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A set of fiducial markers for use in the alignment of MR, CT and SPET images is presented. The marker system consists of individually produced imprints of the external auditory meatus, a pair of plastic spectacle frames and three fiducial markers. The markers are filled with a suitable contrast agent, fixed into the imprints and screwed onto the spectacle frame just before examination. The reproducibility in positioning the marker system on the patient was evaluated by repeated MRI examinations of a volunteer. The fiducial markers could be repositioned with an accuracy of less than +/- 1.6 mm in the left-right and anterio-posterior directions and +/- 1.9 mm in the cranio-caudal direction (95% confidence interval). The marker system is inexpensive and easy to produce, taking less than 20 min to produce on the ward. Only a few minutes are required to fix the system prior to examination. It is comfortable for the patient, even during long examinations. In cases lacking visible intrinsic structures and external contours, fiducial markers provide a good means of alignment for image fusion. The marker system described here for the alignment of SPET, CT and MR images can be used on a routine basis without the invasive fixation of fiducial markers.

A growing body of evidence points out the potential role of inflammatory mechanisms in the pathophysiology of ischaemic brain damage. We have recently demonstrated that stroke patients display an intrathecal production of proinflammatory cytokines, such as IL-1beta and IL-6 already within the first 24 h after the beginning of symptoms (Tarkowski et al., 1995). The aim of the present study was to investigate patterns of local inflammatory responses as a consequence of acute stroke. Thirty stroke patients were studied prospectively on days 0-3, 7-9, 21-26 and after day 90 with clinical evaluations, radiological assessments and analysis of cerebrospinal fluid (CSF) cytokine levels. In addition, 15 healthy control CSF samples were used. Significantly increased CSF levels of IL-8, granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-10 were observed early during the stroke with a peak on day 2 for the proinflammatory cytokines IL-8 and GM-CSF, and on day 3 for the immunoregulatory cytokine IL-10. Patients with a brain infarct predominantly located in the white matter showed significantly higher levels of IL-8 in CSF than patients with an infarct mainly located in the grey matter. Also, high levels of intrathecal tumour necrosis factor-alpha (TNF-alpha) were associated with the presence of white matter disease. Our study demonstrates an intrathecal production of proinflammatory and immunoregulatory cytokines in patients with stroke, supporting the notion of localized immune response to the acute brain lesion. A better understanding of the inflammatory response in stroke may lead to new treatment strategies.

Purpose: To assess the diagnostic efficacy, safety and tolerability of mangafodipir trisodium (MnDPDP, Teslascan) in MR imaging of the liver., Material and Methods: Eighty-two patients from 4 centres underwent MR imaging with pre-contrast sequences including T1-weighted SE and GRE, and T2-weighted turbo SE sequences. MnDPDP at a dose of 5 mumol/kg b.w. was administered by slow i.v. infusion, and 20-60 min after infusion the T1-weighted SE and GRE sequences were repeated. Diagnostic efficacy was evaluated by counting the number of lesions and by evaluating whether more information for lesion characterisation was available in post-contrast images. Safety and tolerability were assessed by recording adverse events and infusion-related discomfort., Results: Significantly more lesions were found in MnDPDP-enhanced T1-weighted SE and GRE images than in unenhanced images of the same sequences. More lesions were also found in these images compared with T2-weighted images at a level of marginal significance. More information was obtained from MnDPDP-enhanced images in 40 cases. Mild to moderate adverse events were experienced by 17% of the patients., Conclusion: MnDPDP-enhanced images can improve lesion detection in the liver and are helpful for lesion characterisation. To obtain optimal diagnostic information of liver lesions T2-weighted images are also valuable. MnDPDP is a safe contrast agent for MR imaging of liver lesions.

Anatomical and neurological correlates of visuospatial neglect were studied in 53 patients with a CT-documented right hemisphere stroke. Evidence of neglect at the acute stage poststroke was strongly related to large lesions involving the middle temporal gyrus and/or the temporo-parietal paraventricular white matter. Thus, out of 18 patients with evidence of visuospatial neglect at the acute stage, 12 showed a lesion in the middle temporal gyrus and/or the deep temporo-parietal white matter. Among the 35 patients that failed to show visuospatial neglect, only one patient had a lesion within these areas. Comparing those patients who recovered from neglect with those that did not, a high correlation was found between persisting neglect and a lesion involving the paraventricular white matter in the temporal lobe. On the basis of above findings, it was suggested that a simultaneous damage to the cortico-thalamic system for regulation of arousal and to the neural systems mediating visual orienting, is likely to be followed by persisting neglect symptoms.

The purpose of this study was to analyse factors for interobserver disagreements in two scales used for the assessments of the amount of blood in subarachnoid space (Fisher grading) and of acute hydrocephalus on computerized tomographic (CT) scans. The assessments made by four neuroradiologists on 59 CT scans obtained in the acute stage after subarachnoid hemorrhage were analysed by a statistical method by Svensson and Holm. This method permits the separation of the inter-observer disagreements in their random and systematic components. The overall consistency of the assessments was significant (p < 0.0005) but the neuroradiologists disagreed on half of the CT-scans. The kappa values were 0.50-0.63. The analysis showed that the main reason for disagreements was systematic inter-observer differences in their use of the clinically most important parts of staging, i.e. subarachnoid clot or intraventricular blood (Fisher grading) and too low categories (hydrocephalus). The main conclusion from this study is that the proper remedy for Fisher grading and for grading of hydrocephalus is a sharpening of the criteria of specific category levels and given this improvement both grading systems will show a high level of reliability.

The use of magnetic resonance imaging (MRI) has resulted in the detection of an increasing number of children with an apparently leukodystrophic white matter. Laboratory tests and the clinical presentation, however, often do not correspond to any known entity and the course is sometimes not progressively deteriorating. Such children with white-matter changes and no known diagnosis were the subject of this Swedish multicentre study, in which MRI findings and clinical data from 100 children considered to have white-matter abnormalities were assessed during the period 1992-1995. At re-evaluation of MR images by an established "white-matter group" of neuroradiologists, paediatric neurologists, neurologists and neurochemists, the MRI signal of the white matter was considered normal in eleven children and eleven had mainly a grey matter affection. Of the remaining 78 children with white matter abnormalities, a diagnosis was found in 32, but in 46 children no diagnosis could be established. A progressive downhill course characterised 17, probably representing hitherto undefined types of leukodystrophies. Five children had a relapsing-remitting course, and in 11 it was difficult to establish whether the course was progressive or stationary. The disease was non-progressive in 13. This group of non-leukodystrophic white-matter changes obviously represents maldevelopments of myelin formation, thus dys- or hypomyelination rather than demyelination.

The synthetic immunomodulator Linomide, a quinoline-3-carboxamide, has a profound inhibitory influence in several experimental autoimmune diseases, including acute and chronic experimental allergic encephalomyelitis. In a double-blind trial, 31 patients with relapsing-remitting multiple sclerosis were randomized to oral doses of 2.5 mg Linomide or placebo once a day for six months. Fourteen patients receiving Linomide and 14 receiving placebo completed the trial, and the results were based on this population. The mean number of active (new and enlarged T2 weighted) lesions per monthly MRI scan was 1.37 in the patients receiving Linomide and 4.22 in the patients receiving placebo (p = 0.043). The percentage of scans with active MRI lesions was lower in the Linomide-treated group (p = 0.0064). When neurologic deficit was assessed by the Regional Functional Scoring System (RFSS), the Linomide group showed an improvement of 1% of the maximal RFSS range and the placebo group a deterioration of 0.2% (p = 0.14). There were three patients with relapses in the Linomide-treated group and six in the placebo group (p = 0.22). A slightly decreased proportion of natural killer cells in cerebrospinal fluid and peripheral blood was noted in the Linomide group. A severe adverse event of pleuropericarditis occurred in one of the Linomide-treated patients. The most frequent adverse event was musculoskeletal pain, of mild to severe degree, which tended to diminish after three months on Linomide therapy.

Image quality in preimplant computerized tomography (CT) examinations made with different radiation doses (40 to 280 mAs) and scanning modes (standard and helical axial, 15-degree angled, and frontal) and in conventional spiral tomography (Scanora) was compared. Mandibular canal and alveolar bone crest visibility was evaluated in images from mandibular jaw segments. Visibility was unaffected by radiation dose in CT examinations except in frontal scanning, where a small actual difference was statistically significant. Differences among CT scanning modes and between CT and conventional spiral tomography were highly significant. Low-dose mandibular preimplant tomography can be performed with CT using lower-than-normal radiation doses or with conventional spiral tomography.

Purpose: The purpose of this study was to examine the potential of 31P-MRS (MR spectroscopy) in the pre- and postoperative evaluation of patients referred for endarterectomy., Material and Methods: Nine patients with unilateral, hemodynamically significant stenosis in the region of the common carotid bifurcation were examined pre- and post-operatively with CT, SPECT (regional cerebral blood flow), transcranial Doppler, and duplex sonography, and they also underwent neuropsychologic investigation. Phosphorus-31 MRS of each hemisphere was performed before and 27-148 days after surgery. The relative concentrations of phosphomono- and -diesters, inorganic phosphate, phosphocreatine, and ATP were estimated., Results: No definite changes in concentrations could be detected for any of the metabolites., Conclusion: The lack of changes was probably due to well-functioning collaterals and to the partial volume effect, whereby changes in a focal region are hidden when larger volumes are studied.

Purpose: This Swedish multicenter trial was performed on patients with known or suspected lesions of the CNS for which an MR examination using a contrast medium was indicated. A total of 8 MR centers participated in the study to establish the safety and efficacy of Omniscan (gadodiamide injection) in clinical routine using a standard dose of 0.1 mmol Gd/kg b.w., Material and Methods: Seven hundred adult patients who had been referred for MR investigation of suspected CNS lesions were included in the study. Since most patients were examined on an outpatient basis, it was decided to use an explicit questionnaire regarding adverse events that developed within 24 h after examination. The efficacy evaluation involved comparisons of detectability, delineation, and number of lesions before and after injection of Omniscan., Results: No serious or unexpected adverse event was found. There were a total of 70 (10.2%) patients with adverse events, excluding those judged not to be contrast media-related. However, only 15 patients (2.2%) had adverse events that possibly or probably were related to the contrast medium. Usually, the symptoms were headache, dizziness, abnormal taste, and nausea. Two patients complained of itching, but only one developed urticaria. The efficacy was similar to that of other currently used Gd-based MR agents. Lesions were more often seen on T2-weighted images, but the contrast medium improved lesion delineation, contributing to higher certainty in diagnosis, and provided more confidence in excluding suspected abnormality., Conclusion: Omniscan was found to be a safe and clinically valuable contrast medium for MR imaging of the CNS.

High-resolution signal profiles obtained with a test phantom were used in this study to evaluate the volume-selection performance of an implementation of ISIS (Image Selected In vivo Spectroscopy). The phantom simulated the brain with regard to volume and loading of coil. A remotely controlled, movable signal source inside the phantom was filled with orthophosphoric acid. Signal profiles of the volume of interest (VOI) were measured in three perpendicular directions. Special interest was focused on the transition zones, the position of the profiles, and the effects of off-resonance and T1 smearing. The transition zones were on average 5.6 mm wide and the full width at half maximum (FWHM) was 35 mm for a VOI of 40 x 40 x 40 mm3. The positions of the centre of the signal profiles were x = 3.2, y = -0.7 and z = 3.3 mm off-centre. The deviation of the volume position could be explained by off-resonance effects during imaging and spectroscopy. These data illustrate the importance of detailed knowledge of the volume-selection performance when attempting precision measurements using image-guided in vivo MRS.

Background and Purpose: Symptoms interpreted as unilateral disturbances of autonomic function, such as coldness, dryness, sweating, and trophic changes, are well known but incompletely understood clinical problems after stroke. The present study provides data related to the incidence and mechanisms behind such symptoms., Methods: Temperature perception thresholds, skin temperatures, evaporation rates, and skin blood flow responses were measured bilaterally in 37 stroke patients aged 58 +/- 13 years (mean +/- SD) and in a control group of 15 patients aged 64 +/- 15 years with a single transient ischemic attack., Results: Of the 37 stroke patients, 43% reported a sensation of coldness in the contralesional side of the body. Basal skin blood flow and temperature were relatively lower in the contralesional side. There was an excess of evaporation in the contralesional side after brain stem lesions and in the ipsilesional side after hemispheric lesions. Vasomotor reflex asymmetries occurred in 34% of the patients and were due to weak vasodilator or vasoconstrictor reflexes in the ipsilesional side. These abnormalities correlated significantly to sensations of unilateral coldness, hypalgesia, and thermohypesthesia in the contralesional side and anatomically to lesions in spinothalamo-cortical pathways., Conclusions: Focal central nervous system lesions due to stroke may result in symptoms and measurable evidence of unilateral disturbance of skin sympathetic function. Vasomotor asymmetries are probably due to lesions of vasomotor pathways descending uncrossed. Subjective coldness may be due to disturbed central processing.

Background and Purpose: We have previously demonstrated that stroke influences systemic immune responses. The aim of the present study was to investigate patterns of local inflammatory response as a consequence of acute stroke., Methods: Thirty stroke patients were studied prospectively on days 0 to 3, 7 to 9, 21 to 26, and after day 90 with clinical evaluations, radiological assessments, and analysis of serum and cerebrospinal fluid cytokine levels., Results: Significantly increased levels of interleukin-6 (IL-6) in cerebrospinal fluid (P < .001) were observed in virtually all patients studied compared with healthy control subjects. This increase was observed during the whole observation period but was significantly more pronounced within the first days after stroke onset, with a peak level on days 2 and 3. This initial increase was significantly correlated (r = .65, P = .002) with the volume of infarct measured by MRI 2 to 3 months later. Serum levels of IL-6 in stroke patients were significantly lower than cerebrospinal fluid levels of IL-6 (P = .013) and did not display any significant correlation to the size of the brain lesion. Also, increase in intrathecal but not systemic production of IL-1 beta was observed early during the stroke. Only minor increases of cerebrospinal fluid interferon-gamma levels were observed in two patients., Conclusions: Our study demonstrates an intrathecal production of IL-6 and IL-1 beta in patients with stroke, supporting the notion of localized inflammatory response to acute brain lesion. In addition, the significant correlation between early intrathecal production of IL-6 and the subsequent size of the brain lesion can be used as a prognostic tool, predicting the size of the brain damage before it is possible to accurately visualize it with radiological methods.

In vivo MR spectroscopy (MRS) requires some kind of volume selection method to be able to measure the signal from a selected part of the body. To be able to interpret the spectra correctly, the quality of the volume selection must be investigated for each new MRS application using phantom measurements. A new phantom, especially suitable for precision measurements of the volume selection performance, is presented. It contains a small, remotely controlled signal source placed inside a larger vessel. This principle can be applied to various body regions, coil types and nuclei. The measurement conditions are close to the clinical situation. The phantom does not have to be repositioned during a signal profile measurement and the signal contribution from each point along the profile is determined regarding sign and amplitude.

An investigation regarding possible artefacts from dental filling materials in MR imaging is presented including 9 types of such materials from various manufacturers. Freshly extracted teeth were prepared and the filling materials were handled according to manufacturers' instructions. The teeth were encapsulated into a gel phantom based on de-ionized water, Ni (NO3)2 and polysaccharide agarose powder. The investigation was performed with a standard head coil and a 1.5 T MR unit. Images acquired with various combinations of parameters from different sequences were visually analysed regarding possible artefacts. The investigation showed that only one of the materials caused significant artefacts. The gel phantom was found to be a valuable means for examination of artefacts from small samples, and can be recommended as a standard technique for this purpose.

The addition of sodium to nonionic contrast media has reduced the incidence of arrhythmias in animal models. The influence on cardiac function and safety of sodium addition to the nonionic contrast medium iohexol (Omnipaque) was studied in a randomized, double-blind trial in patients undergoing cardioangiography. Fifty-nine patients received iohexol 350 mg I/ml with NaCl 28 mmol/l and 58, iohexol only. ECG changes after contrast injections were evaluated with continuous computerized dynamic vectorcardiography (VCG). QRS-vector difference (QRS-vd), which reflects changes in the QRS-complex, was chosen as the main parameter. Both contrast media caused changes in the QRS-complex, but there was no significant difference between the two. No serious arrhythmias were observed. Both contrast media were well tolerated. No beneficial effects from enriching iohexol with sodium were found. VCG was found to be a valuable tool in the study of contrast medium-induced ECG changes.

A patient with a T1-T2 disc herniation, operated on via the anterior approach, is presented. In a search of the literature we found 18 reported cases, all operated on by posterior or posterolateral approaches. The feasibility of the anterior discectomy in our case was established by preoperative magnetic resonance imaging of the upper thorax. We think that an anterior discectomy at the level of the upper thoracic spine can be easily performed in selected cases. The clinical picture of T1 root compression is described.

Methods: Twelve patients with advanced epithelial nonadenocarcinoma of the paranasal sinuses and nasal fossa were treated with three cycles of cisplatin (100 mg/m2, day 1) and 5-fluorouracil (1000 mg/m2/24 hours on days 1-5 by continuous infusion), followed by preoperative external radiation therapy of 48 Gy and limited surgery, clearing the paranasal sinuses and nasal fossa., Results: After chemotherapy, 11 of 12 patients were free of the previous symptoms of disease. Clinical response rates were different, however, with an overall response rate of approximately 70% with no complete responses. Histopathologic analysis of resected specimens showed no vital tumor in eight patients, minimal microscopic disease in three patients, and infiltrating tumor in one patient. Local control was achieved in 11 of 12 patients. Ten patients are alive with no evidence of disease (mean follow-up, 27 months). Surgical mutilation was avoided, with no functional or cosmetic loss., Conclusions: The results of this small pilot study seem to indicate a high chemosensitivity of carcinomas of the paranasal sinuses and nasal fossa, which, in this study, has meant significant relief of symptoms and an unusually high rate of local control (90%) without mutilation.

Thirteen patients with normal pressure hydrocephalus were operated upon with an externally maneuverable shunt system (Sophy SU8) in order to investigate its influence on clinical outcome, intracranial pressure and cranial CT parameters. The opening pressure was set at high at surgery and lowered stepwise at intervals of three months to medium and low. The clinical condition, intracranial pressure and cranial CT parameters were examined at the end of the 3 months interval on each pressure level. The patients improved within the first 3 months inspite of an unchanged mean intracranial pressure and remained in a stable clinical condition during the rest of the study period. The intracranial pressure was significantly reduced at 9 months. The ventricular index, Evans index, temporal horn and third ventricle width were reduced 3 months post-operatively and did not change significantly during the rest of the study. The pre-operative third ventricle width was correlated to high psychometric test results after shunt surgery. Reduction in ventricular index, Evans index and third ventricle width after surgery correlated to improvement in psychometric scoring. The clinical improvement after shunt surgery for normal pressure hydrocephalus is seen within 3 months and is independent of the adjusted valve pressure.

Surgery was performed in the maxillary sinus with restoration of the surgical defect in the anterior wall with a resutured bone-lid, in 12 patients with an average age of 45 years, the technique is described and evaluated clinically and radiographically (computed tomography). During the followup time of 1-4 years, the condition of the maxillary sinus was normalized. It is our opinion that the bone-lid technique for maxillary sinus surgery is useful, especially when good overview and access is necessary.

The clinical value in neuropediatrics of [99mTc]HM-PAO brain single photon emission computed tomography was preliminary evaluated by the consecutive investigation of 79 children. Planned epilepsy surgery was the most common indication for the investigation. In 56 children investigated because of epilepsy, SPECT yielded relevant information in 79% of cases examined. The corresponding figures for magnetic resonance imaging and CT were 49% of 35 and 36% of 56 cases, respectively. All 22 children with an epileptic focus, ascertained by freedom from seizures after removal of the area or by consistent neurophysiological and neuroradiological findings, also had abnormal perfusion in the relevant area. Twenty-three children were examined because of neurological signs and symptoms other than epilepsy. SPECT findings were useful for elucidating neonatal brain impairments. Hypoperfused areas in the brain of asphyxiated infants and in posthemorrhagic hydrocephalus corresponded to neuroradiological and autopsy findings. SPECT was found to be an excellent tool when analysing cerebrovascular accidents. In cases with signs and symptoms of a diffuse severe encephalopathy, SPECT did not clarify the etiology but provided information on the distribution of the lesions and probable underlying pathophysiological mechanisms.

Cardiovascular effects have been attributed to the amino acids which are precursors of catecholamines or other neurotransmitters. To study if even other amino acids may exert cardiovascular or ventilatory effects, a number of various acidic, basic and neutral L-amino acids were injected intravenously to anaesthetised normotensive rats at the doses of 0.2-1.6 mmol/kg. All amino acids were able to produce either blood pressure, heart rate or ventilation rate changes. Hence, in this study the production of cardiovascular or ventilatory effects was not limited to the known precursors of neurotransmitters. Therefore, in addition to increased formation and release of neurotransmitters, other mechanisms are apparently involved in the cardiovascular and ventilatory effects of various L-amino acids.

Tyrosine exerts potent cardiovascular effects: smaller doses induce tachycardia and hypertension while higher doses induce bradycardia and hypotension. However, the direct cardiac effects of this amino acid have not been characterised. In the present study increasing doses of L-tyrosine were administered to the perfusate of isolated rat (0.01-10.0 mg) and rabbit (0.5-40.0 mg) hearts. Heart rate and isometric force of contraction or amplitude of contractions, and either perfusion pressure or flow of perfusate were recorded. In rat hearts L-tyrosine decreased heart rate and isometric force of contraction. In rabbit hearts L-tyrosine also decreased heart rate and amplitude of contractions. The effects on coronary vasculature were variable. In rat hearts, high doses of L-tyrosine induced bi-phasic changes with initial coronary dilatation, followed by vasoconstriction. In rabbit hearts the predominant effect of L-tyrosine was coronary artery constriction. These results show that the inhibitory cardiovascular effects of L-tyrosine in vivo may be at least in part, explained by direct cardiac effects of this amino acid.

Patients with a previous history of anaphylactic reactions to ionic iodinated contrast media were desensitised before a second radiologic examination was performed. The tolerance to the contrast medium was raised by repeated intravenous injections in increasing doses and concentrations. No serious side effects were noted when the examinations with contrast medium was repeated within a few days after the desensitisation. The positive effect of the desensitisation may depend on a successive consumption of complement proteins, probably responsible for the allergic reactions. Therefore, the available amount of complement for some days may be too low for the occurrence of a complement reaction.

Tyrosine is the precursor amino acid of catecholamines. Low doses of tyrosine produce tachycardia and hypertension, while higher doses induce bradycardia and hypotension in anaesthetised rats. The mechanism and site of action of L-tyrosine are not fully understood. Eight groups of Wistar rats received different pretreatments in order to study the influence of blockade of various receptor mechanisms on the cardiovascular effects of L-tyrosine. The effects mediated by the autonomic nervous system were inhibited by ganglion blockade (hexamethonium), by alpha 1- and beta 1-adrenoceptor blockade (prazosin and atenolol) and by parasympathetic acetylcholine receptor blockade (atropine). The possible role of histamine receptors was studied by inducing H1 and H2-receptor blockade (diphenhydramine and cimetidine, respectively). The effect of inhibition of prostaglandin synthesis by indomethacin was also studied. The L-tyrosine-induced tachycardia was completely blocked by atenolol. Both atenolol and prazosin partly inhibited the hypertensive effects of low doses of tyrosine. The tyrosine-induced bradycardia was not inhibited, and the hypotension was only partly blocked by the pretreatments. Therefore, adrenergic mechanisms seem to mediate the stimulatory cardiovascular effects of tyrosine. The depressant effects of high doses of tyrosine do not appear to be mediated by cholinergic activation, histamine receptor activation, or prostaglandin synthesis.

CT was used to document temporal lobe atrophy in 39 patients who were diagnosed clinically as having Alzheimer disease; the results were compared with those from 29 healthy elderly control subjects who were matched for age and education. The diagnosis of Alzheimer disease was made according to clinical criteria consistent with those specified by an NINCDS workshop. These included detailed medical and neuropsychological assessments. Temporal lobe atrophy was assessed by evaluating the temporal horns and sylvian cisterns. Temporal horn measurements greater than 3 mm occurred only in patients with Alzheimer disease while measurements less than or equal to this occurred in both Alzheimer patients and control subjects. Subjective evaluation of the sylvian cistern indicated that 24/29 controls had normal-appearing cisterns while only 5/39 Alzheimer patients had similar findings. In contrast to temporal horns, sylvian cisterns were more sensitive but less specific as discriminators between Alzheimer patients and normal controls.

The need for repositioning of surface coils and patients in MR examinations of the cervical and thoracic spine prolongs examination time. A new receiver design is proposed which overcomes this problem. The device is composed of two actively decoupled receiver coils mounted on the frame of a Philadelphia collar. These coils may be used separately to image either the thoracic or cervical spine or together to produce larger field-of-view images of the combined region. Signal-to-noise ratios of the separate cervical and thoracic spine images are not degraded as a result of mounting the receivers together. The full cervical and thoracic region is shown to be imaged at a signal-to-noise ratio significantly higher than that afforded by the body coil. A retrospective review of our case load suggests that a time saving could be achieved in approximately 1/3 of spine examinations by using this coil.

Thirty-five patients with non-oat-cell primary bronchogenic carcinoma were studied with computed tomography (CT) and retrospectively analyzed to evaluate the usefulness of CT in the preoperative staging. All patients underwent mediastinoscopy, and those with a negative exploration were referred for thoracotomy. Computed tomography demonstrated lymph nodes in 31 patients, 17 of them having nodes larger than 1 cm. Malignant involvement of lymph nodes was present in only 2 of these 17 patients. However, nodal involvement was present in five of the patients with lymph nodes less than 1 cm in diameter. Nine out of 10 patients who proved unresectable at thoracotomy were correctly evaluated at CT. Five additional patients were incorrectly presumed to be unresectable. The use of CT for staging of primary lung tumors, therefore, needs further investigation.

In a retrospective study, films from radiologic examinations of 13 patients with primary adenocarcinoma of the small bowel were reviewed. All patients had a barium examination and in 5 cases angiography was also performed. The barium studies disclosed strictures with overhanging edges in 11 patients, in 4 of whom there was a pronounced prestenotic dilation. Angiographically the predominant findings were in all cases hypovascularity and displacement of vessels. In 4 patients there was also encasement. Neovascularity was present in 2 patients. One patient showed angiographic changes due to intussusception.

Fifteen patients with bronchial carcinoma were treated with infusions of 10 mg Mitomycin C (MMC) in the bronchial artery feeding the tumor. The treatment was repeated three times with 2-3 weeks interval between treatments. Half of the patients then received radiation to the tumor area and mediastinum. All tumors decreased in size, complete remission occurred in two and partial remission in five patients. Survival time, however, was not prolonged and esophageal complications occurred in several patients.

Forty-one patients treated for primary malignancies of the brain at the University of Rochester Cancer Center since 1970 were assessed for adverse effects of irradiation clinically, and by computerized tomography (CT) and magnetic resonance (MR) imaging. At diagnosis, patients ranged in age from 1-65 years (median 19 years) and the most common tumor (in 30) was astrocytoma. Radiation doses ranged from 45 to 81.3 Gy (median 56.8 Gy). White matter changes visible on MR were graded on a scale of 1-4, with grades 1-2 known to occur in some normal patients. Areas of increased signal intensity not associated with the tumor or surgery were visible in all patients (gr 1 = 37%, gr 2 = 32%, gr 3 = 17%, gr 4 = 15%) whereas only 35% had regions of abnormality (hypodensity) on CT. Sulci enlargement and ventricular abnormalities (asymmetry or dilatation) were present in approximately 50% of patients by each technique. Higher grade MR lesions were associated with radiation to large volumes and high doses. For the 36 patients treated with 1.5-2.0 Gy daily fractions, the mean radiation dose by grade was as follows: gr 1 = 55.1 Gy, gr 2 = 58.8 Gy, gr 3 = 60.0 Gy, gr 4 = 63.5 Gy. All 5 patients treated on a hyperfractionated schedule had gr 1-2 changes despite receiving greater than 70 Gy. Fifty percent of patients treated to the whole brain (+/- boost) had gr 3-4 changes, compared with 14% treated with local fields (peak dose regions similar in both groups). Among the children (less than or equal to 13 years), 20% had gr 3-4 changes compared with 56% of adults (excluding hyperfractionated patients). This finding may be due entirely or in part to the lower radiation doses used for children (mean 54.4 Gy vs. 63.7 Gy in adults). Clinical abnormalities attributable to irradiation included an impairment in mental functioning in 7 adults, and learning disabilities in 5 children. Five of these adults (71%) had gr 3-4 changes on MR as compared to gr 3-4 changes in 29% of the remaining adult group. Five patients developed seizure disorders. We conclude that adverse effects of brain irradiation are more sensitively imaged by MR than CT and that these abnormalities are associated with larger treatment volumes and either (or both) higher doses or older age. Conversely, some patients treated with high radiation doses have unremarkable changes on MR, and others have severe white matter changes which are not clinically expressed.(ABSTRACT TRUNCATED AT 400 WORDS)

The cardiovascular and ventilatory effects of centrally and peripherally administered melatonin were examined in both normotensive rats (NTR) and in spontaneously hypertensive rats (SHR). In the experiments on anaesthetised NTR melatonin was administered intravenously at doses of 1, 10, and 100 mumol/kg, or intracerebroventricularly at doses of 0.01, 0.1, 1, and 10 mumol/kg. In the experiments on conscious SHR melatonin was administered orally at doses of approximately 2 mg per animal per day, or intracerebroventricularly at doses of 0.01, 0.1, 1, and 10 mumol/kg. Melatonin did not produce any significant cardiovascular or ventilatory effects in any of the experiments.

It is now recognized that patients infected by the virus linked to the acquired immunodeficiency syndrome (AIDS) can develop dementia symptoms as the initial and sometimes only symptomatology for AIDS. This appears to be a syndrome whose origin is independent of secondary non-viral infection or malignancy. Magnetic resonance imaging (MRI) in three patients with well documented AIDS dementia revealed high signal periventricular white matter lesions. In one case, large lesions were not apparent on computed tomography and gross inspection of the fixed brain prior to autopsy. In two cases in which serial in vivo MR studies were obtained, there was a progressive increase in lesion volume over a short (several months) period of observation. Periventricular white matter lesions may be an early sign accompanying AIDS dementia, and the degree of changes correlated well with the clinical picture in our patients.

There are conflicting reports on the blood pressure effects of tyrosine. The aim of this study was to establish complete dose-response relationships and to compare the effects of various modes of administration of L-tyrosine in anaesthetised normotensive and spontaneously hypertensive rats. The intravenous injection of L-tyrosine, 0.2-0.4 mmol/kg, produced tachycardic and hypertensive effects in both species. The higher doses (0.8-1.6 mmol/kg) produced marked bradycardiac and hypotensive responses. Intracerebroventricular administration of L-tyrosine, 0.005-0.1 mmol/kg, had no statistically significant effects. Chronic dietary administration of L-tyrosine at the approximate daily doses of 0.7-55 mmol/kg was also without any significant effects. These results suggest that the controversies in the earlier studies could be due mainly to differences in doses and modes of administration. Our results also suggest that the cardiovascular effects of tyrosine are peripheral rather than central in origin although a central site of action cannot be excluded.

Tyrosine is the precursor of catecholamines. Small doses of tyrosine produce tachycardia and hypertension while higher doses produce bradycardia and hypotension in anaesthetised rats. The mechanism of these effects has not been established. An increased synthesis and release of catecholamines has been suggested to be the mechanism. Various pretreatments were given to anaesthetised Wistar rats to study the influence of a blockade of L-tyrosine metabolism and thus a blockade of catecholamine synthesis, on these cardiovascular effects: valine, which inhibits tyrosine uptake into brain, alpha-methyl-p-tyrosine, which blocks the rate-limiting enzyme, tyrosine hydroxylase, carbidopa and benserazide, which both inhibit dopa decarboxylase, and desipramine, which blocks catecholamine re-uptake. Benserazide and alpha-methyl-p-tyrosine partially blocked the stimulatory effects of tyrosine. None of the pretreatments were able to block effectively the inhibitory effects of L-tyrosine. Therefore, the metabolism of tyrosine to form catecholamines may be involved in the stimulatory but not in the inhibitory cardiovascular effects of L-tyrosine. Valine pretreatment did not antagonize the depressant effects of tyrosine. Since valine blocks the uptake of L-tyrosine into the brain, the depressant effects of L-tyrosine might be peripheral rather than central in origin.

Technical aspects on surface coil magnetic resonance imaging of the spine using a superconducting system with a field strength of 1.5 tesla are described. By using a flat surface coil instead of the body coil the image quality was markedly improved and the signal-to-noise ratio (S/N) was increased approximately 2.6 times. Small voxels resulted in low S/N. The best image quality was achieved with a slice thickness of 5 mm, a field of view of 20 to 24 cm and a matrix of 256 X 256. Interleaved slices provided superior image quality compared with contiguous slices at the expense of acquisition time. For sagittal images the phase encoding gradient should be in the cranio-caudal direction to minimize motion artifacts. To obtain T1 and T2 images of high quality, spin echo pulse sequences with TR 600/TE 20 ms and TR 2000/TE 40 to 80 ms are useful.

The value of radiography in patients with tumors of the small bowel was assessed retrospectively in 63 patients, who had been subjected to radiography, in a series of 118 patients treated for such tumors. Thirteen of 17 jejunal tumors (76%) and 19 of 46 ileal tumors (41%) were diagnosed preoperatively. Elective barium examination of the small bowel was performed in 36 patients, in whom the tumors were diagnosed in 18. When the small bowel examination was performed during obstruction, 7 of 21 tumors were diagnosed. With the barium examination, adenocarcinomas and carcinoid tumors were often diagnosed correctly. In 32 patients angiography was carried out, and the nature of the tumor was disclosed in 24 (75%).

The effect of fat suppression on orbital MR imaging was tested by using a derivative of the Dixon method called chopper fat suppression in eight normal volunteers and eight patients with normal conventional orbital MR studies. Chopper fat suppression requires no postacquisition image processing or increased scan time and can be applied through a wide range of T1 to T2 weighting. In normal orbits, fat suppression was found to be advantageous for imaging the lacrimal gland and the optic nerve. Using fat-suppressed T1- or intermediate-weighted sequences, 2000/30 (TR/TE), the optic nerve was recognized by its high signal intensity relative to adjacent CSF, dural sheath, and surrounding fat. The technique minimized loss of anatomic detail by reducing chemical shift misregistration artifact. Disadvantages included an overall lower orbital signal/noise ratio. When used in conjunction with a TR/TE combination carefully selected for both anatomic region of interest and suspected pathology, the fat-suppression technique has the potential for improving the visualization of orbital lesions.

Intra-arterial digital subtraction angiography (DSA) can produce coronary artery opacification with isotonic contrast media. In this study we have examined the importance of electrolyte composition in isotonic formulations on the incidence of fibrillation. Right coronary injections of media were made for 25 s in anesthetized dogs. Isotonic meglumine diatrizoate and iohexol produced fibrillation in more than 68% of the injections, while sodium diatrizoate, saline, meglumine/sodium ioxaglate and iohexol with added sodium diatrizoate never produced fibrillation. These animal studies demonstrate a significantly higher risk of fibrillation (p less than 0.005) with isotonic nonionic and ionic media not containing sodium ions.

A double blind investigation comparing meglumine-Na diatrizoate (290 mg I/ml) and iohexol (300 mg I/ml) showed that patients receiving iohexol experienced significantly less discomfort. Patients who received diatrizoate commonly showed transient episodes of hypertension while those who received iohexol either showed no changes or transient episodes of hypotension. No significant changes in heart rate were observed in either group.