Visual function in Huntington's disease patients and presymptomatic gene carriers.

Disturbances of visual cognition, visuomotor performance, and visual memory have been described frequently in Huntington's disease (HD). Early stage visual abnormalities could contribute to these deficits. We evaluated visual processing in 20 control subjects who were non-gene carriers at risk for HD, nine presymptomatic gene-positive subjects, and eight subjects with a recent diagnosis of Huntington's disease. Visual perceptual tests of contrast sensitivity and motion discrimination were used to probe early stage visual processing. Extraocular movements were evaluated in a neurologic examination, and the Digit Symbol test was used to test visual motor performance. Contrast sensitivity did not differ among the three groups. Motion discrimination was impaired in HD subjects but not in the presymptomatic gene carriers when compared to gene noncarriers. Among gene carriers, impaired motion discrimination performance was associated with poorer Digit Symbol performance and extraocular abnormalities. These findings suggest that the early stages of HD are associated with disturbances of motion perception as well as disruptions of visual motor and ocular motor performance.     

Sclerosed liver hemangioma mimicking malignant tumor at MR imaging: Pathologic correlation

This case report illustrates atypical magnetic resonance (MR) imaging findings in a liver hemangioma mimicking a malignant lesion—lower signal intensity than cerebrospinal fluid on T2-weighted spin-echo images and lack of early enhancement on dynamic contrast material—enhanced gradient-echo images. Pathologic analysis demonstrated nearly total replacement of the vascular cavities by dense fibrous tissue. In this rare, sclerosed form, this lesion could not be defined as a hemangioma with MR imaging.     

Quantitative SPECT leads to improved performance in discrimination tasks related to prodromal Alzheimer's disease.

We investigated the impact of the quantitation and reconstruction protocol on clinical tasks. The performance of standard clinical reconstruction procedures in discrimination tasks related to the diagnosis of prodromal Alzheimer's disease (AD) was compared with the performance of a quantitative approach incorporating improved corrections for scatter, attenuation, intrinsic spatial resolution, and distance-dependent spatial resolution. METHODS: Seventeen normal controls (normal group), 56 subjects who did not have dementia, who did have memory problems, but who did not develop AD within 5 y of follow-up (questionable group), and 27 subjects who did not have dementia, who did have memory problems, and who did develop AD over the follow-up period (converter group) were considered in this study. (99m)Tc-hexamethylpropyleneamine oxime SPECT and MRI studies were performed for each subject at baseline. The standard quantitation protocol (STD), routinely used in our clinic, consisted of Compton window scatter correction followed by filtered backprojection with attenuation correction using a uniform attenuation map. In the improved quantitative approach (QUAN), projections were corrected for scatter by use of a general spectral method and reconstructed by use of ordered-subset(s) expectation maximization, incorporating corrections for collimator response and attenuation using both a uniform attenuation map (QUANunif) and a nonuniform attenuation map (QUANnonunif). Mean SPECT activity concentration and MRI volume were estimated for 7 structures: rostral anterior cingulate gyrus, caudal anterior cingulate gyrus, posterior cingulate gyrus, hippocampus, basal forebrain, amygdala, and the banks of the superior temporal sulcus. Data were analyzed by pairwise discriminant analysis, and performance in binary group discrimination was measured by correlated receiver-operating-characteristic analysis. RESULTS: The use of QUANnonunif yielded a small but systematic improvement in discrimination accuracy for normal versus converter groups (accuracy or area under the receiver-operating-characteristic curve [Az], 0.965), normal versus questionable groups (Az, 0.973), and questionable versus converter groups (Az, 0.881) compared with the results obtained with QUANunif (Az, 0.955, 0.962, and 0.866, respectively). Discrimination performance was significantly lower (P < 0.05) with STD than with QUAN in all 3 tasks (Az with STD, 0.906, 0.878, and 0.768, respectively). MRI volume estimation led to a lower overall performance in all 3 tasks than did QUANnonunif (Az with MRI, 0.947, 0.917, and 0.872, respectively). CONCLUSION: Improved quantitative image reconstruction with accurate compensation for scatter, attenuation, and variable collimator response led to significantly better performance in discrimination tasks related to the diagnosis of prodromal AD than did standard clinical reconstruction procedures. The use of a nonuniform brain attenuation map yields a small improvement in discrimination accuracy.     

Effect of Multiple Freeze-Thaw Cycles on Detection of Measles, Mumps, and Rubella Virus Antibodies

We investigated the effect of multiple freeze-thaw cycles on mumps, measles, and rubella virus serum antibody levels with whole-virus immunoglobulin G enzyme-linked immunoassays. Fresh serum samples from nine healthy adult volunteers were divided into six sets of five aliquots each. Samples were taken through a total of 10 freeze-thaw cycles and stored at 4°C until assayed. Each assay measurement was done in replicates of five, and the mean value was reported. After completing 10 freeze-thaw cycles, we found no clinically or statistically significant effect on measured antibody levels and found no discernible detrimental effect on the ability to measure these antibodies by enzyme-linked immunoassays.