Computed tomography and magnetic resonance imaging: past, present and future

Abstract

The aims of this paper are to summarize the current recommendations for the use of computed tomography (CT) and magnetic resonance imaging (MRI) in the chest and to suggest some possible future developments.The main developments of CT in the chest have been the introduction of highresolution CT (HRCT), spiral CT and, more recently, multidetector spiral CT.HRCT is defined as thin-section CT (1-to 2-mm collimation scans), optimized by using a high-spatial resolution (edge-enhancing) algorithm. Several studies have shown that HRCT closely reflects macroscopic (gross) pathological findings. HRCT currently has the best sensitivity and specificity of any imaging method used for the assessment of focal and diffuse lung diseases.The advent of spiral CT and, more recently, multidetector CT scanners, has allowed for major improvements in the imaging of airways, pulmonary and systemic vessels, and lung nodules. Spiral CT facilitates multiplanar and three-dimensional display of structures and visualization of pulmonary and systemic vessels, with a level of detail that is comparable to that of conventional angiography. With the use of graphics-based software programs, spiral CT enables depiction of the luminal surface of the airways with images that resemble those of bronchoscopy (virtual bronchoscopy) or bronchography (virtual bronchography). Several studies have shown a high sensitivity and specificity for spiral CT in the diagnosis of acute pulmonary embolism. Therefore, spiral CT is rapidly becoming the imaging modality of choice in the diagnosis of pulmonary embolism.Like the radiograph, signal intensity on computed tomography is mainly due to a single parameter: electron density. The signal intensity of the magnetic resonance image depends on four parameters: nuclear density, two relaxation times called T1 and T2, and motion of the nuclei within the imaged lung volume. Abnormal soft tissue can be identified more easily through measurement of these four parameters than through use of computed tomography. Furthermore, because the spatial orientation of the image is determined by manipulation of magnetic fields, scans can be performed in any plane. The main indications for magnetic resonance in the chest have been in the evaluation of the heart, major vessels, mediastinum, and hilar structures because of the natural contrast provided by flowing blood. Of particular interest for the respirologist has been the recent development of magnetic resonance angiography. This technique consists of three-dimensional single breath-hold images obtained using gadolinium-based contrast agents. This is a promising technique for the diagnosis of acute and chronic pulmonary embolism. Eur Respir J 2002; 19: Suppl. 35, 3s- For many years, the plain chest radiograph was the only imaging modality used in the diagnosis of lung disease. With the advent of computed tomography (CT) came the first opportunity to assess gross lung structure. Conventional 8-to 10-mm collimation scans allowed better assessment of the lung parenchyma than was...

Evaluation of diagnostic accuracy of computed tomography to assess the angioarchitecture of pulmonary sequestration

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“…A distinct mass in the lower lobe, with or without cystic changes and bronchiectasis is mostly seen abnormalities on CT. It is reported that spiral CT demonstrates two thirds of the arterial supplies, and most venous drainages cannot be shown (8,9). Whereas, MDCT is capable to simultaneously demonstrate the arterial supply, venous drainage and parenchymal changes in a single examination (10,11).…”

“…Sonographic demonstration of a vascular supply is difficult; therefore the failure to depict the supply does not exclude the diagnosis. Several cases of MRI diagnosis of PS have been reported both in utero and infants (6)(7)(8). MRA is an other method for demonstrating the abnormal blood supply but because of motion artifacts optimal images can not always be obtained.…”

3D Vocal Tract Reconstruction Using Magnetic Resonance Imaging Data to Study Fricative Consonant Production

“…The technique uses a magnetic field and radiofrequency waves to create detailed images of the organs and tissues, and relies on the nuclear magnetic resonance of the hydrogen nucleus. Compared with images from other techniques, MRI provides excellent anatomical details [19] and is superior to computed tomography (CT) in distinguishing various tissue characteristics [13].…”

Imaging in lung disease

“…The present supplement covers several aspects of the role of imaging in the diagnosis of lung diseases, starting with an overview by MÜ LLER [4] of the development of magnetic resonance imaging and CT, how it developed, current possibilities and how it might develop in the future. The first part then deals with pulmonary embolism.…”