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At least 541 records · Page 30Linked to original sources
PubMed2002

[A clinical observation on variation of crossed disparity and uncrossed disparity in intermittent exotropia].

OBJECTIVE: To understand the clinical variety of crossed disparity and uncrossed disparity in intermittent exotropia. METHODS: Zero disparity stereo-acuity, crossed disparity and uncrossed disparity stereo-acuity of 55 cases with intermittent exotropia were examined with stereogram designed by Yan Shaoming before surgery. RESULTS: In group 1 consisting of 25 cases, the zero disparity stereo-acuity of normal persons was 48%, the values of crossed disparity and uncrossed disparity stereoacuity were not in the normal range, and the crossed disparity was larger than the uncrossed disparity stereo-acuity (t = 843.5, P < 0.000 1). In group 2 including 26 cases, the zero disparity stereo-acuity of normal person was 30.8%, the value of crossed disparity was abnormal, and the uncrossed disparity was not found. In group 3 consisting of 4 cases, only the abnormal zero disparity stereo-acuity was found. In the 55 cases, there was no coexistence of zero disparity and uncrossed disparity, no existence of only crossed disparity or only uncrossed disparity, and no coexistence of crossed and uncrossed disparity. CONCLUSIONS: (1) In the cases with intermittent exotropia, the zero disparity stereoacuity, the crossed disparity and uncrossed disparity stereoacuities are abnormal. (2) The sequential damage of stereopsis in intermittent exotropia is uncrossed disparity, crossed disparity and zero disparity. (3) It is proved in the clinic that the binocular temporal retinae correspond to the crossed disparity and the binocular nasal retinae correspond to the uncrossed disparity.

Adolescent↗
PubMed1995

In-hospital mortality for surgical repair of congenital heart defects: preliminary observations of variation by hospital caseload.

OBJECTIVE: To examine the impact of hospital caseload on in-hospital mortality for pediatric congenital heart surgery. DESIGN: Population-based, retrospective cohort study. SETTING: Acute care hospitals in California and Massachusetts. PATIENTS: Children undergoing surgery for congenital heart disease, identified by the presence of procedure codes indicating surgical repair of a congenital heart defect in computerized statewide hospital discharge abstract databases. Cases were grouped into four categories based on the complexity of the procedure. MAIN OUTCOME MEASURES: Adjusted odds ratios (OR) for in-hospital death were estimated using generalized estimating equations that account for the intra-institutional correlation among patients. RESULTS: A total of 2833 cases at 37 centers were identified. Compared with centers performing > 300 cases per year, after controlling for patient characteristics, centers performing < 10 cases per year had an OR for in-hospital death of 7.7 (95% confidence interval (CI) [1.6-37.8]); 10 to 100 cases, OR = 2.9 (95% CI [1.6-5.3]); 101 to 300 cases, OR = 3.0 (95% CI [1.8-4.9]). Independent risk factors for mortality included procedure complexity category (P < .0001), use of cardiopulmonary bypass (P < .0001), young age at surgery (P = .001), and transfer from another acute care hospital (P < .0001). Few differences were found by hospital caseload in length of stay or total hospital charges. CONCLUSIONS: For children with a congenital heart defect who underwent surgery in California in 1988 or Massachusetts in 1989, the risk of dying in-hospital was much lower if the surgery was performed at an institution performing > 300 cases annually. This study was limited by the absence of clinical detail in discharge abstract databases. If these findings are corroborated by other studies, health care delivery strategies that direct children requiring surgical correction of congenital heart defects to high-volume centers may substantially reduce overall mortality.

California↗
PubMed2006

Consistency in electronic portal imaging registration in prostate cancer radiation treatment verification.

BACKGROUND: A protocol of electronic portal imaging (EPI) registration for the verification of radiation treatment fields has been implemented at our institution. A template is generated using the reference images, which is then registered with the EPI for treatment verification. This study examines interobserver consistency among trained radiation therapists in the registration and verification of external beam radiotherapy (EBRT) for patients with prostate cancer. MATERIALS AND METHODS: 20 consecutive patients with prostate cancer undergoing EBRT were analyzed. The EPIs from the initial 10 fractions were registered independently by 6 trained radiation therapist observers. For each fraction, an anterior-posterior (AP or PA) and left lateral (Lat) EPIs were generated and registered with the reference images. Two measures of displacement for the AP EPI in the superior-inferior (SI) and right left (RL) directions and two measures of displacement for the Lat EPI in the AP and SI directions were prospectively recorded. A total of 2400 images and 4800 measures were analyzed. Means and standard deviations, as well as systematic and random errors were calculated for each observer. Differences between observers were compared using the chi-square test. Variance components analysis was used to evaluate how much variance is attributed to the observers. Time trends were estimated using repeated measures analysis. RESULTS: Inter-observer variation expressed as the standard deviation of the six observers' measurements within each image were 0.7, 1.0, 1.7 and 1.4 mm for APLR, APSI, LatAP and LatSI respectively. Variance components analysis showed that the variation attributed to the observers was small compared to variation due to the images. On repeated measure analysis, time trends were apparent only for the APLR and LatSI measurements. Their magnitude however was small. CONCLUSION: No clinically important systematic observer effect or time trends were identified in the registration of EPI by the radiation therapist observers in this study. These findings are useful in the documentation of consistency and reliability in the quality assurance of treatment verification of EBRT for prostate cancer.

Diagnostic Imaging↗
PubMed2000

Accuracy and validity of stereology as a quantitative method for assessment of human temporal lobe volumes acquired by magnetic resonance imaging.

The object of this study was to compare the accuracy and validity of stereology as a method for determining whole temporal lobe volume with the more established technique of semi-automated thresholding and tracing. Ten, fixed, post-mortem human brains, were imaged using a three dimensional (3D) acquisition protocol. The volume of the left temporal lobe, dissected from each brain, was determined by fluid displacement. Each volume was compared to measurements obtained from magnetic resonance images (MRI) of the post-mortem brain using each of the two segmentation methods. Post-acquisition processing was performed using MEASURE software. Three investigators performed each measurement three times using each method, yielding a total of 180 measurements. Stereology took, on average, half the time of thresholding/tracing. Using a clinically acceptable variation for 95% of repeat measures; both intra-observer and inter-observer variation were acceptable for each technique. However, validity, as demonstrated by graphs of agreement against water displacement showed that the "limits of agreement" using stereology were within the acceptable range, while those using the thresholding/tracing technique were not. Quantitative estimates of variation and a graphical representation of the limits of agreement show that stereology is at least as precise as the thresholding/tracing method but is superior in terms of speed and validity. This has broad implications for published estimates of brain region volumes in human diseases such as epilepsy, dementia and other neurodegenerative disorders.

Aged↗