P300 and contingent negative variation in migraine

We reviewed P300 and contingent negative variation (CNV) studies performed in migraine in order to identify their relevance in migraine and the role of neurophysiology in migraine. Publications available to us were completed by a Medline search. There is experimental and clinical evidence for loss of cognitive habituation in migraine which may serve as a specific diagnostic tool; therefore, we reviewed studies on migraine that analyzed habituation and lack of habituation by P300 and CNV, performing short-term habituation (STH) and long-term habituation (LTH). Finally, we described the two components of P300 (a and b) and of CNV (early and late wave) and the two abnormalities reported from the majority of studies on event-related potential in migraine: increased amplitude of average event-related potential and lack of habituation. These abnormalities are especially related to the early component characterizing orienting activity.     

Role of advanced 2 and 3-dimensional ultrasound for detecting prostate cancer

PURPOSE: We explored the clinical usefulness of spectrum analysis and neural networks for classifying prostate tissue and identifying prostate cancer in patients undergoing transrectal ultrasound for diagnostic or therapeutic reasons. MATERIALS AND METHODS: Data on a cohort of 215 patients who underwent transrectal ultrasound guided prostate biopsies at Memorial-Sloan Kettering Cancer Center, New York, New York were included in this study. Radio frequency data necessary for 2 and 3-dimensional (D) computer reconstruction of the prostate were digitally recorded at transrectal ultrasound and prostate biopsy. The data were spectrally processed and 2-D tissue typing images were generated based on a pre-trained neural network classification. We used manually masked 2-D tissue images as building blocks for generating 3-D tissue images and the images were tissue type color coded using custom software. Radio frequency data on the study cohort were analyzed for cancer probability using the data set pre-trained by neural network methods and compared with conventional B-mode imaging. ROC curves were generated for the 2 methods using biopsy results as the gold standard. RESULTS: The mean area under the ROC curve plus or minus SEM for detecting prostate cancer for the conventional B-mode and neural network methods was 0.66 +/- 0.03 and 0.80 +/- 0.05, respectively. Sensitivity and specificity for detecting prostate cancer by the neural network method were significantly increased compared with conventional B-mode imaging. In addition, the 2 and 3-D prostate images provided excellent visual identification of areas with a higher likelihood of cancer. CONCLUSIONS: Spectrum analysis could significantly improve the detection and evaluation of prostate cancer. Routine real-time application of spectrum analysis may significantly decrease the number of false-negative biopsies and improve the detection of prostate cancer at transrectal ultrasound guided prostate biopsy. It may also provide improved identification of prostate cancer foci during therapeutic intervention, such as brachytherapy, external beam radiotherapy or cryotherapy. In addition, 2 and 3-D images with prostate cancer foci specifically identified can help surgical planning and may in the distant future be an additional reliable noninvasive method of selecting patients for prostate biopsy.     

Assessment of adverse events associated with triptans--methods of assessment influence the results

BACKGROUND: A recent study conducted in triptan-naive migraine patients showed that tolerability was the second most important attribute of an acute treatment. However, the proportion of patients reporting side effects after any acute treatment may vary with regard to the method of assessment. OBJECTIVES: To contrast two methods of assessing adverse events (prompted and unprompted) in those with headache using triptans. METHODS: This study was conducted in two sites, a headache center in the United States, and a neurology office focusing on headache in Italy. We prospectively surveyed 415 adults with headache, who had been using the same triptan for at least 3 months. Participants were asked about their headache and treatment history. Subjects then completed a standardized questionnaire, assessing adverse events in two different ways. First, subjects were asked if they had any adverse events when using the triptan. After returning the first part of the questionnaire, subjects received a second form, where 49 possible adverse events were listed. We contrasted and correlated both sets of answers. RESULTS: Most patients (U.S.=74.9%, Italy=65.5%) reported no side effects in the unprompted questionnaire. However, most of them (U.S.=62.9%, Italy=54.1%) reported at least one side effect in the prompted questionnaire. Most patients that reported side effects in the unprompted questionnaire said they had just one adverse event, while most reported two or more side effects in the prompted questionnaire. Both in the unprompted and in the prompted questionnaires, most side effects were rated as mild or moderate. Interestingly, 31 (7.5%) subjects (pooling data from both sites together) graded their adverse events as severe in the prompted questionnaire, but had not self-reported them. CONCLUSIONS: (1) When assessing adverse events, the method of data collection may dramatically influence the results. (2) From those subjects who did not self-report adverse events after using a triptan, most of them will report positively if presented with a list of side effects.     

Comparison of theoretical scattering results and ultrasonic data from clinical liver examinations

A theoretical analysis of soft-tissue ultrasonic scattering has been used to formulate specific results describing spectral parameters for tissue characterization. Results are applicable to clinical liver examinations. Three spectral parameters are mathematically expressed in terms of acoustic attenuation and the effective sizes, concentrations, and relative acoustic impedances of tissue scatters. Results from a clinical data base are shown to agree well with analytical results for each spectral parameter. Agreement is found for: spectral shapes; effects of attenuation; and correlations between parameters. Images of three spectral parameters are presented and their gray-scale features are evaluated with reference to analytical results.     

Adaptive spectral strain estimators for elastography

In conventional elastography, internal tissue deformations, induced by external compression applied to the tissue surface, are estimated by cross-correlation analysis of echo signals obtained before and after compression. Conventionally, strains are estimated by computing the gradient of estimated displacement. However, gradient-based algorithms are highly susceptible to noise and decorrelation, which could limit their utility. We previously developed strain estimators based on a frequency-domain (spectral) formulation that were shown to be more robust but less precise compared to conventional strain estimators, In this paper, we introduce a novel spectral strain estimator that estimates local strain by maximizing the correlation between the spectra of pre- and postcompression echo signals using iterative frequency-scaling of the latter; we also discuss a variation of this algorithm that may be computationally more efficient but less precise. The adaptive spectral strain estimator combines the advantages of time- and frequency-domain methods and has outperformed conventional estimators in experiments and 2-D finite-element simulations.     

Early Poststroke Seizures

We define as early seizure (ES) those occurring within 7 days after stroke and late seizures those developing beyond 1 week after stroke. Seizures are well known to occur at the onset of intracerebral hemorrhage and serve as a clinical marker. Onset seizures may be focal or generalized, are usually brief, and are associated with loss of consciousness in the setting of hemorrhage. A similar concept of immediate seizure occurs in traumatic brain injury. Predictive factors of ES can be classified of general and neurologic origin. An important question is whether ES per se worsen prognosis and outcome. The viability of the penumbral region in animal models of focal ischemia is influenced by the peri-infarct depolarization waves. If this also is true in humans, seizures in the immediate poststroke period might worsen outcome. Recently, hypercholesterolemia has been associated with better functional outcome at 1 month after a first-ever stroke, and multivariate analysis studies have shown that mean cholesterol values were lower in patients with ES compared with controls.     

Early poststroke seizures

We define as early seizure (ES) those occurring within 7 days after stroke and late seizures those developing beyond 1 week after stroke. Seizures are well known to occur at the onset of intracerebral hemorrhage and serve as a clinical marker. Onset seizures may be focal or generalized, are usually brief and are associated with loss of consciousness in the setting of hemorrhage. A similar concept of immediate seizure occurs in traumatic brain injury. Predictive factors of ES can be classified of general and neurologic origin. An important question is whether ES per se worsen prognosis and outcome. The viability of the penumbral region in animal models of focal ischemia is influenced by the peri-infarct depolarization waves. If this also is true in humans, seizures in the immediate poststroke period might worsen outcome. Recently, hypercholesterolemia has been associated with better functional outcome at 1 month after a first-ever stroke, and multivariate analysis studies have shown that mean cholesterol values were lower in patients with ES compared with controls.     

75 MHz ultrasound biomicroscopy of anterior segment of eye

Very high frequency ultrasound (35-50 MHz) has had a significant impact upon clinical imaging of the anterior segment of the eye, offering an axial resolution as small as 30 microm. Higher frequencies, while potentially offering even finer resolution, are more affected by absorption in ocular tissues and even in the fluid coupling medium. Our aim was to develop and apply improved transducer technology utilizing frequencies beyond those routinely used for ultrasound biomicroscopy of the eye. A 75-MHz lithium niobate transducer with 2 mm aperture and 6 mm focal length was fabricated. We scanned the ciliary body and cornea of a human eye six years post-LASIK. Spectral parameter images were produced from the midband fit to local calibrated power spectra. Images were compared with those produced using a 35 MHz lithium niobate transducer of similar fractional bandwidth and focal ratio. The 75-MHz transducer was found to have a fractional bandwidth (-6 dB) of 61%. Images of the post-LASIK cornea showed higher stromal backscatter at 75 MHz than at 35 MHz. The improved lateral resolution resulted in better visualization of discontinuities in Bowman's layer, indicative of microfolds or breaks occurring at the time of surgery. The LASIK surface was evident as a discontinuity in stromal backscatter between the stromal component of the flap and the residual stroma. The iris and ciliary body were visualized despite attenuation by the overlying sclera. Very high frequency ultrasound imaging of the anterior segment of the eye has been restricted to the 35-50 MHz band for over a decade. We showed that higher frequencies can be used in vivo to image the cornea and anterior segment. This improvement in resolution and high sensitivity to backscatter from the corneal stroma will provide benefits in clinical diagnostic imaging of the anterior segment.