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Background. With modern CT imaging a comprehensive overview of cerebral macro- and microcirculation can be obtained within minutes in acute ischemic stroke. This opens for patient stratification and individualized treatment.Methods. Four patients with acute ischemic stroke of different aetiologies and/or treatments were chosen for illustration of the comprehensive CT protocol and its value in subsequent treatment decisions. The patients were clinically evaluated according to the NIHSS-scale, examined with the comprehensive CT protocol including both CT angiography and CT perfusion, and followed up by MRI.Results. The comprehensive CT examination protocol increased the examination time but did not delay treatment initiation. In some cases CT angiography revealed the cause of stroke while CT perfusion located and graded the perfusion defect with reasonable accuracy, confirmed by follow-up MR-diffusion. In the presented cases findings of the comprehensive CT examination influenced the treatment strategy.Conclusions. The comprehensive CT examination is a fast and safe method allowing accurate diagnosis and making way for individualized treatment in acute ischemic stroke.

PURPOSE: To compare absolute cerebral blood flow (CBF) estimates obtained by model-free arterial spin labeling (ASL) and dynamic susceptibility contrast MRI (DSC-MRI), corrected for partial volume effects (PVEs). METHODS: CBF was measured using DSC-MRI and model-free ASL (quantitative signal targeting with alternating radiofrequency labeling of arterial regions) at 3 T in 15 subjects with brain tumor, and the two modalities were compared with regard to CBF estimates in normal gray matter (GM) and DSC-to-ASL CBF ratios in selected tumor regions. The DSC-MRI CBF maps were calculated using a global arterial input function (AIF) from the sylvian-fissure region, but, in order to minimize PVEs, the AIF time integral was rescaled by a venous output function time integral obtained from the sagittal sinus. RESULTS: In GM, the average DSC-MRI CBF estimate was 150+/-45 ml/(min 100 g) (mean+/-SD) while the corresponding ASL CBF was 44+/-10 ml/(min 100 g). The linear correlation between GM CBF estimates obtained by DSC-MRI and ASL was r=.89, and observed DSC-to-ASL CBF ratios differed by less than 3% between GM and tumor regions. CONCLUSIONS: A satisfactory positive linear correlation between the CBF estimates obtained by model-free ASL and DSC-MRI was observed, and DSC-to-ASL CBF ratios showed no obvious tissue dependence. (Less)

The purpose of this prospective study was to compare 3T and 1.5T magnetic resonance angiography (MRA) with digital subtraction angiography (DSA) for the follow-up of endovascular treated intracranial aneurysms to assess the grade of occlusion.Thirty-seven patients with 41 aneurysms who had undergone endovascular treatment with detachable coils were included. MRA was performed on the same day using an eight-channel sensitivity encoding head-coil with 3D axial inflow technique. At 3T, a contrast-enhanced transverse 3D fast gradient echo acquisition was also performed. Most patients underwent DSA the following day. MRA scans and DSA were classified first independently by two neuroradiologists and an interventional neuroradiologist. Secondly, a consensus was done. Source images, maximum intensity projection, multiplanar reconstruction and volume rendering reconstructions were used for MRA evaluations. A modification of the Raymond classification, previously used for DSA evaluation of recanalization, was used.Statistical comparison of the consensus showed that 3T MRA with 3D axial inflow technique had better agreement with DSA (kappa = 0.43) than 1.5T MRA(kappa = 0.21) and contrast-enhanced MRA (CE-MRA) at 3T (kappa = 0.17). The susceptibility artefacts from the coil mesh were significally smaller at 3T (p = 0.002-0.007) than at 1.5T.3T MRA, using a sensitivity encoding head-coil, showed better agreement with DSA than 1.5T and CE-MRA at 3T for evaluation of aneurysms treated with endovascular coiling.

PURPOSE: To identify regional arterial input functions (AIFs) using factor analysis of dynamic studies (FADS) when quantification of perfusion is performed using model-free arterial spin labelling. MATERIAL AND METHODS: Five healthy volunteers and one patient were examined on a 3-T Philips unit using quantitative STAR labelling of arterial regions (QUASAR). Two sets of images were retrieved, one where the arterial signal had been crushed and another where it was retained. FADS was applied to the arterial signal curves to acquire the AIFs. Perfusion maps were obtained using block-circulant SVD deconvolution and regional AIFs obtained by FADS. In the volunteers, the ASL experiment was repeated within 24 h. The patient was also examined using dynamic susceptibility contrast MRI. RESULTS: In the healthy volunteers, CBF was 64+/-10 ml/[min 100 g] (mean+/-S.D.) in GM and 24+/-4 ml/[min 100 g] in WM, while the mean aBV was 0.94% in GM and 0.25% in WM. DISCUSSION: Good CBF image quality and reasonable quantitative CBF values were obtained using the combined QUASAR/FADS technique. We conclude that FADS may be a useful supplement in the evaluation of ASL data using QUASAR. (Less)

BACKGROUND: Patients with elevated intracranial pressure risk compromising their cerebral blood flow, resulting in ischemia. Lowering of the raised intracranial pressure, is therefore, mandatory. Reduction of the cerebral blood volume (CBV) might be target. In finding ways to do so, one has to be able to measure CBV. Measurement of CBV is, however, difficult. Radio(99mTc-)labeled erythrocytes (99mTcRBC) single photon emission computer-aided tomography (SPECT) is one established method used for CBV measurement. Recently, dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI), has also been successfully used for this purpose. The aim of this study was to validate the use of DSC-MRI for the measurement of CBV by the investigation of the correlation between the regional distributions of 99mTc-RBC SPECT and DSC-MRI measurement of CBV in humans. If possible, the aim was also to find a conversion constant that will enable the DCS-MRI to be interpreted as CBV (percent of brain volume). METHODS: CBV of 8 volunteers were studied under normocapnic and hypocapnic conditions. CBV was measured with both 99mTc-RBC SPECT and DSC-MRI. RESULTS: There were significant correlations between the regional distributions of CBV measured by 99mTc-RBC SPECT and DSC-MRI (rest: F=4.53, P

The rostral migratory stream (RMS) is the main pathway by which newly born subventricular zone cells reach the olfactory bulb (OB) in rodents. However, the RMS in the adult human brain has been elusive. We demonstrate the presence of a human RMS, which is unexpectedly organized around a lateral ventricular extension reaching the OB, and illustrate the neuroblasts in it. The RMS ensheathing the lateral olfactory ventricular extension, as seen by magnetic resonance imaging, cell-specific markers, and electron microscopy, contains progenitor cells with migratory characteristics and cells that incorporate 5-bromo-2′-deoxyuridine and become mature neurons in the OB.

Our purpose was to evaluate treatment safety as well as complications frequency and management in endovascular coiling of intracerebral aneurysms using MR diffusion and perfusion imaging. In this prospective study, 77 MR examinations were performed in conjunction with 43 procedures in 40 patients, 14 patients presented with ruptured and 26 with unruptured aneurysms. Mean time interval between treatment and post-procedure MRI was 29 and 25 h for the ruptured and unruptured aneurysm group, respectively. Peri-procedural complications, including five major events and five minor transient events, occurred in 10/43 procedures (23%), necessitating thrombolytic therapy in two patients and angioplasty in one, all three within the unruptured aneurysm group. Fifty-one new lesions were found on post-treatment DWI and 47 of them were regarded as of ischemic origin. Most lesions were small (

We have reviewed initial diagnostic features, treatment, and outcome in 29 patients with acute subarachnoid hemorrhage due to non-traumatic vertebrobasilar artery dissection diagnosed in our hospital between 1993 and 2003. The dissections occurred in the vertebral artery in 19 patients, the posterior inferior cerebellar artery (PICA) in two patients, the basilar artery in four patients, and in the vertebral artery extending into the PICA in four patients. A pseudoaneurysm was found in 20 patients. Clinical manifestations typically included sudden onset of moderate to severe headache, nuchal rigidity, and drowsiness. Fourteen patients were treated conservatively. Fifteen patients underwent endovascular treatment with either parent artery occlusion (13 patients) or aneurysmal coil occlusion with preservation of the parent artery (2 patients). Re-bleeding occurred within 12 days and before treatment in nine patients. Eight of these had a pseudoaneurysm. No patient bled after endovascular treatment. Poor grade and early re-bleeding were associated with less favorable outcome. Outcome at 6 months did not differ significantly between endovascular and conservative treatment. Altogether, good recovery was achieved for 16 patients, moderate disability was seen in one, severe disability in four, and eight patients (27%) died. The absence of bleeding subsequent to endovascular treatment in this study suggests that endovascular treatment may be a rational approach in these patients at high risk of re-bleeding, especially those with a pseudoaneurysm.

Hand-held vibrating tools may result in neuromuscular dysfunction and vasospastic problems of the hand. Sensory and motor dysfunction can be explained by injury to peripheral structures, but could also be due to changes in cortical somatotopic mapping of the hand in the brain. The purpose of the present study was to use functional magnetic resonance imaging (fMRI) to assess the somatotopic cortical representation of the hands of workers subjected to occupational vibration. The study included six men with severe vibration exposures who were suffering from hand–arm-vibration syndrome (HAVS) and six controls. The analysis focused on the pattern and degree of activation of contra- and ipsilateral hemispheres of the brain with tactile stimulation and motor activation of the hand. These stimulations resulted in well-defined activation of the contralateral, and to a lesser extent the ipsilateral hemisphere. Statistical analysis of this limited patient material did not indicate any significant somatotopic cortical changes following long-term exposure to vibrating hand-held tools, although there was a tendency to a shift of activation towards the more cranial parts of the cortex in the patient group.

Contrast enhanced magnetic resonance angiography (CE MRA) is a non-invasive alternative to conventional digital subtraction angiography (DSA). CE MRA is increasingly used as a complement to Duplex in the preoperative assessment of carotid artery stenosis. The purpose of this study was to determine if CE MRA could replace preoperative DSA. CE MRA with a scan time of 10 or 28 s was performed in 24 consecutive patients who were scheduled for preoperative DSA because of Duplex-verified severe carotid artery stenosis. Two neuroradiologists measured the degree of stenosis with three different methods, and the image quality was evaluated. DSA was used as the gold standard. For detection of severe stenosis (N. American symptomatic carotid endarterectomy trial (NASCET)or =70%; European symptomatic carotid endarterectomy trial (ECST)or =80%; common carotid artery method (CCAM)or =80%), the sensitivity of CE MRA maximum intensity projection (MIP) compared with DSA was 82%-100 %, the specificity was 74%-93% and the accuracy was 77%-90%. The inter-observer agreement was higher, the image quality was better and the intracranial main arteries were better visualized with the 28 s than with the 10 s scan time. The enhancement of the jugular veins seen in 17% of the 10 s scans and in 58% of the patients with the 28 s scans did not interfere with the evaluation of the carotid arteries. CE MRA, preferably with a scan time of 28 s, can replace DSA in the preoperative assessment of most patients with carotid artery stenosis.

In this study, EPI pulse sequences with diffusion weighting for reduction of contributions from large vessels and inversion pulses in order to minimize the effects of CSF pulsations and CSF partial volume effects were developed for BOLD contrast investigations in functional MR imaging. One inversion recovery echo-planar imaging (IR-EPI) pulse sequence and one IR-EPI with additional diffusion weighting (DW-IR-EPI) were developed and compared to a standard gradient-echo EPI sequence in a cortical stimulation experiment in nine healthy volunteers. Stimulation of motor cortex was performed using a semi-complex finger-tapping paradigm in seven periods of alternating rest and stimulation. Comparison between the three pulse sequences was made by measuring the activated volume in each subject, as well as by calculating the relative signal increase during stimulation. Due to different baseline signal-to-noise levels in the images generated by the three pulse sequences, artificial noise was added so that the comparative investigation could be performed independently of the noise level. The activated volume was 128 +/- 73 pixels (mean +/- SD) using the standard EPI pulse sequence, 31 +/- 12 pixels using IR-EPI and 15 +/- 13 pixels when DW-IR-EPI was employed. The relative signal increase was 5.7 +/- 1.1% using standard EPI, 11.5 +/- 3.1% using IR-EPI and 9.9 +/- 2.4% using DW-IR-EPI. The activated volume obtained with the addition of extra noise, i.e. at equal S/N, was 70 +/- 50 pixels using the standard EPI, and when using IR-EPI, the activated volume was 28 +/- 13 pixels. At equal S/N, the signal increase was 7.3 +/- 1.4% using standard EPI and 12.0 +/- 3.6% using IR-EPI. In BOLD contrast imaging, a combination of diffusion weighting and inversion recovery appeared to reduce false activation caused by CSF pulsation and blood flow in large vessels.

A magnetic resonance imaging (MRI) technique for the assessment of contractile and noncontractile components of human skeletal muscle is described, and the inter-rater and intra-rater test-retest reliability for repeated measurements from the same MR image are examined. Twenty cross-sectional MR images from the right lower leg were obtained from 30 healthy young men and women (mean age 24.1 years, SD 3.3). The anatomical cross-sectional area (aCSA; cm2), the cross-sectional area of noncontractile components (Noncon; cm2), the contractile cross-sectional area (cCSA = aCSA minus Noncon; cm2), and the relative amount of Noncon (%), of the ankle dorsiflexor muscle compartment were determined for each slice using a computer-based image analysis system. Reliability for repeated measurements of the slice with the largest aCSA for the 30 subjects was analyzed by two raters on two different occasions. Inter-rater reliability on both occasions, assessed by the intraclass correlation coefficient (ICC), was excellent for cCSA (ICC3.1 = 0.99) and Noncon (ICC(3.1)0.82). Intra-rater (between occasions) reliability was excellent for the two raters for measurements of cCSA (ICC1.1 = 0.99) and Noncon (ICC1.10.94). Bland and Altman analyses did not identify any clinically relevant bias in the measurements. Method errors were acceptable: within subjects coefficients of variation (CV) was less than 1.8% for cCSA and less than 16.3% for Noncon. It is concluded that repeated measurements of contractile and noncontractile components of the ankle dorsiflexor muscle compartment, obtained from the same MR image, are highly reliable.

In vivo magnetic resonance spectroscopy (MRS) addresses metabolic pathways and their steady states in different tissue types. The brain has by tradition, and due to technical limitations in other organs, been one of the tissues most studied by MRS, and both 1H- and 31P-MRS have been used. Although 31P-MRS is outstanding for the evaluation of sources of metabolic energy in the brain, 1H-MRS has become the major clinically applied method in neurospectroscopy, as it provides information on markers of neuronal function, myelin, cell membranes, and metabolic active compounds. Furthermore, MR sensitivity is much greater for protons than it is for phosphorus and 1H-MRS, therefore allowing better spatial resolution. This review focuses on neurospectroscopy and diagnostic insights into diverse neurological problems provided by 1H-MRS applied as a clinical tool.

Diffusion-weighted imaging (DWI) is very sensitive to early brain infarcts. However, the late stages have been insufficiently studied. Infarcts in small vessel disease are often multiple and of different ages, and differentiation between new and old lesions might be difficult. We have therefore studied the change with time in DWI of small (< 3 ml) ischaemic lesions. We imaged 21 patients with an acute lacunar syndrome and a lesion visible on early DWI. They all had three MRI examinations 12-58 h (early), 7-16 and 54-144 days after the onset of stroke; 10 patients with high DWI signal on the third examination had a fourth examination 12-28 months after the stroke. MRI was performed at 1.5 T, using echo-planar DWI with 7 b-values from 0 to 1200 x 10(6) s/m2 and conventional T2-weighted imaging. After 7-16 days 18 of 21 lesions gave high signal on DWI, and 12/16 measurable lesions had a decreased apparent diffusion coefficient (ADC). After 54-144 days ten lesions still gave high DWI signal and two still had an ADC below normal. On the fourth examination there was no remaining high DWI signal and all ADC were higher than normal.

Diffusion-weighted imaging (DWI) has been reported to be useful in the differential diagnosis between abscesses and cystic or necrotic tumours. However, experience is still limited and the true sensitivity and specificity remain to be determined. Our purpose is to describe a ring-enhancing metastasis of adenocarcinoma with a DWI pattern similar to that reported for abscesses. The tumour had a diameter of 1.5 cm and give signal from its centre similar to that of normal brain on T1-weighted images, whereas it was increased on T2-weighted images, and surrounded by a low signal ring, suggesting a capsule. The signal was high on DWI and the apparent diffusion coefficient (ADC) was low (0.55 x 10(-3) mm2/s). The findings were misinterpreted as representing an abscess in the early capsule-formation stage, but the signal pattern probably represented early tumour necrosis with intracellular oedema, but without liquefaction. Findings on DWI during the early capsule formation stage in abscesses and early tumour necrosis are probably similar and must be interpreted with caution.

To evaluate and compare the imaging findings and staging of rectal carcinoma by using conventional magnetic resonance (MR) imaging, MR imaging with an enema of superparamagnetic ferristene-based contrast material, and MR imaging with an enema of ferristene solution plus intravenous injection of gadodiamide.Twenty-nine patients (17 women, 12 men; age range, 39-91 years) referred with a diagnosis of rectal carcinoma were examined. Analysis of the rectal wall and staging of the tumor were performed. In all patients, the MR imaging findings were correlated with the histopathologic findings.The contrast material enema caused distention of the rectum and an intraluminal signal void, whereas the gadodiamide injection caused enhancement of the mucosa on T1-weighted images. This enhancement enabled evaluation of the normal rectal wall and differentiation of the mucosa, tunica muscularis, and perirectal space, which was not possible on the nonenhanced images. Double-contrast (ferristene solution plus gadodiamide) MR imaging was superior to imaging with only ferristene-based contrast material and had a sensitivity of 100%, specificity of 70%, and accuracy of 90% in distinguishing tumor stages worse than Dukes A.Double contrast material-enhanced MR imaging enables accurate rectal carcinoma staging, which is not possible at nonenhanced imaging.

OBJECTIVES: To evaluate if patients with acute lacunar syndromes have acute lacunar infarcts or other types of cerebral lesions on diffusion-weighted MRI. METHODS: Patients with acute lacunar syndromes underwent echo-planar diffusion MRI of the brain within 3 days after stroke onset. Localization and size of lesions with hyperintense signal were determined, compared with clinical characteristics and with findings on follow-up T2-weighted MRI. RESULTS: Twenty-three patients participated in the study. Thirteen patients had pure motor stroke, 1 pure sensory stroke, 8 sensorimotor stroke, and 1 ataxic hemiparesis. Twenty-two patients had at least one lesion with increased signal on diffusion-weighted MR images. These acute lesions were in the internal capsule/ basal ganglia/thalamus in 13 patients, subcortical white matter in 5 patients, brainstem in 2 patients, cortex (multiple small lesions) in 1 patient, and cortex + basal ganglia in 1 patient. The median volume of the lesions was 0.6 ml on the initial examination and on follow-up, of 17 patients after 1 to 5 months, 0.5 ml. CONCLUSIONS: Almost all patients with acute ischemic lacunar syndromes have acute lesions on echo-planar diffusion-weighted MRI within 3 days after stroke onset. These lesions are mostly small and subcortical, compatible with lacunar infarcts caused by single penetrating artery occlusion, but in a minor proportion of patients (2 of 23 in our study) a cortical involvement is found.

PURPOSE: To compare chemotherapy treatment monitoring in astrocytoma by 201thallium single photon emission computed tomography (SPECT) and photon magnetic resonance spectroscopy (1H-MRS) with magnetic resonance imaging (MRI), and to evaluate the influence of morphological tumor changes on cerebral 201thallium uptake and metabolic changes in 1H-MRS. MATERIALS AND METHODS: Six patients with highly malignant astrocytomas were followed with quantitative 201thallium SPECT, MRI, and 1H-MRS during chemotherapy. Maximum follow-up included six examinations per patient by either method during 18 months. Criteria were set for: (1) regression (> or = 25% tumor reduction), (2) status quo ( or = 25% tumor increase). Results were compared with the clinical state of disease. Changes of tumor volume, contrast enhancement, necrosis, hemorrhage and edema on MRI were compared to changes in 201thallium uptake volumes and 1H-MRS metabolite ratios. RESULTS: Six patients were followed with a total of twenty-four examinations with 201thallium SPECT, MRI and 1H-MRS, respectively, between February 1997 and October 1998. Five patients developed clinical progression of disease, 4 out of 5 cases showed SPECT progression, 4 out of 5 cases MRI progression, and 1 out of 2 interpretable cases 1H-MRS progression at final assessment before clinical deterioration. During the phase of clinically stable disease; (A) the criterion for regression or status quo was met in 10 out of 13 assessments with SPECT, 11 out of 13 with MRI, and 8 out of 9 interpretable 1H-MRS; (B) the criterion for progression was met in 3 out of 13 with SPECT, 2 out of 13 with MRI, and 1 out of 9 interpretable 1H-MRS. The accuracy of SPECT, MRI, and 1H-MRS in identifying changes of tumor burden concordant with patients' clinical course was 78%, 83%, and 82%, respectively. SPECT regression was associated with MRI decrease of tumor size, contrast enhancement, edema and hemorrhage. SPECT progression was associated with MRI increase of the same parameters and the increase of necrosis. 1H-MRS regression was associated with decrease of edema. 1H-MRS progression was associated with increase of tumor size, hemorrhage, and increase or decrease of contrast enhancement. CONCLUSIONS: Both 201thallium SPECT and 1H-MRS evaluation showed sensitivity for detection of astrocytoma progression. We did not find a higher accuracy of SPECT or MRS than of MRI in astrocytoma chemotherapy monitoring. Treatment induced MRI changes were associated with 201thallium uptake variations. 1H-MRS was difficult to apply for astrocytoma treatment monitoring. Improvements regarding size of measurement area such as multivoxel MRS and fat suppression pulses appeared desirable, and also the use of functional techniques with superior resolution such as dual isotope SPECT. However, our results suggest that 201thallium SPECT and 1H-MRS can provide additional information to MRI for chemotherapy efficacy evaluation in selected cases. (Less)

The greater sensitivity of magnetic resonance spectroscopy (MRS) compared with MRI to brain abnormalities in Rasmussen's encephalitis was demonstrated in a 3-year-old boy. The patient, with symptoms, signs and morphological findings consistent with Rasmussen's encephalitis, was followed with MRI and MRS over 30 months. That metabolic changes can be disclosed by MRS before the development of symptoms or signs was demonstrated as pathological spectra were found not only in the diseased left hemisphere but also in the morphologically normal right hemisphere before any neurological disturbance of that side.

In this work, a k-space segmentation technique for quantitative studies of pulsatile cerebrospinal fluid (CSF) flow is suggested. Three k-space lines are sampled for each of two interleaved gradient-echo sequences (velocity-compensated and velocity-encoded) within each repetition interval. Nine cardiac phases are obtained at a heart rate of 60 bpm with maintained nominal resolution and a factor of 3 in reduction of acquisition time relative to our conventional nonsegmented flow quantification protocol. Segmented and conventional sequences were compared in phantoms, in healthy volunteers, and in two patients with clinically suspected normal pressure hydrocephalus. Good agreement between flow curves obtained with the two sequences was demonstrated in vitro as well as in vivo. A slight underestimation of flow values in volunteers was attributed to data filtering when using the segmented sequence. Because the CSF circulation is complex and tightly connected to the vascular circulation, specific clinical applications may require flow studies at multiple positions and with different velocity encoding. In such cases, the proposed sequence can be used to gain time, but alternatively, the segmentation technique can be used to further increase spatial resolution within reasonable examination times.

Purpose: to describe the introduction and performance of proton MR spectroscopy (1H-MRS) in the daily routine of a modern standard MR unit Material and Methods: Over an 8-month period, 52 patients with brain lesions were studied with 1H-MRS, using SE and STEAM sequences for chemical-shift imaging and single-volume spectroscopy. the quality of the spectra was graded from 1 (best) to 3, and the main factors influencing the quality of the spectra were evaluated Results: of the measurements: 85% were graded as 1; 12% as 2; and 3% as 3. the main reasons for poor spectral quality were: the unfortunate positioning of the VOI; hemorrhage; and/or postoperative changes within the VOI. of 40 patients with a final diagnosis: MRS provided an increased confidence in MR diagnosis in 18 cases; MRS contributed significantly to preoperative diagnosis in 3 cases; and the spectra were not specific (n=10) or were difficult to evaluate (n=9) owing to reduced quality (grade 2 or 3) in 19 cases Conclusion: MRS of the brain can provide a high percentage of interpretable spectra and frequently can increase confidence in the MR diagnosis of brain lesions in clinical routine

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 μmol/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.

The fractional volume of capillary blood, i.e. the perfusion fraction f, was measured with the aid of an echo-planar imaging protocol originally designed for the measurement of water diffusion. in healthy volunteers, reasonable f values were obtained. in patients with cerebral ischaemic stroke, a marked decrease in the f value was seen in the infarcted region as compared with corresponding values in the contralateral hemisphere. We suggest that perfusion-fraction measurements may add to the diagnostic value of water-mobility examinations in patients with ischaemic disease

Purpose: To compare the diagnostic results following injection of (a) a high dose (0.3 mmol/kg b.w.) of gadodiamide injection and (b) the standard dose (0.1 mmol/kg b.w.) of Gd-DTPA, in patients with recurrent symptoms after surgery for lumbar disc herniation. Material and Methods: Twenty patients with recurrent or sustained symptoms after surgery for lumbar disc herniations were examined. MR imaging (0.3 T) was first performed before and after Gd-DTPA at 0.1 mmol/kg b.w., and then within one month (17 patients) or within 3 months (3 patients) before and after gadodiamide injection at 0.3 mmol/kg b.w. The examinations were first evaluated by 2 neuroradiologists blinded to dose but not to patient as the images were presented in pairs. Six months later the same investigators evaluated the examinations again, this time blinded to both dose and patient. Results: At the evaluation in pairs (with the investigators blinded to dose only) the high-dose examinations were considered the most informative (p=0.05). However, at the later evaluation (with the investigators blinded both to dose and patient) no significant difference between high and standard dose was found regarding diagnosis or diagnostic certainty. Conclusion: In this study the high-dose contrast enhancement of MR imaging at 0.3 T did not increase the diagnostic information for differentiating between scar and recurrent hernia. The high-dose images were considered more informative when evaluated in pairs, but gave no additional or different information when evaluated separately. The study also indicated that comparisons in pairs should be interpreted with caution.

PURPOSE: To evaluate radiologic findings and clinical data in patients with spontaneous spinal epidural hematoma (SSEH). MATERIALS AND METHODS: Thirteen patients (10 men aged 28-71 years; three women aged 40-65 years) with SSEH from 1986 to 1995 underwent magnetic resonance (MR) imaging; six also underwent spinal angiography. Patients with minor trauma, anticoagulant therapy, increased bleeding tendency, or vascular lesions were included. RESULTS: The incidence was estimated to be 0.1 patients per 100,000 patients per year. On MR images, the hematoma was in the anterior (n=8) or posterior (n=4) epidural space or both (n=1). The most common location was the upper thoracic region. T1-weighted images were most useful owing to the pathognomonic signal shift from isointensity with the cord in the early period to hyperintensity in the intermediate stage. Five patients had minor trauma, and four were receiving anticoagulant therapy. CONCLUSION: A rough estimation of the incidence of SSEH is provided,and the results confirm the previously described association with minor trauma and anticoagulant therapy and low frequency of arteriovenous malformations.

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.

Purpose: To evaluate the effects on cost, and number of primary and supplementary neuroradiologic examinations, after introducing MR imaging as the primary modality in the evaluation of the lumbar spine. Material and Methods: Two 5-month periods were compared: period 1 — before MR; and period 2 — after introduction of a 2nd MR device. In period 1, patients were examined with myelography and/or CT after referral from specialists only, whereas in period 2 both specialists and general practitioners could refer patients for MR imaging. The direct cost (neuroradiologic methods and hospitalization) and indirect cost (sick-leave and estimated loss of production caused by the diagnostic procedure) were estimated. Results and Conclusion: In period 1, investigations were started in 75 patients (62 myelographies and 13 CT examinations); in period 2, in 227 patients (198 MR, 21 CT, and 8 myelographies). The estimated total cost increased from SEK 825 000 to 1 265 000 (53%), the cost per investigated patient decreasing from 11 000 to 5565 (50%), and the cost of preoperative investigation per operated patient decreasing from 8616 to 5563 (35%). The number of supplementary examinations was unchanged.

Purpose and Material: The aim of this work was, firstly, to compare different manufacturer-provided MRA sequences in a 1.0 T MR unit, with respect to the visibility of an artificial stenosis in a flow phantom and, secondly, to evaluate the same sequences in healthy volunteers with respect to S/N ratio levels and practical in vivo implementation routines. Methods: The studied sequences were 2D and 3D TOF and sequences with an acquisition time of approximately 10 min. Quantitative signal evaluation was made using single transverse partitions in all phantom experiments. MIP angiograms and MPR reconstructions were made for visual inspection of image quality. In vivo, the images were individually evaluated by visual inspection by experienced neuroradiologists. Results: In the evaluation of the grade and length of a stenosis, a combination of MIP and MPR was seen to be the optimal and necessary procedure. A shortening of TE played an important and significant role in the visualization of the poststenotic flow in the phantom using TOF MRA. However, the shortest TE values gave poor S/N ratio in vivo. The good results achieved in the phantom studies for 3D phase-contrast were somewhat reversed in the volunteer studies, whereas 3D TOF sequences showed good results in both the phantom and the volunteer studies.

The aim of this study was to determine MRI findings in patients successfully operated upon for lumbar disc herniation. We investigated 20 patients with a successful outcome after L4-5 or L5-S1 disc operations clinically and with MRI preoperatively, and at 5 days, 6 weeks, and 4 months after surgery. Postoperatively, T1- and T2-weighted images were obtained. At 4 months gadolinium-enhanced images were added. Pronounced intraspinal MRI changes were seen during follow-up. Deformation of the dural sac was seen in 13 patients preoperatively, in 19 at 5 days after operation, in 15 at 6 weeks, and in 12 at 4 months. Nerve root involvement was seen in all cases both preoperatively and at 5 days after operation, in 17 at 6 weeks, and in 15 at 4 months. No correlation between symptoms or the straight leg raising test and the size or nature of the abnormal tissue in the spinal canal postoperatively could be demonstrated. It was concluded that early postoperative MRI after lumbar discectomy must be interpreted carefully, and that oedema and scar formation are probable reasons for difficulties in interpretation.

The aim was to compare the abilities of contrast-enhanced CT, non-contrast-enhanced MR imaging and contrast-enhanced MR imaging using standard (0.1 mmol/kg b.w.) and high (0.3 mmol/kg b.w.) doses of Gadodiamide injection to detect brain metastases (i.e. blood-brain barrier damage). Sixteen patients with at least 2 metastases found by CT were evaluated by MR imaging using non-contrast-enhanced spin-echo, T1-weighted, T2-weighted sequences, and contrast-enhanced spin-echo T1-weighted sequences at 2 dose levels. Gadodiamide injection was first given at the dose of 0.1 mmol/kg b.w. After imaging, another 0.2 mmol/kg b.w. was given, yielding a cumulative dose of 0.3 mmol/kg b.w. No contrast media-related adverse events were recorded. The images were evaluated openly by one and blindly by 2 investigators and the number of metastases, size, delineation (open study) and diagnostic certainty (blind study) of each individual metastasis noted. High-dose MR imaging showed significantly more and smaller metastases than any other examination, and gave a higher diagnostic certainty. All high-dose images were superior to those with the standard dose MR imaging when compared blindly in pairs. We conclude that spin-echo MR imaging with a high dose of Gadodiamide injection is an efficient way to improve the detection of brain metastases, in particular of small ones.

Background Computed tomography angiography (CTA) of intracranial arteries has high demands on image quality. Important parameters influencing vessel enhancement are injection rate, concentration of contrast media and tube voltage. Purpose To evaluate the impact of an increase of contrast media concentration from 300 to 400 mg iodine/mL (mgI/mL) and the effect of a decrease of tube voltage from 120 to 90 kVp on vessel attenuation and image quality in CT angiography of intracranial arteries. Material and Methods Sixty-three patients were included into three protocol groups: Group I, 300 mgI/mL 120 kVp; Group II, 400 mgI/mL 120 kVp; Group III, 400 mgI/mL 90 kVp. Hounsfield units (HU) were measured in the internal carotid artery (ICA) and the M1 and M2 segments of the middle cerebral artery. Image quality grading was performed regarding M1 and M2 segments, volume rendering and general image impression. Results The difference in mean HU in ICA concerning the effect of contrast media concentration was statistically significant ( P = 0.03) in favor of higher concentration. The difference in ICA enhancement due to the effect of tube voltage was statistically significant ( P < 0.01) in favor of lower tube voltage. The increase of contrast medium concentration raised the mean enhancement in ICA with 18% and the decrease of tube voltage raised the mean enhancement with 37%. Image quality grading showed a trend towards improved grading for higher contrast concentration and lower tube voltage. Statistically significant better grading was found for the combined effect of both measures except for general impression ( P 0.01–0.05). Conclusion The uses of highly concentrated contrast media and low tube voltage are easily performed measures to improve image quality in CTA of intracranial vessel.

Twenty patients with carcinoma of the pancreas identified with ultrasonography and/or CT and confirmed by histology, were examined with MR before and after administration of an oral superparamagnetic contrast medium. Ten patients were examined after administration of the contrast medium through a duodenal tube. Ten patients drank the contrast medium mixed with a viscosity-increasing agent. Organ delineation and diagnostic information were improved in the postcontrast scans in both groups and the viscous contrast suspension yielded better delineation and diagnostic information than the aqueous suspension. The viscous contrast suspension also showed better tolerance, contrast distribution and less artifacts than the aqueous suspension.

In five patients with clinical suspicion of spinal disease, MRI of the spine revealed unexpected aortic pathology explaining the symptoms. No significant intraspinal pathology was found on MRI. However, in one patient with clinical suspicion of spinal stenosis, an aortic occlusion was detected on MR images of the spine. The lower extremity ischaemia, caused by the occlusion, was responsible for the symptoms. In another patient a paravertebral haematoma from a ruptured aortic aneurysm resulted in spinal nerve compression, thought before MRI to be caused by a spinal tumour. In three patients aortic aneurysm or dissection resulted in spinal cord ischaemia with symptoms mimicking those of compressive spinal disease. Thus, if MRI of the spine does not provide an explanation for the patient's symptoms, examination of the aorta is recommended.

To improve image quality in a vertical field MR imaging unit, operating at low field strength (0.3 T), we have designed a half-elliptical coil for use in the upper thoracic region of small children. Our intention was also to shorten the examination time, which until now has been long, because several scans with different coils have been necessary to cover the thoracic region. The experimental coil is designed so that a child's shoulders fit into the central region. The coil consists of 2 serially connected cable-loops, mounted on a foam rubber vest. The coil performance was tested in a phantom and improvements relative to standard coils were demonstrated in in vivo studies. The results indicate that by using the half-elliptical coil, the signal-to-noise (S/N) ratio can be improved by a factor of 2 to 3 in the thoracic region of a child.

Ninety-one patients with extradural spinal tumours were examined by magnetic resonance imaging. There were 76 metastases (6 from unknown primary tumours). Seven patients had primary spinal tumours and 8 had multiple myeloma. Sixteen had bulging, diseased vertebral bodies compressing the subarachnoid space and 67 had extradural tumour compressing the spinal cord. Sixty patients had paravertebral involvement. Intraspinal involvement did not correlate with the extent of spinal lesions. All patients had vertebral destruction, with hypointense or combined hypo- and isointense signal relative to bone marrow on T1-weighted images. In most of the 22 patients with T2-weighted images the tumours were isointense or slightly hyperintense. It was usually impossible to differentiate the various tumours on the basis of signal intensity and morphology. However, metastases from carcinoma of the prostate were often more hypointense than other tumours on T1- and T2-weighted images. An inhomogeneous pattern in which diffusely low signal is combined with focal lower signal on T1-weighted images may suggest myeloma. In the 22 patients examined with both T1- and T2-weighted images, T1-weighted images gave the best information in 18; in 3 they were equivalent and in 1 inferior to T2-weighted images; they are therefore recommended for routine imaging of epidural spinal tumours.

The MRI examinations of seven patients with acute transverse myelopathy (ATM) were analysed. The patients were examined 2-5 times during the course of their disease with short and long TR/TE spin-echo sequences in the sagittal projection. A previous history of autoimmune disorder and/or signs of infection at the onset of ATM were present in all cases. Cerebrospinal fluid analysis showed local synthesis of immunoglobulin in the nervous system in three cases and signs of infectious myelitis in one. During the acute phase four patients had local enlargement of the cord and all had increased signal on long TR/TE sequences. The outcome was grave in the majority of patients and there seemed to be a correlation between the degree of cord enlargement, persistence of increased signal intensity and limited recovery. Atrophy and remaining high signal intensity were noted on late MRI in patients with poor outcome. In one patient with probable anterior spinal artery occlusion, cavitation of the cord was seen.

The differentiation between scar tissue and disk herniation is essential in postdiskectomy problems of the lumbar spine, since reoperation on scar tissue alone is often unfavourable. Epidural scar is a vascularized tissue, and enhancement can be seen after intravenous contrast injection, allowing differentiation from avascular disk material. Ten patients who had previously undergone surgery for lumbar disk herniation and with recurrent symptoms severe enought to warrant repeat surgery were examined by myelography, magnetic resonance imaging (MRI), and computed tomography (CT) before reoperation. MRI was performed with T1- and T2-weighted sequences in sagittal and axial projections before and after intravenous contrast injection. CT scans were obtained before and during intravenous contrast infusion. Reoperation revealed scar tissue, alone or together with disk, in 9 of 10 patients. Enhancement of scar but not of disk material was observed on MRI in 8 cases, but in none on CT. No enhancement of disk was seen with either modality. The correct diagnosis was given by MRI in 9 of 10 patients and by CT in 3 of 10. CT was superior to MRI in only 1 patient, who had a bony stenosis. Myelography could not separate disk from scar in any case. In conclusion, contrast-enhanced MRI was superior to MRI without contrast, CT before and after contrast, as well as myelography in discriminating disk from scar tissue.

Fourteen patients with spinal lymphoma examined by MR imaging were reviewed. Thirteen of them also had extraspinal lymphoma. Vertebral involvement was found in 12 patients, epidural in 10, and paraspinal in 8 patients. On the basis of MR imaging at 0.3 T, spinal lymphoma may be divided into three types of growth pattern according to the main location: paraspinal, vertebral, and epidural. Most frequently, all three locations were found simultaneously on MR (7/14). In one patient the location was vertebral with epidural extension, in one paraspinal with vertebral extension, in 3 it was entirely vertebral, and in 2 entirely epidural. Multiple plane T1-weighted imaging gave complete information about the extent of spinal lymphoma. The signal intensity was lower than or equal to muscle and lower than bone marrow in paraspinal and vertebral lesions on T1-weighted images and high on T2-weighted images. Epidural lesions showed a hypo- or isointense signal relative to the cord on T1-weighted images except in one case and a hyperintense signal on T2-weighted images. Compression of the cord and cauda equina due to bulging of diseased vertebral bodies and epidural lesions was well demonstrated. MR imaging was also found useful in the follow-up of treatment.

To improve image quality in the upper thoracic spine, an anatomically shaped copper wire loop coil, made to fit over the patient's shoulders, was constructed. The coil was permanently mounted on a foam-rubber vest to facilitate attachment to the patient. Phantom and in vivo studies of the performance of the coil in healthy volunteers showed as much as a two times greater signal-to-noise ratio relative to that of standard coils for the upper thoracic spine. In a patient with lesions in the upper thoracic cord, the coil gave better image quality in the region of interest than did the standard coils. The coil has been integrated into the authors' routine imaging equipment and has been the coil of choice for imaging of the upper thoracic spine on their 0.3-T vertical field system.

Thirty-one consecutive intradural extramedullary spinal tumors examined with MR at 0.3 T were reviewed. In 13 of the patients myelography had been performed. There were 11 patients with meningeoma, 14 with neuroma, one ependymoma, 3 metastases, and 2 lipomas. All tumors were surgically removed and verified by histology. The intradural extramedullary location of the tumors was accurately assessed by MR imaging in all patients and by myelography in 10 of 13. The MR diagnoses were in accordance with the histologic findings in 74% of cases. Compression of the spinal cord or cauda equina with widening of the subarachnoid space above and below the mass or outward displacement of epidural fat was characteristic of the intradural extramedullary tumors. The signal intensity of meningeoma as well as of neuroma was slightly lower or equal to that of the cord on T1-weighted images, and equal to or higher than cord signal on T2-weighted images. Neuroma had a lower signal intensity on T1-weighted images and a higher signal intensity on T2-weighted images than meningeoma. Meningeoma appeared more homogeneous than neuroma and had a broad base towards the dura.

Reduction of the cerebral perfusion pressure caused by vessel occlusion or stenosis is a cause of neurological symptoms and border-zone infarctions. The aim of this article is to describe perfusion patterns in hemodynamic stroke, to give a practical approach for the assessment of colour encoded CT- and MR-perfusion maps and to demonstrate the clinical use of comprehensive imaging in the workup of patients with hemodynamic stroke.Five patients with different duration cause and degree of hemodynamic stroke were selected. The patients shared the typical presentation with fluctuating and transient symptoms. All were examined by MR or CT angiography and MR or CT perfusion in the symptomatic phase. All patients were examined with diffusion weighted imaging. All five cases showed the altered perfusion patterns of hemodynamic insufficiency with a slight or marked increase in CBV in the supply area of the affected vessel and only slightly reduced or maintained CBF. The perfusion disturbances were most easily detected on the MTT maps. Border-zone infarctions were seen in all cases.The typical pattern for hemodynamic insufficiency is characterized by increased CBV, normal or decreased CBF and prolonged MTT in the affected areas. The increased CBV is the hallmark of stressed autoregulation. Reading the color-encoded perfusion maps enables a quick and robust assessment of the cerebral perfusion and its characteristic patterns. Internal border-zone infarctions can be regarded as a marker for hemodynamic insufficiency. Finding of the typical rosary-like pattern of DWI lesions should call for further work up.

Global cerebral perfusion parameters were measured using dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) in eight healthy volunteers examined during normal breathing and spontaneous hyperventilation. DSC-MRI-based cerebral blood flow (CBF) de- creased during hyperventilation in all volun- teers (average decrease 29%), and the corre- sponding global CBF estimates were 73±19ml/ (min100g) during normal breathing and 52± 7.9ml/(min100g) during hyperventilation (mean ±SD, n=8). Furthermore, the hypocapnic condi- tions induced by hyperventilation resulted in a prolongation of the global mean transit time (MTT) by on average 14%. The observed CBF estimates appeared to be systematically over- estimated, in accordance with previously pub- lished DSC-MRI results, but reduced to more reasonable levels when a previously retrieved calibration factor was applied.

To improve the reproducibility of arterial input function (AIF) registration and absolute cerebral blood flow (CBF) quantification in dynamic-susceptibility MRI-perfusion (MRP) at 1.5T, we rescaled the AIF by use of a venous output function (VOF). We compared CBF estimates of 20 healthy, elderly volunteers, obtained by computed tomography (CT)-perfusion (CTP) and MRP on two consecutive days. MRP, calculated without the AIF correction, did not result in any significant correlation with CTP. The rescaled MRP showed fair to moderate correlation with CTP for the central gray matter (GM) and the whole brain. Our results indicate that the method used for correction of partial volume effects (PVEs) improves MRP experiments by reducing AIF-introduced variance at 1.5T. Magn Reson Med, 2009. (Less)

The MR examinations in 25 patients with intramedullary tumors were analyzed. Seven patients were diagnosed with astrocytoma, 6 ependymoma, 2 unspecified glioma, 3 medulloblastoma, 2 metastasis, one neurinoma, and one teratoma. In 3 patients the diagnosis was uncertain. The tumors frequently involved a large portion of the cord and were often accompanied by intratumor necrosis, cystic degeneration, and edema, which was well demonstrated on MR. Gd-DTPA was used in 6 patients and was helpful in separating solid tumor components from cysts and edema. It was difficult to separate different kind of tumors based on morphologic and signal characteristics on MR. Some prominent features could, however, be distinguished. Complete cystic degeneration was more common in astrocytomas than in other tumors, and ependymomas frequently had a heterogeneous signal pattern on both T1- and T2-weighted sequences. The single teratoma had a characteristic content of fat and calcification, and the melanoma had a signal pattern consistent with blood. CSF pathway spread in cases of medulloblastoma was demonstrated by ill-defined contour of the cord and CSF or tumor nodules on the surface of cord and nerve roots.

The MR findings in 7 patients with neurofibromatosis involving the spine were evaluated. Six patients had paraspinal tumors at multiple levels. In 4 they were bilateral. Five patients had multiple intraspinal lesions, frequently with growth through the neural foramen. In one patient paraspinal tumors were found in the lumbar sacral plexus and in another bony dysplasia and meningoceles but no tumors were disclosed. In 2 patients the lesions were associated with bilateral acoustic neuromas and multiple intracranial meningeomas. In one of these a spinal meningeoma with signal characteristics close to spinal cord was found. The other tumors had a signal that was equal to or slightly lower than the spinal cord and slightly higher than muscle on T1-weighted images. On T2-weighted images the tumors had a markedly increased signal compared to surrounding tissue. In 3 patients with tumors larger than 4 cm the signal intensity was inhomogeneous with decreased signal in the center on T2-weighted images, indicating the presence of increased fibrous tissue. Gadolinium-DTPA was given to one patient with marked increase in intensity of small tumors on T1-weighted images. The study shows that MR imaging is the modality of choice for evaluating most aspects of spinal and paraspinal neurofibromatosis.

Seventeen patients with sciatica and isthmic lumbar spondylolisthesis were studied with magnetic resonance (MR) imaging. In 13, myelography was also performed: 5 had dural sac deformation and root sleeve shortening, 2 had deformation with unilateral root sleeve shortening, one had bilateral root sleeve shortening only, and one had sac deformation only. In 4, myelography was normal. On sagittal MR examinations the neural foramen had an altered shape bilaterally with the long axis horizontal in all cases. In addition to altered shape the following was found in the 33 foramina evaluated. I: normal nerve (n = 8); II: compressed nerve (n = 16); III: disappearance of fat, nerve not possible to identify (n = 9). In patients with unilateral sciatica, the degree of foraminal stenosis correlated well with the side of symptoms. Coronal views showed the course of the nerve and pedicular kinking. Eight patients underwent decompressive surgery which revealed nerve compression by hypertrophic fibrous tissue and pedicula...

This study presents 20 patients, randomised to receive either a collagen-treated or an ordinary Dacron graft for aortic reconstructions, and the results of a skin-prick test, blood parameters and ELISA for anti-collagen antibodies as well as NMR pictures during a 6 week follow-up period. Forty per cent (4/11) of those receiving a collagen impregnated graft had a significantly increased titre of antibodies and NMR revealed in two out of 11 patients either a slightly increased amount of fluid or fibrosis around the graft, both collagen impregnated. No differences were found between the graft groups concerning body temperature and leucocyte or platelet counts. The skin-prick test for collagen was negative in all cases.

Eighty-six patients with monosymptomatic optic neuritis of unknown cause were followed prospectively for a median period of 12.9 years. At onset, cerebrospinal fluid (CSF) pleocytosis was present in 46 patients (53%) but oligoclonal immunoglobulin in only 40 (47%) of the patients. The human leukocyte antigen (HLA)-DR2 was present in 45 (52%). Clinically definite multiple sclerosis (MS) was established in 33 patients. Actuarial analysis showed that the cumulative probability of developing MS within 15 years was 45%. Three risk factors were identified: low age and abnormal CSF at onset, and early recurrence of optic neuritis. Female gender, onset in the winter season, and the presence of HLA-DR2 antigen increased the risk for MS, but not significantly. Magnetic resonance imaging detected bilateral discrete white matter lesions, similar to those in MS, in 11 of 25 patients, 7 to 18 years after the isolated attack of optic neuritis. Nine were among the 13 with abnormal CSF and only 2 belonged to the group of 12 with normal CSF (p = 0.01). Normal CSF at the onset of optic neuritis conferred better prognosis but did not preclude the development of MS.