APPROPRIATE USE OF MYOCARDIAL PERFUSION IMAGING IN A VETERAN POPULATION
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Background: Transient ischemic attacks (TIA) are cerebral ischemic events without infarction. The uses of CT perfusion (CTP) techniques such as cerebral blood volume (CBV), time to peak (TTP), mean transit time (MTT) and cerebral blood flow (CBF) provide real time data about ischemia. It has been shown that CTP changes occur in less sensitive CTP scanners in patients with TIA. Larger detector row CTP (whole brain perfusion studies) may show that CTP abnormalities are more prevalent than previously noted. It is also unclear if these changes are associated with TIA severity. Objective: To demonstrate that TIA patients are associated with perfusion deficits using whole brain 320-detector-row CT perfusion, and to determine an association between ABCD2 score and perfusion deficit using whole brain perfusion. Methods: We retrospectively reviewed all TIA patients for CTP deficits from 2008–2010. Perfusion imaging was reviewed at admission; and it was determined if a perfusion deficit was present along with vascular territory involved. Results: Of 364 TIA patients, 62 patients had CTP deficits. The largest group of patients had MCA territory involved with 48 of 62 patients (77.42%). The most common perfusion abnormality was increased TTP with 46 patients (74.19%). The ABCD2 score was reviewed in association with perfusion deficit. Increased age >60, severe hypertension (>180/100 mmHg), patients with speech abnormalities, and duration of symptoms >10 min were associated with a perfusion deficit but history of diabetes or minimal/moderate hypertension (140/90–179/99 mmHg) was not. There was no association between motor deficit and perfusion abnormality. Conclusion: Perfusion deficits are found in TIA patients using whole brain CTP and associated with components of the ABCD2 score.
Stroke
Abnormality
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Renal cortex
Renal medulla
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Objective To evaluate the MR perfusion imaging in measuring the hemodynamics of liver.Methods CT and MR perfusion imaging were performed in livers of 13 pigs.The hepatic artery perfusion(HAP),portal vein perfusion(PVP),total hepatic blood flow(THBF),portal vein perfusion index(PVI),distribution volume(DV)and mean transit time(MTT)were calculated and compared respectively.Hemodynamics of the liver from two kinds of imaging was compared by paked t-test,and the relativity was analyzed by Pearson correlation analysis.Results In CT and MR perfusion imaging of the 13 pigs:the hepatic artery perfusion(HAP)were(37.7±7.38)and(35.80±7.31)ml-min-1·100ml-1.the portal vein perfusion(PVP)were(123.16 35.89)and(121.40±36.81)ml·min-1·100 ml-1.the total hepatic blood flow(THBF)were(160.88±37.05)and(157.21±38.71)ml·min-1·100 ml-1.the portal vein perfusion index(PVI)were(75.95±5.21)%and(76.63±5.24)%,the distilbution volume(DV)were(35.10±11.17)%and(41.03±10.06)%。The mean transit time(MTT)were(14.08±1.40)and(14.94±1.32)s.There were no statistical differences for HAP,PVP,THBF and PVI between CT and MR perfusion imaging(t=1.263,0.926,1.225,-1.115,P＞0.05).There were no statistical differences for DV and MTT(t=-3.345,-3.200,P＜0.01).Analysis of these two kinds of imaging showed the correlation coefficient of PVP,THBF and PVI were hishly related(r＞0.85,P＜0.01).Correlation coefficient of HAP,DV and M1T were moderately related(r＞0.70,P＜0.01).Conclusions MR perfusion Call quantify the blood flow parameters of liver accurately.It is close to that of the CT perfusion imaging.
Key words:
Magnetic resonance imaging; Tomography,X-ray computed; Liver
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Objective To evaluate the diagnostic value of CT perfusion in cerebral ischemic infarction. Methods First pass,single section perfusion CT was performed in 15 patients who presented with symptoms of acute stroke onset between 5 and 20 hours. Single section perfusion CT scans were obtained immediately after the nonenhanced CT study in interested section. Results For 4/15 cases, ischemic lesions were found on both conventional CT and CT perfusion image after 12 hours onset of stroke,6/15 patients had negative results on conventional CT less 12 hours but positive on CT perfusion, three parametric images showed the lesions hypoperfusion,the lesions itself showed MTT delay,CBF and CBV decrease. 5/15 cases had negative results on both conventional CT and CT perfusion. Conclusion Perfusion CT is potentially useful for detecting cerebral perfusion deficits in acute ischemic stroke before morphologic changes are observable on native CT scans.
Stroke
Acute stroke
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Perfusion computed tomography (CT) allows to evaluate brain perfusion and provides additional information about local cerebral hemodynamics in stroke patients. Twenty-seven patients underwent CT-perfusion in the early acute phase of ischemic stroke. Significant differences between ischemic lesion and contralateral hemisphere on CBF and MTT scans during the first 3 hours after stroke were revealed. In the following 24 h, the differences were seen in all perfusion parameters. CT-perfusion allows to reveal perfusion parameters associated with stroke severity and outcome that is relevant for prescription of reperfusion treatment beyond the boundaries of 3-4.5h "therapeutic window".
Stroke
Acute stroke
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Perfusion is a fundamental biological function, giving an indication of tissue metabolism, through the rate of blood supply. Changes in perfusion accompany almost all forms of brain disease giving a wide range of potential applications for perfusion imaging. Arterial spin labelled MRI, the subject of this thesis, is a good method of measuring brain perfusion. Issues of perfusion quantification, i.e. accuracy and precision are addressed. Current models of the perfusing system assume that water is freely diffusible across the capillary wall. Several published values show that this is not true in the brain where the blood brain barrier restricts water passage. A corrected two-compartment model is presented, with simplifications for use in vivo. Simulations show that the change to perfusion estimation is large. In vivo modelling shows an improved fit for all extremes of perfusion. Perfusion reproducibility is measured for different tissue volumes and is found to compare favourably with other perfusion techniques. A study of thirty-two normal volunteers shows that inter-subject perfusion variation is large, but perfusion within a single subject remains fairly stable over the course of a day and a week. A significant (p<0.05) negative correlation of grey matter perfusion with age is reported, giving a perfusion decrease of 0.5% per year. Female whole brain perfusion is found to be 16% higher than in males (p=0.02). Measurements of perfusion change are made in stroke, arteriovenous malformation (AVM), motor activation and multiple sclerosis. The examples in stroke and motor activation serve as important validation of the technique and the modelling. Gross perfusion abnormalities are detected in AVM showing different perfusion characteristics in different regions of AVM. More subtle changes are found in multiple sclerosis, with significant perfusion increases in the normal appearing white matter compared to normal controls.
Stroke
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Objective To evaluate the feasibility of 320-row volume CT myocardial perfusion imaging (CT-MPI) in detecting myocardial perfusion defect.Methods Fourteen patients with positive single-positron emission computed tomography myocardial perfusion imaging (SPECT-MPI) findings underwent both rest and adenosine stress 320-row volume CT-MPI.Rest and stress CT perfusion images were analyzed by employing dedicated software in 320-row CT workstation.Both SPECT-MPI and CT-MPI were evaluated for fixed and reversible perfusion defects using a 16-segment model (apex was excluded).The sensitivity,specificity of 320-row volume CT-MPI in detecting myocardial perfusion defect were evaluated by taking SPECT-MPI as a reference standard.Results Both rest and stress 320-row volume CT-MPI were successfully performed in all patients.Thirty nine segments with fixed or reversible perfusion defects in all patients were depicted by SPECT-MPI,while 34 perfusion defects in 12 patients were identified by CT-MPI.The sensitivity,specificity of 320-row volume CT-MPI for detection of perfusion defects were 87.2％(34/39),91.4％ ( 169/185 ),respectively.Conclusion 320-row volume CT-MPI has high sensitivity and specificity for detection of myocardial perfusion defects.
Key words:
Coronary disease; Tomography, X-ray computed; Myocardium; Perfusion
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While CT coronary angiography (CTCA) is gaining acceptance as a diagnostic technique, MDCT derived myocardial perfusion has not been validated against an accepted reference standard. We sought to develop a technique for quantitative assessment of myocardial perfusion from MDCT images, and investigate the diagnostic value of resting MDCT perfusion in comparison with SPECT myocardial perfusion imaging (MPI). We studied 98 consecutive patients undergoing CTCA who also had MPI. 20 patients with normal MPI were used as controls. MDCT perfusion was measured in 16 segments in terms of x-ray attenuation. Abnormal resting perfusion was detected by comparison against normal values obtained in the control group. Accuracy of detection was determined against resting MPI on a segment, vascular territory and patient basis. To determine the causes of resting perfusion defects detected by MDCT but not confirmed by resting MPI, stress MPI data were used. Perfusion abnormalities were detected by resting MPI in 36/78 patients in 58 vascular territories. MDCT detected these abnormalities in 31/36 patients (sensitivity 0.86). Abnormalities found in additional 28/78 patients were not confirmed by resting MPI (specificity 0.33). However, 23 of these 28 apparently false positive resting MDCT perfusion tests (82%) were associated with abnormal stress MPI. In the majority of these 23 patients (16 or 70%), the quality of MDCT images was optimal, while in the remaining 5/28 patients with resting MDCT perfusion abnormalities that were not confirmed by stress MPI, 4 (80%) had suboptimal images. Resting MDCT can accurately detect perfusion abnormalities in agreement with resting MPI. Moreover, the majority of abnormalities not confirmed by resting MPI were associated with stress-induced ischemia. Therefore, myocardial perfusion assessment, even at rest, is a potentially valuable addition to MDCT tools for noninvasive evaluation of coronary artery disease without additional radiation or contrast load, which promises not only to improve the diagnostic accuracy of cardiac CT, but is also likely to prove as a cost-effective, single-stop alternative to costly serial testing.
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In this study, we compared contrast-enhanced ultrasound perfusion imaging with magnetic resonance perfusion-weighted imaging or perfusion computed tomography for detecting normo-, hypo-, and nonperfused brain areas in acute middle cerebral artery stroke. We performed high mechanical index contrast-enhanced ultrasound perfusion imaging in 30 patients. Time-to-peak intensity of 10 ischemic regions of interests was compared to four standardized nonischemic regions of interests of the same patient. A time-to-peak >3 s (ultrasound perfusion imaging) or >4 s (perfusion computed tomography and magnetic resonance perfusion) defined hypoperfusion. In 16 patients, 98 of 160 ultrasound perfusion imaging regions of interests of the ischemic hemisphere were classified as normal, and 52 as hypoperfused or nonperfused. Ten regions of interests were excluded due to artifacts. There was a significant correlation of the ultrasound perfusion imaging and magnetic resonance perfusion or perfusion computed tomography (Pearson's chi-squared test 79.119, p < 0.001) (OR 0.1065, 95% CI 0.06-0.18). No perfusion in ultrasound perfusion imaging (18 regions of interests) correlated highly with diffusion restriction on magnetic resonance imaging (Pearson's chi-squared test 42.307, p < 0.001). Analysis of receiver operating characteristics proved a high sensitivity of ultrasound perfusion imaging in the diagnosis of hypoperfused area under the curve, (AUC = 0.917; p < 0.001) and nonperfused (AUC = 0.830; p < 0.001) tissue in comparison with perfusion computed tomography and magnetic resonance perfusion. We present a proof of concept in determining normo-, hypo-, and nonperfused tissue in acute stroke by advanced contrast-enhanced ultrasound perfusion imaging.
Contrast-enhanced ultrasound
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Objective:To discuss the technique and clinical significance of Multislice spiral computed tomography(MSCT) tumor perfusion imaging.Method:Eleven tumor patients were examined by MSCT perfusion imaging.The tumor centers were ascertained by routine CT firstly followed by perfusion scanning.Tumor centers were scanned by film scanning technique(1 r/0.75s).Every slice was 0.6 mm and 50ml contrast material was injected at a flow rate of 5 ml/s.The contrast material injecting and CT scanning were done simultaneously.Total scan time was 40 secs.Images analysis and perfusion parameter were processed and calculated by workstation,including the volume of arterial perfusion(AP or Art.Perf.),vein perfusion(PP or Port Perf.),total perfusion(TP or Total Perf.) and hepatic perfusion index(HPI).Results:All tumors' size and outline were showed clearly and perfusion parameter increased greatly.Perfusion state in the inside of tumor could be quantified detected.The images were limpid with high resolution ratio.Conclusion:MSCT perfusion imaging is an accurate,quick and simple method to quantified estimate bloodstream perfusion state of tumors.
Multislice
Arterial perfusion
Spiral computed tomography
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