BACKGROUND AND PURPOSE: To our knowledge, there has been no study that compares the radiation dose delivered to the eye lens by 16-and 64-section multidetector CT (MDCT) for standard clinical neuroimaging protocols. Our aim was to assess radiation-dose differences between 16-and 64-section MDCT from the same manufacturer, by using near-identical neuroimaging protocols.
Summary: Purpose:The clinical utility of hippocampal volumetry is well documented, but the materials and techniques required to perform the procedure are not widely available outside major research centers. We describe a personal computer-based method of volumetric data analysis.Methods: Using a 1.0-T scanner, we obtained 2-mmthick tilted coronal MPRAGE magnetic resonance imaging (MRI) scans of 20 healthy volunteers aged 20-38 years.We used an inexpensive utility program to extract image information and an NIH Image for image analysis. The hippocampal formations were traced with a graphics tablet and landmarks described by Watson et al. (Neurology 1992;42:1743-50). Overlays of individual observers' tracings were used to fine tune the selection of landmarks and boundaries. Filled-in silhouette pairs generated from these "training tracings" were compared to determine how well observers could visually quantify area differences.Mesial temporal lobe epilepsy (MTLE) is a Surgically remediable epilepsy syndrome. Unilateral hippocampal atrophy is a sensitive and specific indicator of MTLE. Studies validating the usefulness of magnetic resonance imaging (MRI) include those correlating hippocampal cell loss with extent of atrophy (1-3), surgical outcome ( 4 3 , with hippocampal asymmetry and neuropsychological performance in relation to extent of hippocampal atrophy (1,6). Although qualitative assessment of the hippocampus allows a trained eye to detect asymmetry reliably, quantitative volumetry is useful for research and is reportedly more sensitive (7). Making meaningful assessment of minimal to moderate bilateral volume loss is difficult without using volumetric techniques.On the other hand, hippocampal volumetry is time- Results: Visual detection of asymmetry of silhouette pairs was sensitive, but the magnitude of asymmetry was underestimated. We achieved intraobserver coefficients of variation of right/left volume ratios between 0.82 and 3.16 and an interobserver range of volume ratios of 6%. In 20 healthy controls aged 20-38 years, the mean right and left hippocampal volumes were 2,911 mm3 and 2,836 mm3, respectively. The lower limits of normal were 2,217 mm3 for the right and 2,178 mm3 for the left. The mean right/ left hippocampal ratio was 1.03, and the limits of normal (3 SD) for this were 0.95 to 1.10.Conclusions: Hippocampal volumetry can be performed reliably and economically. Our methodology makes it possible for different observers to generate consistent and comparable measurements.
Introduction: Functional magnetic resonance imaging (fMRI) is a neuroradiological technique for the localisation of cortical function. FMRI made its debut in cognitive neuroscience and then eventually to other clinical applications. We report our experience with pre-surgical fMRI on a high field scanner, based purely on a clinical platform. Materials and Methods: The protocols included motor, auditory, visual and language fMRI. The choice of protocols was dependant on clinical request and lesion locale. Results: Retrospective analysis and audit of the first 30 consecutive patients over a 12-month period revealed that about 85% of patients had a successful examination. In a pictorial essay, we demonstrate that patients with weakness in performing a motor task showed abnormal activations of the pre-motor and supplementary motor areas. Conclusion: FMRI data greatly enhances the pre-surgical planning process and the conduct of surgery when it is incorporated into the surgical navigation system in the operating theatre. Key words: fMRI, Pre-surgical planning, Task activation
Introduction: We evaluated the accuracy of endorectal magnetic resonance imaging (MRI) in the staging of prostate cancer. Materials and Methods: We retrospectively reviewed 32 patients who underwent endorectal MR prostate prior to radical prostatectomy. The tumour stage based on MR imaging was compared with the pathologic stage. The sensitivity and specificity of endorectal MR prostate in the evaluation of extracapsular extension (ECE) of the tumour were then determined. Results: MR correctly diagnosed 17 cases of organ-confined prostate carcinoma and 2 cases of locally advanced disease. In the evaluation of ECE, endorectal MR achieved a high specificity of 94.4%, low sensitivity of 14.3% and moderate accuracy of 59.4%. Conclusion: Endorectal MR prostate has high specificity for the detection of ECE. It is useful in the local staging of prostate cancer in patients with intermediate risk as this helps to ensure that few patients will be deprived of potentially curative surgery.
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