Faster acquisition of magnetic resonance imaging sequences of the knee via deep learning reconstruction: a volunteer study.

AIM: To evaluate whether deep learning reconstruction (DLR) can accelerate the acquisition of magnetic resonance imaging (MRI) sequences of the knee for clinical use. MATERIALS AND METHODS: Using a 1.5-T MRI scanner, sagittal fat-suppressed T2-weighted imaging (fs-T2WI), coronal proton density-weighted imaging (PDWI), and coronal T1-weighted imaging (T1WI) were performed. DLR was applied to images with a number of signal averages (NSA) of 1 to obtain 1DLR images. Then 1NSA, 1DLR, and 4NSA images were compared subjectively, and by noise (standard deviation of intra-articular water or medial meniscus) and contrast-to-noise ratio between two anatomical structures or between an anatomical structure and intra-articular water. RESULTS: Twenty-seven healthy volunteers (age: 40.6 ± 11.9 years) were enrolled. Three 1DLR image sequences were obtained within 200 s (approximately 12 minutes for 4NSA image). According to objective evaluations, PDWI 1DLR images showed the smallest noise and significantly higher contrast than 1NSA and 4NSA images. For fs-T2WI, smaller noise and higher contrast were observed in the order of 4NSA, 1DLR, and 1NSA images. According to the subjective analysis, structure visibility, image noise, and overall image quality were significantly better for PDWI 1DLR than 1NSA images; moreover, the visibility of the meniscus and bone, image noise, and overall image quality were significantly better for 1DLR than 4NSA images. Fs-T2WI and T1WI 1DLR images showed no difference between 1DLR and 4NSA images. CONCLUSION: Compared to PDWI 4NSA images, PDWI 1DLR images were of higher quality, while the quality of fs-T2WI and T1WI 1DLR images was similar to that of 4NSA images.

Usefulness of deep learning-based noise reduction for 1.5 T MRI brain images.

AIM: To evaluate 1.5 T magnetic resonance imaging (MRI) brain images with denoising procedures using deep learning-based reconstruction (dDLR) relative to the original 1.5 and 3 T images. MATERIALS AND METHODS: Eleven volunteers underwent MRI at 3 and 1.5 T. Two-dimensional fast spin-echo T2-weighted imaging (T2WI), fluid-attenuated inversion recovery (FLAIR) imaging and diffusion-weighted imaging (DWI) sequences were performed. The dDLR method was applied to the 1.5 T data (dDLR-1.5 T), then the image quality of the dDLR-1.5 T data relative to the original 1.5 T and 3 T data was qualitatively and quantitatively assessed based on the structure similarity (SSIM) index; the signal-to-noise ratios (SNRs) of the grey matter (GM) and white matter (WM); and the contrast-to-noise ratios (CNRs) between the GM and WM (CNRgm-wm) and between the striatum (ST) and WM (CNRst-wm). RESULTS: The perceived image quality, and SNRs and CNRs were significantly higher for the dDLR-1.5 T images versus the 1.5 T images for all sequences and almost comparable or even superior to those of the 3 T images. For DWI, the SNRs and CNRst-wm were significantly higher for the dDLR-1.5 T images versus the 3 T images. CONCLUSION: The dDLR technique improved the image quality of 1.5 T brain MRI images. With respect to qualitative and quantitative measurements, the denoised 1.5 T brain images were almost equivalent or even superior to the 3 T brain images.

Predicting prognosis of resected hepatocellular carcinoma by radiomics analysis with random survival forest.

RATIONALE AND OBJECTIVES: To investigate the impact of random survival forest (RSF) classifier trained by radiomics features over the prediction of the overall survival of patients with resectable hepatocellular carcinoma (HCC). MATERIALS AND METHODS: The dynamic computed tomography data of 127 patients (97 men, 30 women; mean age, 68 years) newly diagnosed with resectable HCC were retrospectively analyzed. After manually setting the region of interest to include the tumor within the slice at its maximum diameter, texture analyses were performed with or without a Laplacian of Gaussian filter. Using the extracted 96 histogram based texture features, RSFs were trained using 5-fold cross-validation to predict the individual risk for each patient on disease free survival (DFS) and overall survival (OS). The associations between individual risk and DFS or OS were evaluated using Kaplan-Meier analysis. The effects of the predicted individual risk and clinical variables upon OS were analyzed using a multivariate Cox proportional hazards model. RESULTS: Among the 96 histogram based texture features, RSF extracted 8 of high importance for DFS and 15 for OS. The RSF trained by these features distinguished two patient groups with high and low predicted individual risk (P=1.1×10-4 for DFS, 4.8×10-7 for OS). Based on the multivariate Cox proportional hazards model, high predicted individual risk (hazard ratio=1.06 per 1% increase, P=8.4×10-8) and vascular invasion (hazard ratio=1.74, P=0.039) were the only unfavorable prognostic factors. CONCLUSIONS: The combination of radiomics analysis and RSF might be useful in predicting the prognosis of patients with resectable HCC.

The relationship of waist circumference and body mass index to grey matter volume in community dwelling adults with mild obesity.

Objective: Previous work has shown that high body mass index (BMI) is associated with low grey matter volume. However, evidence on the relationship between waist circumference (WC) and brain volume is relatively scarce. Moreover, the influence of mild obesity (as indexed by WC and BMI) on brain volume remains unclear. This study explored the relationships between WC and BMI and grey matter volume in a large sample of Japanese adults. Methods: The participants were 792 community-dwelling adults (523 men and 269 women). Brain magnetic resonance images were collected, and the correlation between WC or BMI and global grey matter volume were analysed. The relationships between WC or BMI and regional grey matter volume were also investigated using voxel-based morphometry. Results: Global grey matter volume was not correlated with WC or BMI. Voxel-based morphometry analysis revealed significant negative correlations between both WC and BMI and regional grey matter volume. The areas correlated with each index were more widespread in men than in women. In women, the total area of the regions significantly correlated with WC was slightly greater than that of the regions significantly correlated with BMI. Conclusions: Results show that both WC and BMI were inversely related to regional grey matter volume, even in Japanese adults with somewhat mild obesity. Especially in populations with less obesity, such as the female participants in current study, WC may be more sensitive than BMI as a marker of grey matter volume differences associated with obesity.

Computer-Assisted Detection of Cerebral Aneurysms in MR Angiography in a Routine Image-Reading Environment: Effects on Diagnosis by Radiologists.

BACKGROUND AND PURPOSE: Experiences with computer-assisted detection of cerebral aneurysms in diagnosis by radiologists in real-life clinical environments have not been reported. The purpose of this study was to evaluate the usefulness of computer-assisted detection in a routine reading environment. MATERIALS AND METHODS: During 39 months in a routine clinical practice environment, 2701 MR angiograms were each read by 2 radiologists by using a computer-assisted detection system. Initial interpretation was independently made without using the detection system, followed by a possible alteration of diagnosis after referring to the lesion candidate output from the system. We used the final consensus of the 2 radiologists as the reference standard. The sensitivity and specificity of radiologists before and after seeing the lesion candidates were evaluated by aneurysm- and patient-based analyses. RESULTS: The use of the computer-assisted detection system increased the number of detected aneurysms by 9.3% (from 258 to 282). Aneurysm-based analysis revealed that the apparent sensitivity of the radiologists' diagnoses made without and with the detection system was 64% and 69%, respectively. The detection system presented 82% of the aneurysms. The detection system more frequently benefited radiologists than being detrimental. CONCLUSIONS: Routine integration of computer-assisted detection with MR angiography for cerebral aneurysms is feasible, and radiologists can detect a number of additional cerebral aneurysms by using the detection system without a substantial decrease in their specificity. The low confidence of radiologists in the system may limit its usefulness.

Brain diffusivity pattern is individual-specific information.

The human brain is composed of complex networks of 100 billion neurons that underlie its higher functions. The set of neural connections in the brain has recently attracted growing interest from the scientific community. It is important to identify individual differences in these neural connections to study the background of individual differences in brain function and performance. In the present study, we investigated whether the pattern of brain diffusion, reflecting neural connections, is discernibly different among individuals; i.e., whether brain diffusivity is personally identifiable information. Using diffusion tensor imaging data from 224 healthy subjects scanned twice at an interval of about 1year, we performed brain recognition by spatial normalization of fractional anisotropy maps, feature extraction based on Principal Component Analysis, and calculation of the Euclidean distances between image pairs projected into the subspace. Even with only 16 dimensions used for projection, the rank-one identification rate was 99.1%. The rank-one identification rate was 100% with ⩾32 dimensions used for projection. The genuine accept rates were 95.1% and 100% at a false accept rate of 0.001%, with 16 and ⩾32 dimensions used for projection, respectively. There were no large differences in the Euclidean distance among different combinations of scanners used or between image pairs with and without scanner upgrade. The results indicate that brain diffusivity can identify a specific individual; i.e., the pattern of brain diffusion is personally identifiable information. Individual differences in brain diffusivity will form the basis of individual differences in personality and brain function.

Influence of parameter settings in voxel-based morphometry 8. Using DARTEL and region-of-interest on reproducibility in gray matter volumetry.

OBJECTIVES: To investigate whether reproducibility of gray matter volumetry is influenced by parameter settings for VBM 8 using Diffeomorphic Anatomical Registration Through Exponentiated Lie Algebra (DARTEL) with region-of-interest (ROI) analyses. METHODS: We prepared three-dimensional T1-weighted magnetic resonance images (3D-T1WIs) of 21 healthy subjects. All subjects were imaged with each of five MRI systems. Voxel-based morphometry 8 (VBM 8) and WFU PickAtlas software were used for gray matter volumetry. The bilateral ROI labels used were those provided as default settings with the software: Frontal Lobe, Hippocampus, Occipital Lobe, Orbital Gyrus, Parietal Lobe, Putamen, and Temporal Lobe. All 3D-T1WIs were segmented to gray matter with six parameters of VBM 8, with each parameter having between three and eight selectable levels. Reproducibility was evaluated as the standard deviation (mm³) of measured values for the five MRI systems. RESULTS: Reproducibility was influenced by 'Bias regularization (BiasR)', 'Bias FWHM', and 'De-noising filter' settings, but not by 'MRF weighting', 'Sampling distance', or 'Warping regularization' settings. Reproducibility in BiasR was influenced by ROI. Superior reproducibility was observed in Frontal Lobe with the BiasR1 setting, and in Hippocampus, Parietal Lobe, and Putamen with the BiasR3*, BiasR1, and BiasR5 settings, respectively. CONCLUSION: Reproducibility of gray matter volumetry was influenced by parameter settings in VBM 8 using DARTEL and ROI. In multi-center studies, the use of appropriate settings in VBM 8 with DARTEL results in reduced scanner effect.

Polypoidal choroidal vasculopathy and history of central serous chorioretinopathy.

PURPOSE: To evaluate the possible causative role of central serous chorioretinopathy (CSC) in the development of exudative age-related macular degeneration (AMD). METHODS: In a cross-sectional study at an institutional setting, 150 control subjects who had senile cataract or nasolacrimal duct stenosis and who were older than 50 years were enrolled. The background data for 89 patients with typical AMD (tAMD) and 138 patients with polypoidal choroidal vasculopathy (PCV) were used for comparison. Their medical records were taken for history of CSC, hypertension, systemic steroid use, and smoking. The fundus was also evaluated for signs of atrophic retinal pigment epithelial (RPE) tract and for focal photocoagulation scars in the macula. RESULTS: After adjusting for age, gender, and history of hypertension, systemic steroid use, and smoking, history of CSC was significantly more frequent (P<0.0001) in patients with PCV (15 patients, 10.9%) compared with patients with tAMD (2 patients, 2.2%) or control subjects (0 patients). On fundoscopy, an atrophic RPE tract (seven patients) or a focal photocoagulation scar (one patient) was observed only in patients with PCV (eight patients, 5.8%), and the frequency was statistically significant compared with that with tAMD (P=0.0143) or control subjects (P=0.0143). The laterality of CSC and AMD involved the same eye in 9 of 10 patients among those who had unilateral AMD and a reported unilateral CSC history. CONCLUSION: A history of CSC may be a predisposing factor for the development of PCV in the Japanese population.

Late enhancement of brain-behavior correlations during response inhibition.

Previous neuroimaging studies of response inhibition have examined correlations between behavioral efficiency and brain activity, but the temporal stability of the correlations has largely been ignored. The present functional magnetic resonance imaging (fMRI) study demonstrates the temporal changes of the brain activity associated with performance efficiency that led to more robust brain-behavior correlations in a later part of the experimental sessions. Participants performed a stop-signal task requiring inhibition of inappropriate responses, where more efficient behavioral performance is reflected in a shorter stop-signal reaction time (SSRT). Among across-subject negative correlations between the brain activity and the SSRT, the majority of the negative correlations were observed in the second half of experimental sessions. In the cerebellar region that showed the greatest difference in correlations between the second and the first halves, the brain activity increased in efficient performers, whereas the brain activity decreased in poor performers. These results suggest the existence of multiple brain mechanisms that increase and decrease the brain activity depending on the behavioral efficiency of the performers. More practically, these results indicate that robust brain-behavior correlations can more effectively be detected in a later part of the experimental sessions.

Salvage radiation therapy and chemoradiation therapy for postoperative locoregional recurrence of esophageal cancer.

The purpose of this retrospective study was to assess the efficacy of salvage radiation therapy (RT) or chemoradiation therapy (CRT) for locoregional recurrence (LR) of esophageal cancer after curative surgery. Forty-two patients who received salvage RT or CRT for LR of esophageal cancer after curative surgery between November 2000 and May 2012 were reviewed. The intended RT regimen was 60 Gy in 30 fractions combined with concurrent platinum-based chemotherapy. Median follow-up periods were 17.9 months for all evaluable patients and 28.2 months for patients still alive (19 patients) at analysis time. The 1-, 2-, and 3-year survival rates were 81.2 ± 6.4%, 51.3 ± 8.6%, and 41.1 ± 8.7%, respectively, with a median survival time of 24.3 ± 4.1 months. Out of 41 evaluable patients, 16 patients (39%) were alive beyond 2 years from salvage therapy. However, univariate analyses for overall survival showed no significant prognostic factor. Grade 3 or higher leukocytopenia was observed in 46% of the patients. Salvage RT or CRT for LR after surgery for esophageal cancer was safe and effective. These therapies may offer long-term survival to some patients. RT or CRT should be considered for LR.

Postoperative transient reduced diffusion in the ipsilateral striatum and thalamus.

BACKGROUND AND PURPOSE: Restriction of diffusion has been reported in the early phase of secondary neuronal degeneration, such as wallerian degeneration. The purpose of this study was to investigate postoperative transient reduced diffusion in the ipsilateral striatum and thalamus as a remote effect of surgery. MATERIALS AND METHODS: Six hundred two postoperative MR imaging examinations in 125 patients after cerebral surgery were retrospectively reviewed, focusing on the presence of reduced diffusion in the striatum and/or thalamus. The distribution of reduced diffusion in the striatum was classified into 3 groups: anterior, central, and posterior. Reduced diffusion in the thalamus was also classified on the basis of the anatomic locations of the thalamic nuclei. Further follow-up MRI was available in all patients with postoperative reduced diffusion, and acute infarctions were excluded. The patient medical records were reviewed to evaluate neurologic status. RESULTS: Restriction of diffusion was observed in the striatum and/or thalamus ipsilateral to the surgical site in 17 patients (13.6%). The distribution of signal abnormality correlated with the location of the operation, in concordance with the architecture of the striatocortical and thalamocortical connections. Reduced diffusion was observed from days 7 to 46 after the operation, especially during days 8-21. The signal abnormalities completely resolved on follow-up examinations. The median follow-up period was 202 days (interquartile range, 76-487 days). CONCLUSIONS: Postoperative transient reduced diffusion in the ipsilateral striatum and/or thalamus likely represents an early phase of secondary neuronal degeneration based on its characteristic distribution and time course. Clinically, this reduced diffusion should not be mistaken for postoperative ischemic injury.

White matter microstructure asymmetry: effects of volume asymmetry on fractional anisotropy asymmetry.

Diffusion tensor imaging (DTI) provides information regarding white matter microstructure; however, macroscopic fiber architectures can affect DTI measures. A larger brain (fiber tract) has a 'relatively' smaller voxel size, and the voxels are less likely to contain more than one fiber orientation and more likely to have higher fractional anisotropy (FA). Previous DTI studies report left-to-right differences in the white matter; however, these may reflect true microscopic differences or be caused purely by volume differences. Using tract-based spatial statistics, we investigated left-to-right differences in white matter microstructure across the whole brain. Voxel-wise analysis revealed a large number of white matter volume asymmetries, including leftward asymmetry of the arcuate fasciculus and cingulum. In many white matter regions, FA asymmetry was positively correlated with volume asymmetry. Voxel-wise analysis with adjustment for volume asymmetry revealed many white matter FA asymmetries, including leftward asymmetry of the arcuate fasciculus and cingulum. The voxel-wise analysis showed a reduced number of regions with significant FA asymmetry compared with analysis performed without adjustment for volume asymmetry; however, the overall trend of the results was unchanged. The results of the present study suggest that these FA asymmetries are not caused by volume differences and reflect microscopic differences in the white matter.

SU-E-J-33: Geometric Agreement Check for Imaging System with Radiation Beam by KV and MV-CBCT.

PURPOSE: The verification method of the geometry agreement between a light field and/or a laser coordinate and treatment beam should be easy and quick. In this presentation, we propose a novel QA method by using both kV- and MV-CBCT for kV-IGRT system. This method confirms the temporal unchanging the agreement of geometry in the kV-IGRT system with the treatment beam geometry. METHODS: 1) MV-flexmap: Sequential MV-projection images were acquired during gantry rotation by iViewGT (Elekta) and MV-CBCT was reconstructed by in-house software with a flexmap correction. The flexmap is displacement of gantry and detector panel related with gantry sag. The geometric change affects the deranging reconstructed image. To evaluate how much displacement of EPID panel and gantry was detectable, the images of 8mm diameter ball-bearing (BB) located at the radiation isocenter were reconstructed with improper Flexmap.2) A comparison between the kV-CBCT and the MV-CBCT: The kV-CBCT was provided by X-ray Volume image (XVI) system (Elekta). To confirm the agreement for the geometry between kV-IGRT system and treatment beam, the kV-CBCTs of BB are compared with that of MV-CBCTs. RESULTS: The flexmaps were modified to (b)1mm / (c)3mm shifted to the rotation direction and (d)3mm to the rotation axis. The MV-CBCT were reconstructed with the correct flexmap and with incorrect flexmap (b), (c) and (d).　The geometric confirmation for MV-CBCT was done by comparison of the width and center of the BB on the MV-CBCT. The discrepancy of center between kV-CBCT and MV-CBCT was less than 1mm. CONCLUSIONS: Less than 1mm of the geometrical changing to rotation direction for MV-detector panel could be recognized by reconstructed images of BB. Using kV- and MV-CBCT enable us to perform the simple comparison for geometrical non-idealities between the kV-IGRT system and the treatment beam. Dr. K. Nakagawa received research grant from Elekta.

SU-E-J-203: Determination of PTV Margin for Lung Tumor Using In-Treatment 4D CBCT.

PURPOSE: To determine a planning target volume (PTV) margin for lung cancer patients using a four-dimensional cone-beam CT (4D CBCT) acquired during volumetric modulated arc therapy (VMAT) treatment. METHODS: A VMAT plan for lung cancer patients was created by Pinnacle v9.0 (Philips) treatment planning system (TPS), where the gross target volume (GTVs) in each breathing phase was delineated by using 4D-planning CT scan (TOSHIBA and ANZAI). The VMAT treatment was performed with a stereotactic body frame after the registration using Elekta X-ray volume imaging (XVI) unit. Simultaneous cone-beam projection images were acquired for 3 or 4 fractions of 10 patients. The in-treatment 4D CBCT was reconstructed by dividing into four breathing phase bins. A total of 38 in-treatment 4D-CBCT sets were exported to Pinnacle TPS. The isocenter of in-treatment 4D CBCT was matched with that of 4D-planning CT. The tumor motion during treatment was manually tracked on in-treatment 4D CBCT, and the center-of-mass (COM) location of the tumor was estimated. Analyzing the tumor regions observed by in-treatment 4D CBCT, a PTV margin in our system was derived. RESULTS: The average difference in COM location of the tumor was less than 1mm for all directions, while the standard deviations (SD's) were about 1.3mm, 1.6mm, and 2.1mm for the lateral, the vertical, and the longitudinal directions, respectively. The large discrepancy more than 3mm was observed for one patient. The required PTV margin was about 3-4mm for the lateral and the vertical directions, whereas it was about 5mm for the longitudinal direction. CONCLUSIONS: The uncertainties of the tumor motion caused by respiration were observed by in-treatment 4D CBCT images. It was feasible to determine the PTV margin from 4D volume images. K. Nakagawa receives research funding from Elekta.

Diagnostic Ability of Fluid-Attenuated Inversion Recovery MR Imaging to Detect Remnant or Recurrent Meningiomas after Resection.

It has been suggested that a difference in signal intensity (SI) between the resection cavity and normal cerebrospinal fluid (CSF) on fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI) in partially resected gliomas indicates subsequent or coincident tumor progression. We considered that this would hold true for resected meningiomas as well. Hence, we aimed to assess whether or not such a difference in the SI during the follow-up evaluation helps predict residual or recurrent tumor in resected meningiomas. We evaluated 63 patients with resected meningiomas. The SI within the resection cavity observed on FLAIR images was qualitatively and quantitatively assessed during follow-up. Qualitative analysis comprised visual comparison of the SI in the resection cavity with that of normal CSF by neuroradiologists. The SI in the resection cavity was quantitatively assessed by region of interest (ROI) analysis and normalized against the background noise and CSF SI. Normalized SI recorded during follow-up was compared with that recorded immediately after resection. Tumor progression was defined as a 20% or greater increase in the diameter of the longest residual or recurrent meningioma (Response Evaluation Criteria in Solid Tumors). The sensitivity and specificity of the elevated SI in the resection cavity for indicating residual or recurrent tumor were calculated. Qualitative analysis by FLAIR MRI showed that patients with remnant tumor following surgery had a prolonged SI increase in the resection cavity. Further, SI increase could not always be observed before recurrence, and both SI increase and regrowth remnant/recurrence could be detected in the same MRI examination. In resected meningiomas, leakage of tumor elements into the resection cavity, presumably tumor cells, manifests as an SI increase on FLAIR images and indicates residual or recurrent tumor. However, unlike the previous reports on partially resected gliomas, we concluded that the SI change does not always precede tumor progression or recurrence.

Effects of age and gender on white matter integrity.

BACKGROUND AND PURPOSE: DTI provides a sensitive measure of change in the microstructure of white matter integrity. The purpose of our study was to investigate age-related changes, sex differences, and age-by-sex interactions in white matter integrity (FA, AD, and RD) across the whole brain with a large sample. MATERIALS AND METHODS: A total of 857 healthy subjects (mean age = 56.1 ± 9.9 years; age range = 24.9-84.8 years) were included in this study. All subjects were scanned at 3T. With use of TBSS, we examined the effects of age and sex on FA, AD, and RD in the white matter. RESULTS: Global FA was negatively correlated with age (R(2) = 0.18, P < .0001), and global AD and RD were positively correlated with age (AD: R(2) = 0.02, P < .0001; RD: R(2) = 0.19, P < .0001). The correlation between age and global AD, however, was weak. Voxelwise analysis revealed a number of regions where FA was negatively correlated with age, with most of these regions showing a significant positive correlation between RD and age. There was a significant age-related FA increase in several white matter regions. Voxelwise analysis also revealed many regions where FA, AD, or RD differed between men and women; however, no region showed a significant interaction between age and sex. CONCLUSIONS: Our results suggest that age-related changes in white matter integrity are more strongly associated with myelin sheath degeneration than with axonal degeneration, and that, in some specific regions, the number of remyelinated axons might increase with age. Our results also suggest that there are no sex differences in the aging process of the white matter.

White matter asymmetry in healthy individuals: a diffusion tensor imaging study using tract-based spatial statistics.

The purpose of this study was to investigate white matter asymmetry across the whole brain and evaluate the effects of age and sex on white matter asymmetry in a large sample of healthy adults. A total of 857 normal subjects (310 females and 547 males, mean age=56.1±9.9 years, age range=24.9-84.8 years) were included in this study. With use of tract-based spatial statistics (TBSS), we investigated white matter fractional anisotropy (FA) asymmetry and evaluated the effects of age and sex on white matter FA asymmetry. The voxel-wise analysis showed a large number of white matter FA asymmetries including leftward asymmetry of the arcuate fasciculus and cingulum. The effects of age and sex on white matter FA asymmetry were minor compared to overall FA asymmetries. Small regions showed a significant effect of age or sex, due to the large sample, but this may not be relevant in practice. There was no significant interaction between age and sex. The results of our study demonstrate white matter asymmetry in healthy adults and suggest that white matter asymmetry is relatively stable during aging and not much different between males and females.

IgG4-related inflammatory pseudotumor of the trigeminal nerve: another component of IgG4-related sclerosing disease?

IgG4-related IPTs have been reported in various sites and may form part of the spectrum of systemic IgG4-related sclerosing disease. Some pseudotumors are clinically and radiologically indistinguishable from malignant tumors. We present the first case of an IgG4-related IPT of the trigeminal nerve diagnosed histopathologically without involvement of any of the common sites. The trigeminal nerve pseudotumor may represent a component of IgG4-related sclerosing disease.

Parasellar T2 dark sign on MR imaging in patients with lymphocytic hypophysitis.

BACKGROUND AND PURPOSE: MR imaging findings of LYH and pituitary adenomas are similar, but the therapeutic strategies are completely different. The purpose of this study was to evaluate sellar and parasellar MR imaging findings in patients with both diseases, as well as characteristic clinical findings. MATERIALS AND METHODS: Clinical findings, including endocrinologic study and MR images of 20 patients with LYH and 22 patients with pituitary adenoma, were retrospectively reviewed. We evaluated the MR images in relation to the following: 1) the PPHI on T1-weighted images, 2) thickened stalk (>3.5 mm), 3) pituitary symmetry, 4) pituitary enhancement pattern, 5) a dural tail, and 6) parasellar signal intensity on T2- and T1-weighted images. RESULTS: Between patients with LYH and those with pituitary adenoma, a significant difference was identified for the number of patients with loss of PPHI, thickened stalk, pituitary symmetry, homogeneous enhancement, and parasellar dark signal intensity on T2-weighted images by statistical analysis (Fisher exact probability test, P < .05). Among them, only parasellar dark signal intensity on T2-weighted images had no false-positive cases. CONCLUSIONS: The parasellar T2 dark sign can be a specific finding used to distinguish pituitary adenoma from LYH.

Natural history of true pancreaticoduodenal artery aneurysms.

Advances in non-invasive diagnostic techniques, such as CT and ultrasonography, have improved our ability to detect unruptured pancreaticoduodenal artery aneurysms. No definitive study evaluating the natural history of these lesions or their preferred method of treatment has been published. In this report, we describe five patients with eight unruptured true pancreaticoduodenal artery aneurysms followed without treatment. Of these patients, four had coeliac axis stenosis (n = 1) or occlusion (n = 3) and one had occlusion of the superior mesenteric artery. The mean diameter of the aneurysms was 12.0 mm (range 7-17 mm). The mean duration of follow-up was 29.4 months (range 6-57 months). There was no aneurysm rupture during a total of 147 patient-months (243 aneurysm-months) of follow-up. Of the eight aneurysms, three increased in size over the follow-up period. We conclude that the risk of rupture of true pancreaticoduodenal artery aneurysms might be lower than expected from the data on ruptured aneurysms; however, careful follow-up of untreated aneurysms is necessary.