Prefrontal cortical thinning in HIV infection is associated with impaired striatal functioning.

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 Infection Is Associated with Impaired Striatal Function during Inhibition with Normal Cortical Functioning on Functional MRI.

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.

Diagnostic yield and accuracy of paediatric image-guided fine needle aspiration biopsy of deep organ tumours.

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.

A silver bullet? The role of radiology information system data mining in defining gunshot injury trends at a South African tertiary-level hospital.

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.

HIV infection results in ventral-striatal reward system hypo-activation during cue processing.

OBJECTIVE: Functional MRI has thus far demonstrated that HIV has an impact on frontal-striatal systems involved in executive functioning. The potential impact of HIV on frontal-striatal systems involved in reward processing has yet to be examined by functional MRI. This study therefore aims to investigate the effects of HIV infection on reward processing by examining the function of the ventral-striatal reward system during a monetary incentive delay task. DESIGN: This is a cross-sectional case-control study. METHODS: Eighteen combined antiretroviral therapy-naive HIV-positive (HIV+) participants, as well as 16 matched healthy controls, performed a monetary incentive delay task. This paradigm assesses behaviour as well as functional brain activity-associated reward anticipation and reward outcome. RESULTS: HIV+ participants showed a general decrease in activation associated with both neutral as well as potentially rewarding cues in their ventral striatum. We found normal activity related to reward outcome in the orbito-frontal cortex. Despite HIV+ participants' reaction times being significantly slower when independently measured from the reward paradigm, this performance deficit normalized during the performance of the reward task. CONCLUSION: 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.