Noninvasive gadolinium-enhanced three dimensional computed tomography coronary angiography

Determination of infarct size in ex vivo swine hearts by multidetector computed tomography using gadolinium as contrast medium

OBJECTIVE

To demonstrate the feasibility of using multidetector computed tomography with gadolinium contrast (Gd-MDCT) for the quantification of myocardial infarct (MI).

MATERIALS AND METHODS

MI was induced in male swine (n = 6). One week later, the animals received 0.2-mmol/kg gadopentetate dimeglumine and were sacrificed. On the excised hearts, Gd-MDCT with several tube voltages (80, 120, and 140 kV), late gadolinium enhancement MRI (LGE-MRI), and triphenyl-tetrazolium-chloride staining were then conducted. We used a 2-SD threshold for the CT images and several threshold limits (2, 3, 4, 5, 6 SD, and full width at half-maximum [FWHM]) for the LGE-MRI images to delineate the infarct area. Total infarct volume and infarct fraction of each heart were calculated.

RESULTS

MI size measured by MDCT at 140 kV showed good correlation with the reference triphenyl-tetrazolium-chloride value. Applying an 80-kV tube voltage, however, significantly underestimated MI size. In our study, the LGE-MRI method, using the 6-SD threshold, provided the most accurate determination of MI size. LGE-MRI, using the 2- and 3-SD threshold limits, significantly overestimated infarct size.

CONCLUSIONS

The Gd-MDCT technique has been found suitable for the evaluation of MI in an ex vivo experimental setting. Gd-MDCT has the ability to detect MI even at low kV settings, but accuracy is limited by a high image noise because of reduced photon flux.

Feasibility of gadolinium-diethylene triamine pentaacetic acid enhanced multidetector computed tomography for the evaluation of coronary artery disease

BACKGROUND

Multidetector computed tomography (MDCT) has been proposed as a noninvasive method for the diagnosis of obstructive coronary artery disease (CAD). In patients with high risk of iodinated contrast adverse effects such as acute allergic-type reactions, the use of gadolinium could be an alternative.

OBJECTIVE

We sought to evaluate the feasibility of gadolinium-enhanced MDCT for the diagnosis of obstructive CAD.

METHODS

Twenty patients (mean age, 61 years; range, 50-73 years) referred for X-ray coronary angiography were studied by both gadolinium and iodine-enhanced 16-row MDCT coronary angiography. The degree of enhancement and the accuracy for detection of obstructive CAD (>50% diameter reduction) were evaluated with X-ray coronary angiography as the standard. Renal nephrotoxicity was strictly monitored.

RESULTS

Gadolinium- and iodine-enhanced MDCT showed adequate visualization of the coronary arteries in 310 of the 312 coronary artery segments that were available by X-ray angiography, respectively. The average density of the coronary arteries in both iodine and gadolinium CT scans was 253.65 Hounsfield unit (HU) and 135.20 HU, respectively. In a per-coronary segment analysis, gadolinium- and iodine-enhanced MDCT showed sensitivities of 89% vs 84%, specificities of 96% vs 95%, and negative predictive values of 97% vs 96%, respectively. In a per-patient analysis, both gadolinium- and iodine-enhanced MDCT showed sensitivities of 92.85% vs specificities of 83.33%. Intermethod agreement between gadolinium- and iodine-enhanced MDCT (kappa) was 0.95 (P < 0.0001).

CONCLUSION

Our preliminary results indicate lower attenuation with gadolinium but similar diagnostic accuracy for the detection of obstructive CAD when compared with iodine-enhanced MDCT. Therefore, gadolinium is a feasible alternative contrast agent for patients with iodine contrast allergy referred for MDCT coronary angiography.