Telangiectatic focal nodular hyperplasia: US,CT, and MR imaging findings with histopathologic correlation in 13 cases

PURPOSE: To review the ultrasonographic (US), computed tomographic (CT), and magnetic resonance (MR) imaging findings in 13 patients with telangiectatic focal nodular hyperplasia (FNH) and to compare imaging features with histopathologic results from resected specimens. MATERIALS AND METHODS: US, helical multiphasic CT, and MR images in 13 patients with pathologically proven telangiectatic FNH were reviewed retrospectively. Two abdominal radiologists evaluated lesions for number, size, heterogeneity, surface characteristics, presence of a central scar, presence of a pseudocapsule, US appearance, attenuation at CT, signal intensity at MR imaging, and presence of associated lesions. Imaging and pathologic findings were compared. RESULTS: Sixty-one lesions (5-140 mm in diameter) were seen at imaging. Lesions were multiple in eight of 13 (62%) patients. Imaging characteristics were heterogeneity in 26 of 61 lesions (43%), well-defined margins in 43 of 61 (70%), lack of a central scar in 56 of 61 (92%), presence of a pseudocapsule in three of 61 (5%), hyperintensity on T1-weighted MR images in 17 of 32 (53%), strong hyperintensity on T2-weighted MR images in 24 of 54 (44%), and persistent enhancement on delayed contrast material-enhanced CT or T1-weighted MR images in 23 of 38 (61%). No specific US pattern was noted. Two patients had additional lesions: One had classic FNH, and the other had a cavernous hemangioma. Hyperintensity on T1-weighted MR images was due to sinusoidal dilatation. Hyperintensity on T2-weighted MR images correlated well with the presence of inflammation. CONCLUSION: Telangiectatic FNH differs from typical FNH at imaging: Atypical FNH features often observed with telangiectatic FNH are lack of a central scar, lesion heterogeneity, hyperintensity on T1-weighted MR images, strong hyperintensity on T2-weighted MR images, and persistent contrast enhancement on delayed contrast-enhanced CT or T1-weighted MR images.     

The variable MR appearance of primary lymphoma of the central nervous system: comparison with histopathologic features.

PURPOSETo describe the MR features of primary central nervous system (CNS) lymphoma and to determine whether there is a correlation with histopathologic findings.METHODSThe MR images, pathologic specimens, and clinical records of 23 patients with primary CNS lymphoma were reviewed. The imaging and pathologic characteristics were tabulated and compared by using the standard tests for association in a two-dimensional contingency table.RESULTSA total of 61 lesions were present in 23 patients; 12 patients (52%) had multiple lesions. All lesions were isointense or hypointense on T1-weighted images, and 53% were isointense or hypointense on T2-weighted images. Twenty patients received intravenous contrast material, and 43 (91%) of 47 lesions enhanced. The three patients who had nonenhancing lesions received steroids before the initial MR studies. Enhancement patterns differed between the immunocompetent and the immunocompromised hosts, with the latter group harboring a higher percentage of rim-enhancing lesions. Twenty-seven (44%) of the lesions were centered in a cerebral hemisphere and 14 (23%) were centered in the central gray matter. There was a statistically significant correlation between a higher degree of necrosis histologically and hyperintensity on T2-weighted MR images. The degree of necrosis also showed a positive correlation with rim enhancement.CONCLUSIONSPrimary CNS lymphoma has a variable MR appearance that correlates with the severity of intratumoral necrosis. These imaging characteristics, as well as lesion location, mean lesion size, and proclivity to harbor necrosis, are altered in the immunocompromised host.     

Encephalitis caused by human immunodeficiency virus: CT and MR imaging manifestations with clinical and pathologic correlation

To determine the computed tomographic (CT) and magnetic resonance (MR) imaging manifestations of central nervous system (CNS) infection by the human immunodeficiency virus (HIV), the authors analyzed the results of imaging of the CNS in 24 patients with HIV encephalitis confirmed at autopsy. Careful pathologic correlation demonstrated that neither CT nor MR imaging enabled detection of microglial nodules with multinucleated giant cells, the hallmark of HIV encephalitis seen in all 24 affected patients. The most common abnormality observed on images of the CNS was atrophy, demonstrated in 18 patients. Demyelination and vacuolation of white matter tracts accompanying severe HIV infection caused hypoattenuation on CT scans and hyperintensity on T2-weighted MR images. These lesions had no mass effect. MR imaging was more sensitive than CT in the detection of lesions caused by HIV or other superimposed infectious agents. Although it is often difficult to attribute any radiologic appearance to a single etiologic agent in patients with acquired immunodeficiency syndrome, the combination of atrophy and symmetric, periventricular or diffuse white matter disease suggests HIV encephalitis.     

Diffusion-weighted MR imaging of Carmofur-induced leukoencephalopathy

Carmofur (1-hexylcarbamyl-5-fluorouracil), a derivative of 5-fluorouracil (5-FU), has been widely used in Japan as a postoperative adjuvant chemotherapy agent for colorectal and breast cancer. Periventricular hyperintensity on T2-weighted MR images in carmofur-induced leukoencephalopathy confront the physician with a broad range of differential diagnoses. We describe two cases of carmofur-induced leukoencephalopathy in which diffusion-weighted MR imaging revealed periventricular hyperintensity. We compared their findings with those of age-related periventricular hyperintensity in five patients and found discrepancies in signal intensity of periventricular areas. Our results suggest that diffusion-weighted MR imaging may be useful to differentiate carmofur-induced leukoencephalopathy from age-related periventricular hyperintensity.     

Invasive pulmonary aspergillosis: evaluation with MR imaging

Eleven patients with suspected invasive pulmonary aspergillosis underwent magnetic resonance (MR) imaging. Images were obtained with standard spin-echo sequences and electrocardiographic triggering before and after intravenous administration of gadolinium diethylenetriaminepentaacetic acid. Thirty-seven of 48 lesions seen on MR images were nodular infiltrates; 34 of these had a targetlike appearance, with hypointense centers and iso- or hyperintense rims. Twenty-three of 37 nodular lesions contained areas of hyperintensity on T1-weighted images. All 37 had enhanced rims on postcontrast MR images. The remaining 11 lesions were segmental infiltrates, seven of which were predominantly hyperintense on T1-weighted images. In one patient with nodular lesions, MR imaging findings were correlated with those from pathologic analysis of a resected upper lobe. Areas of hyperintensity corresponded to subacute hemorrhage permeated by Aspergillus organisms. The authors believe that the typical targetlike appearance of nodular lesions on MR images and the potential that MR imaging has to reveal hemorrhagic content will prove useful in the early diagnosis of invasive pulmonary aspergillosis.     

Structural, immunocytochemical, and mr imaging properties of periventricular crossroads of growing cortical pathways in preterm infants

BACKGROUND AND PURPOSE: Periventricular white matter (WM) areas are widely recognized as predilection sites for complex cellular damage after ischemia/reperfusion or inflammatory injury of the perinatal cerebrum. We analyzed histochemical and MR imaging properties of fiber architectonics and extracellular matrix (ECM) of periventricular areas to disclose the potential significance of topographically specific WM lesions for the neurodevelopmental outcome. METHODS: We combined histochemical methods for demonstration of fibers, axonal guidance molecules, and ECM with T1-weighted MR images on postmortem specimens aged 15 to 36 postovulatory weeks (POW) and T2-weighted MR images on in vivo fetuses aged 14 to 26 POW. RESULTS: The fiber architectonics of the fetal cerebrum display tangential axon strata in frontopolar and occipitopolar regions, whereas the central periventricular region contains crossroads of intersecting callosal (transverse), associative (sagittal), and thalamocortical/corticofugal (radial) fiber bundles. In early preterms, crossroads contain hydrophylic ECM with axonal guidance molecules, and they are easily recognized as hypointensities on T1-weighted MR images or hyperintensities on T2-weighted MR images. After the 28 POW, tangential fetal fiber-architectonic stratification transforms into the corona radiata system; however, the growth of cortical pathways continues in crossroad areas, as indicated by the presence of ECM and their distinct MR imaging signal intensities. CONCLUSIONS: The correlation of MR imaging with histochemical findings demonstrated the presence of periventricular fiber crossroads rich in ECM and axonal guidance molecules. We propose that, in perinatal WM lesions, periventricular WM crossroads represent a hitherto unrecognized and vulnerable cellular and topographic target in which combined damage of association-commissural and projection fibers may explain the complexity of cognitive, sensory, and motor deficit in survivors of periventricular WM lesions.     

Delayed encephalopathy of acute carbon monoxide intoxication: diffusivity of cerebral white matter lesions

BACKGROUND AND PURPOSE: Carbon monoxide intoxication has delayed effects on the cerebral white matter characterized by bilateral, confluent lesions that reflect diffuse demyelination. To increase our understanding of this process, we assessed the diffusion characteristics of these lesions. METHODS: Five consecutive patients with delayed encephalopathy of CO intoxication were examined with diffusion MR imaging. Diffusion-weighted images (DWIs) were obtained 25-95 days after their exposure to CO and during a relapse of neuropsychiatric symptoms, which occurred after an initial recovery. Imaging was performed at 1.5 T by using a spin-echo echo-planar sequence with diffusion gradients of 0, 500, and 1000 s/mm(2). DWIs and apparent diffusion coefficient (ADC) maps were visually evaluated, and mean ADCs were calculated from the periventricular white matter and the centrum semiovale, where confluent hyperintensity was seen on T2-weighted images. Findings were compared with those of normal-looking white matter. RESULTS: In all five patients, both T2-weighted images and DWIs showed the white matter lesions as bilateral, diffuse, confluent areas of hyperintensity in the periventricular white matter and centrum semiovale. On ADC maps, these lesions were isointense, with focal areas of hypointensity (n = 4) or diffuse hypointensity (n = 1). Mean ADC values of the white matter lesions were significantly lower than those of normal-looking white matter, regardless of their isointensity or hypointensity on ADC maps (P <.05). CONCLUSION: Bilateral, confluent, white matter lesions in patients with delayed encephalopathy of CO intoxication show decreased diffusivity.     

Cerebral visual impairment in periventricular leukomalacia: MR correlation.

PURPOSETo evaluate the involvement of central visual pathways in cases of periventricular leukomalacia, and to correlate the neuroradiologic findings with the degree of visual acuity.METHODSThe MR brain examinations of 27 preterm children affected by cerebral palsy resulting from periventricular leukomalacia and without significant ophthalmologic lesions were reviewed retrospectively to search for possible involvement of the optic radiations and/or of the calcarine cortex. The data were compared with the degree of visual acuity estimated by means of the Teller Acuity Cards test.RESULTSSeventeen (63%) of the 27 patients had cerebral visual impairment, which correlated strongly with MR lesions. Quantitative reduction and signal hyperintensity of the peritrigonal white matter and atrophy of the calcarine cortex were present in the more severe cases. In two blind patients, an altered MR signal was detected in the lateral geniculate bodies.CONCLUSIONThis study clearly establishes a relationship between specific MR findings and visual impairment in children with periventricular leukomalacia. The finding of hyperintensity in the lateral geniculate bodies was interpreted as an axonal reaction. MR imaging is useful for detecting potential visual impairment and for improving clinical diagnosis.     

Whipple disease confined to the central nervous system in childhood.

In a case of pediatric Whipple disease confined to the central nervous system, white matter lesions initially appeared as areas of very low signal intensity on T1-weighted MR images and as areas of hyperintensity on proton density-weighted and T2-weighted images, and showed slight peripheral enhancement on delayed contrast-enhanced T1-weighted images. On MR studies obtained 3 and 6 months after antibiotic therapy, the lesions had decreased in size and no longer enhanced. They became progressively less hypointense on T1-weighted images and less hyperintense on T2-weighted images.     

Abnormal hyperintensity within the subarachnoid space evaluated by fluid-attenuated inversion-recovery MR imaging: a spectrum of central nervous system diseases

A variety of central nervous system (CNS) diseases are associated with abnormal hyperintensity within the subarachnoid space (SAS) by fluid-attenuated inversion-recovery (FLAIR) MR imaging. Careful attention to the SAS can provide additional useful information that may not be available with conventional MR sequences. The purpose of this article is to provide a pictorial essay about CNS diseases and FLAIR images with abnormal hyperintensity within the SAS. We present several CNS diseases including subarachnoid hemorrhage, meningitis, leptomeningeal metastases, acute infarction, and severe arterial occlusive diseases such as moya-moya disease. We also review miscellaneous diseases or normal conditions that may exhibit cerebrospinal fluid hyperintensity on FLAIR images. Although the detection of abnormal hyperintensity suggests the underlying CNS diseases and narrows differential diagnoses, FLAIR imaging sometimes presents artifactual hyperintensity within the SAS that can cause the misinterpretation of normal SAS as pathologic conditions; therefore, radiologists should be familiar with such artifactual conditions as well as pathologic conditions shown as hyperintensity by FLAIR images. This knowledge is helpful in establishing the correct diagnosis.     

MR imaging of optic pathways in patients with neurofibromatosis

Twenty-one patients with documented neurofibromatosis had MR examinations to evaluate possible intracranial disease. In five cases the indication was a known or suspected optic glioma. Two patients were examined because of a history of seizures; the rest were examined as part of a baseline evaluation. Eighteen patients showed evidence of signal hyperintensity on T2-weighted images. Lesions involved the optic nerves, optic chiasm, optic tracts, lateral geniculate body, optic radiations, basal ganglia, periventricular white matter, cerebellar white matter, and dentate nucleus of the cerebellum. Comparison between MR and concurrent CT scans showed MR to be superior in demonstrating the posterior extent of optic-pathway gliomas. In addition, MR showed focal areas of hyperintensity in the basal ganglia, internal capsule, cerebellum, and/or white matter that were not detected on CT. Although we found MR to be superior to CT in detecting intracranial tumors in patients with neurofibromatosis, and in evaluating the extensive involvement of known lesions, the full clinical implications of our findings remain to be determined.     

Abnormal hyperintensity within the subarachnoid space evaluated by fluid-attenuated inversion-recovery MR imaging: a spectrum of central nervous system diseases

A variety of central nervous system (CNS) diseases are associated with abnormal hyperintensity within the subarachnoid space (SAS) by fluid-attenuated inversion-recovery (FLAIR) MR imaging. Careful attention to the SAS can provide additional useful information that may not be available with conventional MR sequences. The purpose of this article is to provide a pictorial essay about CNS diseases and FLAIR images with abnormal hyperintensity within the SAS. We present several CNS diseases including subarachnoid hemorrhage, meningitis, leptomeningeal metastases, acute infarction, and severe arterial occlusive diseases such as moyamoya disease. We also review miscellaneous diseases or normal conditions that may exhibit cerebrospinal fluid hyperintensity on FLAIR images. Although the detection of abnormal hyperintensity suggests the underlying CNS diseases and narrows differential diagnoses, FLAIR imaging sometimes presents artifactual hyperintensity within the SAS that can cause the misinterpretation of normal SAS as pathologic conditions; therefore, radiologists should be familiar with such artifactual conditions as well as pathologic conditions shown as hyperintensity by FLAIR images. This knowledge is helpful in establishing the correct diagnosis.

     

Benign hepatic nodules in Budd-Chiari syndrome: radiologic-pathologic correlation with emphasis on the central scar

OBJECTIVE: The purpose of this study was to determine the imaging features of benign hepatic nodules in patients with Budd-Chiari syndrome and to correlate them with pathologic findings, with special attention placed on the presence of a central scar. MATERIALS AND METHODS: Imaging findings of 59 benign hepatic nodules in four patients with chronic Budd-Chiari syndrome were analyzed retrospectively, and radiologic- pathologic correlation was performed in three patients with 50 hepatic nodules who underwent liver transplantation. All patients underwent multiphasic helical CT. In three patients with 29 lesions, MR imaging, including a multiphasic dynamic study, was performed. The CT and MR imaging findings in these patients were compared with those of 103 small hepatocellular carcinomas in 56 other patients (54 of them displayed chronic hepatitis or liver cirrhosis associated with viral hepatitis but none had Budd-Chiari syndrome). Image analysis was performed by two radiologists with no knowledge of the diagnosis. RESULTS: All patients with Budd-Chiari syndrome exhibited multiple benign nodules up to 3 cm in diameter, and 42 of 59 lesions were hypervascular. Microscopically, 15 of 32 nodules demonstrated a central scar; moreover, some nodules closely resembled focal nodular hyperplasia. Frequencies of hyperintensity on T1-weighted images (14/29 vs 25/103), hypointensity on T2-weighted images (7/29 vs 1/103), and the presence of a central scar (6/59 vs 1/103) were significantly higher in benign nodules than in hepatocellular carcinomas (p < 0.05; Fisher's exact test). Moreover, for lesions larger than 1 cm, imaging studies revealed a central scar in six of 15 benign lesions. CONCLUSION: Benign hepatic nodules in patients with in Budd-Chiari syndrome are usually small, multiple, and hypervascular. The presence of a central scar is a characteristic feature in those larger than 1 cm in diameter.     

非酒精性Wernicke脑病临床特点及MRI表现

目的探讨非酒精性Wernicke脑病(WE)病人临床特点及MRI表现。方法回顾性分析经临床证实的10例非酒精性WE病人临床特点及MRI表现。结果胃肠道疾病所致反复呕吐、急性胰腺炎及妊娠剧烈呕吐为主要发病诱因。精神或意识改变为最常见临床表现。10例病人中仅1例为单发病灶,余9例均为多部位受累,病变部位包括双侧丘脑内侧及三脑室周围区(8例)、中脑导水管周围区(7例)、中脑顶盖(6例)、乳头体(4例)、四脑室底(4例)、小脑蚓部(1例)。所有病灶均于T2WI或T2FLAIR上呈对称性高信号。8例行DWI扫描,病灶呈高或稍高信号。1例行MRI增强检查,病灶呈轻度强化。4例于治疗后复查颅脑MRI,均见病灶缩小或消失。结论非酒精性WE的颅脑MRI表现具有特征性,结合病史及临床表现有助于做出早期诊断。     

Magnetization transfer imaging of periventricular hyperintense white matter in the elderly.

PURPOSETo characterize with magnetization transfer imaging the pathologic substrate of the nonspecific periventricular hyperintense white matter changes seen on T2-weighted images of elderly patients.METHODSTwenty-one elderly patients with periventricular hyperintense white matter on T2-weighted MR images and eleven control subjects were studied using MT technique. Magnetization transfer ratios (MTRs) were calculated for the periventricular hyperintense white matter and normal-appearing white matter. These MTRs were correlated with histopathologic changes that have previously been reported as well as with established MTRs for other lesions.RESULTSThe MTRs (mean, 35.2; SD, 1.2) in the periventricular hyperintense white matter are lower than those in the normal white matter of the patient (mean, 40.8; SD, 1.4) and control (mean, 41.3; SD, 1.8) groups. These MTRs are much higher than those of demyelinating lesions but are similar to those of experimental lesions with just edema.CONCLUSIONBecause MTR may reflect to some extent histopathologic changes and thus provide more specificity than conventional pulse sequences, the main pathologic substrate accounting for the lower MTR in periventricular hyperintense white matter is probably the increased water content in reactive astrocytes.     

Chondroblastoma: MR characteristics with pathologic correlation.

PURPOSE: The purpose of this study was to describe the MR findings of chondroblastoma with pathologic correlation. METHOD: In 22 patients with pathologically proven chondroblastoma, MR signal characteristics were correlated with pathological findings. RESULTS: On T2-weighted images, 12 (55%) lesions were hyperintense with hypointense areas in 9 lesions, whereas 10 (45%) were hypointense. Therefore, 19 of 22 (86%) lesions with pathologic correlation had hypointense areas entirely (n = 10) or partly (n = 9) on T2-weighted images. On gadolinium-enhanced images, 13 (59%) lesions showed lobular enhancement and 9 (41%) showed marginal and septal enhancement. Low signal intensity on T2-weighted MR images was most strongly associated with an abundance of immature chondroid matrix, hypercellularity of the chondroblasts, calcifications, and hemosiderin on histology. CONCLUSION: Chondroblastoma was found to show hypointense portions on T2-weighted images. Signal intensity on T1- and T2-weighted MR images in chondroblastoma was dependent on the amounts of histopathological components.     

MR of childhood-onset dentatorubral-pallidoluysian atrophy.

MR findings in a 14-year-old boy with progressive myoclonic epilepsy, who was diagnosed as having dentatorubral-pallidoluysian atrophy by DNA analysis, were compared with those of his father, who had adult-onset dentatorubral-pallidoluysian atrophy. Besides showing severe brain atrophy, especially of the brain stem tegmentum and cerebellum, MR showed diffuse periventricular hyperintensity on T2-weighted images. As compared with the proband, the father had a mild case.     

Patellar articular cartilage lesions: in vitro MR imaging evaluation after placement in gadopentetate dimeglumine solution

PURPOSE: To evaluate T1-weighted magnetic resonance (MR) imaging after diffusion of gadopentetate dimeglumine for visualization of articular cartilage lesions. MATERIALS AND METHODS: MR imaging was performed in eight human cadaveric patella specimens immediately and 4 hours after placement into a vessel filled with gadopentetate dimeglumine solution (2.5 mmol/L). T1-weighted spin-echo and inversion-recovery turbo spin-echo MR sequences with nulled cartilage signal (inversion time of 300 msec) were used. In a total of 128 articular cartilage areas, MR imaging findings were compared with macroscopic and histopathologic findings. Pathologic evaluation was performed by one musculoskeletal pathologist. With knowledge of pathologic observations, MR images were analyzed by one musculoskeletal radiologist with regard to intrinsic signal intensity characteristics and surface abnormalities of articular cartilage. RESULTS: Histopathologic findings demonstrated 67 areas of normal articular cartilage and 66 cartilage lesions (grade 1, n = 19; grade 2, n = 15; grade 3, n = 26; grade 4, n = 6). All grade 3 and 4 lesions could be identified on MR images obtained immediately after submersion and after 4 hours. Ninety-four percent of grade 1 and 2 lesions were identified as areas of predominantly decreased contrast enhancement on delayed MR images obtained with both sequences. MR images obtained immediately after submersion demonstrated abnormal signal intensity in only 9% and 12% of grade 1 and 2 lesions, respectively. CONCLUSION: T1-weighted MR images obtained in vitro after gadopentetate dimeglumine diffusion allow demonstration of articular cartilage surface lesions and early stages of cartilage degradation.     

Primary central nervous system lymphoma versus toxoplasmosis in AIDS

The imaging studies of 16 patients with acquired immunodeficiency syndrome (AIDS) and proved primary central nervous system (CNS) lymphoma were reviewed. All studies included computed tomography (CT); six also included magnetic resonance (MR) imaging. A periventricular lesion was seen in 50% of patients. At least one such lesion exhibited subependymal spread or ventricular encasement in 38%. One-third of lesions in three of five patients who underwent nonenhanced CT were hyperattenuating. Five lesions were at least in part hypointense on T2-weighted MR images. The specificity of these findings was evaluated with a similar review of the imaging studies in 28 patients with AIDS and proved toxoplasmosis. Only 3% of lesions were periventricular. None exhibited subependymal spread or encasement. None were hyperattenuating on nonenhanced CT scans. Similar findings in other CNS lesions in AIDS patients could not be found in the literature. A focal enhancing mass with subependymal spread on CT or MR images and hyperattenuation at nonenhanced CT were the most reliable features in distinguishing between primary CNS lymphoma and toxoplasmosis in AIDS patients.     

Multiple sclerosis: serial study of gadolinium-enhanced MR imaging

Thirteen patients with definite multiple sclerosis (MS), studied 16-24 months previously with magnetic resonance (MR) imaging with and without enhancement by intravenously administered gadolinium diethylenetriaminepentaacetic acid (DTPA) dimeglumine, were reexamined with a similar protocol. Assessment of enhancement and clinical activity in both studies revealed that enhancement was observed in 13 of 14 cases in which clinical activity had changed within 4 weeks of the study and thus appeared more sensitive than clinical examination in determining active disease. The 3-minute postinjection, short repetition time image (TR) was the most efficient for depicting enhancement. Enhancing lesions (active plaques) arose from previously hyper- or isointense regions on long TR images. Previously active lesions reverted to areas of iso- or hyperintensity on long TR images. Serial comparison of long TR images in this population reveals a decrease in high-intensity lesions on long TR images in some cases and an increase in others. The findings of high-intensity regions on long TR images and previously enhancing lesions both becoming isointense suggests that transient inflammatory changes with concomitant edema without demyelination and/or with significant remyelination may occur in some MS lesions. MS lesions are dynamic; both active and inactive lesions may show dramatic change on longitudinal MR imaging studies.