The relationship between cerebral infarction and angiographic characteristics in childhood moyamoya disease

BACKGROUND AND PURPOSE: In childhood-onset moyamoya disease, the angiographic disease process of stenoocclusive lesions is progressive, and cerebral infarctions often develop as a result of ischemia. Our purpose was to determine how the severity of stenoocclusive lesions in the anterior and posterior circulations affects the distribution of cerebral infarction in patients with childhood-onset moyamoya disease. METHODS: In 69 patients with childhood-onset moyamoya disease, angiograms were reviewed for stenoocclusive lesions, and CT scans, MR images, or both were reviewed for the sites and extent of cerebral infarction. The relationship between the angiographic and CT/MR findings was examined. RESULTS: The prevalence and degree of stenoocclusive lesions of the posterior cerebral artery (PCA) significantly correlated with the extent of lesions around the terminal portion of the internal carotid artery (ICA). The prevalence of infarction significantly correlated with the degree of stenoocclusive changes of both the ICA and PCA. Infarctions tended to be distributed in the anterior borderzone in less-advanced cases, while in more advanced cases lesions were additionally found posteriorly in the territory of the middle cerebral artery, the posterior borderzone, and the PCA territory. CONCLUSION: Our results indicate that progressive changes of the anterior and posterior circulations are associated with the distribution of cerebral infarction, culminating in a patchily disseminated or honeycomb pattern of infarction on CT and MR studies in late stages of the disease.     

Zonal frequency analysis of the gyral and sulcal extent of cerebral infarcts. Part III: Middle cerebral artery and watershed infarcts

We tested the hypothesis that frequency analysis of the anatomic zones affected by single anterior (A), posterior (P), and middle (M) cerebral artery (CA), multivessel, and watershed infarcts will disclose specific sites (peak zones) most frequently involved by each type, sites most frequently injured by multiple different types (vulnerable zones), and overlapping sites of equal relative frequency for two or more different types of infarct (equal frequency zones). We adopted precise definitions of each vascular territory. CT and MRI studies of 50 MCA, 20 ACA-MCA, three PCA-MCA, and 30 parasagittal watershed infarcts were mapped onto a standard template. Relative infarct frequencies in each zone were analyzed within and across infarct types to identify the centers and peripheries of each, vulnerable zones, and equal frequency zones. These data were then correlated with the prior analysis of 47 ACA, PCA, dual ACA-PCA, and ACA-PCA-MCA infarcts. Zonal frequency data for MCA and watershed infarcts, the sites of peak infarct frequency, the sites of vulnerability to diverse infarcts, and the overlapping sites of equal infarct frequency are tabulated and displayed in standardized format for direct comparison of different infarcts. This method successfully displays the nature, sites, and extent of individual infarct types, illustrates the shifts in zonal frequency and lesion center that attend dual and triple infarcts, and clarifies the relationships among the diverse types of infarct.     

Differentiation of recent and old cerebral infarcts by diffusion-weighted MRI

We performed MRI, including diffusion-weighted imaging, in 15 patients with recurrent strokes with acute ischaemia and at least one old lesion according to the clinical history and/or CT. Routine MRI showed similar signal intensity changes in both situations. Diffusion-weighted images, however, were positive in all acute or subacute infarcts. The high signal of acutely disturbed diffusion due to intracellular oedema could also be identified in small brain stem lesions. Spatial resolution was increased by applying separate gradients in each axis instead of creating anisotropy-independent trace images. Received: 17 September 1997 Accepted: 6 April 1998     

The vascular territories in the cerebellum and brainstem: CT and MR study

More than 100 CT and 15 MR studies of infarcts in the cerebellum and brainstem were reviewed to define the most typical distribution of infarcts in the different vascular territories. Posterior inferior cerebellar artery and anterior inferior cerebellar artery territories are variable in size and are in a sort of equilibrium with each other. The posterior inferior cerebellar artery territory in transverse sections reveals a characteristic posterior crescent caused by its cranial posterior extension. The anterior inferior cerebellar artery territory may be limited to the lateral inferior pontine and floccular regions but usually extends over the whole petrosal surface of the cerebellum up to the lateral angle. Superior cerebellar artery territory is the most extensive territory and includes the largest part of the deep white matter. Infarcts in a single-branch distribution, vermian or hemispheric, have a characteristic sagittal or oblique orientation. Watershed cerebellar infarcts can also be recognized. In the brainstem, paramedian, lateral, and dorsal penetrating arteries have characteristic distributions at the medullary, pontine, and mesencephalic levels. With MR, lateral medullary infarcts can be demonstrated. Paramedian penetrating arteries are paired, and symmetric and small infarcts at medullary and pontine levels are sharply delimited on the midline. At the mesencephalic level, infarcts in this distribution usually involve all the arteries originating from the tip of the basilar artery and from the precommunicating segment of the posterior cerebral arteries, resulting in a central mesencephalic infarct with bilateral upward extension in the thalami. The different vascular territories in the cerebellum and in the brainstem are illustrated in schematic drawings in transverse, coronal, and sagittal planes. Knowledge of the vascular territories gained by the multiplanar capabilities of MR, and knowledge of the CT patterns of enhancement and evolution, will improve recognition and definition of infarcts.     

MRI in occipital lobe infarcts: classification by involvement of the striate cortex

We reviewed the MRI studies of 25 patients with occipital lobe infarcts to clarify the distribution of infarcts in the posterior cerebral arterial territory, focussing on their relationship to the striate cortex. Visual field defects and MRI findings were also correlated in 16 patients. On coronal and/or sagittal images, the distribution of the infarct and its relationship to the striate cortex were classified. Involvement of the cortex of both upper and lower lips of the calcarine fissure was observed in 10 patients, and involvement of the lower lip alone in 15. The upper cortical lesions were always accompanied by lower cortical lesions. The visual field defects were complete hemianopia in nine patients, superior quadrantanopia in six and hemianopia with a preserved temporal crescent in one. All patients with superior quadrantanopia had involvement of the lower cortex alone; there were no cases of inferior quadrantanopia. The characteristic vascular anatomy, and poor development of the collateral circulation in the lower cortical area, may explain the vulnerability of this area to infarcts. Received: 12 January 1998 Accepted: 13 March 1998     

Focal peliosis hepatis as a mimicker of hepatic tumors: radiological-pathological correlation

OBJECTIVE: To retrospectively evaluate the radiological findings in patients with focal peliosis hepatis and to correlate them with pathological findings. METHODS: Eight patients with pathologically proven peliosis hepatis underwent ultrasonography (n = 6), computed tomography (CT; n =8), and/or magnetic resonance imaging (MRI; n = 3). Two radiologists analyzed the images for the size, margin, echogenicity, presence of posterior acoustic enhancement, and enhancement pattern of the lesion. The enhancement patterns on CT or MRI were correlated with the pathological findings. RESULTS: The average lesion size was 1.9 cm. On ultrasonography, 4 lesions were ill defined and low echoic compared with the hepatic parenchyma. Two lesions showed posterior acoustic enhancement. In 4 lesions, centripetal enhancement was observed on dynamic CT images. Two lesions showed homogeneously high and 2 showed persistently low enhancement patterns. On dynamic MR phases, 2 lesions showed strong and persistent enhancement. In 1 lesion, MR showed slow centripetal enhancement. In the 3 patients who showed a homogeneously high enhancement pattern on dynamic CT or MRI, microscopic examination demonstrated that the dilated sinusoids were filled with fresh blood cells. On the contrary, in 5 patients who showed a centripetal or persistently low enhancement pattern, their dilated sinusoids were filled with old stagnated blood. CONCLUSIONS: Focal peliosis hepatis showed various enhancement patterns on contrast-enhanced CT and MRI, depending on the histopathologic findings.     

Ultra high field MRI at 8 Tesla of subacute hemorrhagic stroke

PURPOSE: Optimal treatment strategies and neurologic outcome after stroke depend on an accurate characterization of the lesion. There is a need for high resolution noninvasive imaging for assessment of the infarct size, perfusion, and vascular territory. MRI at the ultra high field (UHF) of 8 T offers unprecedented resolution, but its utility for stroke evaluation has not been determined yet. METHOD: A 55-year-old man with hypertension experienced sudden onset of speech arrest and right-sided hemiparesis that resolved in < 24 h with minimal neurologic deficit. MRI at 1.5 T showed initially a left posterior frontal lesion with subacute infarct (hyperintense on T2-weighted spin echo images) and right-sided frontal and periventricular lesions consistent with chronic infarct. There were many smaller white matter lesions. Delayed studies showed high signal changes involving the gray matter only on T1-weighted images. RESULTS: Gradient echo and rapid acquisition with relaxation enhancement (RARE) multislice images revealed a serpentine area of low signal in the left posterior frontal lobe gray matter suggestive of a hemorrhagic infarct, right-sided frontal lesion also showing iron deposits, multiple periventricular and cortical areas with abnormal high signal regions that were consistent with old infarcts, and numerous small vessels readily visible, more prominent on the right. CONCLUSION: MRI at 8 T displays lesions with a high resolution and striking anatomic details. Susceptibility to iron and sensitivity to detect blood products are increased at 8 T. The imaging characteristics at high field are different from those at low field, but both represent findings of iron products.     

Improved CT diagnosis of acute middle cerebral artery territory infarcts with density-difference analysis

A new postprocessing method is described for CT detection of acute middle cerebral artery (MCA) territory infarcts by histograph analysis of density values. The density values in each CT slice were histographically recorded for each hemisphere. A density-difference diagram was calculated by digital subtraction of the histogram of the left hemisphere from that of the right. Pixels within the highest density-difference ranges were highlighted. To investigate the value of this method CT studies of 30 patients with acute MCA territory infarcts and of 15 normal CT studies were analysed by two radiologists and neurosurgeons. CT images with and without postprocessing were assessed for the presence, site and size of infarcts. Follow-up CT was used as control. With density-difference analysis (DDA) the detection rate for infarcts increased significantly (96 % compared to 61 %). In no case was a correct diagnosis made on the unpostprocessed images falsely revised with DDA. All normal CT studies were detected correctly using DDA. Received: 16 October 1995 Accepted: 20 March 1996     

老年人皮质下动脉硬化性脑病的病理学基础和CT,MRI对照研究

本文就２６例皮质下动脉硬化性脑病患者的ＣＴ、ＭＲＩ检查结合病理学基础进行了分析。ＭＲＩ检查，当ＴＲ＝２０００ｍｓｅｅ，ＴＥ＝３０、６０ｍｓｅｃ时，皮质动脉硬化性脑病损害均为明显的高信号，Ｔ１加权像为低信号。ＣＴ像为低密度改变。Ｔ２加权像上半卵圆中心的白质表现为不均匀弥漫的高信号区，可累及基底节、丘脑、脑干及小脑的白质，并有不同程度的侧脑室扩大、脑室边缘呈斑片状改变可有脑萎缩。病理学特征是弥漫不完全     

Hemodynamically caused cerebral infarctions. Clinical importance of infarct pattern and angiomorphology

Summary Classification of brain infarcts based on the location, size and shape of parenchymal damage alone can be difficult and misleading. This is particularly true in subcortical infarctions and infarcts in so-called watershed areas between neighboring territories of the main hemispheric arteries. Pathogenetic mechanisms, signs and symptoms, lesion patterns in CT and MRI are discussed as well as angiomorphological conditions. Hemodynamically induced low-flow infarcts are rare and show typical, but not pathognomic lesion patterns on CT and MRI. Characteristic subcortical chainlike and confluent lesions are located in the supra- and paraventricular white matter, representing the core of a hemodynamically induced infarction. Definite diagnosis of low-flow infarcts requires information on the underlying complex vascular compromise of the extra- and intracranial arterial circulation. A noncompetent circle of Willis is the main predisposing condition in hemispheric low-flow infarcts even in severe occlusive disease of the internal carotid arteries.      

Moyamoya disease: diagnostic accuracy of MRI

Our purpose was to evaluate the diagnostic accuracy of MRI in moyamoya disease. We studied 30 patients with this disease, comparing MRI and angiographic findings. The diagnostic value of MRI was evaluated for occlusive lesions, collateral vessels, and parenchymal lesions. In all patients bilateral occlusion or stenosis of the supraclinoid internal carotid artery and proximal anterior and middle cerebral arteries was clearly shown by MRI, and staging of the extent of occlusion agreed with angiographic staging in 44 (73%) of 60 arteries. MRI, particularly coronal images, clearly showed basal cerebral moyamoya vessels in 54 hemispheres, and 45 of a total of 71 large leptomeningeal and transdural collateral vessels were identified. MRI also showed parenchymal lesions in 48 (80%) hemispheres, and the extent of occlusion in the anterior and posterior circulations respectively correlated with white matter and cortical and/or subcortical infarcts.     

Zonal frequency analysis of infarct extent. Part II: anterior and posterior cerebral artery infarctions

The object of the study was to test the hypotheses that analysis of the anatomic zones affected by single anterior (A), posterior (P), and middle (M) cerebral artery (CA) infarcts, and by dual- and triple-vessel infarcts, will disclose (i) sites most frequently involved by each infarct type (peak sites), (ii) sites most frequently injured by multiple different infarct types (vulnerable zones), and (iii) anatomically overlapping sites in which the relative infarct frequency becomes equal for two or more different infarct types and/or in which infarct frequency shifts greatly between single and multivessel infarcts (potential border zones). Precise definitions of each vascular territory were adopted. CT and MRI studies from 20 ACA, 20 PCA, three dual ACA-PCA, and four triple ACA-PCA-MCA infarcts were mapped onto a standard template (Part I). Relative infarct frequencies in each zone were analyzed within and across infarct types to identify the centers and peripheries of each infarct type, the zones most frequently affected by multiple different infarct types, the zones where relative infarct frequency was equal for different infarcts, and the zones where infarct frequency shifted markedly from single- to multiple-vessel infarcts. Zonal frequency analysis provided quantitative data on the relative infarct frequency in each anatomic zone for each infarct type. It displayed zones of peak infarct frequency for each infarct, zones more vulnerable to diverse types of infarct, peripheral "overlap" zones of equal infarct frequency, and zones where infarct frequency shifted markedly between single- and multiple-vessel infarcts. It is concluded that the hypotheses are correct.     

Focal inflammation in the embryological ventral pancreas: assessment using CT and MRI

AIM: To identify the characteristic computed tomography (CT) and magnetic resonance imaging (MRI) findings of nonuniform inflammation between the posterior aspect of the head and the remainder of the pancreas. MATERIALS AND METHODS: Two radiologists retrospectively evaluated images of 19 patients in whom the degree of attenuation in the CT images and/or the signal intensity in the MRI images differed between the posterior aspect of the head (ventral primordium) and the remainder of the pancreas (dorsal primordium) due to benign disorders other than uneven fatty replacement. Multiphase, contrast-enhanced CT examinations were performed in 17 patients. In five, T1- and T2-weighted images with and without fat suppression were obtained using a 1.5 T superconducting MRI system. RESULTS: The lesions were localized in the posterior aspect of the head in 17 patients. In two patients, the lesions occupied the posterior aspect of the head and extended to the neck. The lesions exhibited the following findings: inhomogeneous hypoattenuation (with spotty areas of relatively well-maintained contrast enhancement) during the pancreatic phase (17/17) and no intense peripheral enhancement or central necrotic areas (17/17) in CT images, hypointensity in T1-weighed images (5/5), hyperintensity in T2-weighed images (4/5), no vascular invasion (19/19), failure to depict the entire course of Wirsung's duct (17/19), and calcification (13/19). Santorini's ducts were depicted in all but three patients. CONCLUSION: Focal inflammation in the embryological ventral pancreas exhibits a unique anatomical distribution and characteristic findings.     

CT and MR imaging features of oral and maxillofacial hemangioma and vascular malformation

PURPOSE: To present CT and MR images and compare CT and MRI features of oral and maxillofacial hemangioma and vascular malformation. MATERIAL AND METHODS: The clinical materials consisted of nine vascular tumors from nine patients examined by both CT and MR scanners between November 1996 and March 2002. Both CT and MR images were retrospectively evaluated. The following features were evaluated: detectability of the lesion, border of the lesion, tumor margin, inner nature of the lesion, contrast between the lesion and surrounding tissues, degree of CT value or signal intensity of the lesion, enhancement of contrast medium, inner nature of the lesion after contrast medium injection, detectability of phleboliths and detectability of bone resorption. RESULTS: In two patients, we could not detect lesions in any of the CT images because of artifacts from the teeth and/or dental restorations. In contrast, we could detect all lesions on T2-weighted MR images and contrast enhanced T1-weighted MR images. On T2-weighted images with the fat suppression technique, tumors tended to show higher contrast compared to surrounding tissues. CONCLUSION: T2-weighted images with the fat suppression technique and contrast enhanced T1-weighted images with the fat suppression technique were very useful for the detection of vascular lesions. Observation from optional directions (axial, coronal and sagittal images) seemed appropriate for delineating the extension of the tumor. Phleboliths detectability on CT images was superior to that on MR images.     

Semicircular canal dehiscence: comparison of T2-weighted turbo spin-echo MRI and CT

We assessed the value of MRI for delineation of dehiscence of the superior or posterior semicircular canal, as compared with CT, the current standard study for this entity. We reviewed heavily T2-weighted fast spin-echo images and high-resolution CT of the temporal bones of 185 patients independently semicircular canal dehiscence and its extent. In 30 patients (19 men, 11 women) we identified dehiscence of the bone over the superior and/or posterior semicircular canal on MRI. In 27 of these cases CT also showed circumscribed bone defects. In one patient dehiscence of the superior semicircular canal was initially overlooked on MRI, but seen on CT. MRI imaging thus had a sensitivity of 96% and specificity of 98%. Knowledge of the appearances of this entity on MRI may contribute to early diagnosis in patients with vertigo due to semicircular canal dehiscence.     

Imaging features of posterior fossa neoplasms in children and adults

Masses in the posterior fossa may be divided into extra-axial and intra-axial lesions. Because of its multiplanar capabilities, improved soft-tissue resolution and contrast, and the absence of scanning artifacts related to the osseous skull base, which are frequently present on CT, MRI is the imaging modality of choice in evaluating lesions arising in the posterior fossa. It is the best means of critically localizing lesions and determining the extent of disease. Analysis of the signal characteristics of a lesion on multiple different imaging sequences (T1-weighted, T2-weighted, and enhanced images) may provide information about the tissue constituents within a mass/neoplasm, such as the presence of cellularity, necrosis, and hemorrhage. MRI is also useful in guiding localization for brain tumor biopsies and assists in planning radiation therapy. However, CT also plays an important role. CT is frequently the first imaging study performed in patients with posterior fossa masses who often present with nausea, vomitting, ataxia, and other signs of increased intracranial pressure. It is a quick, available, and relatively inexpensive study to assess neurological emergencies including hydrocephalus, hemorrhage, and herniation syndromes. In addition, it frequently provides complimentary information, such as the presence of calcification or bony remodeling (osteosclerosis or osteolysis), which MRI is less sensitive in detecting.     

Histologic breast cancer extent after neoadjuvant chemotherapy: comparison with multidetector-row CT and dynamic MRI

PURPOSE: To evaluate the efficacy of dynamic multidetector-row CT (MDCT) in assessing residual cancer extent after neoadjuvant chemotherapy (NAC), and to compare MDCT results with those derived from dynamic three-dimensional MRI using the volumetric interpolated breath-hold examination (VIBE) sequence. MATERIALS AND METHODS: MDCT before and after NAC was performed in 19 consecutive patients with breast cancer. MRI was also performed before surgery. The early phase of MDCT and MRI was started 60 sec after commencing contrast injection. The late phase was started at a 4-min delay from the injection. The injection rate was 3 mL/sec. The distribution pattern of contrast enhancement (CE) by CT before NAC was classified into two groups: replaced lesion (diffuse CE in whole quadrants) and non-replaced lesion (localized CE). RESULTS: Pathological complete response (pCR) was obtained in one case. In replaced lesions, accuracy for the detection of tumor extent with a deviation of less than 2 cm in length was 0% (0/7) with early-phase CT/MRI and 100% (7/7) with late-phase CT/MRI. In non-replaced lesions, accuracy was 55% (6/11) with early-phase CT/MRI and 82% (9/11) with late-phase CT/MRI. One case of ductal carcinoma in situ (DCIS) could be detected only with late phase MRI. CONCLUSION: Late-phase images obtained by MDCT and MRI may be accurate in the diagnosis of residual cancer extent after NAC. The tumor distribution determined by MDCT before NAC is thought to be useful in the evaluation of shrinkage pattern following NAC.     

Role of magnetic resonance in the radiologic diagnosis of parotid pathology

MRI findings in 13 patients with monolateral parotid tumor were compared with US, sialographic and CT findings. MRI did not allow an accurate diagnosis in 2 patients with diffuse chronic parotitis. MRI was superior to CT in 1 case in defining the intraglandular site of the lesion, and in 2 patients in showing the extraglandular involvement. MRI proved to be superior to CT thanks to its contrast resolution and to multiplanar imaging. MRI high contrast resolution made it possible to demonstrate neoplastic lesions of 4 mm in diameter. The lesion has low signal intensity on T1-weighted images and high signal intensity on T2-weighted. Parotid tumors cannot be characterized by signal intensity alone: only morphology allows to discriminate between benign and malignant lesions. To conclude, US is a screening method, while MRI is helpful in detecting multifocal lesions and in evaluating the tumor extent.     

Serial CT and MRI of ischaemic cerebral infarcts: frequency and clinical impact of haemorrhagic transformation

The frequency, predisposing factors and clinical consequences of haemorrhagic infarcts and damaged blood-brain barrier as shown by contrast enhancement (CE) in ischaemic cerebral infarcts are controversial. We prospectively compared the sensitivity of CT and MRI to haemorrhagic transformation (HT) and CE. We also wished to investigate the clinical significance of HT and factors possibly associated with it. We studied 36 patients with acute ischaemic infarcts in the middle cerebral artery territory during the first 2 weeks after the ictus. After CT and rating of the neurological deficit on admission, serial examinations with clinical neuromonitoring, contrast-enhanced CT and MRI were done on the same day. The occurrence and severity of HT were correlated with CE, stroke mechanism, infarct size, development of neurological deficits and antithrombotic treatment. The frequency of HT detected by MRI was 80 %. CE usually preceded HT or was seen simultaneously. MRI had a higher sensitivity than CT to HT and CE. Severity of HT was positively correlated with infarct size (P < 0.01). HT had no influence on patient's neurological status. Neither the type of antithrombotic treatment nor the stroke mechanism was associated with the severity of HT. No parenchymal haemorrhage occurred. Received: 10 November 1998 Accepted: 29 July 1999     

节细胞神经瘤的影像诊断及病理分析

目的探讨CT及MRI在诊断节细胞神经瘤中的价值,旨在提高诊断的准确率。方法收集并分析30例节细胞神经瘤患者的CT及MRI影像与临床资料,并与病理结果进行对照。结果29例为单发病灶,另1例位于颈1/2椎管内病灶为双侧发病。后纵隔12例,椎管内外5例,后腹膜3例,肾上腺8例,淋巴结2例。CT平扫呈均匀或不均匀性低密度影,低于邻近肌肉密度,增强扫描动脉期病灶轻度强化或无强化,静脉期及延迟期可见持续性不均匀强化。6例肿瘤内见弧形、斑点状钙化。MRI平扫T1WI呈低信号,T2WI呈稍高/高信号为主,增强后呈轻至中度渐进性强化。结论节细胞神经瘤的CT和MRI表现具有一定特征性。当发生于后纵隔、腹膜后、肾上腺、椎管内外及淋巴结等部位时又具有相对的特异性,了解这些共性与个性,对进一步提高该病诊断的准确性非常有价值。