Clinical features of delayed endolymphatic hydrops and intralabyrinthine schwannoma : An imaging-confirmed comparative case series. English version

BACKGROUND

The aim of this study was to compare the clinical history and audiovestibular function test results of patients suffering from intralabyrinthine schwannoma or delayed endolymphatic hydrops (DEH).

PATIENTS AND METHODS

Five patients diagnosed with intralabyrinthine schwannoma by magnetic resonance imaging (MRI) and five patients diagnosed with DEH by locally enhanced inner ear MRI (LEIM) were retrospectively studied.

RESULTS

All patients with intralabyrinthine schwannoma or DEH initially presented with hearing loss. Vertigo occurred in two patients with intralabyrinthine schwannoma and in all patients with DEH. While audiometry achieved poorer results for patients with intralabyrinthine schwannomas, vestibular function tests revealed normal results in about half of the patients in both groups.

CONCLUSION

Patients with intralabyrinthine schwannomas may present with clinical symptoms similar to patients suffering from other inner ear disorders such as delayed endolymphatic hydrops and they may obtain similar findings in audiovestibular function tests. High-resolution magnetic resonance imaging with locally applied contrast agent may provide evidence of both underlying pathologies.

Rare diagnosis of telethoninopathy (LGMD2G) in a Turkish patient

Telethoninopathy is one of the rarest forms of Limb-girdle muscular dystrophy (LGMD). So far, only a small number of LGMD type 2 G (LGMD2G) patients have been described, mostly patients from Brazil. Here we present a 35-year-old female patient of Turkish ethnicity with LGMD2G due to a novel homozygous frame-shift mutation c.90_91del (p.Ser31Hisfs*11) in the telethonin gene, probably leading to truncated protein or nonsense mediated decay. Myalgia and walking on tiptoes were the first symptoms starting in early childhood, around age 22 proximal, later distal leg muscles became affected. Muscle biopsy showed a degenerative myopathy with lobulated fibers, creatine kinase levels were elevated to 1200 U/l. No cardiomyopathy has been detected but ventricular extrasystoles were treated with verapamil. Even though telethoninopathy represents a rare condition, testing for LGMD2G should be included into the diagnostic work-up of mild myopathies with early toe walking and distal and proximal involvement.

Test-retest reliability of prefrontal transcranial Direct Current Stimulation (tDCS) effects on functional MRI connectivity in healthy subjects

Transcranial Direct Current Stimulation (tDCS) of the prefrontal cortex (PFC) can be used for probing functional brain connectivity and meets general interest as novel therapeutic intervention in psychiatric and neurological disorders. Along with a more extensive use, it is important to understand the interplay between neural systems and stimulation protocols requiring basic methodological work. Here, we examined the test-retest (TRT) characteristics of tDCS-induced modulations in resting-state functional-connectivity MRI (RS fcMRI). Twenty healthy subjects received 20minutes of either active or sham tDCS of the dorsolateral PFC (2mA, anode over F3 and cathode over F4, international 10-20 system), preceded and ensued by a RS fcMRI (10minutes each). All subject underwent three tDCS sessions with one-week intervals in between. Effects of tDCS on RS fcMRI were determined at an individual as well as at a group level using both ROI-based and independent-component analyses (ICA). To evaluate the TRT reliability of individual active-tDCS and sham effects on RS fcMRI, voxel-wise intra-class correlation coefficients (ICC) of post-tDCS maps between testing sessions were calculated. For both approaches, results revealed low reliability of RS fcMRI after active tDCS (ICC_(2,1) = -0.09 - 0.16). Reliability of RS fcMRI (baselines only) was low to moderate for ROI-derived (ICC_(2,1) = 0.13 - 0.50) and low for ICA-derived connectivity (ICC_(2,1) = 0.19 - 0.34). Thus, for ROI-based analyses, the distribution of voxel-wise ICC was shifted to lower TRT reliability after active, but not after sham tDCS, for which the distribution was similar to baseline. The intra-individual variation observed here resembles variability of tDCS effects in motor regions and may be one reason why in this study robust tDCS effects at a group level were missing. The data can be used for appropriately designing large scale studies investigating methodological issues such as sources of variability and localisation of tDCS effects.

[MRI of the prostate]

New clinical and technological advances in the field of magnetic resonance imaging (MRI) and targeted image-guided biopsy techniques have significantly improved the detection, localization and staging as well as active surveillance of prostate cancer in recent years. Multiparametric MRI (mpMRI) is currently the main imaging technique for the detection, characterization and diagnostics of metastasizing prostate cancer and is of high diagnostic importance for local staging within the framework of the detection of prostate cancer.

Mutations in INPP5K, Encoding a Phosphoinositide 5-Phosphatase, Cause Congenital Muscular Dystrophy with Cataracts and Mild Cognitive Impairment

Phosphoinositides are small phospholipids that control diverse cellular downstream signaling events. Their spatial and temporal availability is tightly regulated by a set of specific lipid kinases and phosphatases. Congenital muscular dystrophies are hereditary disorders characterized by hypotonia and weakness from birth with variable eye and central nervous system involvement. In individuals exhibiting congenital muscular dystrophy, early-onset cataracts, and mild intellectual disability but normal cranial magnetic resonance imaging, we identified bi-allelic mutations in INPP5K, encoding inositol polyphosphate-5-phosphatase K. Mutations impaired phosphatase activity toward the phosphoinositide phosphatidylinositol (4,5)-bisphosphate or altered the subcellular localization of INPP5K. Downregulation of INPP5K orthologs in zebrafish embryos disrupted muscle fiber morphology and resulted in abnormal eye development. These data link congenital muscular dystrophies to defective phosphoinositide 5-phosphatase activity that is becoming increasingly recognized for its role in mediating pivotal cellular mechanisms contributing to disease.

Use of diffusion-weighted MRI to modify radiosurgery planning in brain metastases may reduce local recurrence

Stereotactic radiosurgery (SRS) is an effective and well tolerated treatment for selected brain metastases; however, local recurrence still occurs. We investigated the use of diffusion weighted MRI (DWI) as an adjunct for SRS treatment planning in brain metastases. Seventeen consecutive patients undergoing complete surgical resection of a solitary brain metastasis underwent image analysis retrospectively. SRS treatment plans were generated based on standard 3D post-contrast T1-weighted sequences at 1.5T and then separately using apparent diffusion coefficient (ADC) maps in a blinded fashion. Control scans immediately post operation confirmed complete tumour resection. Treatment plans were compared to one another and with volume of local recurrence at progression quantitatively and qualitatively by calculating the conformity index (CI), the overlapping volume as a proportion of the total combined volume, where 1 = identical plans and 0 = no conformation whatsoever. Gross tumour volumes (GTVs) using ADC and post-contrast T1-weighted sequences were quantitatively the same (related samples Wilcoxon signed rank test = -0.45, p = 0.653) but showed differing conformations (CI 0.53, p < 0.001). The diffusion treatment volume (DTV) obtained by combining the two target volumes was significantly greater than the treatment volume based on post contrast T1-weighted MRI alone, both quantitatively (median 13.65 vs. 9.52 cm3, related samples Wilcoxon signed rank test p < 0.001) and qualitatively (CI 0.74, p = 0.001). This DTV covered a greater volume of subsequent tumour recurrence than the standard plan (median 3.53 cm3 vs. 3.84 cm3, p = 0.002). ADC maps may be a useful tool in addition to the standard post-contrast T1-weighted sequence used for SRS planning.

Subclinical Disease Burden as Assessed by Whole-Body MRI in Subjects With Prediabetes, Subjects With Diabetes, and Normal Control Subjects From the General Population: The KORA-MRI Study

Detailed pathophysiological manifestations of early disease in the context of prediabetes are poorly understood. This study aimed to evaluate the extent of early signs of metabolic and cardio-cerebrovascular complications affecting multiple organs in individuals with prediabetes. Subjects without a history of stroke, coronary artery disease, or peripheral artery disease were enrolled in a case-control study nested within the Cooperative Health Research in the Region of Augsburg (KORA) FF4 cohort and underwent comprehensive MRI assessment to characterize cerebral parameters (white matter lesions, microbleeds), cardiovascular parameters (carotid plaque, left ventricular function, and myocardial late gadolinium enhancement [LGE]), and metabolic parameters (hepatic proton-density fat fraction [PDFF] and subcutaneous and visceral abdominal fat). Among 400 subjects who underwent MRI, 103 subjects had prediabetes and 54 had established diabetes. Subjects with prediabetes had an increased risk for carotid plaque and adverse functional cardiac parameters, including reduced early diastolic filling rates as well as a higher prevalence of LGE compared with healthy control subjects. In addition, people with prediabetes had significantly elevated levels of PDFF and total and visceral fat. Thus, subjects with prediabetes show early signs of subclinical disease that include vascular, cardiac, and metabolic changes, as measured by whole-body MRI after adjusting for cardiometabolic risk factors.

Cost-Effectiveness of Endovascular Stroke Therapy

Background and Purpose—

Endovascular therapy in addition to standard care (EVT+SC) has been demonstrated to be more effective than SC in acute ischemic large vessel occlusion stroke. Our aim was to determine the cost-effectiveness of EVT+SC depending on patients’ initial National Institutes of Health Stroke Scale (NIHSS) score, time from symptom onset, Alberta Stroke Program Early CT Score (ASPECTS), and occlusion location.

Methods—

A decision model based on Markov simulations estimated lifetime costs and quality-adjusted life years (QALYs) associated with both strategies applied in a US setting. Model input parameters were obtained from the literature, including recently pooled outcome data of 5 randomized controlled trials (ESCAPE [Endovascular Treatment for Small Core and Proximal Occlusion Ischemic Stroke], EXTEND-IA [Extending the Time for Thrombolysis in Emergency Neurological Deficits–Intra-Arterial], MR CLEAN [Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands], REVASCAT [Randomized Trial of Revascularization With Solitaire FR Device Versus Best Medical Therapy in the Treatment of Acute Stroke Due to Anterior Circulation Large Vessel Occlusion Presenting Within 8 Hours of Symptom Onset], and SWIFT PRIME [Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment]). Probabilistic sensitivity analysis was performed to estimate uncertainty of the model results. Net monetary benefits, incremental costs, incremental effectiveness, and incremental cost-effectiveness ratios were derived from the probabilistic sensitivity analysis. The willingness-to-pay was set to $50 000/QALY.

Results—

Overall, EVT+SC was cost-effective compared with SC (incremental cost: $4938, incremental effectiveness: 1.59 QALYs, and incremental cost-effectiveness ratio: $3110/QALY) in 100% of simulations. In all patient subgroups, EVT+SC led to gained QALYs (range: 0.47–2.12), and mean incremental cost-effectiveness ratios were considered cost-effective. However, subgroups with ASPECTS ≤5 or with M2 occlusions showed considerably higher incremental cost-effectiveness ratios ($14 273/QALY and $28 812/QALY, respectively) and only reached suboptimal acceptability in the probabilistic sensitivity analysis (75.5% and 59.4%, respectively). All other subgroups had acceptability rates of 90% to 100%.

Conclusions—

EVT+SC is cost-effective in most subgroups. In patients with ASPECTS ≤5 or with M2 occlusions, cost-effectiveness remains uncertain based on current data.

Classification of arterial and venous cerebral vasculature based on wavelet postprocessing of CT perfusion data

PURPOSE

The purpose of this study was to propose and evaluate a new wavelet-based technique for classification of arterial and venous vessels using time-resolved cerebral CT perfusion data sets.

METHODS

Fourteen consecutive patients (mean age 73 yr, range 17-97) with suspected stroke but no pathology in follow-up MRI were included. A CT perfusion scan with 32 dynamic phases was performed during intravenous bolus contrast-agent application. After rigid-body motion correction, a Paul wavelet (order 1) was used to calculate voxelwise the wavelet power spectrum (WPS) of each attenuation-time course. The angiographic intensity A was defined as the maximum of the WPS, located at the coordinates T (time axis) and W (scale/width axis) within the WPS. Using these three parameters (A, T, W) separately as well as combined by (1) Fisher's linear discriminant analysis (FLDA), (2) logistic regression (LogR) analysis, or (3) support vector machine (SVM) analysis, their potential to classify 18 different arterial and venous vessel segments per subject was evaluated.

RESULTS

The best vessel classification was obtained using all three parameters A and T and W [area under the curve (AUC): 0.953 with FLDA and 0.957 with LogR or SVM]. In direct comparison, the wavelet-derived parameters provided performance at least equal to conventional attenuation-time-course parameters. The maximum AUC obtained from the proposed wavelet parameters was slightly (although not statistically significantly) higher than the maximum AUC (0.945) obtained from the conventional parameters.

CONCLUSIONS

A new method to classify arterial and venous cerebral vessels with high statistical accuracy was introduced based on the time-domain wavelet transform of dynamic CT perfusion data in combination with linear or nonlinear multidimensional classification techniques.

White Paper: Radiological Curriculum for Undergraduate Medical Education in Germany

Purpose: Radiology represents a highly relevant part of undergraduate medical education from preclinical studies to subinternship training. It is therefore important to establish a content base for teaching radiology in German Medical Faculties. Materials and Methods: The German Society of Radiology (DRG) developed a model curriculum for radiological teaching at German medical universities, which is presented in this article. There is also a European model curriculum for undergraduate teaching (U-level curriculum of the European Society of Radiology). In a modular concept, the students shall learn important radiological core principles in the realms of knowledge, skills and competences as well as core scientific competences in the imaging sciences. Results: The curriculum is divided into two modules. Module 1 includes principles of radiation biology, radiation protection and imaging technology, imaging anatomy as well as the risks and side effects of radiological methods, procedures and contrast media. This module is modality-oriented. Module 2 comprises radiological diagnostic decision-making and imaging-based interventional techniques for various disease entities. This module is organ system-oriented. Conclusion: The curriculum is meant as a living document to be amended and revised at regular intervals. The curriculum can be used as a basis for individual curricular development at German Medical Faculties. It can be integrated into traditional or reformed medical teaching curricula. Key Points: • Radiology is an integral and important part of medical education.• The German Society of Radiology (DRG) developed a model curriculum for teaching radiology at German Medical Faculties to help students develop the ability to make medical decisions based on scientific knowledge and act accordingly.• This curriculum can be used for individual curricular development at medical departments. It is divided into two modules with several chapters. Citation Format: • Ertl-Wagner B, Barkhausen J, Mahnken AH et al. White Paper: Radiological Curriculum for Undergraduate Medical Education in Germany. Fortschr Röntgenstr 2016; 188: 1017 - 1023.

Prefrontal Transcranial Direct Current Stimulation for Treatment of Schizophrenia With Predominant Negative Symptoms: A Double-Blind, Sham-Controlled Proof-of-Concept Study

Negative symptoms are highly relevant in the long-term course of schizophrenia and are an important target domain for the development of novel interventions. Recently, transcranial direct current stimulation (tDCS) of the prefrontal cortex has been investigated as a treatment option in schizophrenia. In this proof-of-concept study, 20 schizophrenia patients with predominantly negative symptoms were randomized to either 10 sessions of add-on active (2 mA, 20min) or sham tDCS (anode: left DLPFC/F3; cathode: right supraorbital/F4). Primary outcome measure was the change in the Scale for the Assessment of Negative Symptoms (SANS) sum score; secondary outcomes included reduction in Positive and Negative Syndrome Scale (PANSS) scores and improvement of depressive symptoms, cognitive processing speed, and executive functioning. Sixteen patients underwent 4 functional connectivity magnetic resonance imaging (fcMRI) scans (pre and post 1st and pre and post 10th tDCS) to investigate changes in resting state network connectivity after tDCS. Per-protocol analysis showed a significantly greater decrease in SANS score after active (-36.1%) than after sham tDCS (-0.7%). PANSS sum scores decreased significantly more with active (-23.4%) than with sham stimulation (-2.2%). Explorative analysis of fcMRI data indicated changes in subgenual cortex and dorsolateral prefrontal cortex (DLPFC) connectivity within frontal-thalamic-temporo-parietal networks. The results of this first proof-of-concept study indicate that prefrontal tDCS may be a promising intervention for treatment of schizophrenia with predominant negative symptoms. Large-scale randomized controlled studies are needed to further establish prefrontal tDCS as novel treatment for negative symptoms in schizophrenia.

A Novel Imaging Marker for Small Vessel Disease Based on Skeletonization of White Matter Tracts and Diffusion Histograms

OBJECTIVE

To establish a fully automated, robust imaging marker for cerebral small vessel disease (SVD) and related cognitive impairment that is easy to implement, reflects disease burden, and is strongly associated with processing speed, the predominantly affected cognitive domain in SVD.

METHODS

We developed a novel magnetic resonance imaging marker based on diffusion tensor imaging, skeletonization of white matter tracts, and histogram analysis. The marker (peak width of skeletonized mean diffusivity [PSMD]) was assessed along with conventional SVD imaging markers. We first evaluated associations with processing speed in patients with genetically defined SVD (n = 113). Next, we validated our findings in independent samples of inherited SVD (n = 57), sporadic SVD (n = 444), and memory clinic patients with SVD (n = 105). The new marker was further applied to healthy controls (n = 241) and to patients with Alzheimer's disease (n = 153). We further conducted a longitudinal analysis and interscanner reproducibility study.

RESULTS

PSMD was associated with processing speed in all study samples with SVD (p-values between 2.8 × 10(-3) and 1.8 × 10(-10) ). PSMD explained most of the variance in processing speed (R(2) ranging from 8.8% to 46%) and consistently outperformed conventional imaging markers (white matter hyperintensity volume, lacune volume, and brain volume) in multiple regression analyses. Increases in PSMD were linked to vascular but not to neurodegenerative disease. In longitudinal analysis, PSMD captured SVD progression better than other imaging markers.

INTERPRETATION

PSMD is a new, fully automated, and robust imaging marker for SVD. PSMD can easily be applied to large samples and may be of great utility for both research studies and clinical use. Ann Neurol 2016;80:581-592.