Parametric Color Coding Research Articles

Parametric Color Coding of Digital Subtraction Angiography in the Evaluation of the Type B Chronic Aortic Dissection During Tevar: A Preliminary Study

Introduction - Angiografic assessment of type B chronic aortic dissection (TBCAD) can be complex in TEVAR procedures, due to the presence of true and false lumen. Quantitative digital subtraction angiography (Q-DSA) with a parametric color-coding provides a novel approach for encoding temporal information and enabling quantitative measurements. (1,2) The potential value of the use of color in the display of these parametric images was recognized (3), particularly useful in situations in which there is a complex flow pattern. (4,5) The aim of this study was to evaluate whether the use of parametric color-coding in the post processing of DSA series is advantageous in the evaluation of TBCAD during TEVAR procedures. Methods - We enrolled 11 patients treated electively for a TBCAD. All cases were treated with TEVAR for a aneurysm disease of thoracic descending aorta (> 6 cm) with the coverture of proximal entry tear. For postprocessing of digital subtraction angiography (DSA) series, a newly implemented algorithm of parametric color-coding was used, turning sequential images of two-dimensional (2D)-DSA series into a single color-coded image (Syngo I-Flow, Siemens AG, Forchheim, Germany). In consensus reading, two experienced vascular surgeons valuated the initial, interventional, and post-interventional 2D-DSA series comparing them to the color-coded images, respectively. Whether parametric color-coding could facilitate evaluation of a true and false lumen and provide a more precise estimation of proximal entry tear as well as whether flow analysis could reveal objective changes during and after TEVAR treatment were investigated. Results - In 81.8 % of the cases, parametric color coding was observed to facilitate visualization of the aortic dissection angioarchitecture in term of true e false lumen contemporary vision. Estimation of proximal entry tear was considered to be improved in 45.4 % of the cases (fig. 1. maximum intensity peak DSA (a) and parametric color elaboration with entry tear enhanced (b)). For assessment of hemodynamic changes during and after treatment, parametric color coding was assumed to be helpful in 36.3 % of the cases, especially because revealing flow changes that were not visible on 2D-DSA series were now visible. Conclusion - Without additional cost in term of x-ray and contrast medium exposure, parametric color-coding is a real time application tool that might provide additional support in the angiographic evaluation of TBCAD during TEVAR. Visualization of complex aortic dissection architecture could be facilitated, and flow analysis might improve assessment of entry tear position, thereby increasing overall diagnostic confidence. During and after treatment, hemodynamic changes that were not visible on 2D-DSA series could now be depicted.

Ultraearly assessed reperfusion status after middle cerebral artery recanalization predicting clinical outcome.

Mechanical thrombectomy has high evidence in stroke therapy; however, successful recanalization guarantees not a favorable clinical outcome. We aimed to quantitatively assess the reperfusion status ultraearly after successful middle cerebral artery (MCA) recanalization to identify flow parameters that potentially allow predicting clinical outcome. Sixty-seven stroke patients with acute MCA occlusion, undergoing recanalization, were enrolled. Using parametric color coding, a post-processing algorithm, pre-, and post-interventional digital subtraction angiography series were evaluated concerning the following parameters: pre- and post-procedural cortical relative time to peak (rTTP) of MCA territory, reperfusion time, and index. Functional long-term outcome was assessed by the 90-day modified Rankin Scale score (mRS; favorable: 0-2). Cortical rTTP was significantly shorter before (3.33±1.36seconds; P=.03) and after intervention (2.05±0.70seconds; P=.003) in patients with favorable clinical outcome. Additionally, age (P=.005) and initial National Institutes of Health Stroke Scale score (P=.02) were significantly different between the patients, whereas reperfusion index and time as well as initially estimated infarct size were not. In multivariate analysis, only post-procedural rTTP (P=.005) was independently associated with favorable clinical outcome. 2.29seconds for post-procedural rTTP might be a threshold to predict favorable clinical outcome. Ultraearly quantitative assessment of reperfusion status after successful MCA recanalization reveals post-procedural cortical rTTP as possible independent prognostic value in predicting favorable clinical outcome, even determining a threshold value might be possible. In consequence, focusing stroke therapy on microcirculatory patency could be valuable to improve outcome.

The potential role of quantitative digital subtraction angiography in evaluating type B chronic aortic dissection during TEVAR: preliminary results.

To evaluate the role of quantitative digital subtraction angiography (Q-DSA) with parametric color coding (PCC) in assessing patients with type B chronic thoracic aortic dissection (TBCAD) during thoracic endovascular aortic repair (TEVAR) procedures. A total of 11 patients electively treated in our Department for a TBCAD were retrospectively enrolled. All cases were treated with TEVAR for false lumen aneurysm of the thoracic descending aorta. For digital subtraction angiography (DSA) series post-processing, a newly implemented PCC algorithm was used to turn consecutive two-dimensional images into a single color-coded picture (syngo iFLOW, Siemens AG, Forchheim, Germany). In consensus reading, two clinicians experienced in vascular imaging evaluated the DSA series in blinded assessment and compared them to the color-coded images. PCC was assessed for its accuracy in identifying the true and false lumen as well as whether it could provide improved visualization in pre-deployment stent grafting and the final evaluation of treatment. PCC facilitated the visualization of the aortic dissection angioarchitecture in terms of contemporary true and false lumen vision in 81.8% of the cases. In 72.7% of the procedures, Q-DSA was estimated to improve aorta information assessment in terms of false lumen viewing, and it was possible to identify the proximal entry tear position in 45.4% of the cases. After stent graft deployment, in 72.7% of the cases (all 8 patients in which the aortic arch false lumen was visible in pre-treatment), Q-DSA confirmed the absence of early false lumen reperfusion. Our results indicate that Q-DSA could be useful in the intraprocedural evaluation of patients with aortic dissection during TEVAR procedures without additional x-ray costs and contrast exposure.

Ultra-early Detection of Microcirculatory Injury as Predictor of Developing Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage.

Delayed cerebral ischemia (DCI) still remains amajor complication after subarachnoid hemorrhage (SAH). The aim of our study was to evaluate whether flow analysis of admission digital subtraction angiography (DSA) using parametric color coding (PCC), apostprocessing algorithm, allows ultra-early identification of SAH patients at risk for developing subsequent symptomatic vasospasm. In this study 52patients who suffered SAH from aneurysm rupture, were retrospectively enrolled. Of the patients 26 developed DCI and angiographically proven cerebral vasospasm and 26age, gender-and clinical status-matched SAH patients without DCI served as controls. Using PCC, the following flow parameters were calculated: cerebral circulation time (CirT), cortical relative time to peak (rTTP) and microvascular transit time (TT). Mean cerebral CirT and cortical rTTP were longer in the DCI group (6.42 s± 1.54 and 3.16 s± 0.86, respectively) than in the non-DCI group (5.77 s± 1.86 and 3.11 s± 1.41, respectively), but without statistical significance. The mean microvascular TT was statistically significantly (p= 0.04) longer in the DCI group (3.19 s± 0.78) than in the non-DCI group (2.67 s± 0.73). Angiographic flow analysis might be suitable for ultra-early detection and quantitative assessment of microcirculatory injury in SAH patients, predictive of developing subsequent DCI. Prolonged microvascular TT seems to be asignificant independent factor positively associated with DCI development. Identifying SAH patients at risk for DCI ultra-early after ictus might contribute to initiate prophylactic therapies before clinical deterioration.

Treatment Evaluation of Flow-Limiting Stenoses of the Superficial Femoral and Popliteal Artery by Parametric Color-Coding Analysis of Digital Subtraction Angiography Series.

To evaluate the hemodynamic effect of percutaneous transluminal intervention (PTI) on stenosis of the superficial femoral (SFA) and popliteal arteries (PA) using time-density curves (TDCs) derived from digital subtraction angiography (DSA) series in correlation with ultrasound peak systolic velocity ratio (PSVR) and ankle brachial index (ABI). DSA series of SFA or PA of patients with symptomatic peripheral arterial occlusive disease was obtained with a flat-panel angiography system with intention-to-treat. In DSA series acquired before and after PTI, TDCs were analyzed proximal and distal of each stenosis using parametric color coding (PCC). For correlation, ABI and PSVR measurements pre- and post-PTI were recorded for all patients. In total, 25 stenoses of the SFA or PA were treated by PTI in 22 patients (17 male, 5 female, mean age 68 years). After treatment, peak-to-peak (PTP) times between TDCs proximal and distal to the treated vessel segment decreased statistically significantly (p=0.01) on average from PTP=1.9±1.7s to mean PTP=1±1s. ABI and PSVR also changed statistically significantly after treatment (pretreatment ABI=0.7±0.2, PSVR=4.2±1.9; post-ABI=0.9±0.2, PSVR=1.3±0.4, both p<0.05). Correlation parameters did not show a strong correlation between change in TDC and clinical parameters ABI and PSVR. Using PCC for analyzing contrast medium dynamics in DSA series is clinically useful for evaluating stenoses of the SFA and PA and for immediate treatment control after PTA. Case series, IV.

Real-Time, In Vivo Monitoring, and Quantitative Assessment of Intra-Arterial Vasospasm Therapy.

Our study aimed to evaluate whether the effect of an intra-arterial vasospasm therapy can be assessed quantitatively by in vivo blood flow analysis using the postprocessing algorithm parametric color coding (PCC). We evaluated 17 patients presenting with acute clinical deterioration due to vasospasm following subarachnoidal hemorrhage treated with intra-arterial nimodipine application. Pre- and post-interventional DSA series were post-processed by PCC. The relative time to maximum opacification (rTmax) was calculated in 14 arterially and venously located points of interest. From that data, the pre- and post-interventional cerebral circulation time (CirT) was calculated. Additionally, the arterial vessel diameters were measured. Pre- and post-interventional values were compared and tested for significance, respectively. Flow analysis revealed in all arterial vessel segments a non-statistically significant prolongation of rTmax after treatment. The mean CirT was 5.62s (±1.19s) pre-interventionally and 5.16s (±0.81s) post-interventionally, and the difference turned out as statistically significant (p=0.039). A significantly increased diameter was measurable in all arterial segments post-interventionally. PCC is a fast applicable imaging technique that allows via real-time and in vivo blood flow analysis a quantitative assessment of the effect of intra-arterial vasospasm therapy. Our results seem to validate in vivo that an intra-arterial nimodipine application induces not only vasodilatation of the larger vessels, but also improves the microcirculatory flow, leading to a shortened cerebral CirT that reaches normal range post-interventionally. Procedural monitoring via PCC offers the option to compare quantitatively different therapy regimes, which allows optimization of existing approaches and implementation of individualized treatment strategies.

Flow-diverting stents allow efficient treatment of unruptured, intradural dissecting aneurysms of the vertebral artery: An explanatory approach using in vivo flow analysis

Our study aimed to evaluate the efficiency of flow-diverting stents (FDS) in treating unruptured, intradural dissecting aneurysms of the vertebral artery (VADAs). Additionally, the effect of FDS on the aneurysmal flow pattern was investigated by performing invivo flow analysis using parametric color coding (PCC). We evaluated 11 patients with unruptured, intradural VADAs, treated with FDS. Pre- and postinterventional DSA-series were postprocessed by PCC, and time-density curves were calculated. The parameters aneurysmal inflow-velocity, outflow-velocity and relative time-to-peak (rTTP) were calculated. Pre- and postinterventional values were compared and correlated with the occlusion rate after six months. Follow-up DSA detected 10 aneurysms occluded, meaning an occlusion rate of 91%. No procedure-related morbidity and mortality was found. Flow analyses revealed a significant reduction of aneurysmal inflow- velocity and prolongation of rTTP after FDS deployment. Concerning aneurysm occlusion, the postinterventional outflow-velocity turned out to be a marginally statistically significant predictor. A definite threshold value (-0.7 density change/s) could be determined for the outflow-velocity that allows prediction of complete aneurysm occlusion with high sensitivity and specificity (100%). Using FDS can be considered an efficient and safe therapy option in treating unruptured, intradural VADA. From invivo flow analyses the postinterventional aneurysmal outflow-velocity turned out to be a potential predictor for later complete aneurysm occlusion. Here, it might be possible to determine a threshold value that allows prediction of aneurysm occlusion with high specificity and sensitivity. As fast, applicable and easy-to-handle tool, PCC could be used for procedural monitoring and might contribute to further treatment optimization.

Clinical values of hemodynamics assessment by parametric color coding of digital subtraction angiography before and after endovascular therapy for critical limb ischaemia

To investigate the feasibility of parametric color coding of digital subtraction angiography (Syngo iFlow) for hemodynamics assessment in patients with critical limb ischemia in pre- and post-endovascular therapy. To explore the correlation between Syngo iFlow and the conventional techniques. from January 2013 to December 2014, Clinical data of 21 patients with TASC II type B and type C femoropopliteal arteriosclerotic occlusive disease who were treated by percutaneous transluminal angioplasty and/or primary stent implantation in Nanjing first hospital were analyzed retrospectively. Of these patients there were 10 males and 11 females with an average age of (72±6) years (range from 58-85 years). The treatment efficacy was assessed by the variation of a series of clinical symptoms indexes (such as pain score, cold sensation score and intermittent claudication score), ankle braehial index (ABI) and transcutaneous oxygen pressure (TcPO2). Angiography was performed with the same protocol before and after treatment and parametric color coding of digital subtraction angiography was created by Syngo iFlow software on a dedicated workstation. The time to peak (TTP) of artery and tissue perfusion selected at the same regions of foot and ankle were measured and analyzed to evaluate the improvement of microcirculation and hemodynamics of the ischemic limb. The correlations between Syngo iFlow and the traditional clinical evaluation methods were explored using the Spearman rank correlation test. All patients (21 limbs) underwent successful endovaseular therapy. The mean pain score, cold sensation score, intermittent claudication score, ABI and TcPO2 before treatment were (0.48±0.68), (2.71±0.72), (2.86±0.85), ABI (0.33±0.07), TcPO2 (26.83±3.41) mmHg. While 1 week after treatment all above indicators were (2.57±0.93), (0.33±0.48), (0.90±0.54), (0.69±0.11), TcPO2 (53.75±3.60) mmHg respectively. There were significant statistical differences between pre- and post-treatment (P<0.05). The pre- and post-operative TTP of artery and tissue perfusion were (14.07±1.77) vs (10.43±2.05) s, (18.75±2.72) vs (15.38±2.78) s. For assessment of hemodynamic changes during and after treatment, parametric color coding of digital subtraction angiography (Syngo iFlow) was assumed to show the limb blood flow and perfusion were improved and the differences were statistically significant. The Spearman rank correlation test showed the TTP of artery was positively correlated with ABI, TcPO2 (r=0.65, 0.73, P<0.05), the TTP of tissue perfusion was also positively correlated with ABI, TcPO2 (r=0.60, 0.60, P<0.05). Parametric color coding of digital subtraction angiography (Syngo iFlow) is a real-time, sensitive and quantitative tool that might provide additional support in the hemodynamics evaluation of endovascular treatment for patients with lower extremity peripheral arterial occlusion disease.

Monitoring of Balloon Test Occlusion of the Internal Carotid Artery by Parametric Color Coding and Perfusion Imaging Within the Angio Suite: First Results

Temporary balloon test occlusion (BTO) might be performed prior to procedures in which occlusion of the internal carotid artery (ICA) might be necessary. We tested the hypothesis that parametric color coding (PCC) of angiographic series (digital subtraction angiography (DSA)) along with the assessment of cerebral blood volume (CBV) in the angiography suite would simplify and enhance the identification of candidates who are most likely to tolerate occlusion. Fifteen patients underwent angiographic series (DSA) and perfusion imaging before and during BTO. Pre- and postocclusion DSA acquisitions were evaluated for venous delay by conventional methods ("eye balling") and by PCC measurements. Comparison of CBV values between the left and right hemisphere in 6 defined regions was performed. Values of venous delay by eye balling and PCC showed a high correlation (r = 0.87, p < 0.01). Bland-Altman plot indicated slightly lower values (-0.05 s) by the PCC method. One of the 15 patients developed an asymmetrical CBV map with an increase in CBV of more than one standard deviation in 3 of the 6 regions of interest (ROIs). Acquisition of angiographic series and perfusion imaging did not prolong the test occlusion time. PCC and CBV mapping are feasible during BTO. The use of PCC seems to simplify the ability to measure changes in venous filling delay. Perfusion imaging may show an increase in CBV in patients reaching the limits of cerebral autoregulation. These patients may be at risk for delayed infarction, even though they seem to tolerate temporary occlusion, and could be unsuitable candidates for permanent ICA occlusion.

Parametric Color Coding of Digital Subtraction Angiography in the Evaluation of Carotid Cavernous Fistulas

Angiographic assessment of carotid cavernous fistulas (CCFs) can be complex. Our purpose was to examine whether the use of parametric color coding in the postprocessing of DSA series is advantageous in the evaluation of CCFs. We enrolled 16 patients with angiographically proven CCFs. Endovascular treatment was performed in 14 cases. For postprocessing of digital subtraction angiography (DSA) series, a newly implemented algorithm of parametric color coding was used, turning sequential images of two-dimensional (2D)-DSA series into a single color-coded image. Angiographic data of initial, interventional, and postinterventional 2D-DSA series were compared with color-coded images. Whether parametric color coding could facilitate evaluation of fistula architecture and provide a more precise estimation of fistula venous drainage patterns as well as whether flow analysis could reveal objective changes during and after treatment were investigated. In 56 % of the cases, parametric color coding was observed to facilitate visualization of fistula angioarchitecture. Estimation of fistula drainage flow patterns was considered to be improved in 31 % of the cases. For assessment of hemodynamic changes during and after treatment, parametric color coding was assumed to be helpful in 21 % of the cases, especially because revealing flow changes that were not visible on 2D-DSA series were now visible. Parametric color coding is a fast application tool that might provide additional support in the angiographic evaluation of CCFs. Visualization of complex fistula architecture could be facilitated, and flow analysis might improve assessment of venous drainage patterns, thereby increasing overall diagnostic confidence. During and after treatment, hemodynamic changes that were not visible on 2D-DSA series could now be depicted.