Multi-slice computed tomography (MSCT) is a non-invasive modality to visualize coronary arteries with an overall good image quality. Improved spatial and temporal resolution of 64-slice and dual-source computed tomography (DSCT) scanners are supposed to have a positive impact on diagnostic accuracy and image quality. However, quantitative parameters to compare image quality of 16-slice, 64-slice MSCT and DSCT are missing.
A total of 256 CT examinations were evaluated (Siemens, Sensation 16: n = 90; Siemens Sensation 64: n = 91; Siemens Definition: n = 75). Mean Hounsfield units (HU) were measured in the cavum of the left ventricle (LV), the ascending aorta (Ao), the left ventricular myocardium (My) and the proximal part of the left main (LM), the left anterior descending artery (LAD), the right coronary artery (RCA) and the circumflex artery (CX). Moreover, the ratio of intraluminal attenuation (HU) to myocardial attenuation was assessed for all coronary arteries. Clinical data [body mass index (BMI), gender, heart rate] were accessible for all patients.
Mean attenuation (CA) of the coronary arteries was significantly higher for DSCT in comparison to 64- and 16-slice MSCT within the RCA [347 +/- 13 vs. 254 +/- 14 (64-MSCT) vs. 233 +/- 11 (16-MSCT) HU], LM (362 +/- 11/275 +/- 12/262 +/- 9), LAD (332 +/- 17/248 +/- 19/219 +/- 14) and LCX (310 +/- 12/210 +/- 13/221 +/- 10, all p < 0.05), whereas there was no significant difference between DSCT and 64-MSCT for the LV, the Ao and My. Heart rate had a significant impact on CA ratio in 16-slice and 64-slice CT only (p < 0.05). BMI had no impact on the CA ratio in DSCT only (p < 0.001). Improved spatial and temporal resolution of dual-source CT is associated with better opacification of the coronary arteries and a better contrast with the myocardium, which is independent of heart rate. In comparison to MSCT, opacification of the coronary arteries at DSCT is not affected by BMI. The main advantage of DSCT lies with the heart rate independency, which might have a positive impact on the diagnostic accuracy.
Authors: Burgstahler C, Reimann A, Brodoefel H, Daferner U, Herberts T, Tsiflikas I, Thomas C, Drosch T, Schroeder S, Heuschmid M.
Full text: Eur Radiol. 2009 Mar;19(3):584-90. Epub 2008 Oct 25
64-Slice CT technology revolutionizes heart attack prevention
Cardiac CT Angiography (CTA) is a new and revolutionary way to non-invasively visualize the inside of the coronary arteries. With the latest advances in high resolution scanning, the Siemens Sensation 64-Slice CT Scanner can create amazingly detailed and accurate images of the heart, lungs, and arteries in just seconds. That means easier, painless diagnosis of the cause of symptoms and earlier detection of developing problems before symptoms have started.
CT Angiography vs Cardiac Catheterization:
Until now, Cardiac Catheterization has been the most important tool for evaluating the arteries of the heart. But, Cardiac Catheterization is an invasive procedure that requires an incision in the groin, inserting a catheter into an artery in the leg and advancing the catheter under X-ray guidance to the heart. Contrast dye is then injected directly into the arteries on the surface of the heart and X-rays are taken that show whether any of the vessels are narrowed.
Cardiac CT Angiography requires only a small IV in vein of the arm. A small amount of dye is injected into the vein followed by a 10 second CT scan of the heart.
With Cardiac CT Angiography there is no risk of vascular damage, heart attack or stroke.
After the scan, the IV is removed and you can go home, to work, or resume your normal activities immediately.
Avoiding Invasive Tests with Cardiac CT Angiography:
Cardiac CT Angiography can accurately exclude the presence of significant blockage in the coronary arteries. Nearly 1 out of every 3 people advised to have a Cardiac Catheterization ultimately find they do not have any have significantly blocked arteries. Cardiac CT Angiography can be an excellent way to avoid the risk of complications and eliminate the need for a stay in the hospital.
Cardiac CT Angiography is a highly accurate alternative to Cardiac Catheterization for those people who have an abnormal stress test but are unlikely to have significant heart disease. In people with non-diagnostic (equivocal or borderline) stress tests, or those with “negative” stress tests but who are at high risk of coronary artery disease, Cardiac CT Angiography can quickly and non-invasively determine whether significant coronary artery disease is present. If you have an elevated Coronary Calcium Score, a Cardiac CT Angiography can be used to determine the severity of narrowing of the arteries.
Insurance Coverage:
Cardiac CT Angiography is covered by Medicare and by many private health plans.
Cardiac CT Angiography and radiation:
A typical Cardiac CT Angiography will expose patients to about 8-12 mSv of radiaiton. A Nuclear Stress Test is typically 12-25 mSv of radiation exposure. The annual natural exposure to radiation from the environment is about 3.5 mSv. While it is important to minimize unnecessary radiation exposure as much as possible, the radiation exposure from a Cardiac CT Angiography is not different from other commonly used medical tests.
