The aim of the present study was to investigate the effect of HIV infection on cortical and subcortical regions of the frontal-striatal system involved in the inhibition of voluntary movement. Functional MRI (fMRI) studies suggest that human immunodeficiency virus (HIV) infection is associated with frontostriatal dysfunction. While frontostriatal systems play a key role in behavioral inhibition, there are to our knowledge no fMRI studies investigating the potential impact of HIV on systems involved during the inhibition of voluntary movement. A total of 17 combined antiretroviral therapy (cART) naïve HIV+ participants as well as 18 age, gender, ethnic, education matched healthy controls performed a modified version of the stop-signal paradigm. This paradigm assessed behavior as well as functional brain activity associated with motor execution, reactive inhibition (outright stopping) and proactive inhibition (anticipatory response slowing before stopping). HIV+ participants showed significantly slower responses during motor execution compared to healthy controls, whereas they had normal proactive response slowing. Putamen hypoactivation was evident in the HIV+ participants based on successful stopping, indicating subcortical dysfunction during reactive inhibition. HIV+ participants showed normal cortical functioning during proactive inhibition. Our data provide evidence that HIV infection is associated with subcortical dysfunction during reactive inhibition, accompanied by relatively normal higher cortical functioning during proactive inhibition. This suggests that HIV infection may primarily involve basic striatal-mediated control processes in cART naïve participants.
While cortical thinning has been associated with HIV infection, it is unclear whether this reflects a direct effect of the virus, whether it is related to disruption of subcortical function or whether it is better explained by epiphenomena, such as drug abuse or comorbid medical conditions. The present study investigated the relationship between cortical thickness and subcortical function in HIV+ patients. Specifically, we examined the relationship between prefrontal cortical thickness and striatal function. Twenty-three largely treatment naïve, non-substance abusing HIV+ participants and 19 healthy controls matched for age, gender, and educational status were included. Cortical morphometry was performed using FreeSurfer software analysis. Striatal function was measured during an fMRI stop-signal anticipation task known to engage the striatum. Any cortical regions showing significant thinning were entered as dependent variables into a single linear regression model which included subcortical function, age, CD4 count, and a measure of global cognitive performance as independent predictors. The only cortical region that was significantly reduced after correction for multiple comparisons was the right superior frontal gyrus. Striatal activity was found to independently predict superior frontal gyral cortical thickness. While cortical thinning in HIV infection is likely multifactorial, viral induced subcortical dysfunction appears to play a role.
HIV caused a decrease in activity during cue processing in the ventral striatum, with normal cortical functioning during reward outcome processing. Our results therefore suggest that HIV not only has an impact on fronto-striatal systems involved in executive functioning, but also has a direct impact on the function of the ventral-striatal reward system.
Background: Paediatric tumour cytological diagnosis by image-guided fine needle aspiration biopsy (FNAB) with rapid on-site evaluation (ROSE) has not gained wide acceptance despite increasing publications advocating the procedure.Objective: The primary aim was an audit of the diagnostic yield and accuracy of paediatric image-guided FNAB with ROSE at a single institution. Evaluation of safety was a secondary aim.Method: Details of consecutive cases of paediatric image-guided FNAB with ROSE for suspected non-benign deep-seated lesions performed from 01 January 2014 to 30 April 2020 were retrieved from the institutional radiology and laboratory databases. Diagnostic yield and accuracy were evaluated using clinico-pathological-radiological correlation and/or subsequent histological specimen diagnosis correlation. Complications and the frequency of key radiological features potentially affecting yield and accuracy were described.Results: Of 65 cases retrieved, cytology showed malignancy in 52, benign features in five and one indeterminate diagnosis; seven samples were insufficient for cytological assessment. Of the 65 cases, 58 had subsequent formal histological diagnosis. The overall diagnostic yield was 98.5%, with 94.5% sensitivity, 100.0% specificity, 100.0% positive predictive value, 75.0% negative predictive value and 95.3% diagnostic accuracy. All cases (n = 26) demonstrating restricted diffusion on MRI yielded adequate samples and cyto-histopathological correlation.Conclusion: Paediatric image-guided FNAB with ROSE has a relatively high diagnostic yield, sensitivity, specificity, positive predictive value and accuracy in the diagnosis of deep-seated tumours. The relatively low negative predictive value may reflect insufficient samples obtained from cystic and/or benign lesions. Sampling from areas of restricted MRI diffusion may enhance diagnostic yield.
Background: South Africa (SA) has no national injury surveillance system, and hence, non-fatal gunshot injuries are not routinely recorded. Most firearm-related injuries require multi-detector computer tomography (MDCT) assessment at a tertiary-level facility. MDCT scanning for victims with gunshot injuries thus provide an indication of the societal burden of firearm trauma. The potential of the modern radiology information system (RIS) to serve as a robust research tool in such settings is not fully appreciated.Objective: The aim of this study was to evaluate the use of institutional RIS data in defining MDCT scanning trends for gunshot victims presenting to a tertiary-level SA hospital.Method: A single-institution, retrospective, comparative study was conducted at the Tygerberg Hospital (TBH) Trauma Unit for the years 2013 and 2018. Using data-mining software, customised RIS searches for information on all gunshot-related emergency computed tomography scans in the respective years were performed. Demographic, temporal, anatomical and scan-protocol trends were analysed by cross tabulation, Chi-squared and Fisher’s exact tests.Results: Gunshot-related emergency MDCT scans increased by 62% (546 vs. 887) from 2013 to 2018. Lower-limb CT angiography was the commonest investigation in both periods. A higher proportion of victims in 2018 sustained thoracic injuries (12.5% vs. 19.8%; p 0.01) and required imaging of more than two body parts (13.1% vs. 19.2%; p 0.01).Conclusion: By using RIS data to demonstrate the increasing gunshot-related MDCT workload in the review period, as well as a pattern of more complex and potentially life-threatening injury, this study highlights the burden of firearm trauma in the society and the potential role of the modern RIS as a robust research tool.
To the Editor: The evasive response of Apffelstaedt et al. [1] with regard to the actual mammographic reporting methodology that forms the basis of their research [2] highlights concerns reflected in our letter [3] and raises clinical, ethical and scientific questions. Apffelstaedt et al. need to explain exactly how they, as clinicians, independently report Tygerberg Hospital mammograms when their only access to the required digital reporting monitors is at a joint weekly meeting with radiologists, in the Division of Radiodiagnosis, at which time reports already generated by radiologists are reviewed.
[1] analysed 16 105 mammograms performed at Tygerberg Hospital (TBH), Cape Town, South Africa (SA), between 2003 and 2012. The summary reported that 'mammograms were read by experienced breast surgeons' , while the discussion stated: ' A further noteworthy fact is that this TBH series was based exclusively on mammography interpretation by surgeons with a special interest in breast health. ' The suggestion that mammograms were exclusively interpreted by breast surgeons does not reflect the mammography workflow at our institution.Throughout the review period, same-day reporting of all TBH mammograms was done by senior radiology registrars working under the supervision of consultant radiologists; the latter were solely responsible for sign-off of the final mammography report.All mammograms were reviewed at a weekly multidisciplinary meeting between radiologists and our colleagues in the breast clinic. If there was consensus that a radiology report required modification, this was done by way of an addendum, written by the duty radiology registrar and attached to the original report, without changing the report itself. Addenda were required in a small minority of cases, as reflected in the TBH mammography records. Our breast clinic colleagues loaded all radiology reports onto their MS Access database during the weekly multidisciplinary meetings.Since June 2009, when TBH converted to a digital imaging platform, all mammography reporting has been on 5-megapixel diagnostic monitors, in keeping with international quality assurance requirements. TBH's two 5 megapixel monitors are in the mammography unit in the Division of Radiodiagnosis. The only time breast surgeons have access to these monitors is during their weekly review of cases at the multidisciplinary meetings with radiologists. [1] commenting on our article requires clarification that at the same time is instructive on the delivery of medical care and education in a developing country such as SA. 'Developing country' supposes an upward trajectory of improving services. However, changes in political circumstances often have a profound and disruptive effect on service delivery. Richard Pitcher[2]As a long-serving member of the TBH staff, JA wishes to aquaint the above esteemed colleagues with events that predate their arrival or specialisation at TBH. Political changes in SA in the mid-1990s resulted in an exodus of specialists from the public sector, leaving the Department of Radiology at TBH with only two consultant positions filled over several years; especially in mammography, there was no effective supervision by a consultant radiologist for a long period. In southern Africa the lack of educational resources, particularly in mammography, is well documented, [3] and under these conditions guidance of junior staff and reporting in mammography suffered even further. At the same time, mammographers delivered excellent breast imaging, and the first mammography certificate course was started at TBH in 1999. As Head of the Breast Clinic, JA was engaged in a number...
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