Whole-brain CT Perfusion Research Articles

Whole-Brain CT Perfusion and CT Angiography Assessment of Moyamoya Disease before and after Surgical Revascularization: Preliminary Study with 256-Slice CT

Background/AimsThe 256-slice CT enables the entire brain to be scanned in a single examination. We evaluated the application of 256-slice whole-brain CT perfusion (CTP) in determining graft patency as well as investigating cerebral hemodynamic changes in Moyamoya disease before and after surgical revascularization.MethodsThirty-nine cases of Moyamoya disease were evaluated before and after surgical revascularization with 256-slice CT. Whole-brain perfusion images and dynamic 3D CT angiographic images generated from perfusion source data were obtained in all patients. Cerebral blood flow (CBF), cerebral blood volume (CBV), time to peak (TTP) and mean transit time (MTT) of one hemisphere in the region of middle cerebral artery (MCA) distribution and contralateral mirroring areas were measured. Relative CTP values (rCBF, rCBV, rTTP, rMTT) were also obtained. Differences in pre- and post- operation perfusion CT values were assessed with paired t test or matched-pairs signed-ranks test.ResultsPreoperative CBF, MTT and TTP of potential surgical side were significantly different from those of contralateral side (P<0.01 for all). All graft patencies were displayed using the 3D-CTA images. Postoperative CBF, rCBF and rCBV values of surgical side in the region of MCA were significantly higher than those before operation (P<0.01 for all). Postoperative MTT, TTP, rMTT and rTTP values of the surgical side in the region of MCA were significantly lower than those before operation (P<0.05 for all).ConclusionThe 256-slice whole-brain CTP can be used to evaluate cerebral hemodynamic changes in Moyamoya disease before and after surgery and the 3D-CTA is useful for assessing the abnormalities of intracranial arteries and graft patencies.

Assessment of the Tracer Delay Effect in Whole-Brain Computed Tomography Perfusion

Whole-brain computed tomography perfusion (CTP) data sets generated by tracer delay-insensitive singular value decomposition plus (SVD+) and standard singular value decomposition (sSVD) deconvolution algorithms were evaluated to quantify relatedness and discrepancies in CTP results. Twenty females with symmetrical hemispheric CTP maps indicative of brain tissue without apparent abnormalities were studied. Tissue-specific CTP values were analyzed. Standard SVD values were higher than SVD+ for cerebral blood flow. Other CTP values had minimal differences across brain regions. All simple linear regression models were statistically significant (P < 0.05) except for cerebral blood flow in white matter (P = 0.06). Cerebral blood volume had a good model fit, and mean transit time, a poor fit. Corresponding fitted CTP values for sSVD and SVD+ based on regression equations for brain-tissue types are presented. Additional research is required to compare SVD+ and sSVD in disease states when significant hemodynamic brain alterations are present.

Assessment of Tracer Delay Effect in Whole-Brain Computed Tomography Perfusion

The objective of this study was to compare the variability of computed tomography perfusion (CTP) results in identical data sets of middle cerebral artery (MCA) acute ischemic stroke (AIS) generated by standard singular value decomposition (sSVD) deconvolution and tracer delay-insensitive singular value decomposition (SVD+) algorithm analyses. Whole-brain 320-detector-row CTP data sets from 9 unilateral MCA AIS cases and 9 controls were retrospectively analyzed. Computed tomography perfusion values for the combined core/penumbra, contralateral hemispheres and arterial territories were measured and compared with literature values. Simple linear regression models are provided to predict corresponding SVD+ value and sSVD CTP values. In the core/penumbra, sSVD generated lower cerebral blood flow (CBF) values, higher mean transit time (MTT) values, and a broader range of CBF and MTT values as compared with SVD+. Mean transit time value differences between the core/penumbra and contralateral hemispheres were statistically significant using sSVD, whereas those of SVD+ were not. Goodness of fit between algorithms for the core/penumbra was lower for CBF (0.483) and MTT (0.494), as compared with time to peak (0.891) and cerebral blood volume (0.997). In this study using identical source data for patients with MCA AIS, use of either sSVD or SVD+ analyses created statistically significant differences in the CTP value results. Tracer delay-sensitive and -insensitive algorithms impact CTP results in AIS and controls, highlighting the need to pursue additional studies that assess the variability, accuracy, and clinical implications of CTP results generated when using heterogeneous deconvolution algorithms.

Correction

HomeStrokeVol. 43, No. 5Correction Free AccessCorrectionPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessCorrectionPDF/EPUBCorrection Originally published1 May 2012https://doi.org/10.1161/STR.0b013e3182574d16Stroke. 2012;43:e54This article corrects the followingGrading Carotid Stenosis Using Ultrasonic MethodsThe article entitled, “Grading Carotid Stenosis Using Ultrasonic Methods,” by von Reutern et al, which published in the March 2012 issue of the journal (Stroke. 2012;43:916–921), included an error in the running head of the article (on pages 917, 919, and 921). The running head should be: “Grading Carotid Stenosis” Also, in the author's list Dr von Reutern's name appeared twice. Dr von Reutern is the first author. These errors have been corrected in the online version of the article and Table of Contents. Previous Back to top Next FiguresReferencesRelatedDetailsCited By Hanson E, Roach C, Day K, Ghosh K, Peters K, Bradley W and Orrison W (2013) Assessment of Tracer Delay Effect in Whole-Brain Computed Tomography Perfusion, Journal of Computer Assisted Tomography, 10.1097/RCT.0b013e318280a465, 37:2, (222-232), . Hanson E, Roach C, Day K, Peters K, Bradley W, Ghosh K, Patton P, McMurray R and Orrison W (2013) Assessment of the Tracer Delay Effect in Whole-Brain Computed Tomography Perfusion, Journal of Computer Assisted Tomography, 10.1097/RCT.0b013e31828004bb, 37:2, (212-221), . Related articlesGrading Carotid Stenosis Using Ultrasonic MethodsGerhard-Michael von Reutern, et al. Stroke. 2012;43:916-921 May 2012Vol 43, Issue 5 Advertisement Article InformationMetrics © 2012 American Heart Association, Inc.https://doi.org/10.1161/STR.0b013e3182574d16 Originally publishedMay 1, 2012 PDF download Advertisement

Role of Mean Transit Time (MTT) Perfusion Map on the Aquilion ONE CT Scanner Using SVD+ Algorithm in Acute Stroke (P07.035)

Objective: MTT map is a sensitive and specific map differentiating ischemic penumbra (IP) from infarct core (IC) in acute stroke. Background We present eight patients with acute ischemic stroke who presented to our emergency department and underwent computed tomography perfusion (CTP) imaging utilizing the Toshiba Aquilion ONE 320-dectector row CT scanner running a Singular Value Decomposition Plus (SVD+) algorithm to generate perfusion maps. Design/Methods: A retrospective analysis of patients who presented with an acute ischemic stroke was performed. Patients receiving a high quality whole-brain CTP scan without evidence of hemorrhage on initial or follow-up CT who additionally underwent follow up MRI with DWI within 48 hours were included. Vitrea FX 3.1 software was utilized by a single, blinded neuroradiologist to process images. At risk territory was defined by the area of delayed perfusion on the time to peak map. The IC volume on the MTT map, as determined by values less than 3 seconds within this at risk territory, was measured on each slice. The total IC volumes were calculated by taking the sum of the IC on individual slices multiplied by the thickness of each slice. Pearson correlation was applied to assess for statistical correlation between IC on CTP and area of restriction on follow up DWI. Results: A comparison was made between the volumes of infarct core utilizing SVD+ MTT maps and DWI MR sequences. There was a significant correlation between infarct core volumes measured on MTT and infarct volumes on follow up DWI (r = 0.79). Conclusions: Although further studies are required to validate this observation, preliminary studies suggest that utilization of the SVD+ MTT map may allow for an accurate assessment of the infarct core and surrounding salvageable tissue. The additional information garnered from accurate interpretation of the SVD+ MTT maps may further guide clinicians in critical decision making during acute ischemic events. Disclosure: Dr. Dababneh has nothing to disclose. Dr. Guerrero has nothing to disclose. Dr. Wilson has nothing to disclose. Dr. Mocco has received personal compensation for activities with Concentric Inc as a consultant. Dr. Bennett has nothing to disclose. Dr. Hoh has received personal compensation for activities with Codman Neurovascular. Dr. Yuzeforich-Khanna has nothing to disclose. Dr. Peters has received personal compensation for activities with Toshiba as a speaker. Dr. Waters has nothing to disclose.

256-slice whole-brain CT perfusion in assessment of graft reperfusion after surgical revascularization and hemodynamic alterations before and after surgery in Moyamoya disease

Objective To explore the feasibility of 256-slice whole-brain CT perfusion (CTP) in evaluate graft reperfusion after surgical revascularization and hemodynamic alterations before and after surgery in Moyamoya disease. Methods Twenty-five cases with Moyamoya disease were scanned on a 256-slice CT.CTP was performed pre- and post- surgical revascularization. The wolumetric CT angiographic ( CTA ) images were generated from volumetric data acquired at the arterial phase of CTP. CBF, CBV, TTP and MTT were measured in functional maps at the operated side within middle cerebral artery perfusion areas and contralateral mirroring areas. Relative CBF( rCBF), relative CBV (rCBV), relative TTP (rTTP), relative MTT (rMTT) were also obtained. Differences in perfusion CT values pre- and post operation were assessed with the paired t test or matched-pairs signed-ranks test. Data with normal distribution was present as : (x-)± s,while those with the non-normal distribution were present as M ( P25-P75 ). Results All the direct graft patencies were displayed on volumetric CTA. No significant differences were found between volumetric CTA and conventional CTA. Postoperative CBF, rCBF and rCBV values of the operated side [ 72. 86 (55.54-112. 19) ml · 100 g-1 · min-1 , 1. 31 ( 1.05-1.73), 1.45 ±0. 62] were significantly higher than those before operation [46.72(28.57-57.67) ml · 100 g-1 · min-1, 0.53(0.33-0.82), 1.01 ±0.36](Z=- 2.72, - 2. 98, t = - 2. 85, P ＜ 0. 05 ). Postoperative MTT, TTP and rTTP values of the operated side [ (3.98 ± 2. 36 ) s, ( 17.56 ± 4. 38 ) s, 1.01 ± 0. 09 ] were significantly lower than those before operation [(5.43±2.07) s,(19.40±3.87) s,1.14±0.28] (t=2.41,2.17,2.17, respectively, P＜0.05).However, no significant differences were detected for changes of CBV and rMTT after revascularization ( P ＞0. 05). Conclusion 256-slice CT has the potential value for the non-invasive assessment of both the graft patency and cerebral hemodynamics changes in moyamoya disease after surgery with administration of one contrast medium bolus in a single examination. Key words: Moyamoya disease; Tomography,X-ray computed; Cerebral revascularization

Management of patients with intracerebral hemorrhage due to aneurysm rupture

Ischemic complications associated with microsurgical clipping and endovascular coiling affects the outcome of patients with intracranial aneurysms. We prospectively evaluated 58 intracranial aneurysm patients who had neurological deterioration or presented with poor grade (Hunt-Hess grades III and IV), aneurysm size >13 mm and multiple aneurysms after clipping or coiling. Thirty patients had ischemic complications (52%) as demonstrated by whole-brain CT perfusion (WB-CTP) combined with CT angiography (CTA). Half of these 30 patients had treatment-associated reduction in the diameter of the parent vessels (n = 6), ligation of the parent vessels or perforating arteries (n = 2), and unexplained or indistinguishable vascular injury (n = 7); seven of these 15 (73%) patients suffered infarction. The remaining 15 patients had disease-associated cerebral ischemia caused by generalized vasospasm (n = 6) and focal vessel vasospasm (n = 9); six of these 15 (40%) patients developed infarction. Three hemodynamic patterns of ischemic complications were found on WB-CTP, of which increased time to peak, time to delay and mean transit time associated with decreased cerebral blood flow and cerebral blood volume were the main predictors of irreversible ischemic lesions. In conclusion, WB-CTP combined with CTA can accurately determine the cause of neurological deterioration and classify ischemic complications. This combined approach may be helpful in assessing hemodynamic patterns and monitoring operative outcomes.

Appearance and impact of post-operative intracranial clips and coils on whole-brain CT angiography and perfusion

To evaluate the effect of vascular clips and endovascular coils placed for intracranial aneurysms and arteriovenous malformations on whole-brain computed tomography (CT) angiography and perfusion. A 320-detector row dynamic volume CT system imaged 11 patients following surgical placement of vascular clips or endovascular coils. The extent of clip and coil subtraction by automated software was evaluated using CT digital subtraction angiography and CT perfusion. Impact on CT perfusion values by retained intracranial devices was compared to age- and gender-matched controls. Clip and coil subtraction on CT angiography was graded as good in 8 and moderate in 3 cases. A residual neck and additional aneurysm were noted in 1 of 11 patients. Post-procedural axial slice level CT perfusion values decreased in reliability with increasing proximity to the metallic devices secondary to beam hardening. However, the intracranial devices did not affect axial slice level CTP values of cerebral blood volume, cerebral blood flow and mean transit time outside of the level of the device. Time to peak values was globally decreased outside of the immediate vascular intervention region. Advances in CT technology have provided clinically useful subtraction of intracranial clips and coils. While CT perfusion values were altered in device subtraction areas and within beam hardening artifact areas; they can provide valuable postoperative information on whole-brain hemodynamics. In selected cases, the combination of CT angiography and whole-brain CT perfusion can offer an alternative to conventional angiography that is a more invasive option.

Quantitative Evaluation of the Penumbra and Ischemic Core in Acute Cerebral Infarction Using Whole-Brain CT Perfusion

The objectives of the study were to quantitatively assess whole-brain CT Perfusion (CTP) data using an automatic region of interest (ROI) analysis program in order to distinguish between the degree of ischemia in the ischemic core and that in the penumbra and to assess the relationship between expansion of the area of infarction. The subjects were 20 patients with acute cerebral infarction. Whole-brain CTP was performed for all subjects using a 320-row area detector CT scanner. The penumbra* is defined as the region in which the CBV value is 2 mL/100 g or more and the ischemic core* is defined as the region in which the CBV value is less than 2 mL/100 g. The quantitative values of CTP parameters were automatically measured using the automatic ROIs analysis program. The Mann-Whitney U test was applied to differentiate between the ischemic core* and the penumbra*. The reduction in perfusion pressure in the penumbra* was smaller in the group with expansion of the area of infarction than in the group without expansion of the area of infarction. The difference in the median values between the penumbra* and the ischemic core* was larger in the group with expansion of the area of infarction than the group without expansion of the area of infarction. It is considered that the quantitative analysis method using whole-brain CTP may be useful for more accurately distinguishing between the ischemic core and the penumbra and for evaluating the risk of expansion of the ischemic core into the penumbra.

Observation of Mean Transit Time (Mtt) Perfusion Maps on a 320-Detector Row Ct Scanner and its Potential Application in Acute Ischemic Stroke

Background and Purpose: We present three patients with acute ischemic stroke who underwent computed tomography perfusion (CTP) imaging utilizing an Aquilion ONE (Toshiba Medical Systems, Nasu, Japan) 320-dectector row CT scanner using a Singular Value Decomposition Plus (SVD+) algorithm to generate perfusion maps. These MTT maps may prove to be a sensitive and specific predictor of ischemic penumbra (IP) and infarct core (IC). Methods: Patients, who presented with an acute ischemic stroke, received high quality whole-brain CTP scans and a follow up MRI or non-contrast CT (NCCT) scan, and underwent successful pharmacological and/ or interventional reperfusion procedures were selected for evaluation. A neuroradiologist utilizing Vitrea FX 3.1 software reviewed images, and the IC volumes were calculated. Results: A comparison was made between the volumes of infarct core utilizing SVD+ MTT maps and DWI MR sequences or a sub-acute NCCT. There was a correlation between the infarct core volume measured on MTT and final infarct volume on follow up imaging. However due to limitations associated with a small sample size, a statistical correlation cannot be definitively calculated from this data set. Conclusions: Utilization of the SVD+ MTT map may allow for a more accurate assessment of the infarct core and surrounding salvageable tissue as compared to cerebral blood flow/cerebral blood volume (CBF/CBV) mismatch though further studies are required to validate this observation.

Whole-Brain Perfusion Measurement Using 320-Detector Row Computed Tomography in Patients With Cerebrovascular Steno-Occlusive Disease

The 320-detector row computed tomography (CT) can provide whole-brain CT perfusion (CTP) maps with continuous angiographic images by performing a single dynamic scan. We investigated the reliability of CTP cerebral blood flow (CTP-CBF) with 320-detector row CT by comparing findings with O-positron emission tomography (PET-CBF). Whole-brain CTP and PET were performed in 10 patients with chronic unilateral steno-occlusive disease. We compared absolute and relative CBF values of bilateral middle cerebral artery territories between CTP and PET. Although mean CTP-CBF values were approximately 30% lower than mean PET-CBF values, the mean ischemic-to-nonischemic CBF ratios of CTP and PET were almost identical (P = 0.804). Regression analysis showed a significant correlation between CTP-CBF and PET-CBF values for each patient (r = 0.52-0.85, P < 0.001). Whole-brain CTP using 320-detector row CT is useful for evaluating the degree of ischemia for the entire brain with chronic cerebrovascular disease.

Developmental venous anomalies: appearance on whole-brain CT digital subtraction angiography and CT perfusion

IntroductionDevelopmental venous anomalies (DVA) consist of dilated intramedullary veins that converge into a large collecting vein. The appearance of these anomalies was evaluated on whole-brain computed tomography (CT) digital subtraction angiography (DSA) and CT perfusion (CTP) studies.MethodsCT data sets of ten anonymized patients were retrospectively analyzed. Five patients had evidence of DVA and five age- and sex-matched controls were without known neurovascular abnormalities. CT angiograms, CT arterial-venous views, 4-D CT DSA and CTP maps were acquired on a dynamic volume imaging protocol on a 320-detector row CT scanner. Whole-brain CTP parameters were evaluated for cerebral blood flow (CBF), cerebral blood volume (CBV), time to peak (TTP), mean transit time (MTT), and delay. DSA was utilized to visualize DVA anatomy. Radiation dose was recorded from the scanner console.ResultsIncreased CTP values were present in the DVA relative to the unaffected contralateral hemisphere of 48%, 32%, and 26%; and for the control group with matched hemispheric comparisons of 2%, −10%, and 9% for CBF, CBV, and MTT, respectively. Average effective radiation dose was 4.4 mSv.ConclusionWhole-brain DSA and CTP imaging can demonstrate a characteristic appearance of altered DVA hemodynamic parameters and capture the anomalies in superior cortices of the cerebrum and the cerebellum. Future research may identify the rare subsets of patients at increased risk of adverse outcomes secondary to the altered hemodynamics to facilitate tailored imaging surveillance and application of appropriate preventive therapeutic measures.

320-Multidetector row whole-head dynamic subtracted CT angiography and whole-brain CT perfusion before and after carotid artery stenting: Technical note

Introduction Multidetector CT (MDCT) is increasingly used for the investigation of neurovascular disorders, but restricted z-axis coverage (3.2 cm for 64-MDCT) currently limits perfusion to a small portion of the brain close to the circle of Willis, and precludes dynamic angiographic appreciation of the entire brain circulation. We illustrate the clinical potential of recently developed 320-MDCT extending the z-axis coverage to 16 cm in a patient with symptomatic carotid artery stenosis. Methods In a 74-year-old patient presenting with critical symptomatic stenosis of the left CCA, pre- and post-carotid artery stenting whole-head subtracted dynamic MDCT angiography and perfusion were obtained in addition to CT angiography of the supra-aortic trunks. Both whole-head subtracted MDCT angiography and perfusion demonstrated delayed left ICA circulation, which normalized after carotid stenting. Discussion 320-MDCT offers unprecedented z-axis coverage allowing for whole-brain perfusion and subtracted dynamic angiography of the entire intracranial circulation. These innovations can consolidate the role of MDCT as a first intention imaging technique for cerebrovascular disorders, in particular for the acute management of stroke.

320-slice CT neuroimaging: initial clinical experience and image quality evaluation

The aim of this study was to report initial clinical experience with a 320-slice CT scanner and to perform an image quality evaluation. 26 patients with presumptive cerebrovascular pathology underwent 320-slice CT. Single-rotation CT of the head, incremental CT angiography (three-dimensional (3D) CTA) as well as four-dimensional whole-brain CTA (4D CTA) and whole-brain CT perfusion (CTP) were performed and the resulting images were assessed for quality and compared with those obtained with 64-slice CT protocols. 320-slice CT neuroimaging could be performed in all cases. The image quality of 320-slice CT of the head and 3D CTA was inferior to that of the 64-slice protocols. The image quality of 4D 320-slice CTA was rated as inferior to both 320- and 64-slice 3D CTA. 4D CTA-CTP imaging added information with pivotal clinical implications. 320-slice CT neuroimaging is feasible technique that permits whole-brain 4D imaging and has the potential to identify pathologies with altered haemodynamics. However, image quality is a limitation of this technique at present.

Whole-brain CT perfusion measurement of perfused cerebral blood volume in acute ischemic stroke: probability curve for regional infarction.

To determine the probability curve for regional cerebral infarction as a function of percentage normalized perfused cerebral blood volume (pCBV) in patients with acute ischemic stroke. The authors retrospectively analyzed whole-brain computed tomographic (CT) perfusion scans from 28 patients with acute stroke (<6 hours) due to major arterial occlusion, without intracranial hemorrhage. Each patient had a positive follow-up CT scan 1-4 days later, without interval thrombolysis. Normalized pCBV, expressed as a percentage of contralateral normal brain pCBV, was determined in the core infarction and in regions just inside and outside the boundary between infarcted and noninfarcted brain. These regions were dichotomized into infarcted (core and inner band) and noninfarcted (outer band) categories. Logistic regression analysis was then used to create a reference curve of probability of infarction as a function of percentage normalized pCBV. Normalized pCBV values in the core, inner band, and outer band were 24.5% +/- 2.3, 36.3% +/- 2.4, and 72.1% +/- 2.4, with corresponding probabilities of infarction of .99, .96, and .11. The normalized pCBV at which the probability of survival reached .5 was 58.0% +/- 0.5. Sensitivity, specificity, and accuracy of the reference probability curve were 90.5% (209 of 231), 89.5% (212 of 237), and 90.0% (421 of 468), respectively. Negative and positive predictive values were 90.6% (212 of 234) and 89.3% (209 of 234), respectively. R2 was 0.73, and differences in perfusion between core and inner and outer bands were highly significant (P <.0001). A probability of infarction curve can help predict the likelihood of infarction as a function of percentage normalized pCBV.

Potential Influence of Acute CT on Inpatient Costs in Patients with Ischemic Stroke

Rationale and Objectives Patients presenting with ischemic brain symptoms have widely variable outcomes dependent to some degree on the pathologic basis of their stroke syndrome. The purpose of this study was to determine the cost implications of the emergency use of a computed tomographic (CT) protocol comprising unenhanced CT, head and neck CT angiography, and whole-brain CT perfusion. Materials and Methods By using a retrospective patient database from a tertiary care facility and publicly available cost data, the authors derived the potential savings from the use of CT angiography, CT perfusion, or both at hospital arrival by means of a cost model. The cost of the CT angiography–CT perfusion protocol was determined from Medicare reimbursement rates and compared with that of traditional imaging protocols. Cost savings were estimated as a decrease in the length of stay for most stroke patients, whereas the most benign (lacunar) strokes were assumed to be managed in a nonacute setting. Misdiagnosis cost (erroneously not admitting a patient with nonlacunar stroke) was calculated as the cost of a severe complication. Sensitivity testing included varying the percentage of misdiagnosed patients and admitting patients with lacunar stroke. Results The nationwide net savings that would result from the adoption of the CT angiography–CT perfusion protocol are in the $1.2 billion range (−$154 million to $2.1 billion) when patients with lacunar strokes are treated nonacutely and $1.8 billion when those patients are admitted for acute care. Conclusion The results demonstrate the potential effect of implementing a CT angiography–CT perfusion protocol. In particular, prompt CT angiography–CT perfusion imaging could have an effect on the cost of acute care in the treatment of stroke.