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Purpose <p>First-pass imaging using the bolus tracking (BT) method is recommended for computed tomography (CT) pulmonary angiography (CTPA) in pulmonary thromboembolism. However, pulmonary artery (PA) CT numbers remain low despite continuous contrast injection, potentially due to Valsalva maneuver and volume effects. Our institution has introduced a single-acquisition protocol for CTPA that prolongs contrast injection time and captures overlapping first-pass and inferior-vena-cava (IVC)-derived second-pass recirculation. This study aimed to compare PA attenuation and enhancement variability between the conventional BT method and the new combined technique.</p> Methods <p>Ninety-three patients who underwent CT for acute pulmonary thromboembolism were analyzed. Injection times were 30&#xa0;s for the BT method and 50&#xa0;s for the new method. In the BT method, scanning was initiated when attenuation in the ascending aorta reached 150 HU. In the new method, scanning was initiated 43&#xa0;s after the start of contrast injection. CT number of the PA was measured, with values &lt; 200 HU considered indicative of poor enhancement.</p> Results <p>PA attenuation variability was lower with the new method than with the BT method (coefficient of variation, 16.4% vs. 29.5%). Although mean attenuation was higher with the BT method (332.8 ± 98.7 HU vs. 288.2 ± 47.3 HU), four cases of poor enhancement were observed with the BT method, whereas no such cases occurred with the new method.</p> Conclusion <p>The single-acquisition combined first-pass and IVC-derived second-pass contrast enhancement technique reduced enhancement variability and provided more consistent PA enhancement than the conventional BT method, without additional radiation exposure or contrast dose.</p>

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Reduced variability of pulmonary artery enhancement using a single-acquisition combined first-pass and inferior-vena-cava-derived second-pass contrast technique in CT pulmonary angiography

  • 期刊论文

  • 发表日期：

    2026年7月28日

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  • Yuya Kawakami,
  • Ryosuke Irie,
  • Yoshiki Yamagishi,
  • Toshihiko Sugiura,
  • Takashi Matsumoto,
  • Takashi Iimori,
  • Takashi Uno

摘要

Purpose

First-pass imaging using the bolus tracking (BT) method is recommended for computed tomography (CT) pulmonary angiography (CTPA) in pulmonary thromboembolism. However, pulmonary artery (PA) CT numbers remain low despite continuous contrast injection, potentially due to Valsalva maneuver and volume effects. Our institution has introduced a single-acquisition protocol for CTPA that prolongs contrast injection time and captures overlapping first-pass and inferior-vena-cava (IVC)-derived second-pass recirculation. This study aimed to compare PA attenuation and enhancement variability between the conventional BT method and the new combined technique.

Methods

Ninety-three patients who underwent CT for acute pulmonary thromboembolism were analyzed. Injection times were 30 s for the BT method and 50 s for the new method. In the BT method, scanning was initiated when attenuation in the ascending aorta reached 150 HU. In the new method, scanning was initiated 43 s after the start of contrast injection. CT number of the PA was measured, with values < 200 HU considered indicative of poor enhancement.

Results

PA attenuation variability was lower with the new method than with the BT method (coefficient of variation, 16.4% vs. 29.5%). Although mean attenuation was higher with the BT method (332.8 ± 98.7 HU vs. 288.2 ± 47.3 HU), four cases of poor enhancement were observed with the BT method, whereas no such cases occurred with the new method.

Conclusion

The single-acquisition combined first-pass and IVC-derived second-pass contrast enhancement technique reduced enhancement variability and provided more consistent PA enhancement than the conventional BT method, without additional radiation exposure or contrast dose.