FDG–PET. A possible prognostic factor in head and neck cancer

Previous studies have shown that high uptake of 18F-fluoro-2-deoxy-glucose in head and neck cancer, as determined by the standardized uptake value on positron emission tomography scan, was associated with poor survival. The aim of this study was to confirm the association and to establish whether a high standardized uptake value had prognostic significance. Seventy-three consecutive patients with newly diagnosed squamous cell carcinoma of the head and neck underwent a positron emission tomography study before treatment. Age, gender, performance status tumour grade, stage, maximal tumour diameter and standardized uptake value were analyzed for their possible association with survival. The median standardized uptake value for all primary tumours was 7.16 (90% range 2.30 to 18.60). In univariate survival analysis the cumulative survival was decreased as the stage, tumour diameter and standardized uptake value increased. An standardized uptake value of 10 was taken as a cut-off for high and low uptake tumours. When these two groups were compared, an standardized uptake value >10 predicted for significantly worse outcome (P=0.003). Multivariate analysis demonstrated that an standardized uptake value >10 provided prognostic information independent of the tumour stage and diameter (P=0.002). We conclude that high FDG uptake (standardized uptake value>10) on positron emission tomography is an important marker for poor outcome in primary squamous cell carcinoma of the head and neck. Standardized uptake value may be useful in distinguishing those tumours with a more aggressive biological nature and hence identifying patients that require intensive treatment protocols including hyperfractionated radiotherapy and/or chemotherapy

Diffusion MR imaging: clinical applications.

International audienceWater self-diffusion, a recently discovered source of contrast on MR images, has already shown promise for some clinical applications. Most studies have been of the brain, essentially for technical reasons. Diffusion is useful in distinguishing the different components of brain tumors (cystic regions, edema, necrosis) from the tumor core itself. Recent studies have shown that diffusion is anisotropic in brain white matter (i.e., dependent on the fiber tract's orientation in space), offering new insights into myelin disorders. Diffusion is also dramatically altered in the minutes following ischemic injury in the cat brain, which may have tremendous impact for the diagnosis and management of hyperacute stroke. With ultrafast acquisition schemes, diffusion imaging has also been used outside the CNS, for instance, in the eye and kidney. Future applications include diffusion-localized spectroscopy and temperature imaging. This article reviews recent progress in this field and suggests potential applications

MR color mapping of myelin fiber orientation.

International audienceDiffusion of water in brain white matter has been shown to be anisotropic: Water mobility is lower when measured perpendicular to the fiber direction rather than parallel to it. This feature was used to produce images of the myelin fiber orientation. Coronal and sagittal MR diffusion images were obtained in volunteers using an echo-planar imaging sequence sensitized to molecular diffusion in perpendicular directions. Color-coded images of myelin orientation were then generated by combining these images together. The orientation of the white matter tracts was found to be in excellent agreement with known anatomy. Myelin fiber orientation mapping may offer a new perspective to evaluate white matter disorders

Diffusion and perfusion magnetic resonance imaging in brain tumors.

International audienceThe article reviews recent progress made in the field of diffusion and perfusion magnetic resonance (MR) imaging and presents possible applications in brain tumors. Diffusion, a new parameter, provides useful data to assess tissue structure and function. Perfusion MR imaging gives results that are somewhat similar to those obtained with classic non-MR imaging methods, but it offers several potential advantages

Diffusion and perfusion magnetic resonance imaging in brain tumors.

International audienceThe article reviews recent progress made in the field of diffusion and perfusion magnetic resonance (MR) imaging and presents possible applications in brain tumors. Diffusion, a new parameter, provides useful data to assess tissue structure and function. Perfusion MR imaging gives results that are somewhat similar to those obtained with classic non-MR imaging methods, but it offers several potential advantages

Proton magnetic resonance spectroscopic imaging in the clinical evaluation of patients with Niemann-Pick type C disease

OBJECTIVES—10 patients with Niemann-Pick disease type C (NP-C) were studied by proton magnetic resonance spectroscopic imaging (1H-MRSI) to assess the biochemical pathology of the brain and to determine whether this method can be useful to clinically evaluate these patients.
METHODS—1H-MRSI permits the simultaneous measurement of N-acetyl aspartate (NA), compounds containing choline (Cho), creatine plus phosphocreatine (Cre), and lactate (Lac) signal intensities from four 15 mm slices divided into 0.84 ml single volume elements. Spectroscopic voxels were identified from seven regions of interest.
RESULTS—In patients with NP-C, NA/Cre was significantly decreased in the frontal and parietal cortices, centrum semiovale, and caudate nucleus; Cho/Cre was significantly increased in the frontal cortex and centrum semiovale. Significant correlations were found between clinical staging scale scores and 1H-MRSI abnormalities.
CONCLUSION—1H-MRSI showed diffuse brain involvement in patients with NP-C consistent with the pathological features of the disease. 1H-MRSI is an objective and sensitive tool to neurologically evaluate patients with NP-C.