Assessment of metastatic colorectal cancer with hybrid imaging: comparison of reading performance using different combinations of anatomical and functional imaging techniques in PET/MRI and PET/CT in a short case series.

PURPOSE: The purpose was to investigate the diagnostic performance of different combinations of anatomical and functional imaging techniques in PET/MRI and PET/CT for the evaluation of metastatic colorectal cancer lesions. METHODS: Image data of 15 colorectal cancer patients (FDG-PET/CT and subsequent FDG-PET/MRI) were retrospectively evaluated by two readers in five reading sessions: MRI (morphology) alone, MRI/diffusion-weighted MRI (DWI), MRI/PET, MRI/DWI/PET; and PET/CT. Diagnostic performance of lesion detection with each combination was assessed in general and organ-based. The reference standard was given by histology and/or follow-up imaging. Separate analysis of mucinous tumours was performed. RESULTS: One hundred and eighty lesions (110 malignant) were evaluated (intestine n = 6, liver n = 37, lymph nodes n = 55, lung n = 4, and peritoneal n = 74). The overall lesion-based diagnostic accuracy was 0.46 for MRI, 0.47 for MRI/DWI, 0.57 for MRI/PET, 0.69 for MRI/DWI/PET and 0.66 for PET/CT. In the organ-based assessment, MRI/DWI/PET showed the highest accuracy for liver metastases (0.74), a comparable accuracy to PET/CT in peritoneal lesions (0.55), and in lymph node metastases (0.84). The accuracy in mucinous tumour lesions was limited in all modalities (MRI/DWI/PET = 0.52). CONCLUSIONS: PET/MRI including DWI is comparable to PET/CT in the evaluation of colorectal cancer metastases, with a markedly higher accuracy when using combined imaging data than the modalities separately. Further improvement is needed in the imaging of peritoneal carcinomatosis and mucinous tumours.

Recurrent pyogenic cholangitis as a differential diagnosis in biliary tract diseases.

Recurrent Pyogenic Cholangitis (RPC) or Primary Hepatolithiasis is a common disease of the biliary tract in Asia, whereas it is usually not seen in Europeans. With increasing global mobility, the disease will be encountered in Europe more frequently, too. It should therefore be considered as a differential diagnosis in patients from endemic countries with recurrent symptoms of cholestasis/cholangitis and bile duct dilations, strictures and hepatolithiasis. In this case report, we present the history of a 37-year old patient from Sri Lanka and describe typical aspects of RPC. The patient presented at our hospital with scleral jaundice and pruritus. In the past she had been treated for septic cholangitis. Diagnosis in our patient was made after laboratory tests, MRT/MRCP and ERC. She was treated interventionally by ERC and is now monitored on a regular basis.

[Mesothelial proliferation in rectal cancer]. / Mesotheliale Proliferate bei Rektumkarzinom.

In an epiphrenic lymph node of a 55 years old female patient who underwent surgical resection of a rectal adenocarcinoma epitheloid proliferations with papillary and solid growth pattern were seen additional to a metastasis of the carcinoma. Adjacent vessels contained similar infiltrates. Immunohistochemically a co-expression of pan-keratin, calretinin and WT1 was seen, suggestive for a diagnosis of a metastasis of a malignant mesothelioma. However, radiologic examination yielded no morphologic correlate to this suspicion. Further immunohistochemical work-up showed positivity for desmin, negativity for EMA, GLUT1, p53 and a low ki67-fraction of 2-3 %. Therefore, a final diagnosis of benign mesothelial proliferations disseminated into the lymph node and the adjacent vessels was made.

Staging of neuroendocrine tumours: comparison of [68Ga]DOTATOC multiphase PET/CT and whole-body MRI.

PURPOSE: In patients with a neuroendocrine tumour (NET), the extent of disease strongly influences the outcome and multidisciplinary therapeutic management. Thus, systematic analysis of the diagnostic performance of the existing staging modalities is necessary. The aim of this study was to compare the diagnostic performance of 2 whole-body imaging modalities, [(68)Ga]DOTATOC positron emission tomography (PET)/computed tomography (CT) and magnetic resonance imaging (MRI) in patients with NET with regard to possible impact on treatment decisions. MATERIALS AND METHODS: [(68)Ga]DOTATOC-PET/CT and whole-body magnetic resonance imaging (wbMRI) were performed on 51 patients (25 females, 26 males, mean age 57 years) with histologically proven NET and suspicion of metastatic spread within a mean interval of 2.4 days (range 0-28 days). PET/CT was performed after intravenous administration of 150 MBq [(68)Ga]DOTATOC. The CT protocol comprised multiphase contrast-enhanced imaging. The MRI protocol consisted of standard sequences before and after intravenous contrast administration at 1.5 T. Each modality (PET, CT, PET/CT, wbMRI) was evaluated independently by 2 experienced readers. Consensus decision based on correlation of all imaging data, histologic and surgical findings and clinical follow-up was established as the standard of reference. Lesion-based and patient-based analysis was performed. Detection rates and accuracy were compared using the McNemar test. P values <0.05 were considered significant. The impact of whole-body imaging on the treatment decision was evaluated by the interdisciplinary tumour board of our institution. RESULTS: 593 metastatic lesions were detected in 41 of 51 (80%) patients with NET (lung 54, liver 266, bone 131, lymph node 99, other 43). One hundred and twenty PET-negative lesions were detected by CT or MRI. Of all 593 lesions detected, PET identified 381 (64%) true-positive lesions, CT 482 (81%), PET/CT 545 (92%) and wbMRI 540 (91%). Comparison of lesion-based detection rates between PET/CT and wbMRI revealed significantly higher sensitivity of PET/CT for metastatic lymph nodes (100% vs 73%; P < 0.0001) and pulmonary lesions (100% vs 87%; P = 0.0233), whereas wbMRI had significantly higher detection rates for liver (99% vs 92%; P < 0.0001) and bone lesions (96% vs 82%; P < 0.0001). Of all 593 lesions, 22 were found only in PET, 11 only in CT and 47 only in wbMRI. The patient-based overall assessment of the metastatic status of the patient showed comparable sensitivity of PET/CT and MRI with slightly higher accuracy of PET/CT. Patient-based analysis of metastatic organ involvement revealed significantly higher accuracy of PET/CT for bone and lymph node metastases (100% vs 88%; P = 0.0412 and 98% vs 78%; P = 0.0044) and for the overall comparison (99% vs 89%; P < 0.0001). The imaging results influenced the treatment decision in 30 patients (59%) with comparable information from PET/CT and wbMRI in 30 patients, additional relevant information from PET/CT in 16 patients and from wbMRI in 7 patients. CONCLUSION: PET/CT and wbMRI showed comparable overall lesion-based detection rates for metastatic involvement in NET but significantly differed in organ-based detection rates with superiority of PET/CT for lymph node and pulmonary lesions and of wbMRI for liver and bone metastases. Patient-based analysis revealed superiority of PET/CT for NET staging. Individual treatment strategies benefit from complementary information from PET/CT and MRI.

Thyroid perfusion imaging as a diagnostic tool in Graves' disease--arterial spin labeling magnetic resonance imaging vs. colour-coded Doppler ultrasound.

PURPOSE: Though increased thyroid perfusion assessed by colour-coded Doppler ultrasound (CDUS) is characteristic of Graves' disease (GD), sometimes perfusion assessment by CDUS is not possible. In these cases, arterial spin labelling (ASL), a novel magnetic resonance imaging (MRI) technique allowing non-invasive thyroid perfusion quantification, may have additional diagnostic value. We aimed to evaluate the potential of ASL-MRI for assessment of increased blood perfusion in patients with GD compared to CDUS. MATERIALS AND METHODS: Thyroid perfusion was measured by CDUS (volume flow rate calculated from pulsed wave Doppler signals and vessel diameter) and ASL-MRI at 1.5 T in 7 patients with GD and 10 healthy controls. RESULTS: In patients with GD, average perfusion in both thyroid lobes was markedly increased compared to controls. Both techniques applied for volume related perfusion as well as absolute volume flow in thyroid feeding vessels provided similar results (all p=0.0008). Using a cut-off value of 22 ml/min for the volume flow rate assessed by CDUS in the four feeding vessels allowed discrimination between patients with GD and controls in all cases. After adjusting thyroid perfusion for the differences in organ volume, both CDUS and ASL revealed also complete discrimination between health and disease. CONCLUSION: Thyroid perfusion measurement by ASL-MRI reliably discriminate GD from normal thyroid glands. In patients in whom thyroid arteries cannot be depicted by CDUS for technical or anatomical reasons, ASL-MRI may have additional diagnostic value.

Simultaneous PET/MR imaging in a human brain PET/MR system in 50 patients--current state of image quality.

OBJECTIVES: The present work illustrates the current state of image quality and diagnostic accuracy in a new hybrid BrainPET/MR. MATERIALS AND METHODS: 50 patients with intracranial masses, head and upper neck tumors or neurodegenerative diseases were examined with a hybrid BrainPET/MR consisting of a conventional 3T MR system and an MR-compatible PET insert. Directly before PET/MR, all patients underwent a PET/CT examination with either [18F]-FDG, [11C]-methionine or [68Ga]-DOTATOC. In addition to anatomical MR scans, functional sequences were performed including diffusion tensor imaging (DTI), arterial spin labeling (ASL) and proton-spectroscopy. Image quality score of MR imaging was evaluated using a 4-point-scale. PET data quality was assessed by evaluating FDG-uptake and tumor delineation with [11C]-methionine and [68Ga]-DOTATOC. FDG uptake quantification accuracy was evaluated by means of ROI analysis (right and left frontal and temporo-occipital lobes). The asymmetry indices and ratios between frontal and occipital ROIs were compared. RESULTS: In 45/50 patients, PET/MR examination was successful. Visual analysis revealed a diagnostic image quality of anatomical MR imaging (mean quality score T2 FSE: 1.27±0.54; FLAIR: 1.38±0.61). ASL and proton-spectroscopy was possible in all cases. In DTI, dental artifacts lead to one non-diagnostic dataset (mean quality score DTI: 1.32±0.69; ASL: 1.10±0.31). PET datasets of PET/MR and PET/CT offered comparable tumor delineation with [11C]-methionine; additional lesions were found in 2/8 [(68)Ga]-DOTATOC-PET in the PET/MR. Mean asymmetry index revealed a high accordance between PET/MR and PET/CT (1.5±2.2% vs. 0.9±3.6%; mean ratio (frontal/parieto-occipital) 0.93±0.08 vs. 0.96±0.05), respectively. CONCLUSIONS: The hybrid BrainPET/MR allows for molecular, anatomical and functional imaging with uncompromised MR image quality and a high accordance of PET results between PET/MR and PET/CT. These results justify the application of this technique in further clinical studies and may contribute to the transfer into whole-body PET/MR systems.

Depiction of variants of the portal confluence venous system using multidetector row CT: analysis of 916 cases.

PURPOSE: Detailed knowledge of the venous mesenteric system is important for gastrointestinal surgery, particularly for transplantation planning and surgery and for the comprehension of perioperative complications that may influence patient outcome. Data about the mesenteric venous anatomy in the literature varies substantially. The purpose of this study was to categorize venous mesenteric variants and to determine their incidence. MATERIALS AND METHODS: We included 916 patients requiring diagnostic abdominal CT in the portal venous phase. The mesenteric vein anatomy was categorized as follows: 1. the inferior mesenteric vein (IMV) enters the splenic vein (SV); 2. the IMV enters into the angle of the confluence of the SV and superior mesenteric vein (SMV) forming the portal vein (PV); 3. the IMV enters the SMV; 4. seven rare variants. We measured the diameters of the veins and distances from the confluence to the IMV origins. RESULTS: The frequency of variants was: 1. 37.6%, 2. 28.8%; 3. 19.2%. The rare variants totaled 14.4%. The average vessel diameters measured in cm: PV 1.48; SV 1.02; SMV 1.2; IMV 0.5. The mean IMV entering distances were 1.66 cm in variant 1 and 0.75 cm in variant 3. CONCLUSION: The three common variants (1, 2 and 3) are the most relevant ones. 14.4% of patients had different anatomic variants. The variability of the mesenteric venous system was higher than previously published. Knowledge of rare variants is important to avoid complications in abdominal surgery.

Antimicrobial efficiency of titanium dioxide-coated surfaces.

AIMS: Development and evaluation of an antimicrobially active titanium dioxide coating. METHODS AND RESULTS: For this purpose, titanium dioxide coatings were applied to glass slides by using a sol-gel method and then exposed to a light source. The antimicrobial efficiency was determined by a count reduction test for selected test strains (Aspergillus niger, Bacillus atrophaeus, Kocuria rhizophila), which were homogenously sprayed onto surface. The bacterial count of K. rhizophila was reduced by up to 3.3 log(10) on titanium dioxide samples within 4 h of UV-A light exposure. Experiments with spore formers did not lead to any significant log reduction. A further aspect of this work was to evaluate the effect of selected parameters (relative humidity, inoculation density, radiation intensity) on the antimicrobial efficiency to gain knowledge for further optimization procedures. At a high relative humidity (85% r.h.), increased inactivation was observed for K. rhizophila (up to 5.2 log(10)). Furthermore, a dependency of the antimicrobial effect on the radiation intensity and the inoculation density was identified. CONCLUSIONS: Antimicrobial surfaces and coatings based on titanium dioxide have the potential to effectively inactivate vegetative micro-organisms. SIGNIFICANCE AND IMPACT OF THE STUDY: Knowledge about the antimicrobial efficiency of titanium dioxide was gained. This is a prerequisite for industrial applications to improve hygiene, food quality and safety.

High cardiorespiratory fitness is an independent predictor of the reduction in liver fat during a lifestyle intervention in non-alcoholic fatty liver disease.

OBJECTIVE: Lifestyle intervention with diet modification and increase in physical activity is effective for reducing hepatic steatosis in patients with non-alcoholic fatty liver disease (NAFLD). However, for a similar weight loss, there is a large variability in the change in liver fat. We hypothesised that cardiorespiratory fitness may predict the response to the intervention. DESIGN: Longitudinal study with increase in physical activity and diet modification. SETTING: University teaching hospital. PATIENTS: 50 adults with NAFLD and 120 controls at risk for metabolic diseases. MAIN OUTCOME MEASURES: Total-, subcutaneous abdominal- and visceral adipose tissue by magnetic resonance tomography, liver fat by 1HMR spectroscopy and cardiorespiratory fitness (VO(2,max)) by a maximal cycle exercise test at baseline and after 9 months of follow-up. RESULTS: In all subjects total-, subcutaneous abdominal- and visceral adipose tissue decreased and fitness increased (all p<0.0001) during the intervention. The most pronounced changes were found for liver fat (-31%, p<0.0001). Among the parameters predicting the change in liver fat, fitness at baseline emerged as the strongest factor, independently of total- and visceral adipose tissue as well as exercise intensity (p = 0.005). In the group of subjects with NAFLD at baseline, a resolution of NAFLD was found in 20 individuals. For 1 standard deviation increase in VO(2,max) at baseline the odds ratio for resolution of NAFLD was 2.79 (95% confidence interval, 1.43-6.33). CONCLUSIONS: Cardiorespiratory fitness, independently of total adiposity, body fat distribution and exercise intensity, determines liver fat content in humans, suggesting that fitness and liver fat are causally related to each other. Moreover, measurement of fitness at baseline predicts the effectiveness of a lifestyle intervention in reducing hepatic steatosis in patients with NAFLD.

[Internally cooled bipolar radiofrequency ablation: is a lower power output more effective?]. / Intern gekühlte bipolare Radiofrequenzablation: Ist eine niedrige Leistung effektiver?

PURPOSE: Evaluation of bipolar radiofrequency (RF) ablation using internally cooled electrodes in an ex-vivo experiment. MATERIALS AND METHODS: Bipolar RF ablations (n = 154) were performed in ex-vivo bovine liver. Both electrodes with a total length of the active tip of 4 cm were located on the same shaft of an internally cooled applicator. The power output was systematically varied between 20 and 100 watts (W). The energy application was continuous or modulated depending on the tissue resistance. In relationship to the maximum power output, the volume of coagulation was assessed. RESULTS: In continuous energy application the induced volume of coagulation was increased at lower power outputs up to 33.7 cm (3) (20 watts). Parallel to an increased volume of coagulation, the required duration of energy application was increased up to a maximum of 51.6 minutes. Modulation of the power output as a function of the tissue resistance enabled application of a wide range of power outputs (40 - 75 watts) leading to a comparable extent of coagulation with a maximum of 14.9 cm (3) (10 min.), 16.8 cm (3) (15 min.), and 19.1 cm (3) (20 min.). CONCLUSION: Continuous application of RF energy leads to an inverse relationship between volume of coagulation and power output. Modulation of the power output as a function of the tissue resistance enables application of a wider range of power outputs compared to continuous application of RF energy.

Magnetic resonance imaging for hepatic radiofrequency ablation.

Image-guided radiofrequency (RF) ablation is a minimally invasive therapy option in the treatment of primary and secondary hepatic malignancies. Magnetic resonance (MR) imaging offers an accurate pre-interventional imaging having important impact on patient selection and planning of the ablation procedure. Peri-interventional imaging is used for targeting, monitoring, and controlling of the ablation procedure. Due to a high soft-tissue contrast offering delineation of tumor tissue and the surrounding anatomy, coupled with multiplanar capabilities, MR imaging is an advantageous targeting technique compared with ultrasonography (US) or computed tomography (CT). MR imaging is sensitive to thermal effects enabling a monitoring of ablation therapy subsequently being supportive to control the ablation procedure. Therefore, MR imaging can fulfil the conditions for overlapping ablations by enabling a precise repositioning of the MR compatible RF applicator if required. Thus, the probability of achieving complete coagulation in larger tumors within a single therapy session is potentially increased. A monitoring of thermal effects is moreover essential in order to prevent unintended tissue damage from critical structures in the surrounding of the target tissue. Post-interventional imaging is performed to assess treatment response after RF ablation and has prognostic impact, as an early detection of treatment failure, e.g. residual tumor tissue, enables immediate therapy. Nevertheless, differential diagnostic difficulties arise from benign periablational enhancement which may cover tumor tissue. Hence, further evaluation and improvement in the assessment of treatment response is essential.

Identification of drought-sensitive beech ecotypes by physiological parameters.

• The effects of drought on European beech (Fagus sylvatica) were assessed in a pot experiment under controlled conditions. • Plants from 11 autochthonous provenances originating from regions in Germany, which differed in annual precipitation, were exposed to a 3-wk drought period in a glasshouse after the first stage of shoot growth had been completed. • Drought reduced the water content to 97% of control in leaves and axes and to 92% in the roots. A strong reduction of predawn water potential in roots and shoots, as well as on transpiration rate, was found. In the roots, the effect on water potential was the same for all provenances, but differences were observed in the shoot water potential. Leaf concentrations of abscisic acid (ABA), proline and sucrose increased in the drought-treated plants compared with the controls. • Two extreme clusters from opposite climatic sites were identified by cluster analysis. A drought-sensitive cluster, originating from regions with high annual precipitation, had low water potential and transpiration rates, as well as high concentrations of fructose, ABA and proline after drought. Water potential and transpiration rates were less affected by drought in the other cluster, which comprised two provenances of relatively dry habitats, and concentrations of hexose, ABA and proline were low.

Foliar antioxidant status of adult Mediterranean oak species (Quercus ilex L. and Q. pubescens Willd.) exposed to permanent CO2-enrichment and to seasonal water stress.

Foliar antioxidants were measured in adult individuals of holm oak (Quercus ilex L.) and white oak (Q. pubescens Willd.) growing in the field either within the vicinity of natural CO2 springs or at a nearby control site under ambient CO2, which had been previously exposed to either daily irrigation or no irrigation. In oak trees permanently exposed to elevated CO2 the activities of antioxidant enzymes tended to be lower and the ascorbate pool was larger and more in reduced form, suggesting an attenuation of the oxidative risk in the CO2-enriched trees. In the enriched individuals of both species. the imposition of water shortage significantly increased the size of the glutathione pool and the total superoxide dismutase activity in a species-specific manner. Moreover, water-stressed trees exposed to elevated CO2 tended to have higher catalase and ascorbate peroxidase activities than water-stressed control trees. Such changes may reflect the need for an enhanced compensatory effort when trees acclimated to elevated CO2 are exposed to oxidative stress-promoting environmental factors, such as water shortage.