發(fā)育性靜脈異常 灌注

1、Developmental venous anomalies: appearance on whole-brain CT digital subtraction angiography and CT perfusion AbstractIntroduction Developmental venous anomalies (DVA) consist of dilated intramedullary veins that converge into a large collecting vein. The appearance of these anomalies was evaluated

2、on whole-brain computed tomography (CT) digital subtraction angiography (DSA) and CT perfusion(CTP) studies.Methods CT 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 abnorma

3、lities. CT angiograms, CT arterial venousviews, 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 (MT

4、T), 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

5、 of 2%, 10%, and 9% for CBF, CBV, and MTT, respectively. Average effective radiation dose was 4.4 mSv.Conclusion Whole-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 ce

6、rebellum. Future research may identify the rare subsets of patients at increased risk of adverse outcomes secondary to the alteredhemodynamics to facilitate tailored imaging surveillance and application of appropriate preventive therapeutic measures. Keywords Computed tomography . CT angiography . C

7、T perfusion . Developmental venous anomalies . DiscussionThis study demonstrates that CTP may permit assessment of the hemodynamic alterations associated with DVA. For each DVA in this study, absolute CBV and CBF values were significantly increased in the affected hemisphere as compared to the unaff

8、ected hemisphere. On MR perfusion, Camacho et al. 12 also identified increased CBF, CBV, and MTT in four uncomplicated DVA cases. The authorsconcluded that hemodynamic alterations were not associated with the presenting symptoms of the patients and that the alterations did not imply a more ominous f

9、uture outcome for the DVA. The results of this study suggested thatincreased regional CBV and CBF on CTP may indicate the presence of a DVA on CTP of the brain and case 1 presented with facial numbness symptoms that may have been influenced by the presence of the DVA. Previous studies have identifie

10、d decreased CBF values in the parenchyma near two large DVA on xenon-enhanced CT 21 and in one patient on brain perfusion SPECT that the authors believed was correlated with the SPECT abnormalities, DVA location, and an electroencephalograph focus 22. However, differentiation of the intravascularhem

11、odynamic changes and the surrounding parenchymal perfusion changes using the ROI approach in this study is limited due to the averaging of the CTP values within the ROI and future studies using a pixel-by-pixel evaluation of the DVA and the surrounding parenchyma could provide an answer. Although MT

12、T was consistently elevated and suggestive of delayed or slow flow in this small group of five patients, further study is required to determine how the whole-brain hemodynamic (i.e., CBV and CBF) and temporal CTP values (i.e., MTT, TTP, and delay) within the DVA can be utilized to further delineate

13、the hemodynamic parameters for a larger collection of DVA cases. Because MTT is an indicator of perfusion pressure, the higher MTT values in the DVA indicated lower flow or perfusion and increased MTT values have previously been associated with DVA infour patients on MR perfusion 12. The unaffected

14、hemispheres of each case appeared to be influencing the relative percentage change in MTT values, but because of insignificant p values and the small sample size, evaluation of trends in MTT values in patients with a DVA over time will require further research. TTP results for DVA cases must be inte

15、rpreted in the context of each individual patient. TTP was not indicative of DVA in this study. This was possibly due to the widerange of DVA types that can both increase and decrease the time for blood to get to a region. TTP is a temporal parameter that can be falsely prolonged depending ontechnic

16、al factors of the scanning process and by the size and shape of the arterial input function. Cases 1, 3, and 4 had higher relative TTPs in the affected hemisphere (range 1.99-6.45%) that suggested slower arrival of contrast to theDVA. This may be anticipated in slow flow venous structures with lower

17、 proportions of arterial influence on TTP values. For cases 2 and 5, rapid flow and lower relative TTP (4.09% in case 5 to 7.43% in case 2) in the affected hemisphere could be interpreted as contribution from a possible arteriovenous shunting component but this could not be confirmed and no arterial

18、 abnormalities were noted on CT DSA for cases 2 and 5. Further DVA case analyses will be required to evaluate if TTP may serve as a stratifier for CTP pressures in DVA and a possible CTP parameter that may, in combination with the CBV, CBF, and MTT results, help to delineate an individuals risk of f

19、uture complications. Flow-related complications of DVA that may lead to a symptomatic presentation include an increase of inflow because of an arteriovenous shunt, a decrease of outflow, ora remote shunt with increased venous pressure 10. In our study, case 1 presented with symptoms that was possibl

20、y secondary to a DVA (Fig. 5). Pereira et al. Suggested characteristics of an increased risk of symptomatic DVA presentation: large and complex DVA with changes on MRI suggesting venous congestion, acute or subacute ischemic changes, asymmetrical medullary zone appearance, and association with AVMs

21、10. Mechanical compression of intracranial structures around the DVA produced symptoms in 20.3% (14 of 69 cases). Unexplained symptomatology occurred in 8.7% (six of 69 cases) while the remaining 71% (49 of 69 cases) of symptomatic DVA were attributed to flow-related pathomechanisms (19 with increas

22、ed inflow, 26 with decreased outflow, and four with a shunt thatincreased venous pressure) 10. The findings of the present study suggest that anatomical variations in DVA that can influence hemodynamic flow may be characterized by the combination of assessment by CTA-V (Fig. 4d), wholebraindynamic v

23、olume CTP, and 4D DSA. As reviewed by Hammoud et al. 13, nonhemorrhagic ischemia associated with DVA is uncommon and rarely reported in the literature. A review by Hon et al. 23 of 15 studies that included 714 patients with DVA found that less than 1% were associated with infarction on the initialpr

24、esentation. The etiology of nonhemorrhagic infarcts associated with DVA has been proposed as thrombosis of the collecting or draining vein 13 and has been identified on angiography 24. Stenosis at the dural opening of DVA is also frequently noted and this has been proposed as a mechanism for initiat

25、ing a DVA thrombosis 4, 25. In this study, no case had clinically discernible stenosis, but case 3 had multiple terminal draining veins that lead into a small dural opening (Fig. 4a, d). DVA that demonstrate thrombotic complications are treated the same as cortical venous or venous sinus thromboses.

26、 An identical laboratory workup is required and consideration for treatment with anticoagulation is appropriate. Investigation of procoagulating factors or prothrombotic conditions is also important 10. Regardless of the treatment method implemented, it is important that the integrity of the DVA be

27、preserved to avoid the substantial neurologic complications previously documented when it is excised either inadvertently or dueto clinical necessity 10, 13, 26. DVA-associated hemorrhagic and nonhemorrhagic infarctions are rare, but implementation of prevention measures upon identification, such as

28、 hydration in warm climates, smoking cessation, or anticoagulant medications for individuals at increased risk of thrombosis as indicated may reduce risk of adverse events. Although DVA complications are rare, the complications of DVA are more frequently hemorrhagic than ischemic innature 25, 27, 28

29、. The Hon et al. 23 review found that 6% with DVA presented with symptomatic hemorrhage and the hemorrhage rate following the first event was 0-1.28% per year for 422 of these 714 patients. In a prospective study by the same authors on 93 adults, one patient presented with symptomatic hemorrhage and

30、 there were no symptomatic hemorrhages following the first presentation for a total of 492 person-years of follow-up 23. Formation of a thrombus within a DVA has also been proposed as a cause of DVA-associated hemorrhage secondary to increased venous pressure 27. Additionally, DVA hemorrhages may no

31、t result from the DVA itself but may be associated with co-occurring or developing anomalies including CM, capillary telangiectasias, and AVMs. Hemorrhage of DVA with an associated CM has been welldocumented 1, 7, 9, 16, 29, 30 and Hong et al. 14 described angioarchitectural factors of DVA that may

32、cause concurrent sporadic CM to form. Further evaluation is required to determine if DVA progression to capillary telangiectasias and CMs or AVM proximity to DVAs can belongitudinally monitored with CTP. Previous CT technology has not allowed whole-brain visualization and as demonstrated in this stu

33、dy, comprehensive DVA analysis requires whole-brain CTP for visualization of the peripheral or superior cerebral cortices (case 1 in Fig. 5; cases 2, 4, and 5) or in the posterior fossa(case 3 in Fig. 4). With the recent scientific advances in understanding of the pathophysiology 10 and angioarchite

34、ctural factors 14 of DVA coupled with the increasing clinical availability of whole-brain CTP, this preliminary study data indicates that the incremental diagnostic information for DVA can be provided by whole-brain CTP studies. Further investigations are required to use CTP as a method for identify

35、ing individuals at greatest risk for adverse clinical outcomes related to DVA. Additionally, it is possible that assessment of the CTP parameters associated with DVA may help to avoid incorrect diagnoses such as arterial infarcts, focal hemorrhage, demyelinating disease 31, neoplasm, or similar appe

36、aring abnormalities on CT 13. Misdiagnosis of DVA and DVA-associated infarcts hasbeen documented and may be secondary to the heterogeneous imaging characteristics of cerebral venous infarctions 32. Additionally, DVA are frequently not identified on other imaging studies including non-contrast CT and

37、structural MRI but may be detected with CTP, as was true of case 5 in this study (Table 1). In order to assess the risk associated with diagnostic procedures, both physical risk and radiation dose must be considered. Due to its interventional nature, conventional angiography has a 0.5% risk of perma

38、nent neurologic complication 33 and a typical effective radiation dose of 10.6 mSv 34. The whole-brain CT imaging protocol used in this study, that included CT DSA and CTP, had an effective dose of 4.3-4.4 mSv (Table 2). Effective radiation dose for 64-slice CTP has been reported as 7.5-11.4 mSv 34.

39、 The whole-brain CTP protocol used in this study islower than conventional angiography or 64-slice CT and is less than one third of the level reported as acceptable by the FDA for brain perfusion imaging 35. As with any imaging study, the benefit of the diagnostic information acquired must always be

40、 weighed versus the radiation risk. There were limitations of this study. CTP value variation using ROIs and placement of the ROIs near vessels or artifacts can adversely impact the clinical interpretation of results. Variation with the 8 mm ROIs was increased for two reasons: (1) a HU densities in

41、the ROI are averaged inthe vicinity of each voxel together and (2) when the ROI is placed in areas with vessels, the flow and volumes are significantly higher. CTP values obtained within the area of the DVA and in the contralateral hemisphere have different compositions of parenchymal and vascular c

42、omponents and this variability could not be quantified. Vascular and tissue differentiation could be improved by pixel-by-pixel CTP value evaluations and this could increase precision in defining the range of CTP values at important DVA structures, such as the terminal vein opening. Additionally, no

43、 cases had angiographical confirmation of associated pathologies. Finally, expanded CTP studies with higher numbers of patients usingstandardized system configurations (e.g., hardware, software, and protocols) with human variables (e.g., estimates of cardiac output and hematocrit) incorporated into

44、the DICOM files may help to facilitate individual CTP analyses, as well as comparisons between individuals. Most DVA are incidental findings on imaging studies and little is known about which individuals will progress to hemorrhagic or ischemic complications. The cases presented suggest that the phy

45、siologic appearance of DVA on CT DSA and whole-brain CTP can provide incremental clinical information to practitioners for diagnostic purposes and with future research may help to provide some of the monitoring and prognostic data required to identify the rare subset of patients with DVA that are at

46、 increased risk of adverse outcomes. 靜脈發(fā)育異常：全腦CT數(shù)字減影血管造影和CT灌注的表現(xiàn)簡介靜脈發(fā)育異常(DVA)由擴(kuò)張的髓內(nèi)靜脈組成，匯合成一個(gè)大收集靜脈。全腦計(jì)算機(jī)斷層掃描（CT）數(shù)字減影血管造影（DSA）和CT灌注（CTP）的研究對(duì)這些異常表現(xiàn)進(jìn)行了評(píng)估。方法對(duì)10例匿名患者的CT數(shù)據(jù)資料進(jìn)行回顧性分析。5例患者具有DVA的證據(jù)，而五例年齡和性別匹配的對(duì)照病例并沒有已知的血管神經(jīng)異常。通過一個(gè)動(dòng)態(tài)容積成像協(xié)議，在320排CT探測(cè)器掃描儀上獲取CT血管造影，CT動(dòng)脈靜脈圖像，4-D CT數(shù)字血管造影和CT灌注圖像。 腦血流量（CBF），腦血容量（CB

47、V）， 達(dá)峰時(shí)間（TTP），平均通過時(shí)間（MTT）和延遲對(duì)全腦CT灌注參數(shù)進(jìn)行評(píng)價(jià)。利用DSA對(duì)DVA解剖可視化。掃描儀控制臺(tái)記錄輻射劑量。結(jié)果CTP值增加出現(xiàn)在DVA的患者中，相對(duì)于未受影響的對(duì)側(cè)半球，CBF，CBV，MTT分別增加48，32，和26; 而對(duì)照組為2，-10和9。平均有效輻射劑量為4.4毫西弗。結(jié)論全腦CTA和CTP成像能顯示的DVA血流動(dòng)力學(xué)參數(shù)變化的特征表現(xiàn)和捕捉大腦和小腦皮質(zhì)的異常。未來的研究可以識(shí)別繼發(fā)于血流動(dòng)力學(xué)改變的不良后果而導(dǎo)致風(fēng)險(xiǎn)增加的患者，以促進(jìn)針對(duì)性成像顯示和適當(dāng)?shù)念A(yù)防治療措施的應(yīng)用。關(guān)鍵詞計(jì)算機(jī)斷層掃描 CT血管造影 CT灌注 靜脈發(fā)育異常 全腦CT灌注

48、 發(fā)育靜脈異常（DVA）表示可與其他腦血管畸形相關(guān)聯(lián)的正常變異。DVA先前已被稱為靜脈血管瘤，靜脈畸形，和髓靜脈畸形1。DVA可位于整個(gè)大腦，并已被描述為近皮層，皮質(zhì)下，或深。深的DVA是通過幕上和幕下位置進(jìn)一步細(xì)分2。宏觀上，DVA已經(jīng)被描述為是漏白且徑向和心地灰質(zhì)成一個(gè)較大的口徑收集或打開成淺表皮層下或深的軟腦膜血管擴(kuò)張薄壁髓質(zhì)血管引流靜脈3,4。DVA代表了近60的腦血管變化（通常歸類為畸形）的尸檢5。在一個(gè)顱磁共振成像（MRI）的8200例患者的調(diào)查，DVA存在于50，提示0.6的時(shí)點(diǎn)患病率6。拋尸的4069箱子研究報(bào)告說，DVA存在于2.57。 DVA是已知與血管有關(guān)的畸形，包括動(dòng)靜

49、脈畸形AVM），海綿狀血管瘤（CM），和毛細(xì)管毛細(xì)血管擴(kuò)張8,9。達(dá)的患者DVA的第三可以具有第二腦血管異常，如CM9。孤立DVA被認(rèn)為是先天的性質(zhì)和一般遵循良性的自然史。然而，對(duì)癥DVA已經(jīng)越來越臨床確定10和神經(jīng)癥狀，如頭痛，抽搐，感覺異常，運(yùn)動(dòng)障礙，三叉神經(jīng)痛，和錐體外系障礙已經(jīng)報(bào)道11。DVA已經(jīng)確定在計(jì)算機(jī)斷層掃描（CT），磁共振成像（MRI），單光子發(fā)射計(jì)算機(jī)斷層顯像（SPECT），常規(guī) 血管造影和數(shù)字減影血管造影（DSA），并可能會(huì)顯示在每個(gè)這些方式的幾個(gè)特征影像學(xué)特征。關(guān)于增強(qiáng)CT，靜脈收集系統(tǒng)的線性或曲線特征是經(jīng)常存在的。在noncontrast MR，DVA可以出現(xiàn)在T1-

50、管狀信號(hào)空隙和T2加權(quán)序列8和可變程度的T1和T2延長可以看出在相鄰的實(shí)質(zhì)12。對(duì)比增強(qiáng)MRI，引流靜脈增強(qiáng) 提供DVA結(jié)構(gòu)的改進(jìn)的可視化。彌散加權(quán)成像，DVA被血栓或梗塞可能顯示為限制擴(kuò)散與區(qū)域 明亮的信號(hào)強(qiáng)度13。磁共振灌注研究已證明增加灌注值12，14。然而，DVA的CT灌注（CTP）參數(shù)只被最近描述15。這可能是繼發(fā)于全腦覆蓋在先前技術(shù)的限制未允許完全可視化在外圍或優(yōu)于大腦皮層在DVA的流動(dòng)相關(guān)的病理機(jī)制的理解的最新進(jìn)展，包括癥狀繼發(fā)于他們的輸入和流出的血流動(dòng)力學(xué)10的風(fēng)險(xiǎn)增加?？梢酝ㄟ^成像檢測(cè)血流動(dòng)力學(xué)的變化，可以通過采集靜脈流出道梗阻，靜脈壁增厚進(jìn)取和結(jié)構(gòu)組織的靜脈輻合帶16引起的

51、。 DVA用血管畸形，動(dòng)靜脈分流，和的動(dòng)脈化的DVA已經(jīng)被描述為早期出現(xiàn)的船只與毛細(xì)管臉紅動(dòng)脈期和早期靜脈充盈血管造影17。這樣DVA變化可以增加的臨床風(fēng)險(xiǎn)這些病變，因此可能需要更頻繁地評(píng)估。在這項(xiàng)研究中，五例的DVA的，以及年齡和sexmatched控制，進(jìn)行回顧上確定整個(gè)腦CT DSA和全腦的CTP如果評(píng)估增加解剖上覆蓋全腦CTP和相對(duì)CTP參數(shù)的收集可以為DVA識(shí)別增量診斷信息和診斷。討論 這項(xiàng)研究表明，CTP可允許與DVA相關(guān)的血流動(dòng)力學(xué)改變的評(píng)估。對(duì)于每個(gè)DVA在這項(xiàng)研究中，絕對(duì)CBV和CBF值顯著在受影響的半球相比未受影響的半球增加。在MR灌注，卡馬喬等人。 12還發(fā)現(xiàn)增加CBF，

52、CBV，MTT法和四個(gè)簡單的DVA案件。作者 得出的結(jié)論是血流動(dòng)力學(xué)的改變并沒有與患者的表現(xiàn)癥狀相關(guān)聯(lián)，而改變并不意味著對(duì)DVA更不祥的未來結(jié)果。本研究的結(jié)果表明， 加強(qiáng)區(qū)域CBV和CBF對(duì)CTP可以指示DVA對(duì)大腦和殼體1帶有可能是受到了DVA的存在面部麻木癥狀的CTP存在下進(jìn)行。以前的研究已經(jīng)確定了近兩個(gè)大DVA氙增強(qiáng)CT21，在一個(gè)病人的腦血流灌注顯像的信，作者是相關(guān)的SPECT異常，DVA位置，腦電圖焦點(diǎn)22薄壁降低CBF值。然而，血管內(nèi)的分化 血流動(dòng)力學(xué)變化，并使用ROI的方法在本研究中周圍腦實(shí)質(zhì)灌注的變化是由于利用DVA和周圍實(shí)質(zhì)的像素由像素的評(píng)價(jià)將ROI內(nèi)的CTP值和未來研究的平

53、均值限定能夠提供一個(gè)答案。雖然MTT法一貫升高，暗示在這個(gè)小組5例延遲或緩流，需要進(jìn)一步研究，以確定如何全腦血流動(dòng)力學(xué)（即，CBV和CBF）和時(shí)間的CTP值（即，MTT，TTP，和延遲）的DVA內(nèi)可用于進(jìn)一步描繪血流動(dòng)力學(xué)參數(shù)的DVA的情況下，較大的集合。因?yàn)镸TT是灌注壓的一個(gè)指標(biāo)，在DVA較高的MTT值表示較低的流量或灌注，并增加MTT值先前已與DVA的相聯(lián) 四名患者的MR灌注12。每宗個(gè)案的影響半球似乎是影響相對(duì)百分比變化MTT值，但因?yàn)槲⒉蛔愕赖腜值和樣本量小，趨勢(shì)MTT值在患者與DVA隨著時(shí)間的評(píng)估，需要進(jìn)一步的研究。 TTP結(jié)果DVA案件必須解釋在每個(gè)患者的情況下。 TTP為并不代

54、表DVA在這項(xiàng)研究中。這可能是由于在寬 范圍DVA類型，既可以增加和減少的時(shí)間，血液得到一個(gè)地區(qū)。 TTP是，可以根據(jù)被錯(cuò)誤地延長的時(shí)間參數(shù) 掃描過程中和通過動(dòng)脈輸入函數(shù)的大小和形狀的技術(shù)因素。例1，圖3和4中受影響的半球（范圍1.99-6.45），其結(jié)果顯示的對(duì)比度，以較慢的到來有較高的相對(duì)的TTP DVA。這可能是在預(yù)期流動(dòng)緩慢靜脈結(jié)構(gòu)與對(duì)TTP的價(jià)值觀動(dòng)脈影響較低的比例。對(duì)于例2和5，快速流動(dòng)和相對(duì)較低的TTP（如遇-4.09，5至-7.43的情況下，2）在受影響的半球可以解釋為從可能的動(dòng)靜脈分流分量的貢獻(xiàn)，但這種無法證實(shí)也沒有動(dòng)脈異常者注意到CT機(jī)DSA的情況下，2和5。進(jìn)一步DVA的

55、個(gè)案分析將需要評(píng)估，如果TTP可作為stratifier的CTP壓力，DVA和可能的CTP參數(shù)可與CBV，CBF結(jié)合，和MTT結(jié)果，有助于描繪未來并發(fā)癥的個(gè)人風(fēng)險(xiǎn)。 DVA的流動(dòng)有關(guān)的并發(fā)癥，可能導(dǎo)致癥狀表現(xiàn)包括因動(dòng)靜脈分流，減少流出，或增加流入 遠(yuǎn)程分流靜脈壓增高10。在我們的研究中，情況1出現(xiàn)的癥狀，可能是繼發(fā)于DVA（圖5）。 Pereira等人。大型和復(fù)雜的DVA與建議靜脈淤血，急性或亞急性缺血性改變，不對(duì)稱的延髓區(qū)的外觀，以及協(xié)會(huì)與動(dòng)靜脈畸形10在MRI上的變化：對(duì)癥DVA呈現(xiàn)的風(fēng)險(xiǎn)增加建議的特點(diǎn)。周圍的DVA顱內(nèi)結(jié)構(gòu)的機(jī)械性壓迫所產(chǎn)生的癥狀在20.3（1469例）。不明原因的癥狀發(fā)

56、生于8.7（截至69例），同時(shí)對(duì)癥DVA其余71（4969例）是由于流相關(guān)的病理機(jī)制（19與流入增加，26與流出減少，以及四個(gè)與分流的 靜脈壓增高）10。本研究的結(jié)果表明，在DVA解剖變異可影響血流動(dòng)力學(xué)流的特征可以評(píng)估通過CTA-V（圖4d）的組合，wholebrain 動(dòng)態(tài)卷的CTP，和4D DSA檢查。正如哈穆德等人審閱。 13，與DVA相關(guān)的非出血性腦缺血是罕見的，很少有文獻(xiàn)報(bào)道。審查將由等。 23第15研究包括714例DVA發(fā)現(xiàn)少于1是與梗死相關(guān)的初始 演示文稿。與DVA相關(guān)的非出血性梗死的病因已被提議作為收集的血栓形成或引流靜脈13，并已確定在血管造影24。狹窄的DVA的硬腦膜開口也經(jīng)常提到，這已被提議作為一種