Optimizing the risk estimation after a transient ischaemic attack - the ABCDE⊕ score.

BACKGROUND AND PURPOSE: The risk of stroke after a transient ischaemic attack (TIA) can be predicted by scores incorporating age, blood pressure, clinical features, duration (ABCD-score), and diabetes (ABCD2-score). However, some patients have strokes despite a low predicted risk according to these scores. We designed the ABCDE+ score by adding the variables 'etiology' and ischaemic lesion visible on diffusion-weighted imaging (DWI) -'DWI-positivity'- to the ABCD-score. We hypothesized that this refinement increases the predictability of recurrent ischaemic events. METHODS: We performed a prospective cohort study amongst all consecutive TIA patients in a university hospital emergency department. Area under the computed receiver-operating curves (AUCs) were used to compare the predictive values of the scores with regard to the outcome stroke or recurrent TIA within 90 days. RESULTS: Amongst 248 patients, 33 (13.3%, 95%-CI 9.3-18.2%) had a stroke (n = 13) or a recurrent TIA (n = 20). Patients with recurrent ischaemic events more often had large-artery atherosclerosis as the cause for TIA (46% vs. 14%, P < 0.001) and positive DWI (61% vs. 35%; P = 0.01) compared with patients without recurrent events. Patients with and those without events did not differ with regard to age, clinical symptoms, duration, blood pressure, risk factors, and stroke preventive treatment. The comparison of AUCs [95%CI] showed superiority of the ABCDE+ score (0.67[0.55-0.75]) compared to the ABCD(2) -score (0.48[0.37-0.58]; P = 0.04) and a trend toward superiority compared to the ABCD-score (0.50[0.40-0.61]; P = 0.07). CONCLUSION: In TIA patients, the addition of the variables 'etiology' and 'DWI-positivity' to the ABCD-score seems to enhance the predictability of subsequent cerebral ischaemic events.

Significance of microbleeds in patients with transient ischaemic attack.

BACKGROUND AND PURPOSE: The aim of this study was to determine the prognostic significance of microbleeds in TIA-patients. In patients with a transient ischaemic attack (TIA), the prognostic value of microbleeds is unknown. METHODS: In 176 consecutive TIA patients, the number, size, and location of microbleeds with or without acute ischaemic lesions were assessed. We compared microbleed-positive and microbleed-negative patients with regard to the end-point stroke within 3 months. RESULTS: Four of the seven patients with subsequent stroke had microbleeds. Microbleed-positive patients had a higher risk for stroke [odds ratios (OR) 8.91, 95% CI 1.87-42.51, P<0.01] than those without microbleeds. Microbleed-positive patients with accompanying acute ischaemic lesions had a higher stroke risk than those with neither an acute ischaemia nor a microbleed (OR 6.20, 95% CI 1.10-35.12; P=0.04). CONCLUSION: Microbleeds alone or in combination with acute ischaemic lesions may increase the risk for subsequent ischaemic stroke after TIA within 3 months.

Fast high-resolution brain imaging with balanced SSFP: Interpretation of quantitative magnetization transfer towards simple MTR.

Magnetization transfer (MT) reflects the exchange of magnetization between protons bound to macromolecules, such as lipids and proteins, and protons in free liquid, and thus might be an early marker for subtle and undetermined pathologic changes in tissue. Detailed analysis of the entire MT phenomenon, however, commonly requires extensive data acquisition and scanning time, and hence is only of limited clinical interest. Therefore, in practice, magnetization transfer effects are commonly confined into a simple ratio measure, the so-called magnetization transfer ratio (MTR), calculated from a MT-weighted and a non-MT-weighted image. However, subtle physiologic and pathologic changes in tissue, invaluable for specific diagnostic imaging, may be lost since MTR-values depend not only on quantitative magnetization transfer (qMT) parameters but also on sequence parameters and relaxation properties. In order to evaluate and assess the diagnostic specificity of MTR versus qMT, high-resolution whole brain MT data was collected from twelve healthy volunteers using balanced steady-state free precession (bSSFP). In contrast to common MT imaging based on spoiled gradient echo (SPGR) sequences, whole brain qMT imaging can be performed with MT-sensitized bSSFP within a clinically feasible acquisition time. Hence, MT-sensitized bSSFP provides access to both MTR and qMT parameters within a clinical setting. The reliability and possible diagnostic value of MTR are analyzed for twelve white matter (WM) and eleven gray matter (GM) structures of the normal appearing brain. Strong correlations were found within and between longitudinal and transverse relaxation times (T1, T2) and MT parameters (ratio between macromolecular and water protons, F, and magnetization exchange rate, kf), whereas weaker correlations were observed between MTR-values and relaxation times or MT parameters. Structures with highly similar MTR-values, such as the crus cerebri and the anterior commissure in the WM, or the pallidum and the amygdala in the GM, however, were also found that showed significant differences in most quantitative parameters. This observation was confirmed from simulations revealing that the overall effect on MTR from an increase (decrease) in relaxation times may be counterbalanced with a decrease (increase) in MT parameters. These findings corroborate the expectation that qMT is superior to MTR imaging, especially for the evaluation and assessment of pathologic or physiological changes in healthy and pathologic brain tissue.

The pipeline embolization device for the intracranial treatment of aneurysms trial.

BACKGROUND AND PURPOSE: Endoluminal reconstruction with flow diverting devices represents a novel constructive technique for the treatment of cerebral aneurysms. We present the results of the first prospective multicenter trial of a flow-diverting construct for the treatment of intracranial aneurysms. MATERIALS AND METHODS: Patients with unruptured aneurysms that were wide-necked (> 4 mm), had unfavorable dome/neck ratios (<1.5), or had failed previous therapy were enrolled in the PITA trial between January and May 2007 at 4 (3 European and 1 South American) centers. Aneurysms were treated with the PED with or without adjunctive coil embolization. All patients underwent clinical evaluation at 30 and 180 days and conventional angiography 180 days after treatment. Angiographic results were adjudicated by an experienced neuroradiologist at a nonparticipating site. RESULTS: Thirty-one patients with 31 intracranial aneurysms (6 men; 42-76 years of age; average age, 54.6 years) were treated during the study period. Twenty-eight aneurysms arose from the ICA (5 cavernous, 15 parophthalmic, 4 superior hypophyseal, and 4 posterior communicating segments), 1 from the MCA, 1 from the vertebral artery, and 1 from the vertebrobasilar junction. Mean aneurysm size was 11.5 mm, and mean neck size was 5.8 mm. Twelve (38.7%) aneurysms had failed (or recurred after) a previous endovascular treatment. PED placement was technically successful in 30 of 31 patients (96.8%). Most aneurysms were treated with either 1 (n = 18) or 2 (n = 11) PEDs. Fifteen aneurysms (48.4%) were treated with a PED alone, while 16 were treated with both PED and embolization coils. Two patients experienced major periprocedural stroke. Follow-up angiography demonstrated complete aneurysm occlusion in 28 (93.3%) of the 30 patients who underwent angiographic follow-up. No significant in-construct stenosis (≥ 50%) was identified at follow-up angiography. CONCLUSIONS: Intracranial aneurysm treatment with the PED is technically feasible and can be achieved with a safety profile analogous to that reported for stent-supported coil embolization. PED treatment elicited a very high rate (93%) of complete angiographic occlusion at 6 months in a population of the most challenging anatomic subtypes of cerebral aneurysms.

Characterization of normal appearing brain structures using high-resolution quantitative magnetization transfer steady-state free precession imaging.

Compared to standard spoiled gradient echo (SPGR)-methods, balanced steady-state free precession (bSSFP) provides quantitative magnetization transfer (qMT) images with increased resolution and high signal-to-noise ratio (SNR) in clinically feasible acquisition times. The aim of this study was to acquire 3D high-resolution qMT-data to create standardized qMT-values of many single brain structures that might serve as a baseline for the future characterization of pathologies of the brain. QMT parameters, such as the fractional pool size (F), exchange rate (kf) and relaxation times of the free pool (T1, T2) were assessed in a total of 12 white matter (WM) and 11 grey matter (GM) structures in 12 healthy volunteers with MT-sensitized bSSFP. Our results were compared with qMT-data from previous studies obtained with SPGR-methods using MT-sensitizing preparation pulses with significantly lower resolution. In general, qMT-values were in good accordance with prior studies. As expected, higher F and kf and lower relaxation times were observed in WM as compared to GM structures. However, many significant differences were observed within WM and GM regions and also between different regions of the same structure like in the internal capsule where the posterior limb showed significant higher kf than the anterior limb. Significant differences for all parameters were observed between subjects. In contrast to previous studies, bSSFP allowed assessment of even small brain structures due to its high resolution. The observed differences from previous studies can partly be explained by the reduced partial volume effects. MT-sensitized bSSFP is an ideal candidate for qMT-analysis in the clinical routine as it provides high-resolution 3D qMT-data of even small brain structures in clinically feasible acquisition times. The present qMT-data can serve as a reference for the characterization of cerebral diseases.

Diffusion-weighted imaging findings differ between stroke attributable to spontaneous cervical artery dissection and patent foramen ovale.

BACKGROUND AND PURPOSE: Spontaneous cervical arterial dissection and patent foramen ovale (PFO) are important causes of stroke in younger patients. We tested whether characteristics of cerebral ischaemia visible on diffusion-weighted imaging (DWI) aid in differentiating between these two aetiologies. METHODS: Diffusion-weighted imaging was performed after a median of 2 days [interquartile range (IQR) 1-3 days] in 94 consecutive patients with an acute ischaemic stroke caused either by carotid or vertebral artery dissection (n = 33) or PFO (n = 61). We compared number, size, location and predefined patterns of DWI lesions between both aetiologies. RESULTS: Ninety-three out of 94 patients had acute DWI lesions and were included in the analysis. Multiple DWI lesions occurred more frequently in patients with dissection (23/33, 70%) than in those with PFO (26/60, 43%, P = 0.02). Lesions were larger in the dissection group [median diameter of largest lesion, 50 mm (IQR 19-68 mm)] than in the PFO group [23 (9-48) mm; P = 0.02]. The distribution of lesion patterns differed between the two aetiologies (P < 0.001): single, non-territorial infarcts were more frequent in PFO (25/60, 42%) than in dissection (2/33, 6%); large territorial infarcts with or without additional smaller lesions in the same territory occurred in 20/33 (61%) patients with dissection and in 16/60 (27%) patients with PFO. CONCLUSIONS: Diffusion-weighted imaging characteristics differ between PFO and dissection, suggesting differences in the pathogenesis of brain infarction between these aetiologies. A single non-territorial infarct seems to favour PFO as stroke aetiology. Whether this or other features are distinctive enough to diagnose PFO or dissection in individual patients requires further testing.

Cerebral venous thrombosis: diagnostic accuracy of combined, dynamic and static, contrast-enhanced 4D MR venography.

BACKGROUND AND PURPOSE: MR including MRV is an established method to diagnose CVT. However, it remains unsettled which MR imaging modalities offer the highest diagnostic accuracy. We evaluated the accuracy of a combined, dynamic (1.5 seconds per dataset) and static (voxel size, 1.1 x 0.9 x 1.5 mm), contrast-enhanced MRV method (combo-4D MRV) relative to other established MR/MRV modalities. MATERIALS AND METHODS: A total of 39 patients with CVT (n = 20) and control subjects (n = 19) underwent combo-4D MRV, 2D TOF MRV, GRE imaging, and T2W imaging. For these modalities, diagnostic accuracy (ROCs) for CVT affecting 53 out of 234 predefined venous segments was determined. Sensitivity and specificity were separately calculated for different stages of CVT (acute/subacute/chronic). RESULTS: Combo-4D MRV showed the highest accuracy (AUC, 0.99 [95% CI, 0.97-1.0]; sensitivity, 97% [84%-100%]) for thrombosed dural sinuses. For all thrombosed segments including cortical veins, its sensitivity was best (76% [64%-84%]; AUC, 0.92 [0.88-0.96]), followed by TOF MRV (72% [59%-81%]; AUC, 0.93 [0.88-0.97]). Even for chronic CVT, it showed a relatively high sensitivity of 67% (30%-90%). For thrombosed cortical veins alone, GRE images achieved the highest sensitivity (66% [46%-81%]; AUC, 0.88 [0.78-0.97]). Specificities of all modalities ranged from 96% to 99%. CONCLUSIONS: Combo-4D MRV showed an excellent accuracy for the diagnosis of dural sinus thrombosis. The analysis of dynamic patterns of contrast enhancement in dural sinuses appeared useful to identify chronic thrombosis. To diagnose thrombosed cortical veins, GRE images should primarily be analyzed.

MR angiography of dural arteriovenous fistulas: diagnosis and follow-up after treatment using a time-resolved 3D contrast-enhanced technique.

BACKGROUND AND PURPOSE: Digital subtraction angiography (DSA) is the method of reference for imaging of dural arteriovenous fistula (DAVF). The goal of this study was to analyze the value of different MR images including 3D contrast-enhanced MR angiography (MRA) with a high temporal resolution in diagnostic and follow-up imaging of DAVFs. MATERIALS AND METHODS: A total of 18 MR/MRA examinations from 14 patients with untreated (n=9) and/or treated (n=9) DAVFs were evaluated. Two observers assessed all MR and MRA investigations for signs indicating the presence of a DAVF, for fistula characteristics such as fistula grading, location of fistulous point, and fistula obliteration after treatment. All results were compared with DSA findings. RESULTS: On time-resolved 3D contrast-enhanced (TR 3D) MRA, the side and presence of all patent fistulas (n=13) were correctly indicated, and no false-positive findings were observed in occluded DAVFs (n=5). Grading of fistulas with this imaging technique was correct in 77% and 85% of patent fistulas for both readers, respectively. On T2-weighted images, signs indicative of a DAVF were encountered only in fistulas with cortical venous reflux (56%), whereas on 3D time-of-flight (TOF) MRA, most fistulas (88%) were correctly detected. In complete fistula occlusion, false-positive findings were encountered on both T2-weighted images and on TOF MRA images. CONCLUSION: In this study, TR 3D MRA proved reliable in detecting DAVFs and suitable for follow-up imaging. The technique allowed--within limitations--to grade DAVFs. Although 3D TOF MRA can depict signs of DAVFs, its value for follow-up imaging is limited.

Prominent activation of the putamen during essential palatal tremor: a functional MR imaging case study.

Palatal tremor (PT), also known as palatal myoclonus, is defined by short rhythmic contractions of the palatal musculature. Functional MR imaging (fMRI) revealed prominent bilateral neuronal activation in the putamen associated with essential palatal tremor (EPT) in a 41-year-old man. This implies a central role of the putamen in EPT, most likely as a consequence of diminished inhibition in an afferent pathway. Because fMRI primarily detects activations, dysfunctional areas remain obscure. The present functional study complements previous pathologic studies, which associated PT with lesions to dentate nucleus, red nucleus, and the inferior olive (Guillain-Mollaret triangle).

Percutaneous cervical vertebroplasty in a multifunctional image-guided therapy suite: hybrid lateral approach to C1 and C4 under CT and fluoroscopic guidance.

A 76-year-old patient suffering from two painful osteolytic metastases in C1 and C4 underwent percutaneous vertebroplasty by a hybrid technique in a multi-functional image-guided therapy suite (MIGTS). Two trocars were first placed into the respective bodies of C1 and C4 under fluoroscopic computed tomography guidance using a lateral approach. Thereafter, the patient was transferred on a moving table to the digital subtraction angiography unit in the same room for implant injection. Good pain relief was achieved by this minimally invasive procedure without complications. A hybrid approach for vertebroplasty in a MIGTS appears to be safe and feasible and might be indicated in selected cases for difficult accessible lesions.

Diffusion weighted imaging, apparent diffusion coefficient maps and stroke etiology.

OBJECTIVE: In acute ischemic stroke, the number and distribution of lesions on diffusion weighted imaging (DWI) have been shown to give clues to the underlying pathogenetic mechanisms. The objective of this study was to determine whether lesion features on DWI differ between stroke due to large artery atherosclerosis (LAA) and cardioembolism (CE), and to assess the role of apparent diffusion coefficient maps (ADC). METHODS: We retrospectively studied 83 consecutive patients with stroke caused by either LAA (n=40) or cardioembolism (n=43). DWI lesions were characterized by number, size, distribution (i. e. lesion pattern) and signal intensity on ADC maps. In part A, all hyperintense DWI lesions regardless of their ADC were compared. In part B, only hyperintense DWI lesions with hypointense appearance on ADC maps (i. e. acute lesions) were assessed. RESULTS: Part A: The frequency of multiple hyperintense DWI lesions (LAA: 28/40, CE: 21/43; p< 0.05) and the lesion number (LAA 4.7+/- 4.9; CE: 3.1+/- 4.7; p=0.01) were higher in LAA-patients. Involvement of >1 circulation (i. e. anterior plus posterior or bilateral anterior circulations) was present in 5 LAA-patients (13 %) and 4 CE-patients (9 %). Lesion size did not differ between LAA-stroke (35.1+/- 33.7 mm) and CE-stroke (35.4+/- 27.8 mm). Part B: Multiple hyperintense DWI lesions with low ADC occurred in 23/40 LAA-patients and in 15/43 CE-patients (p<0.05). Lesions in >1 circulation occurred only in CE-stroke (n=3; 7%) and never in LAA-stroke. CONCLUSIONS: (1) Multiple ischemic lesions occur significantly more often in LAA-stroke than in CE-stroke. (2) ADC maps are important in the comparison of DWI lesion patterns; DWI lesions in >1 circulation can only be assigned to a cardioembolic etiology if they appear hypointense on ADC maps.

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.

The clinical significance of diffusion-weighted MR imaging in infratentorial strokes.

OBJECTIVE: To study the association between diffusion-weighted imaging (DWI) characteristics and stroke etiology, stroke severity, and functional outcome in patients with infratentorial strokes. METHODS: The authors prospectively studied 22 consecutive patients with acute infratentorial strokes. They used a blinded comparison of DWI features (number, distribution, and volume of lesions) with clinical characteristics, namely, stroke etiology (Trial of ORG 10172 in Acute Stroke Treatment [TOAST] classification), severity (NIH Stroke Scale [NIHSS]), length of stay (LOS), and functional 3-month outcome using modified Rankin Scale, Barthel Index, and a dichotomized outcome status (living at home vs institutionalization or death). RESULTS: Acute infratentorial DWI lesions were detected in 95% (21/22) of the patients. The number (p = 0.01) and the distribution (p < 0.001) of DWI lesions were correlated with stroke etiology. Patients with cardioembolic strokes (n = 5) had more DWI lesions (8.0 +/- 6.0) than those with other stroke etiologies (n = 17; 1.3 +/- 0.9; p < 0.001). Their lesion distribution differed from that of patients with noncardioembolic strokes (p < 0.001). Clinically silent, acute DWI lesions in the anterior circulation in addition to their infratentorial lesions were visualized in 3 of 5 patients with cardioembolic stroke and in none of 17 patients without sources of cardioembolism (p < 0.001). Pure infratentorial lesions were present in 15 of 17 patients with noncardioembolic strokes and in none of 5 cardioembolic stroke patients (p < 0.001). DWI lesion volume was not correlated with NIHSS score, LOS, outcome scores, or outcome status. CONCLUSION: In infratentorial strokes, multiple DWI lesions and a distribution of subsidiary, clinically silent DWI lesions in the anterior circulation suggest a cardioembolic stroke etiology. However, DWI lesion volume did not correlate with the NIHSS score and was no predictor of outcome.

Diffusion-weighted MRI in cortical ischaemia.

We carried out MRI on 16 male and three female comatose patients, aged 2 days to 79 years, with suspected cortical ischaemia referred from our intensive care units. Using a head coil, and following standard imaging, including coronal fluid-attenuated inversion-recovery images, we performed diffusion-weighted imaging (DWI) using a whole-brain multislice single-shot echo-planar sequence with b 0 and 1000 s/mm2: 5-mm slices covering the whole brain, TR 7000 TE 106 ms, 128 x 128 pixels, field of view 250 mm, one excitation. Maps of apparent diffusion coefficients (ADC) were generated automatically. DWI showed cortical, basal ganglia and watershed-area high signal in all cases, associated with a decrease in ADC to 60- 80% of normal. DWI showed lesions not seen (40%) or underestimated (40%) on conventional T2-weighted imaging. Within 24 h of the onset of symptoms, DWI showed changes not readily detectable on T2-weighted images. The cortical high signal on DWI and the ADC changes, suggesting severe ischaemia rather than oedema, was found in areas known to be affected by cortical laminar necrosis. Extension to the brain stem and white matter was associated with a higher likelihood of death.

Swallowing abnormalities in multiple sclerosis: correlation between videofluoroscopy and subjective symptoms.

The purpose of this study was to evaluate if subjective symptoms indicating an impaired deglutition correlate with videofluoroscopic findings in patients with multiple sclerosis (MS). Videofluoroscopic examinations of 18 MS patients were analyzed by a radiologist and a logopedist and compared with the symptoms of these patients. Four patients complained about permanent dysphagia. Six patients reported mild and intermittent difficulties in swallowing, but were asymptomatic at the time of videofluoroscopy. Eight patients had no symptoms regarding their deglutition. All patients ( n=4) who complained of permanent dysphagia showed aspiration. All patients ( n=6) with mild and intermittent difficulties in swallowing showed undercoating of the epiglottis and/or laryngeal penetration. Of those 8 patients without any swallowing symptoms, only 2 had a normal videofluoroscopy. Swallowing abnormalities seem to be much more frequent in patients with MS than generally believed and they may easily be missed clinically as long as the patients do not aspirate.

Real-time interactive duplex MR measurements: application in neurovascular imaging.

OBJECTIVE: Real-time interactive duplex MR imaging is a new phase-contrast MR imaging technique that enables the quantification and display of flow velocities in real time without the need for cardiac gating. We investigated the feasibility and reliability of the technique to assess hemodynamic information both in vitro and in vivo in the carotid arteries and in the venous sinuses. SUBJECTS AND METHODS: Real-time interactive duplex MR measurements (TR/TE, 53/27; flip angle, 90 degrees; encoding velocity, 100 or 150 cm/sec) were performed in vitro with a steady-flow phantom and in 10 healthy volunteers in whom common and internal carotid artery velocities were measured. In eight volunteers, velocity measurements were also performed in the superior sagittal sinus during both normal breathing and hyperventilation. Time-velocity plots were analyzed qualitatively and quantitatively and compared with findings from conventional segmented k-space phase-contrast MR imaging and Doppler sonography. RESULTS: Velocity determinations for real-time duplex MR and conventional phase-contrast MR imaging showed an in vitro correlation of 0.99 and an in vivo correlation of 0.83 (carotid arteries) and 0.76 (venous sinus). Velocity measurements in the carotid arteries with real-time MR imaging were significantly lower than those obtained with conventional phase-contrast MR (averaged, 7.8%; p = 0.003) or sonography (23.7%, p < 0.001), likely because of volume averaging. Small but significant velocity changes occurring in the venous sinus during hyperventilation were reliably identified with both MR techniques. CONCLUSION: Real-time interactive duplex MR imaging can be effectively applied in neurovascular imaging to obtain hemodynamic information.