Development and aging of the cerebrum: assessment with proton MR spectroscopy.

BACKGROUND AND PURPOSE: MR spectroscopy allows the noninvasive evaluation of in vivo brain metabolites. Our purpose was to use this technique to assess metabolic alterations in the human cerebrum during growth, maturation, and aging. METHODS: Ninety normal human brains in subjects aged 4 to 88 years were examined with multivoxel proton MR spectroscopy. Spectra were obtained from specific voxels of 2.5 cm3 in the gray and white matter of the centrum semiovale. The ratios of N-acetylaspartate (NAA) to choline (Cho) were calculated to describe age-dependent alterations in cerebral metabolites. RESULTS: White matter NAA/Cho ratios showed rapid growth during the first decade and reached a maximum value in the second or early third decade, followed by a steady decline starting in the latter half of the third decade. The maximum peak ages for NAA/Cho were 21.9, 17.6, and 15.9 years (mean, 18.5 years) for the anterior, middle, and posterior white matter, respectively. A significant cerebral laterality of the white matter NAA/Cho was found in male subjects during development. The growth spurt and age-related decline of the white matter NAA/Cho were steeper in male than in female subjects. In contrast, the gray matter NAA/Cho showed a gradual decline with age. CONCLUSION: Proton MR spectroscopy shows significant regional and sex differences in the level of cerebral metabolites during the process of growth, maturation, and aging. This technique may play an important role in clinical applications for various conditions of metabolic disorders of the human brain.

Low-cost soft-copy display accuracy in the detection of pulmonary nodules by single-exposure dual-energy subtraction: comparison with hard-copy viewing.

This study endeavored to clarify the usefulness of single-exposure dual-energy subtraction computed radiography (CR) of the chest and the ability of soft-copy images to detect low-contrast simulated pulmonary nodules. Conventional and bone-subtracted CR images of 25 chest phantom image sets with a low-contrast nylon nodule and 25 without a nodule were interpreted by 12 observers (6 radiologists, 6 chest physicians) who rated each on a continuous confidence scale and marked the position of the nodule if one was present. Hard-copy images were 7 x 7-inch laser-printed CR films, and soft-copy images were displayed on a 21-inch noninterlaced color CRT monitor with an optimized dynamic range. Soft-copy images were adjusted to the same size as hard-copy images and were viewed under darkened illumination in the reading room. No significant differences were found between hard- and soft-copy images. In conclusion, the soft-copy images were found to be useful in detecting low-contrast simulated pulmonary nodules.

Comparison between computer-aided diagnosis and radiologists: assessment of pulmonary blood flow on chest radiographs.

To evaluate the performance of a computer-aided diagnosis (CAD) scheme for estimating increased pulmonary blood flow on chest radiographs, we compared computerized assessment with findings by radiologists. Our CAD scheme extracts selectively linear opacities corresponding to vessels in regions of interest (ROIs) in the right upper and lower lung zones on digitized chest radiographs, and then calculates a radiographic index as a physical measure that reflects the area of the extracted opacities in selected ROIs. As a measure of increased pulmonary blood flow, the upper/lower radiographic index ratio was calculated for each patient. Seven radiologists estimated the degree of increased pulmonary blood flow for the same images of ROI sets presented on a cathode-ray tube monitor in a randomized order. Between the normal-pulmonary capillary wedge pressure (PCWP) group and increased-PCWP groups, there was no significant difference in performance between CAD and radiologists (p = 0.105). However, when the normal and mild PCWP groups were compared, the performance of CAD was superior to that of radiologists (p = 0.001). This study indicates that our CAD scheme is promising for quantitative estimation of increased pulmonary blood flow, especially in mild cases.

Computerized radiographic assessment of pulmonary blood flow in patients with and those without mitral stenosis.

The authors investigated whether a computerized analysis system can be used with chest radiography for estimating the redistribution of pulmonary blood flow in patients with and those without mitral stenosis (MS). Their system uses four-directional Laplacian-Gaussian filtering and binarization. As a physical measure, the radiographic index, which reflects the area of opacity in selected regions of interest (ROIs), was used. Fifteen men with MS and 15 men without MS were included in the study. ROIs were selected in the right upper and lower lung zones on radiographs, and the images were processed with the system. The radiographic indexes were determined in each ROI. As a measure of pulmonary blood flow redistribution, the upper-to-lower lung zone radiographic index ratio (U/L) was calculated. The U/L values correlated with pulmonary capillary wedge pressure values (r = .405, P = .025). The mean U/L value of the MS group was significantly higher than that of the non-MS group (1.16 +/- 0.14 vs 1.05 +/- 0.09, respectively; P = .016). These preliminary results indicate that this system can be used for quantitative estimation of the redistribution of pulmonary blood flow.

Initial data-element selection for the evaluation of picture archiving and communication system performance.

The completely new, hospital-wide picture archiving and communication system (PACS) now being implemented at Osaka University Hospital is described elsewhere in this issue. This paper lists the many studies of the department and hospital that were performed before the PACS for the purpose of identifying data elements for use in evaluating a PACS system. A second purpose of the initial data-element collection was to assist in the overall Osaka University PACS design. Selected studies from this work are presented here.

Transcatheter embolization of hepatocellular carcinoma: assessment of efficacy in cases of resection following embolization.

In 8 cases of hepatocellular carcinoma, hepatectomy was performed after hepatic artery embolization with Gelfoam. Complete necrosis of the tumor was found in 4 of these cases. Compared with the tumors that showed incomplete necrosis, the tumor in the complete necrosis group were small, thickly encapsulated, and located at sites remote from collateral circulation. Angiography and computed tomography after embolization accurately demonstrated tumor necrosis or continued viability, as confirmed by examination of resected specimens.