Objective To assess the diagnostic value of diffusion-weighted echo-planar MR Imaging (DWI) in ring-enhancing intracerebral lesions. Methods Magnetic resonance diffusion-weighted images of ninty-three patients presenting with ring-ehancing intracerebral lesions diagnosed by clinical or histopathologic findings were studied retrospectively, including 21 gliomas, 26 metastases, 13 pyogenic abscesses, 18 neurocysticercoses and 15 subacute intracerebral hematomas. The signal intensity ratio on diffusion-weighted images and exponential diffusion coefficient images was calculated respectively in ring walls, central contents, and perilesional edemas of ring-enhancing lesions, and normal contralateral cerebral parenchyma was used for comparison. ADC values of interest of lesions, contralateral cerebral parenchyma and CFS were calculated as well. Results In pyogenic abscesses and subacute intracerebral hematomas, the central content was always extremely hyperintense on diffusion-weighted images, and showed low ADCs[(0.56?0.20)?10~ -3 mm~2/s, (0.69?0.16)?10~ -3 mm~2/s, respectively]. On the other hand the central content of gliomas, metastases and neurocysticercoses was hypointense, and showed high ADCs [ (2.76?0.41)?10~ -3 mm~2/s, (2.31?0.39)?10~ -3 mm~2/s, (2.10?0.32)?10~ -3 mm~2/s, respectively]. The ADCs of the first two lesions were significantly lower than of the last three lesions (P

Objective To evaluate MR findings and clinical features in patients with spontaneous spinal epidural hematoma (SSEH). Methods Eight patients (5 men, 3 women; aged 16-50 years ) with SSEH underwent MR imaging during 1994-2001, including 7 cases without history of trauma or coagulation disorders and 1 case with history of hypertension. MR imaging was performed from 4 hours to 3 days after the onset of symptoms in all 8 patients with surgical and pathologic diagnosis. Results The hematomas were in lateral posterior or posterior epidural space, including 3 cases in cervical vertebra, 2 cases in thoracic vertebra, 2 cases in cervical and thoracic junction region, and 1 case in thoracic and lumbar part. The MRI confirmed an encapsulated hematoma caused by arteriovenous malformation in 1 case and two hematomas associated with disc herniation. The signal intensity of the hematoma varied with the hematoma age, but T 1-weighted images reflected its typical signal changes. Sagittal and coronal T 1- weighted images revealed isointense (7 cases) and slight high-intense (1 case) signal; Sagittal and axial T 2-weighted images revealed mixed-intensity (6 cases) and mixed high-intensity (2 cases). Conclusion MR imaging has an important value on localization, identification, and differential diagnosis of the lesion, therefore, it is the most helpful diagnostic tool for this condition.

Objective To analyze the imaging features of hepatic angiomyolipoma (HAML) on computed tomography (CT) and magnetic resonance imaging (MRI).Methods The imaging fingdings of 18 tumors which were pathologically diagnosed as HAML after surgery were analyzed retrospectively.Before operation,twelve and ten patients underwent CT and MRI non-contrast and dynamic enhanced scans,respectively,and 4 patients received both examinations.The imaging characteristics including the number,diameter,location,appearance of the lesions,plain and dynamic enhancement mode were analyzed.Results Eighteen HAML lesions were found in 18 patients with a diameter ranging from 1.5 cm to 17.2 cm (mean 5.3 cm).Five lesions manifested fatty content,and one showed hemorrhage and necrosis.Five HAMLs enhanced in a fast-in and fast-out mode,eleven in a fast-in and slow-out mode and two other lesions in an irregularly discrete mode.The arterial supply was found in 11 HAMLs in the hepatic arterial phase,all coming from intrahepatic arteries.Intratumoral vessels were observed in 12 HAMLs.Early draining veins to the hepatic vein (n =3) and portal vein (n =1) were detected in 4 HAMLs.One lesion demonstrated delayed enhancement in the pseudocapsule.Conclusion The detection of arterial supply and intratumoral vessels in a hypervascular hepatic tumor on contrast CT and MRI in a patient with a non-cirrhotic liver and normal AFP helps to make a diagnosis of HAML.

Attention deficit hyperactivity disorder (ADHD) is a common childhood neuropsychiatric disorder that has been linked to the dopaminergic system. This study aimed to investigate the effects of regulation of the dopamine D4 receptor (DRD4) on functional brain activity during the resting state in ADHD children using the methods of regional homogeneity (ReHo) and functional connectivity (FC). Resting-state functional magnetic resonance imaging data were analyzed in 49 children with ADHD. All participants were classified as either carriers of the DRD4 4-repeat/4-repeat (4R/4R) allele (n = 30) or the DRD4 2-repeat (2R) allele (n = 19). The results showed that participants with the DRD4 2R allele had decreased ReHo bilaterally in the posterior lobes of the cerebellum, while ReHo was increased in the left angular gyrus. Compared with participants carrying the DRD4 4R/4R allele, those with the DRD4 2R allele showed decreased FC to the left angular gyrus in the left striatum, right inferior frontal gyrus, and bilateral lobes of the cerebellum. The increased FC regions included the left superior frontal gyrus, medial frontal gyrus, and rectus gyrus. These data suggest that the DRD4 polymorphisms are associated with localized brain activity and specific functional connections, including abnormality in the frontal-striatal-cerebellar loop. Our study not only enhances the understanding of the correlation between the cerebellar lobes and ADHD, but also provides an imaging basis for explaining the neural mechanisms underlying ADHD in children.
Attention Deficit Disorder with Hyperactivity ; diagnostic imaging ; genetics ; pathology ; Brain ; diagnostic imaging ; Cerebellum ; diagnostic imaging ; Child ; Corpus Striatum ; diagnostic imaging ; Female ; Frontal Lobe ; diagnostic imaging ; Genotype ; Humans ; Image Processing, Computer-Assisted ; Magnetic Resonance Imaging ; Male ; Minisatellite Repeats ; genetics ; Neural Pathways ; diagnostic imaging ; Oxygen ; blood ; Receptors, Dopamine D4 ; genetics ; metabolism ; Rest