Not Dandy Walker variant: a review of prominent retrocerebellar CSF space in children

The prominent retrocerebellar cerebrospinal fluid (CSF) space can be frequently encountered on paediatric neuroimaging studies. In cases involving abnormal vermian development where imaging does not align with the established criteria of Dandy-Walker malformation (DWM), the term "Dandy-Walker variant or continuum" has been historically employed to describe the aberrant posterior fossa development. Instead, the emphasis is on a more elaborate description of the findings in the posterior fossa. Moreover, combining the findings in the supratentorial brain can occasionally predict certain neurogenetic disorders that mimic Dandy-Walker phenotype. The present review demonstrates and differentiates the imaging features of various entities that result in an enlarged retrocerebellar CSF space, such as inferior vermian hypoplasia (IVH) and several neurogenetic conditions.

The paediatric thymus: recognising normal and ectopic thymic tissue

The appearance of the paediatric thymus changes as the normal process of thymic involution occurs. Thymic tissue may be orthotopic within the anterior mediastinum or ectopically located along the course of its embryological development. The variable appearance of orthotopic and ectopic thymic tissue in children on imaging studies may lead to misinterpretation of the normal thymus as pathology. Recognition of normal thymic tissue can mitigate unnecessary further diagnostic testing and patient anxiety. In this review, we discuss the embryological development and anatomical variants of normal thymus, and demonstrate the multimodality imaging features of the normal thymus in children, including positron-emission tomography, and diffusion-weighted imaging and in- and opposed-phase imaging on magnetic resonance imaging. We demonstrate the normal thymus mimicking pathological processes and discuss features that distinguish normal thymus, including thymic rebound hyperplasia, from pathology.

Racial differences in responses to interferon-beta-1a in chronic hepatitis C unresponsive to interferon-alpha: a better response in Chinese patients

Re-treatment with interferon-alpha alone for chronic hepatitis C nonresponders to interferon-alpha monotherapy is almost ineffective. This multicentre, randomized, parallel-group, dose-finding study evaluated the efficacy of interferon-beta-1a in the treatment of chronic hepatitis C patients unresponsive to interferon-alpha. A total of 267 patients were randomized to one of four groups: subcutaneous interferon-beta-1a 12 MIU (44 microg) or 24 MIU (88 microg) administered three times weekly or daily. Patients were treated for 48 weeks and then followed up for an additional 24 weeks. There was a trend towards a dose-response relationship regarding virological [loss of detectable serum hepatitis C virus (HCV) RNA] and biochemical response (normalization of serum alanine aminotransferase). Overall, 22 patients (8.3%) had a virological response at the end of treatment; nine patients (3.4%) had a sustained virological response (SVR). Strikingly, 21.7% (5/23) of Chinese patients achieved SVR. Univariate analysis revealed that race was the only variable related to SVR [odds ratio (OR) 16.6; 95% CI 4.1-67.3; P < 0.0001]. Multiple logistic regression analysis also confirmed that more Chinese patients achieved SVR than non-Chinese patients (OR 12.3; 95% CI 2.6-59.3; P = 0.0017). In addition, complete clearance of HCV-RNA occurred earlier in Chinese than in non-Chinese responders (median 2 vs 30 weeks; P = 0.020). Thirty-six patients were withdrawn from treatment because of adverse events. Most adverse events were mild or moderate in severity. In conclusion, interferon-beta-1a provided considerable clinical benefit in Chinese patients with chronic hepatitis C unresponsive to interferon-alpha. The evaluation of interferon-beta-1a in this setting is progressing.