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. 靜脈發育異常：全腦CT數字減影血管造影和CT灌注的表現簡介靜脈發育異常(DVA)由擴張的髓內靜脈組成，匯合成一個大收集靜脈。全腦計算機斷層掃描（CT）數字減影血管造影（DSA）和CT灌注（CTP）的研究對這些異常表現進行了評估。方法對10例匿名患者的CT數據資料進行回顧性分析。5例患者具有DVA的證據，而五例年齡和性別匹配的對照病例并沒有已知的血管神經異常。通過一個動態容積成像協議，在320排CT探測器掃描儀上獲取CT血管造影，CT動脈靜脈圖像，4-D CT數字血管造影和CT灌注圖像。 腦血流量（CBF），腦血容量（CB

47、V）， 達峰時間（TTP），平均通過時間（MTT）和延遲對全腦CT灌注參數進行評價。利用DSA對DVA解剖可視化。掃描儀控制臺記錄輻射劑量。結果CTP值增加出現在DVA的患者中，相對于未受影響的對側半球，CBF，CBV，MTT分別增加48，32，和26; 而對照組為2，-10和9。平均有效輻射劑量為4.4毫西弗。結論全腦CTA和CTP成像能顯示的DVA血流動力學參數變化的特征表現和捕捉大腦和小腦皮質的異常。未來的研究可以識別繼發于血流動力學改變的不良后果而導致風險增加的患者，以促進針對性成像顯示和適當的預防治療措施的應用。關鍵詞計算機斷層掃描 CT血管造影 CT灌注 靜脈發育異常 全腦CT灌注

48、 發育靜脈異常（DVA）表示可與其他腦血管畸形相關聯的正常變異。DVA先前已被稱為靜脈血管瘤，靜脈畸形，和髓靜脈畸形1。DVA可位于整個大腦，并已被描述為近皮層，皮質下，或深。深的DVA是通過幕上和幕下位置進一步細分2。宏觀上，DVA已經被描述為是漏白且徑向和心地灰質成一個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張薄壁髓質血管引流靜脈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。在一個顱磁共振成像（MRI）的8200例患者的調查，DVA存在于50，提示0.6的時點患病率6。拋尸的4069箱子研究報告說，DVA存在于2.57。 DVA是已知與血管有關的畸形，包括動靜

49、脈畸形AVM），海綿狀血管瘤（CM），和毛細管毛細血管擴張8,9。達的患者DVA的第三可以具有第二腦血管異常，如CM9。孤立DVA被認為是先天的性質和一般遵循良性的自然史。然而，對癥DVA已經越來越臨床確定10和神經癥狀，如頭痛，抽搐，感覺異常，運動障礙，三叉神經痛，和錐體外系障礙已經報道11。DVA已經確定在計算機斷層掃描（CT），磁共振成像（MRI），單光子發射計算機斷層顯像（SPECT），常規 血管造影和數字減影血管造影（DSA），并可能會顯示在每個這些方式的幾個特征影像學特征。關于增強CT，靜脈收集系統的線性或曲線特征是經常存在的。在noncontrast MR，DVA可以出現在T1-

50、管狀信號空隙和T2加權序列8和可變程度的T1和T2延長可以看出在相鄰的實質12。對比增強MRI，引流靜脈增強 提供DVA結構的改進的可視化。彌散加權成像，DVA被血栓或梗塞可能顯示為限制擴散與區域 明亮的信號強度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）參數只被最近描述15。這可能是繼發于全腦覆蓋在先前技術的限制未允許完全可視化在外圍或優于大腦皮層在DVA的流動相關的病理機制的理解的最新進展，包括癥狀繼發于他們的輸入和流出的血流動力學10的風險增加。可以通過成像檢測血流動力學的變化，可以通過采集靜脈流出道梗阻，靜脈壁增厚進取和結構組織的靜脈輻合帶16引起的

51、。 DVA用血管畸形，動靜脈分流，和的動脈化的DVA已經被描述為早期出現的船只與毛細管臉紅動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險這些病變，因此可能需要更頻繁地評估。在這項研究中，五例的DVA的，以及年齡和sexmatched控制，進行回顧上確定整個腦CT DSA和全腦的CTP如果評估增加解剖上覆蓋全腦CTP和相對CTP參數的收集可以為DVA識別增量診斷信息和診斷。討論 這項研究表明，CTP可允許與DVA相關的血流動力學改變的評估。對于每個DVA在這項研究中，絕對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還發現增加CBF，

52、CBV，MTT法和四個簡單的DVA案件。作者 得出的結論是血流動力學的改變并沒有與患者的表現癥狀相關聯，而改變并不意味著對DVA更不祥的未來結果。本研究的結果表明， 加強區域CBV和CBF對CTP可以指示DVA對大腦和殼體1帶有可能是受到了DVA的存在面部麻木癥狀的CTP存在下進行。以前的研究已經確定了近兩個大DVA氙增強CT21，在一個病人的腦血流灌注顯像的信，作者是相關的SPECT異常，DVA位置，腦電圖焦點22薄壁降低CBF值。然而，血管內的分化 血流動力學變化，并使用ROI的方法在本研究中周圍腦實質灌注的變化是由于利用DVA和周圍實質的像素由像素的評價將ROI內的CTP值和未來研究的平

53、均值限定能夠提供一個答案。雖然MTT法一貫升高，暗示在這個小組5例延遲或緩流，需要進一步研究，以確定如何全腦血流動力學（即，CBV和CBF）和時間的CTP值（即，MTT，TTP，和延遲）的DVA內可用于進一步描繪血流動力學參數的DVA的情況下，較大的集合。因為MTT是灌注壓的一個指標，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 四名患者的MR灌注12。每宗個案的影響半球似乎是影響相對百分比變化MTT值，但因為微不足道的P值和樣本量小，趨勢MTT值在患者與DVA隨著時間的評估，需要進一步的研究。 TTP結果DVA案件必須解釋在每個患者的情況下。 TTP為并不代

54、表DVA在這項研究中。這可能是由于在寬 范圍DVA類型，既可以增加和減少的時間，血液得到一個地區。 TTP是，可以根據被錯誤地延長的時間參數 掃描過程中和通過動脈輸入函數的大小和形狀的技術因素。例1，圖3和4中受影響的半球（范圍1.99-6.45），其結果顯示的對比度，以較慢的到來有較高的相對的TTP DVA。這可能是在預期流動緩慢靜脈結構與對TTP的價值觀動脈影響較低的比例。對于例2和5，快速流動和相對較低的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靜脈分流分量的貢獻，但這種無法證實也沒有動脈異常者注意到CT機DSA的情況下，2和5。進一步DVA的

55、個案分析將需要評估，如果TTP可作為stratifier的CTP壓力，DVA和可能的CTP參數可與CBV，CBF結合，和MTT結果，有助于描繪未來并發癥的個人風險。 DVA的流動有關的并發癥，可能導致癥狀表現包括因動靜脈分流，減少流出，或增加流入 遠程分流靜脈壓增高10。在我們的研究中，情況1出現的癥狀，可能是繼發于DVA（圖5）。 Pereira等人。大型和復雜的DVA與建議靜脈淤血，急性或亞急性缺血性改變，不對稱的延髓區的外觀，以及協會與動靜脈畸形10在MRI上的變化：對癥DVA呈現的風險增加建議的特點。周圍的DVA顱內結構的機械性壓迫所產生的癥狀在20.3（1469例）。不明原因的癥狀發

56、生于8.7（截至69例），同時對癥DVA其余71（4969例）是由于流相關的病理機制（19與流入增加，26與流出減少，以及四個與分流的 靜脈壓增高）10。本研究的結果表明，在DVA解剖變異可影響血流動力學流的特征可以評估通過CTA-V（圖4d）的組合，wholebrain 動態卷的CTP，和4D DSA檢查。正如哈穆德等人審閱。 13，與DVA相關的非出血性腦缺血是罕見的，很少有文獻報道。審查將由等。 23第15研究包括714例DVA發現少于1是與梗死相關的初始 演示文稿。與DVA相關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的硬腦膜開口也經常提到，這已被提議作為一種