Long-Term Progression-Free Survival of a Pre-Treated Patient with Metastatic Colorectal Cancer Receiving Trifluridine/Tipiracil.

Trifluridine/tipiracil is approved for the use in later or last-line setting in previously treated metastatic colorectal cancer (mCRC) patients who progressed on standard anti-tumor drugs including 5-fluorouracil (5-FU), irinotecan, oxaliplatin, anti-VEGF and anti-EGFR antibodies, or who are not considered candidates for those standard therapies. In this report, we describe a 67-year-old male patient with KRAS-mutated mCRC and metachronous liver and lung metastasis who failed prior 5-FU- and irinotecan-containing regimens, but then showed long-term disease control for 31 months on single-agent trifluridine/tipiracil given as second-line treatment. According to our experience, trifluridine/tipiracil is a feasible and effective treatment option in earlier but not necessarily last-line therapy in mCRC patients who are not considered candidates for doublet or triplet chemotherapy. Besides its efficacy, it is associated with maintained quality of life and a manageable toxicity profile. Considering increasing age of mCRC patients and their wish for maintaining an independent lifestyle, further research on the use of trifluridine/tipiracil in earlier lines of systemic mCRC therapy is warranted.

Dynamic MR angiography in acute aortic dissection.

BACKGROUND: To evaluate the benefit (additional flow information), image quality, and diagnostic accuracy of a dynamic magnetic resonance angiography (MRA) combining high spatial and temporal resolution for the preinterventional assessment of acute aortic dissection. METHODS: Nineteen patients (12 men, 7 women; aged 32-78 years) with acute aortic dissection underwent contrast-enhanced four-dimensional (4D) MRA and 3D conventional high-resolution MRA (3D MRA) within one examination on a 1.5 Tesla MR system. Both MRA datasets for each patient were evaluated and compared for image quality and visualization of vascular details on a 5-point scale (5 = excellent image quality, 1 = nondiagnostic image quality). In addition, presence and relevance of additional hemodynamic information (flow direction and organ perfusion delay) gained by dynamic MRA were assessed. RESULTS: Conventional 3D MRA provided significantly higher values for image quality of the aorta and aortic side branches compared with dynamic MRA (aorta: 4.3 versus 3.3; P = 0.006 side branches: 4.2 versus 3.3; P = 0.02). However, in 10 of the 19 patients (53%) the additionally available information on flow dynamics due to dynamic MRA (e.g., delayed perfusion of parenchymal organs) led to a change in therapy planning and realization. CONCLUSION: Dynamic MRA is a technique that combines functional flow and morphological information. Thus, the combination of 3D and dynamic MRA provides all requested information for treatment planning in patients suffering from acute aortic dissection.

Follow-up of probably benign lesions in non-screening breast diagnostics.

PURPOSE: Our study addresses at the benefit of surveillance of probably benign lesions, detected outside mammographic screening, during a 3-year period. METHODS: 28,588 women (mean age 57 ± 12 years) were examined. Two independent radiologists read the mammogram as well as the supplemented ultrasound (in case of breast density ACR type 3 and 4). In the case of discordance a third expert considered whether further examination was indicated or not. RESULTS: 3,266 diagnostic procedures ended with BI-RADS 3 result and 2,512 (76.9 %) women underwent a follow-up examination. 295 (11.7 %) of them received assessment examination (imaging and/or biopsy) and 37 (12.5 %) (none of them palpable) ended with BI-RADS 6. This equals a tumor detection rate of 14.7/1,000. The ratio in situ:invasive was 7:10 (1:1.43) and the mean size was 11.1 ± 4.51 mm. In the total cohort, 536 carcinomas ended with BI-RADS 6 of them 17 % were in situ and 83 % were invasive breast cancers (ratio in situ:invasive 1:4.99), mean size was 13.8 ± 6.3 mm. The cancer detection ratio in these cases was 18.7/1,000. CONCLUSIONS: The amount of detected tumors at follow-up of women with preceding BI-RADS 3 equates the associated potential of malignancy.

Toward cardiovascular interventions guided by magnetic particle imaging: first instrument characterization.

Magnetic particle imaging has emerged as a new technique for the visualization and quantification of superparamagnetic iron oxide nanoparticles. It seems to be a very promising application for cardiovascular interventional radiology. A prerequisite for interventions is the artifact-free visualization of the required instruments and implants. Various commercially available catheters, guide wires, and a catheter experimentally coated with superparamagnetic iron oxide nanoparticles were tested regarding their signal characteristics using magnetic particle spectroscopy to evaluate their performance in magnetic particle imaging. The results indicate that signal-generating and non-signal-generating instruments can be distinguished. Furthermore, coating or loading non-signal-generating instruments with superparamagnetic iron oxide nanoparticles seems to be a promising approach, but optimized nanoparticles need yet to be developed.

Triple-TWIST MRA: high spatial and temporal resolution MR angiography of the entire peripheral vascular system using a time-resolved 4D MRA technique.

OBJECTIVES: Multi-station contrast-enhanced magnetic resonance angiography (MRA) is considered as the imaging investigation of first choice in patients suffering from peripheral arterial occlusive disease. In order to overcome venous overlay and to gain dynamic flow information as provided by digital subtraction angiography (DSA), we developed a triple injection protocol for high-resolution MRA of the entire peripheral vascular system, applying time-resolved (TR) four-dimensional (4D) MRA sequences. METHODS: Ten patients underwent three-station TR-MRA of the pelvis and lower extremities with DSA as reference standard. Both investigations were compared concerning stenosis on a segment-by-segment basis. Furthermore, 28 consecutive patients underwent the same MR-only imaging protocol. All images were evaluated concerning image quality (1 = non-diagnostic, 4 = excellent), venous overlay (from none up to substantial) and time to venous enhancement (very early/early/normal/late). RESULTS: Three-station TR-MRA proved feasible and was comparable with DSA in 282 vessel segments, with underestimation grade of stenosis in four segments and overestimation in four segments, respectively. In 32/38 patients no venous overlay was noted; in six patients there was mild venous overlay. Image quality was rated excellent or good in most cases. CONCLUSIONS: TR-MRA provides morphological and functional information without any timing issues due to optimal arterial enhancement at high spatial resolution without venous overlay.

Contrast-enhanced time-resolved 4D MRA of congenital heart and vessel anomalies: image quality and diagnostic value compared with 3D MRA.

OBJECTIVES: To evaluate time-resolved interleaved stochastic trajectories (TWIST) contrast-enhanced 4D magnetic resonance angiography (MRA) and compare it with 3D FLASH MRA in patients with congenital heart and vessel anomalies. METHODS: Twenty-six patients with congenital heart and vessel anomalies underwent contrast-enhanced MRA with both 3D FLASH and 4D TWIST MRA. Images were subjectively evaluated regarding total image quality, artefacts, diagnostic value and added diagnostic value of 4D dynamic imaging. Quantitative comparison included signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and vessel sharpness measurements. RESULTS: Three-dimensional FLASH MRA was judged to be significantly better in terms of image quality (4.0 ± 0.6 vs 3.4 ± 0.6, P < 0.05) and artefacts (3.8 ± 0.4 vs 3.3 ± 0.5, P < 0.05); no difference in diagnostic value was found (4.2 ± 0.4 vs 4.0 ± 0.4); important additional functional information was found in 21/26 patients. SNR and CNR were higher in the pulmonary trunk in 4D TWIST, but slightly higher in the systemic arteries in 3D FLASH. No difference in vessel sharpness delineation was found. CONCLUSIONS: Although image quality was inferior compared with 3D FLASH MRA, 4D TWIST MRA yields robust images and added diagnostic value through dynamic acquisition was found. Thus, 4D TWIST MRA is an attractive alternative to 3D FLASH MRA. KEY POINTS: • New magnetic resonance angiography (MRA) techniques are increasingly introduced for congenital cardiovascular problems. • Time-resolved angiography with interleaved stochastic trajectories (TWIST) is an example. • Four-dimensional TWIST MRA provided inferior image quality compared to 3D FLASH MRA but without significant difference in vessel sharpness. • Four-dimensional TWIST MRA gave added diagnostic value.

Outcome and management of invasive candidiasis following oesophageal perforation.

The regular colonisation of the oesophagus with a Candida species can, after oesophageal perforation, result in a contamination of the mediastinum and the pleura with a Candida species. A patient cohort of 80 patients with oesophageal perforation between 1986 and 2010 was analysed retrospectively. The most common sources with positive results for Candida were mediastinal biopsies and broncho-alveolar secretions. Candida species were detected in 30% of the patients. The mortality rate was 41% in patients with positive microbiology results for Candida, whereas it was 23% in the remaining patient cohort. This difference did not reach statistical significance (P = 0.124). Mortality associated with oesophageal perforation was attributed mainly to septic complications, such as mediastinitis and severe pneumonia. During the study period we observed a shift towards non-albicans species that were less susceptible or resistant to fluconazole. In selected patients with risk factors as immunosuppression, granulocytopenia and long-term intensive-care treatment together with the finding of Candida, an antimycotic therapy should be started. A surgical approach offers the possibility to obtain deep tissue biopsies. The antimycotic therapy should start with an echinocandin, as the resistance to fluconazole is growing and to cover non-albicans Candida species, too.

Magnetic particle imaging: visualization of instruments for cardiovascular intervention.

PURPOSE: To evaluate the feasibility of different approaches of instrument visualization for cardiovascular interventions guided by using magnetic particle imaging (MPI). MATERIALS AND METHODS: Two balloon (percutaneous transluminal angioplasty) catheters were used. The balloon was filled either with diluted superparamagnetic iron oxide (SPIO) ferucarbotran (25 mmol of iron per liter) or with sodium chloride. Both catheters were inserted into a vessel phantom that was filled oppositional to the balloon content with sodium chloride or diluted SPIO (25 mmol of iron per liter). In addition, the administration of a 1.4-mL bolus of pure SPIO (500 mmol of iron per liter) followed by 5 mL of sodium chloride through a SPIO-labeled balloon catheter into the sodium chloride-filled vessel phantom was recorded. Images were recorded by using a preclinical MPI demonstrator. All images were acquired by using a field of view of 3.6 × 3.6 × 2.0 cm. RESULTS: By using MPI, both balloon catheters could be visualized with high temporal (21.54 msec per image) and sufficient spatial (≤ 3 mm) resolution without any motion artifacts. The movement through the field of view, the inflation and deflation of the balloon, and the application of the SPIO bolus were visualized at a rate of 46 three-dimensional data sets per second. CONCLUSION: Visualization of SPIO-labeled instruments for cardiovascular intervention at high temporal resolution as well as monitoring the application of a SPIO-based tracer by using labeled instruments is feasible. Further work is necessary to evaluate different labeling approaches for diagnostic catheters and guidewires and to demonstrate their navigation in the vascular system after administration of contrast material. SUPPLEMENTAL MATERIAL: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120424/-/DC1.

Benefits of the quality assured double and arbitration reading of mammograms in the early diagnosis of breast cancer in symptomatic women.

OBJECTIVES: To address the benefits of double and arbitration reading regarding tumour detection rates, percentage of in situ tumours, and number (of patients) needed to send for expert reading (number needed to treat; NNT) for one additional tumour finding. METHODS: QuaMaDi is a quality assured breast cancer diagnosis programme; with two-view mammography (craniocaudal, mediolateral oblique) and, in case of breast density ACR 3 or 4, routine ultrasound imaging; and with independent double reading of all images. A consecutive sample of symptomatic women, i.e. women at risk for breast cancer, women aged 70 and above, and/or women with preceding BI-RADS III findings, was analysed. RESULTS: 28,558 mammograms were performed (mean age of women: 57.3 [standard deviation: 12.3] years). Discordant findings were present in 3,837 double readings and were sent for arbitration reading. After histopathological assessment, 52 carcinomas were found (thereof 32% in situ). These carcinomas accounted for 1.8 tumours per 1,000 examinations in the total cohort and increased the tumour detection rate up to 16.4/1,000. The NNT in discordant cases was 74. CONCLUSION: Double and arbitration reading appears to be a useful tool to ensure the quality of early detection of breast lesions in symptomatic women during indication-based, standardised mammography. KEY POINTS: • Quality assured breast cancer diagnosis is feasible outside organised screening structures. • Double and arbitration reading is beneficial for populations ineligible for screening. • Double and arbitration reading increases the tumour detection rate. • Double and arbitration reading increases the percentage of in situ cancers.

Diagnostic accuracy of contrast-enhanced FDG-PET/CT in primary staging of cutaneous malignant melanoma.

PURPOSE: To evaluate the diagnostic accuracy of contrast-enhanced FDG-PET/CT (ce-PET/CT), PET-only, and CT-only in patients with newly diagnosed and resected cutaneous malignant melanoma. METHODS: A final group of 56 patients (mean age 62 years, range 23-86 years; 29 women, 27 men) were staged with ce-PET/CT after resection of the primary tumour. Histopathology as well as clinical follow-up (mean 780 days, range 102-1,390 days) served as the standards of reference. Differences between the staging modalities were tested for statistical significance with McNemar's test. RESULTS: All imaging procedures provided low sensitivities in the detection of lymph nodes (sensitivity N-stage: PET/CT and PET-only 38.5%; CT-only 23.1%) and distant metastases (sensitivity M-stage: PET/CT 41.7%, PET-only 33.3%, CT-only 25.0%) in initial staging after resection of the primary tumour. No statistically significant differences were detected between the imaging procedures (p > 0.05). PET/CT resulted in an alteration in further treatment in two patients compared to PET-only and in four patients compared to CT-only. CONCLUSION: All imaging modalities had a low sensitivity on initial staging of patients with malignant melanoma. Thus, close patient follow-up must be considered mandatory.

Feasibility of whole-body MR with T2- and T1-weighted real-time steady-state free precession sequences during continuous table movement to depict metastases.

The purpose of the study was to prospectively evaluate a whole-body magnetic resonance (MR) imaging protocol to help depict metastases by using unenhanced T2-weighted and contrast material-enhanced T1-weighted real-time sequences during continuous table movement. The study was conducted after approval of the local institutional review board and written informed consent were obtained. In 11 patients with positron emission tomographic (PET) scans positive for tumors and known metastases, whole-body MR imaging, including T2- and T1-weighted sequences, was performed before and after contrast material administration. A high-precision laser position sensor was used to register the table position for off-line multiplanar reformations of the acquired transverse whole-body data sets. Seventy-three of 75 metastases detected by using PET/computed tomography were correctly diagnosed by using MR imaging. Metastases with a diameter exceeding 5 mm could be visualized in all anatomic regions.

Significance of an additional unenhanced scan in computed tomography angiography of patients with suspected acute aortic syndrome.

AIM: To assess potential benefits of an additional unenhanced acquisition in computed tomography angiography (CTA) in patients with suspected acute aortic syndrome (AAS). METHODS: A total of 103 aortic CTA (non-electrocardiography-gated, 128 slices) performed due to suspected AAS were retrospectively evaluated for acute aortic dissection (AAD), intramural hematoma (IMH), or penetrating aortic ulcer (PAU). Spiral CTA protocol consisted of an unenhanced acquisition and an arterial phase. If AAS was detected, a venous phase (delay, 90 s) was added. Images were evaluated for the presence and extent of AAD, IMH, PAU, and related complications. The diagnostic benefit of the unenhanced acquisition was evaluated concerning detection of IMH. RESULTS: Fifty-six (30% women; mean age, 67 years; median, 68 years) of the screened individuals had AAD or IMH. A triphasic CT scan was conducted in 76.8% (n = 43). 56% of the detected AAD were classified as Stanford type A, 44% as Stanford type B. 53.8% of the detected IMH were classified as Stanford type A, 46.2% as Stanford type B. There was no significant difference in the involvement of the ascending aorta between AAD and IMH (P = 1.0) or in the average age between AAD and IMH (P = 0.548), between Stanford type A and Stanford type B in general (P = 0.650) and between Stanford type A and Stanford type B within the entities of AAD and IMH (AAD: P = 0.785; IMH: P = 0.146). Only the unenhanced acquisitions showed a significant density difference between the adjacent lumen and the IMH (P = 0.035). Subadventitial hematoma involving the pulmonary trunk was present in 5 patients (16%) with Stanford A AAD. The difference between the median radiation exposure of a triphasic (2737 mGy*cm) compared to a biphasic CT scan (2135 mGy*cm) was not significant (P = 0.135). CONCLUSION: IMH is a common and difficult to detect entity of AAS. An additional unenhanced acquisition within an aortic CTA protocol facilitates the detection of IMH.

Comparison of the Revenue Situation in Interventional Radiology Based on the Example of Peripheral Artery Disease in the Case of a DRG Payment System and Various Internal Treatment Charges.

PURPOSE: Calculation of process-orientated costs for inpatient endovascular treatment of peripheral artery disease (PAD) from an interventional radiology (IR) perspective. Comparison of revenue situations in consideration of different ways to calculate internal treatment charges (ITCs) and diagnosis-related groups (DRG) for an independent IR department. MATERIALS AND METHODS: Costs (personnel, operating, material, and indirect costs) for endovascular treatment of PAD patients in an inpatient setting were calculated on a full cost basis. These costs were compared to the revenue situation for IR for five different scenarios: 1) IR receives the total DRG amount. IR receives the following DRG shares using ITCs based on InEK shares for 2) "Radiology" cost center type, 3) "OP" cost center type, 4) "Radiology" and "OP" cost center type, and 5) based on DKG-NT (scale of charges of the German Hospital Society). RESULTS: 78 patients (mean age: 68.6 ±â€Š11.4y) with the following DRGs were evaluated: F59A (n = 6), F59B (n = 14), F59C (n = 20) and F59 D (n = 38). The length of stay for these DRG groups was 15.8 ±â€Š12.1, 9.4 ±â€Š7.8, 2.8 ±â€Š3.7 and 3.4 ±â€Š6.5 days Material costs represented the bulk of all costs, especially if new and complex endovascular procedures were performed. Revenues for neither InEK shares nor ITCs based on DKG-NT were high enough to cover material costs. Contribution margins for the five scenarios were 1 = €â€Š1,539.29, 2 = €â€Š-1,775.31, 3 = €â€Š-2,579.41, 4 = €â€Š-963.43, 5 = €â€Š-2,687.22 in F59A, 1 = €â€Š-792.67, 2 = €â€Š-2,685.00, 3 = €â€Š-2,600.81, 4 = €â€Š-1,618.94, 5 = €â€Š-3,060.03 in F59B, 1 = €â€Š-879.87, 2 = €â€Š-2,633.14, 3 = €â€Š-3,001.07, 4 = €â€Š-1,952.33, 5 = €â€Š-3,136.24 in F59C and 1 = €â€Š703.65, 2 = €â€Š-106.35, 3 = €â€Š-773.86, 4 = €â€Š205.14, 5 = €â€Š-647.22 in F59 D. InEK shares return on average €â€Š150 - 500 more than ITCs based on the DKG-NT catalog. CONCLUSION: In this study positive contribution margins were seen only if IR receives the complete DRG amount. InEK shares do not cover incurred costs, with material costs representing the main part of treatment costs. Internal treatment charges based on the DKG-NT catalog provide the worst cost coverage. KEY POINTS: · Internal treatment charges based on the DKG-NT catalog provide the worst cost coverage for interventional radiology at our university hospital.. · Shares from the InEK matrix such as the cost center "radiology" or "OP" as revenue for IR are not sufficient to cover incurred costs. A positive contribution margin is achieved only in the case of a compensation method in which IR receives the total DRG amount.. CITATION FORMAT: · Vogt FM, Hunold P, Haegele J et al. Comparison of the Revenue Situation in Interventional Radiology Based on the Example of Peripheral Artery Disease in the Case of a DRG Payment System and Various Internal Treatment Charges. Fortschr Röntgenstr 2017; 190: 348 - 357.

Morphologic and functional changes in nontumorous liver tissue after radiofrequency ablation in an in vivo model: comparison of 18F-FDG PET/CT, MRI, ultrasound, and CT.

UNLABELLED: Rimlike contrast enhancement on morphologic imaging and increased tracer uptake on (18)F-FDG PET in the periphery of the necrosis can hamper differentiation of residual tumor from regenerative tissue after radiofrequency ablation of liver lesions. This study used MRI, CT, ultrasound, and (18)F-FDG PET/CT to assess the typical appearance of lesions in nontumorous animal liver tissue after radiofrequency ablation. METHODS: Lesions were created by radiofrequency ablation of normal liver parenchyma in 21 minipigs. Follow-up was performed by 3 contrast-enhanced morphologic modalities-MRI, CT, and ultrasound-and by (18)F-FDG PET/CT immediately, 3 and 10 d, and 1, 2, 3, and 6 mo after radiofrequency ablation. Images were evaluated qualitatively for areas of increased enhancement and regions of elevated tracer uptake. Furthermore, all images were assessed quantitatively by determination of ratios comparing enhancement/tracer uptake in the periphery of the necrosis with enhancement/tracer uptake in normal liver parenchyma. Imaging findings were compared with histopathology findings. RESULTS: Immediately after radiofrequency ablation, no increase in (18)F-FDG uptake was visible, whereas elevated enhancement was noticed in the periphery of the necrosis on all morphologic imaging procedures. At further follow-up, an area of rimlike increase in (18)F-FDG uptake surrounding the necrosis was detected on PET/CT. The rimlike pattern of increased enhancement in the arterial phase was present for all liver lesions on CT, MRI, and ultrasound, especially between day 3 and month 1 after the radiofrequency ablation. Both elevated glucose metabolism and enhancement persisted for 6 mo postinterventionally. Histologic examination showed a hemorrhagic border converting into a regeneration capsule. CONCLUSION: If performed immediately after radiofrequency ablation, (18)F-FDG PET/CT probably has benefits over those of morphologic imaging procedures when assessing liver tissue for residual tumor. Later follow-up may be hampered by visualization of peripheral hyperperfusion and tissue regeneration. Further studies on a patient population are essential.

Magnetic Particle Imaging (MPI): Experimental Quantification of Vascular Stenosis Using Stationary Stenosis Phantoms.

Magnetic Particle Imaging (MPI) is able to provide high temporal and good spatial resolution, high signal-to-noise ratio and sensitivity. Furthermore, it is a truly quantitative method as its signal strength is proportional to the concentration of its tracer, superparamagnetic iron oxide nanoparticles (SPIOs). Because of that, MPI is proposed to be a promising future method for cardiovascular imaging. Here, an interesting application may be the quantification of vascular pathologies like stenosis by utilizing the proportionality of the SPIO concentration and the MPI signal strength. In this study, the feasibility of MPI based stenosis quantification is evaluated based on this application scenario. Nine different stenosis phantoms with a normal diameter of 10 mm each and different stenoses of 1-9 mm and ten reference phantoms with a straight diameter of 1-10 mm were filled with a 1% Resovist dilution and measured in a preclinical MPI-demonstrator. The MPI signal intensities of the reference phantoms were compared to each other and the change of signal intensity within each stenosis phantom was used to calculate the degree of stenosis. These values were then compared to the known diameters of each phantom. As a second measurement, the 5 mm stenosis phantom was used for a serial dilution measurement down to a Resovist dilution of 1:3200 (0.031%), which is lower than a first pass blood concentration of a Resovist bolus in the peripheral arteries of an average adult human of at least about 1:1000. The correlation of the stenosis values based on MPI signal intensity measurements and based on the known diameters showed a very good agreement, proving the high precision of quantitative MPI in this regard.

The brain renin-angiotensin system plays a crucial role in regulating body weight in diet-induced obesity in rats.

BACKGROUND AND PURPOSE: Reduced weight gain after treatment with AT1 receptor antagonists may involve a brain-related mechanism. Here, we investigated the role of the brain renin-angiotensin system on weight regulation and food behaviour, with or without additional treatment with telmisartan. METHODS: Transgenic rats with a brain-specific deficiency in angiotensinogen (TGR(ASrAOGEN)) and the corresponding wild-type, Sprague Dawley (SD) rats were fed (3 months) with a high-calorie cafeteria diet (CD) or standard chow. SD and TGR(ASrAOGEN) rats on the CD diet were also treated with telmisartan (8 mg·kg(-1) ·d(-1) , 3 months). RESULTS: Compared with SD rats, TGR(ASrAOGEN) rats (i) had lower weights during chow feeding, (ii) did not become obese during CD feeding, (iii) had normal baseline leptin plasma concentrations independent of the feeding regimen, whereas plasma leptin of SD rats was increased due to CD, (iv) showed a reduced energy intake, (v) had a higher, strain-dependent energy expenditure, which is additionally enhanced during CD feeding, (vi) had enhanced mRNA levels of pro-opiomelanocortin and (vii) showed improved glucose control. Weight gain and energy intake in rats fed the CD diet were markedly reduced by telmisartan in SD rats but only to a minor extent in TGR(ASrAOGEN) rats. CONCLUSIONS: The brain renin-angiotensin system affects body weight regulation, feeding behaviour and metabolic disorders. When angiotensin II levels are low in brain, rats are protected from developing diet-induced obesity and obesity-related metabolic impairments. We further suggest that telmisartan at least partly lowers body weight via a CNS-driven mechanism.

Multi-color magnetic particle imaging for cardiovascular interventions.

Magnetic particle imaging (MPI) uses magnetic fields to visualize the spatial distribution of superparamagnetic iron oxide nanoparticles (SPIOs). Guidance of cardiovascular interventions is seen as one possible application of MPI. To safely guide interventions, the vessel lumen as well as all required interventional devices have to be visualized and be discernible from each other. Until now, different tracer concentrations were used for discerning devices from blood in MPI, because only one type of SPIO could be imaged at a time. Recently, it was shown for 3D MPI that it is possible to separate different signal sources in one volume of interest, i.e. to visualize and discern different SPIOs or different binding states of the same SPIO. The approach was termed multi-color MPI. In this work, the use of multi-color MPI for differentiation of a SPIO coated guide wire (Terumo Radifocus 0.035″) from the lumen of a vessel phantom filled with diluted Resovist is demonstrated. This is achieved by recording dedicated system functions of the coating material containing solid Resovist and of liquid Resovist, which allows separation of their respective signal in the image reconstruction process. Assigning a color to the different signal sources results in a differentiation of guide wire and vessel phantom lumen into colored images.

Magnetic Particle Imaging: A Resovist Based Marking Technology for Guide Wires and Catheters for Vascular Interventions.

Magnetic particle imaging (MPI) is able to provide high temporal and good spatial resolution, high signal to noise ratio and sensitivity. Furthermore, it is a truly quantitative method as its signal strength is proportional to the concentration of its tracer, superparamagnetic iron oxide nanoparticles (SPIOs), over a wide range practically relevant concentrations. Thus, MPI is proposed as a promising future method for guidance of vascular interventions. To implement this, devices such as guide wires and catheters have to be discernible in MPI, which can be achieved by coating already commercially available devices with SPIOs. In this proof of principle study the feasibility of that approach is demonstrated. First, a Ferucarbotran-based SPIO-varnish was developed by embedding Ferucarbotran into an organic based solvent. Subsequently, the biocompatible varnish was applied to a commercially available guidewire and diagnostic catheter for vascular interventional purposes. In an interventional setting using a vessel phantom, the coating proved to be mechanically and chemically stable and thin enough to ensure normal handling as with uncoated devices. The devices were visualized in 3D on a preclinical MPI demonstrator using a system function based image reconstruction process. The system function was acquired with a probe of the dried varnish prior to the measurements. The devices were visualized with a very high temporal resolution and a simple catheter/guide wire maneuver was demonstrated.

Assessment of liver tissue after radiofrequency ablation: findings with different imaging procedures.

UNLABELLED: Our goal was to assess the typical appearance of normal liver tissue immediately after radiofrequency ablation (RF-ablation) when imaged with contrast-enhanced ultrasound, CT, MRI, 18F-FDG PET, and PET/CT. METHODS: Nineteen RF-ablation sessions were performed on nontumorous liver tissue of 10 Göttingen Mini Pigs. CT, ultrasound, MRI, 18F-FDG PET, and PET/CT were performed immediately after the intervention. All imaging procedures were evaluated qualitatively for areas of increased contrast enhancement (morphologic imaging) and regions of elevated tracer uptake (functional imaging). Images were assessed quantitatively by determination of ratios (r(p/p)) comparing contrast enhancement/tracer uptake in the periphery of the necrosis with contrast enhancement/tracer uptake of normal liver parenchyma. RESULTS: On morphologic imaging, an increase in contrast enhancement surrounding the ablative necrosis was detected in all lesions. Quantification of this area of increased contrast enhancement revealed ratios of r(p/p) = 1.57 +/- 0.2 for CT and r(p/p) = 1.57 +/- 0.19 for MRI. On PET and PET/CT, homogeneous tracer utilization was found surrounding all lesions. There were no areas of a focal or rim-like increase in glucose metabolism. The ratio r(p/p) was found to be 1.05 +/- 0.08 for functional data. Histologic examination revealed pooling of blood in the sinusoids of the lesion's periphery that was caused by outflow obstruction due to the central necrosis. CONCLUSION: On morphologic imaging, a rim-like increase of contrast enhancement was found immediately after RF-ablation resembling peripheral hyperperfusion. This area of contrast enhancement may hamper detection of residual tumor. On the basis of homogeneous tracer distribution surrounding the area of necrosis, PET and PET/CT may serve for early assessment of patients after RF-ablation.

Whole-body MRI for staging patients with head and neck squamous cell carcinoma.

CONCLUSIONS: Whole-body MRI is feasible for the tumor staging of patients with malignant head and neck tumors and appears to be a quick, reliable and proven alternative in general and for patients with contraindications to CT. This examination minimizes the logistical effort required compared to multimodality strategies. Its economic impact remains to be determined. OBJECTIVE: To assess the performance of whole-body MRI for staging patients with squamous cell carcinoma of the head and neck region. MATERIAL AND METHODS: This was a randomized, prospective clinical study. For tumor staging, 21 patients (mean age 56.7 years; range 43-80 years) with advanced malignant head and neck tumors underwent whole-body MRI in addition to routinely performed imaging investigations, including sonography, chest X-ray, CT of the head, neck and thorax and endoscopy. All investigations were accomplished within a period of 10+/-3 days in a random order. A randomized, blinded, consensus assessment of all the whole-body MRI examinations was performed by two radiologists. The localization and extent of the primary tumor and metastases were documented for whole-body MRI and compared to the standard of reference (all other imaging modalities as well as histology). Point estimates of the diagnostic accuracy of whole-body MRI were calculated. RESULTS: In accordance with the standard of reference, the overall TNM category was correctly determined with whole-body MRI in all 21 patients. However, four patients were classified as having carcinoma of unknown primary, as the primary tumor was not found with any imaging modality. Two patients had mediastinal, pulmonary and hepatic metastases.