Flash Spiral Mode Research Articles

Thoracic CTA in infants and young children: Image quality of dual-source CT (DSCT) with high-pitch spiral scan mode (turbo flash spiral mode) with or without general anesthesia with free-breathing technique.

To determine whether diagnostic quality thoracic computed tomography angiography (CTA) studies can be obtained without general anesthesia (GA) in infants and young children using dual-source computed tomography (DSCT) with turbo flash spiral mode (TFSM) and free-breathing technique. All consecutive infants and young children (≤ 6 years old) who underwent thoracic CTA studies from January 2018 to October 2020 for suspected congenital thoracic disorders were categorized into two groups: with GA (Group 1) and without GA (Group 2). All thoracic CTA studies were performed on a DSCT scanner using TFSM and free-breathing technique. Two pediatric thoracic radiologists independently evaluated motion artifact in three lung zones (upper, mid, and lower). Degree of motion artifact was graded 0-3 (0, none; 1, mild; 2, moderate; and 3, severe). Logistic models adjusted for age and gender were used to compare the degree of motion artifact between lung zones. Interobserver agreement between reviewers was evaluated with kappa statistics. There were a total of 73 pediatric patients (43 males (59%) and 30 females (41%); mean age, 1.4 years; range, 0-5.9 years). Among these 73 patients, 42 patients (58%) underwent thoracic CTA studies with GA (Group 1) and the remaining 31 patients (42%) underwent thoracic CTA studies without GA (Group 2). Overall, the degree of motion artifact was higher for Group 2 (without GA). However, only a very small minority (1/31, 3%) of Group 2 (without GA) thoracic CTA studies had severe motion artifact. There was no significant difference between the two groups with respect to the presence of severe motion artifact (odds ratio [OR] = 6, p = .222). When two groups were compared with respect to the presence of motion artifact for individual lung zones, motion artifact was significantly higher in the upper lung zone for Group 2 (without GA) (OR = 20, p = .043). Interobserver agreement for motion artifact was high, the average Kappa being 0.81 for Group 1 and 0.95 for Group 2. Although the degree of motion artifact was higher in the group without GA, only a small minority (3%) of thoracic CTA studies performed without GA had severe motion artifact, rendering the study nondiagnostic. Therefore, the results of this study support the use of thoracic CTA without GA using DSCT with TFSM and free-breathing in infants and young children. In addition, given that motion artifact was significantly higher in the upper lung zone without GA, increased stabilization in the upper chest and extremities should be considered.

Clinical application of flash spiral mode of high-pitch dual source CT in carotid, cardiac and cerebral vessels combined one-stop angiography.

This study aims to evaluate the clinical application value of flash spiral mode of high-pitch dual source CT in carotid, cardiac and cerebral vessels combined one-stop imaging. A total of 100 consecutive patients were given carotid, cardiac and cerebral vessels combined one-stop imaging at flash spiral mode of high-pitch dual source CT. 27 patients received DSA examination of carotid and cerebral vessels, and 38 patients received digital subtraction angiography (DSA) examination of the coronary artery at the same time. Carotid, cardiac and cerebral vessels combined one-stop imaging was compared with "golden standard", DSA image. The overall satisfaction rate of coronary arteries, extracranial segment of the carotid artery (CA-E), intracranial segment of the carotid artery (CA-I), and cerebral vessels (anterior, middle, and posterior cerebral artery) were 93%, 99%, 95% and 97% respectively, and the positive rate of hemadostenosis was consistent with DSA. The kappa value indicating consistency of cerebral, carotid and coronary artery vessels was 0.78382, 0.80654, 0.82398, respectively. The method of carotid, cardiac and cerebral vessels combined one-stop imaging by flash spiral mode of high-pitch dual source CT can provide high image quality. It comprehensively evaluates stenosis of carotid, cardiac and cerebral vessels, which is of great importance for early intervention in harmful events of the cardia and cerebrovascular disorder.

Single-phase Pulmonary Arteriovenous Separation CT Protocol with Estimated Time of Arrival Method Using 3rd Generation Dual Source CT: Its Success Rate of Pulmonary Arteriovenous Separation in Our Experience of 223 Cases

We retrospectively investigated the success rate of pulmonary arteriovenous separation in a single-phase computed tomography (CT) protocol using the estimated time of arrival (ETA) method. A total of 223 patients who underwent a single-phase CT protocol using the ETA method for pulmonary arteriovenous separation were included in the analysis. Dual source CT (SOMATOM Force, SIEMENS) was used for imaging. The tube voltage was 80 kVp, and the scan mode was turbo flash spiral mode. CT values of main pulmonary artery (MPA), peripheral pulmonary artery (pPA), peripheral pulmonary vein (pPV), left atrium (LA), ascending aorta (AAo) and descending aorta (DAo) were measured. When the difference in CT values on the central side was 100 Hounsfield unit (HU) or more, it was judged that the separation was successful. The mean CT values were 671.9±154 HU for MPA, 424.4±81.2 HU for LA, 551.1±142.6 HU for pPA, 351.6±94.0 HU for pPV, 362.2±75.8 HU for AAo, and 282.7±83.7 HU for DAo. The mean difference in CT values of the pulmonary artery and vein was 247.5±138.9 HU on the central side and 199.5±133.0 HU on the peripheral side. There were 90.1% of cases where the difference in CT values on the central side was 100 HU or more. In addition, a strong positive correlation (r=0.849, p<0.001) was found between the CT value of MPA and the CT value difference on the central side. The success rate of pulmonary arteriovenous separation by the ETA method, which is a method that enables stable pulmonary arteriovenous separation, was 90.1%.

Feasibility of low-dose coronary computed tomographic angiography used in atrial fibrillation patients

Objective: The diagnosis of coronary artery disease (CAD) in atrial fibrillation (AF) patients using coronary computed tomography angiography (CCTA) requires a large exposure dosage or repeated examinations. This study evaluates the feasibility of using low-dose CCTA in the double prospectively ECG-triggered high-pitch spiral acquisition mode (Double Flash Spiral mode).Methods: Twenty-eight AF patients with suspected CAD were recruited. Double Flash Spiral mode (tube voltage 100 kVp) and iterative reconstruction was used for CCTA examination. Two radiologists cross-evaluated the CCTA image quality. The effective radiation dose was measured for each patient.Results: Twenty-eight AF patients (10 female, 18 male, mean age 68.8 ± 13.9 y, body mass index 24.3 ± 2.3 kg/cm2) were recruited and 337 artery segments were evaluated. In total, 98.5% (332/337) of the coronary artery segments and 96.4% (27/28) of the AF patients were rated as diagnostically evaluable. Of these 27 diagnosable patients, 17 patients (63%) were diagnosed with multi-vessel stenosis. Besides, 5 of 28 patients (17.9%) have left atrial appendage thrombus. The quality of the integrated image was significantly better than either of the individual first or the second scans, based on segments (P < 0.001) and patients (P < 0.05). The mean effective radiation dose was 1.5 mSv ±0.4 mSv.Conclusions: Using the Double Flash Spiral mode at low radiation dose (mean 1.5 mSv), 98.5% of the coronary segments and 96.4% of the scans were of sufficient diagnostic quality.

Radiation dose and diagnostic accuracy of high-pitch dual-source coronary angiography in the evaluation of coronary artery stenoses.

"Flash Spiral" imaging is a new prospective ECG-triggered spiral scan mode that uses a very high-pitch for coronary computed tomography angiography (CTA). This enables complete image acquisition within one cardiac cycle with a very low radiation exposure. The aim of this study was to investigate the diagnostic accuracy, image quality, and effective radiation dose of prospectively ECG-triggered high-pitch spiral method (Flash spiral mode) of coronary CTA using dual-source technology for the evaluation of coronary artery stenoses. The study included 186 consecutive patients (115men, 71women; mean age: 53.37years) who underwent coronary CTA. Coronary CTA was performed with a 128×2-slice dual-source CT (Somatom Definition Flash, Siemens, Germany) using a prospectively ECG-triggered high-pitch spiral mode. Patients were divided into three groups according to heart rate (≤65bpm, 66-75bpm, ≥76bpm) and body mass index (BMI) (20-24kg/m(2), 25-29kg/m(2), 30-34kg/m(2)) values. The correlation between heart rates, image quality and BMI values are investigated. A four-point scale (1=excellent, 4=poor/non-diagnostic) was used to rank the comparative image quality. Effective radiation doses were calculated. Also the correlation between radiation dose, sex and BMI values were investigated. In addition, diagnostic accuracy of CTA for detection of significant (≥50%) coronary artery stenoses was compared with invasive coronary angiography findings of 612vessel segments in 38patients. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy rate were calculated. A total of 2976coronary artery segments were present. Of all coronary artery segments, 2381 (80%) had an image quality score of 1, and 1.5% segments were rated as "poor/non-diagnostic". When the correlation between heart rate and image quality is investigated, there was a significant difference between ≤65bpm and ≥76bpm groups. However, there was no significant difference between ≤65bpm and 66-75bpm groups. The mean effective dose was found as 1.3mSv (min: 0.5, max: 2.4mSv). The correlation between effective radiation dose and BMI was moderate. However, the correlation between gender and radiation dose was significant. Sensitivity, specificity, negative predictive value and accuracy of coronary CTA on a per-vessel segment were 90.1%, 97.4%, 98.6%, and 96.5%, respectively. Prospectively ECG-triggered high-pitch spiral mode coronary CTA provides high image quality and diagnostic accuracy, with very low radiation dose for evaluation and exclusion of coronary artery stenoses.

Dual Source CTを用いた冠状動脈造影CTにおける使用基準の有用性 心電同期高速二重螺旋スキャンと螺旋スキャン，非螺旋スキャンの被ばく線量比較

We believe that the patient exposure dose differs by heart rate for a coronary computed tomography angiography (CCTA), and we attempted to reduce patient exposure dose of the CCTA. Specifically, we made a clear difference of exposure dose between heart rate and optimal cardiac phase or some imaging methods. Next, we established criterion of the CCTA in our hospital, and usefulness was discussed. For examination methods, patients with a heart rate below 60 beats per minute (bpm) received a high-pitch spiral scan (Flash Spiral mode), those between 61 to 70 bpm received a step and shoot scan (SAS mode), and those of >70 bpm or an irregular heart rate received low-pitch spiral scan (Helical mode). The results of the clinical study showed that patient exposure dose reduced 87% in Flash Spiral mode (1.93±0.26 mSv) and 66% in SAS mode (4.88±1.24 mSv) compared with Helical mode (14.35±3.42 mSv). In our present study, we proved the usefulness of our criteria using CCTA. If the results of our present study become guidelines of CCTA users, we suggest that total patient exposure dose can be reduced.

THE IMAGE QUALITY AND DIAGNOSTIC ACCURACY OF HIGH-PITCH DUAL-SOURCE CORONARY ANGIOGRAPHY USING FLASH SPIRAL MODE IN PATIENTS WITH HIGH HEART RATES

ObjectivesTo investigate the image quality, diagnostic accuracy and radiation doses of prospectively ECG-triggered spiral acquisition mode (Flash Spiral mode) coronary CT angiography (CCTA) using high-pitch dual-source CT in patients with...

The image quality and influencing factors of high-pitch dual-source CT coronary angiography in patients with different heart rates

Objectives To investigate the image quality,influencing factors and radiation doses of prospectively ECG-triggered spiral acquisition mode (Flash spiral mode)coronary computed tomography angiography (CCTA) using high-pitch dual-source CT in patients with different heart rates.Methods One hundred and thirty-four consecutive patients with mean heart rate (HR) ＞ 65 beats per minute (bpm) and ≤ 100 bpm were included in this study as group A using Flash spiral mode setting at 20％ -30％ of the R-R interval and 134 consecutive patients with mean HR ≤65 bpm were enrolled as group B using Flash spiral scan mode at 55％ of the R-R interval; 134 consecutive patients with mean HR ＞ 65 and≤100 bpm using spiral scan mode were included as group C. The image quality scores, effective radiation dose and influencing factors of image quality in three groups were assessed. All statistical analyses were performed using SPSS.Results (1)The non-diagnostic coronary artery segments in group A (28/1842,1.52％) were more than in group B (8/1819,0.44％ ) ( x2 =10.97,P =0.001 ) and there was no significant difference between group A and group C (32/1838,1.74％) ( x2 =0.280,P =0.345).The number of patients with non-diagnostic coronary segments in group A( 10/134,7.5 ％ )was more than in group B (2/134,1.5 ％,x2 =5.52,P =0.018 ),while there was no significant difference between group A and group C (9/134,6.7％,x2 =0.057,P =0.812).(2)The average heart rate variability (HRV) of patients with different image scores in the three groups wcrc significantly different. In group A,the HRV of score 1,2 and 3 were (2.29 ± 1.06),(5.17 ± 1.37),(8.88 ± 1.53) bpm,respectively (F =170.402,P =0.001 ).In group B were (2.26±1.01),(5.97 ±1.82),(12.00 ±9.64) bpm,respectively (F=95.843,P=0.001).In group C were (2.61 ±1.85),(7.90 ±3.97),(11.22 ±5.62) bpm,respectively (F=68.629,P=0.001 ). (3) The average effective radiation doses in groups A and B were significant lower than in group C [ A group was 1.04 ± 0.16,B group was 1.03 ± 0.16 and C group was 7.05 ± 1.05,t =65.5 ( A vs C),P ＜0.01 ( A vs C) ].Conclusions Flash spiral mode of high-pitch dual-source provides high image quality with significant reduction of radiation exposure in patients with HR ≤ 65 bpm. Patients with heart rates ＞65 bpm and ≤100 bpm without cardiac arrhythmia can perform CCTA using Flash spiral mode with image acquisition time setting at 20％-30％ of the R-R interval. Key words: Coronary vessels; Heart rate; Cicatrix,hypertrophic; Cardiac-gated imaging techniques

High-pitch dual-source CT coronary angiography: analysis of the impact on image quality of altered electrocardiography waves during data acquisition

Electrocardiography (ECG) "altered waves" sometimes occur during data acquisition when computed tomography coronary angiography (CTCA) is performed with the prospectively ECG-triggered high-pitch (Flash spiral) mode using a second-generation dual-source CT. The aim of this study was to assess the effect of the ECG altered waves on image quality. Seventy-three consecutive patients with stable sinus rhythm ≤ 65 beats per minute were retrospectively enrolled in this study. CTCA was performed using the Flash spiral mode in which the data acquisition was prospectively triggered at 60 % of the R-R interval and completed within one cardiac cycle. The ECG waves before and during data acquisition were analyzed for grouping purposes. Image quality was evaluated using a four-point scale (1 = best, 4 = unevaluatable). Thirty patients (group 1) were found to have ECG altered waves during data acquisition, while 43 patients (group 2) had ECG "stable waves." The altered waves were seen as the baseline drifting; the broad, erected, or inverted P wave or QRS complexes; and a new wave. However, the length of the R-R interval did not change during the data acquisition. There were no significant differences in image quality scores between the two groups on the per-patient (2 ± 0.87 vs. 2.2 ± 0.74, P = 0.273) or per-segment (1.27 ± 0.54 vs. 1.32 ± 0.55, P = 0.577) basis. There were no significant differences in coronary evaluatability as well (per-patient; 93.3 vs. 95.3 %, P = 0.352; per-segment; 99.4 vs. 99.6 %, P = 1.0). CTCA image quality is not affected by ECG altered waves during data acquisition using the Flash spiral mode in low and stable heart rate patients. Thus, the ECG altered waves are considered artifacts.