Computed diffusion-weighted imaging in patients with transient neurovascular symptoms with and without ischemic infarction

PURPOSE

Detection of ischemic lesions in patients with transient neurovascular symptoms is relevant for the estimation of the risk of a subsequent stroke and etiological classification. To improve detection rates, different technical approaches have been used, such as diffusion-weighted imaging (DWI) with high b-values or higher magnetic field strength. Here, we sought to investigate the value of computed DWI (cDWI) with high b-values in these patients.

METHODS

From an MRI report database we identified patients with transient neurovascular symptoms who underwent repeated MRI including DWI. cDWI was calculated with a monoexponential model with high b-values (2000, 3000, and 4000 s/mm2) and compared to the routinely used standard DWI with regard to presence of ischemic lesions and lesion detectability.

RESULT

Overall 33 patients with transient neurovascular symptoms (71 [IQR 57-83.5] years; 21 [63.6%] male) were included. On DWI, acute ischemic lesions were observed in 22 (78.6%). Acute ischemic lesions were observed in 17 (51.5%) patients on initial DWI, and in 26 (78.8%) patients on follow-up DWI. Lesion detectability was rated significantly better on cDWI at 2000s/mm2 compared to standard DWI. In 2 (9.1%) patients, cDWI at 2000s/mm2 revealed an acute ischemic lesion proven on follow-up standard DWI which was not detected with certainty on the initial standard DWI.

CONCLUSION

cDWI might be a valuable addition to routinely acquired standard DWI in patients with transient neurovascular symptoms since its use might result in improved ischemic lesion detection. A b-value of 2000s/mm2 seems most promising for clinical practice.

GLOS and HARM in patients with transient neurovascular symptoms with and without ischemic infarction

BACKGROUND AND PURPOSE

Gadolinium leakage in ocular structures (GLOS) on fluid attenuated inversion recovery images (FLAIR) is a novel imaging marker in acute ischemic stroke and other neurological disorders.

METHODS

In patients with transient neurovascular symptoms who underwent repeated MRI with intravenous contrast agent administration, the presence of acute ischemic lesions on diffusion-weighted images (DWI) as well as the frequency and pattern of blood-brain barrier and blood-retina barrier impairment as demonstrated by the hyperintense acute reperfusion marker (HARM) and GLOS respectively on postcontrast FLAIR were evaluated.

RESULTS

Overall 28 patients with transient neurovascular symptoms (median age 70.5 years; 18 (64.3%) male) were included. Follow-up MRI was performed within 35 (IQR 21-47) hours after the initial MRI. On DWI, acute ischemic lesions were observed in 22 (78.6%). On contrast-enhanced FLAIR, GLOS was observed in 12 (42.9%) patients: in 1 (3.6%) only in the anterior chamber, and in 11 (39.3%) in the anterior chamber and vitreous body. HARM was observed in 3 (10.7%) patients. In one patient without ischemic lesion on DWI or HARM on FLAIR, GLOS was observed in the anterior chamber and vitreous body. Presence of GLOS was associated with higher age (p = 0.04) and detection of HARM (p = 0.03).

CONCLUSIONS

In patients with transient neurovascular symptoms, GLOS is a frequent finding and associated with HARM on contrast-enhanced FLAIR. As GLOS was observed in one patient without an ischemic lesion or HARM, it might be useful as an additional imaging marker.

Deoxysphingolipid precursors indicate abnormal sphingolipid metabolism in individuals with primary and secondary disturbances of serine availability

Patients with primary serine biosynthetic defects manifest with intellectual disability, microcephaly, ichthyosis, seizures and peripheral neuropathy. The underlying pathogenesis of peripheral neuropathy in these patients has not been elucidated, but could be related to a decrease in the availability of certain classical sphingolipids, or to an increase in atypical sphingolipids. Here, we show that patients with primary serine deficiency have a statistically significant elevation in specific atypical sphingolipids, namely deoxydihydroceramides of 18-22 carbons in acyl length. We also show that patients with aberrant plasma serine and alanine levels secondary to mitochondrial disorders also display peripheral neuropathy along with similar elevations of atypical sphingolipids. We hypothesize that the etiology of peripheral neuropathy in patients with primary mitochondrial disorders is related to this elevation of deoxysphingolipids, in turn caused by increased availability of alanine and decreased availability of serine. These findings could have important therapeutic implications for the management of these patients.

Hippocampal infarction: Identification of three new types

BACKGROUND AND PURPOSE

Hippocampal infarction (HI) is common but yet still not comprehensively studied. In the present study, we aimed to identify novel HI patterns and to describe additional ischemic lesions outside the hippocampus to draw conclusions regarding the underlying vessel occlusion.

METHODS

In 222 patients (mean age 69.9 (±13.6) years; 129 (58.1%) male, 93 (41.9%) female) with HI, diffusion-weighted images were analyzed with emphasis on HI patterns and associated ischemic lesions outside the hippocampus. HI were classified as type 1 (complete), 2 (lateral), 3 (dorsal), and 4 (circumscribed). Further possible HI patterns were defined and classified as type 5 (ventral), 6 (ventrolateral), and 7 (dorsolateral).

RESULTS

Unilateral HI was found in 218 (98.2%) patients. In these, type 5 and 6 were identified in 5 (2.3%) patients, and type 7 in 8 (3.7%) patients respectively. Type 1 was found in 62 (28.4%), 2 in 53 (24.3%), 3 in 57 (26.1%), and 4 in 28 (12.8%) patients. Further ischemic lesions were found in the territory of the anterior cerebral artery (3.6%), middle cerebral artery (14.9%), anterior choroidal artery (AChA) (7.2%), posterior cerebral artery (89.6%), and in the brainstem (6.3%) and cerebellum (20.3%). Type 5 and 6 were significantly associated with acute ischemic lesions in the AChA territory (6/10 (60%) vs. 11/200 (5.5%), P<0.001).

CONCLUSIONS

We identified three novel HI types. Probably, type 5 and 6 can be attributed to occlusion of the AChA. Overall, these HI types are rare, possibly due to a better collateralization in the case of AChA occlusion.

Isolated punctuate hippocampal infarction and transient global amnesia are indistinguishable by means of MRI

Background Small punctuate lesions in the hippocampus on diffusion-weighted images are a typical finding in transient global amnesia. Consequently, it has been suggested that diffusion-weighted images findings might corroborate the diagnosis of transient global amnesia. However, isolated punctuate hippocampal infarction might be a differential diagnosis of transient global amnesia. Aim Evaluation of isolated punctuate hippocampal infarction frequency and comparison of its clinical presentation and MRI findings to transient global amnesia. Methods From an MRI database, we identified 10 patients with isolated punctuate hippocampal infarction and compared these to 12 patients with transient global amnesia with diffusion-weighted images lesion with regard to clinical symptoms and MRI findings. Results Disorientation and memory deficits were more common in transient global amnesia patients, whereas dysphasia/aphasia and vertigo were more common in hippocampal infarction patients. MRI findings in isolated punctuate hippocampal infarction and transient global amnesia did not differ significantly, neither regarding the affected hemisphere, lesion distribution, size, nor relative ADC values. Conclusions Differentiation of isolated punctuate hippocampal infarction and transient global amnesia based on neuroimaging findings is not possible. Thus, in the case of isolated punctuate hippocampal diffusion-weighted images lesions the final diagnosis of hippocampal infarction or transient global amnesia should be based on the clinical presentation.

IQWiG Arbeitspapier GA15-02: „Stents zur Behandlung intrakranieller Stenosen: VISSIT Studie und Akutbehandlung in Deutschland“

There is an ongoing discussion about reimbursement of stent-angioplasty for the treatment of intracranial stenoses in Germany. The discussion was initiated by the statutory health insurance companies after publication of the SAMMPRIS study results, which were in favor for medical management compared to stent-angioplasty with the Wingspan® stent system. A report (Rapid report N14-01) mainly based on SAMMPRIS was written by the German Institute for Quality and Efficiency in Health Care (IQWiG) and serves as a basis for the decision-making process. This report was previously commented by the medical societies involved. Limitations of the SAMMPRIS trial and vital indications for intracranial stenting were outlined in this comment (acute vessel occlusion, hemodynamic impairment, recurrent symptoms under medical treatment).Currently also emergency stent procedures are a matter of debate. In this context a second IQWiG report was commissioned (GA 15 - 02) addressing the results of the VISSIT trial, the transferability of the results of the first report to emergency treatments and the practice of emergency intracranial stent treatment in Germany6. Regarding transferability of results the main conclusion was that there was no evidence that the results of the studies analyzed for the first report (mainly SAMMPRIS) could not be transferred to emergency treatments. From a medical professional and scientific standpoint it is inacceptable to compare outcomes of a secondary prophylactic treatment with emergency procedures. The analysis of emergency treatments in Germany based on retrospective case series with a cumulative number of 31 patients. Since most emergency procedures are performed in a clinical context and are not necessarily subject to scientific evaluation, this does not reflect current practice in Germany.The first part of this statement briefly outlines the design of SAMMPRIS and VISSIT and the interpretation of the trial results from a professional perspective. The current state of discussion regarding reimbursement of intracranial stenting is summarized. The second section contains a detailed comment on the current IQWiG report GA15-02 "Stents for the treatment of intracranial artery stenosis: VISSIT study and acute treatment in Germany".

Patient characteristics support unfavorable psychiatric outcome after treatment of unruptured intracranial aneurysms

INTRODUCTION

Previous studies demonstrated an unfavorable psychological outcome after treatment of unruptured intracranial aneurysms despite an objectively favorable clinical and radiological outcome. The current study was therefore designed to analyze the psychiatric vulnerability of this specific patient collective.

MATERIALS AND METHODS

Patients treated for a WHO grade I meningioma and incidental intracranial aneurysms in two German neurosurgical centers between 2007 and 2013 were screened for exclusion criteria including malignant/chronic diseases, recurrence of the tumor/aneurysm after more than 12 months and focal neurological deficits, among others. Seventy-five meningioma patients (M) and 56 incidental aneurysm patients (iA) met the inclusion criteria. The past medical psychiatric history, post-morbid personality characters and coping strategies were determined by questionnaires mailed to the patients in a printed version (Brief COPE, Big Five Personality Test).

RESULTS

Fifty-eight M and 45 iA patients returned the questionnaires. Patients with iA demonstrated significantly higher pre-interventional rates of depressive episodes (p = 0.002) and psychological supervision (p = 0.038). These findings were especially aggravated in iA patients who received their cranial imaging for unspecific symptoms such as dizziness, headaches or tinnitus (n = 33, history of depressions: 39.4%; previous psychological supervision: 33.3%). Furthermore, the analysis of the Big Five personality traits revealed remarkably elevated neuroticism scores in the iA collective.

CONCLUSION

The current study demonstrates an increased rate of positive pre-interventional psychiatric histories in the iA collective. Although those patients represent only a small subgroup, they still may play an important role concerning the overall outcome after iA treatment. Early detection and psychological support in this subgroup might help to improve the overall outcome. Further studies are needed to evaluate the influence of this new aspect on the multifactorial etiology of unfavorable psychiatric outcome after treatment of iA.

In vivo X-ray digital subtraction and CT angiography of the murine cerebrovasculature using an intra-arterial route of contrast injection

BACKGROUND AND PURPOSE

Investigation of the anatomy, patency, and blood flow of arterial and venous vessels in small animal models of cerebral ischemia, venous thrombosis, or vasospasm is of major interest. However, due to their small caliber, in vivo examination of these vessels is technically challenging. Using micro-CT, we compared the feasibility of in vivo DSA and CTA of the murine cerebrovasculature using an intra-arterial route of contrast administration.

MATERIALS AND METHODS

The ECA was catheterized in 5 C57BL/6J mice. During intra-arterial injection of an iodized contrast agent (30 μL/1 sec), DSA of the intra- and extracranial vessels was performed in mice breathing room air and repeated in hypoxic/hypercapnic mice. Micro-CTA was performed within 20 seconds of intra-arterial contrast injection (220 μL/20 sec). Image quality of both methods was compared. Radiation dose measurements were performed with thermoluminescence dosimeters.

RESULTS

Both methods provided high-resolution images of the murine cerebrovasculature, with the smallest identifiable vessel calibers of ≤ 50 μm. Due to its high temporal resolution of 30 fps, DSA allowed identification of anastomoses between the ICA and ECA by detection of retrograde flow within the superficial temporal artery. Micro-CTA during intra-arterial contrast injection resulted in a reduced injection volume and a higher contrast-to-noise ratio (19.0 ± 1.0) compared with DSA (10.0 ± 1.8) or micro-CTA when using an intravenous injection route (1.3 ± 0.4).

CONCLUSIONS

DSA of the murine cerebrovasculature is feasible using micro-CT and allows precise and repeated measurements of the vessel caliber, and changes of the vessel caliber, while providing relevant information on blood flow in vivo.

Arterial spin labeling at 3.0 Tesla in subacute ischemia: comparison to dynamic susceptibility perfusion

PURPOSE

Arterial spin labeling (ASL) is a promising but clinically not established non-invasive method to assess cerebral perfusion. The purpose of this study was to compare perfusion imaging with pulsed ASL (pASL) to conventional dynamic susceptibility contrast (DSC) perfusion-weighted imaging (PWL) using commercially available equipment and postprocessing (3.0 Tesla, 32-channel head coil) in patients with subacute ischemia.

METHODS

The pASL and DSC-PWI techniques were compared in 15 patients with subacute ischemia (age 49-88 years, 6 females and 9 males, time from onset to scan 4-161 h). Image inhomogeneity was assessed with the non-uniformity index. Image quality, delineation of hypoperfusion and degree of hypoperfusion were rated by two readers using a 5-scale grading system. The volume of hypoperfusion was quantified planimetrically.

RESULTS

Image quality and image inhomogeneity were superior in DSC time-to-peak (TTP) compared to pASL cerebral brain flow (CBF; both p < 0.05). The delineation of hypoperfusion was better in DSC-TTP (p < 0.05) and the hypoperfusion was graded as more severe in DSC-TTP (p < 0.05). The volume of hypoperfusion did not differ between pASL-CBF and DSC-TTP, however, in pASL-CBF five cases with small infarctions (lacunar and pontine) were false negative compared to DSC-relative CBF. The mismatch frequency was lower in pASL (13%) than in DSC-rCBF (20%) and DSC-TTP (47%).

CONCLUSIONS

Using a commercially available sequence and a 32-channel head coil at 3.0 Tesla pASL-CBF is feasible but limited compared to DSC-PWI in the assessment of ischemic stroke. In its present form pASL has a reserve role in clinical practice for situations when gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) is contraindicated.

TrueFISP of the pediatric pineal gland: volumetric and microstructural analysis

PURPOSE

Although high-resolution 3D-imaging has markedly improved the imaging of the pediatric pineal gland, the prevalences of typical and atypical cysts as well as in vivo volumes are unknown. The purpose of this study was to compare the frequency of typical and atypical cysts using high-resolution 3D-sequence true fast imaging with steady state precession (trueFISP) and standard sequences and to directly measure the pineal volume in a large pediatric population.

METHODS

In 54 consecutively examined children (age 0-17 years, mean age 5.4 ± 5.6 years, 44% female, 56% male) the prevalence of typical and atypical cysts (thickened rim, trabeculations, asymmetry) was determined using trueFISP (isotropic, 0.8 mm) and standard sequences, 1.5-T, T1-weighted spin echo (T1-SE), T2-weighted turbo spin echo (T2-TSE) and fluid attenuated inversion recovery (FLAIR). Indistinct findings were noted separately. Volumetry was based on the trueFISP datasets. Solid and cystic compartments were approached separately. The pineal volume was correlated to gender and age.

RESULTS

The detected frequency of pineal cysts was higher in trueFISP (57.4%) than in standard sequences (T1-SE 7.4%, T2-TSE 14.8%, and FLAIR 13.0%). In trueFISP 66.3% of the detected cysts were classified as atypical (standard sequences 0%). Indistinct findings were lowest in trueFISP. The mean pineal volume was 94.3 ± 159.1 mm³ and no gender related differences were found. Age and volume showed a moderate correlation (r = 0.382) which was remarkably higher in completely solid glands (r = 0.659).

CONCLUSIONS

TrueFISP imaging improves the detection of pineal cysts in children. A typical cysts are frequently detected as an incidental finding. Volumetric analysis of the pediatric pineal gland is feasible and reveals enormous variation. Whereas gender effects are negligible, the pineal volume in children is dependant on age.

Maintained functionality of an implantable radiotelemetric blood pressure and heart rate sensor after magnetic resonance imaging in rats

Radiotelemetric sensors for in vivo assessment of blood pressure and heart rate are widely used in animal research. MRI with implanted sensors is regarded as contraindicated as transmitter malfunction and injury of the animal may be caused. Moreover, artefacts are expected to compromise image evaluation. In vitro, the function of a radiotelemetric sensor (TA11PA-C10, Data Sciences International) after exposure to MRI up to 9.4 T was assessed. The magnetic force of the electromagnetic field on the sensor as well as radiofrequency (RF)-induced sensor heating was analysed. Finally, MRI with an implanted sensor was performed in a rat. Imaging artefacts were analysed at 3.0 and 9.4 T ex vivo and in vivo. Transmitted 24 h blood pressure and heart rate were compared before and after MRI to verify the integrity of the telemetric sensor. The function of the sensor was not altered by MRI up to 9.4 T. The maximum force exerted on the sensor was 273 ± 50 mN. RF-induced heating was ruled out. Artefacts impeded the assessment of the abdomen and thorax in a dead rat, but not of the head and neck. MRI with implanted radiotelemetric sensors is feasible in principal. The tested sensor maintains functionality up to 9.4 T. Artefacts hampered abdominal and throacic imaging in rats, while assessment of the head and neck is possible.

[A child's birthday with consequences]

Foreign body ingestion is a common pediatric emergency and if the foreign body cannot be detected radiologically or endoscopically further investigations are required. In this article the case of a radiolucent, ingested foreign body (mini-candleholder of a birthday cake) is presented. The foreign body could not initially be identified via X-ray and endoscopy due to its parapharyngeal localization but was finally visualized by magnetic resonance imaging (MRI) which additionally uncovered the co-existence of acute mediastinal inflammation.

Dual-energy CT after peri-interventional subarachnoid haemorrhage: a feasibility study

PURPOSE

The aim was to assess the feasibility of dual-energy computed tomography (DE-CT) for detection of peri-interventional re-bleeding in patients with aneurysmal subarachnoid hemorrhage (re-SAH).

METHODS

For in vitro-analyses DE-CT of partially clotted blood intermixed with fresh blood containing contrast agent was performed. In a clinical setting, 4 patients routinely underwent DE-CT after suspected peri-interventional re-SAH. DE-CT source data images, iodine maps and virtual non-contrast images (VNC) were analyzed and regions-of-interest (ROI) measurements of density values were performed.

RESULTS

In vitro experiments demonstrated the feasibility of DE-CT to discriminate between blood with and without contrast agent. In all patients peri-interventional re-SAH was confirmed by detection of extravasated iodine within the subarachnoid spaces in post-interventional DE-CT. Dual-energy CT allowed the discrimination of old blood clots of the initial SAH and blood originating from peri-interventional re-SAH. After subtraction of the iodine-related high density signal, VNC images optimized the estimation of the true amount of subarachnoid blood.

CONCLUSION

Dual-energy CT allows the discrimination and subtraction of blood and iodine mixed within the subarachnoid spaces in patients with peri-interventional re-SAH. It helps to avoid overestimation of SAH after peri-interventional re-bleeding and therefore is a potentially valuable tool in the assessment of peri-interventional re-SAH.

[Current concepts for experimental micro-CT in small animals]

The number of publications describing the use of micro-computed tomography (microCT) for preclinical in vivo imaging of small animals has risen considerably within the last few years. The purpose of this review is to familiarize the reader with the basic principles of microCT, to present successful experimental approaches in order of the evaluated organ system, and to highlight limitations that need to be considered when planning microCT-based studies.

Successful granulocyte-colony stimulating factor treatment of Crohn's disease is associated with the appearance of circulating interleukin-10-producing T cells and increased lamina propria plasmacytoid dendritic cells

Granulocyte-colony stimulating factor (G-CSF) has proved to be a successful therapy for some patients with Crohn's disease. Given the known ability of G-CSF to exert anti-T helper 1 effects and to induce interleukin (IL)-10-secreting regulatory T cells, we studied whether clinical benefit from G-CSF therapy in active Crohn's disease was associated with decreased inflammatory cytokine production and/or increased regulatory responses. Crohn's patients were treated with G-CSF (5 microg/kg/day subcutaneously) for 4 weeks and changes in cell phenotype, cytokine production and dendritic cell subsets were measured in the peripheral blood and colonic mucosal biopsies using flow cytometry, enzyme-linked immunosorbent assay and immunocytochemistry. Crohn's patients who achieved a clinical response or remission based on the decrease in the Crohn's disease activity index differed from non-responding patients in several important ways: at the end of treatment, responding patients had significantly more CD4(+) memory T cells producing IL-10 in the peripheral blood; they also had a greatly enhanced CD123(+) plasmacytoid dendritic cell infiltration of the lamina propria. Interferon-gamma production capacity was not changed significantly except in non-responders, where it increased. These data show that clinical benefit from G-CSF treatment in Crohn's disease is accompanied by significant induction of IL-10 secreting T cells as well as increases in plasmacytoid dendritic cells in the lamina propria of the inflamed gut mucosa.

Analysis of mouse brain using a clinical 1.5 T scanner and a standard small loop surface coil

With increasing numbers of in vivo experiments in the field of neuroscience, the interest in methods for in vivo imaging of animal brains as small as those of mice has increased. Because highly specialized small bore scanners with high field strengths are not commonly available, clinical magnetic resonance imaging (cMRI) scanners have been used in the past to image rat and more recently also mouse brains in combination with specifically developed RF coils. These studies have demonstrated that imaging of small animal brains is feasible, and that tumor volumes measured by cMRI correlate well with histological tumor volume analysis. This protocol describes the cMRI settings at 1.5 T for imaging of mouse brain with resolutions up to 120 x 120 microm using an inexpensive, commercially available small loop surface coil. This allows easy establishment of a small animal MRI facility without the need for cost intensive dedicated small animal scanners or special custom made coils. In this study, we demonstrate high-resolution imaging of intracranial xenografts in a mouse glioma model and monitor the treatment effect of external field irradiation by cMRI.

Subcortical angiopathic encephalopathy in a German kindred suggests an autosomal dominant disorder distinct from CADASIL

A cerebral arteriopathy with subcortical infarcts and leukoencephalopathy is described with a pedigree suggestive for an autosomal dominant condition. In contrast to the vasculopathy designated with the acronym CADASIL, no deposits of granular osmiophilic material were detected in the vasculature and no point mutations in the NOTCH 3 gene were found. The disease occurred in a family living near Hamburg, Germany, and affected 11 women and 11 men over the last six generations. Onset of the disease was between the age of 12 and 50. Clinical symptoms included gait disturbances, dysarthria, sensomotoric deficits and a progressive dementia. Migraine-like complaints and epileptic seizures were observed in one case each. Cranial computer tomography and magnetic resonance imaging scans showed large confluent areas with decreased density in the white matter and small necroses in the brain stem, the basal ganglia and the white matter. A correlation with factors predisposing for vascular diseases could not be demonstrated. In five cases an autopsy was performed which disclosed an angiopathy affecting predominantly the penetrating arteries with consecutive lacunar infarcts, diffuse demyelination and rarefication of the subcortical white matter and degeneration of the pyramidal tracts. Histologically, the vessels showed concentric and excentric intimal proliferation, an elastosis and hyalinosis, splitting of the lamina elastica interna and a degeneration of the tunica muscularis. Electron microscopy revealed fragmentation and thickening of the basal lamina but electron-dense granules characteristic for CADASIL were not detected.

[Current controversies in the diagnosis and management of cerebral venous and dural sinus thrombosis]

Over the last few years, the results from clinical studies and innovative radiological approaches have significantly altered the management of patients with cerebral venous thrombosis. In contrast to previously held beliefs, cerebral venous thrombosis is considered to be a relatively benign disease with an overall favourable prognosis. Mortality is <10%, and the vast majority of patients recover completely. Although the efficacy of heparin has not been unequivocally proven, it is employed in most centres as the standard therapy. There are not sufficient data supporting long-term anticoagulation. In patients with a proven hypercoagulability syndrome, anticoagulation therapy is generally recommended for a period of 6 months. Whether patients with idiopathic thrombosis should also be treated remains controversial. Non-invasive MR and CT angiography techniques have largely replaced conventional angiography for initial evaluation and follow-up examinations. Both methods have a high sensitivity for cerebral venous thrombosis. Local fibrinolytic therapy or other aggressive recanalizing methods can not be generally recommended.