Application of new MR techniques in pediatric patients

Discrimination of paediatric brain tumours using apparent diffusion coefficient histograms

OBJECTIVE

To determine if histograms of apparent diffusion coefficients (ADC) can be used to differentiate paediatric brain tumours.

METHODS

Imaging of histologically confirmed tumours with pre-operative ADC maps were reviewed (54 cases, 32 male, mean age 6.1 years; range 0.1-15.8 years) comprising 6 groups. Whole tumour ADC histograms were calculated; normalised for volume. Stepwise logistic regression analysis was used to differentiate tumour types using histogram metrics, initially for all groups and then for specific subsets.

RESULTS

All 6 groups (5 dysembryoplastic neuroectodermal tumours, 22 primitive neuroectodermal tumours (PNET), 5 ependymomas, 7 choroid plexus papillomas, 4 atypical teratoid rhabdoid tumours (ATRT) and 9 juvenile pilocytic astrocytomas (JPA)) were compared. 74% (40/54) were correctly classified using logistic regression of ADC histogram parameters. In the analysis of posterior fossa tumours, 80% of ependymomas, 100% of astrocytomas and 94% of PNET-medulloblastoma were classified correctly. All PNETs were discriminated from ATRTs (22 PNET and 4 supratentorial ATRTs) (100%).

CONCLUSIONS

ADC histograms are useful in differentiating paediatric brain tumours, in particular, the common posterior fossa tumours of childhood. PNETs were differentiated from supratentorial ATRTs, in all cases, which has important implications in terms of clinical management. Key Points • MR based apparent diffusion coefficient histograms can help differentiate paediatric brain tumours • ADC histogram parameters correctly classified the great majority of posterior fossa tumours.

Basic and translational neonatal neuroscience research: whither goest the future of physician-scientists?

OBJECTIVES

In light of declining numbers of physician-scientists, the goal of this project was to identify strategies to invigorate and attract new talent to clinical research in the field of pediatric neurosciences.

DESIGN

To develop a broad perspective, a program of direct questions was addressed to both US and non-US physicians at all stages of career development.

RESULTS

Respondents identified numerous promising avenues of research but also indicated obstacles to research progress at all stages of career development including medical students, resident physicians, junior medical faculty, mid-career faculty, and senior faculty. At each career stage, ideas were offered to attract resources for, build prestige for, and motivate commitment for participation in clinical research.

CONCLUSIONS

Creative promotion of clinical research at all stages of medical education and career development offers great promise to expand current physician-scientist numbers, and thereby stimulate many exciting advances in medicine.

Diffusion-weighted MR imaging: pediatric clinical applications

We have summarized the diffusion-weighed imaging (DWI) findings in a number of different cerebral disorders. In many cases, DWI with the accompanying apparent diffusion coefficient (ADC) map provides additional useful information to the standard imaging sequences. Pathophysiologic mechanisms resulting in baseline normal ADC values and changes with disease processes are not well understood; therefore, caution should be used when prognosticating the outcome of regions with abnormal ADCs. DWI should be used as an adjunct to routine imaging and interpreted in the context of the routine imaging findings and clinical scenario. As our understanding of ADC mechanisms increases and we begin to incorporate information about tissue organization from diffusion tensor imaging or diffusion spectrum imaging, the role of these methods in clinical diagnosis should continue to increase.

Imaging the Developing Epileptic Brain

Accurate identification of cortical malformations in children with epilepsy can be crucial for successful clinical management. Although standard head-coil magnetic resonance imaging (MRI) at 1.5 tesla (T) can be used to view the macrostructure of the brain, phased array technology at both 1.5 and 3T significantly improves signal-to-noise ratio (SNR). As a result, spatial resolution and contrast can be optimized to increase visual detection of subtle macrostructural changes that occur with small epileptogenic lesions. In addition, these improvements in SNR allow more accurate quantitative analysis of brain macrostructure and more accurate assessment of brain microstructure using newer sophisticated imaging techniques. For example, phased array imaging enables more accurate diffusion tensor imaging (DTI), and 3T imaging, when combined with phased array technology, enables more informative diffusion spectroscopic imaging (DSI). Recent technological improvements therefore result in improved lesion detection and enable assessment of cerebral growth trajectories and associated longitudinal changes in tissue microstructural organization that occur in association with various types of epilepsy. This article presents a brief comparison of imaging techniques currently in use, both clinically and experimentally, to diagnose, treat, and increase our understanding of the neuropathology of epilepsy in the developing brain.

Imaging for neuro-ophthalmic and orbital disease

PURPOSE

To provide an update on imaging of the brain and orbit for ophthalmologists.

DESIGN

Literature review.

METHODS

A systematic English-language medline search and summary of recent literature on imaging of brain and orbit was performed.

RESULTS

Computed tomography and magnetic resonance (MR) scanning are the mainstays for the evaluation of most disorders involving the brain and orbit. Computed tomography angiography and magnetic resonance angiography are relatively newer applications that are useful for the evaluation of arterial and venous disorders. Special sequences such as fat suppression and fluid attenuation inversion recovery are useful techniques for specific ophthalmic indications. Diffusion weighted imaging and perfusion-weighted imaging are improving the evaluation of acute stroke. Functional MRI, positron emission tomography scanning and single photon emission computed tomography may provide useful information regarding brain or tumor metabolism. Magnetic resonance spectroscopy has expanded our knowledge of brain function. Newer imaging studies have improved our diagnostic abilities on many fronts, including new sequences, new applications of imaging studies, and functional imaging of brain.

CONCLUSION

New imaging techniques for brain and orbit have an increased potential for improving diagnostic yield. Accurate and timely communication with the neuroradiologist can optimize the prescription and interpretation of imaging in ophthalmology.