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High-resolution computed tomography (HRCT) is computed tomography (CT) with high resolution. It is used in the diagnosis of various health problems, though most commonly for lung disease. It involves the use of special computed tomography scanning techniques to assess the lung parenchyma. ==Technique== HRCT is performed using a conventional CT scanner. However, imaging parameters are chosen so as to maximize spatial resolution: (UCSF ILD Program Protocol for High-Resolution CT Scanning of the Chest ) *A narrow slice width is used (usually 1–2 mm) *A high spatial resolution image reconstruction algorithm is used *Field of view is minimized, so as to minimize the size of each pixel *Other scan factors (e.g. focal spot) may be optimized for resolution at the expense of scan speed Depending on the suspected diagnosis, the scan may be performed in both inspiration and expiration. The patient may also lie prone (face down) rather than the more usual supine (face up). As HRCT's aim is to assess a generalized lung disease, the test is conventionally performed by taking thin sections 10–40 mm apart. The result is a few images that should be representative of the lungs in general, but that cover only approximately one tenth of the lungs. Because HRCT does not image the whole lungs (by using widely spaced thin sections), it is unsuitable for the assessment of lung cancer or other localised lung diseases. Similarly, HRCT images have very high levels of noise (due to thin sections and high-resolution algorithm), which may make them non-diagnostic for the soft-tissues of the mediastinum. Intravenous contrast agents are not used for HRCT as the lung inherently has very high contrast (soft tissue against air), and the technique itself is unsuitable for assessment of the soft tissues and blood vessels, which are the major targets of contrast agents. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「High-resolution computed tomography」の詳細全文を読む スポンサード リンク
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