Mid-Term Outcomes of a Hybrid Approach Involving Open Surgery Plus TEVAR of the Descending Aorta in the Treatment of Complex Type A Dissection.

OBJECTIVES: Type A aortic dissection with true lumen collapse and malperfusion downstream is associated with a devastating prognosis. This study compares the clinical outcomes of two operative strategies for this disease: hybrid approach of ascending aorta (and hemiarch replacement) supplemented with retrograde stenting of the descending aorta (thoracic endovascular aortic repair [TEVAR]) and standard ascending aorta (and hemiarch) replacement without stent placement. METHODS: From January 1, 2016 to December 31, 2019, 81 patients with type A aortic dissection were studied. The hybrid technique was applied in 30 patients (group 1), while 51 patients received standard surgical repair (group 2). Patient demographics, clinical and operative findings, postoperative outcome, follow-up interventions, and mid-term survival were analyzed. RESULTS: Baseline characteristics were similar among the groups, except that more preoperative malperfusion was evident in group 1. The postoperative incidence of visceral malperfusion (0 vs. 15.7%, p = 0.02) and low cardiac output syndrome requiring extracorporeal membrane oxygenation support (3.3 vs. 19.6%, p = 0.04) was significantly less in group 1. In-hospital mortality was also significantly lower in group 1 as in group 2 (13.3 vs. 33.3%, p = 0.04). At follow-up, the need for secondary endovascular stenting (3.3 vs. 7.8%, p = 0.65) and surgical aortic reintervention (6.7 vs. 2.0%, p = 0.55) was comparable. One-year, 2-year, and 3-year survival rates were 83.3, 83.3, and 62.5% in group 1, and 58.7, 58.7, and 52.6% in group 2 (p = 0.05), respectively. CONCLUSION: The combination of open surgical replacement of the ascending aorta (and hemiarch) with TEVAR of the descending aorta for true lumen compromise is a feasible treatment option for patients with type A aortic dissection and is associated with a better perioperative outcome and improved mid-term survival rate.

Diagnostic Accuracy of Neuroimaging to Delineate Diffuse Gliomas within the Brain: A Meta-Analysis.

BACKGROUND: Brain imaging in diffuse glioma is used for diagnosis, treatment planning, and follow-up. PURPOSE: In this meta-analysis, we address the diagnostic accuracy of imaging to delineate diffuse glioma. DATA SOURCES: We systematically searched studies of adults with diffuse gliomas and correlation of imaging with histopathology. STUDY SELECTION: Study inclusion was based on quality criteria. Individual patient data were used, if available. DATA ANALYSIS: A hierarchic summary receiver operating characteristic method was applied. Low- and high-grade gliomas were analyzed in subgroups. DATA SYNTHESIS: Sixty-one studies described 3532 samples in 1309 patients. The mean Standard for Reporting of Diagnostic Accuracy score (13/25) indicated suboptimal reporting quality. For diffuse gliomas as a whole, the diagnostic accuracy was best with T2-weighted imaging, measured as area under the curve, false-positive rate, true-positive rate, and diagnostic odds ratio of 95.6%, 3.3%, 82%, and 152. For low-grade gliomas, the diagnostic accuracy of T2-weighted imaging as a reference was 89.0%, 0.4%, 44.7%, and 205; and for high-grade gliomas, with T1-weighted gadolinium-enhanced MR imaging as a reference, it was 80.7%, 16.8%, 73.3%, and 14.8. In high-grade gliomas, MR spectroscopy (85.7%, 35.0%, 85.7%, and 12.4) and 11C methionine-PET (85.1%, 38.7%, 93.7%, and 26.6) performed better than the reference imaging. LIMITATIONS: True-negative samples were underrepresented in these data, so false-positive rates are probably less reliable than true-positive rates. Multimodality imaging data were unavailable. CONCLUSIONS: The diagnostic accuracy of commonly used imaging is better for delineation of low-grade gliomas than high-grade gliomas on the basis of limited evidence. Improvement is indicated from advanced techniques, such as MR spectroscopy and PET.

32nd International Austrian Winter Symposium : Zell am See, the Netherlands. 20-23 January 2016.

TABLE OF CONTENTS: A1 68Ga-PSMA PET/CT in staging and restaging of Prostate Cancer Patients: comparative study with 18F-Choline PET/CTW Langsteger, A Rezaee, W Loidl, HS Geinitz, F Fitz, M Steinmair, G Broinger, L Pallwien-Prettner, M BeheshtiA2 F18 Choline PET - CT: an accurate diagnostic tool for the detection of parathyroid adenoma?L Imamovic, M Beheshti, G Rendl, D Hackl, O Tsybrovsky, M Steinmair, K Emmanuel, F Moinfar, C Pirich, W LangstegerA3 [18F]Fluoro-DOPA-PET/CT in the primary diagnosis of medullary thyroid carcinomaA Bytyqi, G Karanikas, M Mayerhöfer, O Koperek, B Niederle, M HartenbachA4 Variations of clinical PET/MR operations: An international survey on the clinical utilization of PET/MRIT Beyer, K Herrmann, J CzerninA5 Standard Dixon-based attenuation correction in combined PET/MRI: Reproducibility and the possibility of Lean body mass estimationI Rausch, P Rust, MD DiFranco, M Lassen, A Stadlbauer, ME Mayerhöfer, M Hartenbach, M Hacker, T BeyerA6 High resolution digital FDG PET/MRI imaging for assessment of ACL graft viabilityK Binzel, R Magnussen, W Wei, MU Knopp, DC Flanigan, C Kaeding, MV KnoppA7 Using pre-existing hematotoxicity as predictor for severe side effects and number of treatment cycles of Xofigo therapyA Leisser, M Nejabat, M Hartenbach, G Kramer, M Krainer, M Hacker, A HaugA8 QDOSE - comprehensive software solution for internal dose assessmentWencke Lehnert, Karl Schmidt, Sharok Kimiaei, Marcus Bronzel, Andreas KlugeA9 Clinical impact of Time-of-Flight on next-generation digital PET imaging of Yttrium-90 radioactivity following liver radioembolizationCL Wright, K Binzel, J Zhang, Evan Wuthrick, Piotr Maniawski, MV KnoppA10 Snakes in patients! Lessons learned from programming active contours for automated organ segmentationM Blaickner, E Rados, A Huber, M Dulovits, H Kulkarni, S Wiessalla, C Schuchardt, RP Baum, B Knäusl, D GeorgA11 Influence of a genetic polymorphism on brain uptake of the dual ABCB1/ABCG2 substrate [11C]tariquidarM Bauer, B Wulkersdorfer, W Wadsak, C Philippe, H Haslacher, M Zeitlinger, O LangerA12 Outcome prediction of temporal lobe epilepsy surgery from P-glycoprotein activity. Pooled analysis of (R)-[11C]-verapamil PET data from two European centresM Bauer, M Feldmann, R Karch, W Wadsak, M Zeitlinger, MJ Koepp, M-C Asselin, E Pataraia, O LangerA13 In-vitro and in-vivo characterization of [18F]FE@SNAP and derivatives for the visualization of the melanin concentrating hormone receptor 1M Zeilinger, C Philippe, M Dumanic, F Pichler, J Pilz, M Hacker, W Wadsak, M MitterhauserA14 Reducing time in quality control leads to higher specific radioactivity of short-lived radiotracersL Nics, B Steiner, M Hacker, M Mitterhauser, W WadsakA15 In vitro 11C-erlotinib binding experiments in cancer cell lines with epidermal growth factor receptor mutationsA Traxl, Thomas Wanek, Kushtrim Kryeziu, Severin Mairinger, Johann Stanek, Walter Berger, Claudia Kuntner, Oliver LangerA16 7-[11C]methyl-6-bromopurine, a PET tracer to measure brain Mrp1 function: radiosynthesis and first PET evaluation in miceS Mairinger, T Wanek, A Traxl, M Krohn, J Stanek, T Filip, M Sauberer, C Kuntner, J Pahnke, O LangerA17 18F labeled azidoglucose derivatives as "click" agents for pretargeted PET imagingD Svatunek, C Denk, M Wilkovitsch, T Wanek, T Filip, C Kuntner-Hannes, J Fröhlich, H MikulaA18 Bioorthogonal tools for PET imaging: development of radiolabeled 1,2,4,5-TetrazinesC Denk, D Svatunek, T Wanek, S Mairinger, J Stanek, T Filip, J Fröhlich, H Mikula, C Kuntner-HannesA19 Preclinical evaluation of [18F]FE@SUPPY- a new PET-tracer for oncologyT Balber, J Singer, J Fazekas, C Rami-Mark, N Berroterán-Infante, E Jensen-Jarolim, W Wadsak, M Hacker, H Viernstein, M MitterhauserA20 Investigation of Small [18F]-Fluoroalkylazides for Rapid Radiolabeling and In Vivo Click ChemistryC Denk, D Svatunek, B Sohr, H Mikula, J Fröhlich, T Wanek, C Kuntner-Hannes, T FilipA21 Microfluidic 68Ga-radiolabeling of PSMA-HBED-CC using a flow-through reactorS Pfaff, C Philippe, M Mitterhauser, M Hartenbach, M Hacker, W WadsakA22 Influence of 24-nor-ursodeoxycholic acid on hepatic disposition of [18F]ciprofloxacin measured with positron emission tomographyT Wanek, E Halilbasic, M Visentin, S Mairinger, B Stieger, C Kuntner, M Trauner, O LangerA23 Automated 18F-flumazenil production using chemically resistant disposable cassettesP Lam, M Aistleitner, R Eichinger, C ArtnerA24 Similarities and differences in the synthesis and quality control of 177Lu-DOTA-TATE, 177Lu -HA-DOTA-TATE and 177Lu-DOTA-PSMA (PSMA-617)H Eidherr, C Vraka, A Haug, M Mitterhauser, L Nics, M Hartenbach, M Hacker, W WadsakA25 68Ga- and 177Lu-labelling of PSMA-617H Kvaternik, R Müller, D Hausberger, C Zink, RM AignerA26 Radiolabelling of liposomes with 67Ga and biodistribution studies after administration by an aerosol inhalation systemU Cossío, M Asensio, A Montes, S Akhtar, Y te Welscher, R van Nostrum, V Gómez-Vallejo, J LlopA27 Fully automated quantification of DaTscan SPECT: Integration of age and gender differencesF VandeVyver, T Barclay, N Lippens, M TrochA28 Lesion-to-background ratio in co-registered 18F-FET PET/MR imaging - is it a valuable tool to differentiate between low grade and high grade brain tumor?L Hehenwarter, B Egger, J Holzmannhofer, M Rodrigues-Radischat, C PirichA29 [11C]-methionine PET in gliomas - a retrospective data analysis of 166 patientsN Pötsch, I Rausch, D Wilhelm, M Weber, J Furtner, G Karanikas, A Wöhrer, M Mitterhauser, M Hacker, T Traub-WeidingerA30 18F-Fluorocholine versus 18F-Fluorodeoxyglucose for PET/CT imaging in patients with relapsed or progressive multiple myeloma: a pilot studyT Cassou-Mounat, S Balogova, V Nataf, M Calzada, V Huchet, K Kerrou, J-Y Devaux, M Mohty, L Garderet, J-N TalbotA31 Prognostic benefit of additional SPECT/CT in sentinel lymph node mapping of breast cancer patientsS Stanzel, G Pregartner, T Schwarz, V Bjelic-Radisic, B Liegl-Atzwanger, R AignerA32 Evaluation of diagnostic value of TOF-18F-FDG PET/CT in patients with suspected pancreatic cancerS Stanzel, F Quehenberger, RM AignerA33 New quantification method for diagnosis of primary hyperpatahyroidism lesions and differential diagnosis vs thyropid nodular disease in dynamic scintigraphyA Koljevic Markovic, Milica Jankovic, V Miler Jerkovic, M Paskas, G Pupic, R Dzodic, D PopovicA34 A rare case of diffuse pancreatic involvement in patient with merkel cell carcinoma detected by 18F-FDGMC Fornito, D FamiliariA35 TSH-stimulated 18F-FDG PET/CT in the diagnosis of recurrent/metastatic radioiodine-negative differentiated thyroid carcinomas in patients with various thyroglobuline levelsP Koranda, H Polzerová, I Metelková, L Henzlová, R Formánek, E Buriánková, M KamínekA36 Breast Dose from lactation following I131 treatmentWH Thomson, C LewisA37 A new concept for performing SeHCAT studies with the gamma cameraWH Thomson, J O'Brien, G James, A NotghiA38 Whole body F-18-FDG-PET and tuberculosis: sensitivity compared to x-ray-CTH Huber, I Stelzmüller, R Wunn, M Mandl, F Fellner, B Lamprecht, M GabrielA39 Emerging role 18F-FDG PET-CT in the diagnosis and follow-up of the infection in heartware ventricular assist system (HVAD)MC Fornito, G LeonardiA40 Validation of Poisson resampling softwareWH Thomson, J O'Brien, G JamesA41 Protection of PET nuclear medicine personnel: problems in satisfying dose limit requirementsJ Hudzietzová, J Sabol, M Fülöp.

[Improved magnetic resonance myelography using image fusion]. / Verbesserte Magnetresonanz-Myelografie durch Bildfusion.

PURPOSE: To demonstrate that the disadvantage of missing anatomical information in heavily T2-weighted MR myelography images can be eliminated by image fusion and phase encoding in the coronal direction of the source images, resulting in MR myelography images comparable to the gold standard, i. e., post-myelography CT. MATERIALS AND METHODS: This study included 110 patients suffering from extradural pathologies of the cervical and lumbar spine. All patients were investigated using 3D MR myelography and post-myelography CT. The MRI data were post-processed using image fusion and reconstruction algorithms and were compared to the corresponding images of post-myelography CT. RESULTS: Our approach for visualization (3D MR myelography) was able to depict intradural structures in high spatial resolution and without artifacts. The results of our visualization approach were comparable to the gold standard - post-myelography CT. Anatomical correlation was reached by image fusion of different MR data sets. The required post-processing steps were performed quickly and were available on a commercial workstation. CONCLUSION: Image fusion of different MR data sets allows for visualization of 3D data sets with enhanced quality. The results for the visualization of MR myelography in particular are comparable to conventional myelography and post-myelography CT. The missing anatomical information in heavily T2-weighted MR myelography images can be compensated by image fusion with conventional MRI.

[Health economics evaluation of magnetic resonance imaging for the staging of prostate cancer for Austria and Germany]. / Gesundheitsökonomische Evaluation der Magnetresonanzbildgebung im Staging von Prostatakarzinomen für Österreich und Deutschland.

PURPOSE: The aim of this study was the health economics analysis of MR imaging in the preoperative staging of patients with prostate carcinoma (PCa). MATERIALS AND METHODS: The health economics analysis consisted of the following steps: modeling, determination of probabilities and parameters based on a detailed literature search, evaluation using the averages of the parameters, and sensitivity analyses of the results over the ranges of values. We performed a cost-utility analysis from health insurance's perspective for Austria and Germany. The population under investigation included patients with confirmed PCa. The alternative was a decision for therapy with or without staging using MR imaging. A localized PCa was treated by prostatectomy and locally advanced PCa by radiation/hormone therapy. The result parameters were quality adjusted life years (QALYs) and costs per patient. RESULTS: The evaluation showed that MR imaging is useful regarding costs and utilities prior to radical prostatectomy which is expensive and may be associated with serious clinical consequences. The costs per patient were lower by € 2635 and the utilities were higher by 0.099 QALYs. The strategy without MR imaging for staging was dominated by the strategy using MR imaging for staging in the evaluation using the base values and in almost all sensitivity analyses. CONCLUSION: For the parameters used and almost all scenarios of the sensitivity analysis, our decision-analytic model revealed a higher cost-utility ratio for the strategy using MR imaging for the staging of PCa.

Molecular imaging of cancer: MR spectroscopy and beyond.

Proton magnetic resonance spectroscopic imaging is a non-invasive diagnostic tool for the investigation of cancer metabolism. As an adjunct to morphologic and dynamic magnetic resonance imaging, it is routinely used for the staging, assessment of treatment response, and therapy monitoring in brain, breast, and prostate cancer. Recently, its application was extended to other cancerous diseases, such as malignant soft-tissue tumours, gastrointestinal and gynecological cancers, as well as nodal metastasis. In this review, we discuss the current and evolving clinical applications of proton magnetic resonance spectroscopic imaging. In addition, we will briefly discuss other evolving techniques, such as phosphorus magnetic resonance spectroscopic imaging, sodium imaging and diffusion-weighted imaging in cancer assessment.

[Health-economic evaluation of magnetic resonance imaging before biopsy for diagnosis of prostate cancer]. / Gesundheitsökonomische Evaluation einer Magnetresonanzbildgebung vor Biopsie zur Diagnose von Prostatakarzinomen.

PURPOSE: The aim of this study was the health-economic analysis of MR imaging in the diagnostics of suspicious prostate carcinoma (PCa) before execution of a first biopsy. MATERIALS AND METHODS: The health-economic analysis included four steps: modeling, determination of probabilities, evaluation, and sensitivity analyses. We performed an effectiveness analysis from the patient perspective as well as a cost-effectiveness and a cost-utility analysis from the health insurance perspective for Austria and Germany. The effectiveness and cost-effectiveness analysis used a hypothetical cohort of 100,000 patients. The result parameters were number of biopsies, number of detected PCa, and monetary costs. For the cost-efficiency analysis, the result parameters, quality-adjusted life years (QALYs) and costs, were calculated for an individual patient. RESULTS: The efficiency analysis showed that MRI before a first biopsy can prevent ca. 64,000 unnecessary biopsies/ 100,000 patients. The diagnostic efficiency was higher by a factor of 1.7. Due to MRI, eight PCas were additionally detected. From a health insurance perspective, MRI was not cost-effective. Extra costs of ca. 42 m. € per 100,000 patients and of 650 € per prevented biopsy were calculated. The costs per detected PCa were increased by 1395 €. The attainable QALYs were a little higher for the MRI alternative, which was therefore not dominated. CONCLUSION: Our results do not permit a clear recommendation for or against the application of MRI in the diagnostics of PCa. From the patient perspective, it is to be endorsed due to the higher medical efficiency. However, it is connected with higher health insurance costs.

Magnetic resonance spectroscopic imaging for visualization of the infiltration zone of glioma.

BACKGROUND AND PURPOSE: In conventional MR imaging, it is often difficult to delineate the heterogeneous structure of gliomas. Proton magnetic resonance spectroscopic imaging ((1)H-MRSI) is a noninvasive tool for investigating the spatial distribution of metabolic changes in brain lesions. The aim of this study was to assess the improvements in delineation of gliomas based on segmentation of metabolic changes measured with (1)H-MRSI. MATERIAL AND METHODS: Twenty patients with gliomas (WHO grade II and III) were examined using a standard (1)H-MRSI sequence. Metabolic maps for choline (Cho), N-acetyl-aspartate (NAA) and Cho/NAA ratios were calculated and segmented based on the assumption of a Gaussian distribution of the Cho/NAA values for normal brain. Areas of hyperintensity on T2-weighted (T2w) MR images were compared with the areas of the segmented tumor on Cho/NAA maps. Stereotactic biopsies were obtained from the MRSI/T2w difference areas. RESULTS: In all patients, the segmented MRSI tumor areas were greater than the T2w hyperintense areas, on average, by 20% (range 6-34%). In nine patients, biopsy sampling from the MRSI/T2w difference areas showed tumor infiltration ranging from 4-17% (mean 9%) tumor cells, in the areas detected only by MRSI. DISCUSSION AND CONCLUSION: Our method for automated segmentation of the lesion-related metabolic changes achieved significantly improved delineation for gliomas compared to routine clinical methods. We demonstrate that this method can improve delineation of tumor borders compared to routine imaging strategies in clinics. Metabolic images of the segmented tumor may thus be helpful for therapeutic planning.

Magnetic resonance spectroscopy in patients with Fabry and Gaucher disease.

OBJECTIVE: Fabry and Gaucher diseases are rare progressive inherited disorders of glycosphingolipid metabolism that affect multiple organ systems. The aim of this study was to investigate evidence for metabolic changes in the central nervous system involvement using proton magnetic resonance spectroscopic imaging. METHODS: Seven Fabry and eight Gaucher patients were included into this study. A two-dimensional, spectroscopic imaging method with an ultra-short echo-time of 11 ms was used at a 3T whole body magnet. Absolute metabolic values were retrieved using internal water scaling. Results were compared, with sex- and age-matched controls. RESULTS: In contrast to previous findings, absolute and relative metabolite values of N-acetyl-aspartate (NAA) or NAA/Creatine (Cr), Cr, Choline (Cho) or Cho/Cr and myo-Inositol (mI) or mI/Cr revealed no, differences between Fabry and Gaucher Type 1 (GD1) patients and controls. Average values were, 10.22, 6.32, 2.15 and 5.39 mMol/kg wet weight for NAA, Cr, Cho and mI, respectively. In this study, we found significantly decreasing NAA/Cho with increasing age in all three groups (Fabry, GD1, patients and healthy controls) (between 5 and 8% per decade). CONCLUSIONS: There were no changes of the quantified metabolites detected by MRS in normal appearing white matter. This study shows the importance of sex- and age-matched controls.

Multi-voxel magnetic resonance spectroscopy at 3 T in patients with idiopathic generalised epilepsy.

PURPOSE: The objective of our study was to gain further insight into the extent of local metabolic alterations in patients with idiopathic generalised epilepsy (IGE), respectively, the subgroup with generalised tonic-clonic seizures (GTCS). The extent of regional metabolic involvement perhaps indicates the key structures in generation of seizures and involvement of specific network of dysfunction. METHODS: Using the multi-voxel technique at a 3 T MRI Scanner metabolite levels of 25 age-matched healthy controls and 18 patients with GTCS were obtained from the basal ganglia, insular cortex, cingulum, hippocampus and along both hemispheres in the fronto-parietal white and grey matter. RESULTS: Group analysis of GTCS patients versus healthy controls revealed significant (p < 0.05) decrease of tNAA in the cortex of the central region and cingulum, but also in the thalami. Glx was elevated broadly in both hemispheres, in particular in central region, cingulum, insular cortex and left putamen, yet also in the right thalamus. Cho and mI demonstrated a significant coincidental decrease pronounced in the grey and white matter of the central region. Significant metabolic correlation (p ≤ 0.05) based on tNAA, respectively, Glx occurred between the thalamus and the central region, cingulum, putamen and medial frontal cortex. In patients with > 2 tonic-clonic seizures in the last 12 months a trend towards higher Glx and lower tNAA levels was observed. DISCUSSION: Our results demonstrate the altered metabolic interconnection of cerebral anatomic regions in patients with GTCS, in particular the major role of basal ganglia-central region relay in seizure generation.

In vivo quantification of intracerebral GABA by single-voxel (1)H-MRS-How reproducible are the results?

Gamma aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the human brain. It plays a decisive role in a variety of nervous system disorders, such as anxiety disorders, epilepsy, schizophrenia, insomnia, and many others. The reproducibility of GABA quantification results obtained with a single-voxel spectroscopy J-difference editing sequence with Point Resolved Spectroscopy localization (MEGA-PRESS) was determined on a 3.0 Tesla MR scanner in healthy adults. Eleven volunteers were measured in long- and short-term intervals. Intra- and inter-subject reproducibility were evaluated. Internal referencing of GABA+ to total creatine (tCr) and water (H(2)O), as well as two different post-processing methods for the evaluation (signal integration and time-domain fitting) were compared. In all subjects lower coefficient of variation and therefore higher reproducibility can be observed for fitting compared to integration. The GABA+/tCr ratio performs better than the GABA+/H(2)O ratio or GABA+ without internal referencing for both fitting and integration (GABA+/tCr: 13.3% and 17.0%; GABA+/H(2)O: 15.0% and 17.8%; GABA+: 19.2% and 21.7%). Four-day measurements on three subjects showed higher intra- than inter-subject reproducibility (GABA+/tCr approximately 10-12%). With a coefficient of variation of about 13% for inter-subject and 10-12% for intra-subject variability of GABA+/tCr, this technique seems to be a precise tool that can detect GABA confidently. The results of this study show the reproducibility limitations of GABA quantification in vivo, which are necessary for further clinical studies.

[Dynamic evaluation of the effects of quality management]. / Dynamische Evaluierung der Effekte von Qualitätsmanagement.

PURPOSE: Evaluation of the effects of quality management over time at a radiology department. MATERIALS AND METHODS: Data concerning the performance of the department, entered on a monthly basis, will be compared with entries in the error report system on the basis of time series analysis (regression models taking seasons and auto-correlation effects into account). The observation period consists of 46 homogeneous monthly time pulses. RESULTS: Effects of the suggestions and the total number of reports in the quality assurance system on the performance of the department can be observed with a two-month delay. This association is statistically highly significant (p < 0.01) and, because of the procedures used, not attributable to general developmental trends, seasonal fluctuations or autoregressive processes. CONCLUSION: Evaluation of quality assurance measures is a well justified demand and should be based on the analysis of data collected from quality assurance systems operating on a continuous basis over a long period of time. The analysis of data from a radiology department shows that quality assurance is reflected in the performance of the department.

(1)H-MRS profile in MRI positive- versus MRI negative patients with temporal lobe epilepsy.

INTRODUCTION: The objective of this study was to quantitate and compare ipsilateral total N-acetyl aspartate (tNAA), creatine (Cr), choline (Cho), myo-inositol (m-Ins) and glutamate plus glutamine (Glx) levels in the hippocampi of patients with temporal lobe epilepsy (TLE) with and without magnetic resonance imaging (MRI) evidence for mesial temporal sclerosis (MRI positive/negative). PATIENTS AND METHODS: Twenty-three age matched healthy controls and 26 consecutive patients with unilateral TLE, based on intensive 24h video-EEG, were investigated with proton magnetic resonance spectroscopy ((1)H-MRS) (17 with unilateral hippocampal sclerosis (HS) in MRI-MRI positive; 9 MRI negative). For statistical analysis one-way analysis of variance (ANOVA) with post hoc multiple comparisons and Bonferroni correction was applied. The significance level was based on p<0.05. RESULTS: The mean tNAA level ipsilateral to the seizure focus was significantly decreased in MRI negative, respectively MRI positive patients in comparison to healthy controls (p<0.001). The lowest tNAA level was noticed in the MRI positive group (p<0.001). Statistical analysis highlighted a clear "tNAA cut-off" (95% confidence interval) between MRI positive- and MRI negative patients and healthy controls. Mean level of Glx and m-Ins was not significantly elevated or reduced. However, in individual cases a significant elevation was noticed for Glx in MRI negative patients, respectively for m-Ins in MRI positive patients. CONCLUSION: MRI negative TLE patients have a different MRS profile than MRI positive patients (HS) with marginal but significant decrease of tNAA. Our results reveal a clear "tNAA cut-off" between the groups. The value of m-Ins and Glx in focus detection in TLE patients remains controversy.

High-field, high-resolution, susceptibility-weighted magnetic resonance imaging: improved image quality by addition of contrast agent and higher field strength in patients with brain tumors.

INTRODUCTION: To demonstrate intratumoral susceptibility effects in malignant brain tumors and to assess visualization of susceptibility effects before and after administration of the paramagnetic contrast agent MultiHance (gadobenate dimeglumine; Bracco Imaging), an agent known to have high relaxivity, with respect to susceptibility effects, image quality, and reduction of scan time. METHODS: Included in the study were 19 patients with malignant brain tumors who underwent high-resolution, susceptibility-weighted (SW) MR imaging at 3 T before and after administration of contrast agent. In all patients, Multihance was administered intravenously as a bolus (0.1 mmol/kg body weight). MR images were individually evaluated by two radiologists with previous experience in the evaluation of pre- and postcontrast 3-T SW MR images with respect to susceptibility effects, image quality, and reduction of scan time. RESULTS: In the 19 patients 21 tumors were diagnosed, of which 18 demonstrated intralesional susceptibility effects both in pre- and postcontrast SW images, and 19 demonstrated contrast enhancement in both SW images and T1-weighted spin-echo MR images. Conspicuity of susceptibility effects and image quality were improved in postcontrast images compared with precontrast images and the scan time was also reduced due to decreased TE values from 9 min (precontrast) to 7 min (postcontrast). CONCLUSION: The intravenous administration of MultiHance, an agent with high relaxivity, allowed a reduction of scan time from 9 min to 7 min while preserving excellent susceptibility effects and image quality in SW images obtained at 3 T. Contrast enhancement and intralesional susceptibility effects can be assessed in one sequence.

Metabolic changes in the normal ageing brain: consistent findings from short and long echo time proton spectroscopy.

OBJECTIVES: Sixty three healthy subjects were measured to assess dependence of brain metabolites on age using short- and long echo time spectroscopy in different brain regions. MATERIAL AND METHODS: Younger and elderly humans were measured with long echo time (TE=135ms) 3D-MR-spectroscopic imaging (MRSI) (10 subjects) and with ultra-short echo (TE=11ms) time 2D-MRSI (7 subjects). In addition, results from single voxel (1)H-spectroscopy (TE=20ms) of two cohorts of 46 healthy subjects were retrospectively correlated with age. RESULTS: 3D-MR SI revealed reduced NAA/Cr in the older group in the frontal lobe (-22%; p<0.01), parietal lobe (-28%; p<0.01) and semiovale (-9%; p<0.01) compared to the younger group. Cho/Cr was elevated in the semiovale (+35%; p<0.01) and in the n. lentiformis (+42%; p<0.01) in the older group. NAA/Cho was reduced in all regions measured, except the thalamus, in the older group compared to the younger group (from -21 to -49%; p<0.01). 2D-MRSI revealed decreased total NAA (-3.1% per decade; p<0.01) and NAA/Cr (-3.8% per decade; p<0.01), increased total Cho (+3.6% per decade; p<0.01) and Cho/Cr (+4.6% per decade; p<0.01) and increased total myo-Inositol (mI, +4.7% per decade; p<0.01) and mI/Cr (+5.4% per decade; p<0.01) and decreased NAA/Cho (-8% per decade; p<0.01) in semiovale WM. Results from single voxel spectroscopy revealed a significantly negative correlation of NAA/Cho in frontal (-13% per decade; p<0.01) and in temporal lobe (-7.4% per decade; p<0.01) as well as increased total Cr (10% per decade; p<0.01) in frontal lobe. Other results from single voxel measurements were not significant, but trends were comparable to that from multivoxel spectroscopy. CONCLUSION: Age-related changes measured with long echo time and short echo time 1H-MRS were comparable and cannot, therefore, be caused by different T2 relaxation times in young and old subjects, as suggested previously.

Correction of susceptibility artifacts in diffusion tensor data using non-linear registration.

Diffusion tensor imaging can be used to localize major white matter tracts within the human brain. For surgery of tumors near eloquent brain areas such as the pyramidal tract this information is of importance to achieve an optimal resection while avoiding post-operative neurological deficits. However, due to the small bandwidth of echo planar imaging, diffusion tensor images suffer from susceptibility artifacts resulting in positional shifts and distortion. As a consequence, the fiber tracts computed from echo planar imaging data are spatially distorted. We present an approach based on non-linear registration using Bézier functions to efficiently correct distortions due to susceptibility artifacts. The approach makes extensive use of graphics hardware to accelerate the non-linear registration procedure. An improvement presented in this paper is a more robust and efficient optimization strategy based on simultaneous perturbation stochastic approximation (SPSA). Since the accuracy of non-linear registration is crucial for the value of the presented correction method, two techniques were applied in order to prove the quality of the proposed framework. First, the registration accuracy was evaluated by recovering a known transformation with non-linear registration. Second, landmark-based evaluation of the registration method for anatomical and diffusion tensor data was performed. The registration was then applied to patients with lesions adjacent to the pyramidal tract in order to compensate for susceptibility artifacts. The effect of the correction on the pyramidal tract was then quantified by measuring the position of the tract before and after registration. As a result, the distortions observed in phase encoding direction were most prominent at the cortex and the brainstem. The presented approach allows correcting fiber tract distortions which is an important prerequisite when tractography data are integrated into a stereotactic setup for intra-operative guidance.

High-resolution contrast-enhanced, susceptibility-weighted MR imaging at 3T in patients with brain tumors: correlation with positron-emission tomography and histopathologic findings.

BACKGROUND AND PURPOSE: The purpose of this work was to demonstrate susceptibility effects (SusE) in various types of brain tumors with 3T high-resolution (HR)-contrast-enhanced (CE)-susceptibility-weighted (SW)-MR imaging and to correlate SusE with positron-emission tomography (PET) and histopathology. MATERIALS AND METHODS: Eighteen patients with brain tumors, scheduled for biopsy or tumor extirpation, underwent high-field (3T) MR imaging. In all of the patients, an axial T1-spin-echo (SE) sequence and an HR-SW imaging sequence before and after IV application of a standard dose of contrast agent (MultiHance) was obtained. Seven patients preoperatively underwent PET. The frequency and formation of intralesional SusE in all of the images were evaluated and correlated with tumor grade as determined by PET and histopathology. Direct correlation of SusE and histopathologic specimens was performed in 6 patients. Contrast enhancement of the lesions was assessed in both sequences. RESULTS: High-grade lesions demonstrated either high or medium frequency of SusE in 90% of the patients. Low-grade lesions demonstrated low frequency of SusE or no SusE. Correlation between intralesional frequency of SusE and histopathologic, as well as PET, tumor grading was statistically significant. Contrast enhancement was equally visible in both SW and SE sequences. Side-to-side comparison of tumor areas with high frequency of SusE and histopathology revealed that intralesional SusE reflected conglomerates of increased tumor microvascularity. CONCLUSIONS: 3T HR-CE-SW-MR imaging shows both intratumoral SusE not visible with standard MR imaging and contrast enhancement visible with standard MR imaging. Because frequency of intratumoral SusE correlates with tumor grade as determined by PET and histopathology, this novel technique is a promising tool for noninvasive differentiation of low-grade from high-grade brain tumors and for determination of an optimal area of biopsy for accurate tumor grading.

Changes in fiber integrity, diffusivity, and metabolism of the pyramidal tract adjacent to gliomas: a quantitative diffusion tensor fiber tracking and MR spectroscopic imaging study.

BACKGROUND AND PURPOSE: The underlying changes in the neuronal connectivity adjacent to brain tumors cannot always be depicted by conventional MR imaging. The hypothesis of this study was that preoperative sensorimotor deficits are associated with impairment in pyramidal fiber bundles. Hence, we investigated the potential of combined quantitative diffusion tensor (DT) fiber tracking and MR spectroscopic imaging (MRSI) to determine changes in the pyramidal tract adjacent to gliomas. MATERIALS AND METHODS: Quantitative DT fiber tracking and proton MRSI were performed in 20 patients with gliomas with WHO grades II-IV. Eight patients experienced preoperative sensorimotor deficits. Mean diffusivity (MD), fractional anisotropy (FA), and number of fibers per voxel (FpV) were calculated for the pyramidal tract of the ipsilateral and contralateral hemisphere. Metabolite concentrations for choline-containing compounds (Cho), creatine (Cr), and N-acetylaspartate (NAA) were computed, using LCModel, for all voxels located at the pyramidal tracts. RESULTS: For the whole pyramidal tract, quantitative DT fiber tracking resulted in significantly lower FpV and FA values (P < .001), but not MD values, for the ipsilateral hemisphere. For the section of the fiber bundle closest to the lesion, we found significantly decreased FpV and FA (P < .001) and increased MD (P = .002). MRSI showed, for the same volumes of interest, significantly decreased NAA (P = .001), increased Cho (P = .034) and Cho/NAA (P = .001) for the ipsilateral pyramidal tract. In patients suffering sensorimotor deficits, we found significantly lower FA (P = .022) and higher MD values (P = .026) and a strongly negative correlation between FA and MD (R = -0.710, P = .024) but no correlation in patients without deficits (R = 0.078, ns). CONCLUSION: Quantitative DTI was able to show significant differences in diffusivity of the pyramidal tract in patients with sensorimotor deficits in relation to patients without them. The additional use of proton MRSI may be helpful to discern whether these diffusivity changes in fiber tracts are caused by tumor infiltration or peritumoral edema.

Identifying the affected hemisphere by (1)H-MR spectroscopy in patients with temporal lobe epilepsy and no pathological findings in high resolution MRI.

Up to 30% of patients with temporal lobe epilepsy (TLE) remain without remarkable changes in MRI. In this study we investigated the role of (1)H-MR spectroscopy ((1)H-MRS) in lateralizing the affected hemisphere in the mentioned patient group. Twenty-two consecutive patients diagnosed with TLE were investigated by high resolution MRI and (1)H-MRS. We examined the incidence and diagnostic accuracy of temporal metabolite alterations determined by Linear Combination of Model Spectra (L C Model) via water reference. Metabolite values of each hemisphere of TLE patients were compared with healthy controls. Results of metabolite alterations were related to intensive video EEG focus localization. Reduction of N-acetylaspartate + N-acetylaspartyl-glutamate (tNAA) in the affected hemisphere revealed identification in six of nine patients (66%) with unilateral TLE. Group comparison revealed a significant reduction of tNAA (6.1+/-0.8*) in the involved temporal lobe compared with controls (6.67+/-0.4*, P=0.026). Choline levels were significantly increased in the affected hemisphere (1.42+/-0.17*) compared with healthy controls (1.22+/-0.17*, P=0.035). The results of our study show that (1)H-MRS is able to identify the affected hemisphere of MRI negative TLE patients and can be used as an additive tool in multimodal focus localization.

Short TE single-voxel 1H-MR spectroscopy of hippocampal structures in healthy adults at 1.5 Tesla--how reproducible are the results?

The purpose of our study was to evaluate inter- and intra-subject variability and scan-rescan reproducibility of single-voxel 1H-MR spectroscopy (1H-MRS) in hippocampal structures at 1.5 T field strength. Thirty healthy adults were studied bilaterally by optimized, standardized short echo time single-voxel 1H-MRS (PRESS, TE=30 ms, TR=3000 ms, oblique voxel orientation, voxel size 2 cm3). Spectral analysis and absolute metabolite quantitation of N-acetylaspartate+N-acetylaspartyl-glutamate (tNAA), choline (Cho), creatine (Cr), total glutamate plus glutamine (Glu+Gln) and myo-inositol (Ins) were carried out by LCModel. Inter- and intra-individual reproducibility of these metabolite values were investigated by calculation of mean, standard deviation, coefficient of variation (CV), and by analysis of variance for repeated measurements. The smallest CV in intersubject variability was obtained for tNAA, followed by Cr, Cho, Ins and Glu+Gln. The results of the analysis of variance for repeated measures in inter-subject variability showed a marginal effect of scan repetition for Cr (p=0.063) and Glu+Gln (p=0.082); the rescan of both metabolites showed slightly higher concentrations. No statistical significant effect of scan repetition was seen for tNAA (p=0.913), Cho (p=0.857), and Ins (p=0.826). Rescan led to the same results and gave proof of good reproducibility. Scan-rescan testing in one subject showed comparable results: tNAA (CV=4.8%), followed by Cr, Ins, Glu+Gln and Cho (all CV above 10%).