Background: There is little published research on the wide variation of corpus callosum (CC) morphology in children, the assessment of which is made difficult by the complex alteration of its appearance in childhood. Objective: The purpose of our study was to assess the morphology of the CC on mid-sagittal T1- weighted magnetic resonance imaging (MRI) in a large number of children and correlate the findings with demographic and clinical criteria. Materials and methods: We reviewed all brain mid-sagittal T1-weighted MRI’s performed from July to December 2015 and obtained relevant demographic and clinical information from the accompanying report and laboratory system. The CC morphology was analysed by three radiologists and compared using cross tabulation with the chi-square test and ANOVA. Interobserver correlation was assessed using Kappa coefficient of conformance. Results: 257 patients with mean age 72±60 months were included, 142 were male (55%). In abnormal MRI’s the CC was less likely to have an identifiable isthmus and was more likely to be convex, thin and have separation of the fornix insertion (all p<0.01). In young children (< 5 years) the CC was also less likely to have an identifiable isthmus (p=0.01) and was more likely to be convex (p=0.04) but the fornix was more likely to insert normally (p<0.01). Children with tuberous sclerosis had significantly thinner splenia (p=0.02). Conclusion: There is a distinct pathological appearance of the CC. The immature appearance of the corpus callosum can mirror this but is distinguished by normal insertion of the fornix and normal quantitative measurements. Splenial thinning in children with tuberous sclerosis warrants further investigation.

Background: Seizures are a frequent and potentially significant presenting complaint to the emergency department (ED). Determining the underlying cause for seizures is important in guiding further clinical management of patients. ED physicians at Groote Schuur Hospital, Cape Town, South Africa routinely request Computed Tomography (CT) brain scans in the work-up of patients presenting with first onset seizures. Objectives: To determine the number and proportion of CT scan examinations with abnormal findings in patients presenting with first onset seizures at the Groote Schuur Hospital ED, Cape Town, South Africa and to identify the range of CT abnormalities. Method: A retrospective study was carried out in the Division of Radiology, Groote Schuur Hospital. Patients who presented to the ED with first onset seizures and who underwent brain CT examination as part of their work up between 1 January 2013 and 31 December 2016 were enrolled. All patients presenting to the ED with first onset focal or grand mal seizures were included. Patients with recent trauma and those with previously diagnosed epilepsy were excluded. Results: A total of 200 patients were eligible for the study. Of these, 92 (46%) patients with first onset seizures had an abnormality or abnormalities on brain CT scan. Of those patients whose HIV status was known, 50% of HIV positive and 53% of HIV negative patients had abnormal CT scans. 54% of patients with focal seizures and 38% with generalised seizures had an abnormality on CT scan. Abnormalities found on CT scans included chronic cerebral infarction (7.5%), acute or subacute cerebral infarction (4.5%), neurocysticercosis (7.0%), other infections (6.5%), haemorrhage and other vascular lesions (6.5%), post-traumatic encephalomalacia (6.5%), primary brain tumours and metastases (based on CT characteristics) (7.0%). Conclusion: Forty-six (46%) of patients presenting to the Groote Schuur Hospital ED, Cape Town, South Africa with first onset seizures had an abnormality on their brain CT scans. Brain CT scan is therefore recommended in patients presenting to the ED department with first-onset seizures, irrespective of their HIV/ neurological status.

INTRODUCTION: The question of when and if to perform follow- up CT scanning of the brain in a patient with a proven head injury remains pertinent, and the answer is not clear cut. This is even more so compounded when one tries to compare and equate what happens in a developed country with that of a developing country such as South Africa. AIM: To evaluate referral patterns, associated time-delays and findings of follow-up CT as well as patient outcomes in patients with head injury at Groote Schuur Hospital. METHOD: A retrospective review, over a 6 month time period, of the CT scans and folders belonging to patients who underwent follow-up CT scanning of the brain after blunt trauma to the head. RESULTS: There were 313 follow-up studies performed in 212 patients, of which the majority, 135 /313 (43.1%) were referred for neurological reasons, whilst 103/313 (32.9%) were referred for conservative management reasons and 75/313 (24%) were referred as part of their post-surgical check-up. There were significant time delays from arrival of patients in casualty to their initial CT scan (mean 18.74 hours) as well as between the initial CT and the first follow-up scan (mean 121.78 hours). There was a significant amount of data missing regarding the time of actual injury for many patients. There were 74 neurosurgical interventions that took place as a result of CT scans performed. Of these, 54 (73%) took place after the initial CT scan, whilst only 20 (27%) occurred after a follow-up CT. Of those surgical interventions performed after a follow- up study, 6 (30%) were performed as a result of a scan performed for post-surgical check- up. 12 (60%) were performed as a result of a scan performed for neurological reasons. Two (10%) neurosurgical interventions occurred as a result of a scan performed for conservative management reasons (thus routine follow-up imaging). CONCLUSIONS: A routine single follow-up CT may be a reasonable approach with further follow-up imaging reserved for patients who have undergone surgery, those with possibly surgically manageable findings on initial CT (that do not undergo surgery) and those with new neurology. The routine use of follow-up CT beyond the first follow-up CT is unlikely to lead to a change in management when the above clinical, and prior CT findings are absent. However, the time delays across all aspects of imaging traumatic brain injuries in our setting are unpredictable and represent a major problem in standardising when CT scans are performed.

Background: Nodular thyroid disease is common worldwide, and the incidence of thyroid nodules is increasing globally. Ultrasound (US)-guided thyroid nodule fine needle aspiration biopsy (FNAB) is a reliable and cost-effective method of distinguishing between benign and malignant nodules before major surgery is performed. Aims: The study aimed to establish the diagnostic yield of US-guided thyroid FNAB's done at Groote Schuur Hospital over two years and to correlate findings with histopathological results in those patients that underwent thyroidectomy. Objectives: The objectives were to establish the number of US-guided FNABs performed, the number of repeat FNABs and the number of patients who subsequently had thyroidectomy over two years. A further objective was to evaluate the diagnostic yield by comparing the cytology and histology results for patients that underwent thyroidectomy. Methods: This was a retrospective study of all patients referred for US-guided FNAB from 1 January 2018 to 31 December 2019. All patients with cytology results after FNAB and histology results after thyroidectomy, were included in the study. US-guided FNAB data was collected from the Picture Archiving and Communication System (PACS) and Radiology Information System (RIS), while cytology and histology data were obtained from the National Health Laboratory Services (NHLS). Results: A total of 236 patients were included in the study (220 females and 16 males), with ages ranging from 19 to 82 years. The diagnostic yield was 34-% on the first, 36-% on the second and 48-% on the third FNAB. Most of the US-guided FNABs were non-diagnostic (66- % on the first, 64-% on the second and 52-% on the third FNAB). A total of 107 patients (45 %) had a repeat FNAB, while 23 patients (9.7-%) had a second repeat FNAB. A total of 48 patients (20.3-%) underwent thyroidectomy. Cancer was detected in 29/236 (12.3-%), of which 17/29 (59-%) were papillary thyroid carcinomas. There was no significant correlation between FNAB results and post-surgical histopathological results in patients who underwent thyroidectomy, with a p value of .15. Conclusion: The overall cancer rate of 12.3-% was comparable with that of other institutions. 66-% of US-guided FNABs were non-diagnostic, while 34-% were diagnostic on the first FNAB with 45-% requiring a repeat second FNAB. The assistance of a cytopathologist during the biopsy has been known to result in fewer non-diagnostic results, avoiding repeat attempts. Further diagnostic and cost-effective analysis of cytopathology assistance in the US-guided FNAB for characterising thyroid nodules is advised.

Carotid cavernous fistula (CCF) is an abnormal connection between the carotid artery and the cavernous sinus. The CCF's are usually classified in three ways: 1. Pathologically, as spontaneous or traumatic; 2. Hemodynamically, into high-flow or low-flow; or 3. Angiographically, as direct or indirect. The Barrow angiographic classification is most commonly used. It is based on the pattern of arterial supply and has therapeutic implications.

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [273]-288).

When applying cognitive diagnostic models, the goal is to accurately estimate students’ diagnostic profiles. The accuracy of these estimates may be enhanced by looking at the types of incorrect options a student selects. This thesis research examines the additional diagnostic information available from the distractors in multiple-choice items used in large-scale achievement assessments and identifies optimal conditions for extracting diagnostic information. The study is based on the analyses of both real student responses and simulated data. The real student responses are from a large-scale provincial math assessment for grade 6 students in Ontario. Data were then simulated under different skill dimensionality and item discrimination conditions. Comparisons were made between student profile estimates when using the DINA and MC-DINA models. The MC-DINA model is a newly developed cognitive diagnostic model where the probability of a student choosing a particular item option depends on how closely the student’s cognitive skill profile matches the skills tapped by that option. The results from the simulation data analysis suggested that when the simulated data included additional diagnostic information in the distractors, the MC-DINA model was able to use that information to improve the estimation of the student profiles, which shows the utility of the additional information obtained from item distractors. The value of adding information from distractors was greater when there was lower item discrimination and more skill multidimensionality. However, in the real data, the keyed options provided more diagnostic information than the distractors, and there was little information in the distractors that could be utilized by the MC-DINA model. This implies that current math test items could be further developed to include diagnostically rich distractors. The study offers some suggestions for a design of multiple-choice test items and its formative use.

When applying cognitive diagnostic models, the goal is to accurately estimate students’ diagnostic profiles. The accuracy of these estimates may be enhanced by looking at the types of incorrect options a student selects. This thesis research examines the additional diagnostic information available from the distractors in multiple-choice items used in large-scale achievement assessments and identifies optimal conditions for extracting diagnostic information. The study is based on the analyses of both real student responses and simulated data. The real student responses are from a large-scale provincial math assessment for grade 6 students in Ontario. Data were then simulated under different skill dimensionality and item discrimination conditions. Comparisons were made between student profile estimates when using the DINA and MC-DINA models. The MC-DINA model is a newly developed cognitive diagnostic model where the probability of a student choosing a particular item option depends on how closely the student’s cognitive skill profile matches the skills tapped by that option. The results from the simulation data analysis suggested that when the simulated data included additional diagnostic information in the distractors, the MC-DINA model was able to use that information to improve the estimation of the student profiles, which shows the utility of the additional information obtained from item distractors. The value of adding information from distractors was greater when there was lower item discrimination and more skill multidimensionality. However, in the real data, the keyed options provided more diagnostic information than the distractors, and there was little information in the distractors that could be utilized by the MC-DINA model. This implies that current math test items could be further developed to include diagnostically rich distractors. The study offers some suggestions for a design of multiple-choice test items and its formative use.

Thèse d'exercice : Médecine. Médecine générale : Paris 12 : 2006. / Titre provenant de l'écran-titre. Bibliogr. f. 53-56.

xi, 56 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Image processing is a powerful tool for increasing the reliability and reproducibility of disease diagnostics. In the hands of pathologists, image processing provides quantitative data from histological images which supplement the qualitative data currently used by specialists. This thesis presents a novel method for analyzing digitized images of hematoxylin and eosin (H&E) stained histology slides to detect and quantify inflammatory polymorphonuclear leukocytes to aid in the grading of acute inflammation of the placenta as an example of the use of image processing in aid of diagnostics. Methods presented in this thesis include segmentation, a novel threshold selection technique and shape analysis. The most significant contribution is the automated color threshold selection algorithm for H&E stained histology slides which is the only unsupervised method published to date. / Committee in charge: Dr. John Conery, Chair; Dr. Matthew J. Sottile