endovaginal MR imaging of normal anatomy.

PURPOSE: To demonstrate the anatomy of the female pelvic floor with endovaginal magnetic resonance (MR) imaging. MATERIALS AND METHODS: Ten healthy nulliparous volunteers (age, 22-26 years) underwent MR imaging with an endovaginal coil. Findings on endovaginal MR images in the volunteers were correlated with findings on endovaginal MR images and cross-sectional anatomic slices obtained in three cadavers. RESULTS: The endovaginal coil was well tolerated by all volunteers. Pelvic floor structures such as the pelvic diaphragm and the urogenital diaphragm were well depicted. Previously undescribed urethral supporting structures--the periurethral and paraurethral ligaments--were visualized. The zonal anatomy of the urethra was clearly visible. The endovaginal MR imaging findings in the volunteers correlated with the endovaginal MR findings and gross anatomy in the cadavers. CONCLUSION: Endovaginal MR imaging clearly demonstrates the anatomy of the female pelvic floor and urethra.

Adult↗
PubMed1997

Correlating sheet plastinated slices, computed tomography images and magnetic resonance images of the pelvic girdle: a teaching tool.

Sheet plastination is currently used to produce anatomical slices of different body structures, allowing one to study and teach their topography in an anatomically correct state. Correlation with computed tomography (CT) and magnetic resonance imaging (MRI) techniques gives more insight into their anatomy. Using two female cadaver pelvises CT and MRI were performed. One pelvis was used to prepare 2-mm-thick coronal plastinated slices according to the technique described by von Hagens. We found a good overall correlation between plastinated slices, CT and MRI images. This combined approach provides a unique anatomical insight and is a valuable addition to other teaching tools used by medical students, radiologists and anatomists.

Anatomy, Cross-Sectional↗
PubMed1996

Endoanal MRI of the anal sphincter complex: correlation with cross-sectional anatomy and histology.

The purpose of this study was to correlate the in vivo endoanal MRI findings of the anal sphincter with the cross-sectional anatomy and histology. Fourteen patients with rectal tumours were examined with a rigid endoanal MR coil before undergoing abdominoperineal resection. In addition, 12 cadavers were used to obtain cross-sectional anatomical sections. The images were correlated with the histology and anatomy of the resected rectal specimens as well as with the cross-sectional anatomical sections of the 12 cadavers. The findings in 8 patients, 11 rectal preparations, and 10 cadavers, could be compared. In these cases, there was an excellent correlation between endoanal MRI and the cross-sectional cadaver anatomy and histology. With endoanal MRI, all muscle layers of the anal canal wall, comprising the internal anal sphincter, longitudinal muscle, the external anal sphincter and the puborectalis muscle were clearly visible. The levator ani muscle and ligamentous attachments were also well demonstrated. The perianal anatomical spaces, containing multiple septae, were clearly visible. In conclusion, endoanal MRI is excellent for visualising the anal sphincter complex and the findings show a good correlation with the cross-sectional anatomy and histology.

Adult↗
PubMed1994

Skin thickness does not reflect bone mineral density in postmenopausal women.

Skin and bone both contain primarily type I collagen in connective tissue matrices and are assumed to be related due to this common organic constituent. The purpose of this study was to investigate whether skin thickness measurements by ultrasound (US) could be used for screening for low bone mass. In 94 healthy, white, non-smoking women, 1-3 years postmenopause, the thickness of the skin of the left upper arm and forearm was measured by ultrasound (US). These measurements were compared with values of bone mineral density (BMD) as measured by quantitative computed tomography (QCT) of the lumbar spine and quantitative video micro-densitometry (QMD) of the hand. The correlation found between US skin thickness measurements and BMD results was of low magnitude and not significant. It is concluded that US measurements of skin thickness cannot be used to screen early postmenopausal women for low bone mass.

Bone Density↗
PubMed1993

Cross-sectional and longitudinal study of age-related phalangeal bone loss in adult females.

To establish a comprehensive model for peripheral phalangeal bone loss, bone mass was studied in 1984 and 1989 using quantitative microdensitometry (QMD) in a total of 330 healthy women (age range 43-78.7 years). Bone mass and changes in bone mass were analyzed in relation to age and menopausal status. Ideal and nonideal populations were distinguished to assess the effect of diseases and medication. Both groups showed a decrease in bone mass, which proved to be more dependent on menopausal status than on age. A substantial loss started in the ideal group in the early postmenopausal period and in the nonideal group in the premenopausal period. Because the nonideal group started to lose bone at an earlier stage, the lifetime risk for osteoporosis is higher than in the ideal group.

Adult↗
PubMed1991

Determinants of bone mineral content in childhood.

In a sample of 1190 children (574 boys and 616 girls), aged 6.8-10.7 years, bone mineral content was studied using quantitative röntgen microdensitometry (QMD) at the diaphyseal and the metaphyseal site of the left second digit. Percentile curves of bone mineral density was determined by skeletal age for boys and girls separately. Bone mineral content at the diaphyseal site was significantly associated with skeletal age, height and body weight in boys and girls and with chronological age at the metaphyseal site in boys. In girls higher levels of bone mineral content were observed in those with a skeletal age greater than 7.3 years, compared to those with a skeletal age equal to or less than 7.3 years, adjusted for height and body weight. In boys a higher level of bone mineral content was found in those with a height greater than 138 cm, adjusted for skeletal age, compared to those with a height equal or less than 130 cm, at the diaphyseal and metaphyseal site. Girls with a relatively higher body weight had lower levels of bone mineral content at the metaphyseal site.

Age Determination by Skeleton↗
PubMed1988

A cross-sectional study of age-related loss of mineral content of phalangeal bone in men and women.

The bone mineral content of the second phalanx of the second digit was studied by quantitative microdensitometry. It is concluded that age-dependent loss of bone is a generalised phenomenon in men and women that occurs at different rates at different ages. In women, an accelerated rate of bone loss is observed between 50 and 57 years of age; in men such an acceleration is observed after 68 years of age. It appears that in a selected "ideal" population (with no disease or medication that may influence bone metabolism) the rate of bone mineral loss in women of 50-57 years of age is greater than in an unselected normal population. Furthermore, especially in the 50-57 years age group, the rate of loss at the mid-shaft of the phalanx in women is higher than at a site 25% from the proximal end. In men the rate of bone mineral loss at the 25% site exceeds that at midshaft, especially in the 68-75 year age group.

Absorptiometry, Photon↗
PubMed1987

Microdensitometric analysis of bone structures in X-ray images.

The careful evaluation of bony structure is important in the study of normal bone and bone disorders. This study describes bony structure as seen in the X-ray pattern of the phalanges of the hand using quantitative microdensitometry. Normalised scans of bony density show the regular and irregular distribution of the trabeculae. Two properties were determined from these densitometric findings: the mean transverse coarseness (C) indicating fluctuations of horizontal density and the overall standard deviation indicating axial homogeneity (H). This investigation demonstrates the applicability of the method: it shows a significant correlation with radiological diagnosis and that microdensitometry is a reliable method for quantifying the coarseness and homogeneity of bone structure.

Bone and Bones↗
PubMed1987

A study on the phalanx bone mineral content in 273 normal pre- and post-menopausal females (transverse study of age-dependent bone loss).

Quantitative Röntgen microdensitometry (QMD) can be used to provide a precise quantification of mean specific bone mass (rho) from standardized radiographs. The method is simple, non-invasive, low in cost and suitable for frequent repetition. Bone mineral mass at the mid-length (largely cortical bone) of the middle phalanx of digital II of the left and right hands was investigated. Normalized quantification of bone structure can be achieved with a precision (coefficient of variation) of the order of 1%. Rho values were determined for the right and left phalanx in 273 apparently healthy women 43-73 years of age (mean menopausal age, 49.8 years) in an attempt to differentiate between normal changes with age and excessive bone mineral loss. The mean rate of age-dependent bone mineral loss was -1.4% per year in pre-menopausal women; in post-menopausal women between 50 and 57 years it was -3.5% per year and between 58 and 73 years it was -0.8% per year. The mean rate of change of bone mineral mass in the same group, as a function of the number of years after menopause, was -1.9% per year for the group 2-8 years after menopause and +0.1% per year for the group 9-20 years after menopause.

Adult↗
PubMed1985

Roentgendensitometric study of the phalanx.

This is an outline of a radiologic assessment of bone mineral measurements for diagnosis that is simple and low in cost. Bone mineral content equivalent values (BMCE) were determined of phalanges. Since phalanges have different dimensions the BMCE values per square millimeter surface area, bone mean mineral equivalent values (BMME) were determined. In normal subjects it was shown that over a period of 9 months a coefficient of variation for BMCE and BMME was found of 8 and 9%, respectively, indicating a change during the investigation period (precision of the technique has a CV for BMCE of 4% and for BMME of 3%). The clinical application of microdensitometry and of the single photon absorption method was tested and compared. Both methods resulted in similar findings, microdensitometry however also provides a qualitative assessment of bone characteristics.

Absorptiometry, Photon↗
PubMed1984

A study of the radiographic aluminum equivalent values of the mandible.

A longitudinal study of bone changes in the mandible was conducted. Duplicate radiographs were taken at 3-month intervals with the use of a positioning instrument, which included an aluminum calibrating wedge. The in-duplicate values obtained over the investigation period made it possible to assess the precision of the method and to analyze effects that take place with time. Significant bone changes were observed in seven volunteers between various observation periods at intervals of 6 and 9 months.

Absorptiometry, Photon↗
PubMed1980

Videodensitometry for measuring blood vessel diameter.

A method employing a special computer for determining the internal diameters of blood vessels from photofluorographic image is described; in vitro and in vivo experiments are performed with the system. The amount of contrast medium injected is restricted to 4 times 3 ml, and it is possible to determine the diameter (in the range from 2 to 16 mm) at any place where blood vessels can be catheterized. In the in vivo experiments the maximum systematic error is +/-5 percent in the 7 to 8 mm range.

Absorptiometry, Photon↗