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The facilitation of response known as the "gap effect" (a decrease of response latency), observed for saccades and antisaccades when attention is modulated prior to such eye movements, was studied in patients with schizophrenia and in controls. The hypothesis tested was whether patients would show a deficient attentional facilitation in response latency. Fifteen patients with schizophrenia and 17 healthy controls performed blocks of saccades and antisaccades in a "gap" condition and an "overlap" condition. Saccade and antisaccade response latencies as well as the error rate for antisaccades were measured for each subject. A similar gap effect (decrease in latency for the gap compared to the overlap condition) was present in the saccade task for patients and controls. In contrast the gap effect in the antisaccade task was absent in 50% of patients compared to none of the controls. This finding was interpreted as indicative of deficient preprocessing in antisaccade-specific cortical areas in schizophrenia (such as the prefrontal cortex), while visually guided saccade processing remained intact. Our results, in addition to many other recent findings, could lead to specific hypotheses on cortical dysfunction in schizophrenia.

Previous magnetoencephalography (MEG) studies in healthy right-handed subjects have shown activation in the left posterior lateral aspect of temporal lobe accompanied by sources in the supramarginal gyrus (Broadmann areas 21,22) during language comprehension tasks. We used the method of functional magnetic resonance imaging to determine whether a similar comprehension task in which participants had to discriminate between feminine and neuter abstract nouns elicited activation in the same regions of the temporal lobes. A baseline condition was also used that required participants to discriminate between two different pitch tones. All six subjects showed significant activity in left superior and middle temporal gyrus (Broadmann areas 21,22) and five of them showed maximum activation in this area. Our results are in agreement with those of the MEG studies, demonstrating the concordance of the two methods and the validity of this task.

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Background: Reaction Times (RTs) are slower and more variable in patients with schizophrenia. The only exception to this psychomotor slowing is for visually triggered saccades. In this study we explore a different parameter of the RT distribution, its shape in patients with schizophrenia and controls. Methods: RTs for visually triggered saccades were measured in 53 patients and 1089 control subjects to compute means and coefficients of variation. Then average cumulative RT distributions were derived for each group. Finally the RT distribution for each group was modeled as a linearly rising decision signal. Results: Mean RTs did not differ between patients and controls but RTs were more variable in the patient group and a shape difference in the average RT distribution was present. The model application led to the conclusion that the rate of rise of the decision was more unpredictable in the patient group. Conclusions: These results confirm the hypothesis that an information processing difference in schizophrenia, unrelated to psychomotor slowing, results in a shape difference of the RT distribution for simple visually triggered saccades. This difference might be linked to a specific neurophysiological substrate.

This review provides a description of the measurement methods, task definitions and measurement parameters in the study of smooth eye pursuit and saccade-antisaccade tasks in psychiatry. The large heterogeneity in task definitions and definitions of parameters and its potential impact on the large variability of the parameter measures is presented. Finally issues relating to data aggregation, practice effects and reliability of these smooth eye pursuit and saccade-antisaccade task performance measures are also discussed. The main conclusion of this review is that oculomotor function testing is still lacking standardization of methods, tasks and parameters affecting its usefulness in certain areas of psychiatric research. A future research program could derive a set of tentative recommendations for test standardization.

The aim of this study was to investigate the effect of hemodialysis on body composition assessment by dual-energy x-ray absorptiometry (DEXA). Seventeen patients with chronic renal failure who were on a regular hemodialysis schedule were studied. Body weight and body composition were assessed immediately before and approximately 1 hour after a typical hemodialysis session. Body weight was assessed by means of an electronic balance. Body composition measurements were made by DEXA. Whole-body and subtotal (head and neck excluded) analysis assessed the following parameters: body weight, bone mineral density (BMD), bone mineral content (BMC), and fat (FTM) and lean (LTM) tissue mass. BMC, FTM, and LTM were estimated separately for the trunk, arms, and legs. The mean body weight reduction after hemodialysis was 2.8 ± 1.1 kg (mean ± SD). Concerning whole-body analysis, no change was observed in mean BMC and FTM after hemodialysis. On the contrary, a significant reduction was observed in mean body weight as assessed by DEXA (before hemodialysis, 65.0 ± 11.4 kg; after, 62.2 ± 10.9 kg, P = .0003), as well as in mean LTM (before hemodialysis, 42.7 ± 9.4 kg; after, 39.7 ± 9.0 kg, P = .0003). Similar results were obtained from subtotal and regional analysis. Body weight changes as measured by the electronic balance exhibited a strong positive correlation with the changes in both body weight and LTM as assessed by DEXA (r = .989, standard error of the estimate [SEE] = 0.167 kg and r = .941, SEE = 0.382 kg, respectively, P < .0001). It is concluded that gravimetric changes induced by hemodialysis are highly correlated with LTM changes and are not associated with changes in BMC or FTM estimated by DEXA.

Bone mineral density (BMD) in postmenopausal women with breast cancer and the effect of tamoxifen administration on it has not been adequately studied. For this reason we investigated the long-term effect of tamoxifen on bone mineral density (BMD) of postmenopausal women with breast cancer.Three groups of postmenopausal women with histologically diagnosed breast cancer were studied. The first group consisted of 64 women, aged 48–79 years, who had not taken tamoxifen and their BMD was measured at the beginning of the study. The results were compared with those of 321 healthy postmenopausal women matched for age and years since menopause. 26 of the 64 women in the first group, aged 48–79 years, formed a second group and their BMD was measured before, 6 and 12 months after tamoxifen administration (20 mg daily). The third group consisted of 27 women, aged 48–75 years, who had been on tamoxifen therapy for 0.5–10 years (mean time 2.5 years) and their BMD was measured at the beginning of the study, 6 and 12 months later on tamoxifen therapy.It was found that BMD in postmenopausal women with breast cancer was decreased when compared to that of normal postmenopausal women (p < 0.001). BMD did not decrease in women with breast cancer when measured before, 6 and 12 months after tamoxifen therapy (p > 0.1) and in the women who were on long-term tamoxifen therapy and their BMD did not change, 6 and 12 months later (p > 0.1).It is concluded that postmenopausal women with breast cancer have lower BMD when compared to that of normal postmenopausal women and that tamoxifen does not increase the age-related bone loss in these women.

The purpose of this study was to estimate the radiation dose to which children are exposed during cardiac catheterizations for the treatment of ventricular and atrial septal defects. Radiation doses were estimated for 46 children aged 1–18 years. These children were treated for secundum atrial septal defects (ASD group) for perimembranous ventricular septal defects (VSD group) or underwent a routine diagnostic catheterization (diagnostic group). Thermoluminescent dosimeters (TLDs) were attached in locations, representing the lateral entrance dose, the posterior entrance dose, the thyroid dose, and the gonad dose, respectively. A dose area product (DAP) meter was also attached externally on the posterior-anterior (PA) tube to give a direct value in cGy cm2 for each procedure. The patient's entrance dose from the PA field ranged from 1.5 to 185.0 mGy for all patients, while the lateral entrance dose varied from 0.9 to 204 mGy. Radiation exposure to the thyroid and the gonads was found to vary from 0.4 to 8.3 and 0.1 to 2.1 mGy, respectively. The DAP meter recorded DAP values for the posterior tube, between 46 and 3,700 cGy cm2. The mean effective dose was found to be 7.7, 16.2, and 33.3 mSv for the diagnostic, the ASD, and the VSD group, respectively. Very strong correlation was found between the DAP values and the entrance radiation dose measured with TLDs. The mean entrance dose received from therapeutic cardiac catheterizations using the Amplatzer devices was found approximately twice the dose received from a diagnostic one. Even for the most complex procedures, the maximum entrance dose was at least 10 times lower than the threshold, associated with skin erythema. © 2005 Wiley-Liss, Inc.

Purpose: To study the efficacy of the integration of functional magnetic resonance imaging (fMRI) and diffusion tensor imaging tractography data into stereotactic radiosurgery clinical practice. Methods and Materials: fMRI and tractography data sets were acquired and fused with corresponding anatomical MR and computed tomography images of patients with arteriovenous malformation (AVM), astrocytoma, brain metastasis, or hemangioma and referred for stereotactic radiosurgery. The acquired data sets were imported into a CyberKnife stereotactic radiosurgery system and used to delineate the target, organs at risk, and nearby functional structures and fiber tracts. Treatment plans with and without the incorporation of the functional structures and the fiber tracts into the optimization process were developed and compared. Results: The nearby functional structures and fiber tracts could receive doses of >50% of the maximum dose if they were excluded from the planning process. In the AVM case, the doses received by the Broadmann-17 structure and the optic tract were reduced to 700 cGy from 1,400 cGy and to 1,200 cGy from 2,000 cGy, respectively, upon inclusion into the optimization process. In the metastasis case, the motor cortex received 850 cGy instead of 1,400 cGy; and in the hemangioma case, the pyramidal tracts received 780 cGy instead of 990 cGy. In the astrocytoma case, the dose to the motor cortex bordering the lesion was reduced to 1,900 cGy from 2,100 cGy, and therefore, the biologically equivalent dose in three fractions was delivered instead. Conclusions: Functional structures and fiber tracts could receive high doses if they were not considered during treatment planning. With the aid of fMRI and tractography images, they can be delineated and spared. Ó 2010 Elsevier Inc. fMRI, Tractography, Radiosurgery, Treatment planning, CyberKnife.

Dose distributions registered in water equivalent, polymer gel dosimeters were used to measure the output factors and off-axis profiles of the radiosurgical photon beams employed for CyberKnife radiosurgery. Corresponding measurements were also performed using a shielded silicon diode commonly employed for CyberKnife commissioning, the PinPoint ion chamber, and Gafchromic EBT films, for reasons of comparison. Polymer gel results of this work for the output factors of the 5, 7.5, and 10 mm diameter beams are ͑0.702Ϯ 0.029͒, ͑0.872Ϯ 0.039͒, and ͑0.929Ϯ 0.041͒, respectively. Comparison of polymer gel and diode measurements shows that the latter overestimate output factors of the two small beams ͑5% for the 5 mm beam and 3% for the 7.5 mm beams͒. This is attributed to the nonwater equivalence of the high atomic number silicon material of the diode detector. On the other hand, the PinPoint chamber is found to underestimate output factors up to 10% for the 5 mm beam due to volume averaging effects. Polymer gel and EBT film output factor results are found in close agreement for all beam sizes, emphasizing the importance of water equivalence and fine detector sensitive volume for small field dosimetry. Relative off-axis profile results are in good agreement for all dosimeters used in this work, with noticeable differences observed only in the PinPoint estimate of the 80% −20% penumbra width, which is relatively overestimated.

The aim of the study was to assess whether changes in the interposition of body compartments affect the results of body composition measurements by dual-energy x-ray absorptiometry (DEXA) in the fan-beam mode. Thirty healthy subjects underwent two sequential measurements: the first was performed in the supine position as described by the manufacturer, and the second in the prone position. Estimates of body composition were compared between the two measurements. Mean body weight did not differ between measurements ([mean ± SD] supine v prone, 68.561 ± 12.461 v 68.589 ± 12.469 kg). Mean bone mineral content (BMC) was lower in the prone position versus the supine position. When the head was excluded, this difference reached statistical significance (supine v prone, 1,738 ± 361 v 1,688 ± 380 g, P = .0001). The mean fat tissue mass (FTM) was lower and lean tissue mass (LTM) higher in the prone measurements. When the head was excluded, the mean FTM difference between the two measurements became greater (FTM supine v prone, 25.129 ± 10.445 v 24.030 ± 10.388 kg, P = .0001; LTM supine v prone, 37.309 ± 9.357 v 38.246 ± 9.150 kg, P = .0001). It is concluded that the positioning of the patient on the examination table affects DEXA body composition measurements by the fan-beam mode. This could imply a lack of accuracy of the method, which may be due to subtle changes in regional tissue depth and fat distribution caused by patient repositioning.

HMGCoA-reductase inhibitors may retard progression of coronary artherosclerosis, thereby reducing events and postponing PTCA. We investigated myocardial perfusion reserve (MPR) in patients on cholesterol lowering therapy and compared them with patients who underwent PTCA. Methods: 39 patients eligible for PTCA were included. 22 patients were randomized to atorvastatin 80 mg OlD (ator) and 17 underwent PTCA (PTCA). At baseline and after 6 months patients underwent NH3-PET imaging at rest and during dipyridamole for MPR. Intention to treat analysis was done for MPR in the region eligible for PTCA (culprit region). Results: Baseline characteristics were comparable. LDLchol decreased only in the ator-group, in the PTCA-group MPR in the culprit region improved signifcantly after 6 months compared to baseline (1.59+0.57 to 2.15_+0.72, p = 0.005, paired t-test), while no significant change was observed in the ator-group (1.64+0.55 to 1.73+.46, p=NS). Conclusion: In CAD patients with high grade stenosis eligible for PTCA, MPR in the culprit-region increased significantly after PTCA. Whether this has implications for clinical outcome is under investigation. 43.31 REVISE I;tEDISIRIBUrlON IN CORONAt~Y AITfERY DISEASE PATIEN]S. CORi~ELAIION WItH CLINICAL ANGIOGI~APHIC SCINTIGRAPHIC AND ERGOMEII~IC VAI;tlABLES. A. An1,onopoulos, S, Arveni1,okis, Th.

This study was designed to assess the usefulness of the changes in left ventricular (W) systolic time intervals after phenylephrine administration for detecting highrisk patients soon after acute myocardial infarction by correlation with the angio#aphic and ventriculographic findi-. The procedure was performed in 76 consecutive w tients (group I) on the fourth postinfarction day and in 12 normal subjects (-up II) free of core nary artery disease. In 20 patients with LV ejection fraction 140% (subgroup IA) the preejection period (PEP)/LV ejection time (EQ ratio increased from 0.410 -c 0.107 to 0.525 * 0.102 (p = 0.01) after phenylephttne, whereas in the remaining 56 patients (subgroup IB) with LV ejection fraction MO% and in the 12 normal subjects the PEP/H/m increased nonsignificantly.

The prototype of a stereotactic collimator set developed in our department is evaluated for clinical use. This set consists of three cylindrical blocks mounted on a tray which slides in the wedge insert of a Siemens Primus accelerator. Each block has a collimating hole along its long axis to produce radiation fields of circular cross-section at the isocentre plane with diameters of 15 mm, 20 mm and 25 mm. Different geometric and dosimetric quality assurance tests were performed and results are found within the limits set for stereotactic radiotherapy. Dosimetry results measured using Kodak EDR-2 radiographic film and a pinpoint ion chamber also show good agreement with corresponding results calculated by Monte Carlo simulation of the linear accelerator head and the collimators. Measured dosimetry data were used to adapt a conventional PLATO treatment planning system for stereotactic radiotherapy using the prototype collimator set. Treatment planning system calculations and film measurements for treatment of an intracranial lesion in an anthropomorphic head phantom using coplanar 180˚arcs are compared and found to agree within 2 mm. This supports the accuracy of dose delivery using the prototype stereotactic collimators. Despite their increased penumbra (2.5-3.5 mm relative to 2-2.5 mm for commercially available collimators) the ease of construction makes the proposed stereotactic collimators an interesting alternative for accomplishing cost effective stereotactic treatments.

Background: Thallium-201 (201Tl) reinjection after conventional redistribution imaging is a standard procedure, resulting in enhanced 201 Tl redistribution which is compatible with viable myocardium. Although this method significantly improves identification of viable myocardium, it increases the investigation time by approximately 1 h. Thus, this technique is suboptimal from the standpoint of patient convenience, since its routine performance may be impractical in a high-volume nuclear medicine laboratory.Hypothesis: This study was undertaken to evaluate the efficacy of an early 201Tl reinjection and imaging protocol in combination with sublingual nitroglycerin, to detect myocardial ischemia and/or viability, and to reduce the need for conventional (4 h) redistribution imaging.Materials and Methods: In this study, 62 consecutive coronary patients, referred for the detection of possible myocardial ischemia and/or viability, were involved (mean age 55 years, range 41-70). Of those, 50 had previous angina attacks, with 42 having a history of previous myocardial infarction; 10 patients had coronary artery bypass grafting; and the remaining 2 had atypical chest pain. Immediately after the completion of the initial postexer-cise imaging, 0.3 mg sublingual nitroglycerin followed by the reinjection of 1 m Ci of 201Tl were administered, and two further sets of images were acquired 1 h and 4h later.Results: In each set of i mages, a total of496 segments were analyzed. On postexercise imaging, 305 (61%) segments demonstrated defects of which 198 (65%) showed enhanced thallium uptake, 97 (32%) did not change, and 10(3%) showed reverse redistribution on 1 h reinjection imaging (IRI). Of the 97 persistent defects, only 17 (6%) showed fill-in of 201 Tl on 4 h redistribution imaging (CRI), while 12 (4%) segments showed reverse redistribution. On the other hand, after analyzing the 62 patients of the 1 h IRI, 17 (27%) remained unchanged while in only 1 patient (6%) of 17 the diagnosis changed from myocardial necrosis to ischemia after analysis ofthe 4h CRI.Conclusion: These results indicate that early postexercise reinjection of 201Tl in combination with sublingual nitroglycerin followed by l h image acquisition may prove useful for a comprehensive and convenient assessment of myocardial ischemia and/or viability.

In this study the effect of different mammographic screen-film combinations on image quality and breast dose, and the correlation between the various image quality parameters, breast dose and the sensitometric parameters of a film were investigated. Three Agfa (MR5-II, HDR, HT), two Kodak (Min-R M, Min-R 2000), one Fuji (AD-M), one Konica (CM-H) and one Ferrania (HM plus) single emulsion mammographic films were combined with three intensifying screens (Agfa HDS, Kodak Min-R 2190 and Fuji AD-MA). The film characteristics were determined by sensitometry, while the image quality and the dose to the breast of the resulting 24 screen-film combinations were assessed using a mammography quality control phantom. For each combination, three images of the phantom were acquired with optical density within three different ranges. Two observers assessed the quality of the 72 phantom images obtained, while the breast dose was calculated from the exposure data required for each image. Large differences among screen-film combinations in terms of image quality and breast dose were identified however, that, could not be correlated with the film's sensitometric characteristics. All films presented the best resolution when combined with the HDS screen at the expense of speed, and the largest speed when combined with the AD-MA screen, without degradation of the overall image quality. However, an ideal screen-film combination presenting the best image quality with the least dose was not identified. It is also worth mentioning that the best performance for a film was not necessarily obtained when this was combined with the screen provided by the same manufacturer. The results of this study clearly demonstrate that comparison of films based on their sensitometric characteristics are of limited value for clinical practice, as their performance is strongly affected by the screens with which they are combined.