Image Quality and Radiation Dose of Lower Extremity CT Angiography Using 70 kVp, High Pitch Acquisition and Sinogram-Affirmed Iterative Reconstruction

Abstract

ObjectivesThe purpose of this study was to assess image quality and radiation dose of lower extremity CT angiography (CTA) with 70 kVp, high pitch acquisition and sinogram-affirmed iterative reconstruction (SAFIRE).MethodsLower extremity CTAs were performed on 44 patients: 22 patients were examined using protocol A (120 kVp, pitch of 0.85 and 120 ml of contrast agent on a first-generation dual-source CT) (120 kVp group) and 22 patients were evaluated with protocol B (70 kVp, pitch of 2.2 and 80 ml of contrast agent on a second-generation dual-source CT) (70 kVp group). Images from the 120 kVp group were reconstructed with filtered back projection (FBP) and images from the 70 kVp group with SAFIRE. The attenuation, image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Two radiologists subjectively assessed image quality of lower extremity arteries, plantar arterial enhancement and venous contamination of all patients. Radiation dose was compared between the two groups.ResultsHigher mean intravascular attenuation was obtained in the 70 kVp group (70 vs. 120 kVp group, 555.4±83.4 HU vs. 300.9±81.4 HU, P<0.001), as well as image noise (20.0±2.8 HU vs. 17.5±3.2 HU, P = 0.010), SNR (32.0±7.0 vs. 19.1±6.9, P<0.001) and CNR (28.1±6.6 vs 15.9±6.3, P<0.001). No difference in subjective image quality and plantar arterial enhancement was found between 120 kVp group and 70 kVp group (all P>0.05). The venous contamination score was 1.5±0.8 for 120 kVp group while no venous contamination was found in 70 kVp group. The inter-observer agreement was moderate to good for both groups (0.515∼1, P<0.001). The effective dose was lower in 70 kVp group (0.3±0.1 mSv) than in 120 kVp group (1.6±0.7 mSv)(P<0.001).ConclusionsLower extremity CTA using 70 kVp, high pitch acquisition and SAFIRE, except increasing imaging noise, allows for lower radiation dose and contrast material volume without compromising image quality.

70-kVp High-pitch Computed Tomography Pulmonary Angiography with 40 mL Contrast Agent

“…It has been demonstrated that lowering tube voltage from 100 kVp to 80 kVp could reduce the radiation dose of CTPA by approximately 30% (28). Recently, 70-kVp acquisition has been applied to coronary, pulmonary, cerebral, and lower extremity CTA (17,(29)(30)(31)(32), showing its promising potential for substantial radiation dose reduction. In one recent study by Wichmann et al, single-source 70-kVp CTPA with SAFIRE and dual-source 70-kVp CTPA with a standard 1.2 pitch resulted in doses of 0.94 ± 0.17 mSv and 2.35 ± 0.58 mSv, respectively (17).…”

Non–Electrocardiogram-Triggered 70-kVp High-Pitch Computed Tomography Angiography of the Whole Aorta With Iterative Reconstruction

“…6,[16][17][18][19][20][21][22] High-pitch acquisition allows for imaging of the whole aorta in less than 2 seconds, 12 thus avoiding long exposure time and reducing radiation dose and required administered volume of contrast agent. The CTA with lower tube voltages at 100 kVp and 6,24,25 which demonstrated that such techniques maintain diagnostic image quality while allowing for lower radiation dose and contrast agent volume.…”

“…Recent studies emphasized the potential of 70-kVp CTA for assessment of peripheral artery, coronary artery diseases and cerebral artery. [16][17][18][19][20][21][22][23] Qi et al 18 demonstrated that 70-kVp acquisition during lower extremity high-pitch CTA with IR allows for a significant reduction of radiation dose and contrast material volume without compromising image quality despite a slight increase in image noise. Zhang et al 19 found that prospectively ECG-triggered high-pitch coronary CTA at 70 kVp with 30 mL of contrast agent is able to provide diagnostic image quality at a radiation dose of less than 0.2 mSv in patients with a body mass index below 25 kg/m 2 and a heart rate of less than 70 beats per minute.…”

“…Recently, several authors investigated 70-kVp CTA for imaging of peripheral artery, coronary artery disease, and cerebral artery in adults and reported significant dose savings with a diagnostic image quality in selected patients. [16][17][18][19][20][21][22][23] However, to our knowledge, the potential of 70-kVp CTA for CTA of the aorta has not been investigated so far. Additionally, reduced tube voltage may allow for a significant reduction of contrast medium volume in CTA studies because the attenuation of iodinated contrast media increases at low tube voltage.…”

Low-Voltage, High-Pitch Computerized Tomography Angiography of the Infrarenal Aorta and Lower Extremity Vessels

“…For example, selection of a lower x-ray tube voltage setting can lead to a substantial decrease in radiation dose. The tube voltages of 80 5 and 70 kVp 6,7 have been verified to be feasible for lower extremity CTA with substantial reduction of radiation dose. Automatic tube current modulation (ATCM) techniques have also been reported to be effective in radiation dose reduction.…”