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Biomedical subjects

M I Boechat

Publications and source records attributed to M I Boechat.

At least 37 records · Page 2Linked to original sources
PubMed1992

Congenital bladder rupture and urine ascites secondary to a sacrococcygeal teratoma.

A case of congenital bladder rupture with urine ascites and bilateral hydronephrosis secondary to a sacrococcygeal teratoma obstructing the bladder outlet is presented. As no evidence of pulmonary hypoplasia and renal dysplasia was present, with rapid recovery of renal function after decompressive surgery, the infravesical obstruction probably occurred late in the fetal period. The bladder rupture resulting in internal decompression may have constituted an additional protective mechanism for the preservation of renal function.

Ascites↗
PubMed1992

Performance characteristics and image fidelity of gray-scale monitors.

Gray-scale monitors are an essential element of electronic radiology, and their ability to provide images that are perceived to be identical to those available on conventional or laser-printed film is crucial to success of electronic radiology. Image fidelity is measured in physical characteristics (luminance, dynamic range, distortion, resolution, and noise) and with psychophysical techniques, including receiver operator characteristics analysis with clinical images and testing with contrast-detail patterns to determine threshold contrast. Currently, laser-printed images facilitate greater information transfer than does a gray-scale monitor because of their higher absolute luminance (500 ft-L vs 60 ft-L), greater perceived dynamic range, and better spatial resolution. In the near future, the developments of gray-scale monitors with 150-200 ft-L luminance, a display standard based on just noticeable differences, and algorithms to improve similarities between gray-scale display images and laser-printed images will help increase the acceptability of monitors as a means to make primary diagnoses.

Computer Peripherals↗
PubMed1992

Subperiosteal resorption: effect of full-frame image compression of hand radiographs on diagnostic accuracy.

Image compression is essential to handle a large volume of digital images, including computed tomographic, magnetic resonance, computed radiographic, and digitized images in a digital radiology operation. Developed during the past few years, full-frame bit allocation performed with the cosine transform technique has been proved to be an excellent irreversible image compression method. This article describes the effect, on the accuracy of diagnosis of subperiosteal resorption, of using the hardware compression module to produce hand radiographs. Receiver operating characteristic analysis of the interpretation of 71 radiographs by five observers demonstrated that there is no statistically significant difference in diagnostic accuracy between the original radiographs and compressed and reconstructed images obtained with a compression ratio as high as 20:1.

Bone Resorption↗
PubMed1992

Extended recombinant human growth hormone treatment after renal transplantation in children.

Recombinant human growth hormone (rhGH) was administered to 13 pediatric renal allograft recipients, ages 7.6 to 17.7 yr, who were 14 to 92 months posttransplant and growth retarded as manifested by either a standard deviation (SD) more negative than -2.00 or a height velocity index of less than 25%. The rhGH was given either daily or thrice weekly (0.375 mg/kg/wk) for a period of 12 to 36 months. Growth velocity increased from 2.7 +/- 2.1 SD for the 12-month period before the initiation of treatment of 6.3 +/- 2.9 SD (P less than 0.00005) and 5.2 +/- 2.9 SD (P less than 0.02) after 12 and 24 months of treatment, respectively. Although individual recipients had improvement in their SD scores, the mean values did not increase despite the increased growth velocity. Except for a 0.5-yr increase over 24 months in two recipients, the bone age did not increase at a rate greater than the increase in chronologic age. Four rejection episodes occurred in two recipients during rhGH treatment--an incidence not greater than that which occurred during a comparable time interval before the initiation of treatment. The calculated creatinine clearance declined from 66 +/- 26 SD mL/min/1.73 m2 at the initiation of treatment to 55 +/- 30 SD mL/min/1.73 m2 at 24 months and 52 +/- 28 SD mL/min/1.73 m2 (P = not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Magnetic resonance imaging of the pediatric pelvis.

The increased use of MR imaging in the pediatric population is due to the lack of ionizing radiation, multiplanar imaging capability, and excellent tissue contrast differentiation. MR imaging is most commonly indicated in the evaluation of tumors to provide information about resectability and extent of lesions. It is also useful in the evaluation of congenital anomalies of the pelvic organs. This is a rapidly changing field; the development of fast-scanning techniques and contrast agents for the bowel should further improve the utilization of MR imaging in pediatrics.

Child↗
PubMed1991

Recombinant human growth hormone treatment of children following renal transplantation.

Nine growth-retarded renal allograft recipients received either thrice weekly or daily subcutaneous recombinant human growth hormone (rhGH) for 6-30 months. The annualized growth velocity for the initial year of rhGH treatment was significantly greater than that of the preceding year (2.5 +/- 2.1 vs 5.7 +/- 2.7; P less than 0.0001). There was no advancement in bone age greater than the increase in chronological age, no significant increase in the mean fasting serum glucose or insulin levels, nor significant decrease in the calculated creatinine clearance following rhGH treatment. However, two patients experienced rejection episodes following rhGH treatment indicating the potential adverse consequences of the treatment on allograft function. This will require further delineation in prospective controlled studies. The serum insulin-like growth factor-1 levels significantly increased at 6 months (P less than 0.009) and 12 months (P less than 0.002) following rhGH treatment compared with baseline values. These preliminary data indicate that rhGH treatment may be effective in improving the growth velocity of growth-retarded renal allograft recipients.

Adolescent↗
PubMed1991

Recombinant human growth hormone treatment of children with chronic renal failure: long-term (1- to 3-year) outcome.

Treatment of nine boys, aged 2.8-16.3 years, with growth retardation consequent to chronic renal failure (CRF), with recombinant human growth hormone (rhGH) for 12-36 months demonstrated a significant improvement in growth velocity at each 12-month interval compared with that achieved the year prior to treatment. Despite the acceleration in growth velocity the bone age did not increase more than the increase in chronological age during the period of treatment. The mean calculated creatinine clearance did not decrease significantly during the 36 months of treatment; however, two patients required institution of dialysis at 18 and 30 months following the initiation of rhGH treatment. There was no exacerbation of the glucose intolerance of uremia following rhGH treatment. Currently, six of seven patients who have been treated for more than 24 months have achieved sufficient acceleration of growth velocity to attain a standard deviation score that was more positive than -2.00, and are above the 5th per centile for chronological age on the growth curve. These data indicate that rhGH treatment of growth-retarded children with CRF results in accelerated growth velocity during the 2nd and 3rd years of treatment, and demonstrate the potential for such children to achieve normal stature for chronological age despite the continued presence of renal failure.

Adolescent↗
PubMed1990

False-negative duplex Doppler studies in children with hepatic artery thrombosis after liver transplantation.

Recent reports describe formation of collateral vessels in children who have hepatic artery thrombosis after liver transplantation. This led us to reevaluate the role of duplex Doppler imaging in this population. Among 135 pediatric liver transplant patients, 20 had arteriography for suspected hepatic artery thrombosis. Duplex and/or color Doppler imaging was performed in 13 of these children. The Doppler examination failed to show hepatic artery signals in five patients. Arteriography showed hepatic artery thrombosis in all five. In three of these, subsequent Doppler examinations showed reappearance of arterial Doppler signals. Arteriography confirmed the interval development of collaterals. Hepatic artery signals were found on the Doppler examinations of the remaining eight patients. Four had normal arteriograms, but the remaining four had hepatic artery thrombosis with collateral formation. Patients with hepatic artery thrombosis and collateral circulation tended to have increased diastolic flow (decreased resistive index). In addition, early scans clearly identified patients with complete thrombosis before collateral formation. On the basis of our preliminary experience, a child with a liver transplant and a clinical history strongly suggestive of hepatic artery compromise should have arteriography despite an apparently normal Doppler examination.

Child↗
PubMed1990

Recombinant human growth hormone (rhGH) treatment of children undergoing peritoneal dialysis.

The authors studied the effect of recombinant growth hormone (rhGH) treatment on 5 growth retarded children, age 2 2/12 to 17 8/12 years, who had end-stage renal disease (ESRD) and were undergoing continuous cycling peritoneal dialysis (CCPD). Patients received 0.125 mg/kg of subcutaneous rhGH 3 times weekly. Accelerated height velocity compared to the previous year of CCPD was noted in 2 patients and improvement in the standard deviation score (SDS) as a parameter of improved growth velocity was noted in a third patient. This was associated with an increase in weight and improvement in the midarm muscle circumference (MAMC) suggesting an anabolic effect of rhGH treatment. Bone age advancement was consistent with the period of observation; no advancement greater than that expected for the increase in chronological age was observed. No significant side effects were attributable to rhGH therapy. These preliminary results indicate some growth retarded children without growth hormone deficiency with ESRD undergoing CCPD may respond to exogenous rhGH therapy with an acceleration in growth velocity: However, the failure to achieve uniform acceleration of height velocity indicates the need for controlled studies before rhGH can be recommended for all growth retarded children with ESRD undergoing peritoneal dialysis.

Adolescent↗
PubMed1990

Magnetic resonance imaging of abdominal and pelvic masses in children.

Magnetic resonance imaging is an excellent cross-sectional imaging study for the evaluation of pediatric pathology. This article outlines its role in the evaluation of abdominal masses in children, including lesions arising in the adrenal glands, kidneys, liver, and pelvic organs.

Abdomen↗
PubMed1989

Accelerated growth after recombinant human growth hormone treatment of children with chronic renal failure.

We studied the effect of recombinant human growth hormone treatment on five boys, aged 4.6 +/- 1.8 years, who had chronic renal failure secondary to congenital renal diseases (mean creatinine clearance (+/- SD): 18.3 +/- 6.3 ml/min/1.73 m2 (0.32 +/- 0.11 ml/sec/1.73 m2]. Patients received 0.125 mg/kg of growth hormone three times per week for 1 year. Before beginning treatment, the children had a mean annual growth velocity of 4.9 +/- 1.4 cm/yr (range 3.0 to 6.3 cm/yr), with a mean standard deviation score for a height of -2.98 +/- 0.73 (range -2.16 to -3.59). At the end of therapy, the mean growth velocity had increased to 8.9 +/- 1.2 cm/yr (range 7.5 to 10.7 cm/yr), and the mean height standard deviation score improved to -2.36 +/- 0.83 (range -1.15 to -3.18). Bone age advancement was consistent with the period of growth. Routine laboratory determinations, including results of glucose tolerance testing, did not vary significantly from pretreatment levels. These preliminary data indicate that growth-retarded children with chronic renal failure can respond to exogenous growth hormone therapy with a marked acceleration in growth velocity.

Age Determination by Skeleton↗
PubMed1989

Comparison of 2048-line digital display formats and conventional radiographs: an ROC study.

Observer performance tests were conducted to compare the effects on diagnostic accuracy of digital hard copy and video display formats versus conventional radiographic film. Digital images were obtained by digitizing conventional chest radiographs to a 2048 x 2048 matrix with a laser film scanner. Three digital display formats were used: laser-printed digital film, a 2048-line video monitor without user interaction, and a 2048-line video monitor with user interaction. Thirty-one posteroanterior chest radiographs, determined by consensus of four thoracic radiologists to contain septal lines (n = 11), parenchymal nodules (n = 7), nodules and septal lines (n = 7), or neither abnormality (n = 6), were used for the study. Images were interpreted by four radiologists in four separate viewing sessions. Diagnostic accuracy was determined by receiver-operating characteristic analysis for each observer with each viewing technique. No statistical differences in diagnostic accuracy, determined by the area under the receiver-operating-characteristic curve, were found between the analog film, the digital film, and the two video digital display formats. This preliminary study suggests that 2048-line digital displays may be an acceptable alternative to the traditional lightbox viewing method for the perception of these two abnormalities commonly seen on chest radiographs.

Computer Systems↗
PubMed1989

Cranial arteriovenous malformations in neonates: color Doppler imaging with angiographic correlation.

Five neonates with cranial arteriovenous malformations were studied with color Doppler sonography. Excellent correlation was found between sonography and subsequent angiography. In three patients with vein of Galen aneurysms, sonography showed a cystic structure with rapid or swirling flow. Careful adjustment of the color Doppler system was required to demonstrate flow in another patient with a dural arteriovenous malformation. An arteriovenous fistula in a fifth patient appeared as an area of increased flow. Arterial feeders and major draining veins were visualized in all five patients. Color Doppler imaging also was used to assess the effect of embolic or operative therapy in three of the patients. We conclude that color Doppler sonography is able reliably to characterize flow patterns in neonatal cranial arteriovenous malformations. Color Doppler imaging also is helpful in assessing flow after embolic or surgical therapy.

Cerebral Angiography↗