Intracranial CT Angiography Research Articles

A Case Report of Pituitary Apoplexy and Acute Ischemic Stroke (P2-5.004)

<h3>Objective:</h3> N/A <h3>Background:</h3> Pituitary apoplexy is a medical emergency resulting from acute hemorrhage or infarction of the pituitary gland. Symptoms include headache, diplopia, visual impairment, and encephalopathy. We present a diagnostically challenging case of pituitary apoplexy in a patient who presented with fever, headache, diplopia, cerebrospinal fluid showing neutrophilic pleocytosis with elevated protein, and neuroimaging showing a left basal ganglia infarct with diffuse cerebral vasospasm. <h3>Design/Methods:</h3> A 46 year old post-menopausal female exhibiting a two day prodrome of severe headaches, nausea, and double vision. She presented to the emergency department febrile (104.6 F), disoriented, with a left lateral rectus palsy and mild right hemiparesis. MRI brain revealed an enhancing suprasellar lesion extending into the sphenoid sinuses and left cavernous sinus with optic chiasm effacement. Diffusion weighted imaging showed evidence of a left recurrent artery of Heubner infarct. Intracranial CT angiography revealed anterior circulation vasospasm. Cerebrospinal fluid resulted in 300 nucleated cells with neutrophilic predominance and elevated protein (121 mg/dL). Her presentation and workup was concerning for an intracranial abscess versus pituitary apoplexy. The patient underwent transsphenoidal pituitary resection, confirming a macroadenoma and pituitary apoplexy. As her CSF infectious work up and biopsy cultures remained negative, the results were suggestive of sterile inflammation and her antibiotics were discontinued. Following surgical intervention and on six month follow up, the patient remained at her baseline functional status without deficits. <h3>Results:</h3> N/A <h3>Conclusions:</h3> Pituitary macroadenomas have varying severity of presentations. Pituitary apoplexy should be considered in a patient with altered sensorium, severe headache, and cranial nerve deficits. Cerebral infarcts can result from mechanical compression from mass effect or arterial vasospasm secondary to vasoactive substances released from necrotic and hemorrhagic pituitary tumor. Prompt diagnosis and early intervention can reduce mortality and morbidity and is critical for successful patient outcomes. <b>Disclosure:</b> Dr. Sandhu has nothing to disclose. Dr. Saini has nothing to disclose. Dr. Liang has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Abbvie.

Time-of-Flight Intracranial MRA at 3 T versus 5 T versus 7 T: Visualization of Distal Small Cerebral Arteries.

Background Three-dimensional (3D) time-of-flight (TOF) MR angiography (MRA) at 7 T has been reported to have high image quality for visualizing small perforating vessels. However, B1 inhomogeneity and more physiologic considerations limit its applications. Angiography at 5 T may provide another choice for intracranial vascular imaging. Purpose To evaluate the image quality and cerebrovascular visualization of 5-T 3D TOF MRA for visualizing intracranial small branch arteries. Materials and Methods Participants (healthy volunteers or participants with a history of ischemic stroke undergoing intracranial CT angiography or MRA for identifying steno-occlusive disease) were prospectively included from September 2021 to November 2021. Each participant underwent 3-T, 5-T, and 7-T 3D TOF MRA with use of customized MR protocols within 48 hours. Radiologist scoring from 0 (invisible) to 3 (excellent) and quantitative assessment were obtained to evaluate the image quality. The Friedman test was used for comparison of characteristics derived from 3 T, 5 T, and 7 T. Results A total of 12 participants (mean age ± SD, 38 years ± 9; nine men) were included. Visualizations of the distal arteries and small vessels at 5-T TOF MRA were significantly higher than those at 3 T (median score: 3.0 vs 2.0, all P < .001 for distal segments and lenticulostriate artery; median score: 2.0 vs 0, P < .001 for pontine artery). The total length of small vessel branches detected at 5 T was larger than that at 3 T (5.1 m ± 0.7 vs 1.9 m ± 0.4; P < .001). However, there was no evidence of a significant difference compared with 7 T in either the depiction of distal segments and small vessel branches (average median score, 2.5; all P > .05) or the quantitative measurements (total length, 5.6 m ± 0.5; P = .41). Conclusion Three-dimensional time-of-flight MR angiography at 5 T presented the capability to provide superior visualization of distal large arteries and small vessel branches (in terms of subjective and quantitative assessment) to 3 T and had image quality similar to 7 T. © RSNA, 2022 Online supplemental material is available for this article. An earlier incorrect version appeared online. This article was corrected on September 14, 2022.

Diagnostic yield of 90-kVp low-tube-voltage carotid and intracerebral CT-angiography: effects on radiation dose, image quality and diagnostic performance for the detection of carotid stenosis.

To investigate the impact of low-tube-voltage 90-kVp acquisition combined with advanced modeled iterative reconstruction algorithm (Admire) on radiation exposure, image quality, artifacts, and assessment of stenosis in carotid and intracranial CTangiography (CTA). Dual-energy CTA studies of 43 patients performed on a third-generation 192-slice dual-source CT were retrospectively evaluated. Intraindividual comparison of 90-kVp and linearlyblended 120-kVp equivalent image series (M_0.6, 60% 90-kVp, 40% Sn-150-kVp) was performed. Contrast-to-noise and signal-to-noise ratios of common carotid artery, internal carotid artery, middle cerebral artery, and basilar artery were calculated. Qualitative image analysis included evaluation of artifacts and suitability for angiographical assessment at shoulder level, carotid bifurcation, siphon, and intracranial by three independent radiologists. Detection and quantification of carotid stenosis were performed. Radiation dose was expressed as dose-lengthproduct (DLP). Contrast-to-noise values of all arteries were significantly increased in 90-kVp compared to M_0.6 (p < 0.001). Suitability for angiographical evaluation was rated excellent with low artifacts for all levels in both image series. Both 90-kVp and M_0.6 showed excellent accordance for detection and grading of carotid stenosis with almost perfect interobserver agreement (carotid stenoses in 32 of 129 segments; intraclass correlation coefficient, 0.94). dose-lengthproduct was reduced by 40.3% in 90-kVp (110.6 ± 32.1 vs 185.4 ± 47.5 mGy·cm, p < 0.001). 90-kVp carotid and intracranial CTA with Admire provides increased quantitative and similarly good qualitative image quality, while reducing radiation exposure substantially compared to M_0.6. Diagnostic performance for arterial stenosis detection and quantification remained excellent. Advances in knowledge: 90-kVp carotid and intracranial CTA with an advanced iterative reconstruction algorithm results in excellent image quality and reduction of radiation exposure without limiting diagnostic performance.

Photon-Counting Computed Tomography for Vascular Imaging of the Head and Neck: First In Vivo Human Results.

The purpose of this study was to evaluate image quality of a spectral photon-counting detector (PCD) computed tomography (CT) system for evaluation of major arteries of the head and neck compared with conventional single-energy CT scans using energy-integrating detectors (EIDs). In this institutional review board-approved study, 16 asymptomatic subjects (7 men) provided informed consent and received both PCD and EID contrast-enhanced CT scans of the head and neck (mean age, 58 years; range, 46-75 years). Tube settings were (EID: 120 kVp/160 mA vs PCD: 140 kVp/108 mA) for all volunteers. Quantitative analysis included measurements of mean attenuation, image noise, and contrast-to-noise ratio (CNR). Spectral PCD data were used to reconstruct virtual monoenergetic images and iodine maps. A head phantom was used to validate iodine concentration measurements in PCD images only. Two radiologists blinded to detector type independently scored the image quality of different segments of the arteries, as well as diagnostic acceptability, image noise, and severity of artifacts of the PCD and EID images. Reproducibility was assessed with intraclass correlation coefficient. Linear mixed models that account for within-subject correlation of analyzed arterial segments were used. Linear regression and Bland-Altman analysis with 95% limits of agreement were used to calculate the accuracy of material decomposition. Photon-counting detector image quality scores were significantly higher compared with EID image quality scores with lower image noise (P < 0.01) and less image artifacts (P < 0.001). Photon-counting detector image noise was 9.1% lower than EID image noise (8.0 ± 1.3 HU vs 8.8 ± 1.5 HU, respectively, P < 0.001). Arterial segments showed artifacts on EID images due to beam hardening that were not present on PCD images. On PCD images of the head phantom, there was excellent correlation (R = 0.998) between actual and calculated iodine concentrations without significant bias (bias: -0.4 mg/mL [95% limits of agreements: -1.1 to 0.4 mg/mL]). Iodine maps had 20.7% higher CNR compared with nonspectral PCD (65.2 ± 9.0 vs 54.0 ± 4.5, P = 0.01), and virtual monoenergetic image at 70 keV showed similar CNR to nonspectral images (52.6 ± 4.2 vs 54.0 ± 4.5, P = 0.39). Photon-counting CT has the potential to improve the image quality of carotid and intracranial CT angiography compared with single-energy EID CT.

Increased image quality and reduced radiation dose and contrast media volume: a holistic approach to intracranial CTA

To investigate the dose-length product (DLP) during intracranial computed tomography angiography (CTA) using a patient-specific contrast formula. Intracranial CTA was performed on 120 patients using 64-channel CT. Patients were subjected in equal numbers to one of two acquisitions/contrast medium protocols. Protocol A, consisted of 80ml contrast medium and protocol B, involved a novel contrast medium formula. In each protocol, contrast medium and saline were injected at a flow rate of 4.5ml/s. The DLP and contrast volume (CV) were measured between each protocol and the data obtained were compared using two-tailed independent t-test. Mean arterial vessel attenuation was up to 56% (p<0.01) higher using protocol B compared with A. In the venous system, the mean vessel attenuation was significantly lower in protocol B than A with a maximum reduction of 93% (p<0.001). The mean CV was significantly lower in protocol B (53±10ml) compared to A (80±1ml, p<0.001). The scan time was equal in each protocol (B, 4.22±1.2seconds; A, 4.01±1.3seconds). A significant reduction in mean DLP was demonstrated in protocol B (3.99±0.22mSv) compared to A (4.74±0.22mSv; p=0.02). A significant reduction in CV and DLP during intracranial CTA can be achieved when employing a patient-specific contrast medium formula.

Reinitiation of Withdrawn or Modified Neuroimaging Requests After Collaborative Consultation

This study explored four common sequences of interaction between providers and a collaborative, nondenial model preauthorization program to assess the extent to which the collaborative consultation impacted care delivered to a patient in the 30 days after a neuroimaging consult. In each of the sequences examined, providers interacted with the preauthorization program's consulting radiologist and modified their imaging study requests during the interaction. If providers did not subsequently reinitiate the original study requests, then it suggests that the study resulting from the collaborative consultation fulfilled the providers' clinical objective. Four years of retrospective authorization and clinical data were analyzed to determine the rate at which requests modified through peer-to-peer consultation were reinitiated in the following four sequences: 1) request for head computed tomography (CT) modified to head magnetic resonance imaging (MRI), 2) request for both head CT and intracranial CT angiography (CTA) or both head MRI and intracranial MRA modified to a request for a single study, 3) request for both a CT of the head and sinuses modified to a request for a single study, and 4) request for an MRI of the head and orbits modified to a request for a single study. In three of the sequences, no provider reinitiated a study within 30 days. In the fourth sequence, only 4 of 64 (6%) withdrawn requests for head CT/MRI or head CTA/MRA were reinitiated within 30 days. Modifications after collaborative consultations rarely lead to repeat imaging requests, confirming the utility of the consultations.

Preliminary clinical application of an adaptive iterative statistical reconstruction algorithm inhead and neck computed tomography angiography with low tube voltage and a low concentration of contrast medium

Abstract Objective To evaluate the feasibility of using a low concentration of contrast medium (Visipaque 270 mgI/mL), low tube voltage, and an advanced image reconstruction algorithm in head and neck computed tomography angiography (CTA). Methods Forty patients (22 men and 18 women; average age 48.7 ± 14.25 years; average body mass index 23.9 ± 3.7 kg/m2) undergoing CTA for suspected vascular diseases were randomly assigned into two groups. Group A (n = 20) was administered 370 mgI/mL contrast medium, and group B (n = 20) was administered 270 mgI/mL contrast medium. Both groups were administered at a rate of 4.8 mL/s and an injection volume of 0.8 mL/kg. Images of group A were obtained with 120 kVp and filtered back projection (FBP) reconstruction, whereas images of group B were obtained with 80 kVp and 80% adaptive iterative statistical reconstruction algorithm (ASiR). The CT values and standard deviations of intracranial arteries and image noise on the corona radiata were measured to calculate the contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR). The beam-hardening artifacts (BHAs) around the skull base were calculated. Two readers evaluated the image quality with volume rendered images using scores from 1 to 5. The values between the two groups were statistically compared. Results The mean CT value of the intracranial arteries in group B was significantly higher than that in group A (P &lt; 0.001). The CNR and SNR values in group B were also statistically higher than those in group A (P &lt; 0.001). Image noise and BHAs were not significantly different between the two groups. The image quality score of VR images of in group B was significantly higher than that in group A (P = 0.001). However, the quality scores of axial enhancement images in group B became significantly smaller than those in group A (P&lt; 0.001). The CT dose index volume and dose-length product were decreased by 63.8% and 64%, respectively, in group B (P &lt; 0.001 for both). Conclusion Visipaque combined with 80 kVp and 80% ASiR provided similar image quality in intracranial CTA with 64% radiation dose reduction compared with the use of Iopamidol, 120 kVp, and FBP reconstruction.

Adaptive statistical iterative reconstruction reduces patient radiation dose in neuroradiology CT studies

Adaptive statistical iterative reconstruction (ASIR) can decrease image noise, thereby generating CT images of comparable diagnostic quality with less radiation. The purpose of this study is to quantify the effect of systematic use of ASIR versus filtered back projection (FBP) for neuroradiology CT protocols on patients' radiation dose and image quality. We evaluated the effect of ASIR on six types of neuroradiologic CT studies: adult and pediatric unenhanced head CT, adult cervical spine CT, adult cervical and intracranial CT angiography, adult soft tissue neck CT with contrast, and adult lumbar spine CT. For each type of CT study, two groups of 100 consecutive studies were retrospectively reviewed: 100 studies performed with FBP and 100 studies performed with ASIR/FBP blending factor of 40 %/60 % with appropriate noise indices. The weighted volume CT dose index (CTDIvol), dose-length product (DLP) and noise were recorded. Each study was also reviewed for image quality by two reviewers. Continuous and categorical variables were compared by t test and free permutation test, respectively. For adult unenhanced brain CT, CT cervical myelography, cervical and intracranial CT angiography and lumbar spine CT both CTDIvol and DLP were lowered by up to 10.9 % (p < 0.001), 17.9 % (p = 0.005), 20.9 % (p < 0.001), and 21.7 % (p = 0.001), respectively, by using ASIR compared with FBP alone. Image quality and noise were similar for both FBP and ASIR. We recommend routine use of iterative reconstruction for neuroradiology CT examinations because this approach affords a significant dose reduction while preserving image quality.

Effect of region-of-interest placement in bolus tracking cerebral computed tomography angiography

Premature or delayed triggering of semiautomatic contrast tracking during intracranial computed tomographic angiography can occur due to artifact from dense contrast in the superior vena cava or brachiocephalic veins near the anterior aortic arch. We determine if placement of bolus tracking region-of-interest in the posterior thoracic aorta can prevent suboptimal intracranial arterial opacification. Intracranial computed tomography angiographies from 80 patients performed on the same scanner were retrospectively evaluated. Thirty-seven consecutive patients with bolus tracking region-of-interest (ROI) placed in the anterior thoracic aorta (group A) and 43 consecutive patients with ROI placed in the posterior thoracic arch (group B) were identified. Two neuroradiologists scored the quality of intracranial computed tomography angiography on a four-point scale. Quantitative measurement of intracranial arterial opacification was also performed. The proportions of patients with poorest quality score as well as the proportions of the patients with the worst degree of intracranial arterial opacification (<10th percentile) were compared between groups A and B using two-sample proportion test. Qualitative evaluation of the intracranial computed tomography angiography showed 4 (11%) patients in group A with poor quality (score of 1), while all patients in group B scored 2 or higher (p = 0.028). Seven (19%) patients in group A had the lowest quantitative score (mean arterial opacification < 10th percentile) while 1 (2.5%) patient in group B had the lowest score (p = 0.018). Bolus tracking in the posterior thoracic aorta reduces the chance of suboptimal intracranial computed tomography angiography.

Abstract WP54: Defining Acute Ischemic Stroke Tissue Pathophysiology Using Whole Brain 320 Slice Ct Perfusion

Background: Imaging with Computed tomography perfusion (CTP) in acute stroke has recently started to gain ground, however it requires further validation and whole brain CTP scanners are becoming more available. This study aimed to validate the optimal acute ischemic stroke whole brain CTP pathophysiology parameters. Methods: One hundred and thirteen patients were scanned within 6 hours of ischemic stroke onset with 320 slice CT, which allows concurrent whole brain CTP and dynamic intracranial CT angiography to be derived from the one acquisition. Patients were then followed with a 24 hour MRI sequence that included diffusion weighted imaging (DWI) and dynamic susceptibility weighted perfusion imaging (PWI). Coregistered acute CTP and 24 hour DWI images were then used to define the optimum CTP perfusion threshold for identifying the extent of critically hypoperfused tissue, and infarct core using a pixel based receiver operator curve analysis in patients with and without reperfusion at 24 hours. Results: A time to peak TTP threshold of +5 seconds from contralateral baseline defined the perfusion lesion (AUC 0.79 CI 0.74-0.83) while a Cerebral blood flow &lt; 50% from contralateral baseline best defined the acute infarct core (AUC 0.75, CI, 0.71-0.79). There was no statistically significant difference between the accuracy of thresholds depending on the level or region of the brain to define tissue pathophysiology. Discussion: Whole brain CTP can identify critically hypoperfused tissue and the acute infarct core with excellent accuracy, and finally overcomes the major problem of limited slice coverage with CTP with previous generation CT scanners.

CT im Notarztwagen: technische Aspekte der prähospitalen radiologischen Schlaganfalldiagnostik vor systemischer Thrombolyse

To reduce the time from symptom onset to treatment with tissue plasminogen activator (tPA) in ischemic stroke, an ambulance was equipped with a CT scanner. We analyzed process and image quality of CT scanning during the pilot study regarding image quality and safety issues. The pilot study of a stroke emergency mobile unit (STEMO) ran over a period of 12 weeks on 5 weekdays from 7a.m. to 6:30 p.m. A teleradiological service for the justifying indication and reporting was established. The radiographer was responsible for the performance of the CT scan on the ambulance. 64 cranial CT scans and 1 intracranial CT angiography were performed. We compared times from ambulance alarm to treatment decision (time of last brain scan) with a cohort of 50 consecutive tPA treatments before implementation of STEMO. 62 (95%) of the 65 scans performed had sufficient quality for reading. Technical quality was not optimal in 45 cases (69%) mainly caused by suboptimal positioning of patient or eye lens protection. Motion artefacts were observed in 8 exams (12%). No safety issues occurred for team or patients. 23 patients were treated with thrombolysis. Time from alarm to last CT scan was 18 minutes shorter than in the tPA cohort before STEMO implementation. A teleradiological support for primary stroke imaging by CT on-site is feasible, quality-wise of diagnostic value and has not raised safety issues.

Nontraumatic Subarachnoid Hemorrhage Management: Evaluation with Reduced Iodine Volume at CT Angiography

To evaluate the technical quality and the diagnostic performance of a protocol with use of low volumes of contrast medium (25 mL) at 64-detector spiral computed tomography (CT) in the diagnosis and management of adult, nontraumatic subarachnoid hemorrhage (SAH). This study was performed outside the United States and was approved by the institutional review board. Intracranial CT angiography was performed in 73 consecutive patients with nontraumatic SAH diagnosed at nonenhanced CT. Image quality was evaluated by two observers using two criteria: degree of arterial enhancement and venous contamination. The two independent readers evaluated diagnostic performance (lesion detection and correct therapeutic decision-making process) by using rotational angiographic findings as the standard of reference. Sensitivity, specificity, and positive and negative predictive values were calculated for patients who underwent CT angiography and three-dimensional rotational angiography. The intraclass correlation coefficient was calculated to assess interobserver concordance concerning aneurysm measurements and therapeutic management. All aneurysms were detected, either ruptured or unruptured. Arterial opacification was excellent in 62 cases (85%), and venous contamination was absent or minor in 61 cases (84%). In 95% of cases, CT angiographic findings allowed optimal therapeutic management. The intraclass correlation coefficient ranged between 0.93 and 0.95, indicating excellent interobserver agreement. With only 25 mL of iodinated contrast medium focused on the arterial phase, 64-detector CT angiography allowed satisfactory diagnostic and therapeutic management of nontraumatic SAH.

Basilar artery thrombosis: imaging and endovascular therapy

Basilar artery thrombosis represents a rare type of ischaemic stroke with a mortality rate of 80%-90% if not promptly treated. The aim of our study was to review our experience with computed tomography angiography (CTA) in the diagnosis of basilar artery thrombosis and its treatment with endovascular procedures. Our retrospective study is based upon 59 nontrauma patients with episodes of sudden loss of consciousness. Patients were investigated using unenhanced brain CT followed by intracranial CTA (16-slice CT) when no parenchymal haemorrhage was detected. Patients with a CTA diagnosis of basilar artery thrombosis were considered for endovascular treatment. CTA accuracy was evaluated by considering the 12 patients who underwent endovascular angiography (the gold standard). The success of endovascular therapy was evaluated by considering the degree of microcirculatory reperfusion. After the exclusion of 33 patients affected by parenchymal or subarachnoid haemorrhage, the final study consisted of 26 patients who underwent CTA. Basilar artery thrombosis was diagnosed in 15 of them, and 12 were treated at our institution. The comparison between CTA and endovascular angiography showed 100% agreement in evaluating occlusion site and extension. Seven patients underwent intra-arterial lysis, and five underwent mechanical clot removal. CTA, with its wide availability and rapid execution times, is the most indicated examination in the case of suspected basilar artery thrombosis. Although there is a lack of randomised controlled prospective studies suggesting the most appropriate therapeutic approach to basilar artery thrombosis, our study lends weight to the role of interventional neuroradiology in the treatment of this condition.

Intraoperative computed tomography angiography with computed tomography perfusion imaging in vascular neurosurgery: feasibility of a new concept

In vascular neurosurgery, there is a demand for intraoperative imaging of blood vessels as well as for rapid information about critical impairment of brain perfusion. This study was conducted to analyze the feasibility of intraoperative CT angiography and brain perfusion mapping using an up-to-date multislice CT scanner in a prospective pilot series. Ten patients with unruptured aneurysms underwent intraoperative scanning with a 40-slice sliding-gantry CT scanner. Multimodal CT acquisition was obtained in 8 patients consisting of dynamic perfusion CT (PCT) scanning followed by intracranial CT angiography. Two of these patients underwent CT angiography and PCT 2 times in 1 session as a control after repositioning cerebral aneurysm clips. In another 2 patients, CT angiography was performed alone. The quality of all imaging obtained was assessed in a blinded consensus reading performed by an experienced neurosurgeon and an experienced neuroradiologist. A 6-point scoring system ranging from excellent to insufficient was used for quality evaluation of PCT and CT angiography. In 9 of 10 PCT data sets, the quality was rated excellent or good. In the remaining case, the quality was rated insufficient for diagnostic evaluation due to major streak artifacts induced by the titanium pins of the head clamp. In this particular case, the quality of the related CT angiography was rated good and sufficient for intraoperative decision making. The quality of all 12 CT angiography data sets was rated excellent or good. In 1 patient with an anterior communicating artery aneurysm, PCT scanning led to a repositioning of the clip because of an ischemic pattern of the perfusion parameter maps due to clip stenosis of an artery. The subsequent PCT scan obtained in this patient revealed an improved perfusion of the related vascular territory, and follow-up MR imaging showed only minor ischemia of the anterior cerebral artery territory. Intraoperative CT angiography and PCT scanning were shown to be feasible with short acquisition time, little interference with the surgical workflow, and very good diagnostic imaging quality. Thus, these modalities might be very helpful in vascular neurosurgery. Having demonstrated their feasibility, the impact of these methods on patients' outcomes has now to be analyzed prospectively in a larger series.

Intracranial CT angiography obtained from a cerebral CT perfusion examination

CT perfusion (CTP) examinations of the brain are performed increasingly for the evaluation of cerebral blood flow in patients with stroke and vasospasm after subarachnoid hemorrhage. Of the same patient often also a CT angiography (CTA) examination is performed. This study investigates the possibility to obtain CTA images from the CTP examination, thereby possibly obviating the CTA examination. This would save the patient exposure to radiation, contrast, and time. Each CTP frame is a CTA image with a varying amount of contrast enhancement and with high noise. To improve the contrast-to-noise ratio (CNR) we combined all 3D images into one 3D image after registration to correct for patient motion between time frames. Image combination consists of weighted averaging in which the weighting factor of each frame is proportional to the arterial contrast. It can be shown that the arterial CNR is maximized in this procedure. An additional advantage of the use of the time series of CTP images is that automatic differentiation between arteries and veins is possible. This feature was used to mask veins in the resulting 3D images to enhance visibility of arteries in maximum intensity projection (MIP) images. With a Philips Brilliance 64 CT scanner (64 x 0.625 mm) CTP examinations of eight patients were performed on 80 mm of brain using the toggling table technique. The CTP examination consisted of a time series of 15 3D images (2 x 64 x 0.625 mm; 80 kV; 150 mAs each) with an interval of 4 s. The authors measured the CNR in images obtained with weighted averaging, images obtained with plain averaging, and images with maximal arterial enhancement. The authors also compared CNR and quality of the images with that of regular CTA examinations and examined the effectiveness of automatic vein masking in MIP images. The CNR of the weighted averaged images is, on the average, 1.73 times the CNR of an image at maximal arterial enhancement in the CTP series, where the use of plain averaging increases the CNR only with a factor of 1.49. The quality of the weighted averaged images approaches that of CTA images, although in the present study the image quality of CTA was not quite reached. The automatic masking of veins is effective and only small remnants of veins were sometimes present in the masked images. Weighted averaging makes it possible to create CTA images from a CTP examination with a CNR considerably higher than that of images with maximal arterial enhancement. The quality of the resulting images approaches that of CTA images and offers the additional advantages to automatically differentiate between arteries and veins.

Bilateral vertebral artery dissection and infratentorial stroke complicated by stress-induced cardiomyopathy

A previously healthy 28-year-old Caucasian woman experienced a syncope and was referred to our emergency department. On admission, the patient was neurologically normal and alert. Electrocardiogram (ECG) was normal. Peripheral...

High-concentration contrast media (HCCM) in CT angiography of the carotid system: impact on therapeutic decision making

CT angiography (CTA) is a minimally invasive technique that enables precise delineation of extracranial and intracranial vascular anatomy and pathology based on high intravascular density. With a 64-slice MDCT scanner, improved first-pass vascular visualization can be obtained with HCCM (400 mg I/ml) using 25 ml for combined intra-and extracranial studies and 20 ml for intracranial examinations alone. We reviewed 23 patients with extra-cranial stenoocclusive disease and 12 patients with intra-cranial aneurysms. Two additional patients presented with a mycotic aneurysm and a micro arteriovenous malformation (micro-AVM). In 23 patients with 27 significant (> or =70%) vascular stenoses, high intraluminal contrast density and optimal projection of the stenosis profile facilitated precise delineation of the residual lumen in all vessels affected. Pseudoocclusion was present in 3 of the 27 vessels (11%) and ulceration in 5 (18.5%). CTA, in contrast to digital subtraction angiography (DSA) and magnetic resonance angiography (MRA), was able to delineate the mural constituents of stenoses, particularly marked calcification (present in 17 of 27 vessels, 62.9%). Eccentric vessel wall narrowing indicated dissection in three vessels (11%) and circular postradiation fibrosis was found in two vessels (7.4%). High-quality CTA obviated the need for DSA for diagnostic purposes in every patient. The decision regarding surgical treatment in nine vessels (33%) was influenced by the location of the stenosis relative to the carotid bifurcation, the length of the stenosis, and the level of the carotid bifurcation. Endovascular treatment in 12 vessels (44.4%) and the appropriate choice and placement of endovascular devices was affected by the anatomic configuration of the supraaortic vessels, and by the intrastenotic dimensions relative to the dimensions of the vessel proximal and distal to the stenosis. The anatomic availability of collaterals, relevant for both treatments, was determined via the anterior communicating artery (ACoA) in 91.3% of patients and the posterior communicating artery (PCoA) in 80.4% of patients. Intracranial CTA displayed the lesion location, configuration, size, and orientation in each of the 12 patients with intracranial aneurysms and in the two patients with a micro-AVM and a mycotic aneurysm. The correct diagnosis was established prior to DSA in each patient. Following CTA, the role of DSA was relegated to endovascular therapy in three aneurysms. For surgical candidates, DSA served to exclude potential multiplicity in ten saccular aneurysms and in one mycotic aneurysm. CTA provided information supplementary to DSA in 11 of the 13 aneurysms (84.6%). Delineation of blebs, calcification, thrombus, or incorporation of branches facilitated risk stratification with respect to rupture and to surgical or endovascular treatment. Advantages of CTA, such as virtual independence from the hemodynamic situation, delineation of landmarks and vessel wall calcification, and the ability to quantify vessels and aneurysms, distinguish this technique from other noninvasive vascular imaging techniques and DSA. Acquired with the use of iodinated HCCM, CT angiograms permit excellent recognition of appropriate diagnostic and interventional treatment paths, thereby facilitating improved decision-making regarding endovascular or surgical treatment.

CT Angiography in Acute Stroke – Does It Provide Additional Information on Occurrence of Infarction and Functional Outcome after 3 Months?

Objective: To investigate whether acute phase intracranial CT angiography (CTA) independently predicts infarction and functional outcome in ischemic stroke. Methods: Hundred and fifty-one consecutive patients with acute (<12 h) ischemic stroke who received intracranial CTA were investigated. Stroke severity on admission was determined using the National Institute of Health Stroke Scale (NIHSS). Reconstructed CTAs were investigated for relevant pathology. Follow-up imaging was performed 24–48 h after admission. Functional outcome was assessed after 3 months using the modified Rankin scale. Single factor and multiple logistic regression analyses were performed to predict infarction and dependency (modified Rankin scale ≧ 3) on follow-up. Results: Median NIHSS on admission was 10 (IQR 3–14). Out of the 151 patients, 61 (40%) had pathological CTA findings. Infarction was demonstrated in 60/61 patients (98%) with and in 67/90 patients (74%) without vessel pathology. Presence of infarction on follow-up imaging and dependency at 3 months were correlated with pathological CTA findings on admission in single factor analysis (each p < 0.001). After adjustment for age (≧/<65 years), NIHSS (≧/<10), sex, therapy, and time to presentation (≧/<3 h), only NIHSS ≧10 on admission was predictive of dependency at follow-up (p < 0.001). Conclusions: Pathological CTA findings in the acute phase of ischemic stroke do not independently predict a poor outcome at 3 months after acute stroke.

Graphic Profiles of Cerebral Perfusion in Dynamic CT Imaging of Hyperacute Ischaemic Stroke

Ischaemic stroke accounts for 80% of cerebrovascular disease. It is the third commonest cause of death, the second cause of dementia and the primary cause of disability. The widespread availability of CT scanning, the speed of examination and its low cost make CT the gold standard for early diagnosis of stroke before the mechanisms of cell swelling are triggered heralding irreversible neuronal damage. CT scanning allows morphological assessment of brain parenchyma demonstrating or excluding any bleeding and direct or indirect signs of ischaemia. It also allows perfusion imaging to display the cerebral territory at risk. Our study aimed to devise a dynamic CT perfusion imaging technique for use on an ordinary spiral CT system to be combined with morphological study and head and neck CT angiography to disclose the cause of the stroke correlated to clinical findings. Eighty patients with transient and permanent clinical forms of acute ischaemic stroke were referred to our institution within 0.5 to eight hours after clinical onset of symptoms. All patients underwent standard CT scan followed by CT perfusion imaging, intracranial CT angiography, neck CT angiography and brain CT scan after contrast administration. Each patient received a 40 ml bolus of iodate contrast agent for each examination for a total of 120 ml at a concentration of 300 mg/ml. CT perfusion imaging yielded a graph obtained over a ROI centred on the lentiform nuclei showing the peak time (PT) equal to the mean transit time (MTT) and dependent on cerebral blood flow (CBF). The graphic profiles of perfusion correlated to clinical findings and intra and extracranial CT angiography MIP reconstructions demonstrated the etiopathogenesis of stroke, the vascular territory affected and the prognosis. Combined with morphological study of brain parenchyma, CT angiography and clinical findings, CT perfusion graphs offer an immediate diagnosis of hyperacute ischaemic stroke allowing prompt therapeutic decisions to improve the prognosis.

Intracranial CT Angiography with Spiral CT: Preliminary Report

Intracranial CT Angiography with Spiral CT: Preliminary Report