Multidetector row computed tomography (MDCT) has modified the imaging approach for the asses- sment of many diseases. The technique enables the acquisition of a volume of data, rather than slices.
The most recent clinical developments involving this technique include the screening of colorectal polyps, the detection of lung nodules, the scree- ning for cardiac and coronary artery diseases, and the easy three-dimensional rendering of various vessels in any part of the body.
Advantages of the technique include the rapid acquisition and three-dimensional rendering of images even of the pulsating heart or vessels. The spatial resolution is improving and so is the dia- gnostic confidence. Due to the faster acquisition time, we are moving towards automated procedu- res of acquisition and image reading.
However, there are several challenges that ra- diology departments face in the use of this rapidly evolving technique. These challenges include (among others).
• Management of the workload of a CT suite; to- day it takes more time to position patients than to acquire the images. The organization of the day-to-day work must be optimized.
• The number of images to be read by the radio- logist has dramatically increased. The time ne- cessary for their interpretation is also increa- sing. In the very near future, automatic three- dimensional rendering of the raw data will simplify this.
• The rapid translation of the table may increase the number of motion artifacts. Various me- thods have already been developed to reduce motion artifacts.
• The rate of injection and volume of contrast needed for the examinations have to be adap- ted. High-concentration contrast media are now preferable.
Of utmost importance is the control of the ra-
diation delivered during a MDCT examination, both in children and in adults. The manufacturers are progressively introducing methods that will al- low the radiation dose to be reduced. For instance, attenuation-based online modulation of the tube current in order to reduce the milliampere settings has now become commercially available and this permits a dose reduction without loss of image quality.
Important questions that need to be answered soon concern the evaluation of the clinical impact of systematic screenings that all radiologists tend to perform (i.e., for pulmonary nodules). Are we doing better? Are we improving the medical care and outcome?
Finally, other techniques are also able to provi- de the same or similar clinical information; com- parisons are necessary in order to choose the best technique and to reduce cost and optimize patient management.
Suggested Reading
Fleischmann D (2003) Use of high-concentration con- trast media in multiple-detector-row CT: principles and rationale. Eur Radiol 13 [Suppl 5]:M14-M20 Akbar SA, Mortele KJ, Baeyens K et al (2004) Multidetec-
tor CT urography: techniques, clinical applications, and pitfalls. Semin Ultrasound CT MR 25:41-54 Kelly DM, Hasegawa I, Borders R et al (2004) High-re-
solution CT using MDCT: comparison of degree of motion artifact between volumetric and axial me- thods. AJR Am J Roentgenol 182:757-759
Roos JE, Desbiolles LM, Weishaupt D et al (2004) Multi- detector row CT: effect of iodine dose reduction on hepatic and vascular enhancement. Rofo Fortschr Geb Rontgenstr Neuen Bildgeb Verfahr 176:556-563 Schoellnast H, Tillich M, Deutschmann HA et al (2004) Improvement of parenchymal and vascular enhan- cement using saline flush and power injection for multiple-detector-row abdominal CT. Eur Radiol 14:659-664
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Introduction
E. Freddy Avni
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4 MDCT: Scanning and Contrast Protocols
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Herzog C, Britten M, Balzer JO et al (2004) Multidetec- tor-row cardiac CT: diagnostic value of calcium sco- ring and CT coronary angiography in patients with symptomatic, but atypical, chest pain. Eur Radiol 14:169-177
Achenbach S, Moselewski F, Ropers D et al (2004) De- tection of calcified and noncalcified coronary athe- rosclerotic plaque by contrast-enhanced, submilli- meter multidetector spiral computed tomography:
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Fleischmann D (2003) MDCT of renal and mesenteric
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Nasir K, Budoff MJ, Post WS et al (2003) Electron beam CT versus helical CT scans for assessing coronary calcification: current utility and future directions.
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