Variability of clinical CT perfusion measurements in patients with carotid stenosis

Introduction CT perfusion imaging (pCT) may be used to detect and monitor hemodynamic abnormalities due to cerebrovascular disease. The magnitude of variability in clinical measurements has been insufficiently evaluated. The purpose of this study was to measure the long-term variability of clinical pCT measurements in patients with cerebrovascular disease. Methods pCT parameters were calculated for the cerebral hemisphere contralateral to a carotid stenosis before and after stent treatment of stenosis in 33 consecutive patients. Mean transit time (MTT), cerebral blood flow (CBF), and cerebral blood volume (CBV) calculated from pCT data from both a small and large region of interest (ROI) using both manual and automated methods were compared before and after stent treatment. Differences between the first and second measurement were tested for statistical significance with at-test. Variability was calculated as the standard deviation of the differences divided by the mean of the pre- and post-stent treatment values. To adjust for proportional bias, the Bland–Altman analysis was applied. Results The differences between the two measurements of MTT, CBF, and CBV averaged 2.5 to 7.7% when a manual method was used and was higher with automatic methods (p > 0.07). The variability of the values was 18% for MTT, 19% for CBV, and 25% for CBF with the large ROI and the manual method of calculation. The magnitude was larger when the small ROI and automatic methods were employed. Conclusion Longitudinal measurements of MTT, CBV, or CBF by pCT may vary by 20–25%. To detect changes in treatment-related changes in perfusion, pCT studies must be designed to achieve statistical significance based on this variability.     

Prognostic value of perfusion- and diffusion-weighted MR imaging in first 3 days of stroke

The aim of this study was to evaluate the differences in cerebral perfusion seen on mean transit time (MTT) and cerebral blood volume (CBV) maps and to assess the subsequent prognostic value of the MTT–DWI (diffusion-weighted MRI) and CBV–DWI mismatch in the first three days of stroke on lesion enlargement and clinical outcome. In 38 patients, imaged 1–46 h after onset of symptoms, lesion volumes on proton-density (PD)-weighted MRI, DWI and PWI (both MTT and CBV maps) were compared with lesion volumes on follow-up PD-weighted scans, and to clinical outcome (National Institutes of Health Stroke Scale, Barthel index, and Rankin scale). The MTT-CBV, MTT–DWI and CBV–DWI mismatches were compared with change in lesion volume between initial and follow-up PD-weighted scans. Lesion volume on both DWI and PWI correlated significantly with clinical outcome parameters (p < 0.001) with strongest correlation for lesion volume on CBV. Perfusion–diffusion mismatches were found for both CBV and MTT and correlated significantly with lesion enlargement on PD-weighted imaging with strongest correlation for the CBV–DWI mismatch. The CBV–DWI mismatch has the highest accuracy in predicting lesion size on follow-up imaging and in predicting clinical outcome. Lesion volume measurements on CBV maps have a higher specificity than on PD-weighted, MTT or DWI images in predicting clinical follow-up imaging and in predicting clinical outcome. Received: 21 January 2000; Revised: 18 April 2000; Accepted: 20 April 2000     

Prediction of clinical outcome with baseline and 24-hour perfusion CT in acute middle cerebral artery territory ischemic stroke treated with intravenous recanalization therapy

Introduction We sought to determine whether Alberta Stroke Program Early CT Scores (ASPECTS) derived from baseline noncontrast CT (NCCT) and perfusion CT (CTP) imaging maps can predict clinical outcome after recanalization therapy in acute ischemic stroke of the middle cerebral artery (MCA) territory and whether changes in the ASPECTS from baseline to 24 h after recanalization therapy can help predict clinical outcome. Methods We retrospectively studied consecutive patients with acute ischemic stroke of the MCA territory treated with intravenous tissue plasminogen activator (t-PA) or abciximab within 6 h of symptom onset. We performed NCCT and CTP before and 24 h after intravenous t-PA or abciximab treatment and determined the ASPECTS and the changes in the ASPECTS from baseline to 24 h. A favorable outcome was defined as a modified Rankin scale score of 0 or 1 at 3 months. Results During the 18-month study period 44 patients were studied. In multivariate logistic regression analysis, the cerebral blood volume (CBV) ASPECTS (OR 1.80, 95% CI 1.10 to 2.93) at baseline and the increase in cerebral blood flow (CBF) ASPECTS (OR 1.68, 95% CI 1.13 to 2.50) from baseline to 24 h were associated with a favorable outcome. The cutoff values for a favorable outcome using receiver operating characteristic curves were 8 and 1, respectively. When the CBV ASPECTS at baseline was 8 or more, its positive predictive value was only 58.1%. When the CBV ASPECTS at baseline was 8 or more and the increase in CBF ASPECTS from baseline to 24 h was 1 or more, the positive predictive value was 100% and the negative predictive value was 74.2%. Conclusion The CBV ASPECTS derived from baseline CTP maps was found to be predictive of a favorable outcome, but its positive predictive value was suboptimal. The change in the CBF ASPECTS from baseline to 24 h after treatment was helpful in predicting outcome.     

Automated versus manual post-processing of perfusion-CT data in patients with acute cerebral ischemia: influence on interobserver variability

Introduction  The purpose of this study is to compare the variability of PCT results obtained by automatic selection of the arterial input function (AIF), venous output function (VOF) and symmetry axis versus manual selection. Methods  Imaging data from 30 PCT studies obtained as part of standard clinical stroke care at our institution in patients with suspected acute hemispheric ischemic stroke were retrospectively reviewed. Two observers performed the post-processing of 30 CTP datasets. Each observer processed the data twice, the first time employing manual selection of AIF, VOF and symmetry axis, and a second time using automated selection of these same parameters, with the user being allowed to adjust them whenever deemed appropriate. The volumes of infarct core and of total perfusion defect were recorded. The cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT) and blood–brain barrier permeability (BBBP) values in standardized regions of interest were recorded. Interobserver variability was quantified using the Bland and Altman's approach. Results  Automated post-processing yielded lower coefficients of variation for the volume of the infarct core and the volume of the total perfusion defect (15.7% and 5.8%, respectively) compared to manual post-processing (31.0% and 12.2%, respectively). Automated post-processing yielded lower coefficients of variation for PCT values (11.3% for CBV, 9.7% for CBF, and 9.5% for MTT) compared to manual post-processing (23.7% for CBV, 32.8% for CBF, and 16.7% for MTT). Conclusion  Automated post-processing of PCT data improves interobserver agreement in measurements of CBV, CBF and MTT, as well as volume of infarct core and penumbra.     

CT灌注原始图像不匹配模型评价急性缺血性脑卒中缺血半暗带和梗死核心的价值

目的 评价CT灌注原始图像(CT perfusion source images,CTP-SI)不匹配模型在判断缺血半暗带和梗死核心中的价值.方法 24例急性缺血性脑卒中患者(发病时间＜9 h)行"一站式急性缺血性脑卒中CT"扫描,分析基线动脉期及静脉期CTP-SI Alberta卒中早期CT评分(Alberta Stroke Program Early CT Score,ASPECTS),并与随访影像ASPECTS进行对照.采用Wilcoxon秩和检验比较动脉期与静脉期CTP-SI ASPECTS之间的统计学差异;应用多元线性回归分析基线动脉期、静脉期CTP-SI与随访影像ASPECTS之间的线件依存关系.结果 基线动脉期、静脉期和随访影像的CTP-SI ASPECTS中位数分别为9.0分(2.0～10.0分)、9.3分(6.5～10.0分)、9.0分(7.0～10.0分).动脉期与静脉期CTP-SI ASPECTS差异有统计学意义(Z=-2.812,P=0.005),10例静脉期CTP-SI ASPECTS大于动脉期,14例静脉期CTP-SI ASPECTS等于动脉期;静脉期CTP-SIASPECTS与随访影像ASPECTS之间的线性依存关系有统计学意义,标准化回归系数(Beta)=0.715,P=0.003.结论 CT灌注原始图像不匹配模型可以预测缺血半暗带和梗死核心,为临床医师制定治疗方案时提供了更多的选择.     

Differentiation of total occlusion and high-grade stenosis in coronary CT angiography

In coronary CT angiography (CTA), both high-grade stenoses and total occlusions of a coronary artery may appear as a complete interruption of the contrast-enhanced lumen. Parameters to differentiate between occlusions and stenoses have not been systematically assessed. We evaluated 40 consecutive patients with a lesion demonstrating complete interruption of the contrast-enhanced lumen in coronary CTA and in whom invasive coronary angiography was available. Length of the vessel segment without luminal contrast enhancement; luminal enhancement proximal, in and distal to the lesion; degree of coronary remodelling; and the degree of lesion calcification were assessed by a blinded observer unaware of the invasive angiogram. Mean length of complete occlusions (n = 20; range 4–54 mm; mean 16.6 ± 3.5 mm) was significantly longer than for high-grade stenoses (n = 20; 2–8 mm; mean 4.6 ± 1.7 mm, p < 0.001). A lesion length ≥ 9 mm was 100% specific and 70% sensitive for an occlusion. No significant differences were found for vessel enhancement in or distal to the lesion, remodelling index or degree of calcification. Lesion length is the only parameter that may differentiate complete occlusions and high-grade stenoses in coronary CTA. For lesions ≥ 9 mm, an occlusion is very likely.     

CT colonography: optimisation,diagnostic performance and patient acceptability of reduced-laxative regimens using barium-based faecal tagging

To establish the optimum barium-based reduced-laxative tagging regimen prior to CT colonography (CTC). Ninety-five subjects underwent reduced-laxative (13 g senna/18 g magnesium citrate) CTC prior to same-day colonoscopy and were randomised to one of four tagging regimens using 20 ml 40%w/v barium sulphate: regimen A: four doses, B: three doses, C: three doses plus 220 ml 2.1% barium sulphate, or D: three doses plus 15 ml diatriazoate megluamine. Patient experience was assessed immediately after CTC and 1 week later. Two radiologists graded residual stool (1: none/scattered to 4: >50% circumference) and tagging efficacy for stool (1: untagged to 5: 100% tagged) and fluid (1: untagged, 2: layered, 3: tagged), noting the HU of tagged fluid. Preparation was good (76–94% segments graded 1), although best for regimen D (P = 0.02). Across all regimens, stool tagging quality was high (mean 3.7–4.5) and not significantly different among regimens. The HU of layered tagged fluid was higher for regimens C/D than A/B (P = 0.002). Detection of cancer (n = 2), polyps ≥6 mm (n = 21), and ≤5 mm (n = 72) was 100, 81 and 32% respectively, with only four false positives ≥6 mm. Reduced preparation was tolerated better than full endoscopic preparation by 61%. Reduced-laxative CTC with three doses of 20 ml 40% barium sulphate is as effective as more complex regimens, retaining adequate diagnostic accuracy.     

Validation and absolute quantification of MR perfusion compared with CT perfusion in patients with unilateral cerebral arterial stenosis

Objective

The aim of the study was to assess absolute quantification of dynamic susceptibility contrast-enhanced magnetic resonance perfusion (MRP) comparing with computed tomography perfusion (CTP) in patients with unilateral stenosis.

Materials and methods

We retrospectively post-processed MRP in 20 patients with unilateral occlusion or stenosis of >79% at the internal carotid artery or the middle cerebral artery (MCA). Absolute quantification of MRP was performed after applying the following techniques: cerebrospinal fluid removal, vessel removal, and automatic segmentation of brain to calculate the scaling factors to convert relative cerebral blood volume (rCBV) and relative cerebral blood flow (rCBF) values to absolute values. For comparison between MRP and CTP, we manually deposited regions of interest in bilateral MCA territories at the level containing the body of the lateral ventricle.

Results

The correlation between MRP and CTP was best for mean transit time (MTT) (r = 0.83), followed by cerebral blood flow (CBF) (r = 0.52) and cerebral blood volume (CBV) (r = 0.43). There was no significant difference between CTP and MRP for CBV, CBF, and MTT on the lesion side, the contralateral side, the lesion-contralateral differences, or the lesion-to-contralateral ratios (P > 0.05). The mean differences between MRP and CTP were as follows: CBV −0.57 mL/100 g, CBF 2.50 mL/100 g/min, and MTT −0.90 s.

Conclusion

Absolute quantification of MRP is possible. Using the proposed method, measured values of MRP and CTP had acceptable linear correlation and quantitative agreement.     

Yield of head CT in the alcohol-intoxicated patient in the emergency department

We aimed to determine the yield of positive head computed tomography (CT) findings among suspected alcohol-intoxicated patients presenting to the emergency department (ED). Our secondary aim was to determine if elderly intoxicated patients were more likely to have an intracranial injury. We identified patients suspected of alcohol intoxication who underwent CT scanning in the ED over a 4-year period. Pre-determined data elements including demographics, diagnosis, and disposition were extracted using a pre-formatted data sheet by blinded abstractors. “Positive” CT was defined as evidence of any type of intracranial hemorrhage. A total of 2,671 subjects with suspected alcohol intoxication and a head CT were identified. Fifty out of the 2,671 (1.9%) had a positive CT. Among CT scans of elderly (≥60 years of age) subjects, 15/555 (2.7%, 95% CI = 1.4–4.1%) were positive compared with 35/2,116 (1.7%, 95% CI = 1.1–2.2%) among those <60 years of age (p = 0.11). The yield of positive head CT among alcohol-intoxicated patients was low, at 1.9%. An age cutoff of 60 years in this population did not predict a significantly higher positive rate.     

Perfusion CT in acute stroke: prediction of vessel recanalization and clinical outcome in intravenous thrombolytic therapy

This study evaluated perfusion computed tomography (PCT) for the prediction of vessel recanalization and clinical outcome in patients undergoing intravenous thrombolysis. Thirty-nine patients with acute ischemic stroke of the middle cerebral artery territory underwent intravenous thrombolysis within 3 h of symptom onset. They all had non-enhanced CT (NECT), PCT, and CT angiography (CTA) before treatment. The Alberta Stroke Program Early Computed Tomography (ASPECT) score was applied to NECT and PCT maps to assess the extent of ischemia. CTA was assessed for the site of vessel occlusion. The National Institute of Health Stroke Scale (NIHSS) score was used for initial clinical assessment. Three-month clinical outcome was assessed using the modified Rankin scale. Vessel recanalization was determined by follow-up ultrasound. Of the PCT maps, a cerebral blood volume (CBV) ASPECT score of >6 versus ≤6 was the best predictor for clinical outcome (odds ratio, 31.43; 95% confidence interval, 3.41–289.58; P < 0.002), and was superior to NIHSS, NECT and CTA. No significant differences in ASPECT scores were found for the prediction of vessel recanalization. ASPECT score applied to PCT maps in acute stroke patients predicts the clinical outcome of intravenous thrombolysis and is superior to both early NECT and clinical parameters. S.P. Kloska and R. Dittrich contributed equally to this work.     

Dose reduction in dynamic perfusion CT of the brain: effects of the scan frequency on measurements of cerebral blood flow, cerebral blood volume, and mean transit time

The influence of the frequency of computed tomography (CT) image acquistion on the diagnostic quality of dynamic perfusion CT (PCT) studies of the brain was investigated. Eight patients with clinically suspected acute ischemia of one hemisphere underwent PCT, performed on average 3.4 h after the onset of symptoms. Sixty consecutive images per slice were obtained with individual CT images obtained at a temporal resolution of two images per second. Eight additional data sets were reconstructed with temporal resolutions ranging from one image per second to one image per 5 s. Cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) measurements were performed in identical regions of interest. Two neuroradiologists evaluated the PCT images visually to identify areas of abnormal perfusion. Perfusion images created up to a temporal resolution of one image per 3 s were rated to be diagnostically equal to the original data. Even at one image per 4 s, all areas of infarction were identified. Quantitative differences of CBF, CBV and MTT measurements were ≤10% up to one image per 3 s. For PCT of the brain, temporal resolution can be reduced to one image per 3 s without significant compromise in image quality. This significantly reduces the radiation dose of the patient.     

Whole-brain CT perfusion: reliability and reproducibility of volumetric perfusion deficit assessment in patients with acute ischemic stroke

Introduction

The aim of this study was to examine reliability and reproducibility of volumetric perfusion deficit assessment in patients with acute ischemic stroke who underwent recently introduced whole-brain CT perfusion (WB-CTP).

Methods

Twenty-five consecutive patients underwent 128-row WB-CTP with extended scan coverage of 100 mm in the z-axis using adaptive spiral scanning technique. Volumetric analysis of cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), time to peak (TTP), and time to drain (TTD) was performed twice by two blinded and experienced readers using OsiriX V.4.0 imaging software. Interreader agreement and intrareader agreement were assessed by intraclass correlation coefficients (ICCs) and Bland–Altman Analysis.

Results

Interreader agreement was highest for TTD (ICC 0.982), followed by MTT (0.976), CBF (0.955), CBV (0.933), and TTP (0.865). Intrareader agreement was also highest for TTD (ICC 0.993), followed by MTT (0.988), CBF (0.981), CBV (9.953), and TTP (0.927). The perfusion deficits showed the highest absolute volumes in the time-related parametric maps TTD (mean volume 121.4 ml), TTP (120.0 ml), and MTT (112.6 ml) and did not differ significantly within this group (each with p?>?0.05). In comparison to time-related maps, the mean CBF perfusion deficit volume was significantly smaller (92.1 ml, each with p?<?0.05). The mean CBV lesion size was 23.4 ml.

Conclusions

Volumetric assessment in WB-CTP is reliable and reproducible. It might serve for a more accurate assessment of stroke outcome prognosis and definition of flow-volume mismatch. Time to drain showed the highest agreement and therefore might be an interesting parameter to define tissue at risk.     

Utility of CT perfusion with 64-row multi-detector CT for acute ischemic brain stroke

We investigated the utility of computed tomographic (CT) perfusion (CTP) with 64-row multi-detector row CT (MDCT) to diagnose acute infarction and ischemic penumbra. We reviewed 58 clinical cases with acute ischemic stroke with CTP, compared the size of the area with long mean transit time (MTT) to that with abnormal intensity in magnetic resonance (MR) diffusion-weighted imaging (DWI) to diagnose penumbra, and compared the size of the area with reduced cerebral blood volume (CBV) in CTP to that in MR DWI to evaluate sensitivity for infarction. The total sensitivity of MTT to acute ischemic lesions was 81% (47/58). Sensitivity of MTT to segmental lesions was 100% (42/42) and for spot and focal lesions, 31% (5/16). In 13 patients, penumbra was diagnosed as lesions mismatched between MTT in CTP and MR DWI. When we regarded a lesion with decreased CBV as infarction, the sensitivity of CBV to segmental lesions was 85% (11/13), and the sensitivity to small infarction was 14% (4/28). Use of 64-row MDCT improves coverage and radiation exposure in head CTP. The combination of plain CT, CT angiography, and CTP with MDCT can demonstrate all segmental ischemic lesions and most large segmental infarctions, and their combined application is useful in considering indication and contraindication for thrombolysis. The problem of low sensitivity for small lesions remains, and MR DWI may be required to assess small infarctions when findings from combined plain CT, CT angiography, and CTP are negative in patients with suspected acute brain stroke.     

Can perfusion CT assessment of primary colorectal adenocarcinoma blood flow at staging predict for subsequent metastatic disease? A pilot study

We aimed to determine whether perfusion CT measurements at colorectal cancer staging may predict for subsequent metastatic relapse. Fifty two prospective patients underwent perfusion CT at staging to estimate tumour blood flow, blood volume, mean transit time, and permeability surface area product. Patients considered metastasis free and suitable for surgery underwent curative resection subsequently. At final analysis, a median of 48.6 months post-surgery, patients were divided into those who remained disease free, and those with subsequent metastases. Vascular parameters for these two groups were compared using t-testing, and receiver operator curve analysis was performed to determine the sensitivity and specificity of these vascular parameters for predicting metastases. Thirty seven (71%) patients underwent curative surgery; data were available for 35: 26 (74%) remained disease free; 9 (26%) recurred (8 metastatic, 1 local). Tumour blood flow differed significantly between disease-free and metastatic patients (76.0 versus 45.7 ml/min/100 g tissue; p = 0.008). With blood flow <64 ml/min/100 g tissue, sensitivity and specificity (95% CI) for development of metastases were 100% (60–100%) and 73% (53–87%), respectively. Our preliminary findings suggest that primary tumour blood flow might potentially be a useful predictor warranting further study.     

Combined CT and fluoroscopic guidance of balloon kyphoplasty versus fluoroscopy-only procedures

Objective  To evaluate the performance of combined (computed tomography (CT) and fluoroscopic) guidance of balloon kyphoplasty in comparison to fluoroscopic guidance alone. Materials and methods  Forty-one kyphoplasties were performed between January 2005 and March 2006 according to two different protocols. Study group 1 consisted of 20 consecutive patients with 20 balloon kyphoplasty procedures under dual guidance (CT scan and fluoroscopy) for osteoporotic or traumatic vertebral fractures. Study group 2 consisted of 21 consecutive patients in whom kyphoplasty was performed with fluoroscopy alone. Visualization of the pedicles, the final of the balloon position, and cement distribution were evaluated(1—poor, 2—intermediate, 3—good). Results  Combined use of CT and fluoroscopy (group 1) was superior in identifying the pedicles (100% versus 66.7%, p = 0.009) and balloon placement (100% versus 71.4%, p = 0.02) but not in monitoring of cement distribution within the vertebral body (100% versus 90.5%, p = 0.49). The difference between the two groups was more pronounced in the thoracic spine than in the lumbar spine. Conclusion  CT/fluoroscopic guidance of kyphoplasty combines safe CT-guided insertion of the osteointroducers and balloons as well as fluoroscopic real-time monitoring of polymethylmethacrylate injection.     

Accuracy of whole-body low-dose multidetector CT (WBLDCT) versus skeletal survey in the detection of myelomatous lesions,and correlation of disease distribution with whole-body MRI (WBMRI)

Aim  The aim of the study is to assess the feasibility of whole-body low-dose computed tomography (WBLDCT) in the diagnosis and staging of multiple myeloma and compare to skeletal survey (SS), using bone marrow biopsy and whole-body magnetic resonance imaging (WBMRI; where available) as gold standard. Materials and methods  Patients referred over an 18-month period for investigation of suspected multiple myeloma or restaging of myeloma were randomized to undergo one of two WBLDCT protocols using high kVp, low mAs technique (140 kVp, 14 mAs; or 140 kVp, 25 mAs). Recent WBMRI scans were reviewed in 23 cases. Each imaging modality was assessed by two radiologists in consensus and scored from 0–3 (0 = normal, 1 = 1–4 lesions, 2 = 5–20 lesions, 3 ≥ 20 lesions/diffuse disease) in ten anatomical areas. Overall stage of disease, image quality score, and the degree of confidence of diagnosis were recorded. Diagnostic accuracy of skeletal survey and WBLDCT were determined using a gold standard of bone marrow biopsy and distribution of disease was compared to WBMRI. Results  Thirty-nine patients were evaluated. WBLDCT identified more osteolytic lesions than skeletal survey with a greater degree of diagnostic confidence and led to restaging in 18 instances (16 upstaged, two downstaged). In those with recent WBMRI, distribution of disease on WBLDCT showed superior correlation with WBMRI when compared with SS. Overall reader impression of stage on WBLDCT showed significant correlation with WBMRI (κ = 0.454, p < 0.05). WBLDCT provided complementary information to WBMRI in nine patients with normal marrow signal following treatment response, but which were shown to have diffuse residual cortical abnormalities on CT. Conclusion  WBLDCT at effective doses lower than previously reported, is superior to SS at detecting osteolytic lesions and at determining overall stage of multiple myeloma, and provides complementary information to WBMRI.     

Clinical and radiological outcomes of acute ischemic stroke patients without angiographic occlusion on digital subtraction angiogram. A pooled analysis of case series

Introduction  Approximately 20–30% of the patients with acute ischemic stroke do not have any occlusion demonstrated on initial digital subtraction angiography (DSA). We sought to determine the risk and rates of cerebral infarction and favorable neurological outcome in this group of acute ischemic stroke patients. Materials and methods  Patients were identified from a prospectively maintained stroke database and from literature search of MEDLINE, PubMed, and Cochrane databases. All patients had initial neurological assessment on National Institutes of Health Stroke Scale (NIHSS). Patients then underwent DSA after initial head computed tomography (CT) scans. Follow-up radiological assessment at 24–72 h was performed with CT and magnetic resonance imaging scans. Association of stroke risk factors with clinical and radiological outcomes was estimated. Results  A total of 81 patients was analyzed (mean age 63 years; 28 were women). The median NIHSS score was 8 (range 2–25). None of the patients received either intravenous or intra-arterial thrombolytic. Cerebral infarction was detected in 62 (76%) of the 81 patients. Twenty-four to 48-h NIHSS was available for 51 patients only. Neurological improvement was observed in 22 (43%) of the 51 patients. Favorable outcome ascertained at 3-month follow-up was seen in 48 (59%) of the 81 patients. After adjusting for age, sex, and baseline NIHSS, male patients [odds ratio (OR) 4.5 (1.4–14.3), p value = 0.01] and patients with age ≥65 [OR 4.3 (1.2–16.2), p value = 0.03] have a higher risk of cerebral infarcts on the follow-up imaging. Similarly, patients who presented with <10 NIHSS had a better 3-month outcome than those with >10 NIHSS [OR 0.21 (0.08–0.61), p value = 0.004]. Conclusion  Ischemic stroke patients without arterial occlusion on DSA have a higher risk of cerebral infarction and disability particularly in men, patients over 65 years of age and with NIHSS ≥10. The cause of infarction may have been arterial obstruction with spontaneous recanalization or small vessel occlusion not visible on DSA.     

兔急性闭合性脑挫裂伤后脑血流动态CT灌注成像的实验研究

目的 探讨脑挫裂伤动物模型局部脑血流灌注动态变化规律.方法 40只新西兰大白兔,自由落体法制作闭合性脑挫裂伤模型,外伤后1、3、6、12、24、48及72 h行CT灌注(CTP)检查,源图像传输至工作站进行后处理.选择病变最大层面,测量各时间点脑挫裂伤中央区、周边区及对应镜像区脑血流量(CBF)、脑血容量(CBV)及平均通过时间(MTT).中央区与镜像区、周边区与镜像区CTP各参数进行配对t检验.观察CBF、CBV及MTT演变规律.对照CTP图像,观察脑挫裂伤中央区与周边区病理改变.结果 35只动物建模成功,T_2WI及DWI可见脑挫裂伤局部异常信号.CTP参数变化趋势:(1)外伤各时间点中央区CBF值均显著下降,至12 h降至最低点,24 h开始缓慢增高;1、3、6、12、24、48、72 h时CBF分别为(27.58±18.70)、(20.64±6.50)、(23.38±7.53)、(22.14±10.25)、(25.08±11.01)、(43.08±18.33)、(54.79±14.63)ml·min~(-1)·100 g~(-1),镜像区为(62.28±25.46)、(60.67±16.19)、(67.00±21.34)、(74.46±20.11)、(66.73±11.68)、(81.63±10.99)、(86.16±10.57)ml·min~(-1)·100 g~(-1),外伤区与镜像区各时间点差异有统计学意义(t值分别为4.41、5.57、5.47、6.02、6.44、4.81、10.60,P值均＜0.05);周边区CBF稍减低,1、3 h略明显,此后缓慢增高,与镜像区差异无统计学意义(P值均＞0.05).(2)外伤各时间点中央区CBV值均显著下降,至12 h降至最低点,24 h开始缓慢增高;各时间点中央区CBV分别为(1.74±0.46)、(2.22±0.86)、(2.26±0.44)、(1.15±0.22)、(2.67±0.77)、(2.68±0.72)、(2.86±0.65)ml/100 g,镜像区为(7.27±5.29)、(6.18±1.82)、(6.93±1.86)、(6.66±2.75)、(8.48±2.34)、(8.56±2.38)、(8.83±1.57)ml/100 g,差异有统计学意义(t值分别为3.09、5.38、6.25、4.80、7.82、6.36、8.51,p值均＜0.05);周边区CBV稍减低,1 h与3 h略著,此后缓慢增高,与镜像区差异无统计学意义(P值均＞0.05),上升趋势近似.(3)中央区1～3 h MTT显著延长,3 h后MTT值下降明显,至12 h达到平台期,中央区各时间点MTT分别为(4.88±1.37)、(5.09±1.21)、(4.49±1.33)、(3.44±0.46)、(3.58±0.42)、(3.51±0.73)、(3.30±0.27)s,镜像区为(2.03±0.07)、(2.03±0.04)、(2.04±0.07)、(2.00±0.55)、(2.07±0.20)、(2.06±0.06)、(2.02±0.02)s,各时间点与镜像区差异均有统计学意义(t值分别为5.87、5.95、4.43、7.74、9.02、4.73、4.76,P值均＜0.05).周边区24 h前MTT增加,1～24 h呈逐渐下降趋势,24、72 h时与镜像区差异无统计学意义.镜像区各时间点MTT变化不明显.病理学上中央区出血、坏死、水肿及血管周围间隙增大均较周边区明显.结论 CTP能敏感地发现及监测兔脑挫裂伤后血流动力学变化,脑挫裂伤区血流灌注变化有一定的时间规律,且病变中央区变化较周边区明显.     

Reproducibility of quantitative CT brain perfusion measurements in patients with symptomatic unilateral carotid artery stenosis

BACKGROUND AND PURPOSE: To establish intraobserver and interobserver variability for regional measurement of CT brain perfusion (CTP) and to determine whether reproducibility can be improved by calculating perfusion ratios. MATERIALS AND METHODS: CTP images were acquired in 20 patients with unilateral symptomatic carotid artery stenosis (CAS). We manually drew regions of interest (ROIs) in the cortical flow territories of the anterior (ACA), middle (MCA), and posterior (PCA) cerebral arteries and the basal ganglia in each hemisphere; recorded cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT); and calculated ratios of perfusion values between symptomatic and asymptomatic hemisphere. We assessed intraobserver and interobserver variability by performing a Bland-Altman analysis of the relative differences between 2 observations and calculated SDs of relative differences (SDD(rel)) as a measure of reproducibility. We used an F test to assess significance of differences between SDD(rel) of absolute CTP values and CTP ratios, and the Levine test to compare the 4 perfusion territories. RESULTS: MTT was the most reproducible parameter (SDD(rel) 相似文献   

Comparison of MRI (including SS SE-EPI and SPIO-enhanced MRI) and FDG-PET/CT for the detection of colorectal liver metastases

Fluoro-18-deoxyglucose positron emission tomography computed tomography (FDG-PET/CT) and magnetic resonance imaging (MRI), including unenhanced single-shot spin-echo echo planar imaging (SS SE-EPI) and small paramagnetic iron oxide (SPIO) enhancement, were compared prospectively for detecting colorectal liver metastases. Twenty-four consecutive patients suspected for metastases underwent MRI and FDG-PET/CT. Fourteen patients (58%) had previously received chemotherapy, including seven patients whose chemotherapy was still continuing to within 1 month of the PET/CT study. The mean interval between PET/CT and MRI was 10.2 ± 5.2 days. Histopathology (n = 18) or follow-up imaging (n = 6) were used as reference. Seventy-seven metastases were detected. In nine patients, MRI and PET/CT gave concordant results. Sensitivities for unenhanced SS SE-EPI, MRI without SS SE-EPI and FDG-PET/CT were, respectively, 100% (p = 9 × 10⁻¹⁰ vs PET, p = 8 × 10⁻³ vs MRI without SS SE-EPI), 90% (p = 2 × 10⁻⁷ vs PET) and 60%. PET/CT sensitivity dropped significantly with decreasing size, from 100% in lesions larger than 20 mm (identical to MRI), over 54% in lesions between 10 and 20 mm (p = 3 × 10⁵ versus unenhanced SS SE-EPI), to 32% in lesions under 10 mm (p = 6 × 10⁻⁵ versus unenhanced SS SE-EPI). Positive predictive value of PET was 100% (identical to MRI). MRI, particularly unenhanced SS SE-EPI, has good sensitivity and positive predictive value for detecting liver metastases from colorectal carcinoma. Its sensitivity is better than that of FDG-PET/CT, especially for small lesions.