High pitch, low voltage dual source CT pulmonary angiography: assessment of image quality and diagnostic acceptability with hybrid iterative reconstruction

Abstract

Increased use of CT Pulmonary angiography in suspected pulmonary embolism (PE) has driven research to minimize radiation dose while maintaining image quality and diagnostic accuracy. Following institutional review board approval, we performed a retrospective comparison study in patients with suspected PE. Patients were scanned using an ultra high pitch dual source technique (pitch=2.6) using 120 kV (SVCTPA) (n=54) or 100 kV (RV-CTPA) (n=52). SV-CTPA images were reconstructed using filtered back projection (SV-wFBP) and RV-CTPA images were reconstructed using both FBP (RV-wFBP) and Iterative Reconstruction (RV-IR). Comparison of radiation dose, diagnostic ability, subjective image noise, quality, and sharpness, diagnostic agreement, signal to noise (SNR) and contrast to noise ratios (CNR) were performed. Mean effective dose was 2.56± 0.19 mSv for the RV protocol compared to 5.36±0.60 mSv for the SV. The RV-CTPA protocol resulted in a mean DLP reduction of 52 % and mean CTDI reduction of 51 %. Pulmonary artery SNR and CNR were significantly higher on RV-IR images than SV-wFBP (p=0.007, p=0.003). Mean subjective image noise, quality and sharpness scores did not differ significantly between the SV-wFBP and RVIR images (p>0.05). Subjective quality scores were significantly better for the RV-IR group compared to the RV-wFBP group (p<0.001). Agreement between readers for presence or absence of pulmonary emboli on RV-IR images was almost perfect (κ=0.891, p<0.001). Iterative reconstruction complements ultra high pitch dual source CTPA examinations acquired using a reduced voltage resulting in higher mean pulmonary artery SNR and CNR when compared to both RVwFBP and SV-CTPA.

Establishment of CTPA Local Diagnostic Reference Levels with Noise Magnitude as a Quality Indicator in a Tertiary Care Hospital

“…Theoretically, scanning could be controlled by increasing or decreasing the pitch factor, where the CTDI vol received by patients would be reduced as the pitch factor increased, but at the expense of image quality [34,35]. However, for high-end MDCT scanners, such as second or third generation dual-source CT, a high temporal resolution ensures a reasonable diagnostic performance even with a high pitch factor [36][37][38]. Modern scanners were developed to cover a wider beam collimation range per rotation of the CT X-ray tube.…”

Values of thoracic contrast‑enhanced computed tomography in detecting incidental pulmonary thromboembolism in patients with malignant tumors

“…In addition, thoracic contrast-enhanced CT can also observe the disease-caused conditions in the lung parenchyma, mediastinal pleura, or chest wall (5). The changes in the lung parenchyma associated with PTE include pulmonary infarction, pulmonary hemorrhage, mosaic perfusion, masses, atelectasis, or pleural effusion (18,19). In this study, subarachnoid atelectasis occurred in 7 patients (11.67%), pulmonary metastases occurred in 8 patients (13.33%), pleural effusions were observed in 6 patients (10%), mosaic perfusion area was observed in 2 patients (3.33%), pneumonia occurred in 5 patients (8.33%), while for 32 patients (53.33%) no substantial findings were observed.…”

Acute pulmonary embolism multimodality imaging prior to endovascular therapy

“…A retrospective study of ultra-high-pitch dual-source CTPA in patients with suspected PE found that a reduced voltage (100 kV) compared to a standard voltage (120 kV) resulted in significantly reduced radiation dose, greater subjective image quality, and improved SNR and CNR. Diagnostic agreement between readers for the reduced voltage was very high (κ = 0.891) [83]. Iterative reconstructive algorithms can further reduce patients' radiation exposure [84].…”