Single-hole, ruptured parenchymal arteriovenous fistula of the mesencephalon: not known vascular malformation of the brain or a posthemorrhagic entity?

The subtypes of brain arteriovenous malformations, with direct, single-hole fistulas without co-existing nidus are not described as existing entities inside the brain parenchyma but on the pial surface. True parenchymal arteriovenous malformations present with nidal structure, even if they are small, whereas surface lesions may present a direct fistulous configuration. In this case of midbrain haemorrhage a direct arteriovenous fistula was detected at the level of the red nucleus between a paramedian midbrain perforator artery and a paramedian parenchymal vein, with pseudo-aneurysm formation at the fistulous connection, without signs of adjacent nidus structure. The hypothesis whether a pre-existing arteriovenous fistula ruptured or a spontaneous haemorrhage has caused the fistulous connection is discussed.

How Flow Reduction Influences the Intracranial Aneurysm Occlusion: A Prospective 4D Phase-Contrast MRI Study

BACKGROUND AND PURPOSE

Flow-diverter stents are widely used for the treatment of wide-neck intracranial aneurysms. Various parameters may influence intracranial aneurysm thrombosis, including the flow reduction induced by flow-diverter stent implantation, which is assumed to play a leading role. However, its actual impact remains unclear due to the lack of detailed intra-aneurysmal flow measurements. This study aimed to clarify this relationship by quantitatively measuring the intra-aneurysmal flow using 4D phase-contrast MR imaging.

MATERIALS AND METHODS

We acquired prospective pre- and post-stent implantation 4D phase-contrast MR imaging data of a consecutive series of 23 patients treated with flow-diverter stents. Velocity field data were combined with the intraprocedural 3D angiogram vessel geometries for precise intracranial aneurysm extraction and partial volume correction. Intra-aneurysmal hemodynamic modifications were compared with occlusion outcomes at 6 and 12 months.

RESULTS

The averaged velocities at systole were lower after flow-diverter stent implantation for all patients and ranged from 21.7 ± 7.1 cm/s before to 7.2 ± 2.9 cm/s after stent placement. The velocity reduction was more important for the group of patients with aneurysm thrombosis at 6 months (68.8%) and decreased gradually from 66.2% to 55% for 12-month thrombosis and no thrombosis, respectively (P = .08).

CONCLUSIONS

We propose an innovative approach to measure intracranial flow changes after flow-diverter stent implantation. We identified a trend between flow reduction and thrombosis outcome that brings a new insight into current understanding of the flow-diversion treatment response.

Experimental evaluation of the NeVa™ thrombectomy device a novel stent retriever conceived to improve efficacy of organized clot removal

BACKGROUND AND PURPOSE

Stent retrievers are recognized as the most effective devices for intracranial thrombectomy. Although highly effective, such devices fail in clot removal when the brain vessel occlusion is due to organized, firm clots. The mechanism of failure is that during the retrieval, devices remain compressed by the organized clot and slide between it and the vessel wall without any removal effect. The aim of the current study is to present the preclinical evaluation of the Neva™ device, a novel stent retriever designed to improve the incorporation and removal of organized thrombi.

MATERIALS AND METHODS

Preclinical evaluation of the Neva™ device was divided in three main chapters: efficacy analysis, mechanical analysis and safety analysis. Efficacy and mechanical analysis aimed to investigate the behavior during the retrieval of the Neva™ device and its interaction with experimental organized clots. Safety analysis was conducted on animals in order to investigate the effect of the Neva™ device on real arteries after simulated thrombectomy maneuvers.

RESULTS

Neva™ device showed a high rate of "optimal clot integration" and "effective clot removal" which was related to constant cohesion to the vessel wall during retrievals. Safety analysis showed as the most frequent finding the disruption of the intima of the tested vessels with, in some cases, minimal disruption of the internal elastic lamina.

CONCLUSIONS

The Neva™ device has demonstrated safety and efficacy in a pre-clinical study. Such encouraging, preliminary results have to be compared with those of clinical trials.

Evaluation of electrode position in deep brain stimulation by image fusion (MRI and CT)

INTRODUCTION

Imaging has an essential role in the evaluation of correct positioning of electrodes implanted for deep brain stimulation (DBS). Although MRI offers superior anatomic visualization of target sites, there are safety concerns in patients with implanted material; imaging guidelines are inconsistent and vary. The fusion of postoperative CT with preoperative MRI images can be an alternative for the assessment of electrode positioning. The purpose of this study was to assess the accuracy of measurements realized on fused images (acquired without a stereotactic frame) using a manufacturer-provided software.

METHODS

Data from 23 Parkinson's disease patients who underwent bilateral electrode placement for subthalamic nucleus (STN) DBS were acquired. Preoperative high-resolution T2-weighted sequences at 3 T, and postoperative CT series were fused using a commercially available software. Electrode tip position was measured on the obtained images in three directions (in relation to the midline, the AC-PC line and an AC-PC line orthogonal, respectively) and assessed in relation to measures realized on postoperative 3D T1 images acquired at 1.5 T.

RESULTS

Mean differences between measures carried out on fused images and on postoperative MRI lay between 0.17 and 0.97 mm.

CONCLUSION

Fusion of CT and MRI images provides a safe and fast technique for postoperative assessment of electrode position in DBS.

Spinal cord ischemia: practical imaging tips, pearls, and pitfalls

Ischemia of the spinal cord is a rare entity with a poor prognosis. Brain ischemia is no longer a diagnostic challenge; on the contrary, ischemia of the spinal cord remains difficult, particularly in children. In this article, we illustrate the principal causes in children and adults, clinical presentation, different techniques for the diagnosis by MR imaging (diffusion, spinal MR angiography, and 1.5 versus 3T), pathophysiology, and differential diagnosis. We will discuss current knowledge, perspectives, and pitfalls.

Imaging of the cavernous sinus lesions

This educational paper reviews the normal anatomy of the cavernous sinus (CS) and the imaging findings of common and uncommon lesions of this region. CS lesions may arise from different components of the CS or from adjacent structures and spaces. They can be classified as tumoral, inflammatory/infectious, vascular and congenital. Tumoral lesions include benign (meningiomas, pituitary adenomas, schwannomas) and malignant neoplasms (chondrosarcomas, chordomas, nasopharyngeal carcinomas, leukemia, metastases). Inflammatory/infectious conditions comprise: Tolosa Hunt, abscess, Lemierre syndrome and thrombophlebitis. Vascular lesions include: hemangiomas, carotido-cavernous fistula, aneurysms, arteriovenous malformations. Congenital conditions include the epidermoid cyst, dermoid cyst and fatty deposits. Although imaging features of non-vascular CS diseases are most often non-specific, careful analysis of the adjacent structures suggests the correct diagnosis. In vascular pathology, characteristic MR imaging findings are observed.

Neuroimaging of diving-related decompression illness: current knowledge and perspectives

Diving-related decompression illness is classified into 2 main categories: arterial gas embolism and decompression sickness. The latter is further divided into types 1 and 2, depending on the clinical presentation. MR imaging is currently the most accurate neuroimaging technique available for the detection of brain and spinal cord lesions in neurologic type 2 decompression sickness. Rapid bubble formation in tissues and the bloodstream during ascent is the basic pathophysiologic mechanism in decompression illness. These bubbles can damage the central nervous system through different mechanisms, namely arterial occlusion, venous obstruction, or in situ toxicity. Neuroimaging studies of decompression sickness have reported findings associated with each of these mechanisms: some typical results are summarized and illustrated in this article. We also review the limitations of previous work and make practical methodologic suggestions for future neuroimaging studies.

[Radioinduced brain cyst: case report]

We present a case of intraparenchymal radioinduced cyst of the brain observed in our department. It is a rare and relatively benign pathology which is usually treated conservatively or by surgery. We emphasize long-term imaging follow up in patients treated by radiosurgery, which can lead to the demonstration of multiple adverse events such as tumefactive cyst formation.

Transvenous embolization of a ruptured deep cerebral arteriovenous malformation. A technical note

Ruptured cerebral arteriovenous malformations (AVMs) usually require treatment to avoid re-bleeding. Depending on the angioarchitecture and center strategy, the treatment can be surgical, endovascular, radiosurgical or combined methods. The classic endovascular approach is transarterial, but sometimes it is not always applicable. The transvenous approach has been described as an alternative for the endovascular treatment of small AVMs when arterial access or another therapeutic method is not possible. This approach can be considered when the nidus is small and if there is a single draining vein. We present a technical note on a transvenous approach for the treatment of a ruptured AVM in a young patient.

Flow-diverting stent for ruptured intracranial dissecting aneurysm of vertebral artery

BACKGROUND

The treatment of ruptured dissecting aneurysms of the intracranial vertebral artery (VA) with parent vessel preservation is a challenge for neurosurgeons and interventional neuroradiologists.

OBJECTIVE

To propose an indication for flow-diverting treatment for reconstruction of a dissecting VA with acute subarachnoid hemorrhage.

METHODS

Two male patients transferred after acute subarachnoid hemorrhage and dissecting aneurysm on the V4 segment of the dominant VA. An occlusion test was not performed because of their poor clinical state. A flow-diverting stent represented by the Pipeline embolization device was suggested to both patients.

RESULTS

Three Pipeline embolization devices were deployed in each VA. One dissecting aneurysm was excluded immediately after 3 stents, and 1 patient had complete exclusion demonstrated at the 48-hour control. No morbidity directly related to the procedure was observed. No recanalization and no rebleeding occurred during the 3 months of follow-up.

CONCLUSION

A flow-diverting stent may be considered an option to treat ruptured dissecting aneurysms of the VA, providing remodeling of the parent vessel and complete exclusion of the aneurysm.

Individual detection of patients with Parkinson disease using support vector machine analysis of diffusion tensor imaging data: initial results

BACKGROUND AND PURPOSE

Brain MR imaging is routinely performed in the work-up of suspected PD, yet its role is essentially limited to the exclusion of other pathologies. We performed a pattern-recognition analysis based on DTI data to detect subjects with PD at the individual level.

MATERIALS AND METHODS

We included 40 consecutive patients with Parkinsonism suggestive of PD who had DTI at 3T, brain (123)I ioflupane SPECT (DaTSCAN), and extensive neurologic testing including follow-up (17 PD: age range, 67.8 ± 6.7 years; 9 women; 23 Other: consisting of atypical forms of Parkinsonism; age range, 67.2 ± 9.7 years; 7 women). Data analysis included group-level TBSS and individual-level SVM classification.

RESULTS

At the group level, patients with PD versus Other had spatially consistent increase in FA and decrease in RD and MD in a bilateral network, predominantly in the right frontal white matter. At the individual level, SVM correctly classified patients with PD at the individual level with accuracies up to 97%.

CONCLUSIONS

Support vector machine-based pattern recognition of DTI data provides highly accurate detection of patients with PD among those with suspected PD at an individual level, which is potentially clinically applicable. Because most suspected subjects with PD undergo brain MR imaging, already existing MR imaging data may be reused; this practice is very cost-efficient.

Susceptibility-weighted MR imaging for diagnosis of capillary telangiectasia of the brain

BACKGROUND AND PURPOSE

BCT is a benign entity, whose appearance on conventional MR imaging makes its differentiation from neoplastic, inflammatory, or subacute ischemic disease challenging. SWI is sensitive to susceptibility effects from deoxyhemoglobin with excellent spatial resolution. Only scarce case reports have described the utility of SWI in cases of BCT. Our aim was to show the diagnostic value of SWI applied to a larger series of cases.

MATERIALS AND METHODS

This was an observational retrospective study of 33 BCTs in 27 consecutive patients examined from August 2009 to January 2011 with MR imaging, including SWI. Morphology, signal intensity characteristics, and additional vascular malformations were analyzed. Preceding or follow-up examinations were available in 18 patients with a median time interval of 14.5 months (range, 2-115 months).

RESULTS

Twenty-five pontine and 8 supratentorial BCTs demonstrated distinct signal-intensity loss on SWI in combination with postcontrast enhancement. Mean lesion diameter was 4.9 mm (range, 1.5-17 mm). Thirty-nine percent showed slight signal-intensity changes on T1 and/or T2; the remainder were isointense to normal brain. In 30%, a prominent draining vessel was observed. Additional cerebral vascular malformations were found in 5 patients.

CONCLUSIONS

SWI represents a valuable tool for confirmation of presumed BCT. Demonstration of signal-intensity loss on SWI in an enhancing focal brain lesion, otherwise unremarkable on conventional MR images, is highly specific for BCT, thus excluding serious pathology and reassuring the patient and referring physician. This is particularly helpful for BCT in less typical locations.

Combination of rare right arterial variation with anomalous origins of the vertebral artery, aberrant subclavian artery and persistent trigeminal artery. A case report

A 32-year-old woman hospitalized for subarachnoid hemorrhage showed rare arterial variation on the right side with anomalous origins of the vertebral artery, aberrant subclavian artery and persistent trigeminal artery. Angiography showed the right vertebral artery to originate from the right common carotid artery, the right subclavian artery to arise separately from the descending aorta, and persistent trigeminal artery on the right side. The possible embryonic mechanism of this previously unreported variant combination is discussed.

Clinical validation of an automated vessel-segmentation software of the extracranial-carotid arteries based on 3D-MRA: a prospective study

OBJECTIVES

To determine the accuracy of automated vessel-segmentation software for vessel-diameter measurements based on three-dimensional contrast-enhanced magnetic resonance angiography (3D-MRA).

METHOD

In 10 patients with high-grade carotid stenosis, automated measurements of both carotid arteries were obtained with 3D-MRA by two independent investigators and compared with manual measurements obtained by digital subtraction angiography (DSA) and 2D maximum-intensity projection (2D-MIP) based on MRA and duplex ultrasonography (US). In 42 patients undergoing carotid endarterectomy (CEA), intraoperative measurements (IOP) were compared with postoperative 3D-MRA and US.

RESULTS

Mean interoperator variability was 8% for measurements by DSA and 11% by 2D-MIP, but there was no interoperator variability with the automated 3D-MRA analysis. Good correlations were found between DSA (standard of reference), manual 2D-MIP (rP=0.6) and automated 3D-MRA (rP=0.8). Excellent correlations were found between IOP, 3D-MRA (rP=0.93) and US (rP=0.83).

CONCLUSION

Automated 3D-MRA-based vessel segmentation and quantification result in accurate measurements of extracerebral-vessel dimensions.

Efficacy and limitations of the neuroform stent system for intracranial aneurysms

SUMMARY

We performed aneurysm embolization in seven patients using a self-expandable Neuroform stent (Boston Scientific/Target, Fremont, CA) and coils to cover the aneurysm neck and fill the aneurysm sac. Seven patients with an average age of 45 were treated in the period from October 2002 to July 2003. The aneurysm lesions involved the basilar trunk in one case, the basilar-superior cerebellar artery in one case, the internal carotid artery in four cases, and the middle cerebral artery in one case. The ruptured lesions involved the internal carotid artery in one case and the middle cerebral artery in one case. We used a Neuroform stent measuring 4.5 x 20 mm in four cases, 4.5 x 15 mm in two cases, 3.5 x 20 mm in one case, and 3.5 x 15 mm in one case. We performed aneurysm coil embolization after Neuroform stenting in all cases without development of neurological deficits caused by the interventional procedure. In performing these procedures, we investigated the efficacy and limitations of the Neuroform stent system for intracranial aneurysms. The advantages of Neuroform self-expanding stents include better flexibility and adaptability to different vessel sizes, but this stent system presents various technical difficulties during delivery.

Method to quantify flow reduction in aneurysmal cavities of lateral wall aneurysms produced by stent implants used for flow diversion

SUMMARY

Stent implants placed across the neck of cerebral aneurysms are capable of reducing aneurysmal flow when coils are not used for filling the aneurysms. It is important to evaluate the effects of flow reduction caused by stent implants used for the treatment of cerebral aneurysms. Subtracted vortex centers path line method (SVC method) is one of the image post processing methods employed for quantitative flow measurement. We developed a modified SVC method by employing Cinematic Angiography (25 frames/s) and digital video recording (30 frames/s) with a commercial digital camera.We successfully compared the flow effectiveness using a tubular silicon model with a sidewall aneurysm. The result suggests that our modified SVC method is useful for a comparative examination of the effect of aneurysmal flow reduction caused by stent implants.

Early assessment of brain maturation by MR imaging segmentation in neonates and premature infants

PURPOSE

We evaluated the impact of premature extrauterine life on brain maturation.

PATIENTS AND METHODS

Twelve neonates underwent MR imaging at 40 (39.64 +/- 0.98) weeks (full term). Fifteen premature infants underwent 2 MR imaging examinations, after birth (preterm at birth) and at 40 weeks (41.03 +/- 1.33) (preterm at term). A 3D MR imaging technique was used to measure brain volumes compared with intracranial volume: total brain volume, cortical gray matter, myelinated white matter, unmyelinated white matter, basal ganglia (BG), and CSF.

RESULTS

The average absolute volume of intracranial volume (269.8 mL +/- 36.5), total brain volume (246.5 +/- 32.3), cortical gray matter (85.53 mL +/- 22.23), unmyelinated white matter (142.4 mL +/-14.98), and myelinated white matter (6.099 mL +/-1.82) for preterm at birth was significantly lower compared with that for the preterm at term: the average global volume of intracranial volume (431.7 +/- 69.98), total brain volume (391 +/- 66,1), cortical gray matter (179 mL +/- 41.54), unmyelinated white matter (185.3 mL +/- 30.8), and myelinated white matter (10.66 mL +/- 3.05). It was also lower compared with that of full-term infants: intracranial volume (427.4 mL +/- 53.84), total brain volume (394 +/- 49.22), cortical gray matter (181.4 +/- 29.27), unmyelinated white matter (183.4 +/- 27.37), and myelinated white matter (10.72 +/- 4.63). The relative volume of cortical gray matter (30.62 +/- 5.13) and of unmyelinated white matter (53.15 +/- 4.8) for preterm at birth was significantly different compared with the relative volume of cortical gray matter (41.05 +/- 5.44) and of unmyelinated white matter (43.22 +/- 5.11) for the preterm at term. Premature infants had similar brain tissue volumes at 40 weeks to full-term infants.

CONCLUSION

MR segmentation techniques demonstrate that cortical neonatal maturation in moderately premature infants at term and term-born infants was similar.

White matter lesions in watershed territories studied with MRI and parenchymography: a comparative study

Brain aging affects an increasing segment of the population and the role of chronic cerebrovascular disease is considered to be one of the main parameters involved. For this purpose we compared retrospectively MRI data with digitized subtraction angiography (DSA) data in a group of 50 patients focusing onto the watershed area of the carotid artery vascular territories. In order to evaluate the presence of white matter lesions (WML) in the hemispheric watershed areas, coronal fluid-attenuated inversion-recovery or axial T2 weighted MRI images of patients with symptomatic cerebrovascular insufficiency areas were compared with the capillary phase of DSA studies in anterior-posterior projection. Presence of cerebrovascular occlusive disease was evaluated on DSA using North American symptomatic carotid endarterectomy trial criteria and including evaluation of collateral vascular supply. Pathological MRI findings in the region of the watershed territories correlated overall in 66% of cases with a defect or delayed filling on DSA. In the case of asymmetrical MRI findings, there was a pathological finding of the capillary phase in the watershed area in 92% of DSA studies. Hypoperfusion in the capillary phase of the watershed area as seen on DSA correlated with the stenosis degree of the concerned carotid artery. Our findings suggest that asymmetrical findings of WML in the watershed areas as seen on MRI are caused by hemodynamic effect and a differentiation between small vessel disease and a consequence of distant stenosis may be possible under such conditions.

Double-lumen balloon microcatheter-assisted occlusion of cerebral vessels with coils: a technical note

The purpose of this study was to describe a balloon-assisted double-lumen microcatheter technique to perform a controlled and tight coil packing of a vascular segment for vessel occlusion. This technique can be performed immediately after a test occlusion with the balloon kept in place and was, as illustrated in six cases, in our experience safe, straight forward to use and fast.

Radiation dose in vertebroplasty

We wished to measure the absorbed radiation dose during fluoroscopically controlled vertebroplasty and to assess the possibility of deterministic radiation effects to the operator. The dose was measured in 11 consecutive procedures using thermoluminescent ring dosimeters on the hand of the operator and electronic dosimeters inside and outside of the operator's lead apron. We found doses of 0.022-3.256 mGy outside and 0.01-0.47 mGy inside the lead apron. Doses on the hand were higher, 0.5-8.5 mGy. This preliminary study indicates greater exposure to the operator's hands than expected from traditional apron measurements.

Multiresolution fuzzy clustering of functional MRI data

Recent developments in the analysis of functional MRI data reveal a shift from hypothesis-driven statistical tests to unsupervised strategies. One of the most promising approaches is the fuzzy clustering algorithm (FCA), whose potential to detect activation patterns has already been demonstrated. But the FCA suffers from three drawbacks: first the computational complexity, second the higher sensitivity to noise and third the dependence on the random initialization. With the multiresolution approach presented here, these weak points are significantly improved, as is demonstrated in our tests with simulated and real functional MRI data.

Acute leukoencephalopathy after inhalation of a single dose of heroin

We describe extended and repeat magnetic resonance (MR) examinations in the case of a 16-year-old male who developed acute left-sided sensorimotor hemiplegia after a single dose of inhaled heroin. MRI revealed symmetrical hyperintense signals in T 2 -weighted images and massive diffusion disorders in the diffusion weighted images predominantly in parieto-occipital subcortical white matter and both ventral globi pallidi with preservation of U fibers and no brain oedema. MR spectroscopy data were compatible with combined hypoxic and mitochondrial damage resulting in axonal injury without demyelination. Normal values and variations had been obtained from spectra of five age-matched subjects. This is the first reported MR follow-up study of leukoencephalopathy occurring acutely after a first inhaled dose of heroin. We postulate that toxic spongiform leukoencephalopathy in heroin addicts may be the outcome of a complex mechanism directly triggered by heroin and causing mitochondrial as well as hypoxic injury in specific and limited areas of white matter.

Diffusion weighted MR imaging on a low-field open magnet. Comparison with findings at 1.5T in 18 patients with cerebral ischemia

Diffusion-weighted MR imaging (DWI) is particularly sensitive for the detection of acute stoke. Until recently, DWI was performed with EPI technology. We compared 18 patients with clinical suspicion of acute stroke on a standard 1.5T unit and an open low-field MR scanner. Eighteen patients with 20 lesions of acute stroke were studied retrospectively with DWI and ADC mapping on both systems. The technique used was a rotating fast-spin echo T2 at low-field and an EPI sequence at 1.5T. Both examinations were performed within 24 hours and analyzed by two neuroradiologists. We obtained the same results on DWI sequences on both systems, regarding high intensity lesions on DWI. Interpretation of the ADC maps proved to be difficult on low-field MR near the lateral ventricles (3/18). We experienced the same difficulty of interpretation at low and high field in the cerebellum, in the temporal fossa and in cortex situated near bone, due to susceptibility artifacts. Chronic lesions were better visualized at low than at high field. In our opinion, DWI on a low-field open MR scanner is a good technique to evaluate subacute stroke and was as reliable as when performed on a 1.5T MR system.

Functional burst imaging

A quiet magnetic resonance (MR) imaging technique for detecting changes in cerebral activity functions is presented. This single-shot method, functional Burst imaging (FBI), combines elements of Burst imaging with an offset technique known as asymmetric spin echo (ASE). The FBI sequence has the unique feature of being nearly silent, because of the low number of gradient switching steps involved. Furthermore, this approach has the key advantage that it can be implemented on conventional MR systems. Established auditory and visual paradigms were used to evaluate whether FBI can detect changes in cerebral activity using a 1.5 Tesla MR system. In a second set of experiments, the FBI technique was used to evaluate cerebral activity changes during different sleep stages in humans. The results obtained demonstrate that the FBI sequence provides an alternative approach for functional imaging of brain activity in primary and secondary sensory areas of the human brain. Furthermore, in using this quiet MR technique, it was possible to scan continuously during different stages of human sleep without acoustic noise perturbation.

Line scan diffusion imaging: characterization in healthy subjects and stroke patients

OBJECTIVE

Our objective was to evaluate a new scanning method, MR line scan diffusion imaging, and assess the apparent diffusion coefficient in the brains of healthy subjects and stroke patients.

SUBJECTS AND METHODS

Line scan diffusion imaging without cardiac gating or head restraints was implemented on low- (0.5 T) and medium- (1.5 T) field-strength scanners with conventional hardware. Diffusion-weighted images were obtained in six healthy subjects and eight stroke patients. Unidirectional diffusion encoding was used for fast localization of stroke lesions. For further characterization, orthogonal diffusion encoding was applied, and the trace of the apparent diffusion coefficient was calculated. Single-shot diffusion-weighted echoplanar imaging served as the reference standard. For healthy subjects, imaging was repeated four times on each scanner. Mean and relative precision of the apparent diffusion coefficient trace values were calculated for each pixel. In stroke lesions and adjacent normal tissue, apparent diffusion coefficient trace values were determined.

RESULTS

In the 108 scans obtained, line scan diffusion imaging proved to be robust, virtually free of artifact (independent of slice location and orientation), reproducible, and rapid for localization of a stroke. Scan time for 14 slices at 7-mm thickness was 8 min at 0.5 T and 7 min at 1.5 T. Image qualities with line scan diffusion imaging and single-shot diffusion-weighted echoplanar imaging were comparable. At 1.5 T, precision was essentially the same for line scan diffusion imaging (4.3%) and echoplanar imaging (4.7%). With line scan diffusion imaging at 0.5 T and 1.5 T, normal paraventricular apparent diffusion coefficient trace values averaged 0.71 microm2/msec, and with echoplanar imaging these values averaged 0.69 microm2/msec. In acute lesions apparent diffusion coefficient trace values were low, and in chronic lesions these values were high.

CONCLUSION

Line scan diffusion imaging on low- and medium-field-strength MR scanners equipped with conventional hardware was reliable and practical for measuring brain apparent diffusion values, which can be applied to the early diagnosis, and hence timely management, of stroke.

Asymptomatic grotesque deformities of the cervical spine. An occupational hazard in railway porters

STUDY DESIGN

A case report.

OBJECTIVE

To illustrate an extremely rare occurrence of chronic, occupational, low-grade trauma leading to asymptomatic grotesque cervical spine deformities in railroad station porters.

SUMMARY OF BACKGROUND DATA

Occupational trauma causing spinal deformities has been described in relation to thoracic and lumbar spines in miners. To the authors' knowledge, this is the first reported case of asymptomatic cervical spinal deformity in railway porters as a result of chronic occupational trauma.

METHODS

A magnetic resonance imaging study was performed on both patients.

RESULTS

The magnetic resonance images showed advanced degenerative changes in the cervical spine causing obvious deformities, along with apparently normal cord signal intensity.

CONCLUSIONS

Chronic, occupational, low-grade trauma of the cervical vertebral region is extremely unusual in industrialized countries. Nevertheless, in view of the increasing mobility of people in general and of the labor force in particular, this complication of an occupational exposure deserves attention as an unusual cause of cervical spinal deformity.

Half-Fourier BURST imaging on a clinical scanner

A modified BURST imaging technique with a nearly twofold reduction in acquisition time, improved signal-to-noise ratio and clear improvement of the image quality is introduced. The method applies half-Fourier reconstruction and can be implemented on a standard clinical scanner. This approach allows the collection of single-shot magnetization prepared images of the human brain with a matrix size of 112 x 128 within 86-250 ms. The signal-to-noise properties of the pulse sequence are analyzed and compared with a standard BURST experiment.

Hypersomnia following paramedian thalamic stroke: a report of 12 patients

Paramedian thalamic stroke (PTS) is a cause of organic hypersomnia, which in the absence of systematic sleep-wake studies has been attributed to disruption of ascending activating impulses and considered a "dearoused" state. However, an increasing mount of data suggests a role of the thalamus in sleep regulation and raises the possibility that a sleep disturbance contributes to hypersomnia in PTS. We evaluated 12 patients with magnetic resonance imaging-proven isolated PTS and hypersomnia with 10 to >20 hours of sleep behavior per day. Nocturnal polysomnographic findings paralleled the severity of hypersomnia. All subjects had increased stage 1 NREM sleep, reduced stage 2 NREM sleep, and reduced numbers of sleep spindles. In patients with severe hypersomnia, slow-wave (stages 3-4) NREM sleep was often reduced, but there were no major REM sleep alterations. Daytime sleep behavior was associated mostly with stage 1 sleep by electroencephalogram; there was no correlation between hypersomnia and results of nap tests. We conclude that hypersomnia following PTS is accompanied by deficient arousal during the day and insufficient spindling and slow-wave sleep production at night. These observations support the hypothesis of a dual role of the paramedian thalamus as "final common pathway' for both maintenance of wakefulness and promotion of NREM sleep.