MR Imaging Signal Intensity Research Articles

Chitosan-modified manganese oxide-conjugated methotrexate nanoparticles delivering 5-aminolevulinic acid as a dual-modal T1-T2* MRI contrast agent in U87MG cell detection.

Glioblastoma multiforme is a highly aggressive form of brain cancer, and early diagnosis plays a pivotal role in improving patient survival rates. In this regard, molecular magnetic resonance imaging has emerged as a promising imaging modality due to its exceptional sensitivity to minute tissue changes and the ability to penetrate deep into the brain. This study aimed to assess the efficacy of a novel contrast agent in detecting gliomas during MRI scans. The contrast agent utilized modified chitosan coating on manganese oxide nanoparticles. The modification included adding methotrexate and 5-aminolevulinic acid (MnO2/CS@5-ALA-MTX) to target cells with overexpressed folate receptors and breaking down excess hydrogen peroxide in tumor tissue, resulting in enhanced signal intensity in T1-weighted MR images but diminished signal intensity in T2*-weighted MR images. The nanosystem was characterized and evaluated in MR imaging, safety, and ability to target cells both in vivo and in vitro. MTX-free nanoparticles (MnO2/CS@5-ALA NPs) had no obvious cytotoxicity on cell lines U87MG and NIH3T3 after 24/48 h at a concentration of up to 160 µgr/mL (cell viability more than 80%). In this system, methotrexate enables tumor targeting and the MnO2/5-ALA improves T1-T2*-weighted MRI. In addition, MRI scans of mice with M109 carcinoma indicated significant tumor uptake and NP capacity to improve the positive contrast effect. This developed MnO2/CS@5-ALA-MTX nanoparticle system may exhibit great potential in the accurate diagnosis of folate receptor over-expressing cancers such as glioblastoma.

Leukocoria in Children: Findings on CT and MRI of the Principal Causes

Leukocoria is the result of an alteration in the normal red reflex of the ocular fundus, secondary to an obstruction of the normal passage of light to the fundus of the eye that produces a white light reflex. There are many ocular pathologies that can present as leukocoria, among which retinoblastoma is the most frequent. Other causes include cataracts, Coats disease, persistent fetal vasculature, coloboma, retinopathy of prematurity, vitreous hemorrhage, astrocytic hamartoma, and ocular toxocariasis. Although in many situations the diagnosis of these pathologies is clinical or possible with the use of ocular sonography, in certain circumstances, CT or MR imaging may play a very important role in the differential diagnosis. In this review article, we propose that findings such as ocular size, the presence of calcifications, intravenous contrast enhancement, MR imaging signal intensity, CT density, and other pathology-specific findings, along with some clinical data, will guide us to the cause of leukocoria. Knowledge of the most prevalent ages of presentation of these pathologies assists with establishing the final diagnosis.Learning Objectives: To understand why leukocoria occurs, to list the major causes of leukocoria in children, and to recognize the imaging findings of the most frequent causes of leukocoria and apply them in the differential diagnosis

Mapping Human Fetal Brain Maturation In Vivo Using Quantitative MRI.

On the basis of a single multidynamic multiecho sequence acquisition, SyMRI generates a variety of quantitative image data that can characterize tissue-specific properties. The aim of this retrospective study was to evaluate the feasibility of SyMRI for the qualitative and quantitative assessment of fetal brain maturation. In 52 fetuses, multidynamic multiecho sequence acquisitions were available. SyMRI was used to perform multidynamic multiecho-based postprocessing. Fetal brain maturity was scored qualitatively on the basis of SyMRI-generated MR imaging data. The results were compared with conventionally acquired T1-weighted/T2-weighted contrasts as a standard of reference. Myelin-related changes in T1-/T2-relaxation time/relaxation rate, proton density, and MR imaging signal intensity of the developing fetal brain stem were measured. A Pearson correlation analysis was used to detect correlations between the following: 1) the gestational age at MR imaging and the fetal brain maturity score, and 2) the gestational age at MR imaging and the quantitative measurements. SyMRI provided images of sufficient quality in 12/52 (23.08%) (range, 23 + 6-34 + 0) fetal multidynamic multiecho sequence acquisitions. The fetal brain maturity score positively correlated with gestational age at MR imaging (SyMRI: r = 0.915, P < .001/standard of reference: r = 0.966, P < .001). Myelination-related changes in the T2 relaxation time/T2 relaxation rate of the medulla oblongata significantly correlated with gestational age at MR imaging (T2-relaxation time: r = -0.739, P = .006/T2-relaxation rate: r = 0.790, P = .002). Fetal motion limits the applicability of multidynamic multiecho-based postprocessing. However, SyMRI-generated image data of sufficient quality enable the qualitative assessment of maturity-related changes of the fetal brain. In addition, quantitative T2 relaxation time/T2 relaxation rate mapping characterizes myelin-related changes of the brain stem prenatally. This approach, if successful, opens novel possibilities for the evaluation of structural and biochemical aspects of fetal brain maturation.

Neuroimaging Features of Ectopic Cerebellar Tissue: A Case Series Study of a Rare Entity.

Ectopic cerebellar tissue is a rare entity likely secondary to multiple, interacting, developmental errors during embryogenesis. Multiple sites of ectopic cerebellar tissue have been reported, including extracranial locations; however, an intracranial location is most common. We report on the MR imaging findings of a multi-institutional series of 7 ectopic cerebellar tissue cases (2 males, 4 females, 1 fetal) ranging from 22 weeks 5 days' gestational age to 18 years of age. All cases of ectopic cerebellar tissue were diagnosed incidentally, while imaging was performed for other causes. Ectopic cerebellar tissue was infratentorial in 6/7 patients and supratentorial in 1/7 patients. All infratentorial ectopic cerebellar tissue was connected with the brain stem or cerebellum. MR imaging signal intensity was identical to the cerebellar gray and white matter signal intensity on all MR imaging sequences in all cases. Ectopic cerebellar tissue should be considered in the differential diagnoses of extra-axial masses with signal characteristics similar to those of the cerebellum. Surgical biopsy or resection is rarely necessary, and in most cases, MR imaging is diagnostic.

MRI Signal Intensity and Electron Ultrastructure Classification Predict the Long-Term Outcome of Skull Base Chordomas.

MR imaging is a useful and widely used evaluation for chordomas. Prior studies have classified chordomas into cell-dense type and matrix-rich type according to the ultrastructural features. However, the relationship between the MR imaging signal intensity and ultrastructural classification is unknown. We hypothesized that MR imaging signal intensity may predict both tumor ultrastructural classification and prognosis. Seventy-nine patients with skull base chordomas who underwent 95 operations were included in this retrospective single-center series. Preoperative tumor-to-pons MR imaging signal intensity ratios were calculated and designated as ratio on T1 FLAIR sequence (RT1), ratio on T2 sequence (RT2), and ratio on enhanced T1 FLAIR sequence (REN), respectively. We assessed the relationships among signal intensity ratios, ultrastructural classification, and survival. Compared with the matrix-rich type group, the cell-dense type chordomas showed lower RT2 (cell-dense type: 1.90 ± 0.38; matrix-rich type: 2.61 ± 0.60 P < .001). The model of predicting cell-dense type based on RT2 had an area under the curve of 0.83 (95% CI, 0.75-0.92). In patients without radiation therapy, both progression-free survival (P = .003) and overall survival (P = .002) were longer in the matrix-rich type group than in the cell-dense type group. REN was a risk factor for progression-free survival (hazard ratio = 10.24; 95% CI, 1.73-60.79); RT2 was a protective factor for overall survival (hazard ratio = 0.33; 95% CI, 0.12-0.87); and REN was a risk factor for overall survival (hazard ratio = 4.76; 95% CI, 1.51-15.01). The difference in MR imaging signal intensity in chordomas can be explained by electron microscopic features. Both signal intensity ratios and electron microscopic features may be prognostic factors.

PEGylated Bilirubin-coated Iron Oxide Nanoparticles as a Biosensor for Magnetic Relaxation Switching-based ROS Detection in Whole Blood.

Rationale: Magnetic relaxation switching (MRSw) induced by target-triggered aggregation or dissociation of superparamagnetic iron oxide nanoparticles (SPIONs) have been utilized for detection of diverse biomarkers. However, an MRSw-based biosensor for reactive oxygen species (ROS) has never been documented.Methods: To this end, we constructed a biosensor for ROS detection based on PEGylated bilirubin (PEG-BR)-coated SPIONs (PEG-BR@SPIONs) that were prepared by simple sonication via ligand exchange. In addition, near infra-red (NIR) fluorescent dye was loaded onto PEG-BR@SPIONs as a secondary option for fluorescence-based ROS detection.Results: PEG-BR@SPIONs showed high colloidal stability under physiological conditions, but upon exposure to the model ROS, NaOCl, in vitro, they aggregated, causing a decrease in signal intensity in T2-weighted MR images. Furthermore, ROS-responsive PEG-BR@SPIONs were taken up by lipopolysaccharide (LPS)-activated macrophages to a much greater extent than ROS-unresponsive control nanoparticles (PEG-DSPE@SPIONs). In a sepsis-mimetic clinical setting, PEG-BR@SPIONs were able to directly detect the concentrations of ROS in whole blood samples through a clear change in T2 MR signals and a 'turn-on' signal of fluorescence.Conclusions: These findings suggest that PEG-BR@SPIONs have the potential as a new type of dual mode (MRSw-based and fluorescence-based) biosensors for ROS detection and could be used to diagnose many diseases associated with ROS overproduction.

MR imaging features of orbital Langerhans cell Histiocytosis

BackgroundTo investigate the magnetic resonance imaging (MRI) features of orbital Langerhans cell histiocytosis (LCH) to improve diagnostic accuracy.MethodsWe retrospectively reviewed clinical manifestations and MRI findings of 23 patients with histopathology-confirmed LCH of the orbit. The findings were evaluated for the following: (a) symptoms, (b) disease duration, (c) location, (d) configuration, (e) margin, (f) MR imaging signal intensity and enhanced performance.ResultsEighteen patients (78%) in our series were male, only five (22%) patients were female, and the mean age at presentation was 6.3 years. The common symptoms include swollen eyelids, exophthalmos, and a palpable mass. Fourteen patients presented with swollen eyelids and/or exophthalmos. Twenty-two cases involved unilateral orbits, and one case involved bilateral orbits. In our study, there was one patient with cough and expectoration, and one patient with polydipsia and polyuria. Lesions were located in the superior or superlateral orbital roof of seventeen patients (74%). Lesions formed masses or irregular shapes. The 12 out of 23 (52.2%) cases appeared heterogeneous isointense and 10 out of 23 (43.5%) cases showed iso-hypointense on T1-weighted imaging, there were 15 out of 23 (65.2%) cases showed hyper-hypointense mixed signals on T2-weighted imaging. 7 cases found patchy hyperintense signal on T1WI, and 11 cases showed markedly hyperintense signal near the edge of lesions on T2WI. After enhancement, 21 out of 23 (91.3%) cases lesions presented marked enhancement at the edges and the surrounding tissues, and with heterogeneous obvious enhancement of the lesion center. Besides, four cases lesions were surrounded by a low circular signal.ConclusionThere were several characteristics MRI features that can provide crucial information for clinicians and improve our understanding and the diagnostic accuracy of the orbital LCH.

Gd2O3:Pr3+ nanospheres as bi-functional contrast agents for optical and magnetic resonance imaging properties

Gadolinium based luminescent materials have been researched due to their unique optical and magnetic properties with excellent chemical stability, which are useful to apply in both magnetic resonance imaging (MRI) and fluorescence imaging (FI). In this work, red emitting Gd2O3:Pr3+ nanospheres were successfully fabricated by a facile co-precipitation method. The change of reaction time influenced the size of Gd2O3:Pr3+ nanospheres and exhibited the sizes between 110 and 250 nm. The size of the Gd2O3:Pr3+ nanospheres influenced the luminescence and MR imaging signal intensity. Therefore, it can be applied for bi-functional contrast agents.

MRI Findings of Early Myositis Ossificans without Calcification or Ossification.

Purpose To characterize and evaluate the MR imaging features of early myositis ossificans (MO) without calcification or ossification. Methods The MRI manifestations of seven patients with pathologically proven early MO were retrospectively analyzed with regard to tumor location, size, margins, signal intensity, and enhancement appearance in MR images. Additionally, the surrounding soft-tissue edema and adjacent bone change were assessed. Results All cases (n=7) had intramuscular tumor-like masses without calcifications. The lesions appeared as isointense in T1-weighted images (T1-WI) and inhomogeneous hyperintense in T2-weighted MR images (T2-WI). On T2-WI and postcontrast T1-WI, the heterogeneously high signal intensity in the expanded muscle interspersed with a few hypointense linear structures consistent with intact muscle fibers showed “striate pattern” in the plane parallel with muscle fibers. The relatively hypointense areas with geometrical pattern consistent with the bundles of intact muscle fibers are found within the lesion with diffuse high signal intensity, displaying the “checkerboard-like pattern” in the plane vertical to muscle fibers. A “striate pattern” (n = 7) and “checkerboard-like pattern” (n = 3) in the lesion appeared in T2-WI. In contrast-enhanced MRI images, all cases showed diffuse “striate pattern” enhancement. Among them, one case demonstrated “checkerboard-like pattern” enhancement. All cases had diffuse and prominent muscle edema that preserved the muscle fascicles. For two lesions located in the deep muscle group, the adjacent bone showed bone marrow edema. Conclusion MR imaging has unique advantages for diagnosis of early MO without calcification or ossification: the “striate pattern” and “checkerboard-like pattern” appearance shown in T2-WI and contrast-enhanced MRI images can be helpful for differential diagnosis. MRI can delineate the extent of the tumor and provides accurate anatomical information, which is important in diagnosis, treatment, and follow-up.

The relationship between the degree of displacement of the atlas to axis and the clinical data in atlanto-axial subluxation due to rheumatoid arthritis.

The most common type of anatomical cervical spine involvement is atlanto-axial subluxation (AAS) in rheumatoid arthritis (RA). The purpose of this study was to clarify the relationship between the displacement of the atlas to axis and the clinical data obtained in patients with AAS due to RA. Fifty patients with AAS due to RA that were treated by surgery are herein reviewed. Based on the findings of preoperative lateral cervical radiographs in the neutral position, the patients were classified into two groups as follows: a 10 + group with an atlanto-dental interval (ADI) of ≧ 10mm, and a 10 - group with an ADI < 10mm. Preoperative lateral cervical radiographs demonstrated 15 cases to belong to the 10 + group, while 35 cases belonged to the 10 - group. In the preoperative MR imaging, an intramedullary high signal intensity was observed in seven cases that belonged to the 10 + group and in four cases belonging to the 10 - group. Regarding the neurological severity, the 10 + group included significantly more cases showing severe neurological deficits before surgery; however, there was no significant difference between the two groups regarding the presence of severe deficits even after surgery. The severe displacement group included significantly more cases showing an intramedullary high signal intensity in the preoperative MR images. Our results also suggest that a severe displacement before surgery affected the presence of neurological deficits before surgery; however, it did not affect the neurological recovery from such severe neurological deficits.

Migration of Bone Wax into the Sigmoid Sinus after Posterior Fossa Surgery

Bone wax is a hemostatic agent that has been reported in some instances to migrate into the sigmoid sinus following posterior fossa surgery. The purpose of this study was to characterize the CT and MR imaging findings of this entity. The study included 212 consecutive patients who underwent posterior fossa surgery and postoperative CT and contrast-enhanced MR imaging. The presence of sigmoid sinus bone wax migration was determined with the following criteria: sigmoid sinus filling defect showing low signal on all MR imaging pulse sequences; sigmoid sinus filling defect showing low CT attenuation, similar to fat attenuation; and clinical confirmation that bone wax was used intraoperatively. CT and MR imaging of an in vitro bone wax sample was also performed. We identified 6 cases of sigmoid sinus bone wax migration. In each case, a low-signal-intensity, low-attenuation filling defect was noted in the sigmoid sinus. The morphology was linear (n = 3) or globular (n = 3). In patients with serial imaging, the appearance of migrated bone wax remained stable over time. No adverse outcomes related to sigmoid sinus bone wax migration were encountered. In vitro imaging of bone wax confirmed low CT attenuation and low MR imaging signal intensity on T1WI and T2WI. Bone wax migration into the sigmoid sinus is a recognizable imaging finding after posterior fossa surgery that appears to have a benign clinical course. The finding should be distinguished from more serious complications, such as venous sinus thrombosis.

Analysis of T2 signal intensity helps in the differentiation between high and low-grade brain tumours in paediatric patients

Previous studies hypothesized that the analysis of magnetic resonance intensity of the solid portion in paediatric tumours can provide pre-surgical information about the histopathology. Classically, high signal-intensity in T2weighted (T2w) images identifies low-grade tumours, while anaplasia is characterized by T2 hypointensity. We aimed to investigate if T2w signal intensities can pre-operatively distinguish between low-grade and high-grade brain tumours in paediatric patients. Two raters, blinded to the histological diagnosis, rated the signal intensity of MR images (T2w) from 36 children with newly diagnosed brain tumours, 17 children with low-grade brain tumours and 19 children with high-grade brain tumours were included in this study. Relative T2 values were obtained by dividing the T2w values of the solid portion of the tumour by the T2w values of the vitreous humour. The best cut-off point to distinguish low and high-grade paediatric brain tumours was 0.8. If the signal intensity was less than or equal to 0.8 the tumour was expected to be a high-grade tumour with a sensitivity of 100%. Prediction of a low-grade tumour was more uncertain with a sensitivity of 70.5%. Overall, 86% of the tumours would have been predicted correctly. Our data suggest that T2w signal intensities of the solid portion of brain tumours in paediatrics can pre-operatively differentiate between low-grade and high-grade tumours. In addition, T2 hypointensity may be helpful in targeting stereotactic biopsy.

Quantifying perfusion-related energy losses during magnetic resonance-guided focused ultrasound

The focused ultrasound power required for successful ablation of uterine fibroid tissue varies substantially between patients and within single treatments.[1,2] Fibroids with high signal intensity in pretreatment T2-weighted MR images have been shown to require increased power to achieve adequate temperature elevation for ablation;[2,4] thus, T2-weighted signal intensity has been suggested as a predictor of MRgFUS treatment response.[2,3] Physiologically, the high intensity of T2-weighted MR images of uterine fibroids may represent vascularization, fluid-rich tissues, or degeneration.[4,6] By quantifying perfusion-related energy losses (Qb) during MRgFUS treatments, this study is the first step in linking perfusion-related energy losses with MR perfusion imaging. This knowledge could be used to improve biothermal modeling of MRgFUS fibroid treatments and as a potential independent predictor of treatment response and outcome.

MRI predictors of clinical success in MR-guided focused ultrasound (MRgFUS) treatments of uterine fibroids: results from a single centre.

To assess the technical and clinical results of MRgFUS treatment and factors affecting clinical treatment success. A total of 252 women (mean age, 42.1 ± 6.9 years) with uterine fibroids underwent MRgFUS. All patients underwent MRI before treatment. Results were evaluated with respect to post-treatment nonperfused volume (NPV), symptom severity score (SSS), reintervention rate, pregnancy and safety data. NPV ratio was significantly higher in fibroids characterized by low signal intensity in contrast-enhanced T1-weighted fat saturated MR images and in fibroids distant from the spine (>3 cm). NPV ratio was lower in fibroids with septations, with subserosal component and in skin-distant fibroids (p < 0.001). NPV ratio was highly correlated with clinical success: NPV of more than 80 % resulted in clinical success in more than 80 % of patients. Reintervention rate was 12.7 % (mean follow-up time, 19.4 ± 8 months; range, 3-38). Expulsion of fibroids (21 %) was significantly correlated with a high clinical success rate. No severe adverse events were reported. Adequate patient selection and correct treatment techniques, based on the learning curve of this technology, combined with technical advances of the system, lead to higher clinical success rates with low complications rate, comparable to other uterine-sparing treatment options. • MRgFUS appears to be a valid alternative to other uterus-preserving therapies • Patient selection is a significant factor in achieving high NPV ratios • MRI screening parameters correlate with the amount of fibroid ablation in MRgFUS • NPV results of more than 80 % correlate with higher clinical success rates.

Conventional magnetic resonance imaging in the differentiation between high and low-grade brain tumours in paediatric patients

ObjectiveIt has been described that hyperintensity in diffusion-weighted imaging (DWI) correlates with high-grade tumours, and high signal-intensity in T2-weighted (T2w) images identifies low-grade tumours. We aimed to investigate the potential of routine conventional MRI sequences, such as DWI and T2-w, to pre-operatively distinguish between low-grade and high-grade brain tumours in paediatric patients. Material and methodsTwo raters, blinded to the histological diagnosis, rated the aspect and signal intensity of MR images (T2w and DWI) from 37 children with newly diagnosed brain tumours. Histological diagnoses included 18 low-grade and 19 high-grade brain tumours. ResultsThe inter-rater agreement was 81–95%. High-grade tumours were never hypointense on DWI and low-grade tumours were usually hyperintense on T2w. Specificity was 100% for low-grade tumours and 90% for high-grade tumours. About 95% of the high-grade tumours and about 70% of the low-grade tumours were correctly diagnosed. ConclusionThe combination of general morphological aspect of the tumours and signals on T2-w and DWI yield a high accuracy of pre-operative differentiation between low-grade and high-grade paediatric tumours.

Gold-Coated Iron Oxide Nanoparticles as a T2 Contrast Agent in Magnetic Resonance Imaging

Gold-coated iron oxide (Fe3O4) nanoparticles were synthesized for use as a T2 contrast agent in magnetic resonance imaging (MRI). The coated nanoparticles were spherical in shape with an average diameter of 20 nm. The gold shell was about 2 nm thick. The bonding status of the gold on the nanoparticle surfaces was checked using a Fourier transform infrared spectrometer (FTIR). The FTIR spectra confirmed the attachment of homocysteine, in the form of thiolates, to the Au shell of the Au-Fe3O4 nanoparticles. The relaxivity ratio, R2/R1, for the coated nanoparticles was 3-fold higher than that of a commercial contrast agent, Resovist, which showed the potential for their use as a T2 contrast agent with high efficacy. In animal experiments, the presence of the nanoparticles in rat liver resulted in a 71% decrease in signal intensity in T2-weighted MR images, indicating that our gold-coated iron oxide nanoparticles are suitable for use as a T2 contrast agent in MRI.

A Distinct MR Imaging Phenotype in Amyotrophic Lateral Sclerosis: Correlation between T1 Magnetization Transfer Contrast Hyperintensity along the Corticospinal Tract and Diffusion Tensor Imaging Analysis

In the search for a diagnostic marker in ALS, we focused our attention on the hyperintense signal intensity in T1 MTC MR images along the CST, detected in some patients and not found in other patients with ALS and in control subjects. The aim of this study was to investigate the relationship between the hyperintense signal intensity in T1 MTC images and white matter damage. To this purpose, we studied potential heterogeneities in DTI values within our patients by using TBSS without a priori anatomic information. In 43 patients with ALS and 43 healthy control subjects, the presence or absence of T1 MTC hyperintense signal intensity was evaluated. With a DTI analysis with a TBSS approach, differences in FA distribution between the 2 groups (patients with T1 MTC hyperintense signal intensity and patients without it) compared with each other and with control subjects were investigated. We found regional differences in white matter FA between patients with T1 MTC hyperintense signal intensity (37.2%) and patients without it. Patients with T1 MTC abnormal signal intensity showed lower FA strictly limited to the motor network and the posterior aspect of the body of the CC without extramotor FA reductions, whereas patients without this sign showed FA reductions in several confluent regions within and outside the CST and in the whole CC. T1 MTC hyperintense signal intensity in the CST and posterior CC, when present, is specific for ALS and represents, among patients with ALS, a possible distinct phenotype of presentation of the disease with prominent UMN involvement.

Nasal Cavity Eosinophilic Angiocentric Fibrosis: CT and MR Imaging Findings

EAF consists of exceedingly rare lesions and presently lacks specific imaging reports. The purpose of this study was to determine the CT and MR imaging features of nasal cavity EAF. We retrospectively reviewed 6 patients with histology-proven EAF in the nasal cavity. All 6 patients underwent CT and 3 patients also underwent MR imaging. The following imaging features were reviewed: 1) location, 2) shape, 3) margin, 4) CT attenuation, and 5) MR imaging signal intensity. In addition, the accompanying changes and the TIC of the DCE MR imaging were analyzed. All occurrences of EAF were located at the anterior nasal cavity, arising from the nasal septum in 4 patients, with irregular shape, and the lateral nasal wall in 2, with oval configuration. The mean size was 29.8 mm (range 12-52 mm). On nonenhanced CT, EAF lesions appeared isoattenuated relative to gray matter. On the T1-weighted image, the lesions were isointense in 3 (100%) patients. On the T2-weighted image, the lesions were isointense in 1 (33.3%) patient and hypointense in 2 (66.7%) patients. Occurrences of EAF revealed moderate inhomogeneous contrast enhancement. Three patients underwent DCE MR imaging and the TICs exhibited a rapidly enhancing and slow washout pattern. One patient had bilateral lacrimal gland enlargement, which displayed low signal intensity on the T2-weighted image. A familiarity with imaging findings, including lesion location, isoattenuation and bony changes, and hypointensity on T2-weighted images may help to accurately diagnose this rare entity.

Imaging-Pathologic Correlation in Corticobasal Degeneration

The clinical diagnosis of corticobasal degeneration (CBD) is often difficult due to varied clinical manifestations. In 4 patients with neuropathologically confirmed CBD, characteristic imaging findings and correlations with neuropathologic features were evaluated. Furthermore, imaging findings in CBD were compared with neuropathologically confirmed progressive supranuclear palsy (PSP) for a differential diagnosis. Four patients with neuropathologically confirmed CBD were studied. We evaluated the area of the tegmentum in the midsagittal plane, subcortical white matter (SCWM) abnormality, asymmetric cerebral atrophy, and signal-intensity abnormality in the subthalamic nuclei on MR imaging and compared them with histopathologic findings. Then, MR imaging findings in CBD were compared with those in 13 patients with PSP. On MR imaging, 3 patients had asymmetric cerebral atrophy extending to the central sulcus. On midsagittal sections, the mean midbrain tegmentum area was 66 mm(2), being markedly smaller than normal, but there was no significant difference between PSP and CBD. All patients had signal-intensity abnormalities of the SCWM, constituting primary degeneration neuropathologically; however, no diffuse signal-intensity abnormality in the SCWM existed in the 13 patients with PSP. In 3 patients, T1-weighted images showed symmetric high signal intensity in the subthalamic nuclei. Neuropathologically, these areas showed characteristic CBD. MR imaging signal-intensity changes also existed in 4 patients with PSP; however, subthalamic nucleus degeneration was more severe in PSP than in CBD. In cases with midbrain tegmentum atrophy and signal-intensity changes in the subthalamic nuclei, the differential diagnosis distinguishing CBD from PSP based on MR imaging alone was difficult. White matter lesions and asymmetric atrophy can be useful for a differential diagnosis.

Isolated Reversible Thalamic Vasogenic Edema Following a Generalized Seizure: Fig 1.

Transient MR imaging signal-intensity changes in the thalamus, usually accompanied by signal-intensity changes elsewhere in the brain, have been previously reported in the setting of seizures.[1][1]–[3][2] We report a case in which an MR image obtained shortly after a seizure episode demonstrated