Search

The northern Swiss Alpine Foreland exemplifies a highly transient landscape characterized by multiple knickzones along the trunk valleys and distinct bedrock straths at their junction with tributary valleys. This landscape has evolved as a result of fast base level changes in response to repeated glaciations during the Quaternary. As the archives related to the evolution of this transient landscape are scarce, available quantitative information is limited, especially for the early and middle Pleistocene. In order to track the pace of the landscape evolution in the northern Swiss Alpine Foreland during the Pleistocene, in this study, we focus on the Deckenschotter sequences, the oldest Quaternary terrestrial sedimentary archives on the northern margin of the Central European Alps. These deposits have been morphostratigraphically divided into two: Höhere (Higher; HDS) and Tiefere (Lower; TDS) Deckenschotter. We analyzed seven different sites extending from Basel in the west to Schaffhausen in the east of Switzerland for the provenance signal, and we dated these archives by depth-profile and isochron-burial dating techniques with 10Be, 26Al, and 36Cl. Investigations on the petrographic compositions of the deposits revealed distinct provenances for the HDS and TDS deposits. During HDS time, the Alpine Rhine drained through Lake Constance and into the Danube River. Rerouting of the river toward the west and into the Upper Rhine Valley occurred between the end of HDS and the beginning of TDS accumulation. The results of the depth-profile and isochron-burial dating suggest that the HDS deposits accumulated at around 2 Ma as a result of a first widespread Alpine glaciation, whereas the TDS was deposited at around 1 Ma. Based on the provenance and the chronological information, we propose a scenario where the Rhine River captured the Alpine sources of the Danube and thus increased its runoff and enhanced its baseline lowering. Consequently, the landscape evolution has been accelerated possibly in response not only to the larger runoff but also to the climate change associated with the mid-Pleistocene revolution.

The Mediterranean is considered as an area which will be affected strongly by current climate change. However, temperature records for the past centuries which can contribute to a better understanding of future climate changes are still sparse for this region. Carbon isotope chronologies from tree-rings often mirror temperature history but their application as climate proxies is difficult due to the influence of the anthropogenic change in atmospheric CO2 on the carbon isotope fractionation during photosynthetic CO2 uptake. We tested the influence of different correction models accounting for plant response to increased atmospheric CO2 on four annually resolved long-term carbon isotope records (between 400 and 800 yr) derived from Corsican pine trees (Pinus nigra ssp. laricio) growing at ecologically varying mountain sites on the island of Corsica. The different correction factors have only a minor influence on the main climate signals and resulting temperature reconstructions. Carbon isotope series show strong correlations with summer temperature and precipitation. A summer temperature reconstruction (1448–2007 AD) reveals that the Little Ice Age was characterised by low, but not extremely low temperatures on Corsica. Temperatures have been to modern temperatures at around 1500 AD. The reconstruction reveals warm summers during 1480–1520 and 1950–2007 AD and cool summers during 1580–1620 and 1820–1890 AD.

The Swiss Deckenschotter (“cover gravels”) is the oldest Quaternary units in the northern Swiss Alpine Foreland. They are a succession of glaciofluvial gravel layers intercalated with glacial and/or overbank deposits. This lithostratigraphic sequence is called Deckenschotter because it “covers” Molasse or Mesozoic bedrock and forms mesa-type hill-tops. Deckenschotter occurs both within and beyond the extent of the Last Glacial Maximum glaciers. The Swiss Deckenschotter consist of two sub-units: Höhere (Higher) and Tiefere (Lower) Deckenschotter. Although the Höhere Deckenschotter sub-unit (HDS) is topographically higher than the Tiefere Deckenschotter, it is older. The only available age for the Swiss Deckenschotter is 2.5–1.8 Ma based on mammal remains found in HDS at the Irchel site. In this study, we present an exposure age for the topographically lowest HDS, calculated from a cosmogenic 10Be depth-profile. Our results show that the first phase of the Deckenschotter glaciations in the Swiss Alps terminated at least 1,020+80−120 ka ago, which is indicated by a significant fluvial incision. This line of evidence seems to be close to synchronous with the beginning of the Mid-Pleistocene Revolution, when the frequency of the glacial-interglacial cyclicity changed from 41 to 100 ka and the amplitude from low to high, between marine isotope stages 23 and 22., Swiss Journal of Geosciences, 107 (2-3), ISSN:1661-8734, ISSN:1661-8726

We present a new multi-parameter dataset from Corsican black pine growing on the island of Corsica in the Western Mediterranean basin covering the period AD 1410–2008. Wood parameters measured include tree-ring width, latewood width, earlywood width, cell lumen area, cell width, cell wall thickness, modelled wood density, as well as stable carbon and oxygen isotopes. We evaluated the relationships between different parameters and determined the value of the dataset for climate reconstructions. Correlation analyses revealed that carbon isotope ratios are influenced by cell parameters determining cell size, whereas oxygen isotope ratios are influenced by cell parameters determining the amount of transportable water in the xylem. A summer (June to August) precipitation reconstruction dating back to AD 1185 was established based on tree-ring width. No long-term trends or pronounced periods with extreme high/low precipitation are recorded in our reconstruction, indicating relatively stable moisture conditions over the entire time period. By comparing the precipitation reconstruction with a summer temperature reconstruction derived from the carbon isotope chronologies, we identified summers with extreme climate conditions, i.e. warm-dry, warm-wet, cold-dry and cold-wet. Extreme climate conditions during summer months were found to influence cell parameter characteristics. Cold-wet summers promote the production of broad latewood composed of wide and thin-walled tracheids, while warm-wet summers promote the production of latewood with small thick-walled cells. The presented dataset emphasizes the potential of multi-parameter wood analysis from one tree species over long time scales.

Re-evaluation of the river history, palaeosurface levels and exhumation history in northern Switzerland for the last 10 million years reveals that distinct morphotectonic events about 4.2 and 2.8 million years ago (Ma) caused major reorganisation of river networks and morphosculpture. As a result of the earlier formation of the Swiss Jura, potential relief energy in the piggy-back North Alpine Foreland Basin (NAFB) of northern central Switzerland south of the Jura fold belt was built up after 11–10 Ma. It was suddenly released by river capture at about 4.2 Ma when the Aare-Danube was captured by a tributary of the Rhone-Doubs river system which rooted southeast of the Black forest. This event triggered rapid denudation of weakly consolidated Molasse sediments, in the order of about 1 km, as constrained by apatite fission track data from drillholes in the NAFB. Likely mechanisms of river capture are (a) headward erosion of Rhone-Doubs tributaries, (b) uplift and rapidly increasing erosion of the Swiss Alps after about 5.3 Ma, and (c) gravel aggradation at the eastern termination of the Jura fold belt in the course of eastward and northward tilt of the piggy-back NAFB. A morphotectonic event between 4.2 and 2.5 Ma, probably at about 2.8 Ma, caused a phase of planation, accompanied by local gravel aggradation and temporary storage of Alpine debris. Between 2.8 and 2.5 Ma, the Aare-Rhone river system is cannibalised by the modern Rhine River, the latter later connecting with the Alpine Rhine River.

Stable carbon and oxygen isotopes in tree rings are considered as reliable climate archives as they provide past environmental information with high resolution. However, recent studies have shown that isotope chronologies may reveal a long-term age trend and be influenced by non-climatic factors as other tree-ring parameters as well. These trends can only be identified in chronologies measured on individual trees but not on pooled sample chronologies consisting of several trees. In order to test whether pooled chronologies from pine trees from the Island of Corsica (Mediterranean/France) can be used for climatic reconstructions, we compared calculated mean values from 5 individual trees with pooled chronologies from the same 5 individuals. Carbon and oxygen isotope chronologies for a 50-year interval with annual resolution and 400 years with decadal resolution were analysed in order to document secular changes in inter-tree variability and to test for age related trends in the isotope ratios. Pooled carbon and oxygen isotope series correspond well to chronologies based on mean values calculated from analyses of individual trees. Inter-tree variability in oxygen isotope ratios is higher than in carbon isotope ratios but remains relatively constant over time. Similarities between the isotope series of individual trees are stronger over the 400-year time scale documenting a common long-term signal in the isotope values. No long-term age related trends are observed. Oxygen isotope values of the juvenile phase are characterised by a remarkable decrease over 40–50 years, interpreted to be related to the less developed root system of the young trees. This age effect can be avoided by not considering the first 50 years from the chronologies. Our results confirm that pooled carbon and oxygen isotope chronologies from Pinus nigra can be used for environmental reconstructions without statistical detrending.

Aim To evaluate electrocardiogram (ECG)-gated quiescent-interval single-shot magnetic resonance angiography (QISS-MRA) for nonenhanced assessment of peripheral artery occlusive disease (PAOD) using contrast-enhanced MRA (CE-MRA) as the reference standard. Materials and methods Twenty-seven patients (mean age 66.6 ± 10.8 years) with PAOD were included in the study. QISS-MRA and CE-MRA of the lower extremity were performed using a 1.5 T MR scanner. In each patient, subjective image quality and the degree of stenosis were evaluated on a four-point scale for 15 predefined arterial segments. Results Twenty-five of the 27 patients were considered for analysis. Subjective image quality of QISS-MRA was significantly lower for the distal aorta, pelvic arteries, and femoral arteries as compared to CE-MRA (p < 0.01), while no significant difference was found for other vascular segments. The degree of stenosis was overestimated with QISS-MRA in 23 of 365 (6.3%) segments and underestimated in two of 365 (0.5%) segments. As compared to CE-MRA, QISS-MRA had a high sensitivity (98.6%), specificity (96%) as well as positive and negative predictive value (88.7 and 99.6%, respectively) for the detection of significant stenosis (≥50%). Conclusion ECG-gated QISS-MRA is a promising imaging technique for reliable assessment of PAOD without the use of contrast material.

Purpose To compare image quality of nonenhanced time-resolved 4D steady-state free precession MR angiography (4D SSFP MRA) of cerebral arteries at 1.5 T and 3 T. Materials and methods 12 healthy subjects (mean age 29.4 ± 6.9 years) were studied at both 1.5 T and 3 T. Two different positions of the acquisition slab were evaluated; in one acquisition the imaging slab included the carotid siphon (“Slow”), in the other acquisition the imaging slab was placed superior to the carotid siphon (“Shigh”). Subjective image quality of cerebral arteries was assessed independently by two readers on a 4-point scale. Relative Signal-to-Noise-Ratio (SNR) was determined for the M1 segment of the middle cerebral artery. Results Subjective image quality of the anterior cerebral artery (segments A1, A2) was significantly higher at 1.5 T as compared to 3 T, while 3 T provided significantly higher image quality for segment P3 of the posterior cerebral artery. For the middle cerebral artery (segments M1–M3), image quality was significantly higher at 1.5 T than at 3 T when the carotid siphon was included in the acquisition slab (“Slow”), while no significant difference was found between 1.5 T and 3 T with “Shigh”. Relative SNR was significantly higher at 1.5 T (23.1 ± 5.1) as compared to 3 T (12.1 ± 7.8) for “Slow” and significantly higher at 3 T (29.8 ± 5.9) than at 1.5 T (24.2 ± 3.6) for “Shigh”. Conclusion Our results indicate that 4D SSFP MRA should preferably be performed at 1.5 T with inclusion of the carotid siphon in the acquisition slab, which might be required for the assessment of intracranial collateral flow.

Die Computertomographie (CT) ist heute breit verfugbar und stellt eine wichtige und schnelle Methode zur Diagnostik akuter Lebererkrankungen, der Artdiagnostik fokaler Leberlasionen und der Planung interventioneller Therapiemasnahmen sowie der postinterventionellen Kontrolle dar. In den letzten Jahren hat die CT trotz des zunehmenden Stellenwerts der Magnetresonanztomographie (MRT) nicht an Bedeutung verloren. Durch den Einsatz unterschiedlicher Kontrastmittelphasen kann meist eine gute Charakterisierung von Raumforderungen erfolgen. Bei der Diagnostik des hepatozellularen Karzinoms (HCC) sollte beispielsweise immer ein triphasisches Untersuchungsprotokoll angewendet werden. Mit Einfuhrung der Dual-energy-CT hat die Sensitivitat in der Darstellung hyper- und hypovaskularisierter Leberlasionen zugenommen. Ebenfalls ist es durch virtuelle native Bilder moglich geworden, auf eine zusatzliche native Bildgebung zu verzichten, wodurch die Strahlenexposition des Patienten vermindert werden kann. Die PET/CT hat in der onkologischen Bildgebung den Vorteil, dass nahezu der gesamte Korper des Patienten abgebildet wird. Hier ist auch die Hauptindikation der PET/CT zu sehen (Ganzkorperstaging). Bei rein hepatischer Fragestellung hat die FDG-PET/CT unter Verwendung diagnostischer CT-Daten zwar eine hohere Genauigkeit als die CT alleine, ist der MRT jedoch unterlegen.

Background Periportal edema (PPE) can be seen in different clinical settings, including in patients following trauma. However, the underlying mechanisms and clinical significance in trauma patients still remain unclear. Purpose To determine the incidence of PPE in CT scans of trauma patients and to correlate PPE with trauma severity and different patterns of injury. Material and Methods We retrospectively analyzed contrast-enhanced spiral CT scans of 127 trauma patients that were referred to our Trauma Center Level I between January 2006 and June 2007. According to the Injury Severity Score (ISS), 70 patients with an ISS < 16 (minor trauma) were assigned to group 1 and 57 patients with an ISS ≥16 (major trauma) to group 2. Results The presence of PPE was significantly (p < 0.01) higher in group 2 (22 of 57 patients [38.6%]) than in group 1 (10 of 70 patients [14.3%]). In 29 patients PPE presented with a diffuse pattern and in three patients with a focal pattern, affecting only one liver lobe. In 14 patients PPE was found in absence of abdominal injuries. In addition, PPE was present in five patients with abdominal injuries but without liver injury. Conclusion PPE is seen significantly more often on abdominal CT scans following major traumas (ISS ≥ 16), but is not necessarily associated with liver injury.

Stable isotopes in tree rings have widely been used for palaeoclimate reconstructions since tree rings record climatic information at annual resolution. However, various wood components or different parts of an annual tree-ring may differ in their isotopic compositions. Thus, sample preparation and subsequent laboratory analysis are crucial for the isotopic signal retained in the final tree-ring isotope series used for climate reconstruction and must therefore be considered for the interpretation of isotope–climate relationships. This study focuses on wood of Corsican Pine trees (Pinus nigra ssp. laricio) as this tree species allows to reconstruct the long-term climate evolution in the western Mediterranean. In a pilot study, we concentrated on methodological issues of sample preparation techniques in order to evaluate isotope records measured on pooled whole tree-ring cellulose and whole tree-ring bulk wood samples. We analysed 80-year long carbon and oxygen chronologies of Corsican Pine trees growing near the upper tree line on Corsica. Carbon and oxygen isotope records of whole tree-ring bulk wood and whole tree-ring cellulose from a pooled sample of 5 trees were correlated with the climate parameters monthly precipitation, temperature and the self-calibrating Palmer Drought Severity Index (sc-PDSI). Results show that the offsets in carbon and oxygen isotopes of bulk wood and cellulose are not constant over time. Both isotopes correlate with climate parameters from late winter and summer. The carbon and oxygen isotope ratios of cellulose are more sensitive to climatic variables than those of bulk wood. The results of this study imply that extraction of cellulose is a pre-requisite for the reconstruction of high-resolution climate records from stable isotope series of P. nigra ssp. laricio.

[1] Winter circulation types under preindustrial and glacial conditions are investigated and used to quantify their impact on precipitation. The analysis is based on daily mean sea level pressure fields of a highly resolved atmospheric general circulation model and focuses on the North Atlantic and European region. We find that glacial circulation types are dominated by patterns with an east-west pressure gradient, which clearly differs from the predominantly zonal patterns for the recent past. This is also evident in the frequency of occurrence of circulation types when projecting preindustrial circulation types onto the glacial simulations. The elevation of the Laurentide ice sheet is identified as a major cause for these differences. In areas of strong precipitation signals in glacial times, the changes in the frequencies of occurrence of the circulation types explain up to 60% of the total difference between preindustrial and glacial simulations.

The Mediterranean is considered as an area which will be affected strongly by current climate change. However, temperature records for the past centuries which can contribute to a better understanding of future climate changes are still sparse for this region. We established a network of multi-century stable carbon isotope chronologies on Corsica to study long-term climate variation in the Western Mediterranean Basin. The chronologies show strong correlations with summer temperature and precipitation as well as summer cloud coverage. A summer temperature reconstruction (AD 1448–2008) reveals that the Little Ice Age was characterized by low, but not extremely low temperatures on Corsica. Relatively warm temperatures during the Maunder minimum may indicate a decoupling from climate cooling registered in northern latitudes. A comparison of the summer temperature reconstruction with a summer cloud coverage reconstruction indicates warm summers with reduced cloudiness during the periods AD 1480–1520 and 1950–2008 and cool and cloudy summers during AD 1580–1620 and 1820–1890. The distinct features of the reconstruction underline the uniqueness of the Corsican climate and highlight the necessity of a better temporal and spatial resolution of climate reconstructions for a more robust estimation of current climate change on a local scale.

PURPOSE To evaluate the influence of pulsatile blood flow on apparent diffusion coefficients (ADC) and the fraction of pseudodiffusion (F(P)) in the human kidney. MATERIALS AND METHODS The kidneys of 6 healthy volunteers were examined by a 3-T magnetic resonance scanner. Electrocardiogram (ECG)-gated and respiratory-triggered diffusion-weighted imaging (DWI) and phase-contrast flow measurements were performed. Flow imaging of renal arteries was carried out to quantify the dependence of renal blood flow on the cardiac cycle. ECG-triggered DWI was acquired in the coronal plane with 16 b values in the range of 0 s/mm(2) and 750 s/mm(2) at the time of minimum (MIN) (20 milliseconds after R wave) and maximum renal blood flow (MAX) (197 ± 24 milliseconds after R wave). The diffusion coefficients were calculated using the monoexponential approach as well as the biexponential intravoxel incoherent motion model and correlated to phase-contrast flow measurements. RESULTS Flow imaging showed pulsatile renal blood flow depending on the cardiac cycle. The mean flow velocity at MIN was 45 cm/s as compared with 61 cm/s at MAX. F(p) at MIN (0.29) was significantly lower than at MAX (0.40) (P = 0.001). Similarly, ADC(mono), derived from the monoexponential model, also showed a significant difference (P < 0.001) between MIN (ADC(mono) = 2.14 ± 0.08 × 10(-3) mm(2)/s) and MAX (ADC(mono) = 2.37 ± 0.04 × 10(-3) mm(2)/s). The correlation between renal blood flow and F(p) (r = 0.85) as well as ADC(mono) (r = 0.67) was statistically significant. CONCLUSION Temporally resolved ECG-gated DWI enables for the determination of the diffusion coefficients at different time points of the cardiac cycle. ADC(mono) and FP vary significantly among acquisitions at minimum (diastole) and maximum (systole) renal blood flow. Temporally resolved ECG-gated DWI might therefore serve as a novel technique for the assessment of pulsatility in the human kidney.

Computed tomography (CT) is now widely available and represents an important and rapid method for the diagnostics of acute liver disease, characterization of focal liver lesions, planning of interventional therapy measures and postintervention control. In recent years CT has not become less important despite the increasing value of magnetic resonance imaging (MRI). By the use of different contrast medium phases good characterization of space-occupying lesions can be achieved. For the diagnostics of hepatocellular carcinoma (HCC) a triphasic examination protocol should always be implemented. The introduction of dual energy CT increased the sensitivity of imaging of hypervascularized and hypovascularized liver lesions and by the use of virtual native imaging it has become possible to avoid additional native imaging which reduces the x-ray exposition of patients. Positron emission tomography (PET) has an advantage for imaging in oncology because nearly the complete body of the patient can be screened and this is the main indication for PET/CT (whole-body staging). For purely hepatic problems 18F-fluorodeoxyglucose (FDG)-PET/CT using diagnostic CT data has a higher precision than CT alone but is inferior to MRI.

Ziel: Das Ziel dieser Studie war die Evaluierung des Kontrastmittels Gadofosveset, welches in der Magnetresonanzangiografie (MRA) zur praoperativen Abklarung der renalen Gefasanatomie bei potenziellen Lebendnierenspendern (LNS) eingesetzt wurde. Material und Methoden: Von 28 potenziellen LNS (13 Manner, 15 Frauen; Durchschnittsalter 55,14 Jahre ± 11,97), die initial in diese prospektive Studie eingeschlossen wurden, sind 20 operiert und weiterfuhrend untersucht worden. Zur Beurteilung der Gefasanatomie und des harnableitenden Systems sind bei 1,5 Tesla nach Applikation von Gadofosveset 7 Aufnahmeserien einer 3D T 1-gewichteten FLASH-Sequenz zu festgelegten Zeitpunkten durchgefuhrt worden. Alle MRT wurden prospektiv von 2 Radiologen im Konsensusmodus vor dem chirurgischen Eingriff analysiert. ROI-basierende relative Signalrauschverhaltnisse in der Vena cava inferior und Aorta abdominalis wurden errechnet. Ergebnisse: Die MR-Datenakquisition wurde in allen potenziellen LNS vollstandig durchgefuhrt. Bei 8 Nierenspendern waren zusatzliche CT-Untersuchungen vorliegend, die zur Evaluation der gegenuberliegenden, nicht gespendeten Niere dienten, wodurch sich eine Gesamtanzahl von 28 untersuchten Nieren ergab. Die MRA zeigte 36 Nierenarterien, bei 8 akzessorische Arterien, die in 8 Patienten gefunden worden sind. Eine akzessorische Arterie und ein Fall einer fibromuskularen Dysplasie wurden von der MRA ubersehen. Die venose Anatomie und die ableitenden Harnwege sind mit der MRT-Untersuchung korrekt identifiziert worden. Daneben wurden durch die MRT-Untersuchung zwei Nierenzellkarzinome diagnostiziert. Auf einer Pro-Nieren-Basis betragen in Zusammenschau die Sensitivitat und der positive pradiktive Wert der gadofosveset-unterstutzten MRT-Untersuchung 92,9 % bzw. 100 %. Schlussfolgerung: Gadofosveset ermoglicht eine prazise Evaluation von potenziellen LNS. Purpose: The purpose of this study was to evaluate the blood pool contrast agent gadofosveset for MR angiography (MRA) of the renal vasculature in living kidney donors (LKD). Materials and Methods: Of the 28 consecutive potential LKDs (13 men, 15 women; mean age 55.14 years ± 11.97) initially included in this prospective study, 20 patients underwent surgery and were considered for further evaluation. 7 acquisitions of a 3D T 1-weighted FLASH sequence were performed following administration of gadofosveset for the assessment of the vascular anatomy and collecting system at predefined time points at 1.5 T. All MR exams were prospectively analyzed by 2 radiologists in consensus mode prior to surgery. In addition, ROI-based relative SNR measurements were performed in the vena cava inferior and abdominal aorta. Results: MR image acquisition was completed in all 20 potential living donors. In 8 donors an additional CT scan was available for further comparison with the collateral anatomy, resulting in a total of 28 analyzed kidneys. MRA disclosed 36 renal arteries, since 8 accessory arteries were found in 8 subjects. One accessory artery and one case of fibromuscular dysplasia were missed by MRA. The venous anatomy and the collecting system were assessed correctly with MRI. In addition, MRI diagnosed two renal cell carcinomas. The overall sensitivity and positive predictive value of gadofosveset-enhanced MRI on a per kidney basis were 92.9 % and 100 %, respectively. Conclusion: Gadofosveset enables accurate evaluation of potential LKDs.