Evaluation of Sine Spin flat detector CT imaging compared with multidetector CT

Cochlear implant imaging with accelerated flat panel computed tomography: Image quality and dosimetry comparison to conventional high-resolution multislice computed tomography

Background and PurposeCone-beam CT (CBCT) and high-resolution multislice CT (HR-MSCT) are the mainstay postoperative imaging modalities following cochlear implant (CI) surgery, with CBCT often preferred due to lower susceptibility to metallic artifacts. However, CBCT is more prone to motion artifacts due to longer acquisition times. Recent advancements in accelerated flat panel CT (Acc-FPCT) available with latest generation angiography systems addressed traditional limitations of CBCT by significantly decreasing scan time. This study evaluates the diagnostic performance and radiation dose of Acc-FPCT compared to HR-MSCT in postoperative CI evaluation.MethodsFive cadaveric whole-head specimens (ten temporal bones) were operated on by an ENT surgeon. Ten CIs were inserted via cochleostomy. Post-operatively, specimens were scanned using six Acc-FPCT protocols and HR-MSCT. Three neuroradiologists assessed the image quality of FPCT protocols in comparison to HR-MSCT using a 5-point Likert scale. Seven electrode characteristics including scalar position and discernibility of individual contacts were evaluated. Radiation dose parameters (CTDIvol and DLP) were compared among protocols.ResultsTwo high-resolution Acc-FPCT (HR-FPCT) protocols were rated superior to HR-MSCT (p < .01). There were no significant differences between these two protocols (p = .25). The remaining Acc-FPCT protocols were rated inferior to HR-MSCT (p < .05). Inter-rater reliability was excellent (ICC (2,k) = 0.908; CI [0.85-0.94]). DLP was significantly lower in all Acc-FPCT protocols compared to HR-MSCT.ConclusionsThe results of this study underscore the utility of Acc-FPCT protocols as a feasible alternative to HR-MSCT in postoperative CI evaluation, allowing for better visualization of electrode array while significantly reducing scan duration and radiation exposure.

Accelerated flat panel computed tomography for pre-operative temporal bone imaging: Image quality and dosimetry comparison to conventional high resolution multislice computed tomography

PURPOSE

High-resolution multislice CT (HR-MSCT) and cone beam CT (CBCT) are commonly used for preoperative temporal bone imaging, with HR-MSCT often preferred due to its shorter scan duration and lower susceptibility to motion artifacts. However, recent advancements in accelerated flat panel CT (Acc-FPCT) available with the latest generation angiography systems have addressed traditional limitations of CBCT by significantly decreasing scan time. This cadaver-based study evaluates the diagnostic performance and radiation dose of Acc-FPCT compared to HR-MSCT in preoperative temporal bone imaging.

METHODS

Six different Acc-FPCT protocols were acquired on five whole-head cadaveric specimens (ten temporal bones). Three neuroradiologists experienced in temporal bone imaging assessed the image quality of Acc-FPCT protocols in comparison to that of HR-MSCT for the visualization of 31 landmarks of middle and inner ear using a 5-point Likert scale. We also compared radiation dose parameters (CT dose index and dose length product) among the protocols.

RESULTS

Two high-Resolution Acc-FPCT protocols were found to be superior to HR-MSCT by all raters (p < 0.001). There were no significant differences between the two HR-FPCT protocols (p = 0.25). The remaining Acc-FPCT protocols were rated significantly inferior to HR-MSCT. The inter-rater reliability was excellent (ICC (2,k) = 0.925; CI [0.92-0.93]). The dose length product was significantly lower in all Acc-FPCT protocols compared to HR-MSCT.

CONCLUSION

The results of our cadaver-based study highlight the utility of certain Acc-FPCT protocols as a viable alternative to HR-MSCT in preoperative temporal bone imaging, improving the visualization of critical anatomical landmarks without increasing radiation exposure.

Image Quality Evaluation for Brain Soft Tissue in Neuroendovascular Treatment by Dose-Reduction Mode of Dual-Axis "Butterfly" Scan

BACKGROUND AND PURPOSE

Flat panel conebeam CT (CBCT) is essential for detecting hemorrhagic complications during neuroendovascular treatments. Despite its superior image quality and trajectory over conventional CBCT (circular scan), the dual-axis butterfly scan has a slightly higher radiation dose relative to conventional CBCT. This study evaluates the image quality in dose-reduction mode to uncover the appropriate radiation dose for the butterfly scan.

MATERIALS AND METHODS

We prospectively included patients who were scheduled for neuroendovascular treatment and underwent conventional CBCT and the dose-reduction mode of the butterfly scan. Two reduced radiation dose modes were used for the butterfly scan: medium-dose butterfly scan (70% of the original dose, 45 mGy) or low-dose butterfly scan (50% of the original dose, 30 mGy). The enrolled patients were assigned alternately to undergo either the medium- or low-dose butterfly scan. We evaluated and compared artifacts, contrast, and discrimination of the corticomedullary junction between conventional CBCT and one of the dose-reduction modes of the butterfly scan, with a 5-point scale scoring system.

RESULTS

Twenty patients were enrolled in each of the medium- and low-dose groups, totaling 40 patients. Compared with conventional CBCT, the medium-dose butterfly group exhibited reduced artifacts, enhanced contrast, and corticomedullary junction discrimination (except in the occipital lobe). While the low-dose butterfly group exhibited markedly reduced artifacts and improved contrast (except in the occipital lobe), a significant improvement in corticomedullary junction discrimination was not observed.

CONCLUSIONS

Even with dose reduction, the specialized trajectory of the butterfly scan enables artifact reduction, contrast improvement, and enhanced corticomedullary junction discrimination. However, the impact of the reduced dose was more noticeable, particularly in the occipital region where susceptibility to bone interference resulted in decreased contrast and compromised corticomedullary junction discrimination.

Hybrid CT Angio Suite for Acute Ischemic Stroke: A New Time-Saving Workflow Model?

Objectives: Explore the effect of the introduction of a hybrid CT angio suite on the in-hospital workflow time of patients with acute ischemic stroke. Methods: This was a retrospective observational case-control study. All consecutive patients admitted to our emergency department with suspected ischemic stroke who underwent stroke imaging and mechanical thrombectomy (MT) in the new hybrid CT angio suite from October 2023 to March 2024 were included in the study. The primary outcome was the evaluation of in-hospital workflow times by the assessment of both the time from hospital admission to the beginning of the endovascular treatment (door-to-groin time, DTG) and the time from the interpretation of imaging to arterial puncture (CT-to-groin time, CTTG). The secondary aim was the evaluation of the clinical outcome through the evaluation of the mRS at 3 months. These data were compared to the control group. Results: Between October 2023 and March 2024, 50 consecutive patients with suspected ischemic stroke underwent neuroimaging and MT in the hybrid CT angio suite. We observed a significant reduction of the median DTG time from 71 min to 36 min (p < 0.001) and the median CT-to-groin time from 44 min to 12 min (p < 0.001) compared to the control group. Conclusions: The introduction of the hybrid CT angio suite dedicated to acute ischemic stroke has definitely reduced in-hospital delays, allowing better management of these patients.

DOT sign indicates persistent hypoperfusion and poor outcome in patients with incomplete reperfusion following thrombectomy

BACKGROUND

Distal occlusions associated with incomplete reperfusion (expanded Thrombolysis in Cerebral Infarction,

METHODS

Retrospective registry analysis of patients undergoing endovascular therapy between July 2020 and December 2022, with available immediate post-interventional FPDCT and 24 hours follow-up perfusion imaging. Persistent hypoperfusion was defined as a perfusion deficit at 24 hours directly corresponding to the area of incomplete reperfusion on final angiography run. The DOT sign was defined as a punctiform or tubular hyperdense signal increase on FPDCT indicative of a residual occlusion. Association between the DOT sign (present/absent) with the occurrence of persistent hypoperfusion and poor outcome (modified Rankin scale (mRS) score 3-6) was evaluated using logistic regression analysis.

RESULTS

Of 292 patients included (median age 73 years; 47% female), 209 had incomplete reperfusion. Among patients with incomplete reperfusion, 61% had a present DOT sign and 46% had persistent hypoperfusion. In the overall cohort, but also within each eTICI stratum, a present DOT sign was associated with persistent hypoperfusion on 24±12 hours follow-up perfusion imaging (adjusted odds ratio (aOR) 4.8, 95% confidence interval (CI) 2.0 to 12.3 for patients with eTICI 2 a-2c). A present DOT sign was also associated with poor outcome (aOR 2.6, 95% CI 1.1 to 6.2).

CONCLUSION

Patients with Collapse

Key Words

• CT Angiography
• Intervention
• MR perfusion
• Stroke
• Thrombectomy

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Affiliation(s)

Adnan Mujanovic Department of Diagnostic and Interventional Neuroradiology, University Hospital Bern Inselspital, Bern, Switzerland Graduate School for Health Sciences, University of Bern, Bern, Switzerland
Daniel Windecker Department of Diagnostic and Interventional Neuroradiology, University Hospital Bern Inselspital, Bern, Switzerland
Bettina Serrallach Department of Diagnostic and Interventional Neuroradiology, University Hospital Bern Inselspital, Bern, Switzerland
Christoph C Kurmann Department of Diagnostic and Interventional Neuroradiology, University Hospital Bern Inselspital, Bern, Switzerland Graduate School for Health Sciences, University of Bern, Bern, Switzerland Department of Diagnostic, Interventional and Pediatric Radiology, University Hospital Bern Inselspital, Bern, Switzerland
Roman Rohner Department of Diagnostic and Interventional Neuroradiology, University Hospital Bern Inselspital, Bern, Switzerland Graduate School for Health Sciences, University of Bern, Bern, Switzerland
Elias Auer Department of Neurology, Inselspital University Hospital Bern, Bern, Switzerland
Petra Cimflova Department of Diagnostic and Interventional Neuroradiology, University Hospital Bern Inselspital, Bern, Switzerland Department of Neuroradiology, University Hospital Freiburg, Freiburg, Germany Department of Medical Imaging, St. Anne's University Hospital Brno, Brno, Czech Republic
Thomas R Meinel Department of Neurology, Inselspital University Hospital Bern, Bern, Switzerland
Franziska Dorn Department of Neuroradiology, University Hospital Bonn, Bonn, Germany
René Chapot Department of Neuroradiology and Endovascular Therapy, Alfried Krupp Krankenhaus Ruttenscheid, Essen, Germany
David Seiffge Department of Neurology, Inselspital University Hospital Bern, Bern, Switzerland
Eike Immo I Piechowiak Department of Diagnostic and Interventional Neuroradiology, University Hospital Bern Inselspital, Bern, Switzerland
Tomas Dobrocky Department of Diagnostic and Interventional Neuroradiology, University Hospital Bern Inselspital, Bern, Switzerland
Jan Gralla Department of Diagnostic and Interventional Neuroradiology, University Hospital Bern Inselspital, Bern, Switzerland
Urs Fischer Department of Neurology, Inselspital University Hospital Bern, Bern, Switzerland
Sara Pilgram-Pastor Department of Diagnostic and Interventional Neuroradiology, University Hospital Bern Inselspital, Bern, Switzerland
Johannes Kaesmacher Department of Diagnostic and Interventional Neuroradiology, University Hospital Bern Inselspital, Bern, Switzerland Diagnostic and Interventional Neuroradiology, CIC-IT 1415, CHRU de Tours, Tours, France Le Studium Loire Valley Institute for Advanced Studies, Orléans, France

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Connecting the DOTs: a novel imaging sign on flat-panel detector CT indicating distal vessel occlusions after thrombectomy

BACKGROUND

Immediate non-contrast post-interventional flat-panel detector CT (FPDCT) has been suggested as an imaging tool to assess complications after endovascular therapy (EVT). We systematically investigated a new imaging finding of focal hyperdensities correlating with remaining distal vessel occlusion after EVT.

METHODS

A single-center retrospective analysis was conducted for all acute ischemic stroke patients admitted between July 2020 and December 2022 who underwent EVT and immediate post-interventional FPDCT. A blinded core lab performed reperfusion grading on post-interventional digital subtraction angiography (DSA) images and evaluated focal hyperdensities on FPDCT (here called the distal occlusion tracker (DOT) sign). DOT sign was defined as a tubular or punctiform, vessel confined, hyperdense signal within the initial occlusion target territory. We assessed sensitivity and specificity of the DOT sign when compared with DSA findings.

RESULTS

The median age of the cohort (n=215) was 74 years (IQR 63-82) and 58.6% were male. The DOT sign was positive in half of the cohort (51%, 110/215). The DOT sign had high specificity (85%, 95% CI 72% to 93%), but only moderate sensitivity (63%, 95% CI 55% to 70%) for detection of residual vessel occlusions. In comparison to the core lab, operators overestimated complete reperfusion in a quarter of the entire cohort (25%, 53/215). In more than half of these cases (53%, 28/53) there was a positive DOT sign, which could have mitigated this overestimation.

CONCLUSION

The DOT sign appears to be a frequent finding on immediate post-interventional FPDCT. It correlates strongly with incomplete reperfusion and indicates residual distal vessel occlusions. In the future, it may be used to complement grading of reperfusion success and may help mitigating overestimation of reperfusion in the acute setting.

Stroke Evaluation in the Interventional Suite Using Dual-Layer Detector Cone-Beam CT: a First-in-human Prospective Cohort Study (the Next Generation X-ray Imaging System Trial)

PURPOSE

Cone-beam CT in the interventional suite could be an alternative to CT to shorten door-to-thrombectomy time. However, image quality in cone-beam CT is limited by artifacts and poor differentiation between gray and white matter. This study compared non-contrast brain dual-layer cone-beam CT in the interventional suite to reference standard CT in stroke patients.

METHODS

A prospective single-center study enrolled consecutive participants with ischemic or hemorrhagic stroke. The hemorrhage detection accuracy, per-region ASPECTS accuracy and subjective image quality (Likert scales for gray-white matter differentiation, structure perception and artifacts) were assessed by three neuroradiologists blinded to clinical data on dual-layer cone-beam CT 75 keV monoenergetic images compared to CT. Objective image quality was assessed by region-of-interest metrics. Non-inferiority for hemorrhage detection and ASPECTS accuracy was determined by the exact binomial test with a one-sided lower performance boundary prospectively set to 80% (98.75% CI).

RESULTS

27 participants were included (74 years ± 9; 19 female) in the hyperacute or acute stroke phase. One reader missed a small bleeding, but all hemorrhages were detected in the majority analysis (100% accuracy, CI lower boundary 86%, p = 0.002). ASPECTS majority analysis showed 90% accuracy (CI lower boundary 85%, p < 0.001). Sensitivity was 66% (individual readers 67%, 69%, and 76%), specificity was 97% (97%, 96%, 89%). Subjective and objective image quality were inferior to CT.

CONCLUSION

In a small single-center cohort, dual-layer cone-beam CT showed non-inferior hemorrhage detection and ASPECTS accuracy to CT. Despite inferior image quality, the technique may be useful for stroke evaluation in the interventional suite.

TRIAL REGISTRATION NUMBER

NCT04571099 (clinicaltrials.gov). Prospectively registered 2020-09-04.

Incidence, Risk Factors, and Clinical Implications of Subarachnoid Hyperdensities on Flat-Panel Detector CT following Mechanical Thrombectomy in Patients with Anterior Circulation Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Flat-panel detector CT immediately after mechanical thrombectomy can detect complications, including early hemorrhagic transformation and subarachnoid hyperdensities. The clinical significance of subarachnoid hyperdensities in patients undergoing mechanical thrombectomy remains unclear.

MATERIALS AND METHODS

We studied 223 patients who underwent mechanical thrombectomy for anterior circulation stroke who had flat-panel detector CT performed immediately after the procedure and had follow-up imaging within 24 hours. Subarachnoid hyperdensity severity was categorized into 5 grades (subarachnoid hyperdensities, 0: absent to subarachnoid hyperdensities, IV: extensive). Baseline and procedural characteristics as well as outcome measures were analyzed using group comparisons and multivariable logistic regression analyses.

RESULTS

Overall, 100/223 (45%) patients showed subarachnoid hyperdensities on immediate postinterventional flat-panel detector CT. The factors associated with an increased subarachnoid hyperdensity risk were the following: medium-vessel occlusion or distal-vessel occlusion compared with a large-vessel occlusion, a more distal device position, a higher number of device passes, a larger volume of contrast applied, worse final reperfusion expanded TICI, and after receiving IV thrombolysis. The occurrence of subarachnoid hyperdensity grades II-IV was independently associated with worse functional outcomes (adjusted OR for mRS, 3-6: 2.2; 95% CI 1.1-4.3), whereas patients with subarachnoid hyperdensity grade I had outcomes similar to those in patients without subarachnoid hyperdensities.

CONCLUSIONS

Our study identified risk factors for subarachnoid hyperdensities, most of which reflect increasingly challenging procedures or more peripheral recanalization attempts. The presence of subarachnoid hyperdensity grades II-IV was associated with poorer outcomes, suggesting the need for personalized strategies to reduce its incidence and severity or potentially improve recovery after subarachnoid hyperdensities.

Flat-panel Detector Perfusion Imaging and Conventional Multidetector Perfusion Imaging in Patients with Acute Ischemic Stroke : A Comparative Study

PURPOSE

Flat-panel detector computed tomography (FDCT) is increasingly used in (neuro)interventional angiography suites. This study aimed to compare FDCT perfusion (FDCTP) with conventional multidetector computed tomography perfusion (MDCTP) in patients with acute ischemic stroke.

METHODS

In this study, 19 patients with large vessel occlusion in the anterior circulation who had undergone mechanical thrombectomy, baseline MDCTP and pre-interventional FDCTP were included. Hypoperfused tissue volumes were manually segmented on time to maximum (Tmax) and time to peak (TTP) maps based on the maximum visible extent. Absolute and relative thresholds were applied to the maximum visible extent on Tmax and relative cerebral blood flow (rCBF) maps to delineate penumbra volumes and volumes with a high likelihood of irreversible infarcted tissue ("core"). Standard comparative metrics were used to evaluate the performance of FDCTP.

RESULTS

Strong correlations and robust agreement were found between manually segmented volumes on MDCTP and FDCTP Tmax maps (r = 0.85, 95% CI 0.65-0.94, p < 0.001; ICC = 0.85, 95% CI 0.69-0.94) and TTP maps (r = 0.91, 95% CI 0.78-0.97, p < 0.001; ICC = 0.90, 95% CI 0.78-0.96); however, direct quantitative comparisons using thresholding showed lower correlations and weaker agreement (MDCTP versus FDCTP Tmax 6 s: r = 0.35, 95% CI -0.13-0.69, p = 0.15; ICC = 0.32, 95% CI 0.07-0.75). Normalization techniques improved results for Tmax maps (r = 0.78, 95% CI 0.50-0.91, p < 0.001; ICC = 0.77, 95% CI 0.55-0.91). Bland-Altman analyses indicated a slight systematic underestimation of FDCTP Tmax maximum visible extent volumes and slight overestimation of FDCTP TTP maximum visible extent volumes compared to MDCTP.

CONCLUSION

FDCTP and MDCTP provide qualitatively comparable volumetric results on Tmax and TTP maps; however, direct quantitative measurements of infarct core and hypoperfused tissue volumes showed lower correlations and agreement.

Sine Spin flat detector CT can improve cerebral soft tissue imaging: a retrospective in vivo study

BACKGROUND

Flat detector computed tomography (FDCT) is frequently applied for periinterventional brain imaging within the angiography suite. Novel technical developments such as the Sine Spin FDCT (S-FDCT) may provide an improved cerebral soft tissue contrast. This study investigates the effect of S-FDCT on the differentiation between gray and white matter compared to conventional FDCT (C-FDCT) and multidetector computed tomography (MDCT).

METHODS

A retrospective analysis of a prospectively maintained patient database was performed, including patients who underwent mechanical thrombectomy in our institution and received S-FDCT or C-FDCT as well as MDCT. Differentiation between gray and white matter on the contralateral hemisphere to the ischemic stroke was analyzed quantitatively by contrast-to-noise ratio (CNR) and qualitatively (5-point ordinal scale).

RESULTS

In a cohort of 109 patients, MDCT demonstrated the best differentiation between gray and white matter compared to both FDCT techniques (p ≤ 0.001). Comparing both generations of FDCT, S-FDCT provided better visibility of the basal ganglia (p = 0.045) and the supratentorial cortex (p = 0.044) compared to C-FDCT both in quantitative and qualitative analyses. Median CNR were as follows: S-FDCT 2.41 (interquartile range [IQR] 1.66-3.21), C-FDCT 0.96 (0.46-1.70), MDCT 3.43 (2.83-4.17). For basal ganglia, median score and IQR were as follows: S-FDCT 2.00 (2.00-3.00), C-FDCT 1.50 (1.00-2.00), MDCT 5.00 (4.00-5.00).

CONCLUSIONS

The novel S-FDCT improves the periinterventional imaging quality of cerebral soft tissue compared to C-FDCT. Thus, it may improve the diagnosis of complications within the angiography suite. MDCT provides the best option for x-ray-based imaging of the brain tissue.

RELEVANCE STATEMENT

Flat detector computed tomography is a promising technique for cerebral soft tissue imaging, while the novel Sine Spin flat detector computed tomography technique improves imaging quality compared to conventional flat detector computed tomography and thus may facilitate periinterventional diagnosis of gray and white matter.

KEY POINTS

• Flat detector computed tomography (FDCT) is frequently applied for periinterventional brain imaging. • The potential of novel Sine Spin FDCT (S-FDCT) is unknown so far. • S-FDCT improves the visibility of cerebral soft tissue compared to conventional FDCT. • Multidetector computed tomography is superior to both FDCT techniques. • S-FDCT may facilitate the evaluation of brain parenchyma within the angiography suite.

Priorities for Advancements in Neuroimaging in the Diagnostic Workup of Acute Stroke

STAIR XII (12th Stroke Treatment Academy Industry Roundtable) included a workshop to discuss the priorities for advancements in neuroimaging in the diagnostic workup of acute ischemic stroke. The workshop brought together representatives from academia, industry, and government. The participants identified 10 critical areas of priority for the advancement of acute stroke imaging. These include enhancing imaging capabilities at primary and comprehensive stroke centers, refining the analysis and characterization of clots, establishing imaging criteria that can predict the response to reperfusion, optimizing the Thrombolysis in Cerebral Infarction scale, predicting first-pass reperfusion outcomes, improving imaging techniques post-reperfusion therapy, detecting early ischemia on noncontrast computed tomography, enhancing cone beam computed tomography, advancing mobile stroke units, and leveraging high-resolution vessel wall imaging to gain deeper insights into pathology. Imaging in acute ischemic stroke treatment has advanced significantly, but important challenges remain that need to be addressed. A combined effort from academic investigators, industry, and regulators is needed to improve imaging technologies and, ultimately, patient outcomes.

Current and future trends in acute ischemic stroke treatment: direct-to-angiography suite, middle vessel occlusion, large core, and minor strokes

Since the publication of the landmark thrombectomy trials in 2015, the field of endovascular therapy for ischemic stroke has been rapidly growing. The very low number needed to treat to provide functional benefits shown by the initial randomized trials has led clinicians and investigators to seek to translate the benefits of endovascular therapy to other patient subgroups. Even if the treatment effect is diminished, currently available data has provided sufficient information to extend endovascular therapy to large infarct core patients. Recently, published data have also shown that sophisticated imaging is not necessary for late time- window patients. As a result, further research into patient selection and the stroke pathway now focuses on dramatically reducing door-to-groin times and improving outcomes by circumventing classical imaging paradigms altogether and employing a direct-to-angio suite approach for selected large vessel occlusion patients in the early time window. While the results of this approach mainly concern patients with severe deficits, there are further struggles to provide evidence of the efficacy and safety of endovascular treatment in minor stroke and large vessel occlusion, as well as in patients with middle vessel occlusions. The current lack of good quality data regarding these patients provides significant challenges for accurately selecting potential candidates for endovascular treatment. However, current and future randomized trials will probably elucidate the efficacy of endovascular treatment in these patient populations.

Effective Dose Measurements of the Latest-Generation Angiographic System in Patients with Acute Stroke: A Comparison with the Newest Multidetector CT Generation

BACKGROUND AND PURPOSE

Patients with acute ischemic stroke are increasingly triaged with one-stop management approaches, resulting in baseline imaging with a flat detector CT scanner. This study aimed to estimate the effective dose to a patient of a novel cervical and intracranial flat detector CT angiography and a flat detector CT perfusion protocol and to compare it with the effective dose of analogous multidetector row CT protocols.

MATERIALS AND METHODS

We estimated the effective dose to the patient according to the International Commission on Radiological Protection 103 using an anthropomorphic phantom with metal oxide semiconductor field effect transistor dosimeters. Placement was according to the organ map provided by the phantom manufacturer. We used 100 measurement points within the phantom, and 18 metal oxide semiconductor field effect transistor dosimeters were placed on the surface of the phantom. All protocols followed the manufacturer's specifications, and patient positioning and collimation were performed as in routine clinical practice. Measurements were obtained on the latest-generation angiography and multidetector row CT systems with identical placement of the metal oxide semiconductor field effect transistor dosimeters.

RESULTS

The estimated effective doses of the investigated perfusion protocols were 4.52 mSv (flat detector CT perfusion without collimation), 2.88 mSv (flat detector CT perfusion with collimation), and 2.17 mSv (multidetector row CT perfusion). A novel protocol called portrait flat detector CT angiography that has a z-axis coverage area comparable with that of multidetector row CT angiography had an estimated effective dose of 0.91 mSv, while the dose from multidetector row CT was 1.35 mSv.

CONCLUSIONS

The estimated effective dose to the patient for flat detector CT perfusion and angiography on a modern biplane angiography system does not deviate substantially from that of analogous multidetector row CT protocols.

Principles, techniques and applications of high resolution cone beam CT angiography in the neuroangio suite

The aim of this review is to describe the acquisition and reformatting of state of the art high resolution cone beam CT (HR-CBCT) and demonstrate its role in multiple neurovascular conditions as a tool to improve the understanding of disease and guide therapeutic decisions. First, we will review the basic principle of CBCT acquisition, followed by the injection protocols and the reformatting paradigms. Next, multiple applications in different pathological conditions such as aneurysms, arteriovenous malformations, dural arteriovenous fistulas, and stroke will be described. HR-CBCT angiography, widely available, is uniquely useful in certain clinical scenarios to improve the understanding of disease and guide therapeutic decisions. It rapidly is becoming an essential tool for the contemporary neurointerventionalist.AChoAho.