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Biomedical subjects

M A Sargent

Publications and source records attributed to M A Sargent.

At least 19 recordsLinked to original sources
PubMed2000

What is the normal prevalence of vesicoureteral reflux?

BACKGROUND: The prevalence of vesicoureteral reflux in normal children has been estimated to be 0.4% to 1.8%. Based on epidemiological data, it can be estimated that 2.2% of girls and 0.6% of boys may be found to have reflux as a result of the investigation of urinary tract infection. This implies that most children with reflux will develop urinary tract infection. However, most children with reflux detected by screening do not develop infection. Hence the prevalence of vesicoureteral reflux in normal children may be higher than the previous estimates. OBJECTIVE: To determine the prevalence of vesicoureteral reflux in groups of children with different clinical indications for cystogram. MATERIALS AND METHODS: Over 250 articles from the literature were reviewed to determine the prevalence of vesicoureteral reflux in children undergoing cystogram. Means and 95% confidence limits were derived from the data in studies that met the inclusion criteria. RESULTS: The prevalence of vesicoureteral reflux in children with urinary tract infection was 31.1% (95% CI: 29.9-32.8). The prevalence of vesicoureteral reflux varied between patient groups, but often approached or exceeded the prevalence in urinary tract infection. The prevalence in normal kidneys was 17.2% (95% CI: 14.4-20.1). CONCLUSION: Vesicoureteral reflux is common in nearly all patient groups examined. The prevalence of vesicoureteral reflux in normal children is probably significantly higher than the traditional estimates.

Adolescent↗
PubMed1999

Application of a three-point method for water-fat MR imaging in children.

BACKGROUND: Effective fat suppression is desirable in clinical magnetic resonance imaging. Conventional frequency selective fat suppression is dependent on accurate prescan shimming and is subject to artifacts due to magnetic field inhomogeneity. Quadrature three-point water-fat imaging with direct phase encoding is an alternative technique for fat suppression that has been previously described in adult volunteers and patients. OBJECTIVE: To evaluate the use of three-point water-fat imaging with direct phase encoding for fat-suppressed MR scans in children. MATERIALS AND METHODS: Sixty-two three-point water-fat imaging studies were performed in 55 children 2 months to 18 years old. T 1-weighted fat-suppressed (water) images from this sequence were compared with frequency selective fat-suppressed images obtained in 15 patients. The reliability and subjective quality of the sequence were assessed in the remaining 47 cases. RESULTS: High-quality fat suppression was achieved in all anatomic sites studied, even where frequency selective fat-suppression failed due to magnetic susceptibility artifact. The three-point water-fat sequence was visually preferred to the frequency selective fat saturation technique in 15/15 cases. CONCLUSION: Three-point water-fat imaging has replaced the conventional frequency selective technique for fat suppression on T 1-weighted MR imaging at our institution.

Adipose Tissue↗
PubMed1999

Atelectasis on pediatric chest CT: comparison of sedation techniques.

BACKGROUND: A change in practice at our institution resulted in increased use of anesthesia for CT scan of the chest in children who required sedation. OBJECTIVE: To determine whether there is a difference in the frequency or severity of pulmonary atelectasis on CT scan in children sedated by anesthesiologists compared with children sedated by radiologists using intravenous pentobarbital. MATERIALS AND METHODS: Retrospective blinded review of 60 CT scans of the chest performed in 41 children. Forty-one studies in children sedated by radiologists (median age 29 months) were compared with 19 studies in children sedated by anesthesiologists (median age 25 months). RESULTS: Atelectasis sufficient to obscure pulmonary metastases was shown in 5 of 41 (12 %) radiology sedations and 13 of 19 (68 %) anesthesiology sedations (P < 0.01). Higher grades of atelectasis were recorded in children under anesthesia (P < 0.01). CONCLUSION: Atelectasis is more frequent and more severe in children undergoing general anesthesia compared with intravenous pentobarbital sedation. Consideration should be given to the use of forced inspiration in children anesthetized for CT scan of the chest.

Anesthesiology↗
PubMed1998

Speech, cognition, and imaging studies in congenital ocular motor apraxia.

Detailed neurological, speech and language, psychological, and neuroimaging studies were carried out in eight children with the diagnosis of congenital ocular motor apraxia. The neurological examination showed clinical evidence of cerebellar vermis abnormality (hypotonia and truncal ataxia) in all cases. Neuroimaging studies suggested that the site of neuropathological disturbance of congenital ocular motor apraxia was the inferior vermis. Half of the subjects had associated speech apraxia. The most likely location of brain disturbance, which was responsible for the speech apraxia, was also an as yet undefined area of the vermis. Psychological testing consistently revealed visual-spatial difficulties. These may have been secondary to cerebellar pathology or to developmentally inappropriate sensory input caused by the abnormal saccades. Children with speech apraxia appear to be slightly more affected neurologically than those with normal speech.

Apraxias↗
PubMed1997

Fast fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging of the brain: a comparison of multi-shot echo-planar and fast spin-echo techniques.

PURPOSE: To evaluate fast spin-echo and multi-shot echo-planar fluid-attenuated inversion recovery (FLAIR) sequences in paediatric brain imaging. MATERIALS AND METHODS: Matched images from 32 patients with suspected tumour or white matter disease were independently evaluated by two paediatric neuroradiologists. The observer preferences for image quality and lesion detection were analysed for differences between fast spin-echo FLAIR and multi-shot echo-planar FLAIR. Diagnostic quality was compared with that of fast spin-echo T2-weighted images. RESULTS: Images of a diagnostic quality equivalent to that of fast spin-echo T2-weighted images were achieved with both FLAIR techniques. Grey and white matter differentiation and cerebrospinal fluid (CSF) nulling were significantly better on fast spin-echo FLAIR sequences. CSF flow artefact was reduced on multi-shot echo-planar FLAIR. There was no difference in lesion detection. Fast spin-echo FLAIR images were visually preferred at the expense of longer imaging time. CONCLUSION: Fast FLAIR techniques are complementary to fast spin-echo T2-weighted sequences in imaging of the paediatric brain. We find that the fast spin-echo FLAIR sequence is preferable to the multi-shot echo-planar technique.

Brain↗
PubMed1997

Interobserver variation in the sonographic estimation of renal volume in children.

OBJECTIVE: To quantify the interobserver variability in the sonographic estimation of renal volume in children. MATERIALS AND METHODS: Three observer pairs measured the lengths and diameters of 176 kidneys in 90 children. Renal volumes were estimated from the formula for a prolate ellipsoid. The mean and standard deviation of the absolute and percentage differences between observers were calculated. The 95 % limits of agreement for each pair of observers were derived. Log-transformed data were used to derive overall limits of agreement. RESULTS: Absolute interobserver variation increased with renal volume. Percentage variation was independent of renal size. There is a 95 % probability that a measurement of renal volume by one observer will be between 0.69 and 1.44 times a measurement made by a different observer. CONCLUSION: The interobserver variation in the sonographic estimation of renal volume represents approximately 2-3 years' normal growth in children aged over 2 years.

Adolescent↗
PubMed1997

Basal ganglia infarction associated with HHV-6 infection.

A 6 year old boy presented with meningoencephalitis and was found to have serological evidence of acute human herpes virus-6 (HHV-6) infection. He did not develop symptomatic seizures or the rash of exanthum subitum (roseola). His course was marked by severe spastic quadriparesis associated with radiological evidence of basal ganglia infarction. HHV-6 infection should be considered in any child with acute meningoencephalitis.

Acute Disease↗
PubMed1995

Obstructive lung disease in children after allogeneic bone marrow transplantation: evaluation with high-resolution CT.

OBJECTIVE: Obstructive lung disease is a major complication of bone marrow transplantation related to graft-versus-host disease. The purpose of this study was to determine the usefulness of high-resolution CT to evaluate obstructive lung disease occurring in children after bone marrow transplantation. MATERIALS AND METHODS: Ten high-resolution CT scans of the lungs were obtained in seven children who developed chronic obstructive lung disease after bone marrow transplantation. All seven patients had chronic graft-versus-host disease. Spirometry, the gold standard test, confirmed airflow obstruction in each case, five prior to high-resolution CT. Two patients were too young to have spirometry until 10 and 15 months respectively after successful high-resolution CT. Selected images from these studies were randomized with similar images from five control subjects and reviewed blindly. All images from scans in patients with obstructive lung disease were analyzed retrospectively for parenchymal hypoattenuation, bronchial dilatation, bronchial wall thickening, and abnormal parenchymal opacity. Expiratory air-trapping was assessed on cine high-resolution CT done in four cases. RESULTS: Three blinded observers each correctly identified all five controls among 15 high-resolution CT examinations. No scan from a patient with obstructive lung disease was considered normal. Areas of parenchymal hypoattenuation affected 35 of 35 lobes of the lung. Expiratory air-trapping was shown by cine high-resolution CT. Subsegmental or segmental bronchial dilatation was seen in 23 of 25 lobes in five patients. Bronchial wall thickening was not a prominent feature. Increasing abnormality was demonstrated in three patients on follow-up high-resolution CT. The high-resolution CT abnormalities were similar to those reported in patients with bronchiolitis obliterans. CONCLUSION: High-resolution CT of the lungs can show extensive abnormality in children who develop chronic obstructive lung disease after bone marrow transplantation. High-resolution CT is a useful noninvasive technique in the evaluation of this disease.

Adolescent↗
PubMed1995

Voiding cystourethrography in children with urinary tract infection: the frequency of vesicoureteric reflux is independent of the specialty of the physician requesting the study.

OBJECTIVE: The purpose of this study was to determine if the frequency of vesicoureteric reflux on voiding cystourethrography in children with a history of urinary tract infection varies according to the specialty of the physician requesting the examination. MATERIALS AND METHODS: The study included 309 children (192 girls, 117 boys) with a history of urinary tract infection who had their first voiding cystourethrogram. The median age at first voiding cystourethrogram in boys was 12 months; in girls, it was 48 months. The reports of these examinations were retrospectively reviewed, and the presence of vesicoureteric reflux was recorded. The age and sex distribution of children referred for voiding cystourethrography by pediatric urologists and nephrologists (subspecialists) was compared with the age and sex distribution of children referred by pediatricians, family practitioners, and adult urologists (other clinicians). The rate of detection of vesicoureteric reflux was calculated according to age and sex. Ages studied were younger than 1 year, younger than 2 years, 2-4 years, and 5 years or older. The frequency of vesicoureteric reflux in children referred by subspecialists was compared with the frequency in children referred by other clinicians, allowing for the age and sex of the children. RESULTS: The sex distribution of children referred for voiding cystourethrography was similar for subspecialists and other clinicians. More children younger than 2 years old were referred by other clinicians than by subspecialists. Vesicoureteric reflux was found in 30% of boys and 29% of girls. The frequency of reflux in boys did not change with age. The frequency of reflux in girls 5 years or older (15%) was less than in younger girls. We found no significant difference between the rates of reflux in boys and girls within the age groups examined. The overall rate of detection of reflux in patients referred by subspecialists (30%) was almost the same as that in patients referred by other clinicians (29%). We also found no difference in the frequency of reflux in children referred by subspecialists compared with children referred by other clinicians after allowing for the age and sex of the children. CONCLUSION: In children with a history of urinary tract infection, the rate of detection of vesicoureteric reflux on voiding cystourethrography is independent of the specialty of the physician requesting the examination.

Adolescent↗
PubMed1994

Obstructive lung disease in children after allogeneic bone marrow transplantation.

Obstructive lung disease (OLD) has been described as a significant complication after allogeneic bone marrow transplantation (BMT). The incidence of OLD in adults appears to be low (approximately 3%), but there is little data for children. We analyzed 89 consecutive pediatric allogeneic BMTs, > or = 1.5 years post-BMT, performed at British Columbia's Children's Hospital from 1980 to 1992 for evidence of OLD. Diagnosis of OLD was based on clinical findings (nonproductive cough, wheezing, and dyspnea with no evidence of infection), pulmonary function tests (FEV1 < 80% and FEF25-75% < 60% predicted), lung biopsy, and computed tomography scan. Sixty-seven of the 89 children evaluated survived > or = 90 days and were classified as at risk for OLD. Thirteen of 67 (19.4%), developed OLD, 3 of which were transient. The development of OLD was strongly associated with the following high-risk groups: chronic graft-versus-host disease (GVHD) (37.1% OLD), increased donor age, acute GVHD, and either mismatched related or matched unrelated donor transplants. No correlation was found with methotrexate prophylaxis for GVHD, total body irradiation, or cytomegalovirus reactivity in either donor or recipient and the development of OLD. Further analysis of only children with chronic GVHD showed that liver involvement by GVHD before the onset of OLD (57.9%) was the only other significant predictive factor. We observed an overall increased prevalence of OLD in children compared with that previously reported in adults. Further studies are required to confirm whether age is a risk factor for development of OLD after allogeneic BMT.

Acute Disease↗
PubMed1994

Plain abdominal radiography in suspected intussusception: a reassessment.

The objectives of the study were (1) to determine the interobserver variation in interpretation of abdominal radiographs in children with clinically suspected intussusception, and (2) to determine the diagnostic value of abdominal radiographs in these patients. One hundred and eighty-two plain abdominal radiographic examinations (AXR) performed in children with clinically suspected intussusception were reviewed blind to the clinical history and findings of air enema. The presence or absence of nine AXR signs relevant to intussusception was documented. Each AXR was categorized as equivocal, positive or negative for intussusception, with the aim of achieving no false negatives. Interobserver variation in the identification of AXR signs and radiologic diagnoses was calculated using the kappa statistic for 60 cases assessed independently by three observers. Using the findings of air enema as gold standard, the prevalence of AXR signs in all patients with (60) and without (122) intussusception was determined and their diagnostic values calculated. The best observer agreement was for the presence of sparse small bowel gas (supine, k = 0.68) and the worst for the presence of cecal gas (erect, k = 0.18). All three observers agreed intussusception to be present or absent in only 7 of 60 cases and the majority agreement was equivocal in more than half. Overall agreement between observers for the diagnosis of intussusception was k = 0.30. The best positive predictors of intussusception were the soft tissue mass and sparse large bowel gas, with likelihood ratios of 3.9 and 2.5. Cecal feces predicted against intussusception, likelihood ratio 0.11. AXR was equivocal in 53%, positive in 21% and negative in 26%. Where a firm radiographic diagnosis was made, the diagnostic accuracy of AXR was 84%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Sonographic measurement of relative renal volume in children: comparison with scintigraphic determination of relative renal function.

OBJECTIVE: Observer error in the sonographic estimation of renal volume in children has not been reported. Knowledge of the possible magnitude of error is important in assessing abnormalities of renal growth. This study was undertaken to determine the error of sonographic measurements of relative renal volume by comparing them with measurements of relative renal function from 99mTc-dimercaptosuccinic acid (DMSA) scintigraphy. MATERIALS AND METHODS: The study included 52 children, 2 months to 16 years old, who had DMSA scintigraphy and renal sonography on the same day. The sonographic and scintigraphic studies were interpreted independently. Relative function of the right kidney as shown by DMSA scintigrams in the direct posterior view was compared with relative volume as determined with sonography. Renal volumes were calculated by using the formula for a prolate ellipsoid. The standard deviation of the differences (SDD) between relative renal function and relative renal volume was calculated, and the limits of agreement were derived. RESULTS: Thirty-three children had normal renal morphology on both studies. Twenty-five kidneys in 19 children were abnormal on one or both studies, including 14 definitely scarred kidneys in 12 children. Relative function of the right kidney in patients with normal kidneys was 50.1 +/- 2.5%, including one possible outlying value. Normal relative volume of the right kidney was 49.1 +/- 3.1%. In patients with normal kidneys, the difference between relative function and relative volume of the right kidney was 1.0 +/- 2.8% with 95% limits of agreement of 6.7% and -4.7%. Agreement between relative function and relative volume was worse for children with abnormal kidneys; the mean difference was 2.0%, and the largest observed difference was 10.9%. Correlation between relative renal volume and relative renal function for all patients was high (r = .94), with 95% limits of agreement of 8.6% and -5.8%. CONCLUSION: The agreement between relative renal function and relative renal volume was good. In children with normal kidneys, estimated relative renal volume derived from sonography can be expected to lie within 6.7% of the relative renal function determined scintigraphically.

Adolescent↗