Conceptual design study of an intense x-ray source for coronary angiography

Background: CT coronary angiography is widely used to assess the presence of significant coronary artery disease (CAD). However, CT approach is associated with low but nonnegligible cancer risk. The purpose of this prospective multicenter study was to evaluate the diagnostic performance of coronary magnetic resonance angiography (MRA) in the ability to identify patients with significant CAD compared with coronary angiography. Materials and Methods: The subjects were recruited from 7 institutions. Free breathing coronary MR angiograms covering the entire coronary artery tree were obtained in 138 patients who were suspicious of CAD. Non-contrast enhanced images were acquired with a commercial 1.5T MR imager and five-element cardiac coils after sublingual administration of isosorbide dinitrate. Conventional X-ray coronary angiography was performed within 4 weeks after coronary MRA. MR and X-ray angiograms were sent to a core laboratory for blinded interpretation. Coronary MR angiograms were evaluated by two experienced investigators by using sliding partial MIP reconstruction. Quantitative X-ray coronary angiography analysis was performed with significant CAD defined as luminal narrowing of at least 50% of the diameter. Results: The mean imaging time of coronary MRA was 9.5 ± 4.9 minutes. The prevalence of significant disease on X-ray angiography was 45% (62/138). On a vessel-based analysis, the area under receiver operating characteristic (ROC) curve for the MRA compared with X-ray angiography was 0.90 (95% CI; 0.86 to 0.93). On a patient based analysis, the ROC area was 0.88 (95% CI; 0.81– 0.93). The sensitivity, specificity, positive and negative predictive values of coronary MRA by vessel analysis were 78% (95% CI; 68 – 86%), 86% (82–90%), 60% (51– 69%), 94% (90–96%). These values by patient analysis were 87% (95% CI; 76–94%), 71% (59 – 81%), 71% (59 – 81%), 87% (76–94%). Conclusions: In the current multicenter study using commercial 1.5T MR imagers and sliding partial MIP reconstruction, the diagnostic accuracy of coronary MRA compared to quantitative coronary angiography is good, reflected by an ROC area of 0.88 on patient-based analysis. High negative predictive value indicates that coronary MRA can be used for screening CAD.

Download Full-text

Abstract 2598: Radiation Exposure, Procedure Time And Contrast Load In Patients Referred For Coronary Angiography: Head-to-head Comparison Of Dual Source Ct With Conventional Coronary Angiography.

Circulation ◽

10.1161/circ.116.suppl_16.ii_575-b ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Carlos A Van Mieghem ◽

Annick C Weustink ◽

Marcel Kofflard ◽

A. Schreve-Steensma ◽

Niels A Matheijssen ◽

...

Keyword(s):

Coronary Angiography ◽

Radiation Exposure ◽

Contrast Material ◽

Conventional Coronary Angiography ◽

Dual Source Ct ◽

Procedure Time ◽

X Ray ◽

Iodinated Contrast ◽

Dual Source ◽

The Mean

Introduction and aim: Dual Source CT (DSCT) scanners, with an increased temporal resolution (83 ms), are becoming widely available. To evaluate the current potential of this scanner in the clinical arena, we performed a head-to-head comparison with conventional coronary angiography (CCA) taking into account the following parameters: radiation exposure, procedure time and contrast load. Methods: During a one-year period (april 2006 to march 2007) we compared a consecutive patient group who underwent DSCT (318 patients, 222 male, mean age 68±11 years) and CCA (352 patients, 258 male, mean age 61±12) respectively. Patients with previous bypass surgery were excluded. In DSCT, the volume of iodinated contrast material was adapted to the scan time. A contrast bolus was injected in an antecubital vein at a flow rate of 5.0 ml/s followed by a saline chaser of 40 ml at 5.0 ml/s. Each tube provided 412 mAs/rot (maximum), and full X-ray tube current was given during 25–70% of the RR-interval. Exposure data were collected using the x-ray dosimetrical reports from DSCT and CCA. Results: The mean procedure time using DSCT and CCA was 16.1±4.7 min and 44.1±25.5 min (p<0.001), respectively. The mean contrast load in DSCT and CCA was 77.9±7.6 ml and 175.3±4.3ml (p<0.001), respectively. The overall radiation exposure for DSCT and CCA was calculated as 15.3±4.0 mSv and 5.7±4.3 mSv, respectively. Radiation exposure with DSCT was significantly lower (p<0.001) in patients with a heart rate of >70 bpm (12.9±3.1 mSv ) as compared with patients with heart rates <70 bpm (16.4±3.8 mSv). Conclusion: In today’s practice currently available DSCT scanners perform favorably as compared with CCA, considering procedure time and patient contrast load. Radiation exposure with DSCT remains higher but should not be considered a major disadvantage taking into account the relatively old age group that generally undergoes coronary angiography and the major benefit of not being exposed to the risks of an invasive procedure.

Download Full-text