Diffusion tensor imaging indices as biomarkers for cognitive changes following paediatric radiotherapy: a systematic review and meta-analysis

Radiological Predictors of Cognitive Impairment in Paediatric Brain Tumours Using Multiparametric Magnetic Resonance Imaging: A Review of Current Practice, Challenges and Future Directions

Paediatric brain tumours and their treatments are associated with long-term cognitive impairment. While the aetiology of cognitive impairment is complex and multifactorial, multiparametric Magnetic Resonance Imaging (MRI) can identify many risk factors including tumour location, damage to eloquent structures and tumour phenotype. Hydrocephalus and raised intracranial pressure can be observed, along with risk factors for post-operative paediatric cerebellar mutism syndrome or epilepsy. MRI can also identify complications of surgery or radiotherapy and monitor treatment response. Advanced imaging sequences provide valuable information about tumour and brain physiology, but clinical use is limited by extended scanning times and difficulties in processing and analysis. Brain eloquence classifications exist, but focus on adults with neurological deficits and are outdated. For the analysis of childhood tumours, limited numbers within tumour subgroups and the investigation of long-term outcomes necessitate using historical scans and/or multi-site collaboration. Variable imaging quality and differing acquisition parameters limit the use of segmentation algorithms and radiomic analysis. Harmonisation can standardise imaging in collaborative research, but can be challenging, while data-sharing produces further logistical challenges. Consequently, most research consists of small single-centre studies limited to regional analyses of tumour location. Technological advances reducing scanning times increase the feasibility of clinical acquisition of high-resolution standardised imaging including advanced physiological sequences. The RAPNO and SIOPE paediatric brain tumour imaging guidelines have improved image standardisation, which will benefit future collaborative imaging research. Modern machine learning techniques provide more nuanced approaches for integration and analysis of the complex and multifactorial data involved in cognitive outcome prediction.

Accuracy of Radiomics in the Identification of Extrathyroidal Extension and BRAFV600E Mutations in Papillary Thyroid Carcinoma: A Systematic Review and Meta-analysis

RATIONALE AND OBJECTIVES

Extrathyroidal extension (ETE) and BRAFV600E mutation in papillary thyroid cancer (PTC) increase mortality and recurrence risk. Preoperative identification presents considerable challenges. Although radiomics has emerged as a potential tool for identifying ETE and BRAFV600E mutation, systematic evidence supporting its effectiveness remains insufficient. Therefore, this paper aims to determine the effectiveness of radiomics in detecting ETE and BRAFV600E mutations in PTC.

MATERIALS AND METHODS

PubMed, Web of Science, Cochrane, and Embase databases were searched until May 7th, 2024. The Radiomics Quality Score tool assessed bias risk. Subgroup analyses based on radiomics and clinical characteristics were conducted.

RESULTS

Our systematic review included 19 studies, encompassing 5337 PTC cases. Among these, 12 articles focused on ETE and seven articles focused on BRAFV600E mutations. For the identification of ETE in the validation set, the summarized machine learning (ML) models demonstrated 0.80c-index (95%CI: 0.77-0.83), 0.77 sensitivity (95%CI: 0.72-0.81), and 0.78 specificity (95%CI: 0.73-0.82). Radiomics based on ultrasound demonstrated 0.82c-index (95%CI: 0.78-0.86), 0.77 sensitivity (95%CI: 0.68-0.84), and 0.84 specificity (95%CI: 0.75-0.91). For the identification of BRAFV600E mutations in the validation set, the summarized ML models showed 0.80c-index (95%CI: 0.72-0.87), 0.76 sensitivity (95%CI: 0.67-0.84), and 0.88 specificity (95%CI: 0.77-0.94). ML models based on ultrasound-guided radiomics had 0.81c-index (95%CI: 0.74-0.89), 0.79 sensitivity (95%CI: 0.71-0.86), and 0.87 specificity (95%CI: 0.74-0.94).

CONCLUSION

Radiomics in identifying ETE and BRAFV600E mutation have high c-index, sensitivity, and specificity, especially images from ultrasound, demonstrating the potential for diagnosing ETE and BRAFV600E mutations in PTC.

Measuring the impact of treatment on memory functions in pediatric posterior fossa tumor survivors using diffusion tensor imaging

BACKGROUND AND PURPOSE

The aim of the present prospective exploratory study was to investigate the long-term impact of treatment on brain structure integrity and memory functions in pediatric posterior fossa tumor (PFT) survivors using diffusion tensor imaging (DTI), to determine whether the latter could provide useful biomarkers of memory impairment.

MATERIAL AND METHODS

Sixty participants were included in this study, divided into three groups: 22 irradiated PFT, 17 non-irradiated PFT, and 21 healthy controls. All underwent memory tests and multimodal MRI, including a DTI sequence. Mean diffusivity and fractional anisotropy values were extracted for bilateral brain structures involved in memory, in order to carry out between-group comparisons and calculate correlations with memory test scores and radiotherapy doses. Statistical tests were two-sided, and p values < 0.05 were considered statistically significant.

RESULTS

DTI metrics were significantly higher for irradiated PFT survivors than in non-irradiated PFT survivors and controls (p < 0.05). Memory test scores were significantly lower for PFT survivors, particularly irradiated patients (p < 0.02), and were correlated with DTI metrics. (-0.27 < r < -0.62, p < 0.04). DTI metrics were correlated with either total or maximum dose for some structures.

CONCLUSION

Preliminary results of this study point to microstructural damage in memory-related brain areas in PFT survivors, particularly in irradiated patients, and identify DTI metrics as potential biomarkers of memory deficit.

Impact of Pediatric Posterior Fossa Tumor Treatments on Working Memory Tracts Using Resting-State fMRI and Tractography

BACKGROUND AND PURPOSE

Working memory, a primary cognitive domain, is often impaired in pediatric brain tumor survivors, affecting their attention and processing speed. This study investigated the long-term effects of treatments, including surgery, radiotherapy (RT), and chemotherapy (CT), on working memory tracts in children with posterior fossa tumors (PFTs) using resting-state functional MRI (rs-fMRI) and diffusion MRI tractography.

METHODS

This study included 16 medulloblastoma (MB) survivors treated with postoperative RT and CT, 14 pilocytic astrocytoma (PA) survivors treated with surgery alone, and 16 healthy controls from the Imaging Memory after Pediatric Cancer in children, adolescents, and young adults study (NCT04324450). Working memory tracts were identified by combining seed masks from rs-fMRI maps and whole-brain tractography from diffusion MRI. Connectivity alterations were assessed qualitatively and quantitatively, alongside neuropsychological evaluations and correlations with behavioral outcomes and mean supratentorial dose.

RESULTS

Compared to controls, MB survivors exhibited significant impairments in the working memory network, including reductions in tract volume (TV), fiber density, fiber cross-section (FC), mean streamline length (MLS), and fractional anisotropy (FA) (all p = 0.04). Lower working memory scores were correlated with reduced TV and FA in MB survivors. Higher mean supratentorial doses were associated with lower TV, FC, and FA values across multiple tracts, particularly in the arcuate and superior longitudinal fasciculi.

CONCLUSIONS

Tractography-derived features highlighted white matter damage as a biomarker of treatment-related neurotoxicity in PFTs survivors. These findings underscore the detrimental impact of RT and CT on working memory networks and emphasize the importance of preserving cognitive function during treatment planning.

Using diffusion MRI to understand white matter damage and the link between brain microstructure and cognitive deficits in paediatric medulloblastoma patients

PURPOSE

Survivors of medulloblastoma face a range of challenges after treatment, involving behavioural, cognitive, language and motor skills. Post-treatment outcomes are associated with structural changes within the brain resulting from both the tumour and the treatment. Diffusion magnetic resonance imaging (MRI) has been used to investigate the microstructure of the brain. In this review, we aim to summarise the literature on diffusion MRI in patients treated for medulloblastoma and discuss future directions on how diffusion imaging can be used to improve patient quality.

METHOD

This review summarises the current literature on medulloblastoma in children, focusing on the impact of both the tumour and its treatment on brain microstructure. We review studies where diffusion MRI has been correlated with either treatment characteristics or cognitive outcomes. We discuss the role diffusion MRI has taken in understanding the relationship between microstructural damage and cognitive and behavioural deficits.

RESULTS

We identified 35 studies that analysed diffusion MRI changes in patients treated for medulloblastoma. The majority of these studies found significant group differences in measures of brain microstructure between patients and controls, and some of these studies showed associations between microstructure and neurocognitive outcomes, which could be influenced by patient characteristics (e.g. age), treatment, radiation dose and treatment type.

CONCLUSIONS

In future, studies would benefit from being able to separate microstructural white matter damage caused by the tumour, tumour-related complications and treatment. Additionally, advanced diffusion modelling methods can be explored to understand and describe microstructural changes to white matter.

Remote assessment of cognition and quality of life following radiotherapy for nasopharyngeal carcinoma: deep-learning-based predictive models and MRI correlates

PURPOSE

Irradiation of the brain regions from nasopharyngeal carcinoma (NPC) radiotherapy (RT) is frequently unavoidable, which may result in radiation-induced cognitive deficit. Using deep learning (DL), the study aims to develop prediction models in predicting compromised cognition in patients following NPC RT using remote assessments and determine their relation to the quality of life (QoL) and MRI changes.

METHODS

Seventy patients (20-76 aged) with MRI imaging (pre- and post-RT (6 months-1 year)) and complete cognitive assessments were recruited. Hippocampus, temporal lobes (TLs), and cerebellum were delineated and dosimetry parameters were extracted. Assessments were given post-RT via telephone (Telephone Interview Cognitive Status (TICS), Telephone Montreal Cognitive Assessment (T-MoCA), Telephone Mini Addenbrooke's Cognitive Examination (Tele-MACE), and QLQ-H&N 43). Regression and deep neural network (DNN) models were used to predict post-RT cognition using anatomical and treatment dose features.

RESULTS

Remote cognitive assessments were inter-correlated (r > 0.9). TLs showed significance in pre- and post-RT volume differences and cognitive deficits, that are correlated with RT-associated volume atrophy and dose distribution. Good classification accuracy based on DNN area under receiver operating curve (AUROC) for cognitive prediction (T-MoCA AUROC = 0.878, TICS AUROC = 0.89, Tele-MACE AUROC = 0.919).

CONCLUSION

DL-based prediction models assessed using remote assessments can assist in predicting cognitive deficit following NPC RT. Comparable results of remote assessments in assessing cognition suggest its possibility in replacing standard assessments.

IMPLICATIONS FOR CANCER SURVIVORS

Application of prediction models in individual patient enables tailored interventions to be provided in managing cognitive changes following NPC RT.

Barriers to the use of Methylphenidate in Pediatric Neuro-oncology Services

BACKGROUND

Survivors of childhood CNS tumors are at a significant risk of chronic and multifaceted neurocognitive late effects. Recent findings indicate the potential utility of methylphenidate in addressing neurocognitive and academic plateauing and improving quality-of-life outcomes in this clinical population. However, the prescription of methylphenidate in neuro-oncology services remains inconsistent.

OBJECTIVE

To explore the neurocognitive assessment and rehabilitative interventions (including the use of methylphenidate) offered to survivors of childhood CNS tumors within mainland UK.

METHOD

We used a semi-structured questionnaire to gather qualitative data from clinical psychologists and neuropsychologists within National Health Service pediatric neuro-oncology principal treatment centers (PTCs) during May 2018. Thematic analytical methods were used to explore themes within the collected data.

RESULTS

Eleven (58%) of the 19 PTCs returned the completed questionnaire. Respondents reported inadequate resource of psychology in many pediatric neuro-oncology PTCs, which limited the provision of methylphenidate to a restricted proportion of the patient group (i.e., those with the most profound neurocognitive difficulties). Respondents reported an interest in exploring the utility of methylphenidate in their patient group yet described a lack of appropriate evidence of its efficacy. In addition, respondents highlighted the need for the provision of accessible research summaries and treatment protocols addressing the use of methylphenidate.

CONCLUSION

We anticipate that national collaboration between clinicians and researchers working in the cancer survivorship field will support the advancement of interventions such as methylphenidate for the growing clinical population of survivors of childhood CNS tumors.

Role of resting-state functional MRI in detecting brain functional changes following radiotherapy for head and neck cancer: a systematic review and meta-analysis

PURPOSE

Increasing evidence implicates changes in brain function following radiotherapy for head and neck cancer as precursors for brain dysfunction. These changes may thus be used as biomarkers for early detection. This review aimed to determine the role of resting-state functional magnetic resonance imaging (rs-fMRI) in detecting brain functional changes.

METHODS

A systematic search was performed in the PubMed, Scopus, and Web of Science (WoS) databases in June 2022. Patients with head and neck cancer treated with radiotherapy and periodic rs-fMRI assessments were included. A meta-analysis was performed to determine the potential of rs-fMRI for detecting brain changes.

RESULTS

Ten studies with a total of 513 subjects (head and neck cancer patients, n = 437; healthy controls, n = 76) were included. A significance of rs-fMRI for detecting brain changes in the temporal and frontal lobes, cingulate cortex, and cuneus was demonstrated in most studies. These changes were reported to be associated with dose (6/10 studies) and latency (4/10 studies). A strong effect size (r = 0.71, p < 0.001) between rs-fMRI and brain changes was also reported, suggesting rs-fMRI's capability for monitoring brain alterations.

CONCLUSION

Resting-state functional MRI is a promising tool for detecting brain functional changes following head and neck radiotherapy. These changes are correlated with latency and prescription dose.