Split-bolus Protocol Research Articles

Biphasic split-bolus injection protocol for routine contrast-enhanced chest CT: comparison with conventional early-phase single bolus technique.

To present a routine contrast-enhanced chest CT protocol with a split-bolus injection technique achieving combined early- and delayed phase images with a single aquisition, and to compare this technique with a conventional early-phase single-bolus chest CT protocol we formerly used at our institution, in terms of attenuation of great thoracic vessels, pleura, included hepatic and portal venous enhancement, contrast-related artifacts, and image quality. A total of 202 patients, who underwent routine contrast-enhanced chest CT examination aquired with either conventional early-phase single-bolus technique (group A,n = 102) or biphasic split-bolus protocol (group B,n = 100), were retrospectively included. Attenuation measurements were made by two radiologists independently on mediastinal window settings using a circular ROI at the following sites: main pulmonary artery (PA) at its bifurcation level, thoracal aorta (TA) at the level of MPA bifurcation,portal vein (PV) at porta hepatis, left and right hepatic lobe, and if present, thickened pleura (>2 mm) at the level with the most intense enhancement. Respective normalized enhancement values were also calculated. Contrast-related artifacts were graded and qualitative evaluation of mediastinal lymph nodes was performed by both reviewers independently. Background noise was measured and contrast-to-noise ratios (CNRs) of the liver and TA were calculated. While enhancement of thoracic vessels and normalised MPA enhancement did not differ significantly between both groups (p > 0.05), enhancement and normalised enhancement of pleura, liver parenchyma and PV was significantly greater in group B (p < 0.001). Perivenous artifacts limiting evaluation were less frequent in group B than in A and mediastinal lymph nodes were judged to be evaluated worse in group A than in group B with an excellent agreement between both observers. No significant difference was detected in CNRTA (p = 0.633), whereas CNR liver was higher in group B (p < 0.001). Our split-bolus chest CT injection protocol enables simultaneous enhancement for both vascular structures and soft tissues, and thus, might raise diagnostic confidence without the need of multiple acquisitions. We think that this CT protocol might also be a promising alternative in lung cancer staging, where combined contrast-enhanced CT of the chest and abdomen is indicated. We therefore suggest to further evaluate its diagnostic utility in this setting, in particular in comparison with a late delayed chest-upper abdominal CT imaging protocol.

The improvement of cardiac multispiral computed tomography protocol for planning interventional arrhythmia management

Purpose. The study aimed at the comparison of computed tomography (СT) contrast enhancement (CE) protocols for optimal visualization of cardiac chambers, evaluation of their impact on results of non-invasive superficial cardiac mapping.Methods. The study included 93 patients with heart rhythm disorders in whom catheter ablation of arrhythmia was planned. Noninvasive cardiac mapping for arrhythmia localization was performed and included multichannel ECG-registration and CT with intravenous СE (1st group - monophasic (50 patients), 2nd group - split-bolus (18 patients), 3rd group - with pre-bolus (25 patients). Qualitative and quantitative (measurement of mean blood attenuation in four chambers, calculation of ventricular-myocardial [VM] contrast-to-noise ratio VM-LV и VM-RV for the left ventricle [LV] and right ventricle [RV], respectively) parameters were compared between the groups. Fusion of ECG and CT data was carried out a semi-automatic mode with a non-invasive imaging complex.Results. Regardless of CE technique, sufficient and homogeneous contrast attenuation was obtained for the left atrium (LA) and LV (mean blood attenuation in LA more than 278 HU, LV 250 HU, VM-LV 0,582). In most cases, the enhancement of the right heart was insufficient with the monophasic protocol; the average CT density was lower than 200 HU, VM-RV 0,256. The split-bolus protocol improved visualization of the right atrium (RA) and RV (blood density in RA 258HU, RV 227HU, VMRV 0,541); however, there was a heterogeneity of the RA cavity due to artifacts from the superior vena cava (VC) and unenhanced blood from the inferior VC. Pre-bolus administration increased the contrast ratio between RA myocardium and blood due to the improvement of blood CT density in the inferior VC (blood density 294 HU). The quality of RV CE was similar to 2nd group (blood density 264 HU, VM-RV 0,565).Conclusion. The split-bolus and with pre-bolus CE protocols improve visualization of the RV, supporting the high-level enhancement of the left heart. The protocol with a pre-bolus is preferable for exact differentiation of the right atrial endocardial contour.

MODERN ASPECTS OF THE DIAGNOSIS OF SEVERE COMBINED TRAUMA USING COMPUTED TOMOGRAPHY

Relevance . The variety of options for combining injuries and disorders occurring in the body with a combined injury, the need for rapid decision-making on treatment require rapid diagnosis of the entire volume of injuries and determining the severity of the injury, but there is still no single protocol for examining such victims. The aim of the work was to present a modern CT study protocol for patients with concomitant trauma. Materials and methods . The results of computed tomography of 30 patients with severe concomitant trauma were analyzed. All the victims were admitted in the first hours after the injury. Men were 30 (67 %), women – 10 (33 %), the average age was 41.3 ± 7.6 (22–79) years. Traditional multiphase full-body MSCT was performed in 20 patients, in 10 patients a special protocol was used for the study of the "whole body" by the method of divided bolus. The results of the study . Craniocerebral injuries were detected in 15 (50 %), spinal injuries – in 7 (23.3 %). Simultaneous injuries to the chest and abdomen were detected in 19 (63.3 %) of the victims. When subjectively evaluated, the quality of the images obtained using the full-body MSCT protocol with bolus separation and the standard multiphase protocol for the diagnosis of traumatic injuries was equivalent. The average radiation load per patient with traditional multiphase full-body MSCT is 66 % higher than with the split-bolus protocol. Conclusions. Full-body MSCT using a split bolus is a modern technique that fully meets the diagnostic conditions for severe combined trauma and, with a decrease in the radiation dose, allows you to determine all possible injuries in the victim in a single study.

Split vs. Single Bolus CT Urography: Comparison of Scan Time, Image Quality and Radiation Dose

The purpose of this study was to compare the scan time, image quality and radiation dose of CT urograms (CTU) using a split vs. single bolus contrast media injection technique. A total of 241 consecutive CTUs performed between August 2019-February 2020 were retrospectively reviewed. There were three study groups: Group 1, <50 years old, 50/80 cc split-bolus administered at 0 and 700 s post initiation of injection, with combined nephrographic and excretory phases; group 2, ≥50 years old, same split-bolus protocol; and group 3, ≥50 years old, 130 cc single bolus injection, with nephrographic and excretory phases acquired at 100 s and 460 s post injection initiation. The recorded data elements were scan time, number of excretory phases, imaging quality based on opacification of the urinary collecting system (<50%, 50–75%, 75–100%), and dose-length product (DLP). Associations between group and categorical variables were assessed (Chi-square); mean scan time and DLP were compared (one-way ANOVA). Following analysis, proportionally fewer CTUs required a repeat excretory phase in group 3 (32/112, 28.6%) than in groups 1 (25/48, 52.1%) and 2 (37/80, 46.3%) (p = 0.006). Mean scan time was significantly lower in group 3 (678 s) than in groups 1 (1046 s) and 2 (978 s) (p < 0.0001). There was no association between groups and image quality (p = 0.13). DLP was higher in group 3 (1422 ± 837 mGy·cm) than in groups 1 (1041 ± 531 mGy·cm) and 2 (1137 ± 646 mGy·cm) (p = 0.003). In conclusion, single bolus CTU resulted in significantly fewer repeat phases and faster scan time at the expense of a slightly higher radiation dose.

The improvement of cardiac multispiral computed tomography protocol for planning interventional arrhythmia management

Purpose. Comparison of computer tomography (СT) contrast enhancement (CE) protocols for optimal visualization of cardiac chamber, definition it’s influence on results of non-invasive superficial cardiac mapping.Materials and methods. The study included 93 patients with heart rhythm disorders who planned catheter ablation of arrhythmia. Noninvasive cardiac mapping was made for topical diagnostics. It includes multichannel ECG-registration and CT with intravenous СE (1st group monophasic (50 patients), 2nd group split-bolus (18 patients), 3rd group with pre-bolus (25 patients). Qualitative and quantitative (measurement of mean blood attenuation in four chambers, calculation of ventricular-myocardial contrast-to-noise ratio VM-LV и VM-RV for left ventricle (LV) and right ventricle (RV), respectively) parameters were compared between groups. Fusion of ECG and CT data was made semi-automatic with diagnostic complex «Amycard 01К».Results. Regardless of CE technique was noted sufficient and homogeneous contrast attenuation of left atrium (LA) and LV (mean blood attenuation in LA more than 278 HU, LV 250 HU, VM-LV 0,582). Enhancement of right heart was insufficient with monophasic protocol, in most cases the average CT density was lower than 200 HU, VM-RV 0,256. Split-bolus protocol improves visualization of right atrium (RA) and RV (blood density in RA 258HU, RV 227HU, VM-RV 0,541), however there was heterogeneity of RA cavity because of artifacts from superior vena cava (VC) and unenhanced blood from inferior inferior VC. Using of pre-bolus increases contrast ratio between RA myocardium and blood due to increasing CT density of blood in inferior VC (blood density 294 HU). Quality of right ventricle CE was similar to 2nd group (blood density 264 HU, VM-RV 0,565).Conclusion. CE protocols split-bolus and with pre-bolus improve visualization of right ventricle, supporting the high level enhancement of left heart. Protocol with pre-bolus is preferable for exact differentiation of right atrial endocardial contour.

Split-bolus injection protocol with optimized timings of contrast medium injection and CT scanning for 3D CT angio-venography before laparoscopic gastrectomy.

To propose an optimization method of contrast medium injection for the split-bolus protocol based on the contrast medium pharmacokinetics and investigate the utility of the optimized split-bolus protocol in 3D CT angio-venography for laparoscopic gastrectomy. A pharmacokinetic relationship between injection duration and time to the peak enhancement was taken into account in the protocol design. The first 20 consecutive patients underwent a multi-phase scan with a single-bolus injection (single-bolus protocol), and the next 20 underwent the proposed split-bolus protocol. CT attenuations of the arteries and veins and dose-length products (DLPs) were compared between the two protocols. Two radiologists visually assessed arterial and venous depictions and the misregistrations. Mean arterial CT attenuations were not significantly different between the two protocols. Though mean venous CT attenuations for the split-bolus protocol were 7-11% lower than those of the single-bolus protocol, they were visually evaluated as similar. The mean DLP of the split-bolus protocol was 46% lower than that of the single-bolus protocol. Misregistration between the arteries and veins occurred 35-80% during the single-bolus protocol, but was not indicated in the split-bolus protocol. The split-bolus protocol with optimized timing was more effective for providing improved image quality with reduced radiation dose compared with the single-bolus protocol in 3D CT angio-venography for laparoscopic gastrectomy.

Split-bolus single-pass CT for vascular complications in acute pancreatitis: assessment of radiation dose and multi-phasic contrast enhancement compared to single-bolus multi-pass CT

To assess vascular contrast enhancement and radiation dose of split-bolus single-pass computed tomography (CT) compared to single-bolus multi-pass CT for acquiring a multi-phasic study. Patients who underwent CT for acute pancreatitis were included retrospectively. Thirty consecutive patients scanned with a split-bolus protocol were compared to 30 consecutive patients scanned with a single-bolus protocol. Data were collected on attenuation measurements (aorta, portal vein and spleen) and images were assessed for subjective vascular enhancement quality and splenic homogeneity. Radiation dose was measured by dose-length product (DLP). There was no significant difference in the aortic (p=0.88) or portal vein (p=0.35) attenuation values between the two groups. The percentage of examinations reaching the target aortic and portal attenuation in the split-bolus group were 96.7% and 93.3%, and in the single-bolus group were 96.7% and 85.7%, respectively. The mean DLP was 492 mGy.cm for the single-bolus group and 940 mGy.cm for the split-bolus group (p < 0.0001). Subjective assessment revealed higher rates of splenic heterogeneity in the split-bolus group. In acute pancreatitis, split-bolus imaging can produce arterial and venous enhancement comparable to a multi-pass technique with a significant reduction in radiation dose. Loss of temporal resolution and increased splenic heterogeneity are the main disadvantages. The low prevalence of pseudoaneurysms favours the lower-dose imaging technique.

Additive value of split-bolus single-phase CT scan protocol for preoperative assessment of lung cancer patients referred for video-assisted thoracic surgery.

We aimed to assess the additive value of the split-bolus single-phase computed tomography (CT) scan protocol to preoperatively assess patients with lung cancer, who were referred for video-assisted thoracic surgery, when compared to a standard staging CT protocol. We included 160 patients with lung cancer who underwent a split-bolus single-phase CT scan protocol (split-bolus protocol), which can acquire whole-body staging CT and pulmonary artery-vein separation CT angiography (PA-PV CTA) in a single acquisition and 160 patients who underwent whole-body staging CT (standard protocol). We compared the quality of the staging CT images of hepatic parenchyma, portal vein, and hepatic vein between both protocols. We also investigated image quality on PA-PV CTA images in the split-bolus protocol and recorded the number of patients that underwent the 3D PA-PV CTA imaging process. The split-bolus protocol for staging CT images demonstrated a slightly higher enhancement with regard to the hepatic parenchyma (p = 0.007) and hepatic vein (p = 0.006) than the standard protocol. There was no significant difference in the quality of the staging CT images between both protocols (p = 0.067). The mean CT number for the main pulmonary artery and the left atrium for the PA-PV CTA images in the split-bolus protocol were 289.1HU and 172.8HU, respectively. Among the images associated with the split-bolus protocol, 98.1% were of appropriate quality for 3D PA-PV CTA imaging. The split-bolus protocol is a dose-efficient protocol to acquire the staging CT and PA-PV CTA images in a single session and provides sufficient image quality for preoperative assessment in patients with lung cancer.

The Harms of Hematuria Evaluation: Modeling the Risk-Benefit of Using Split Bolus Computerized Tomography Urography to Reduce Radiation Exposure in a Theoretical Cohort.

Computerized tomography urography is used to evaluate patients with gross or microscopic hematuria. Computerized tomography urography is a high radiation dose scan and, thus, it confers a higher risk of secondary malignancy. A computerized tomography urography split bolus protocol reduces radiation exposure but it may reduce sensitivity. In this study we used a theoretical cohort of patients with hematuria in which to model the risk of missing malignancies against the benefit of averting secondary malignancies. We calculated the prevalence of renal cell carcinoma and upper tract urothelial carcinoma in patients with hematuria by pooled analysis of cohort studies, which in conjunction with split bolus sensitivity allows for the estimation of missed malignancies. The number of prevented secondary malignancies was calculated from lifetime attributable risk estimates. Sensitivity analyses were run to determine the minimum sensitivity required for a net population benefit. Estimates of split bolus computerized tomography urography sensitivity ranged from 80% to 100% (mean 95.2%). At the low estimate of 80% sensitivity split bolus computerized tomography urography was beneficial in men and women with microscopic hematuria at ages less than 50 and less than 60 years, respectively. An increase in sensitivity to 90% improved the benefit 1 decade in each gender, representing 68.8% of patients with microscopic hematuria. The overall population of patients with microscopic hematuria benefited from split bolus computerized tomography urography at 91.1% sensitivity. However, in patients with gross hematuria the threshold for an overall population benefit was high at 98.4% sensitivity. Exposure to ionizing radiation risks causing secondary malignancy. These data indicate that split bolus computerized tomography urography may be performed safely in 70% of the population of patients with microscopic hematuria. However, it is not currently advisable in patients with gross hematuria or in other patients at high risk.

Split-bolus vs. multiphasic contrast bolus protocol in patients with pancreatic cancer or cholangiocarcinoma

PurposeTo investigate the image quality, diagnostic accuracy, and dose reduction potential of a split-bolus protocol(SBP) compared with a multiphasic protocol(MPP) in the detection of recurrent or progressive pancreatic ductal adenocarcinoma(PDAC) or cholangiocarcinoma(CC) using contrast- enhanced computed tomography(CECT). Materials and MethodsThis prospective study included 56 patients who underwent CECT, 28 with our institutional standard MPP(100 ml contrast bolus) and 28 with a novel SBP(110 ml). Radiation exposure was determined in terms of total dose- length product(DLP) and computed tomography dose index(CTDI). Image quality was measured objectively by analysis of attenuation in Hounsfield units(HU) in regions of interest(ROIs) and subjectively by two blinded readers using a Likert scale. Diagnostic accuracy and interreader variability were tested. ResultsThe total DLP of the SBP group(498.1 ± 43.7 mGy*cm) was significantly lower than in the MPP group(1,092.5 ± 106.9 mGy*cm; p < 0.001). The SBP showed higher contrast enhancement of all critical anatomical structures including portal vein, liver, and pancreas compared with the MPP, except for the aorta(SBP: 326.9 ± 15.7 HU vs. MPP: 246.7 ± 12.2 HU; p < 0.001).Subjective analysis revealed poorer image quality ratings for important landmarks with the MPP (resection surface: p = 0.624, portal vein: p = 0.395, liver p = 0.361). The two blinded readers correlated significantly. Sensitivity, specificity, positive and negative predictive values (PPV/NPV), and overall interreader variabilities correlated significantly. Furthermore, significantly fewer slices per exam were required for the SBP(1,823 vs. 3,235; p < 0.001). ConclusionThe SBP provides the same image quality and diagnostic accuracy as an MPP while significantly lowering radiation exposure in CT follow-up of PDAC or CC.

A review of split-bolus single-pass CT in the assessment of trauma patients.

The purpose of this study was to review and compare the image quality and radiation dose of split-bolus single-pass computed tomography(CT) in the assessment of trauma patients in comparison to standard multi-phase CT techniques. An online electronic database was searched using the MESH terms "split-bolus," "dual phase," and "single pass." Inclusion criteria required the research article to compare a split contrast bolus protocol in a single-pass scan in the assessment of trauma patients. Studies using split-bolus CT technique in non-traumatic injury assessment were excluded. Six articles met the inclusion criteria. Parenchymal and vascular image qualities, as well as subjective image quality assessments, were equal or superior in comparison to non-split-bolus multi-phase trauma CT protocols. Split-bolus single-pass CT decreased radiation exposure in all studies. Further research is required to determine the superior split-bolus protocol and the specificity and sensitivity of detecting blunt cerebrovascular injury screening, splenic parenchymal vascular lesions, and characterization of pelvic vascular extravasation.

Split-bolus pancreas CTA protocol for local staging of pancreatic cancer and detection and characterization of liver lesions.

To validate the use of a split-bolus pancreas CTA protocol for local staging of pancreatic cancer and to evaluate its ability to detect and characterize liver lesions. Consecutive patients with pancreatic cancer who underwent split-bolus pancreas CTA between 12/2015 and 12/2016 were included in this IRB-approved HIPAA-compliant retrospective study. Objective evaluation of the abdominal vessels, the pancreas, the liver, and lesions, if present, was performed with attenuation measurements and tumor conspicuity and contrast-to-noise ratio (CNR) calculations. An abdominal radiologist with 20years of experience performed subjective evaluation of image quality and blindly detected and characterized liver lesions. Any inconclusive findings or grading scores were evaluated in consensus with another abdominal radiologist with 7years of experience. Liver findings were validated using a composite reference standard to assess accuracy. There were 82 pancreatic cancer patients with a total of 91 liver findings. Tumor conspicuity and CNR were 60.8±35.1 HU and 8.0±5.8 for the pancreatic lesions and 58±34.7 HU and 9.7±6.3 for the liver lesions, respectively. The accuracy, sensitivity, and specificity of the split-bolus protocol for the hepatic findings were correspondingly 89/91 (97.8%, 95% CI 92.3-99.4), 58/60 (96.7%, 95% CI 88.6-99.1), and 33/33 (100%, 95% CI 89.6-100). The subjective image quality ratings were optimal in more than 89% of the cases for various structures, with no non-diagnostic ratings. Split-bolus pancreas CTA protocol allows for detection and staging of pancreatic cancer, both for the primary tumor and detection and characterization of liver lesions.

Split-bolus single scan CTA for evaluation of mesenteric ischemia.

To evaluate split-bolus single scan CTA protocol for evaluation of acute mesenteric ischemia. In this HIPAA-compliant IRB-approved study, consecutive patients evaluated for mesenteric ischemia between 11/2015 and 10/2016 were included. Patients scanned prior to 4/2016 were scanned with multiphasic CTA protocol and after with split-bolus single scan CTA. Objective and subjective evaluation was performed by three board-certified readers. Findings were correlated to composite clinical reference outcome. Eighty patients were included: 40 with split-bolus and 40 with multiphasic CTA protocol with similar age (60.3±16.2years vs. 64.7±17.0years, p=0.19) and BMI (28.0±6.7 vs. 27.0±8.7, p=0.56). SMA attenuation was higher in multiphasic protocol compared to split-bolus protocol (336.5±97.5HU vs. 258.0±67.3HU, p<0.001) with similar SMV attenuation (multiphasic 213.7±58.4HU vs. split-bolus 194.2±52.2HU, p=0.14). Optimal phase of bowel, liver, and spleen enhancement was seen in similar high proportion (94-99%) in both protocols. There were 8/40 (20%) positive cases of mesenteric ischemia in each group. There was no difference in the diagnostic confidence of the readers for evaluation of the mesenteric vessels and bowel ischemia. There were no missed cases of mesenteric ischemia in either group. Mean effective dose was 42% lower in the split-bolus group, p<0.001. There was a higher number of axial images to review in multiphasic protocol compared to split-bolus protocol (437.9±48.7 vs. 263.5±31.2, p<0.001). The split-bolus protocol for evaluation of mesenteric ischemia is clinically feasible with confident and accurate diagnostic ability, while reducing number of images and decreasing radiation exposure to the patient.

Application value of split-bolus spectral computed tomography in the portal venography

Objective To investigate the effect of split-bolus spectral computed tomography(CT) on the portal venography and radiation dose. Methods The prospective study was adopted. The clinical data of 119 patients who underwent spectral CT at China-Japan Union Hopital from September 2014 to March 2015 were collected. Patients were randomly divided into the portal venography with split-bolus spectral CT single-phase enhanced scan group and portal vein multi-phase scan group by random sequence method. In the portal venography with split-bolus spectral CT single-phase enhanced scan group, the spectral CT was used with the method of split-bolus single phase imaging, and in the portal vein multi-phase scan group, standard spiral CT was used to perform three-phase scan. Two observers evaluated CT portal venography subjectively and objectively, measured CT values, contrast to noise ratio (CNR), signal noise ratio (SNR), and calculated radiation dose. Observed indices included (1) choice of optimal monochromatic images. (2) CT values of portal veins, measurement of CNR and SNR. (3) Subjective scoring of portal venography quality. (4) Comparison of radiation dose. Measurement data with normal distribution were presented as±s, comparison between groups was analyzed by independent sample t test. Comparison of count data was analyzed by chi-square test. Results The 113 patients were screened for eligibility, including 59 in the portal venography with split-bolus spectral CT single-phase enhanced scan group and 54 in the portal vein multi-phase scan group. (1) Choice of optimal monochromatic images: optimal monochromatic images were abstracted at 60 keV from spectral CT portal venography. (2) CT values of portal veins and measurement of CNR and SNR: the CT values of intrahepatic portal vein, extrahepatic portal vein and branches of portal vein were (319±44)HU, (328±53)HU, (294±45)HU in the reconstructed images at the energy level of 60 keV in the portal venography with split-bolus spectral CT single-phase enhanced scan group and (213±41)HU, (228±49)HU, (210±41)HU in the portal vein multi-phase scan group, with significant differences between the 2 groups(t=8.04, 6.34, 6.82, P 0.05). The SNR of intrahepatic portal vein, extrahepatic portal vein and branches of portal vein were 31±6, 29±6, 27±6 in the portal venography with split-bolus spectral CT single-phase enhanced scan group and 29±7, 28±9, 26±6 in the portal vein multi-phase scan group, respectively, with no significant differences (t=-0.688, 0.615, 0.600, P>0.05). (3) Subjective scoring of portal venography quality: the subjective score of image quality of portal venography was 14.3±1.0 in the portal venography with split-bolus spectral CT single-phase enhanced scan group and 12.5±1.8 in the portal vein multi-phase scan group, with a significant difference (t=12.43, P<0.05). (4) Comparison of radiation dose: the radiation dose was (8.1±1.1)mSv of patients in the portal venography with split-bolus spectral CT single-phase enhanced scan group and (17.4±7.5)mSv in the portal vein multi-phase scan group, with a significant difference (t=24.14, P<0.05). Conclusion Spectral CT portal vein imaging combined with split-bolus protocol can achieve better manifestations of portal vein and its branches, and reduce radiation dose in the scanning process. Key words: Liver diseases; Portal vein; Spilt-bolus; Tomography, X-ray computed; Spectral imaging; Radiation dose

Endoleak detection using single-acquisition split-bolus dual-energy computer tomography (DECT)

ObjectivesTo assess a single-phase, dual-energy computed tomography (DECT) with a split-bolus technique and reconstruction of virtual non-enhanced images for the detection of endoleaks after endovascular aneurysm repair (EVAR).MethodsFifty patients referred for routine follow-up post-EVAR CT and a history of at least one post-EVAR follow-up CT examination using our standard biphasic (arterial and venous phase) routine protocol (which was used as the reference standard) were included in this prospective trial. An in-patient comparison and an analysis of the split-bolus protocol and the previously used double-phase protocol were performed with regard to differences in diagnostic accuracy, radiation dose, and image quality.ResultsThe analysis showed a significant reduction of radiation dose of up to 42 %, using the single-acquisition split-bolus protocol, while maintaining a comparable diagnostic accuracy (primary endoleak detection rate of 96 %). Image quality between the two protocols was comparable and only slightly inferior for the split-bolus scan (2.5 vs. 2.4).ConclusionsUsing the single-acquisition, split-bolus approach allows for a significant dose reduction while maintaining high image quality, resulting in effective endoleak identification.Key Points• A single-acquisition, split-bolus approach allows for a significant dose reduction.• Endoleak development is the most common complication after endovascular aortic repair (EVAR).• CT angiography is the imaging modality of choice for aortic aneurysm evaluation.

Split-Bolus Single-Pass Multidetector-Row CT Protocol for Diagnosis of Acute Pulmonary Embolism.

Background:Currently computed tomography pulmonary angiography (CTPA) has become a widely accepted clinical tool in the diagnosis of acute pulmonary embolism (PE).Objectives:To report split-bolus single-pass 64-multidetector-row CT (MDCT) protocol for diagnosis of PE.Patients and Methods:MDCT split-bolus results in 40 patients suspicious of PE were analyzed in terms of image quality of target pulmonary vessels (TPVs) and occurrence and severity of flow-related artifact, flow-related artifact, false filling defect of the pulmonary veins and beam hardening streak artifacts. Dose radiation to patients was calculated.Results:MDCT split-bolus protocol allowed diagnostic images of high quality in all cases. Diagnosis of PE was obtained in 22 of 40 patients. Mean attenuation for target vessels was higher than 250 HU all cases: 361 ± 98 HU in pulmonary artery trunk (PAT); 339 ± 93 HU in right pulmonary artery (RPA); 334 ± 100 HU in left pulmonary artery (LPA). Adequate enhancement was obtained in the right atrium (RA):292 ± 83 HU; right pulmonary vein (RPV): 302 ± 91 HU, and left pulmonary vein (LPV): 291 ± 83 HU. The flow related artifacts and the beam hardening streak artifacts have been detected respectively in 4 and 25 patients. No false filling defect of the pulmonary veins was revealed.Conclusion:MDCT split-bolus technique by simultaneous opacification of pulmonary arteries and veins represents an accurate technique for diagnosis of acute PE, removes the false filling defects of the pulmonary veins, and reduces flow related artifacts.

Split-Bolus Portal Venous Phase Dual-Energy CT Urography: Protocol Design, Image Quality, and Dose Reduction.

The purpose of this study is to evaluate the image quality of split-bolus portal venous phase urography and the potential reduction of radiation dose by using a second-generation dual-source dual-energy CT (DECT) scanner. DECT urography was performed in 84 patients. Unenhanced CT was performed 20 minutes after drinking 800 mL of water. The split-bolus protocol consisted of a sequence of injections, as follows: 200 mL of normal saline (2.0 mL/s), 50 mL of contrast medium (2.5 mL/s) at 0 second, 70 mL of contrast medium (2.5 mL/s) at 360 seconds, and a saline flush of 25 mL. The scan was started at 420 seconds. Virtual unenhanced images were reconstructed from contrast-enhanced images. The mean CT density and signal-to-noise ratio (SNR) of the renal parenchyma, vessels, upper urinary tract, normal reference tissues, and tumors were measured for image quantitative analysis. Image quality and opacification of the collecting systems were rated by two radiologists using 3- or 4-point scales. The SNR of all measured sites, except the renal pelvis, showed a statistically significant correlation (p < 0.001) between the true unenhanced and virtual unenhanced images. The overall sensitivity of stone detection was 87.5% (28/32) in virtual unenhanced images. Image quality of the renal parenchyma, arteries, and veins was excellent in 59.5%, 75.0%, and 97.6% of cases, respectively. Opacification of the intrarenal collecting systems, proximal, middle, and distal ureters, and bladder was complete in 92.9%, 83.9%, 78.6%, 77.4%, and 26.2% of patients, respectively. Omitting the unenhanced scan can reduce the mean radiation dose from 15.6 to 6.7 mSv. Portal venous phase split-bolus DECT urography provides sufficient image quality with potential to reduce radiation exposure.

Implementation of a split-bolus single-pass CT protocol at a UK major trauma centre to reduce excess radiation dose in trauma pan-CT

To quantify the dose reduction and ensure that the use of a split-bolus protocol provided sufficient vascular enhancement. Between 1 January 2014 and 31 May 2014, both split bolus and traditional two-phase scans were performed on a single CT scanner (SOMATOM Definition AS+, Siemens Healthcare) using a two-pump injector (Medrad Stellant). Both protocols used Siemens' proprietary tube current and tube voltage modulation techniques (CARE dose and CARE kV). The protocols were compared retrospectively to assess the dose-length product (DLP), aortic radiodensity at the level of the coeliac axis and radiodensity of the portal vein. There were 151 trauma CT examinations during this period. Seventy-eight used the split-bolus protocol. Seventy-one had traditional two-phase imaging. One patient was excluded as they were under the age of 18 years. The radiodensity measurements for the portal vein were significantly higher (p<0.001) in the split-bolus protocol. The mean aortic enhancement in both protocols exceeded 250 HU, although the traditional two-phase protocol gave greater arterial enhancement (p<0.001) than the split-bolus protocol. The split-bolus protocol had a significantly lower (p<0.001) DLP with 43.5% reduction in the mean DLP compared to the traditional protocol. Split-bolus CT imaging offers significant dose reduction for this relatively young population while retaining both arterial and venous enhancement.

Dual Energy Computerized Tomography with a Split Bolus—A 1-Stop Shop for Patients with Suspected Urinary Stones?

We evaluated a dual energy, split bolus computerized tomography protocol that provides virtual noncontrast, parenchymal and urographic phases in a single scan. We assessed the sensitivity of the virtual noncontrast phase using this protocol to detect urinary stones compared to the gold standard of the true noncontrast phase. We prospectively enrolled in the study 81 patients who underwent unenhanced single energy computerized tomography at 120 kV/200 mA as well as contrast enhanced dual energy computerized tomography on a Somatom® Definition Flash-CT (tube A 80 kV/233 mA and tube B SN 140 kV/180 mA with 1/0.8 mm slice thickness). For the split bolus protocol 400 mg/ml Iomeron® were injected at 2 time points, that is 15 ml 10 minutes before the scan and 80 ml 65 seconds before the scan. In a consensus reading 2 readers evaluated the presence and diameter of stones on the true and virtual noncontrast phases. Of the 350 stones noted on the true noncontrast phase we found 289 on the virtual noncontrast phase as well as 13 false-positive and 66 false-negative stones. Sensitivity was 98.4%, 89.8% and 82.6% per patient, segment and stone, respectively. The diameter measured on the virtual noncontrast phase corresponded to a mean ± SD 92.5% ± 31.6% of the diameter on the true noncontrast phase. The mean effective dose was 4.8 ± 1.8 and 10.5 ± 3.7 mSv for the true and virtual noncontrast phases, respectively. The proposed protocol allows for combining 3 phases in a single scan while still enabling the detection of urinary stones at high sensitivity. This technique halves the radiation dose and provides the surgeon with better anatomical information on the calyceal system. Therefore, it is a valuable diagnostic tool for kidney stone treatment planning and followup.

Split-Bolus Spectral Multidetector CT of the Pancreas: Assessment of Radiation Dose and Tumor Conspicuity

To assess tumor conspicuity and radiation dose with a new multidetector computed tomography (CT) protocol for pancreatic imaging that combines spectral CT and split-bolus injection. This study was approved by the institutional review board and compliant with HIPAA. The requirement for informed consent was waived. One hundred sixty-three consecutive patients referred for possible pancreatic mass underwent CT with either a standard or split-bolus spectral CT protocol depending on scanner availability. Split-bolus spectral CT (CT unit with spectral imaging) combines pancreatic and portal venous phases in a single scan: 70 seconds before CT, 100 mL of contrast material is injected for the portal venous phase followed approximately 35 seconds later by injection of 40 mL of contrast material to boost the pancreatic phase. Bolus tracking after the second bolus initiates scanning 15 seconds after aorta enhancement reaches 280 HU. Images were reconstructed at 60 and 77 keV. The standard protocol (64-detector row unit) included unenhanced and pancreatic and portal venous phase imaging, with a single contrast material injection timed with bolus tracking 15 seconds after aortic enhancement of 300 HU for the pancreatic phase and 32 seconds later for the portal venous phase. Tumor conspicuity (difference in attenuation between tumor and pancreatic parenchyma) and contrast-to-noise ratio (CNR) were determined. Attenuation of aorta, main portal vein, and liver were measured. Patient size and per-examination radiation dose were recorded. The heteroscedastic t test, Fisher exact test, and Mann-Whitney test were used for statistical analysis. There were no significant differences in age, weight, and body mass index between patients in the standard CT (46 of 80 patients had lesions) and split-bolus spectral CT (39 of 83 patients had lesions) groups; however, there were significantly more women in the split-bolus group (P = .02). Tumor conspicuity and CNR were higher with the 60-keV split-bolus protocol (89.1 HU ± 56.6 and 8.8 ± 6.2, respectively) than with the pancreatic or portal venous phase of the standard protocol (43.5 HU ± 28.4 and 4.5 ± 3.0, and 51.5 HU ± 30.3 and 5.6 ± 4.0, respectively; P < .01 for all comparisons). Dose-length product was 1112 mGy · cm ± 437 with the standard protocol and 633 mGy · cm ± 105 with the split-bolus protocol (P < .001). Split-bolus spectral multidetector CT resulted in vascular, liver, and pancreatic attenuation and tumor conspicuity equal to or greater than that with multiphase CT, with a 43% reduction in radiation dose.