Peter Schmidt

Localized Reversible Reduction of Apparent Diffusion Coefficient in Transient Hypoglycemia-Induced Hemiparesis

Background and Purpose— The pathophysiology of hypoglycemia shares a common mechanism with cerebral ischemia, but so far, little is known regarding MRI of humans with hypoglycemia. Methods— We report a patient with left hemiparesis and dysarthria associated with a blood glucose level of 1.7 mmol/L. The patient recovered completely after glucose infusion. Results— The initial diffusion-weighted imaging (DWI) showed increased signal intensities and a reduction of apparent diffusion coefficient (ADC) values localized in the corpus callosum (splenium) and asymmetrically in the corona radiata. After 48 hours, follow-up revealed complete recovery of DWI and ADC signal abnormalities. Conclusion— To our knowledge, this is the first presentation of a case with transient hypoglycemia-induced focal neurological deficits revealing completely reversible MRI changes in terms of disturbed DWI and ADC with a peculiar as yet undescribed topography.

Is Traditional Reading of the Bedside Chest Radiograph Appropriate To Detect Intraatrial Central Venous Catheter Position

BACKGROUND Traditionally, the positioning of central venous catheters (CVCs) outside the right atrium (RA) in patients receiving intensive care is determined by surrogate landmarks on bedside chest radiographs (CXRs). The validity of this method was examined by comparing readings of radiologists with the results of transesophageal echocardiography (TEE). METHODS Prospective study at university hospital. Two hundred thirteen adults scheduled for cardiothoracic surgery were randomized to right or left internal jugular vein catheterization under ECG guidance. One senior radiologist and two radiologists in training independently read the CXRs, and determined whether the CVC tip ended in the RA and measured the vertical distance from the CVC tip to the carina (TC-distance). RESULTS Two hundred twelve CVC tips could be identified by TEE. Only left-sided CVCs (n = 5) ended in the upper RA (2.4%). Three of those patients were shorter than 160 cm. Specificity was 94% for senior radiologist, 44% for the first radiologist in training, and 60% for the second radiologist in training. The TC-distance of intraatrial catheters was 39, 55, 59, 80, and 83 mm, respectively. Thus, a TC-distance < or = 55 mm ensured extraatrial tip position in four of five intraatrial CVCs (80%, p = 0.002). The TC-distance of extraatrial catheters ranged from - 26 to 102 mm. CONCLUSIONS Reading of a bedside CXR alone is not very accurate to identify intraatrial CVC tip position. TC-distance is a helpful marker, and its specificity is as good as that of an experienced radiologist if a cutoff value of 55 mm is chosen.

Detection and classification of different liver lesions: comparison of Gd-EOB-DTPA-enhanced MRI versus multiphasic spiral CT in a clinical single centre investigation.

OBJECTIVE To compare the diagnostic efficacy of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) vs. multidetector computed tomography (MDCT) for the detection and classification of focal liver lesions, differentiated also for lesion entity and size; a separate analysis of pre- and postcontrast images as well as T2-weighted MRI sequences of focal and exclusively solid lesions was integrated. METHODS Twenty-nine patients with 130 focal liver lesions underwent MDCT (64-detector-row; contrast medium iopromide; native, arterial, portalvenous, venous phase) and MRI (1.5-T; dynamic and tissue-specific phase 20 min after application of Gd-EOB-DTPA). Hepatic lesions were verified against a standard of reference (SOR). CT and MR images were independently analysed by four blinded radiologists on an ordinal 6-point-scale, determining lesion classification and diagnostic confidence. RESULTS Among 130 lesions, 68 were classified as malignant and 62 as benign by SOR. The detection of malignant and benign lesions differed significantly between combined and postcontrast MRI vs. MDCT; overall detection rate was 91.5% for combined MRI and 80.4% for combined MDCT (p<0.05). Considering all four readers together, combined MDCT achieved sensitivity of 66.2%, specificity of 79.0%, and diagnostic accuracy of 72.3%; combined MRI reached superior diagnostic efficacy: sensitivity 86.8%, specificity 94.4%, accuracy 90.4% (p<0.05). Differentiated for lesion size, in particular lesions <20mm revealed diagnostic benefit by MRI. Postcontrast MRI also achieved higher overall sensitivity, specificity, and accuracy compared to postcontrast MDCT for focal and exclusively solid liver lesions (p<0.05). CONCLUSION Combined and postcontrast Gd-EOB-DTPA-enhanced MRI provided significantly higher overall detection rate and diagnostic accuracy, including low inter-observer variability, compared to MDCT in a single centre study.

Brainstem representation of vestibular evoked myogenic potentials

OBJECTIVE Vestibular evoked myogenic potentials (VEMPs) are caused by a short-latency reflex recorded from averaged electromyography from the sternocleidomastoid muscle evoked by intense auditory clicks. Besides peripheral vestibulopathy, abnormal VEMPs can be caused by lesions of the brainstem. The aim of this study was to analyze the topology of ischemic brain lesions generating pathological VEMPs. METHODS Twenty-nine patients with brainstem infarcts were prospectively studied using VEMPs and MR imaging to evaluate the brainstem representation of the VEMP reflex. Individual brainstem lesions were projected to a standard MR-dataset for normalization. Probabilistic lesion maps were calculated. A digital brainstem atlas was fitted to the lesion maps. RESULTS Twelve patients showed unilaterally abnormal VEMPs, 10 patients had normal VEMPs. Seven patients with bilaterally absent VEMPs were not analyzed. Most lesions were located in the lateral medulla oblongata involving the spinal accessory nerve. Most lesions in the pons were associated to anterolateral parts of pyramidal tract fibers. In a few cases, lesions were located in the tegmental area of the pons, including the vestibular nuclei. CONCLUSIONS Abnormal VEMPs may be produced not only by peripheral vestibulopathy but also by brainstem lesions. VEMPs may be influenced by effects caused by lesions located above the level of the vestibular nuclei. SIGNIFICANCE This study adds to the knowledge of anatomical brainstem representation of VEMP.

Improvement of visualization of the intermediofacial nerve in the temporal bone using 3T magnetic resonance imaging: part 1: the facial nerve.

Purpose: This study examines the identifiability of the intratemporal motor facial nerve using 3-T and 1.5-T magnetic resonance imaging (MRI). Methods: Twenty subjects underwent T1- and T2-weighted MRI of the temporal bone. Acquisition was performed using a head coil at 3 and 1.5 T as well as a surface coil at 3 T. Layer thicknesses were 0.6 mm for 3-T and 0.8 mm for 1.5-T MRI. Eight topodiagnostically relevant facial nerve and branch structures were statistically evaluated. Results: The main trunk could be identified in all examinations. Sequences acquired with a head coil at 3 T yielded statistically significant superiority (P < 0.001) over 3-T surface coil and 1.5-T head coil measurements. The precise identifiability of the smallest structures (eg, stapedial nerve) succeeded best by means of T1-weighted 3-T MRI. Conclusions: Due to the precise identifiability of the smallest branches, 3-T MRI improves diagnostics particularly with regard to preoperative planning.

Delineation of alar ligament morphology: comparison of magnetic resonance imaging at 1.5 and 3 Tesla.

Rupture of the alar and transverse ligaments due to whiplash injury can lead to upper cervical spine instability and subsequent neurological deterioration. The purpose of this study was to evaluate the normal anatomical variability of the alar ligaments in asymptomatic individuals with 3-T magnetic resonance imaging (MRI) and to compare the findings with standard 1.5-T examinations. Thirty-six participants underwent 3-T and 1.5-T MRIs. Magnetic resonance imaging findings were analyzed by classifying the alar ligaments with regard to the features detectability, signal intensity compared with muscle tissue, homogeneity, shape, spatial orientation, and symmetry. Delineation of the alar ligaments was significantly better on 3-T images, which were subjectively preferred for evaluation. The alar ligaments showed great variability. In the majority of participants, the alar ligaments were hypointense to muscle tissue, inhomogeneous, and different in shape and orientation. A statistically significantly higher number of ligaments appeared symmetric on 3-T imaging, indicating that 1.5-T imaging may underestimate the proportion of patients with normal, symmetric ligaments. This study demonstrates that high-field 3-T MRI provides better visualization of the alar ligaments compared with 1.5-T MRI. The higher signal-to-noise ratio allows detection of small signal changes. A great interindividual variety of the MRI morphology of the alar ligaments was found in participants with no history of neck trauma. Further studies with more participants are necessary to evaluate alar ligament pathologies in patients with a history of whiplash injury.

Acute chest pain, heart failure, and eosinophilia in a woman without coronary disease.

This case report describes cardiac manifestations in a female patient with Churg–Strauss syndrome (CSS). Cardiac magnetic resonance imaging (CMRI) is the only imaging modality able to depict cardiac involvement with endomyocardial fibrosis, myocardial edema, pericarditis associated with pericardial effusions, and apical thrombi in the left or right ventricle. The encasement of the tricuspid valve caused by an obliterating thrombus of the right ventricular cavity, as observed in our patient, is very rare. CMRI is a potentially important diagnostic tool for the early detection of dangerous cardiac complications of CSS, allowing optimal and timely therapy and reducing the comorbidity of the disease.

Parenchymal and pleural findings in pulmonary embolism visualized by multi-channel detector computed tomography

Background: A normal computed tomography (CT) scan of the pulmonary arteries in the presence of parenchymal and pleural abnormalities may indicate a false-negative diagnosis of pulmonary embolism (PE). Multi-channel detector CT (MDCT) with thinner collimation may improve the detection of small peripheral PEs causing such abnormalities. Purpose: To investigate parenchymal and pleural findings visualized by contrast-enhanced MDCT in patients with and without PE, and to identify possible predictors of PE. Material and Methods: 129 patients with clinical signs of PE were included. In all patients an iopromide-enhanced 64-MDCT (64×0.625 mm collimation, pitch 1.375, overlapping reconstruction with a slice thickness of 0.625 mm, increment of overlapping slice reconstruction 0.43) was performed within 24 h after the onset of the symptoms. Results: MDCT detected PE in 45 of the 129 patients (35%). PE and parenchymal/pleural findings were localized predominantly within the lower lobes. Wedge-shaped opacities were significantly associated with PE (OR =3.00; 95% confidence interval 1.13–7.91). Vascular signs were only visualized in patients with PE. Nodules, consolidations, atelectasis, or effusions were not predictive of PE. Conclusion: The present MDCT study verified that parenchymal and pleural findings can be found in patients with or without PE. Wedge-shaped opacities and vascular signs were significantly associated with PE and therefore can be potential predictors of PE.

Embolization of a coronary aneurysm with support of a retrievable stent.

A 58-year-old woman presented for percutaneous occlusion of an incidentally found aneurysm of the left main trunk bifurcation. Angiography and computed tomography showed a dome of 11 mm and a neck of 6 mm communicating with the left anterior descending coronary artery (LAD) and the circumflexing