Quantitative electroencephalographic characteristics of crack cocaine dependence.

This study replicates preliminary findings reporting a quantitative electroencephalographic (QEEG) profile of crack cocaine dependence in abstinence. All subjects (n = 52) met criteria for DMS-III-R cocaine dependence (in the form of crack), and were residing in a drug-free therapeutic community. Baseline QEEG evaluations were conducted at intake (5-10 days after last use of crack, and at follow-up (1 month after last reported use). Previous findings of significant excess of relative alpha power and deficit of absolute and relative delta and theta power were replicated in this expanded group. Abnormalities were greater in anterior than posterior regions, and disturbances in interhemispheric relationships were also observed. Further, QEEG showed little change in the interval between the first and second evaluations. This QEEG profile may reflect persistent alterations in neurotransmission as a possible consequence of chronic cocaine exposure.

Infective endocarditis caused by slow-growing, fastidious, Gram-negative bacteria.

In a review of endocarditis caused by fastidious, slow-growing gram-negative rods, similarities in the spectrum of disease overshadow differences among cases grouped by specific organisms. Cardiobacterium hominis, Actinobacillus actinomycetemcomitans and Haemophilus species usually seed previously damaged cardiac valves presumably during bacteremia from an upper respiratory site. The clinical presentation resembles that of Streptococcus viridans endocarditis and is usually subacute or chronic. Despite bacteriologic cure, severe CHF and/or systemic embolization frequently develops during or following the course of antibiotics, resulting in significant morbidity and a high mortality rate. This report of nine cases diagnosed at five hospitals in a 7-year period suggests that endocarditis due to these organisms is more common than previously appreciated and frequently goes unrecognized. This is probably due to a lack of attention to the requirements for culture of this group of bacteria with propensity for granular growth in broth. We have proposed specific cultural techniques appropriate to the search for these organisms in patients with apparent culture-negative endocarditis.

Haemophilus influenzae meningitis: the spectrum of disease in adults.

Fifteen cases of Haemophilus influenzae (HI) meningitis in adults occurring of Cleveland during the last 11 years are presented. The majority of patients had factors predisposing to infection such as otitis, pneumonia, diabetes or alcoholism. In addition, 7 of the 15 patients developed meningitis at various intervals following head trauma and neurosurgery, and 3 patients required dural repairs for CSF rhinorrhea. The diagnosis of meningitis may be difficult to establish resulting in delay in appropriate therapy in some cases. Nuchal rigidity was absent frequently; CSF lymphocytosis can be seen initially. The CSF Gram stain may be negative or the pleomorphic nature of the organism on Gram-stain may make distinction from other gram-negative organisms difficult. The majority of patients had meningitis due to non-Type B HI in contrast to previous reports of this illness in children and adults. One of our patients had beta-lactamase producing HI isolated from CSF. We believe that chloramphenicol should be included in the initial empiric therapy for adults with meningitis and gram-negative coccobacillary rods on Gram-stain or negative CSF Gram-stains.

Persistent QEEG abnormality in crack cocaine users at 6 months of drug abstinence.

The major objective of this study was to examine the persistence of abnormal quantitative EEG (qEEG) measures over a six month time interval in subjects in strictly supervised drug free residential treatment for crack cocaine dependence. Seventeen subjects were assessed with qEEG at five to 10 days, one month and six months following their last use of cocaine. No significant changes were noted over time in abnormal qEEG measures, which included deficits of absolute and relative power in the delta band and increased relative alpha power. The persistence of qEEG abnormality in crack cocaine withdrawal suggests a persistent neurobiologic alteration resulting from chronic cocaine exposure. The specificity of the qEEG findings is discussed, and an interpretation is suggested with reference to the hypothesis of neural sensitization in cocaine dependence.

Verification of electron beam therapy with conventional and storage phosphor images: preliminary experience.

Portal verification images were generated by the photon contamination in electron beams produced by a linear accelerator during treatment of patients receiving high-energy electron radiation therapy. Both conventional and storage phosphor methods yielded projection radiographs in which anatomy of the irradiated and surrounding tissue was demonstrated. Exposed phantoms were used to confirm that the images represent a true projection of the radiation field. A preliminary series of 22 cases was evaluated by two radiotherapists and judged subjectively to be of clinical value. Geometric error, or more importantly, the lack thereof, during high-energy electron treatments was easily confirmed with this method. In three cases, the treatment protocol was corrected based on the images obtained. Because the readout process of storage phosphor images allows for gain adjustments and post-processing, the images obtained with this method were found to delineate anatomy in the treated and surrounding tissues somewhat more consistently than could conventional images.

Scintigraphy versus pH probe for quantification of pediatric gastroesophageal reflux: a study using concurrent multiplexed data and acid feedings.

We performed 12 simultaneous scintigraphic and pH probe studies in children being evaluated for reflux to determine the ability of scintigraphic images in comparison to pH probe data to quantify gastroesophageal reflux in children and to identify an optimal scintigraphic framing interval. We used a multiplexor to synchronize exactly the scintigraphy and pH probe and an acid meal to avoid missing postprandial episodes with the pH probe. We reformatted the studies in both 60-sec and 10-sec images to compare the two framing intervals. The 60-sec images produced better agreement between pH probe and scintigraphy than the 10-sec images for both the number of reflux episodes and the duration of reflux. Of the 64 reflux episodes detected by either method at this coarser framing interval, scintigraphy detected 80%, the pH probe detected 63% and both methods concurrently detected 42%. Of the 681 60-sec images aggregated across patients, scintigraphy detected 55% of those with intraesophageal refluxate, the pH probe detected 96% and both tests concurrently detected 51%. Within patients, the number of positive scintigraphic images in the postprandial hour correlated with the number of images with pH < 4 during the same hour (p = 0.008, and p < 0.0001 if two patients with very rapid gastric emptying are excluded), but not with the results of the 24-hr pH probe study. A 1-hr scintigraphic study formatted in 60-sec frames provides a quantitative representation of postprandial gastroesophageal reflux for children, particularly if they do not have rapid gastric emptying.

Simultaneous acquisition of physiological data and nuclear medicine images.

A technique has been developed that allows the simultaneous acquisition of both image and physiological data into a standard nuclear medicine computer system. The physiological data can be displayed along with the nuclear medicine images allowing temporal correlation between the two. This technique has been used to acquire images of gastroesophageal reflux simultaneously with the intraluminal esophageal pH. The resulting data are displayed either as a standard dynamic sequence with the physiological data appearing in a corner of the image or as condensed dynamic images.

Quantitative SPECT imaging: a review and recommendations by the Focus Committee of the Society of Nuclear Medicine Computer and Instrumentation Council.

This article is a review of the physics principles, instrumentation and reconstruction methods behind SPECT imaging. Particular attention is paid to the mechanisms that can significantly affect the accuracy of a SPECT image. We describe instrumentation advances and reconstruction methods used to correct images to improve image quality and produce quantitative images. The clinical importance of improved image quality and quantitation are also reviewed.

The effects of a 3-day increase of ambient temperature on body temperature and REM sleep in an animal model of depression.

This study examined the effects of elevated ambient temperature (Ta) on body temperature (Tb) and rapid eye movement (REM) sleep in depressed and control rats. Previous studies have shown that elevations of Ta to the rat's thermoneutral zone of 29 degrees C produced an increase of REM sleep in control rats. In this study, 15 male Sprague-Dawley rats, seven saline control rats (SAL) and eight rats that were classified as depressed according to the chlorimipramine model of depression (CLI rats), were implanted for continuous Tb and polysomnographic recording and were exposed to two Ta's, 22 degrees C and 29 degrees C. CLI and SAL rats had significantly more REM sleep and a lower body temperature at 29 degrees C than at 22 degrees C. At 22 degrees C, CLI rats had significantly more REM sleep during the light period and a higher Tb in the light and dark periods than SAL control rats. At 29 degrees C, there were no significant differences in REM sleep or in Tb between CLI and SAL rats. Because human endogenous depression is associated with abnormal REM sleep and an elevated nocturnal Tb, these results give further support for the validity of the CLI model of depression and provide insight into the relationships among Tb, Ta, REM sleep and depression.

The effect of a 3-day increase of ambient temperature toward the thermoneutral zone on rapid eye movement sleep in the rat.

This study examined the effect of a 3-day increase of ambient temperature (Ta) from the usual room temperature of 22 degrees C to the rat's thermoneutral zone (TNZ) of 29 degrees C on rapid eye movement (REM) sleep. Other laboratories have reported that brief increases of Ta to the TNZ increased REM sleep and that long-term increases of Ta produced long-term increases of REM sleep. However, these studies were limited by the lack of controls for order effects or by restricted recording times. In the present study, which controlled for order effects, polysomnographic recordings for 12 male Sprague-Dawley rats were obtained 24 hours a day for 3 days at an ambient temperature of 22 degrees C and for 3 days at the TNZ of 29 degrees C. In all rats, REM sleep minutes and REM sleep percentage of total sleep time were significantly greater at the higher temperature than at the lower temperature. The increase in REM sleep at 29 degrees C was stable over the 3-day recording period. Prolonged increase of ambient temperature towards the TNZ is a simple, nonpharmacological method of producing a sustained, significant increase of REM sleep in the rat.

The effect of image processing on chest radiograph interpretations in a PACS environment.

The question of whether image processing affects a radiologist's diagnostic performance is becoming more important as the digital modalities proliferate. In the multi-observer study reported, the performance of radiologists who interpret a series of posteroanterior digitized chest images displayed on a high-resolution workstation, with and without a set of image processing options, is determined. These include brightness, contrast, reverse look-up tables (black-bone), and two edge enhancement options. Three hundred images were evaluated twice (once in each mode) by each of seven board-certified radiologists, who recorded their confidence ratings for the presence or absence of one or more of the following abnormalities: interstitial disease, nodule, and pneumothorax. The original, unprocessed digital image was available for reference for those sessions in which the processing options were available. With the exception of one reader, receiver operating characteristic (ROC) analysis showed no statistically significant difference between the two modes (with and without processing) for the detection of any of the different abnormalities by individual readers. Likewise, the group as a whole showed no significant difference (P less than .05) for detection of any of the three abnormalities between the two reading modes.

A model system and technique to study the effects of ultrasound irradiation on embryonic development.

To study the effects of ultrasound on development it is important to have a system which provides reliable results. We have designed a system which allows for reproducible irradiations of chick embryos in ovo. The irradiation system includes a heated sonation tank with ultrasound absorbers and a PC/AT computer-based data acquisition system for on-line monitoring of irradiations. The ultrasound detection microprobe and irradiation transducers were calibrated against an NBS traceable balance meter. An acoustic spacer was utilized to provide a more uniform profile of the irradiation beam. At the position of the embryo the ultrasound field geometry was determined. To maintain the chick embryo in its natural physiological state while minimizing ultrasonic reflections and standing-wave generation, two diametrically opposed windows were made in the eggshell along the ultrasound pathway and covered with polyethylene membranes. Using this irradiation system at intensity levels as high as 1.1 W/cm2 (spatial average, temporal average) for 10 min, the temperature rise is minimal.

An automatic seed identification technique for interstitial implants using three isocentric radiographs.

A technique for the automatic reconstruction of the spatial coordinates of seeds in an interstitial implant has been developed. Seed coordinates from three isocentric radiographs, an anterior-posterior film, and an orthogonal pair of films taken at gantry angles of +/- 45 degrees from the anterior-posterior direction are digitized and recorded in a random sequence. From this, the three-dimensional coordinates of the seeds in the implant are computed by matching the values of common coordinates along the axis of rotation. This rotate and match technique leads to an accurate and consistent identification and reconstruction of seeds with 90% of them within 2 mm of their actual location. These new computer routines have been added to an existing treatment planning system (AECL TP-11 treatment planning system, version 5A). We present our algorithm and technique along with clinical examples.

The use of storage phosphors for portal imaging in radiation therapy: therapists' perception of image quality.

Two drawbacks in quality of portal radiographs in radiation therapy are their low contrast and low spatial resolution. These are due to the low differential absorption of body tissues at therapeutic energies and to a relatively large radiation source. We used an experimental, high-contrast sensitivity storage phosphor imaging system (Eastman Kodak Co.) to produce portal images. The system consists of a storage phosphor detector, a high-contrast sensitivity laser scanner (12 bit), an image processing module, and a laser printer (12 bit). Patients undergoing radiation therapy treatments had both a conventional portal image and a storage phosphor image taken. Both were displayed side-by-side and were evaluated independently by three radiotherapists according to quality of information to verify the treatment field. Each of the three radiotherapists rated the storage phosphor images to be better (p less than 0.001) than the conventional images. However, rated improvements of low-contrast storage phosphor images of the pelvis and abdomen (40) were significantly lower than those of high-contrast (head, neck, and chest) images (53).

Prediction of treatment outcome in cocaine dependent males using quantitative EEG.

This study investigates the existence of outcome related neurophysiological subtypes within a population of abstinent cocaine dependent adults. We have previously reported and replicated the existence of a distinctive quantitative EEG (QEEG) profile in such a population, and demonstrated the persistence of this pattern at one and six month follow-up evaluations. This profile is characterized by significant deficits of absolute and relative delta and theta power, and excess of relative alpha power, as compared with age expected normal values. Abnormalities were greater in anterior than posterior regions, and disturbances in interhemispheric relationships were also observed. In the current study, 35 adult males with DSM-III-R cocaine dependence, were evaluated while residents of a drug-free residential therapeutic community, 5-15 days after last use of crack cocaine. Using multivariate cluster analysis, two neurophysiological subtypes were identified from the baseline QEEGs; Cluster 1 characterized by significant deficits of delta and theta activity, significant excess of alpha activity and more normal amounts of beta activity (alpha CLUS) and Cluster 2 characterized by deficits of delta, more normal amounts of theta and anterior excess of alpha and beta activity beta CLUS). No significant relationships were found between QEEG subtype membership and length of exposure to cocaine, time since last use of cocaine or any demographic characteristics. Further, no significant relationships were found between the commonly reported comorbid clinical features of depression and anxiety and subtype membership. However, a significant relationship was found between QEEG subtype membership and length of stay in treatment, with members of the alpha CLUS retained in treatment significantly longer than members of the beta CLUS.

Avoidance of artifacts on computerized tomograms by selection of appropriate surgical clips.

Surgical clips (metallic or plastic) are frequently used for hemostasis and tumor marking. This study evaluated the radiographic and computerized tomographic appearance of different clips and their relative interference with computerized tomographic scans. Metallic clips (stainless steel, tantalum, and titanium) can all be seen on plain radiographs. Tantalum clips caused extensive distortion on computerized tomographic scans which would interfere with scan interpretation. Both stainless steel and titanium clips resulted in much less artifact and interference on computerized tomographic scans. Recent studies have suggested that there may be some risk of torsion of stainless steel clips in nuclear magnetic resonance scanners resulting in tissue damage. Absorbable plastic clips cannot be seen on plain film but are visualized on computerized tomographic scans and do not appear to cause scan artifact. Overall, we recommend the use of either titanium hemostatic clips when tumor marking on plain film is required or plastic clips when tumor marking is less important.

Selected noble-gas partition coefficients.

The Ostwald solubility of 41Ar, 127,133Xe, N13N and CH3 18F in water, saline, blood, plasma, lipids, benzene and bone were measured in vitro. In addition the bone-blood partition coefficients for these gases were determined. For 41Ar, the bone-blood partition function is found to be 1.1 +/- 0.3, whereas for xenon the bone-blood partition coefficient is 0.41 +/- 0.1.

An in vivo technique for the measurement of bone blood flow in animals.

A new technique to measure the in vivo clearance of 41Ar from the bone mineral matrix is demonstrated following fast neutron production of 41Ar in bone via the 44Ca(n, alpha) reaction at 14.1 MeV. At the end of irradiation, the 41Ar activity is assayed with a Ge(Li) detector where sequential gamma-ray spectra are taken. Following full-energy peak integration, background and dead time correction, the activity of 41Ar as a function of time is determined. Results indicated that the Ar washout from bone in rats using this technique was approximately 16 ml (100 ml min)-1 and in agreement with other measurement techniques. For sheep the bone perfusion in the tibia was approximately 1.9 +/- 0.2 ml (100 ml min)-1.