EVALUATION OF CONGENITAL LUNG ANOMALIES BY MDCT

Abstract

M ulti-detector CT (MDCT) is the latest advancement in the field of medical imaging. It has considerable advantage over single-detector helical CT in the form of shorter acquisition time, greater coverage, and superior image resolution. All these factors substantially increase the diagnostic accuracy of the examination by providing state-of-the-art image quality. Three dimensional (3D) isotropic volume imaging is possible with MDCT and, it provides an excellent anatomy of the chest. There by increasing the diagnostic yield comprehensively. With the advent of MDCT, there is paradigm shift in vascular imaging from conventional catheter angiography to MDCT angiography as this technique provides image quality that equals or surpasses that of conventional angiography. Recent advances in 3D volume rendering allows a fly through the tracheobronchial tree and the thoracic great vessels generating virtual endoscopic views in real-time. ADVANTAGES The main advantages of MDCT are shorter scan duration minimising the scan time, greater anatomic coverage in a single breath-hold allowing greater patient comfort and excellent 3D reconstructions. Faster imaging allows more consistent contrast enhancement with a single bolus ofcontrast, thus reducing the cost of examination. IMAGING TECHNIQUE The choice of MDCT parameters is of paramount importance in generating accurate visualisation of the thoracic anatomy. Analysis of the airways does not require intravascular contrast injection, because of the natural contrast between the airways and their environment. However, contrast media administration is routinely used to evaluate the mediastinal lesions as well as the vessels of the thorax.In the thorax with fast imaging time, the entire chest can be covered in a single breath-hold without any loss of resolution. With a capacity to cover a large area in a few seconds, the need for hyperventilation techniques is eliminated, and the volume of intravenous contrast material and the need for pediatric sedation are decreased. Although there are no firmly established rules for most of the contrast enhanced examinations of chest, a low kVp (~80 kVp) setting with properly increased mAs (~150 mAs) setting iscommonly used These exposure levels should be properly adjusted to individual requirements to decrease radiation exposure and to improve the contrast enhancement.