Computed Tomography Angiography (also called CT angiography ) is a technique used to produce detailed images of both blood vessels and tissues in various parts of the body. An iodine-rich contrast material (dye) is usually injected through a small cannula placed in a vein of the arm before CT scan while the contrast flows through the blood vessels to the various organs of the body. An automatic injection pump connected to the IV gives contrast material at a controlled rate. After scanning, the images are processed using a special computer and software and reviewed in different planes and projections.
CT angiography is used to examine blood vessels and the organs supplied by them in various body parts, including:
- Abdomen (such as the kidneys and liver)
- Legs and feet
- Arms and hands
CTA is commonly used for the following purposes:
Head and Brain Angiography
High quality head and body angiography to examine brain and carotid arteries using a unique magic glass technology through which the system is capable of showing VR(3D) and MIP (Multiplaner reconstruction) image projections, simultaneously on a single image view. Magic glass view is extremely useful to show minute lesions, vascular enhancements.
To examine the pulmonary arteries in the lungs to rule out pulmonary embolism, a serious but treatable condition. This is called a CTPA.
To visualize blood flow in the renal arteries (those supplying the kidneys) in patients with high blood pressure and those suspected of having kidney disorders. Narrowing (stenosis) of a renal artery is a cause of high blood pressure (hypertension) in some patients and can be corrected. A special computerized method of viewing the images makes renal CT angiography a very accurate examination. Also done in prospective kidney donors.
Non-invasive heart screening through Cardiac CT -Coronary Angiography
Cardiac CT is a non-invasive procedure of using CT scan to determine if you have blocked coronary arteries that may cause a heart attack. This is done through a quick test called coronary artery evaluation.Cardiac CT can also determine other types of heart problems such as congenital anomalies; valve functioning; myocardial infarctions etc.
The computed tomography scan (CT scan) is similar to an xray, but produces clearer and more detailed images of the heart. During a CT scan, the x-ray beam moves in a circle around the body. This allows for many different views of the heart and its structure, and provides much greater detail.
How does it work
During the test, X-rays are passed through the body to produce high-resolution, 3-dimensional pictures of the moving heart and great vessels. Analysis of these images reveals if either fatty or calcium deposits (plaques) have built up in the coronary arteries. The test also reveals other structural details of the heart.
Benefits of Cardiac CT
CT Angio (CTA) reveals the number of obstructions and the extent of these obstructions in the blood vessels without any invasion. This helps in planning and preparation for the treatment. For example, if stenting is required, you will have beforehand knowledge of the type and number of stents required.CTA helps in better planning of treatment both in terms of time and money. It can save any last minute surprises when compared to direct admission to a Cath lab. CT Coronary Angiography has emerged as the most reliable non-invasive modality for evaluation of heart diseases.
• Takes only a few seconds to evaluate heart condition
• Non-invasive and painless
• No hospital admission required, it is an out patient procedure
• It is a safe and convenient procedure. Cardiac CT imaging process for the patient is almost similar to any other contrast CT scanning
Use of Cardiac CT
For Preventive Cardiac Screening:
CT angiography is highly useful for patients who are asymptomatic but at high risk of having coronary artery disease.
Patients presented with atypical chest pain or breathlessness, patients giving history of chronic smoking, chronic hypertension, strong family history of premature heart disease and those with unclear electrocardiographic changes or stress-test results.
It is also a screening tool for patients on Cholesterol reducing medications and for patients on exercise and nutrition therapies. The CT coronary angiogram screening will help them to estimate the progress / regress of the disease.
For Post-Operative Screening and Evaluation: CT angiography is also recommended for patients with history of open heart surgery and had by pass grafting (Coronary Artery Bypass Grafting).It is a convenient way to follow up and evaluate graft functioning and detect any blockages to the by pass grafts inserted into the coronary arteries. Patients who had undergone CABG, CT Angiography can clearly demonstrate grafts blockages if any, the extent of graft functioning, the points of grafts insertions (Ostiums & anastomotic junctions) in three dimensional views.
For Post-Stenting Screening and Evaluation: With recent advancements in stent technology, insertion of stents into coronary arteries is becoming a preferable methods than the open heart surgeries in many patients, even with triple vessel disease cases. Follow up study to check patency /functioning of stents can also be conveniently performed through CT angiography for many patients.3D images with Stent 3D image with stenosis.
CT at Dr. Dodas Diagnostics and Healthcare - what so special ?
Lowest X-Ray exposure.
Our CT is the most advanced CT scanner in the world. Moreover it is also equipped with dose optimization and dose reduction technology for controlling X-Ray radiation to patients. Step and Shoot cardiac CT ensures that the patient is exposed to lowest possible X-rays while the best quality of image is generated.
Unique adaptive multi cycle reconstruction algorithm achieves temporal resolutions as fast as 53 milliseconds which leads to excellent quality images demonstrating even tiny plaques and calcifications.
Cardiac Imaging for High BMI patients
Doing cardiac screening of heavy patients (high BMI) has always been a challenge. But with the latest technology of CT at Doda Diagnostics and Healthcare, excellent images can be produced for even heavy patients.
Cardiac Imaging for patients with Arrhythmia
If irregular beats occur, they can adversely affect the image quality of the scan .With Philips new Auto arrhythmia editing tool, irregular beats can be automatically detected, edited and the raw data reconstructed again to generate images without any artifacts. Auto arrhythmia editing is used to automatically detect irregular ECG events during a cardiac CT.
Cardiac CT in addition to Coronary Angiography is done for Calcium scoring to measure the extent of calcification in the coronary arteries also. Excess of calcium in the coronary arteries carries a risk for cardiac event. A high calcium score, predisposes to severe stenosis. A calcium score of 0 does not rule out a soft plaque, but definitely rules out significant coronary artery disease. Rupture of a soft plaque is the commonest cause of an acute coronary syndrome.A calcium score of more than 400 is considered severe and it necessitates prevention of advancement of atherosclerosis and plaque formation.
Calcium scoring is done as a separate stand-alone test, though is routinely performed as an initial part of the entire cardiac CT examination.
Indications of CT Coronary Angiography.
1. Asymptomatic patient with family history of coronary artery disease
2. Patient with high risk factors
3. Prior to non-coronary surgery in the adult population
a. Pre – ASD repair
b. Pre – Valvular repair
c. Pre – Tumor surgery
4. Follow up post CABG
5. Atypical chest pain with doubtful coronary origin
6. Evaluation of coronary anomalies
7. Exclusion of coronary stenosis in symptomatic high risk patient
8. Assessment of cardiac neoplasm
9. Assessment of stent patency
10. Detection and characterization of congenital heart disease
11. Diagnosis of pericardial disease
12. Prior to major (non-cardiac) surgery
13. Non-conclusive stress tests
Precautions to be taken before a non-invasive angiography:
Kidney Function Tests should be done prior to the angiography. Patients Blood Urea Nitrogen and Serum Creatinine reports should be ready before the test.
The patient should be fasting for 4 hours prior to the test.