High-resolution CT (HRCT) is the radiological imaging technique that most closely reflects changes in lung structure. It represents the radiological method of choice for the diagnostic work-up of patients with known or suspected diffuse interstitial lung disease. A single HRCT finding is frequently nonspecific, but the combination of the various HRCT findings together with their anatomic distribution can suggest the most probable diagnosis. The purpose of this article is to summarize the classic HRCT features of the most common diffuse interstitial lung diseases. Lists of differential diagnoses and distinguishing key features are provided to improve diagnostic confidence. The presence of classic HRCT features often obviates the need for biopsy. In patients with atypical findings, HRCT can be used to determine the most appropriate biopsy site.

New imaging techniques in the treatment guidelines for lung cancer. C. SchaeferProkop, M. Prokop. #ERS Journals Ltd 2002. ABSTRACT: Computed tomography (CT) remains the main imaging technique for the preoperative staging and post-therapeutic evaluation of bronchogenic carcinoma. Spiral CT has already overcome some of the problems encountered with central or more extensive tumours. Multislice CT offers further improvement and allows for scanning of the whole chest within a single breath-hold using a thin-section high-resolution technique. Problem-adapted sections in arbitrary directions become available and provide an excellent spatial resolution. One can expect improved accuracy for the evaluation of transfissural tumour growth, chest wall involvement, mediastinal infiltration and lymph node staging.Despite recent advances in magnetic resonance (MR) techniques for imaging the chest, the role of MR for staging of bronchogenic carcinoma remains limited. It offers advantages such as the assessment of chest-wall involvement or mediastinal involvement in patients in whom CT remains equivocal. Lymph-node-specific MR contrast agents offer new diagnostic potential for the assessment of metastatic disease.New techniques for the display of three-dimensional data sets include volume rendering and virtual bronchoscopy. These techniques represent new tools for the evaluation and demonstration of pathology within the central tracheobronchial tree. Their most important application is the guidance of bronchoscopic biopsies.The assessment of an indeterminate pulmonary nodule is frequently based on positron emission tomography imaging. As an alternative, nodule vascularization (contrast enhancement patterns on CT or magnetic resonance imaging (MRI)), calcifications (absorption characteristics at various X-ray energies on CT or dual energy radiography), and morphological features (high resolution imaging at CT) can be used as the basis for nodule differentiation. The dynamics of contrast enhancement in CT or MRI can also be used for the assessment of tumour viability after chemotherapy.Lung cancer screening programmes are still controversial. Low-dose computed tomography scanning and computed assisted detection algorithms based on chest radiographs or computed tomography scans form the technical basis for such projects.

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Computed tomographic angiography (CTA) is a minimally invasive technique for vascular imaging with the potential to become the primary imaging method for many angiographic applications in the abdomen. It is based on the rapid volume acquisition capabilities of spiral (or helical) CT and uses a properly timed intravenous contrast bolus to obtain a three-dimensional data set from the examined vascular region. This data set, consisting of overlapping transaxial CT images, can be interactively reviewed using arbitrary cut planes (multiplanar reformats), or it can be transformed into angiographic displays using maximum intensity projections (MIP) or three-dimensional shaded surface displays (SSD).Although there is an absolute limit to spatial resolution with CTA that precludes diagnostic assessment of abdominal vessels smaller than 1 mm, CTA has been shown to be an excellent tool for imaging the abdominal aorta and its large side branches [1][2][3][4][5]. Advantages over arterial angiography include use of the intravenous approach, direct information derived about vascular walls and perivascular structures, and the use of three-dimensional visualization techniques. With its fast acquisition time and relatively high spatial resolution, CTA compares favorably with MR angiography (MRA) and color-coded duplex ultrasonography. However, in contrast to these techniques, CTA images display only anatomic information and lack flow sensitivity.Although the basic idea of CTA is simple, there are numerous factors that influence image quality and may cause artifacts. Attention must be paid to scanning technique and contrast application in order to achieve diagnostic images of optimum quality. We describe our experience with more than 500 abdominal CT angiograms since 1991, discuss new developments in scan-

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