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The length of the solar activity cycle fluctuates considerably. The temporal evolution of the corresponding cycle phase, that is, the deviation of the epochs of activity minima or maxima from strict periodicity, provides relevant information concerning the physical mechanism underlying the cyclic magnetic activity. An underlying strictly periodic process (akin to a perfect "clock"), with the observer seeing a superposition of the perfect clock and a small random phase perturbation, leads to long-term phase stability in the observations. Such behavior would be expected if cycles were synchronized by tides caused by orbiting planets or by a hypothetical torsional oscillation in the solar radiative interior. Alternatively, in the absence of such synchronization, phase fluctuations accumulate and a random walk of the phase ensues, which is a typical property of randomly perturbed dynamo models. Based on the sunspot record and the reconstruction of solar cycles from cosmogenic C14, we carried out rigorous statistical tests in order to decipher whether there exists phase synchronization or random walk. Synchronization is rejected at significance levels of between 95% (28 cycles from sunspot data) and beyond 99% (84 cycles reconstructed from C14, while the existence of random walk in the phases is consistent with all data sets. This result strongly supports randomly perturbed dynamo models with little inter-cycle memory., Comment: Astronomy & Astrophysics, in press

Diffusion-weighted imaging (DWI) can be used to quantitatively assess functional parameters in rectal carcinoma that are relevant for prognosis and treatment response assessment. However, there is no consensus on the histopathological background underlying the findings derived from DWI. The aim of this study was to perform a comparison of DWI and histologic parameters in two groups of rectal carcinoma patients without (n=12) and after (n=9) neoadjuvant chemoradiotherapy (CRT). The intravoxel incoherent motion (IVIM) model was used to calculate the diffusion coefficient D and the perfusion fraction f in rectal carcinoma, the adjacent rectum and fat in the two patient groups. Immunohistological analysis was performed to assess the cellularity, vascular area fraction and vessel diameter for comparison and correlation. Out of 36 correlations between parameters from DWI and histology, four were found to be significant. In rectal carcinoma of patients without CRT, the diffusion D and the perfusion f correlated with the vascular area fraction, respectively, which could not be found in the group of patients who received CRT. Further correlations were found for the rectum and fat. Histological evaluation revealed significant differences between the tissues on the microscopic level concerning the cellular and vascular environment that influence diffusion and perfusion. In conclusion, DWI produces valuable biomarkers for diffusion and perfusion in rectal carcinoma and adjacent tissues that are highly dependent of the underlying cellular microenvironment influenced by structural and functional changes as well as the administered treatment, and consequently can be beyond histological ascertainability.

For advanced therapies, the same basic principles for assessment apply as for any other biotechnological medicinal product. Nevertheless, the extent of data for quality, safety, and efficacy can be highly specific. Until recently, advanced therapies were not uniformly regulated across Europe, e.g., tissue engineered products were regulated either as medicinal products or medical devices. Thus, for some products no data from clinical studies are available, e.g., for autologous chondrocyte products. The draft guideline on Good Clinical Practice for clinical trials with advanced therapies describes specific additional requirements, e.g., ensuring traceability. Most clinical studies with advanced therapies in Germany are still in early phase I or II trials with highly divergent types of products and clinical indications. The Committee for Advanced Therapies (CAT) at the European Medicines Agency (EMEA) has been established to meet the scientific and regulatory challenges with advanced therapies.

The newly qualified IRS facility for the determination of total and spectral emissivities and its recent numerical optimization is described. Values of measured total emissivities of the ceramics HfO2, Al2O3, Yt2O3 and the metals/alloys tungsten, TZM and PM1000 in the temperature regime of 750–1800 K are given. The drastic influence of the oxidation state of PM1000 on the emissivity is discussed. Additionally, results of an investigation of the influence of surface roughness and surface topology on emissivity are presented. Therefore, three SSiC samples with surface roughness from R q = 0.05 to 0.66 have been prepared using common finishing operations. The tests showed that the emissivity increased about 10% with an increase of the surface roughness even in the regime where R q values are in the same magnitude or much smaller than the maximum emitting wavelength. Recombination coefficients for the abovementioned materials have been determined in pure oxygen plasma. The methodology for the determination of recombination coefficients of ceramic and metallic thermal protection system (TPS) materials in single species gases used at IRS and its latest improvements is presented. Test results for the recombination coefficients in oxygen plasma are shown between 1469 and 2072 K.

This study deals with a manned mission which focuses on building an orbital station around Mars. The advantages in comparison to direct-landing scenarios are outlined and the necessary technology is described. The orbiting station prohibits contamination of and from the Red Planet and houses six astronauts in a 1100 days journey to Mars providing three pressurized modules: two of them will remain in a Low Mars Orbit for further human missions while the third module is used as an Earth Return Vehicle. A Bimodal Nuclear Thermal Propulsion System is used also for electrical power production. An advanced Environment Control and Life Support System, the necessary radiation shielding, human factors and crew selection criteria have been studied. The described partly reusable Mars Landing Module allows highest possible flexibility in the choice of landing scenario. The overall mission budgets in the fields of mass, power and costs have been estimated. © 2005 Elsevier Ltd. All rights reserved.

Human keratinocytes are fully competent cells of the vitamin D (VD) hormone system. They have the capacity to generate VD, to convert it to hormonally active 1alpha,25(OH)(2)D(3) and subsequently, to metabolize the hormone by self-induced CYP24. These reactions generate a cascade of highly transient products and, eventually terminate biologic activity. To elucidate regulatory principles in the VD cascade in more detail, we made use of novel selective CYP24 inhibitors, recently synthesized by our group. Here, we describe the effects of VID400 and SDZ 89-443 on the metabolism of 20 nM (3)H-25(OH)D(3) in human keratinocytes, analyzed by sensitive HPLC methods. First, we present evidence that freshly generated 1alpha,25(OH)(2)D(3) does not down-regulate 1alpha-hydroxylation, as commonly assumed. The transient time course of 1alpha,25(OH)(2)D(3), could be explained by its fast 24-hydroxylation to polar products, undetectable by usual HPLC-analysis of organic extracts. On inhibition of CYP24, 1alpha-hydroxylation continued throughout extended periods, indicating its constitutive nature. Asking whether 1alpha,25(OH)(2)D(3) derived metabolites [1alpha,25(OH)(2)-3epi-D(3), 1alpha,24(R),25(OH)(3)D(3), 1alpha,25(OH)(2)-24oxo-D(3), 1alpha,23(S),25(OH)(3)-24-oxo-D(3) and calcitroic acid] would regulate 1alpha-hydroxylase, we pre-treated cells with 20 nM of these metabolites for 5 h and 24 h. Subsequent incubation with (3)H-25(OH)D(3) demonstrated that neither metabolite substantially impaired 1alpha-hydroxylase, while all of them transiently induced CYP24 activity. Analyzing the effects of VID400 on the kinetics of (3)H-25(OH)D(3), we showed that 1alpha-hydroxylation rather than 24-hydroxylation was rate-limiting in the C-24 oxidation pathway - again suggesting constitutive expression of 1alpha-hydroxylase. CYP24 inhibitors effectively increased the levels and lifetime of all transient 1alpha-hydroxylated metabolites, especially of 1alpha,25(OH)(2)-3epi-D(3) that became the predominant lipid soluble metabolite. Highly increased levels of 1alpha,23(S),25(OH)(3)-24-oxo-D(3), the metabolite preceding side chain cleavage, indicated involvement of CYP24 also in the terminal step of the cascade. Besides using inhibitors of CYP24 as tools to explore mechanisms in the VD cascade, they also appear to be valuable to discover the intrinsic biologic functions of distinct metabolites.

Pulsed stress reliability investigations have been carried out for Pt GaAs Schottky diodes. A thermal characterisation of the devices is performed using a numerical, coupled electrical thermal SPICE simulator. Different degradation mechanisms have been identified investigated. A comparison between thermal stress and electrical stress shows an influence of the operating current density and the anode diameter on the device degradation. Analytical calculations, simulation results, and results from the Wunsch-Bell model have been compared.

Purpose: Sonographical methods were often used as an alternative to radiologic cystourethrography when diagnosing female urinary stress incontinence. The anatomical changes of the bladder neck and the urethra are readily visualised by both methods, but there is no standardisation of ultrasound measurement procedures. The aim of the study was to investigate two different ultrasound methods of measurement, to find out a reproducible and standardised evaluation of introital sonography. Study design: Ultrasonic examination was performed by two independent and well-trained investigators on 46 patients at rest and during Valsalva's manoeuvre, using a 5-MHz transducer. The scanner was placed in the vaginal introitus in a sagittal orientation and positioned so as to obtain a view of the bladder, bladder base, urethrovesical junction, and the pubis. The first method needs a midline through the chondral part of the pubis for a rectangular coordinate system. The bladder neck was located by means of distance measurements. In addition, funnelling of the proximal urethra and the urethrovesical angle β were noted. For the second method we assume that the transducer is exactly inserted along the body axis. In this case a horizontal reference line through the upper point of the pubis (bone or chondral part) can be defined, as well as a rectangular coordinate system for the determination of the bladder neck. Using the second method it is not necessary to visualise the chondral part of the pubis. Results: In the first method the whole chondral part of the pubis could be seen in 61% (28 patients). Furthermore, we needed more time for this procedure than for the second method (13.1 to 20.7s versus 10.9 to 13.7s), so that the first method cannot be recommended as a reproducible procedure. There was a high significant inter-examiner correlation in the second method at rest and during strain (Pearson correlation coefficient r values from 0.5730 to 0.9093). Conclusion: Introital sonography provides reproducible information. For a standardised evaluation it is necessary that the transducer is inserted exactly along the body axis so that a horizontal reference line can be defined.

Objective: Our purpose was to suggest an operative concept in dealing with the female urinary stress incontinence in case of vaginal prolapse. We combined two operative procedures, Burch colposuspension and colpopexy after Williams and Richardson. In the first part, we introduce and explain the technique, in the second, we discuss the results of the clinical follow-up study. Methods and materials: Presently, accepted by most authors as the best method to correct urinary stress incontinence, we use the Burch colposuspension. This is combined by us with a technique for colpopexy developed by Williams and Richardson, which is particularly well known in the Anglo-American area. According to this method, we use two stripes of the rectus aponeurosis to bring the vagina into a slight anteversion. One of the effects resulting from this combination is that it supports the pull direction of the Burch colposuspension. All the alternative methods that fix the vagina to the sacrum or its ligaments, pull exactly in the opposite direction. The latter techniques are more widespread in Germany. Results: 103 women were treated. We offered them a clinical examination to assess the success of our operative concept. 62% agreed to join our study. Hence, we followed up 64 cases. After a mean observation time of 36 months we had 81.3% of the patients continent, but in urodynamics we found only 2 women with genuine stress incontinence. More than 95% showed a good morphological result with the vagina of sufficient length. A recurrence in descensus developed in 4.7%, all all of them posterior vaginal relaxation, all rectoceles, no enteroceles. On the other hand we found that colpopexy after Williams and Richardson is not complicated by severe dyspareunia that is often observed after sacropexy. None of our patients experienced dyspareunia or had decreased sexual activity. Conclusions : These two essential advantages, excellent synergistic support of the Burch colposuspension and lack of postoperative dyspareunia, leads us to recommend this procedure. The operative risk is relatively low. The high degree of good long term results confirmed that we were right in adopting this procedure. Nevertheless however, each of the two steps requires a careful and separate indication. In case of urinary incontinence, preoperative urodynamics is absolutely necessary, especially also under forensic aspects. This prevents unnecessary failures.

A theoretical study of storage, instability and rise of magnetic flux tubes in the outer convection zone of a cool star is presented. Special emphasis is laid on their emergence latitudes at the surface of magnetically active stars. We apply the ‘solar paradigm’ and assume toroidal magnetic flux tubes to be stored in force equilibrium within the overshoot layer underneath the convection zone. A non-axisymmetric (undulatory) instability leads to the formation of flux loops, which rise through the convection zone and emerge at the surface to form bipolar magnetic regions and starspots. Our approach combines the analytical determination of the linear stability properties of flux tubes with numerical simulations of the nonlinear evolution of the instability and the rise of magnetic flux tubes through the convection zone. It is found that for sufficiently rapidly rotating stars the magnetic flux emerges at high latitudes since the Coriolis force leads to a poleward deflection of rising flux loops. The latitude distribution of the emerging flux is determined for a number of stellar models along the evolutionary sequence of a star with one solar mass, from the pre-main sequence evolution up to the giant phase. Rapid rotation and deep convection zones favour flux emergence in high latitudes. Starspots right at the stellar (rotational) poles form either directly by flux eruption from small stellar cores (as for T Tauri stars or giants) or by a poleward slip of the sub-surface part of the flux tube after flux emergence in mid latitudes. The latter process explains the simultaneous existence of polar spots and spots at intermediate latitudes as observed on some stars.

1. 1. Functional and antiischaemic effects of monoacetyl-vitexinrhamnoside (AVR), a flavonoid with phosphodiesterase (PDE)-inhibitory properties contained in Crataegus species (Hawthorn, Rosaceae) were studied in several in-vitro models. 2. 2. In rabbit isolated femoral artery rings, AVR concentration-dependently reduced developed tension. Vasodilation by AVR was reduced after inhibiting EDRF formation by L-NG-nitro arginine. 3. 3. In spontaneously-beating Langendorff-guinea pig hearts, AVR concentration-dependently enhanced heart-rate, contractility, lusitropy and coronary flow. 4. 4. In isolated electrically-driven Langendorff-rabbit hearts, acute regional ischemia (MI) was induced by coronary artery occlusion and quantified from epicardial NADH-fluorescence photography. AVR (5 × 10−5 mol/l) induced a slight numerical increase of left ventricular pressure and coronary flow (p > 0.05). MI was reduced (p 5. 5. Monoacetyl-vitexinrhamnoside is an inodilator whose vasodilatory action may be mediated in part by EDRF in addition to PDE-inhibition. Monoacetyl-vitexinrhamnoside does possess marked antiischemic properties even in isolated hearts, suggesting an improvement of myocardial perfusion.

Magnetocardiography provides a new, alternative method for fetal surveillance. This method allows the registration of changes in the magnetic field produced by the fetal cardiac system. In comparison to fetal ECG, the fetal magnetocardiogram (fMCG) is not affected by intermediate tissue, in particular by the insulating effect of the vernix caseosa. Furthermore fMCG's with a good signal noise ratio can be obtained in the second trimester. A multichannel biomagnetometer allows the non-invasive measurement of the magnetic signals produced by the fetus. Examples of dta and evaluation techniques are given. Signal processing software allows the identification of all fetal beats in a data set, permitting the calculation of an averaged beat and the evaluation of signal morphology and cardiac time intervals. Furthermore it is possible to produce a beat to beat time series with high temporal resolution, making the evaluation of heart rate variability with measures from the time, frequency, and phase domain accessible. Particularly the latter are of interest in investigating changes in temporal complexity of the fetal cardiac system. Magnetocardiography thus holds the promise of improved antenatal surveillance as of the second trimester.

1. 1. The antiischemic properties of the flavonoids acetylvitexin-rhamnoside (AVR) and luteolin-7-glucoside-(LUT), combining phosphodiesterase (PDE)-inhibitory and antioxidant properties, were studied in comparison to amrinone (AMR) or superoxide dismutase (SOD). The effects of the new dihydropyridine-type calcium-agonist Bay T 5006 were studied in comparison to Bay K 8644. 2. 2. In isolated Langendorff-rabbit hearts perfused at constant pressure, acute regional ischemia (MI) was induced by coronary artery occlusion (CAO) and quantitated from epicardial NADH-fluorescence photography. Drugs were applied either before or after CAO (pre-treatment or treatment) to permit distinguishing the influence of functional and direct cytoprotective actions in the poorly collateralized rabbit hearts. 3. 3. SOD did not affect left ventricular pressure (LVP) or coronary flow (CF) and reduced MI only if applied before CAO. LVP and CF were enhanced by LUT or AMR but not by AVR. MI was reduced to a similar extent in hearts treated with either drug. Cardioprotection by LUT was not improved by starting drug application before CAO. 4. 4. Bay K 8644 reduced LVP and particularly CF, whereas Bay T 5006 did not affect functional parameters. MI was enlarged by Bay K 8644 and remained unaffected by treatment or pretreatment with Bay T 5006. 5. 5. AMR, LUT and AVR possess antiischemic properties related to an improvement of myocardial perfusion. Although oxygen free radicals contribute to ischemic tissue injury, as shown by the cardioprotective effectiveness of SOD, antioxidant properties of the flavonoids LUT and AVR do not seem to be relevant for the antiischemic effects. Our findings also give no evidence for antioxidant properties of dihydropyridines relevant for cardioprotection.

The oxidation of titanium enolates with tert-butylhydroperoxide has been investigated and the main reaction products, the corresponding α-hydroxyketones 7a-f, isolated. The highest diastereoselectivities (>95% de) were obtained, when titanium enolates of camphor 2d–6d were employed. For comparison, the oxidation of the enolates with dimethyldioxirane1 is discussed.

We consider the linear stability of a toroidal flux tube lying in the equatorial plane of a differentially rotating star and investigate its dependence on superadiabaticity, magnetic field strength, and gradient of angular velocity.

The combined action of the subadiabatic ambient stratification in the overshoot region below the convection zone and the inertial forces associated with the solar rotation is shown to lead to the suppression of the escape of magnetic flux in the form of toroidal flux tubes both toward the surface and toward higher latitudes. We show that a flux ring initially in thermal equilibrium with its environment and rotating with the ambient angular velocity moves radially and latitudinally towards an equilibrium configuration of lower internal temperature and larger internal rotation rate with respect to the surrounding, field-free gas. We conclude that flux rings with B≲ 105 G can be kept within the overshoot region if the superadiabaticity is sufficiently negative, i.e. δ = ▿ – ▿ad≲–10−5; below that field strength the poleward drift is also reduced to a latitudinal oscillation of moderate amplitude, δθ ≲ 20 deg. Flux rings with significantly larger field strength cannot be kept in the equatorial parts of the overshoot region: their equilibrium configuration is located at high latitudes far outside the solar activity belts and, at any rate, requires unrealistic values of δ.

The structure of solar surface magnetic fields, the way they erupt from the the convection zone below, and processes like flux expulsion and fragmentation instabilities support the view that magnetic flux in a stellar convection zone is in an intermittent, fragmented state which can be described as an ensemble of magnetic flux tubes. Depending on size and field strength, the dynamics of magnetic flux tubes can strongly differ from the behavior of a passive, diffuse field which is often assumed in conventional mean-field dynamo theory. Observed properties of active regions like emergence in low latitudes, Hale's polarity rules, tilt angles, and the process of sunspot formation from smaller fragments, together with theoretical considerations of the dynamics of buoyant flux tubes indicate that the magnetic structures which erupt in an emerging active region are not passive to convection and originate in a source region (presumably an overshoot layer below the convection zone proper) with a field strength of at least 105 G, far beyond the equipartition field strength with respect to convective flows. We discuss the consequences of such a situation for dynamo theory of the solar cycle and consider the possibility of dynamo models on the basis of flux tubes. A simple, illustrative example of a flux tube dynamo is presented.

The solar meridional flow is an important ingredient in Babcock-Leighton type models of the solar dynamo. Global variations of this flow have been suggested to explain the variations in the amplitudes and lengths of the activity cycles. Recently, cycle-related variations in the amplitude of the $P_2^1$ term in the Legendre decomposition of the observed meridional flow have been reported. The result is often interpreted in terms of an overall variation in the flow amplitude during the activity cycle. Using a semi-empirical model based upon the observed distribution of magnetic flux on the solar surface, we show that the reported variations of the $P_2^1$ term can be explained by the observed localized inflows into the active region belts. No variation of the overall meridional flow amplitude is required., Comment: Accepted in ApJ

For advanced therapies, the same basic principles for assessment apply as for any other biotechnological medicinal product. Nevertheless, the extent of data for quality, safety, and efficacy can be highly specific. Until recently, advanced therapies were not uniformly regulated across Europe, e.g., tissue engineered products were regulated either as medicinal products or medical devices. Thus, for some products no data from clinical studies are available, e.g., for autologous chondrocyte products. The draft guideline on Good Clinical Practice for clinical trials with advanced therapies describes specific additional requirements, e.g., ensuring traceability. Most clinical studies with advanced therapies in Germany are still in early phase I or II trials with highly divergent types of products and clinical indications. The Committee for Advanced Therapies (CAT) at the European Medicines Agency (EMEA) has been established to meet the scientific and regulatory challenges with advanced therapies.

In spite of declining smoking prevalence nothing is known about the motives of adolescents in Germany who abstain from smoking. If one knows what motives prevent youngsters from ever starting to smoke it would make it possible to adjust future preventive strategies that would reach the "hard core" of smoking adolescents. This study investigated the true motives of non-smokers and also focused on possible gender and social background as well as age differences in the structure of their motivation.In the SToP-Study ("Sources of Tobacco for Pupils" Study 2008) 780 pupils, of whom 709 were non-smokers from 32 school classes, grades 7-9, were interviewed about their smoking experience. In anonymized answers to the questions pupils wrote down their motives for being non-smokers. A total of 1,329 free text statements, some of them very elaborate, were categorized and evaluated in a qualitative analysis.The most important and frequently mentioned motives for not smoking were health related (78,1%). But the most significant health risks of tobacco consumption (cardiac and cerebrovascular disease, chronic obstructive pulmonary disease), except cancer risk, were hardly appreciated. Other important reasons for not smoking were aesthetic aversion (38.6%), lacking perception of a benefit (25.1%) and economic motives (20.9%). It was especially female grammar school pupils who most frequently expressed health and aesthetic reasons (such as disgust, smell and taste aversion, dental and finger discolorations) as motives for not smoking.Extrinsic reasons (legal restrictions, smoking bans imposed by parents and schools, age limits etc.) are not important reasons to abstain for young non-smokers. Specifically, arguments about health, participation in sports and being in good physical condition should be central to any advice given to young smokers within the setting of general medical practice.

Solar irradiance changes on a wide range of time scales and is a key driver of the Earth’s climate where secular variability in particular is relevant. This is, however, not well understood and our knowledge relies on reconstructions based on sunspot numbers and similar proxies.The prime candidate to produce secular variability is a change in the surface coverage of small‐scale magnetic elements. Direct observational determination of the flux emitted by these magnetic elements is difficult, especially as information covering a large spectral range is needed. Here we present a theoretical approach to this problem using intensity calculations from 3‐D simulations of solar magneto‐convection and compare these with the intensity calculations used in the successful semi‐empirical S ATIRE models at disk centre. Eventually, such a comparison should lead to the removal of the last free parameter from S ATIRE‐based irradiance reconstruction.

The state of theoretical description of small-scale concentrated magnetic fields in the solar photosphere (excluding oscillations and wave propagation) is reviewed with emphasis on work done since 1982. The processes which probably lead to the formation of strong fields (flux expulsion, convective collapse) are discussed in some detail and the present understanding of the subsequent (quasi-)equilibrium state is summarized. We consider in particular the magnetic and thermal structure of the basic magnetic flux concentrations (magnetic elements) and stress the importance of radiative transfer effects, e.g. the horizontal heat exchange with the surroundings and the effect of radiation from the hot bottom and walls on the upper layers. Velocity fields within and around magnetic flux concentrations are discussed with emphasis on shift and asymmetry of the observed StokesV-profiles which have recently been understood in terms of a downflow in the immediate vicinity outside magnetic structures. Reconnection and instabilities are considered as possible destruction processes for magnetic elements.

Background The historical aspects of the pathophysiology and treatment of Graves’ disease are briefly discussed in this paper. Materials and methods The three treatment modalities of Graves’ disease are anti-thyroid drug therapy, radioactive iodine therapy, and surgery. Although the majority of patients with Graves’ disease in the U.S. are treated with radioactive iodine, surgery still plays an important role when patients cannot tolerate anti-thyroid drug therapy, when medical treatment is rejected by patients, or when surgery is deemed the fastest and safest route in managing the patient. Conclusions The indications for surgical management of Graves’ disease are discussed with emphasis on available data supporting the extent of thyroid resection based on the incidences of hypothyroidism, recurrence of hyperthyroidism, recurrent laryngeal nerve injury and hypoparathyroidism.

The electrolytic deposition of Pd, Ti, and Ge is demonstrated. A process for depositing smooth surfaces of layers from 10 to 100 nm and thicker is described. Applications of this technology for Schottky and ohmic contacts are shown and the advantages to similar evaporated metallization schemes are listed.

Although positron emission tomography (PET) detects occult metastatic disease in approximately 20% of patients with isolated hepatic colorectal metastases, it is associated with false negative results in up to 16%. We hypothesized that patients with a poorer prognosis (as defined by clinical risk score [CRS]) would have a higher yield from PET. All patients with colorectal liver metastases who were imaged by means of PET between 1998 and 2002 were identified from a prospective PET database. All patients were assigned a CRS, with one point added for each of five preoperative factors (disease-free interval1 year, tumor size5 cm, tumor number1, carcinoembryonic antigen200, and node-positive primary lesion). A total of 85 PET scans were reviewed. In half the patients (53%), PET provided no additional information over conventional imaging. Occult extrahepatic disease was detected or questionable findings seen on conventional imaging were confirmed in 20% of PET scans, whereas PET readings were inaccurate in 27%. PET findings were correlated with CRS in a subset of 63 patients presenting with a first occurrence of hepatic colorectal metastases. Among patients with a CRS of 0, no patient had extrahepatic disease detected by PET and 57% had false positive readings, whereas among patients with a CRS of 1 or more, 14% were found to have additional disease that was detected only by PET, and there were no false positive readings (P0.001, Fisher's exact test). Patients with isolated hepatic colorectal metastases and a CRS of 0 should undergo conventional imaging alone prior to surgical exploration.