Diagnostic value of low-dose CT pulmonary angiography combined with iterative reconstruction in suspected pulmonary embolism

Objective

Assessing the utility of low-dose computed tomographic pulmonary angiography (CTPA) employing iterative reconstruction (IR) for the detection of pulmonary embolism (PE), we compared its image quality, and radiation exposure with standard-dose CTPA protocols.

Methods

Patients with suspected PE were prospectively and randomly allocated to either a low-dose CTPA with IR arm (study group, n = 80) or a standard-dose CTPA plus IR arm (control group, n = 80). The low-dose group used 70 kVp and automatic tube current modulation, while the standard-dose group used 120 kVp with conventional parameters. A 5-point scale was used to evaluate subjective image quality. Objective assessment of noise and contrast was performed by quantifying the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) within the pulmonary arteries. Radiation exposure was quantified via computed tomography dose index volume (CTDIvol) and dose-length product (DLP).

Results

Baseline characteristics were comparable between groups (P > 0.05). Subjective image quality was similar, with a non-significant trend towards lower scores in the low-dose group (median 4 [IQR 3–4]) compared to the standard-dose group (P > 0.05). Objective measures showed a non-significant 4.0 % and 5.5 % reduction in SNR and CNR, respectively, in the low-dose group (P > 0.05). Noise levels (SD) were comparable. The low-dose group demonstrated notable reduced radiation exposure: CTDIvol (P < 0.001), DLP (P < 0.001), and effective dose (P < 0.001).

Conclusion

Low-dose CTPA employing IR presents a viable option for PE diagnosis, providing similar diagnostic quality with significantly reduced radiation exposure.