CO2-based C-arm computed tomography (CACT) of the pelvic arteries: feasibility and diagnostic performance in comparison to CO2-angiography in patients with peripheral arterial disease.

BACKGROUND: Patients with substantially impaired kidney function and peripheral arterial disease (PAD) underwent comparative CO2-based depiction of the pelvic arteries (PAs). PURPOSE: To evaluate the feasibility and diagnostic performance of CO2-based C-arm computed tomography (CACT) and compare its depiction of PAs with CO2-digital subtraction angiography (DSA). MATERIAL AND METHODS: Fifteen patients (10 men, mean age 70 ± 11 years) with PAD received CO2-DSA and CO2-CACT of the PAs, depicted from the aorta to femoral arteries. These were divided into nine segments (135 in total) and graded by two independent readers for image quality (IQ; 1 = sufficient, 2 = minimal impairments, 3 = insufficient, 4 = outside field of view) and subsequent stenosis grading (SG; grade 1: normal to grade 4: occlusion), under exclusion of all segments with insufficient IQ. Inter-observer and inter-modality agreement calculation and subsequent consensus reading were performed and correlated to a standard of reference (StOR), representing a modality consensus. RESULTS: Of 135 segments, 117 showed sufficient IQ, excluding 18 segments (10 CACT, 8 DSA). Inter-observer agreement for IQ and consecutive SG demonstrated good to excellent agreement: IQDSA: κ = 0.83, IQCACT: κ = 0.76; StenosisDSA: κ = 0.71, StenosisCACT: κ = 0.84. Inter-modality agreement for SG lay at κ = 0.76 and κ = 0.65, respectively. More stenoses could be detected by CACT, and analysis of pooled consensus values of SG in CACTcons versus StOR showed an excellent agreement (κ = 0.96) that proved considerably higher than the moderate agreement between consensus values in DSAcons versus StOR (κ = 0.43). CONCLUSION: CO2-CACT proved feasible, and has the potential to optimize angiographic work-up of PAD in patients with contraindications for other contrast media.

[Initial Clinical Experience with Dynamic C-arm CT Perfusion Acquisitions].

PURPOSE: Dynamic C-arm computed tomography perfusion (C-arm CTP) is a newly developed application that can provide cerebral perfusion images in the angio suite, similar to conventional multi-detector CTP in a diagnostic room. We introduce the workflow of C-arm CTP acquisition and our initial experience in a clinical setting. METHOD: C-arm CTP was acquired with 40 ml of non-diluted contrast medium injected at 4 ml/s in the median cubital vein followed by 30 ml of saline injected at the same rate. The injection began 5 seconds after the acquisition was started. Two mask runs were followed with eight successive fill runs. Arterial input function was automatically calculated to deliver perfusion maps. Incidence of acquisition errors was evaluated in two phases. RESULT: C-arm CTP images were successfully acquired in all cases, and the images provided useful information under a stable examination protocol. However, we experienced some operational and systematic artifacts that degraded image quality of perfusion maps in Phase 1. The incident rate of errors was significantly improved in Phase 2. CONCLUSION: C-arm CTP acquisitions were feasible during acute stroke treatment in the angio suite. It is expected that the image quality will be further improved through process improvement and reconstruction setting optimization to minimize unexpected artifacts in individual cases.

Reduced-dose C-arm computed tomography applications at a pediatric institution.

BACKGROUND: Reduced-dose C-arm computed tomography (CT) uses flat-panel detectors to acquire real-time 3-D images in the interventional radiology suite to assist with anatomical localization and procedure planning. OBJECTIVE: To describe dose-reduction techniques for C-arm CT at a pediatric institution and to provide guidance for implementation. MATERIALS AND METHODS: We conducted a 5-year retrospective study on procedures using an institution-specific reduced-dose protocol: 5 or 8 s Dyna Rotation, 248/396 projection images/acquisition and 0.1-0.17 µGy/projection dose at the detector with 0.3/0.6/0.9-mm copper (Cu) filtration. We categorized cases by procedure type and average patient age and calculated C-arm CT and total dose area product (DAP). RESULTS: Two hundred twenty-two C-arm CT-guided procedures were performed with a dose-reduction protocol. The most common procedures were temporomandibular and sacroiliac joint injections (48.6%) and sclerotherapy (34.2%). C-arm CT was utilized in cases of difficult percutaneous access in less common applications such as cecostomy and gastrostomy placement, foreign body retrieval and thoracentesis. C-arm CT accounted for between 9.9% and 80.7% of the total procedural DAP. CONCLUSION: Dose-reducing techniques can preserve image quality for intervention while reducing radiation exposure to the child. This technology has multiple applications within pediatric interventional radiology and can be considered as an adjunctive imaging tool in a variety of procedures, particularly when percutaneous access is challenging despite routine fluoroscopic or ultrasound guidance.

Clinical role of guidance by C-arm CT for 125I brachytherapy on pulmonary tumors.

PURPOSE: To evaluate the clinical value of C-arm CT (CACT)-guided interstitial iodine-125 (125I) brachytherapy on pulmonary tumors. MATERIALS AND METHODS: 30 patients with 40 solid pulmonary tumors were enrolled to undergo CACT-guided interstitial 125I brachytherapy between November 2011 and November 2014. The needle path was planned on a CACT virtual navigation and real-time fluoroscopy system. Technical success, puncture score, procedure time, local control rate (LCR), radiation exposure, complications and survival were investigated. RESULTS: The technical success of interstitial 125I brachytherapy under CACT guidance was 40/40 (100%). The performance score was 4.7 ± 0.5 with a mean total procedure time of 17.7 ± 5.6 min. LCR in small (≤2.0 cm), intermediate (2.1-4.9 cm) and large (≥5.0 cm) pulmonary tumors was 100, 89.5 and 72.7% at the 4-month follow-up, respectively. The mean effective dose was 10.1 ± 2.8 mSv. Major complications occurred in four patients (13.3%). The mean survival time was 28.4 ± 2.3 months. CONCLUSION: CACT can provide virtual navigation and real-time fluoroscopy synchronously for interstitial 125I seed implantation on pulmonary tumors.

The Value of C-Arm Computed Tomography in Addition to Conventional Digital Subtraction Angiography in the Diagnostic Work-up of Patients with Suspected Chronic Thromboembolic Pulmonary Hypertension: An Update of 300 Patients.

RATIONALE AND OBJECTIVES: To assess the value and possible benefit of combined C-arm computed tomography (CACT) and conventional digital subtraction angiography (DSA) of the pulmonary arteries in the diagnostic work-up of patients with suspected chronic thromboembolic pulmonary hypertension (CTEPH). MATERIALS AND METHODS: We evaluated 308 pulmonary artery angiographies of 308 consecutive patients with suspected CTEPH. Seven patients were excluded because of incomplete imaging. Thus, 301 datasets were included in our study. The pulmonary artery segments and their subsegmental branching were independently evaluated by two readers (R1, R2) using both, DSA and CACT for optimal image quality. Subsequently, the diagnostic findings were compared. Inter-modality and inter-observer agreement were calculated. Consensus reading was done and correlated to a standard of reference, representing the overall consensus of both modalities. Fisher's exact test and Cohen's Kappa were applied. RESULTS: A total of 5719 pulmonary segments were evaluated of which only 28 segments (0.4%) were rated to be nondiagnostic on both, CACT and DSA. Overall, 5640 (98.6%) and 5600 (97.9%) pulmonary segments were rated to be diagnostic in DSA and CACT, respectively. The main causes of nondiagnostic image quality were motion artifacts on both, CACT (R1:81, R2:50) and DSA (R1:60, R2:48). Interobserver agreement was excellent for DSA (κ = 0.9) and CACT (κ = 0.91) and intermodality agreement was substantial (R1: κ = 0.69, R2: κ = 0.77). Compared to standard of reference, the intermodality agreement for CACT was excellent (κ = 0.96), whereas it was inferior for DSA (κ = 0.75), due to the higher number of pathologic findings in CACT read as normal on DSA. CONCLUSION: CACT of the pulmonary arteries can provide additional information to DSA during CTEPH work-up. Moreover, the combination of CACT and DSA can minimize the portion of non-diagnostic examinations, therefore being a reasonable combination to optimize the diagnostic work-up.

Evaluation of a Motion Correction Algorithm for C-Arm Computed Tomography Acquired During Transarterial Chemoembolization.

PURPOSE: The aim of this retrospective study was to evaluate the feasibility of a motion correction 3D reconstruction prototype technique for C-arm computed tomography (CACT). MATERIAL AND METHODS: We included 65 consecutive CACTs acquired during transarterial chemoembolization of 54 patients (47 m,7f; 67 ± 11.3 years). All original raw datasets (CACTOrg) underwent reconstruction with and without volume punching of high-contrast objects using a 3D image reconstruction software to compensate for motion (CACTMC_bone;CACTMC_no bone). Subsequently, the effect on image quality (IQ) was evaluated using objective (image sharpness metric) and subjective criteria. Subjective criteria were defined by vessel geometry, overall IQ, delineation of tumor feeders, the presence of foreign material-induced artifacts and need for additional imaging, assessed by two independent readers on a 3-(vessel geometry and overall IQ) or 2-point scale, respectively. Friedman rank-sum test and post hoc analysis in form of pairwise Wilcoxon signed-rank test were computed and inter-observer agreement analyzed using kappa test. RESULTS: Objective IQ as defined by an image sharpness metric, increased from 273.5 ± 28 (CACTOrg) to 328.5 ± 55.1 (CACTMC_bone) and 331 ± 57.8 (CACTMC_no bone; all p < 0.0001). These results could largely be confirmed by the subjective analysis, which demonstrated predominantly good and moderate inter-observer agreement, with best agreement for CACTMC_no bone in all categories (e.g., vessel geometry: CACTOrg: κ = 0.51, CACTMC_bone: κ = 0.42, CACTMC_no bone: κ = 0.69). CONCLUSION: The application of a motion correction algorithm was feasible for all data sets and led to an increase in both objective and subjective IQ parameters. LEVEL OF EVIDENCE: 3.

Comparison of the Uptake of Hepatocellular Carcinoma on Pre-Therapeutic MDCT, CACT, and SPECT/CT, and the Correlation with Post-Therapeutic PET/CT in Patients Undergoing Selective Internal Radiation Therapy.

(1) Background: To comparatively analyze the uptake of hepatocellular carcinoma (HCC) on pre-therapeutic imaging modalities, the arterial phase multi-detector computed tomography (MDCT), the parenchymal phase C-arm computed tomography (CACT), the Technetium99m-macroaggregates of human serum albumin single-photon emission computed tomography/computed tomography (SPECT/CT), and the correlation to the post-therapeutic Yttrium90 positron emission tomography/computed tomography (PET/CT) in patients with selective internal radiation therapy (SIRT). (2) Methods: Between September 2013 and December 2016, 104 SIRT procedures were performed at our institution in 74 patients with HCC not suitable for curative surgery or ablation. Twenty-two patients underwent an identical sequence of pre-therapeutic MDCT, CACT, SPECT/CT, and post-therapeutic PET/CT with a standardized diagnostic and therapeutic protocol. In these 22 patients, 25 SIRT procedures were evaluated. The uptake of the HCC was assessed using tumor-background ratio (TBR). Therefore, regions of interest were placed on the tumor and the adjacent liver tissue on MDCT (TBRMDCT), CACT (TBRCACT), SPECT/CT (TBRSPECT/CT), and PET/CT (TBRPET/CT). Comparisons were made with the Friedman test and the Nemenyi post-hoc test. Correlations were analyzed using Spearman's Rho and the Benjamini-Hochberg method. The level of significance was p < 0.05. (3) Results: TBR on MDCT (1.4 ± 0.3) was significantly smaller than on CACT (1.9 ± 0.6) and both were significantly smaller compared to SPECT/CT (4.6 ± 2.0) (pFriedman-Test < 0.001; pTBRMDCT/TBRCACT = 0.012, pTBRMDCT/TBRSPECT/CT < 0.001, pTBRCACT/TBRSPECT/CT < 0.001). There was no significant correlation of TBR on MDCT with PET/CT (rTBRMDCT/TBRPET/CT = 0.116; p = 0.534). In contrast, TBR on CACT correlated to TBR on SPECT/CT (rTBRCACT/TBRSPECT/CT = 0.489; p = 0.004) and tended to correlate to TBR on PET/CT (rTBRCACT/TBRPET/CT =0.365; p = 0.043). TBR on SPECT/CT correlated to TBR on PET/CT (rTBRSPECT/CT/TBRPET/CT = 0.706; p < 0.001) (4) Conclusion: The uptake assessment on CACT was in agreement with SPECT/CT and might be consistent with PET/CT. In contrast, MDCT was not comparable to CACT and SPECT/CT, and had no correlation with PET/CT due to the different application techniques. This emphasizes the value of the CACT, which has the potential to improve the dosimetric assessment of the tumor and liver uptake for SIRT.

Evaluation of Cerebral Hyperperfusion After Carotid Artery Stenting Using C­Arm CT Measurements of Cerebral Blood Volume.

PURPOSE: Hyperperfusion syndrome (HPS) after carotid artery stenting (CAS) causes serious symptoms; therefore, early evaluation after CAS is considered to be important. Measurement of cerebral blood volume using C­arm computed tomography (C-arm CBV) has recently become possible. Here, the usefulness of C­arm CBV for the evaluation of hyperperfusion was investigated. METHODS: C-arm CBV was measured before and immediately after CAS in 30 patients. The regions of interest (ROI) were set in the bilateral middle cerebral artery perfused regions, and the affected/healthy side ratio of measured C­arm CBV (CBV ratios) was determined to evaluate cerebral perfusion. For comparing values before and after CAS, the CBV ratio increase rate (postoperative CBV ratios/preoperative CBV ratios) was also determined. RESULTS: C-arm CBV was successfully measured in 30 patients. Intracerebral hemorrhage (ICH) was detected in 3 patients, and no other patient had hyperperfusion syndrome. In the patients who developed ICH, postoperative C­arm CBV on the affected side was high, and a marked increase was confirmed in the postoperative CBV ratios. Postoperative CBV ratios were 1.03 ± 0.40 and 1.45 ± 0.68 in the non-ICH and ICH groups, and CBV ratio increase rates were 2.7 ± 24.0% and 28.5 ± 26.7% in the non-ICH and ICH groups, respectively; these differences were statistically significant (P < 0.01). CONCLUSION: C-arm CT allows CBV measurements immediately after CAS without requiring transport of the patient out of the angiography room, and it may enable the evaluation of hyperperfusion before and after CAS.

Image quality of arterial phase and parenchymal blood volume (PBV) maps derived from C-arm computed tomography in the evaluation of transarterial chemoembolization.

BACKGROUND: To evaluate the benefits of arterial phase imaging and parenchymal blood volume (PBV) maps acquired by C-arm computed tomography during TACE procedure in comparison to cross-sectional imaging (CSI) using CT or MRI. METHODS: From January 2014 to December 2016, a total of 29 patients with HCC stage A or B (mean age 65 years; range 47 to 81 years, 86% male) were included in this study. These patients were referred to our department for TACE treatment and received peri-interventional C-arm CT. Dual phase findings of each lesion in terms of overall image quality, conspicuity, tumor size and feeding arteries were compared between arterial phase imaging and PBV using 5-point semi-quantitative Likert-scale, whereby pre-interventional CSI served as reference standard. RESULTS: A significantly higher overall image quality of the PBV maps compared to arterial phase C-arm CT acquisitions (4.34 (±0.55) vs. 3.93 (±0.59), p = 0.0032) as well as a higher conspicuity of HCC lesions (4.27 ± 0.74 vs. 3.83 ± 1.08, p < 0.0001) was observed. Arterial phase imaging led to an overestimation of tumor size (mean size, 26.5 ± 15.9 mm) compared to PBV (24.9 ± 15.2 mm, p = 0.0004) as well as CSI (25.2 ± 15.1 mm), p = 0.021). Regarding detectability of tumor feeding arterial vessels, significantly more feeding vessels were detected in arterial phase C-arm CT (n = 1.67 ± 0.92 vessels) compared to PBV maps (n = 1.27 ± 0.63 vessels) (p = 0.0001). One lesion was missed in pre-interventional CT imaging, but detected by C-arm CT. CONCLUSION: The combination of PBV maps and arterial phase images acquired by C-arm CT during TACE procedure enables precise detection of the majority of HCC lesions and tumor feeding arteries and has therefore the potential to improve patient outcome.

Use of short roll C-arm computed tomography and fully automated 3D analysis tools to guide transcatheter aortic valve replacement.

Determination of the coplanar view is a critical component of transcatheter aortic valve replacement (TAVR). The safety and accuracy of a novel reduced angular range C-arm computed tomography (CACT) approach coupled with a fully automated 3D analysis tool package to predict the coplanar view in TAVR was evaluated. Fifty-seven patients with severe symptomatic aortic stenosis deemed prohibitive-risk for surgery and who underwent TAVR were enrolled. Patients were randomized 2:1 to CACT vs. angiography (control) in estimating the coplanar view. These approaches to determine the coplanar view were compared quantitatively. Radiation doses needed to determine the coplanar view were recorded for both the CACT and control patients. Use of CACT offered good agreement with the actual angiographic view utilized during TAVR in 34 out of 41 cases in which a CACT scan was performed (83 %). For these 34 cases, the mean angular magnitude difference, taking into account both oblique and cranial/caudal angulation, was 1.3° ± 0.4°, while the maximum difference was 7.3°. There were no significant differences in the mean total radiation dose delivered to patients between the CACT and control groups as measured by either dose area product (207.8 ± 15.2 Gy cm(2) vs. 186.1 ± 25.3 Gy cm(2), P = 0.47) or air kerma (1287.6 ± 117.7 mGy vs. 1098.9 ± 143.8 mGy, P = 0.32). Use of reduced-angular range CACT coupled with fully automated 3D analysis tools is a safe, practical, and feasible method by which to determine the optimal angiographic deployment view for guiding TAVR procedures.

Comparison of C-arm Computed Tomography and Digital Subtraction Angiography in Patients with Chronic Thromboembolic Pulmonary Hypertension.

PURPOSE: To assess the feasibility and diagnostic performance of contrast-enhanced, C-arm computed tomography (CACT) of the pulmonary arteries compared to digital subtraction angiography (DSA) in patients suffering from chronic thromboembolic pulmonary hypertension (CTEPH). MATERIALS: Fifty-two patients with CTEPH underwent ECG-gated DSA and contrast-enhanced CACT. Two readers (R1, R2) independently evaluated pulmonary artery segments and their sub-segmental branching using DSA and CACT for optimal image quality. Afterwards, the diagnostic findings, i.e., intraluminal filling defects, stenosis, and occlusion, were compared. Inter-modality and inter-observer agreement was calculated, and subsequently consensus reading was done and correlated to a reference standard representing the overall consensus of both modalities. Fisher's exact test and Cohen's Kappa were applied. RESULTS: A total of 1352 pulmonary segments were evaluated, of which 1255 (92.8 %) on DSA and 1256 (92.9 %) on CACT were rated to be fully diagnostic. The main causes of the non-diagnostic image quality were motion artifacts on CACT (R1:37, R2:78) and insufficient contrast enhancement on DSA (R1:59, R2:38). Inter-observer agreement was good for DSA (κ = 0.74) and CACT (κ = 0.75), while inter-modality agreement was moderate (R1: κ = 0.46, R2: κ = 0.47). Compared to the reference standard, the inter-modality agreement for CACT was excellent (κ = 0.96), whereas it was inferior for DSA (κ = 0.61) due to the higher number of abnormal consensus findings read as normal on DSA. CONCLUSION: CACT of the pulmonary arteries is feasible and provides additional information to DSA. CACT has the potential to improve the diagnostic work-up of patients with CTEPH and may be particularly useful prior to surgical or interventional treatment.

C-arm computed tomography and volume perfusion computed tomography (VPCT)-based assessment of blood volume changes in hepatocellular carcinoma in prediction of midterm tumor response to transarterial chemoembolization: a single center retrospective trial.

BACKGROUND: This study aims to evaluate immediate changes in perfusion parameters in hepatocellular carcinoma (HCC) to transarterial chemoembolization (TACE) in C-arm computed tomography (CT) and volume perfusion CT (VPCT) and prediction of midterm tumor response. METHODS: Twenty-five patients (median age 66, range 61 to 75 years) with 62 HCC lesions undergoing TACE received immediate pre- and post-interventional assessment by C-arm CT and VPCT. Cross-sectional imaging was analyzed at baseline and approximately 12 weeks after TACE according to modified RECIST criteria. Outcome was defined as objective response (OR, > 30 % reduction of viable tumor) or non-OR. Perfusion parameters were evaluated in C-arm CT [parenchymal blood volume (PBV)] and VPCT [blood volume (BV) and blood flow (BF)]. Ratios of perfusion parameters before and after TACE within the tumor and the non-affected liver parenchyma were calculated. RESULTS: Correlation between tumor PBV and BV revealed a moderate correlation (rho = 0.45, p = 0.005). In non-affected liver parenchyma, a significant decrease in PBV was seen, compared to a significant increase in BF and BV. Perfusion ratios in HCC lesions were significantly (p < 0.05) increased in OR group compared to non-OR patients in C-arm CT and VPCT: PBV ratio (0.95 (0.06) to 0.67 (0.38), BV ratio 0.63 (0.34) to 0.15 (0.6), and BF ratio 0.6 (0.32) to 0.22 (0.51). Logistic regression including PBV and BF allowed prediction of OR (sensitivity 88 %/specificity of 83 %). CONCLUSIONS: Perfusion parameters acquired by C-arm CT and VPCT cannot simply be substituted by each other, but show similar capability in prediction of midterm tumor response.

C-arm Lipiodol CT in transcatheter arterial chemoembolization for small hepatocellular carcinoma.

AIM: To investigate the value of C-arm Lipiodol computed tomography (CT) for intra-procedural hepatocellular carcinoma (HCC) lesion detection during transcatheter arterial chemoembolization (TACE). METHODS: Forty patients (37 male, 3 female; mean age, 52.6 ± 12.5 years, age range: 25-82 years) diagnosed with HCC were enrolled in this study. All patients underwent 64-slice CT 1-2 wk before TACE. During the procedure, hepatic angiography was performed first. Following diagnostic embolization with Lipiodol injected into the hepatic artery, a C-arm CT scan was immediately conducted (C-arm Lipiodol CT). If new HCC lesions were confirmed, gelfoam particles were super-selectively injected into the tumor-nourishing blood vessel. A Lipiodol CT scan was performed 7-14 d after TACE. All images acquired from 64-slice CT, digital subtraction angiography (DSA), C-arm Lipiodol CT and Lipiodol CT were retrospectively reviewed by four radiologists and the number of detected lesions in each examination was counted, respectively. The results of Lipiodol CT were taken as the diagnostic reference. Alpha-fetoprotein values were examined both before and after TACE. This study only takes into account the lesions that were not found or were considered suspicious on 64-slice CT before TACE. RESULTS: Preprocedural 64-slice CT detected a total of 13 suspicious lesions in the 40 patients. DSA detected ten definite and four suspicious lesions. C-arm Lipiodol CT detected 71 lesions in total and Lipiodol CT confirmed 67 lesions with a diameter range of 3-12 mm. Four false-positive lesions, which were detected by C-arm Lipiodol CT, were considered to be hepatic artery-portal vein fistulas. The average alpha-fetoprotein values before and after TACE were significantly different (452.3 ± 192.6 ng/mL vs 223.8 ± 93.2 ng/mL; P = 0.039). CONCLUSION: C-arm Lipiodol CT has a higher diagnostic sensitivity for small HCC lesions. This technique may help physicians make intraprocedural decisions to provide patients with earlier treatment.

Percutaneous Paravalvular Leak Closure.

Symptomatic paravalvular leak (PVL) complicates up to 12 % of surgical valve replacements. When patients present with congestive heart failure and/or haemolysis, reoperation for repeat valve replacement may be undertaken, but presents greater risk and lower likelihood of success than the initial operation. Therefore, percutaneous approaches to PVL closure have been developed by specialists in structural cardiac intervention. Large series demonstrate high levels of procedural success and promising clinical outcomes for this complex intervention. A thorough understanding of multimodality imaging is necessary for the diagnosis of PVL and the safe and successful performance of these closure procedures.