Roy König

Surgical and neurological complications in a series of 708 epilepsy surgical procedures.

OBJECTIVE There are few modern data on the complications of surgery for epilepsy from the neurosurgeons point of view. A survey of complications observed in a large current epilepsy surgery series is presented to facilitate the assessment of a risk:benefit ratio, which must be known when planning for epilepsy surgery and counseling patients. METHODS A series of 429 consecutive patients operated on during 6.5 years in the newly established University of Bonn epilepsy surgery program was, in part, retrospectively, and, in larger part, prospectively analyzed for complications originating from 279 invasive diagnostic procedures and 429 therapeutic procedures. Neuropsychological and psychiatric complications as well as the rate of failure to control seizures are not addressed in this article. RESULTS Two hundred and seventy-nine temporal operations, 59 frontal operations, 22 other extratemporal operations, 33 callosotomies, 3 multilobectomies, and 33 hemispherectomies were performed. Complications were grouped into general surgical and neurological complications. No mortality resulted from 708 invasive procedures. Two hundred and seventy-nine invasive diagnostic procedures (various combinations of strip, grid, and depth electrode insertions) resulted in 3.6% transient morbidity (2.9% surgical complications, 0.7% neurological complications) and 0.7% permanent morbidity (dysphasia). During 429 therapeutic procedures, 33 surgical complications were encountered. None of these resulted in permanent morbidity, except for the necessity for permanent shunt insertion in three patients. Wound infection was the most frequent surgical complication, but we were able to demonstrate a steady decrease during the 6.5-year observation period. The total rate of neurological complications in 429 therapeutic procedures was 5.4%, with 3.03% causing transient morbidity and 2.33% causing permanent morbidity. CONCLUSION Our data indicate that epilepsy surgery can be performed with an acceptable rate of resultant morbidity. The indications for epilepsy surgery, the learning curve determined, and the results from other series are discussed in the light of these figures.

Prospective Multicenter Cohort Study to Refine Management Recommendations for Women at Elevated Familial Risk of Breast Cancer: The EVA Trial

PURPOSE We investigated the respective contribution (in terms of cancer yield and stage at diagnosis) of clinical breast examination (CBE), mammography, ultrasound, and quality-assured breast magnetic resonance imaging (MRI), used alone or in different combination, for screening women at elevated risk for breast cancer. METHODS Prospective multicenter observational cohort study. Six hundred eighty-seven asymptomatic women at elevated familial risk (> or = 20% lifetime) underwent 1,679 annual screening rounds consisting of CBE, mammography, ultrasound, and MRI, read independently and in different combinations. In a subgroup of 371 women, additional half-yearly ultrasound and CBE was performed more than 869 screening rounds. Mean and median follow-up was 29.18 and 29.09 months. RESULTS Twenty-seven women were diagnosed with breast cancer: 11 ductal carcinoma in situ (41%) and 16 invasive cancers (59%). Three (11%) of 27 were node positive. All cancers were detected during annual screening; no interval cancer occurred; no cancer was identified during half-yearly ultrasound. The cancer yield of ultrasound (6.0 of 1,000) and mammography (5.4 of 1,000) was equivalent; it increased nonsignificantly (7.7 of 1,000) if both methods were combined. Cancer yield achieved by MRI alone (14.9 of 1,000) was significantly higher; it was not significantly improved by adding mammography (MRI plus mammography: 16.0 of 1,000) and did not change by adding ultrasound (MRI plus ultrasound: 14.9 of 1,000). Positive predictive value was 39% for mammography, 36% for ultrasound, and 48% for MRI. CONCLUSION In women at elevated familial risk, quality-assured MRI screening shifts the distribution of screen-detected breast cancers toward the preinvasive stage. In women undergoing quality-assured MRI annually, neither mammography, nor annual or half-yearly ultrasound or CBE will add to the cancer yield achieved by MRI alone.

Dual-Source Parallel Radiofrequency Excitation Body MR Imaging Compared with Standard MR Imaging at 3.0 T: Initial Clinical Experience

PURPOSE To prospectively compare the image quality and homogeneity of magnetic resonance (MR) images obtained by using a dual-source parallel radiofrequency (RF) excitation body MR imaging system with parallel transmission and independent RF shimming with the image quality and homogeneity of single-source MR images obtained by using standard sequences for routine clinical use in patients at 3.0 T. MATERIALS AND METHODS After institutional review board approval and informed patient consent were obtained, a dual-source parallel RF excitation 3.0-T MR system with independent RF shimming and parallel transmission technology was used to examine 28 patients and was compared with a standard 3.0-T MR system with single RF transmission. The RF power was distributed to the independent ports of the system body coil by using two RF transmission sources with full software control, enabling independent control of the phase and amplitude of the RF waveforms. Axial T2-weighted fast spin-echo (SE) and diffusion-weighted (DW) liver images, axial T2-weighted fast SE pelvic images, and sagittal T1- and T2-weighted fast SE spinal images were obtained by using dual- and single-source RF excitation. Two radiologists independently evaluated the images for homogeneity and image quality. Statistical significance was calculated by using the nonparametric Wilcoxon signed rank test. Interobserver agreement was determined by using Cohen kappa and Kendall tau-b tests. RESULTS Image quality comparisons revealed significantly better results with dual-source rather than single-source RF excitation at T2-weighted liver MR imaging (P = .001, kappa = 1.00) and better results at DW liver imaging at a statistical trend level (P = .066, tau-b > 0.7). Owing to reduced local energy deposition, fewer acquisitions and shorter repetition times could be implemented with dual-source RF excitation pelvic and spinal MR imaging, with image acquisition accelerating by 18%, 33%, and 50% compared with the acquisitions with single-source RF excitation. Image quality did not differ significantly between the two MR techniques (P > .05, tau-b > 0.5). CONCLUSION Dual-source parallel RF excitation body MR imaging enables reduced dielectric shading, improved homogeneity of the RF magnetic induction field, and accelerated imaging at 3.0 T.

Digital photography and 3D MRI-based multimodal imaging for individualized planning of resective neocortical epilepsy surgery

Summary:  Purpose: Invasive presurgical work up of pharmacoresistant epilepsies presumes integration of multiple diagnostic modalities into a comprehensive picture of seizure onset and eloquent brain areas. During resection, reliable transfer of evaluation results to the patients individual anatomy must be made. We investigated the value of digital photography–based grid localization in combination with preoperative three‐dimensional (3D) magnetic resonance imaging (MRI) for clinical routine.

Dual-source parallel RF transmission for clinical MR imaging of the spine at 3.0 T: intraindividual comparison with conventional single-source transmission.

PURPOSE To prospectively and intraindividually compare single-source radiofrequency (RF) excitation and dual-source parallel RF excitation in 3.0-T magnetic resonance (MR) imaging of the spine. MATERIALS AND METHODS Institutional review board approval and written informed patient consent were obtained. The RF power of a 3.0-T MR imaging system was distributed to two ports of the body coil of the system by using independent RF transmit channels. The maximum B(1) field strength for dual-source parallel RF excitation was maintained, as compared with single-source RF excitation. The repetition time was reduced according to the revised RF setup with dual-source parallel RF excitation while maintaining specific energy absorption limitations. Thirty patients were examined with and without dual-source parallel RF excitation. Diagnostic quality was assessed independently by two radiologists according to a four-point grading system. Image contrast ratios (CRs) were calculated between reference tissues and vertebrae for single-source RF excitation and dual-source parallel RF excitation. RESULTS The mean acceleration achieved with dual-source parallel RF excitation was 36% (range, 18%-50%). The total imaging duration of a three-station total spinal examination was reduced by one-third by using dual-source parallel RF transmission. For all cases investigated, diagnostic image quality without significant differences between the two methods and with a good interobserver agreement was achieved (Kendall tau-b, 0.50-0.84). The observed image contrast changes were predominantly small (<0.10 in 15 of 24 CRs), though they were significantly different (P < .05). CONCLUSION While shortening examination times by approximately one-third, the dual-source parallel RF transmission mode in MR imaging of the spine yielded diagnostic image quality comparable to that with the conventional single-source RF transmission mode.

Coregistration of digital photography of the human cortex and cranial magnetic resonance imaging for visualization of subdural electrodes in epilepsy surgery.

OBJECTIVE To develop a method for the coregistration of digital photographs of the human cortex with head magnetic resonance imaging (MRI) scans for invasive diagnostics and resective neocortical epilepsy surgery. METHODS Six chronically epileptic patients (two women, four men; mean age, 34 yr; age range, 20–43 yr) underwent preoperative three-dimensional (3D) T1-weighted MRI scans. Digital photographs of the exposed cortex were taken during implantation of subdural grid electrodes. Rendering software (Analyze 3.1; Biomedical Imaging Resource, Mayo Foundation, Rochester, MN) was used to create an MRI-based 3D model of the brain surface. Digital photographs were manually coregistered with the brain surface MRI model using the registration tool in the Analyze software. By matching the digital photograph and the brain surface model, the position of the subdural electrodes was integrated into the coordinate system of the preoperatively acquired 3D MRI dataset. RESULTS In all patients, the position of the labeled electrode contacts in relation to the cortical anatomy could be visualized on the 3D models of the cortical surface. At the time of resection, the resulting image of the coregistration process provides a realistic view of the cortex and the position of the subdural electrode. CONCLUSION The coregistration of digital photographs of the brain cortex with the results of 3D MRI data sets is possible. This allows for identification of anatomic details underlying the subdural grid electrodes and enhances the orientation of the surgeon.

Quantification of the magnetic resonance signal response to dynamic (C)O2‐enhanced imaging in the brain at 3 T: R*2 BOLD vs. balanced SSFP

To compare two magnetic resonance (MR) contrast mechanisms, R*2 BOLD and balanced SSFP, for the dynamic monitoring of the cerebral response to (C)O2 respiratory challenges.

Analysing the response in R2* relaxation rate of intracranial tumours to hyperoxic and hypercapnic respiratory challenges: initial results.

ObjectiveTo investigate the response in R2* relaxation rate of human intracranial tumours during hyperoxic and hypercapnic respiratory challenges.MethodsIn seven patients with different intracranial tumours, cerebral R2* changes during carbogen and CO2/air inhalation were monitored at 3 T using a dynamic multigradient-echo sequence of high temporal and spatial resolution. The R2* time series of each voxel was tested for significant change. Regions of interest were analysed with respect to response amplitude and velocity.ResultsThe tumours showed heterogeneous R2* responses with large interindividual variability. In the ‘contrast-enhancing’ area of five patients and in the ‘non-tumoral’ tissue most voxels showed a decrease in R2* for carbogen. For the ‘contrast-enhancing’ area of two patients hardly any responses were found. In areas of ‘necrosis’ and perifocal ‘oedema’ typically voxels with R2* increase and no response were found for both gases. For tissue responding to CO2/air, the R2* changes were of the same order of magnitude as those for carbogen. The response kinetic was generally attenuated in tumoral tissue.ConclusionThe spatially resolved determination of R2* changes reveals the individual heterogeneous response characteristic of intracranial human tumours during hyperoxic and hypercapnic respiratory challenges.

Evaluation of a Simplified Intravoxel Incoherent Motion (IVIM) Analysis of Diffusion-Weighted Imaging for Prediction of Tumor Size Changes and Imaging Response in Breast Cancer Liver Metastases Undergoing Radioembolization: A Retrospective Single Center Analysis.

AbstractTo investigate the value of a simplified intravoxel incoherent motion (IVIM) analysis for evaluation of therapy-induced tumor changes and response of breast cancer liver metastases (mBRC) undergoing radioembolization.In 21 females (mean age 54 years, range 43–72) with mBRC tumor size changes and response evaluation criteria in solid tumors (RECIST) response to 26 primary radioembolization procedures were analyzed. Standard 1.5-T liver magnetic resonance imaging including respiratory-gated diffusion-weighted imaging (DWI) with b0 = 0 s/mm2, b1 = 50 s/mm2, b2 = 800 s/mm2 before and 6 weeks after each treatment was performed. In addition to the apparent diffusion coefficient (ADC)(0,800), the estimated diffusion coefficient D′ and the perfusion fraction f′ were determined using a simplified IVIM approach. For each radioembolization, the 2 largest treated metastases (if available) were analyzed. Lesions were categorized according to size changes into group A (reduction of longest diameter [LD]) and group B (LD increase) after 3 months. Radioembolization procedures were further categorized into “response” (partial response and stable disease) and “nonresponse” (progressive disease) according to RECIST after 3 months. ADC and D′ are given in 10−6 mm2/s.Forty-five metastases were analyzed. Thirty-two lesions were categorized as A; 13 as B. Before therapy, group A lesions showed significantly larger f′-values than B (P = 0.001), but ADC(0,800) and D′ did not differ. After therapy, in group A lesions the ADC(0,800)- and D′-values increased and f′ decreased (P < 0.0001); in contrast in group B lesions f′ increased (P = 0.001). Groups could be differentiated by preinterventional f′ and by changes of D′ and f′ between pre and postinterventional imaging (area under the curve [AUC] of 0.903, 0.747 and 1.0, respectively).Preinterventional parameters did not differ between responders and nonresponders according to RECIST. ADC(0,800)- and D′-values showed a larger increase in responders compared with nonresponders (P = 0.013 and P = 0.001, respectively). After therapy f′-values decreased significantly in responders (P = 0.001). Good to excellent prediction of long-term RECIST response was possible by therapy-induced changes in LD, D′, and f′ (AUC 0.903, 0.879, and 0.867, respectively).A simplified IVIM model-based analysis of early post-treatment DWI can deliver additional information on tumor size changes and long-term RECIST response after radioembolization of mBRC. The estimated perfusion fraction f′ is better suited for response assessment than the conventional ADC(0,800) or D′. This can be useful to guide further treatment strategy.

Intracranial tumor response to respiratory challenges at 3.0 T: Impact of different methods to quantify changes in the MR relaxation rate R2*

To compare two ΔR2* quantification methods for analyzing the response of intracranial tumors to different breathing gases. The determination of changes in the magnetic resonance imaging (MRI) relaxation rate R2* (ΔR2*), induced by hyperoxic and hypercapnic respiratory challenges, enables the noninvasive assessment of blood oxygenation changes and vasoreactivity.