Computed tomographic pulmonary angiography using low tube voltage and slow contrast medium injection.

Abstract

Purpose: The diagnosis of acute pulmonary thromboembolism (PTE) is often performed by computed tomographic pulmonary angiography (CTPA). This study investigated the effects of a CTPA protocol combining slow contrast medium injection and low tube voltage on radiation exposure and image quality.

Methods: We retrospectively analyzed 82 patients undergoing CT scans for cancer treatment efficacy or follow-up, and simultaneous PTE exclusion. Patients were divided into two groups. Those in Group A (n = 43) received slow contrast injection (0.7-1.5 mL/s), and those in Group B (n = 39) received rapid injection (2.6-4.2 mL/s). All CT scans were performed using a multi-detector row CT scanner with optimized tube voltage and current settings. Contrast medium doses were adjusted based on the patient's body weight.

Results: Group A had significantly lower radiation exposure compared with Group B. PTE was diagnosed in eight patients in Group A and seven in Group B, with no significant difference in prevalence rates. While Group B indicated higher mean CT values in the CTPA phase, the difference in the mean CT value of the pulmonary artery was only 29.6 Hounsfield units. Group A demonstrated superior contrast enhancement in parenchymal organs during the second phase.

Conclusion: The slow-injection CTPA method proved effective for simultaneous PTE exclusion and cancer treatment evaluation, maintaining diagnostic accuracy with reduced risks associated with rapid injection.