The publication of this book is timely. Although diffusion-weighted imaging is routinely available on most modern clinical MRI machines there are few resources that even approach a comprehensive evaluation in clinical practice. Whilst it was generally accepted that a diffusion-weighted abnormality represented irreversible ischaemia in the setting of acute stroke, subsequent work has shown that this tissue may be pathologically heterogenous and can even be reversible. This understanding is slowly filtering into books describing imaging in stroke. This book introduces the principles of diffusionweighted imaging, normal findings and, importantly, pitfalls and artefacts, the latter chapter being extremely helpful. There is then a chapter dedicated to the differentiation between cytotoxic and vasogenic oedema. The book then sequentially discusses infarction, haemorrhage, vasculopathies, epilepsy, demyelination, metabolic diseases, infection, trauma, neoplasia and paediatrics. All of these discussions are comprehensive and very well illustrated with numerous examples. One of the novelties of the book is the final section entitled ‘how to use this book’. This basically does the reverse of the previous chapters in that it is based primarily on the differences seen with the diffusionweighted image, the apparent diffusion coefficient (ADC) image and the T2 image, i.e., it discusses the differential diagnosis of an image, e.g., with increased diffusion weighting, low ADC and increased T2. This section is likely to be of great assistance to individuals seeing a combination of signal changes for the first time. There are very few negative points associated with the book, areas such as mislabelling of some of the figures in Chapter 14 which should have been picked up by the publisher. Overall the authors should be complimented for putting together such a rich resource of cases in such a balanced manner. The book is very accessible and will mainly be of interest to radiologists involved in reporting diffusion-weighted studies and should be a welcome addition to the reading room area for reference. There will be other individuals within clinical neuroscience who will also find the book of interest.

Diffusion-weighted MR Imaging of the brain

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Otimização da anisotropia fronto-calosa e ressonância magnética [1,5T] no idoso normal e com risco cérebro-vascular

RESUMO: Objetivos – Determinar a sensibilidade e especificidade das ponderacoes Difusao (DWI) e T2 Fluid-Attenuated Inversion Recovery (FLAIR) na avaliacao de lesoes da substância branca (SB) e verificar em que medida se complementam, por forma a criar um conjunto de boas praticas na RM cranioencefalica de rotina. Metodologia – Recorrendose a uma metodologia quantitativa, efetuou-se uma analise retrospetiva da qual foram selecionados 30 pacientes, 10 sem patologia e 20 com patologia (2 com EM, 7 com Leucoencefalopatia, 6 com doenca microangiopatica e 5 com patologia da substância branca indefinida). Obteve-se uma amostra de 60 imagens, nomeadamente: 30 imagens ponderadas em DWI e 30 em T2 FLAIR. Recorrendo ao programa Viewdex®, tres observadores avaliaram um conjunto de imagens segundo sete criterios: visibilidade, detecao, homogeneidade, localizacao, margens e dimensoes da lesao e capacidade de diagnostico. Com os resultados obtidos recorreu-se ao calculo de sensibilidade e especificidade pelas Curvas ROC, bem como a analise estatistica, nomeadamente, Teste-T, Indice de Concordância Kappa e coeficiente de correlacao de Pearson entre as variaveis em estudo. Resultados – Os resultados de sensibilidade e de especificidade obtidos para a ponderacao T2 FLAIR foram superiores (0,915 e 0,038, respetivamente) aos da ponderacao DWI (0,08 e 0,100, respetivamente). Nao se verificaram variâncias populacionais significativas. Obteve-se uma elevada correlacao linear entre as variaveis com um valor r situado entre 0,8 e 0,99. Verificou-se tambem uma variabilidade consideravel entre os observadores. Conclusoes – Dados os baixos valores de sensibilidade e especificidade obtidos para a DWI, sugere-se que esta deva ser incluida no protocolo de rotina de crânio como auxiliar no diagnostico diferencial com outras patologias. Palavras-chave: DWI, T2 FLAIR, ressonância magnetica, lesoes da substância branca. White matter lesions by magnetic resonance: an assessment between DWI and T2 FLAIR techniques

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Lesões da substância branca por ressonância magnética: uma avaliação entre as ponderações DWI e T2 FLAIR

Aims – To assess the potential of magnetic resonance spectroscopy (1H‑MRS) in the diagnostic of degenerative disease of the lumbar disc and to advocate the adding of this technique in the classification of the invertebral disc involution vs degeneration (L4‑L5 and L5‑S1) in the clinical routine of lumbar pain status, not related with mechanic causes. Material and method – We studied 102 out of 123 lumbar intervertebral discs. The distribution among spaces was 61 discs at L4‑L5, 41 at L5‑S1 level and 34 at D12‑L1 level. The magnetic resonance studies were performed using a 1.5 T scan-ner. A single‑voxel Point Resolved Spectra Selection (PRESS) technique was used. The ratios [Lac/Nacetyl], [Nacetyl/(Lac+Lip)] and additionally the resonance of lipids were applied to evaluate the biochemistry of the discs, its involution, disc disruption and eventual susceptibility to initiate degeneration process. The ratios and the lipidic value of L4‑L5‑S1 discs were ascertained with the different behavior of D12‑L1. Furthermore, the comparison between L4‑L5, L5‑S1 and D12‑L1 discs was performed according with rating in T2 weighted (adjusted scale 1‑4 from Pfirrmann1 criteria). Results – Related to D12‑L1, the ratios and the lipids of L4‑L5‑S1 discs are statistically different. When used as a complementary of conventional T2 weighted, they have a good discrimination in the all degrees of disc involution vs degeneration. The ratio [Lac/Nacetyl] at L4‑L5‑S1 level was increased when compared to D12‑L1 (p=0.033 for disks with [1+2] score of involution and p=0.004 for disks with score [3+4]). These results suggest that disc degeneration vs involution in higher degrees defines a decrease in the lactate’s peak. The ratio [Nacetyl/(Lac+Lip)] provides a good discrimination of involution between scores [1+2] and [3+4] at L4‑L5 level, presenting the values of the ratios (mean 0.65 and 0.5 with p=0.04). The mean ratio of [Nacetyl/(Lac+Lip)] in the L4‑L5 disc was 1.8 times higher than that of L1‑D12. The lipid spectrum at L4‑L5‑S1 in the higher scores showed no constant prevalence in the resonance frequencies. Conclusion – The (1H) spectroscopy of intervertebral discs may contribute with a supplementary semiology to the conventional MRI. The resonances of L4‑L5 and L5‑S1 discs, involuted or degenerated, must be related with D12‑L1, which are more stable and have lower likelihood of disc degeneration.

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Maria Margarida Ribeiro

Papers

Lesões da substância branca por ressonância magnética: uma avaliação entre as ponderações DWI e T2 FLAIR

Espetroscopia (1H) por ressonância magnética do disco intervertebral lombar no adulto e sua aplicação na rotina imagiológica