MR imaging of portal venous thrombosis: correlation with CT and sonography

Fourteen patients with portal venous thrombosis (PVT) diagnosed by CT and/or sonography were studied with MR. Three of the 14 had portal hypertension. The MR findings were compared with those of eight patients with portal hypertension, but without CT or sonographic evidence of PVT. MR imaging showed portal venous thrombosis in all 14 PVT cases. Intraluminal thrombi of less than 5 weeks duration appeared markedly hyperintense relative to liver and muscle on both T1- and T2-weighted images. Older thrombi appeared hyperintense relative to liver and muscle in eight of 11 cases, but only on T2-weighted images. MR showed thrombi in 11% more portal vessels than did CT (MR = 30, CT = 27) and in 28% more vessels than did sonography (MR = 32, sonography = 25). MR also showed 24% more collateral vessels than did CT (MR = 31, CT = 25) and 50% more vessels than did sonography (MR = 33, sonography = 22). Third-echo images (echo time = 96 msec, repetition time = 1500-2150 msec) verified the presence of venous thrombi in 28 (93%) of 30 PVT vessels, and they differentiated flow-related intravascular signal from true thrombi in six (17%) of 36 portal hypertension vessels. We conclude that MR is a valuable tool for imaging portal vein thrombosis. MR is a good substitute for CT and can be more informative than sonography.     

Tributary venosinus occlusion and septic cavernous sinus thrombosis: CT and MR findings.

PURPOSEIn autopsy reports of patients who died of septic cavernous sinus thrombosis, tributary venosinus occlusion has been a common finding related to intracranial inflammatory complications. The purpose of this article is to illustrate the MR and CT appearance of septic cavernous sinus thrombosis and tributary venous occlusion.METHODSOver a period of 7 years, eight patients with septic cavernous sinus thrombosis were examined by contrast-enhanced thin-section CT. The CT scans of these eight patients and those of 30 healthy control subjects were assessed independently and subjectively by two blinded readers to ascertain the presence, size, and density of areas of nonopacification within the cavernous sinus and the presence of filling defects and dilation of tributary veins and venous sinuses. In six subjects, MR images supplemented by a contrast-enhanced spoiled gradient-recalled acquisition in the steady state (SPGR) sequence were assessed with respect to the presence of filling defects, expansion, and signal abnormalities within the cavernous sinus and tributary veins and sinuses. The MR and CT findings were compared.RESULTSThe CT studies of the eight patients were consistently differentiated from those of the control subjects by the two readers. Contrast-enhanced CT findings in patients included areas of nonopacification that were present within the cavernous sinus bilaterally in six cases and unilaterally in two. The size of the filling defects exceeded 7 mm in 76% of thrombosed cavernous sinuses compared with 9% of control subjects. The mean density of filling defects in patients differed significantly from those in control subjects. Comparison of the MR and CT findings in six cases showed the contrast-enhanced SPGR sequence to be equivalent to CT with respect to delineation of filling defects.CONCLUSIONContrast-enhanced high-resolution CT findings indicate that venosinus thrombosis associated with septic cavernous sinus thrombosis is not restricted to the superior ophthalmic vein and is more common than previously assumed. A contrast-enhanced SPGR MR sequence may be used as a reliable alternative to establish the diagnosis of cavernous sinus and tributary venosinus thrombosis.     

静脉窦血栓形成的CT和MR影像特点

目的：研究静脉窦血栓形成（ＶＳＴ）的ＣＴ和ＭＲ特点。方法：对１７例ＶＳＴ的ＣＴ和ＭＲ特点进行回顾性影像分析，重点研究ＶＳＴ与皮层下多发性脑内血肿（ＳＣＭＨ）的联系，诊断与鉴别诊断。结果：ＳＣＭＨ在ＶＳＴ中出现率为１００％（１７／１７）。９例ＶＳＴ病例ＭＲ随访显示血肿、水肿和静脉窦内血栓进行性吸收，血肿周围可见规则完整的含铁血黄素沉积圈。结论：ＣＴ上急性ＳＣＭＨ是ＶＳＴ很强的一个诊断指征。ＭＲ可以进一步除外瘤卒中，发现静脉窦内血栓，以明确ＶＳＴ的诊断     

脑静脉及静脉窦血栓21例CT磁共振表现及漏误诊分析

目的总结颅内静脉与静脉窦血栓形成(CVST)的CT及磁共振(MR)表现,分析漏误诊的原因。方法回顾性分析21例CVST病例的CT和MR影像,全部病例均有MR资料,12例有低场强磁共振脑静脉窦血管成像(MRV)资料,15例有CT资料。结果 CVST的CT表现为病变静脉窦的高密度影、束带征及Delta征;MR主要表现为病变静脉窦内短T1长T2信号;MRV表现为血栓形成静脉窦的闭塞;本组21例CVST,影像科初诊漏诊2例,误诊5例。结论正确认识CVST的束带征、急性早期征象及静脉性脑梗死的改变,能减少漏误诊的发生。     

Intravascular hematocrit effect in cross-sectional CT imaging

Venous fluid-fluid levels were seen on CT or MR of three patients being evaluated for possible thrombosis. In all three cases, further investigation (by ultrasonography, venography, or surgery) revealed the cause of the fluid-fluid level to be slowly flowing blood without thrombosis. On CT done after intravenous contrast medium administration, the nondependent half of the vessel was denser than the dependent half. In an attempt to confirm this MR and CT picture and, particularly, to explain the dense upper half on CT, we conducted an in vitro study. Our study confirmed that when blood with diatrizoate sodium is not clotted and allowed to settle, a similar fluid-fluid level is observed by CT imaging. Our results indicate that an intravascular fluid-fluid level seen on cross-sectional images represents slowly flowing blood, not thrombosis.     

Imaging in acute basilar artery thrombosis

The aim of this study was to review the imaging features in acute (<24 h) basilar artery thrombosis. CT and MR studies in 11 patients with clinical diagnosis of acute basilar artery thrombosis were retrospectively reviewed. MR angiography was obtained in 4 patients. Correlation with clinical symptoms was performed. Multiple cranial nerve palsies and hemiparesis were the most common clincal symptoms at presentation. CT revealed hyperdense basilar arteries (n=7) and hypodensities in the posterior circulation territory (n=8). In one instance, the infarction was hemorrhagic. MR imaging showed absence of flow void within the basilar in 6 patients and MRA (using both PC and TOF techniques) confirmed absence of blood flow in 4 basilar arteries. One week after presentation, 5 patients died. Autopsy was obtained in 1 case and confirmed the diagnosis of basilar artery thrombosis. Basilar artery thrombosis has fairly typical imaging features by both CT and MR. MRA may be used to confirm the diagnosis. Prompt recognition may lead to early thrombolytic treatment and may improve survival.     

Intracranial aneurysms: MR imaging

Summary MR studies of 17 patients with 19 intracranial aneurysms are reviewed. All patients also underwent CT and angiography. MR has been able to visualize the aneurysms in all cases. Aneurysms present various MR appearances because of flow characteristics, thrombosis in different stages of organization, calcific and ferric deposits. Based on MR signal changes it is possible to distinguish between flow effects and histopathological components such as thrombosis. Flow patterns are complex and sometimes it is difficult to define the cause responsible for intraluminal signal. MR allows a precise definition of perilesional brain tissue and demonstrates associated lesions. Angiography remains the definitive procedure in the diagnosis of small aneurysms, but shows only that part of the lesion in continuity with the circulation. MR clearly delineates the size, the residual lumen and the extraaxial location of giant aneurysms. In completely thrombosed aneurysms, when CT suggest a tumor, MR is able to demonstrate the vascular nature of the lesion.     

Imaging of vascular complications after hepatic transplantation

Vascular complications after hepatic transplantation can compromise graft and patient survival. Angiography defines the need for revascularization or retransplantation, but the value of noninvasive imaging in this setting is not clear. To assess the relative merit of noninvasive imaging techniques (sonography, scintigraphy, CT, and MR), we retrospectively reviewed 19 major vascular complications that occurred in 15 of 98 hepatic recipients over a 3 1/2-year period. Portal venous thrombosis was seen in seven patients, donor aortic or hepatic arterial thrombosis in seven, and inferior vena caval thrombosis in five. Sonography provided the initial diagnosis of portal venous thrombosis in three, arterial compromise in five, and caval obstruction in four. CT was the first diagnostic examination to identify portal occlusion in two, donor aortic thrombosis in one, and inferior vena caval thrombosis in one. Scintigraphy and MR imaging provided complementary data. Both sonography and CT are useful in the evaluation of vascular complications that occur after hepatic transplantation; however, neither is sufficiently sensitive to obviate angiographic assessment.     

Acute thrombosis of the intracranial dural sinus: direct thrombolytic treatment.

Acute intracranial dural sinus thrombosis may have severe morbidity or fatal complications without appropriate treatment. Direct dural sinus venography can be performed safely with a soft Tracker catheter to document the fresh thrombus as an adjunct to CT or MR. We are reporting our experience with successful direct urokinase thrombolytic therapy in three cases of superior sagittal sinus and two cases of transverse and sigmoid sinus thrombosis. All five patients have recovered completely without any residual clinical deficit.     

Mesenteric venous thrombosis: diagnosis and noninvasive imaging.

Mesenteric venous thrombosis is an uncommon but potentially lethal cause of bowel ischemia. Several imaging methods are available for diagnosis, each of which has advantages and disadvantages. Doppler ultrasonography allows direct evaluation of the mesenteric and portal veins, provides semiquantitative flow information, and allows Doppler waveform analysis of the visceral vessels; however, it is operator dependent and is often limited by overlying bowel gas. Conventional contrast material-enhanced computed tomography (CT) allows sensitive detection of venous thrombosis within the central large vessels of the portomesenteric circulation and any associated secondary findings; however, it is limited by respiratory misregistration, motion artifact, and substantially decreased longitudinal spatial resolution. Helical CT and CT angiography, especially when performed with multi-detector row scanners, and magnetic resonance (MR) imaging, particularly gadolinium-enhanced MR angiography, enable volumetric acquisitions in a single breath hold, eliminating motion artifact and suppressing respiratory misregistration. Helical CT angiography and three-dimensional gadolinium-enhanced MR angiography should be considered the primary diagnostic modalities for patients with a high clinical suspicion of mesenteric ischemia. Conventional angiography is reserved for equivocal cases at noninvasive imaging and is also used in conjunction with transcatheter therapeutic techniques in management of symptomatic portal and mesenteric venous thrombosis.     

Cerebellar infarct caused by spontaneous thrombosis of a developmental venous anomaly of the posterior fossa

Spontaneous thrombosis of a posterior fossa developmental venous anomaly (DVA) caused a nonhemorrhagic cerebellar infarct in a 31-year-old man who also harbored a midbrain cavernous angioma. DVA thrombosis was well depicted on CT and MR studies and was proved at angiography by the demonstration of an endoluminal clot.     

Spontaneous thrombosis of developmental venous anomaly (DVA) with venous infarct and acute cerebellar ataxia

Developmental venous anomaly (DVA), formally known as venous angioma, is a congenital anatomic variant of the venous drainage of the brain. Although they typically have a benign clinical course and a low symptomatic rate, thrombosis of a drainage vein may occur, leading to potentially debilitating complications. We report a unique case of spontaneous thrombosis of a posterior fossa developmental venous anomaly with cerebellar infarct in a 61-year-old man who presented with acute onset cerebellar ataxia. DVA thrombosis was well-depicted on CT and MR studies. Patient was put on anticoagulant therapy and complete recanalization was seen on follow-up imaging.     

颅内静脉血栓形成的磁共振诊断

目的:探讨磁共振成像(MRI)及磁共振静脉成像(MRV)对颅内静脉窦血栓形成(CVST)的诊断价值。方法:回顾性分析经临床和影像学方法确诊的14例CVST患者。MR检查技术包括平扫,增强扫描及MRV,14例均行CT平扫,其中1例行DSA检查。结果:14例CVST累及上矢状窦血栓形成4例,横窦血栓形成6例、乙状窦5例,MRI可清晰显示颅内静脉窦血栓形成的直接征象和间接征象,MRV可显示受累静脉窦不显影或者充盈缺损形成。结论:常规MRI结合MRV对颅内静脉窦血栓形成的早期诊断具有重要价值。     

Pure motor hemiparesis in a case of vertebrobasilar arterial ectasia

Summary A case of pure motor hemiparesis due to a pontine lacunar infarct is reported. Infarction was related to vertebrobasilar ectasia identified on CT, MRI and MR angiography. MR studies provide accurate information on anatomical location, residual lumen, partial thrombosis, mass effect on brain stem and CSF pathways and vascular complications.     

Is true FISP imaging reliable in the evaluation of venous thrombosis?

OBJECTIVE: The objective of our study was to evaluate the accuracy of true fast imaging with steady-state precession (FISP) in the diagnosis of venous thrombosis using gadolinium-enhanced 3D T1-weighted gradient-echo images and correlative imaging as the gold standard. MATERIALS AND METHODS: Twenty-five MR examinations were retrospectively reviewed independently by two radiologists to rule out thrombosis in the central veins of the body. The presence of venous thrombus was assessed separately in 80 veins using true FISP and gadolinium-enhanced T1-weighted images. Diagnosis was confirmed by another imaging technique (sonography, CT, and/or conventional venography) in all positive cases. Negative examinations were confirmed using imaging, clinical follow-up, or both. RESULTS: Venous thrombosis was present in 25 veins in 18 patients. True FISP images had a lower sensitivity (66%) and specificity (70.9%) for the diagnosis of venous thrombosis than gadolinium-enhanced MR images (p < 0.01). CONCLUSION: True FISP images have lower sensitivity and specificity in the diagnosis of venous thrombosis than gadolinium-enhanced T1-weighted gradient-echo images. True FISP images should not be used exclusively for the diagnosis of venous thrombosis.     

Cerebral venous thrombosis as a rare cause of subarachnoid hemorrhage: case report and literature review

We report a 48-year-old woman presenting with subarachnoid hemorrhage (SAH) as the first manifestation of superior sagittal sinus thrombosis. In a literature review of 73 cases, SAH associated with cerebral venous thrombosis (CVT) was usually seen at the cerebral convexities. SAH was adjacent to thrombosed venous structures; therefore, the most possible explanation seems to be the rupture of cortical veins due to extension of thrombosis. Computed tomography (CT) was effective for diagnosis of CVT in only 32% of the cases. CVT should be considered when SAH is limited to cerebral convexities and magnetic resonance (MR) imaging with MR venography should be performed.     

MRI assessment of unsuspected dural sinus thrombosis

Summary In three patients with clinically unsuspected diagnosis, MRI has afforded a positive and conspicuous demonstration of dural sinus thrombosis, allowing specific treatment and followed by improvement in the patients' condition. Even in retrospect, CT examinations were nondiagnostic. Presenting symptoms were usual and nonspecific. CT and radionuclide scanning have proved valuable when performed on a clinically oriented basis. Angiography cannot be carried out without clear indications. MRI offers advantages in being a non-invasive technique without ionising radiation, allowing direct visualization and accurate delineation of the thrombus. MRI is definitely the method of choice to assess clinically suspected cerebral venous occlusion. As MR diagnosis relies on a routine examination protocol, we believe that it will detect other unsuspected cases of dural sinus thrombosis.     

Magnetic resonance portal venography: use of fast-acquisition true FISP imaging in the detection of portal vein thrombosis

AIM: To determine the accuracy of true fast imaging with steady-state precession (true FISP) in the diagnosis of portal vein thrombosis in patients with cirrhosis and compare it to contrast-enhanced three-dimensional (3D) magnetic resonance (MR) angiography, the reference standard. MATERIALS AND METHODS: Twenty-four consecutive patients with suspected portal venous thrombosis underwent contrast-enhanced 3D MR angiography and true FISP imaging of the portal vein. All patients had undergone at least one other imaging study, either computed tomography, (CT) or ultrasound. Both sets of MR images were evaluated for patency of the portal venous system and for image quality. RESULTS: Portal vein thrombosis was diagnosed in six of the 24 patients. Four patients with portal vein thrombosis were accurately diagnosed on the true FISP sequence. This sequence also accurately diagnosed the patency of the portal vein in 17 patients. However, the results were inconclusive in three patients. The image quality of the true FISP sequence of the three inconclusive patients was graded as either poor or fair. Of these three patients, contrast-enhanced 3D MR angiography confirmed portal vein thrombosis in two patients and portal vein stenosis in one patient. True FISP imaging had a sensitivity of 67% and a specificity of 100% for the diagnosis of portal vein thrombosis. CONCLUSION: The results of the present study show that the true FISP sequence is useful in diagnosing portal vein thrombosis. It could be employed as an adjunct to contrast-enhanced MR angiography in the severely debilitated patient where respiratory motion may degrade the images or in patients where the use of intravenous contrast medium is not possible due to poor venous access.     

Spontaneous hemorrhage from a cerebral venous malformation related to thrombosis of the central draining vein: demonstration with angiography and serial MR.

A cerebral venous malformation ruptured after acute thrombosis of its central draining venous channel, leading to intracerebral hemorrhage. The CT, MR, and angiographic studies unequivocally demonstrated subsequent progressive recanalization of the malformation, providing proof that venous malformations can spontaneously bleed and that venous thrombosis may be associated with, and perhaps produce, the hemorrhage.     

Giant intracranial aneurysms: MR imaging

Fifteen patients with giant intracranial aneurysms were examined with magnetic resonance (MR) imaging, computed tomography (CT), and angiography. MR imaging revealed a rounded extraaxial mass with evidence of intraluminal blood flow in 12 of the 15 cases. Signal void within the lumen was seen in all 12 of these cases. Other flow effects, such as even-echo rephasing, were seen in some cases. Complete thrombosis was seen in three giant aneurysms in which high signal intensity on T1- and T2-weighted images filled the lumen, and no flow effects were seen. Partial thrombosis was detected in four aneurysms as persistent areas of medium to high signal intensity within the lumen on T1- and T2-weighted images. In five cases, the cause of the intraluminal signal that was present was difficult to determine. The ability of MR to indicate flow within the lumen in 12 of 15 cases provided for greater diagnostic confidence than with CT, which was strongly suggestive of an extraaxial tumor in nine patients. Calcification of the wall of the aneurysm was better detected with CT.