CT and 18F- FDG-PET-CT Findings in Secondary Adrenal Lymphoma with Pathologic Correlation.

RATIONALE AND OBJECTIVE: To evaluate computed tomography (CT) and positron emission tomography-computed tomography (PET-CT) imaging manifestations of lymphomas secondarily involving the adrenal gland. MATERIALS AND METHODS: Seven patients (Five men, two women; median age [range], 66 years [34-75 years]) with pathologically proven adrenal lymphoma were assessed retrospectively. Clinical findings, prior history of lymphoproliferative malignancy, CT (n = 7) and fludeoxyglucose positron emission tomography-computed tomography (18F-FDG-PET-CT) (n = 6) features were analyzed. RESULTS: Six cases were diffuse large B-cell lymphoma, and one case was peripheral T-cell lymphoma. The longest diameter of the lesions ranged from 3.2 to 6.6 cm (median 4.3 cm). Six lesions were well-defined and one lesion was ill-defined. In five cases, an adreniform shape was preserved. No lesions contained fat, calcification or hemorrhage. Two lesions had necrosis on CT. Median (range) unenhanced CT density of six lesions was 31.8 (29.2-35.2) Hounsfield units. Following administration of IV contrast media (n = 6), three lesions enhanced homogenously whereas three enhanced heterogeneously. The median increase in attenuation was 35.1 Hounsfield units. Two patients had 15-minute delayed CT and they both demonstrated limited wash-out consistent with nonadenoma. Six patients had fludeoxyglucose positron emission tomography-computed tomography(18-F-FDG-PET-CT) and all lesions were fludeoxyglucose (FDG) avid with a median SUVmax of 18.6 (range: 10.3-49.2). CONCLUSION: Secondary adrenal lymphomas usually manifest as, large (>3 cm), well-defined, homogenously or slightly heterogeneously enhancing masses on CT with preserved adreniform shape. These lesions tend to show limited wash-out and high fludeoxyglucose (FDG) uptake.

Quantitative Mapping of Human Brain Vertical-Occipital Fasciculus.

PURPOSE: The vertical-occipital fasciculus (VOF), historically named as "the fasciculus occipitalis verticalis of Wernicke," has been recently brought to the attention of the neuroscience community. In this study, we delineated and quantified this tract with deterministic diffusion tensor imaging protocol. METHODS: Five (all males aged 24-37 years) and 10 (7 males and 3 females aged 20-51 years) right-handed healthy subjects were studied with 1 and 2 mm DT-MRI data sets, respectively. The DTI attributes of this pathway along with its cortical representation (Brodmann areas) were presented in standard Montréal Neurological Institute space. Nearby pathways such as inferior fronto-occipital (IFOF) and inferior longitudinal fasciculi (ILF) were used as reference pathways. RESULTS: The total volume of VOF has been found to be approximately .8-1% of whole brain in both data sets. The fractional anisotropy and axial diffusivity of this tract have been found to be relatively 10-15% lower than adjacent pathways such as IFOF and ILF in both data sets. Although IFOF and ILF showed somewhat leftward asymmetry in diffusivity, no right-left asymmetry has been observed in VOF. CONCLUSION: We believe that our work will pave the way for future imaging studies investigating VOF in different conditions such as stroke, traumatic brain injury, and multiple sclerosis.

Diffusion tensor imaging of the human cerebellar pathways and their interplay with cerebral macrostructure.

Cerebellar white matter (WM) connections to the central nervous system are classified functionally into the Spinocerebellar (SC), vestibulocerebellar (VC), and cerebrocerebellar subdivisions. The SC pathways project from spinal cord to cerebellum, whereas the VC pathways project from vestibular organs of the inner ear. Cerebrocerebellar connections are composed of feed forward and feedback connections between cerebrum and cerebellum including the cortico-ponto-cerebellar (CPC) pathways being of cortical origin and the dentate-rubro-thalamo-cortical (DRTC) pathway being of cerebellar origin. In this study we systematically quantified the whole cerebellar system connections using diffusion tensor magnetic resonance imaging (DT-MRI). Ten right-handed healthy subjects (7 males and 3 females, age range 20-51 years) were studied. DT-MRI data were acquired with a voxel size = 2 mm × 2 mm × 2 mm at a 3.0 Tesla clinical MRI scanner. The DT-MRI data were prepared and analyzed using anatomically-guided deterministic tractography methods to reconstruct the SC, DRTC, fronto-ponto-cerebellar (FPC), parieto-ponto-cerebellar (PPC), temporo-ponto-cerebellar (TPC) and occipito-ponto-cerebellar (OPC). The DTI-attributes or the cerebellar tracts along with their cortical representation (Brodmann areas) were presented in standard Montréal Neurological Institute space. All cerebellar tract volumes were quantified and correlated with volumes of cerebral cortical, subcortical gray matter (GM), cerebral WM and cerebellar GM, and cerebellar WM. On our healthy cohort, the ratio of total cerebellar GM-to-WM was ~3.29 ± 0.24, whereas the ratio of cerebral GM-to-WM was approximately 1.10 ± 0.11. The sum of all cerebellar tract volumes is ~25.8 ± 7.3 mL, or a percentage of 1.6 ± 0.45 of the total intracranial volume (ICV).