CTA Advantages And Disadvantages

Advantages of CTA:
As effective as conventional angiography in the detection and characterisation of aneurysms, calcifications and rupture.
Superior to MRI as CT is faster, hence less motion artifacts and image degradation with CTA.
CTA has higher spatial resolution compared to MRI.
CTA can be performed in acutely ill patients on life support in contrast to MRI.
CTA generates 3D images within minutes on the workstation.
Rapid treatment planning (Saba, 2013. Stephen, 2011)

Disadvantages:
At times CTA may require larger volume of contrast than DSA.
CTA cannot delineate vessels as small as 3-5 mm and those close to the bones due to artefacts.
Cerebral veins may appear as clear as arteries hence making interpretation difficult for the radiologist.

MDCT can now produce x, y and z resolutions of 0.6 mm. A high-resolution three-dimensional image of the thorax can be achieved when x, y two dimensional slices are piled together. And this 3D image has all of the thoracic structures, including the airways, mediastinal blood vessels and mediastinal lymph nodes. The three-dimensional image thus obtained is a digital image, with a defined spatial dimension and grey-scale characteristics. This 3D image of the thorax can be studied, stored, acquired and shown as an informational structure bases on imaging. Using this principle the bronchial tree (and the surrounding structures if needed) can be identified, and removed from the larger image and studied in 3D digital space. Most of the companies now offer virtual bronchoscopy software with their scanners (Ferguson & McLennan,

• Follow-up of main bronchial stenosis at the site of anastomosis, post-lung transplantation, and balloon dilatation, the stenosis can be studied sequentially using virtual bronchoscopy instead of with a real bronchoscopic evaluation.
• Can give information about the relationship of any bronchial abnormality to surrounding structures, for instance the manubrium sternum in a high tracheal stenosis.
• Preplanning and calculation of bronchial stent or balloon size, length and diameter before the procedure is performed.
• The advanced uses of virtual bronchoscopy include, assisting a bronchoscopist in localizing and targeting a mediastinal or peripheral lung lesion for needle biopsy, and in the management of pulmonary emphysema with endobronchial valve-type procedures for targeting of the peripheral lung (Ferguson & McLennan, 2005, McAdams, 1998).

8.4 CT PERFUSION
CT perfusion is a technology that allows functional assessment of tissue vascularity and is particularly helpful in acute settings for stroke evaluation as CT is accessible readily and allows better image acquisition (Miles,