Time series of volumetric measurement of porcine three dimensional segmented myocardial perfusion by selective contrast injection using 256-slice cone beam computed tomography

Utility of 256-slice cone beam tomography for real four-dimensional volumetric analysis without electrocardiogram gated acquisition

PURPOSE

Current ECG-gated multislice CT can reveal any cardiac phase data, including four-dimensional (4D) images, but cannot acquire the whole heart in one scanning, and arrhythmias impair the quality of the images. We used a prototype 256-slice cone beam CT (Athena, Sony Toshiba), with which the whole heart can be acquired in one scanning.

MATERIALS AND METHODS

A pulsating device with contrast material (300 mgI/dl) diluted 10x with saline was moved at 5, 40, 60, 70, and 90 to-and-fro movements/min. Non-ECG-gated 256-slice cone beam CT with 256 x 0.5 mm slice thickness was performed during one to-and-fro motion at each rate. After acquisition, each to-and-fro motion was divided into 20 frames, and each volume was measured and volumetric curves were constructed.

RESULTS

Even without ECG-gated acquisition, the configuration of the pulsating device at any rate continued to the through plane without any gaps, and the 4D movie of the pulsating device could be observed at any rate except 60 movements/min. Volumes of end-diastole (ED) and end-systole (ES), and ejection fraction (EF) at static state were 81.7, 17.5 ml, and 79% respectively. ED volumes were 81.7, 81.7, 70.3, 63.7, 68.3 and 65.9 ml, ES volumes were 17.5, 30.9, 39.8, 62.7, 55.0 and 43.2 ml, and EF was 79, 62, 43, 2, 19 and 34% at 0, 5, 40, 60, 70, and 90 to-and-fro movements/min, respectively. The ratios of ED volume, using the static state as the reference, were 100, 86, 78, 84 and 81%, those of ES volume were 177, 227, 358, 314 and 247%, and those of EF were 78, 54, 3, 24 and 43% at 5, 40, 60, 70, and 90 to-and-fro movements/min, respectively. From the configuration of volumetric curves, only 5/min could be evaluated. At 60 movements/min, the same device images without any motion were observed in 4D images during one to-and-fro motion. This may be because one to-and-fro time and one scanning time were the same (1 s).

CONCLUSION

Even without ECG-gated acquisition, this new 256-slice cone beam CT achieved real 4D analysis of the pulsating device. The ED volume and the configuration of volumetric curve could only be evaluated up to 5 movements/min, but because of poor spatial resolution (1 s/rotation), even at 5 movements/min ES volume tended to be overestimated. As a result, EF tended to be underestimated, which may be improved in the next generation (0.5 s/rotation).

Superiority of synchrony of 256-slice cone beam computed tomography for acquiring pulsating objects. Comparison with conventional multislice computed tomography

PURPOSE

A prototype 256-slice cone beam computed tomography (CT) provides complete volumetric data within a single gantry rotation (1 s/rotation) with 0.5 mm slice-thickness.

MATERIALS AND METHODS

Calcified phantoms (200-400 HU) were attached to the balloon of a pulsating phantom and moved at a rate of 5-90/min. Acquisition was performed during one to-and-fro motion at each pulsation rate without electrocardiogram (ECG)-gating. Each period was divided into 10 phases, and compared to conventional multislice CT scanning without ECG-gating.

RESULTS

At 5-20/min, the configuration of calcified phantoms continued to the through-plane without gaps. At 60/min, duplicated calcified phantoms at end-systole and end-diastole were observed without motion. At 90/min, motion could be observed without gaps but was more blurred, and total calcified volume, Agatston scores, mean and max CT values of three phantoms were almost equal compared with those at static state. However, at 60/min, total calcified volume, scores, mean and max CT values of three phantoms were decreased to 64%, 37%, 80% and 56%, respectively, compared with those at static state. In multislice CT, even at lower rates, there were gaps in the through-plane. At 60/min, total calcified volume, scores, mean and max CT values of three phantoms were decreased to only 8%, 3%, 79% and 53%, respectively, compared with static state.

CONCLUSION

This new prototype's unique character (synchrony) enables the acquisition of pulsating objects. These can be acquired without gaps in the through-plane even in the absence of ECG-gating. However, its present temporal resolution only permits accurate quantitative evaluation of calcium up to 20/min.

Tricolored “Tricolore” myocardium by selective intracoronary injection of contrast using 256-slice cone-beam computed tomography

We report our experience with 256-slice cone-beam computed tomography following selective coronary arterial bolus injection in pigs, which distinguished the segmented left ventricular (LV) myocardium supplied by each coronary artery into three parts more clearly than with other modalities. Two pigs were anesthetized and catheters positioned in the left anterior descending branch (LAD) of the coronary artery in pig 1 and the left circumflex branch (LCx) in pig 2. 10 ml of iodinated contrast material diluted with 40 ml of saline was injected at a rate of 3 ml/s. Entire heart scanning was started simultaneously and continued for 25 s. We selected the most static images of the LV at around 5 s after contrast injection. Axial source and multiplanar reconstruction images from the right anterior oblique projection clearly revealed tricolored, segmented LV myocardial enhancement of the anterior and apical walls and inter-ventricular septum in pig 1, and the lateral and posterior walls in pig 2. We were able to identify the borders between the LV myocardium supplied by the LAD, the LCx and the right coronary artery, respectively, and this technique may facilitate new cardiovascular diagnoses.

Utility of triple channel injection of contrast material with mixture of saline, with acquisition in the cephalic direction for arterial trees in the thorax using multislice computed tomography

BACKGROUND

If contrast material is injected into the cubital vein, artifacts due to high concentration of the contrast material in the vein lead to deterioration of the opacification of the thoracic aorta and the major branches. We describe a new protocol employing a combination of triple channel contrast material injection and a mixture of saline with acquisition in the cephalic direction utilizing capability of 16-slice multislice CT.

MATERIALS AND METHODS

Of 35 subjects who underwent thoracic CT, 18 were injected with 70 ml contrast each prior to scanning with acquisition in the cephalic direction during the injection of 30 ml contrast diluted 50/50 with saline, followed by the injection of 20 ml of saline (new protocol). Seventeen subjects were injected each with 100 ml contrast at 3 ml/s, with scanning in the caudal direction (ordinary protocol).

RESULTS

In the new protocol, the major branches of the aorta and the left ventricle were more opacified, but the veins were less opacified compared with the ordinary protocol, resulting in clear delineation of the thoracic aorta and the major branches without artifacts.

CONCLUSIONS

A new acquisition protocol is described in which the thoracic aorta and the major branches can be evaluated without artifact due to high CT values in the veins. Faster, more informative CT scans can be performed using diluted contrast.