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A 79-year-old woman with a newly detected oval circumscribed lump in subcutaneous location on mammography and ultrasound turned out to be a Schwannoma after ultrasound-guided core needle biopsy. A 72-year-old woman with breast cancer in medical history demonstrated a new axillary mass in follow up, initially regarded as a lymph node metastasis. Core needle biopsy did not lead to a sufficient diagnosis. Pathologic examination after intraoperative sampling revealed a Schwannoma. These 2 case reports illustrate the importance of diagnostic imaging and remind to include Schwannomas in the differential diagnosis of breast and axillary masses.

Purpose To determine the magnetic resonance (MR) sequences best suited for the assessment of ablation zones after radiofrequency ablation (RFA). Methods Three percutaneous MR-guided RFA of the liver were performed on three swine. Four pre-contrast and two hepatobiliary post-contrast sequences were obtained after ablation. Tissue samples were extracted and stained for nicotinamide adenine dinucleotide diaphorase hydride (NADH) and with hematoxylin and eosin. Post-ablation MR images and NADH slides were segmented to determine the total ablation zone, their Dice similarity coefficient (DSC), and the contrast-to-noise ratio (CNR) of the visible ablation boundary to normal liver tissue. Results Two distinct layers were combined to determine the ablation zone: an inner layer of coagulation necrosis and an outer layer defined as the peripheral transition zone. Corresponding zones could be found in the MR images as well. Compared to histology, the total area of the MR ablation zone was significantly smaller on the pre-contrast T1 images (p p = 0.025). No significant difference in size of the ablation zone depiction could be found between histology, post-contrast T1 volumetric interpolated breath-hold examination (VIBE), and post-contrast T1 3D Turboflash (TFL) as well as T2 SPACE images. All sequences but the pre-contrast T1 VIBE sequence showed a DSC above 80% and a high CNR. Conclusions Post-contrast T1 3DTFL performs best when assessing ablation zones after RFA. Since the sequence requires a long acquisition time, T1 VIBE post-contrast offers the best compromise between acquisition time and estimation accuracy.

Background Vascular cooling effects are a well-known source for tumor recurrence in thermal in situ ablation techniques for hepatic malignancies. Microwave ablation (MWA) is an ablation technique to be considered in the treatment of malignant liver tumors. The impact of vascular cooling in MWA is still controversial. Purpose To evaluate the influence of different intrahepatic vessel types, vessel sizes, and vessel-to-antenna-distances on MWA geometry in vivo. Material and Methods Five MWAs (902–928 MHz) were performed with an energy input of 24.0 kJ in three porcine livers in vivo. MWA lesions were cut into 2-mm slices. The minimum and maximum radius of the ablation area was measured for each slice. Distances were measured from ablation center toward all adjacent hepatic vessels with a diameter of ≥1 mm and within a perimeter of 20 mm around the antenna. The respective vascular cooling effect relative to the maximum ablation radius was calculated. Results In total, 707 vessels (489 veins, 218 portal fields) were detected; 370 (76%) hepatic veins and 185 (85%) portal fields caused a cooling effect. Portal fields resulted in higher cooling effects (37%) than hepatic veins (26%, P Conclusion Hepatic vessels influenced MWA zones and caused a distinct cooling effect. Portal fields resulted in more pronounced cooling effect than hepatic veins. No cooling effect was observed around vessels situated within the central white zone.

Background The present paper aims to assess the lower threshold of vascular flow rate on the heat sink effect in bipolar radiofrequency ablation (RFA) ex vivo. Methods Glass tubes (vessels) of 3.4 mm inner diameter were introduced in parallel to bipolar RFA applicators into porcine liver ex vivo. Vessels were perfused with flow rates of 0 to 1,500 ml/min. RFA (30 W power, 15 kJ energy input) was carried out at room temperature and 37°C. Heat sink effects were assessed in RFA cross sections by the decrease in ablation radius, area and by a high-resolution sector planimetry. Results Flow rates of 1 ml/min already caused a significant cooling effect (P ≤ 0.001). The heat sink effect reached a maximum at 10 ml/min (18.4 mm/s) and remained stable for flow rates up to 1,500 ml/min. Conclusions Minimal vascular flows of ≥1 ml/min cause a significant heat sink effect in hepatic RFA ex vivo. A lower limit for volumetric flow rate was not found. The maximum of the heat sink effect was reached at a flow rate of 10 ml/min and remained stable for flow rates up to 1,500 ml/min. Hepatic inflow occlusion should be considered in RFA close to hepatic vessels.

Background It is well known that physical abuse of children all too often escapes detection. Fractures are among the potential consequences of physical abuse but are also com- mon in childhood because of accidents. A question frequently addressed to the Medical Child Protection Hotline (Medizini- sche Kinderschutzhotline) is how fractures due to abuse can be distinguished from accidental fractures. Methods This review is based on pertinent publications retrieved by a search in PubMed and in the Cochrane Data- base, as well as on the authors' experience in a pediatric emergency department with ca. 29 000 consultations per year and in a child protection outpatient clinic with ca. 100 consultations per year. Results Fractures due to abuse are especially common among infants; their incidence is estimated at 56.8/100 000 among infants less than six months old and 39.8/100 000 among infants aged 6 to 11 months. In consideration of the age of the child, the type of fracture, the history, and other factors, a high probability of abuse can be suspected in many cases, so that further measures can be initiated. Conclusion All physicians involved in the care of children (even if only occasionally) should be aware of the major indicators of likely physical abuse and of the available oppor- tunities for counseling and intervention. Failures to diagnose child abuse are associated with high rates of recurrence and mortality.

Purpose: To find out if the hepatic transit time (HTT) shortening, which was already proven in patients with liver metastases by other modalities, can also be detected with MRI. Materials and Methods: The Patient group consisted of 20 subjects with liver metastases from colorectal cancer and the control group of 21 healthy subjects. Baseline and post contrast images were acquired before and after administration of Gd-BOPTA, using a T1-weighted bolus test sequence. Arrival times (AT) of the contrast agent for the aorta, the hepatic artery, the portal vein and one hepatic vein were determined. Based on arrival time measurements HTT were calculated. Results: All analyses showed significantly shorter HTT in patients with metastases compared with healthy volunteers (P < 0.05). There were no false positives using a threshold of 10.4 s for arterial to venous HTT. For aortal to venous and portal to venous HTT a threshold of 12.5 s and 4 s was calculated, respectively. No significant correlation between HTT and involved liver segments, overall volume of metastases or subject age was found. Conclusion: We conclude that HTT measurements using contrast enhanced MRI with Gd-BOPTA can detect hemodynamic changes due to metastatic liver disease from colorectal cancer. J. Magn. Reson. Imaging 2012; 36:1389–1394. © 2012 Wiley Periodicals, Inc.

To determine the colonic mural enhancement in a rat model of inflammatory bowel disease (IBD) using gadofluorine M- and diethylenetriamine pentaacetic acid (Gd-DTPA)-enhanced magnetic resonance (MR) imaging, and to correlate the degree of enhancement with the histopathologic severity of the disease.: This study was approved by our hospital's institutional animal care and use committee. A total of 44 rats with 2 grades (mild, n = 17; and severe, n = 27) of dinitrobenzene sulfonic acid (DNBS)-induced IBD and 13 rats without IBD, were examined using a 2.4-T, small animal MR scanner. T2- and T1-weighted MR images were acquired, and sequential T1-weighted MR imaging was then performed immediately and again 15, 45, 60, and 90 minutes, and 24 hours after intravenous -injection of either gadofluorine M- or Gd-DTPA (0.1 mmol Gd/kg body weight). The signal-to-noise ratios and enhancement ratios (ER) of the colon wall were measured. For paired and group comparisons of the histopathology and MR imaging data, the Wilcoxon- and the Mann-Whitney U tests were used, and the multifactorial analysis of variance test was used to compare the time courses of the ERs.: Gadofluorine M injection resulted in significant differences in the ER of noninflamed, mildly inflamed, and severely inflamed colon wall at any time up to 24 hours after contrast injection (ER at 24 hours 2.0 ± 1.2; 10.1 ± 4.3; and 49.7 ± 10.8, respectively; P0.01). After Gd-DTPA injection, significant differences were observed in the ER of inflamed and noninflamed bowel at 15, 45, and 60 minutes (P0.01); however, no significant differences in mildly and severely inflamed bowel were observed at any time. In contrast to Gadofluorine M, there was no prolonged contrast enhancement in the inflamed colon wall after intravenous injection of Gd-DTPA (ER at 24 hours 1.6 ± 1.3; 3.4 ± 2.7; and 3.3 ± 1.6, respectively; n.s.).: Gadofluorine M-enhanced MR imaging shows a higher correlation of the wall enhancement and histopathology grading in an IBD rat model than does Gd-DTPA-enhanced imaging.

Background The prevalence of thyroid nodules ranges between 2% and 60% depending on the population studied. However, minimally invasive procedures like radiofrequency ablation (rfA) are increasingly used to treat tumors of parenchymatous organs, and seem to be suitable for singular thyroid nodules as well. Their successful clinical application depends on the induction of sufficiently large lesions and a knowledge of the energy parameters required for complete thermal ablation. The aim of this study was to establish a dose-response relationship for rfA of thyroid nodules. Material and Methods Thermal lesions were induced in healthy porcine thyroid glands ex vivo ( n = 110) and in vivo ( n = 10) using a bipolar radiofrequency system; rf was applied in a power range of 10–20 watts. During the ablation, continuous temperature measurement at a distance of 5 and 10 mm from the applicator was performed. The transversal and axial lesion diameters were measured, and the volume was calculated. Furthermore, enzyme histochemical analysis of the thyroid tissue was performed. Results The inducible lesion volumes were between 0.91 ± 0.71cm 3 at 20W and 2.80 ± 0.85cm 3 at 14W. The maximum temperatures after rf ablation were between 44.0 ± 9.7°C and 61.6 ± 13.9°C at a distance of 5mm and between 30.0 ± 8.6°C and 53.5 ± 8.6°C at a distance of 10mm from the applicator. The histochemical analysis demonstrates a complete loss of nicotinamide adenine dinucleotide phosphate-oxidase (NADPH) dehydrogenase activity in thermal lesions as a sign of irreversible cell damage. Conclusion This study is the first to demonstrate a dose-response relationship for rfA of thyroid tissue. rfA is suitable for singular thyroid nodules and induces reproducible, clinically relevant lesions with irreversible cell damage in an appropriate application time.

Background Sigmoid diverticulitis (SD) is common in the West; its incidence is increasing as the average age of the population increases. The aim of this study was to assess the clinical outcomes of patients with acute SD and to determine whether emergency operation was associated more often with previous episodes of acute diverticulitis. Methods All consecutive patients admitted for acute SD were recruited prospectively over an 11-year period from January 1998 to December 2008. Multiple logistic regression was used to identify risk factors for free perforation. Results We included 934 patients (490 men and 444 women; median age, 59.2 years): 450 (48.2%) presented for their first SD episode and 484 (51.8%) had a prior history of SD. Free perforation occurred in 152 patients: during the first episode of SD in 114 patients (25.3%), during the second in 29 (12.7%), during the third in 8 (5.9%), and during the fifth in 1 patient (0.9%; P 5 previous episodes of SD had free perforation. All 152 patients with free perforation required emergent operative intervention. After initial conservative therapy in 782 patients, 82 required early elective operative intervention owing to exacerbation of infection under antibiotic treatment. Late elective colectomy was performed in 299 patients during the inflammation-free interval, and operative intervention was recommended in 345 patients owing to complicated diverticulitis. Uncomplicated SD in 56 patients was managed conservatively. Comorbidity (>1 disorder) and the first episode of SD were identified as risk factors for free perforation on multiple logistic regression. Conclusion The risk of free perforation in acute SD decreases with the number of previous episodes of SD. The first episode thus is the most dangerous for a free perforation. The indication for colectomy should not be made based on the potential risk of free perforation.

In situ ablation is increasingly being used for the treatment of liver malignancies. The application of these techniques is limited by the lack of a precise prediction of the destruction volume. This holds especially true in anatomically difficult situations, such as metastases in the vicinity of larger liver vessels. We developed a three-dimensional (3D) planning system for laser-induced thermotherapy (LITT) of liver tumors. The aim of the study was to validate the system for calculation of the destruction volume.LITT (28 W, 20 min) was performed in close contact to major hepatic vessels in six pigs. After explantation of the liver, the coagulation area was documented. The liver and its vascular structures were segmented from a pre-interventional CT scan. Therapy planning was carried out including the cooling effect of adjacent liver vessels. The lesions in vivo and the simulated lesions were compared with a morphometric analysis.The volume of lesions in vivo was 6,568.3 ± 3,245.9 mm(3), which was not different to the simulation result of 6,935.2 ± 2,538.5 mm(3) (P = 0.937). The morphometric analysis showed a sensitivity of the system of 0.896 ± 0.093 (correct prediction of destructed tissue). The specificity was 0.858 ± 0.090 (correct prediction of vital tissue).A 3D computer planning system for the prediction of thermal lesions in LITT was developed. The calculation of the directional cooling effect of intrahepatic vessels is possible for the first time. The morphometric analysis showed a good correlation under clinical conditions. The pre-therapeutic calculation of the ablation zone might be a valuable tool for procedure planning.

Purpose To evaluate if erythromycin compromises liver-specific enhancement of gadoxetic acid; both compounds competing in organic anion transporting peptides (OATP) -mediated hepatocytic uptake. Materials and Methods The study was approved by institutional review board. Twelve healthy subjects (nine men, three woman; mean age, 38.7 years) were examined twice by MR imaging with prior administration of NaCl solution (placebo) or 1000 mg of erythromycin following a randomized sequence. Gadoxetic acid (0.025 mmol/kg body weight) was administered 15 min after the end of infusions. Pre- and 20 min postcontrast two-dimensional gradient-recalled-echo sequences were acquired. Relative enhancements of liver parenchyma and ratio of means were calculated from signal intensity measurements. Plasma levels of gadoxetic acid and erythromycin were determined and given in geometric means and coefficients of variation (CV). Results Concentration of erythromycin directly after end of infusion was 13.9 mg/L (CV 14.9%). Gadolinium plasma concentrations 5 min after gadoxetic acid administration were 138.7 μmol/L (CV 20.4%) after erythromycin infusion and 129.6 μmol/L (CV 22.8%) after placebo. Mean relative enhancements of liver parenchyma were 88.1 (SD 24.9%) after erythromycin infusion and 92.6 (SD 17.9%) after placebo. Ratio of relative enhancements was 0.951 (95% confidence interval, 0.833; 1.061; statistically not significant). Conclusion Coadministration of erythromycin has no effect on gadoxetic acid enhanced liver MR imaging. J. Magn. Reson. Imaging 2011;33:409–416. © 2011 Wiley-Liss, Inc.

Ein 26-jahriger Patient stellte sich in der Klinik zur Abklarung einer seit 6 Monaten bestehenden chronischen Diarrho mit Oberbauchschmerzen vor. Die Anamnese ergab den endoskopischen Vorbefund einer leichten erosiven Duodenitis mit konsekutiver Einleitung einer Protonenpumpeninhibitortherapie. Korperliche Untersuchung und Basislabor blieben ohne richtungweisenden Befund. Die weiterfuhrende Diagnostik mit erneuter Endoskopie, Schnittbildgebung und Bestimmung der neuroendokrinen Marker ermoglichte ebenfalls keine atiologische Zuordnung der Beschwerden. Daraufhin wurde ein Auslassversuch der Protonenpumpeninhibitortherapie durchgefuhrt. Dies fuhrte zum erstmaligen endoskopischen Nachweis von duodenalen Ulzera bei einer deutlich progredienten Grundsymptomatik. Insgesamt ergab sich somit trotz negativer Labormarker eine fur ein Gastrinom typische Symptomkonstellation. In der weiteren Abklarung konnten die Diagnose eines Gastrinoms gestellt und der Tumor lokalisiert werden. Nach erfolgreicher Therapie mit einer pyloruserhaltenden Pankreatikoduodenektomie war der Patient im weiteren Verlauf beschwerdefrei. Die Untersuchung auf eine neuroendokrine Genese kann bei einer chronischen Diarrho Teil der systematischen differentialdiagnostischen Abklarung sein. Bei klinischem Verdacht sollte hierbei der seltene Fall eines gastrinnegativen Gastrinoms bedacht und diagnostisch abgeklart werden.

The indications for prophylactic surgery for phlegmonous and covered perforated type of acute sigmoid diverticulitis (SD) are currently matters of debate, and a more conservative approach has been advocated. However, it has not yet been clarified to what extent CT findings indicative of acute SD correlate with histological findings, and it is still uncertain how these findings change in the time interval between initial antibiotic treatment and late elective surgery. The aim of this study was to record time-course changes of inflammation in phlegmonous and abscess-forming diverticulitis after conservative treatment in order to check the indication for surgery. This study included all patients who underwent surgery for CT morphologically phlegmonous and covered perforated SD from January 2002 to June 2007. Two groups were formed to record time-course changes: early elective surgery (7–10 days after antibiotic treatment) and late elective surgery (4–6 weeks after conservative treatment). Exclusion criteria were emergency interventions, free perforations (Hinchey III and IV), recurrent inflammations, and contrast allergy. The extent of the inflammation recorded preoperatively by CT scan was compared with histological findings. A total of 257 patients (142 male and 115 female; mean age, 56.6 years) underwent surgery (116 early elective and 141 late elective) for phlegmonous and covered perforated SD. Phlegmonous SD was seen in 127 cases and covered perforated SD in 130 cases. In the phlegmonous type of SD, early surgery led to conformity with the preoperative stage in 56%, to more extensive findings in 11%, and to subsided inflammation in 33%. Late surgery led to conformity in 0% and to signs of subsided inflammation in 100%. In the covered perforated type of SD, early surgery led to conformity in 90%, to subsided inflammation in 10%, and to milder manifestation in 0%. In contrast, late surgery here led to conformity in 26% of the cases and to subsided inflammation in 74%. Considerable histological changes can be detected under conservative therapy. The acute inflammation subsides under antibiotic therapy as awaited. It must be clarified whether the phlegmonous form of SD should, in principal, be regarded as an indication for surgery, since it shows early and nearly complete regression of the inflammation. Otherwise, the covered perforated type of SD still shows marked inflammatory changes after conservative therapy in a high percentage of patients and should thus preferably be treated by surgery. However, the clinical appearance of the patient with sigmoid diverticulitis still remains the most important part of decision making.

Interspecies difference is an important issue in toxicology research. We compared the potential in vitro metabolism of human, porcine and rat hepatocytes over 2 weeks in culture in an organotypical culture model which reflects the in vivo situation. All three species show similar LDH-rates. Albumin measurements showed that rat cells are about twice as active as human and porcine hepatocytes. The ethoxyresorufin-O-deethylase (EROD) activity of the rat hepatocytes is with about 14 microU/10(6)cells distinctly higher than those of porcine and human cells (1.8 and 0.5 microU/10(6)cells respectively), furthermore, the activity of the rat EROD increases slightly during the prolonged time in culture, whereas those of porcine and human enzymes slightly decrease. Concerning ethoxycoumarin-O-deethylase (ECOD), the enzyme activities are found to be in three different ranges where rat cells show the highest activity with 66 microU/10(6)cells, porcine hepatocytes exhibit an activity of about 23 microU/10(6)cells, and human activity is lowest with 0.7 microU/10(6)cells. All three species show a similar decreasing trend of ECOD during the period of study. Regarding the biotransformation of testosterone, human and porcine liver cells form three major metabolites whereas rat cells form a mixture of all measured metabolites. Hence, in vitro metabolism using porcine hepatocytes would be much more scientific sense than one using rat hepatocytes since the metabolic pathways are much closer to human metabolism.

To prospectively evaluate diagnostic accuracy of first pass and combined first pass and steady state high-spatial-resolution whole-body magnetic resonance (MR) angiography with a blood pool contrast agent for quantification of arterial stenosis in different vascular territories.After Institutional Review Board approval and informed consent, 50 patients with known 50% or greater stenosis in at least one vascular territory; as shown by the standard-of-reference (14 digital subtraction angiographies, 4 computed tomographies, 32 ultrasound examinations), were included. The patients underwent MR angiography at 1.5 Tesla, using a standardized nonbody-weight-adapted i.v. bolus injection of 11 mL gadofosveset trisodium. First pass imaging with 4 different table positions in a whole-body MR scanner (MAGNETOM Avanto, Siemens Healthcare), using individual circulation time determined by a test bolus, was performed. Steady state imaging was performed using an isometric spatial resolution of 1.0 mm. Image quality was rated. Each vascular segment in MR angiography was evaluated by 2 independent and blinded reviewers and the stenosis degree was compared with the preferred standard-of-reference, using a 5-point scale. Differences between first pass and combined MR angiography were assessed with a 95% confidence interval (CI) by applying the adjusted modified chi(2) test. Changes in therapy based on the whole-body examination strategy were evaluated.The number of nondiagnostic territories was 24 of 197 (12.2%) for first pass MR angiography and decreased to 3 of 197 (1.5%) after addition of steady state MR angiography. The diagnostic accuracy for quantification of arterial stenosis in combined MR angiography (94.7%; 95% CI: 92.4-97.1) was superior to first pass MR angiography (81.7%; 95% CI: 73.7-89.8; statistically significant). Patient management was changed in 12 of 49 patients, in 7 of 12 patients the change was applied to an additional lesion detected by the whole-body examination strategy.The quantification and detection of arterial stenosis is improved by the steady state high-resolution gadofosveset trisodium-enhanced MR angiography. Additional lesions detected by whole-body examination strategy or differences in stenosis quantification may lead to changes in therapy.

OBJECTIVES To quantitatively and qualitatively characterize the MR findings of inflammatory bowel disease in a rat model after i.v. injection of the reticuloendothelial system cell specific ultrasmall iron oxide SHU 555 C. MATERIALS AND METHODS Colitis was induced in 15 rats using dinitrobenzene sulfonic acid instillation. Five rats served as controls. T1- and T2-weighted spin-echo- and T2*-weighted gradient-echo-sequences were acquired at 2.4 Tesla before and immediately, 15, 45, 60, and 90 minutes, and 24 hours after i.v.-injection of SHU 555 C (0.1 mmol Fe/kg). MR images were evaluated quantitatively regarding thickness and signal-to-noise ratio (SNR) of the bowel wall and qualitatively regarding overall bowel wall signal intensity and the occurrence of bowel wall ulcerations. MR findings were correlated to histology. RESULTS The inflamed bowel wall was significantly thicker than the noninflamed bowel wall and 90 minutes after contrast injection it showed a significant reduction of SNR in T1- (94 +/- 27 vs. 61 +/- 29; P < 0.01), T2- (67 +/- 26 vs. 28 +/- 17; P < 0.05), and T2*- (92 +/- 57 vs. 10 +/- 7; P < 0.05) weighted images as compared with unenhanced images. At 24 hours, the respective SNR values remained significantly reduced. The signal loss was homogeneous in 12 and focal in 3 of the 15 rats with colitis. Nine rats showed colonic wall ulcerations. In all but one animal (missed focal ulceration) MR findings correlated to the histologic findings. CONCLUSIONS SHU 555 C leads to a significant signal intensity loss of the inflamed bowel wall in T1-, T2- and T2*-weighted images. SHU 555 C enhanced MRI findings correlate well with histologic findings.

The aim of this study was to prospectively evaluate the needle visualization and placement error and use of an electromagnetic field-based tracking navigation device for puncture procedures based on C-arm CT (CACT) images. A commercially available navigation device was mounted on an angiographic X-ray system setup for CACT. After the target was defined, needle placement was performed under real-time visualization of the virtual needle in CACT images. The final, real needle position was assessed by CACT. Punctures were performed in phantoms (n = 76) and in twelve patients (eight biopsies, three drainages, one injection). Procedure times, system error, user error and total error were assessed. In phantoms, mean total error was 2.3 +/- 0.9 mm, user error was 1.4 +/- 0.8 mm and system error was 1.7 +/- 0.8 mm. In the patient study, the targeted puncture was successful in all twelve cases. The mean total error was 5.4 mm +/- 1.9 mm (maximum 8.1 mm), user error was 3.7 +/- 1.7 mm, system error was 3.2 +/- 1.4 mm and mean skin-to-target time was less than 1 min. The navigation device relying on CACT was accurate in terms of needle visualization and useful for needle placement under both experimental and clinical conditions. For more complex procedures, electromagnetic field-based tracking guidance might be of help in facilitating the puncture and reducing both the puncture risk and procedure time.

Computer systems allow the planning of complex liver operations. The segmentation of intrahepatic vessels builds the basis for the calculation of liver segments and resection proposals. For surgical use, it is essential to know the capabilities and limitations of the segmentation. The aim of this study was to determine the sensitivity and precision of the portal vein segmentation of a computer planning system for liver surgery in vivo. Segmentations were performed with the software system HepaVision on computed tomography (CT) scan data of domestic pigs. An in situ corrosion cast of the portal vein served as the gold standard. The segmentation results of the portal vein and the corrosion cast were compared with regard to sensitivity, precision, and amount of short-circuit segmentations. The methodology demonstrated high resolution ex situ. The in vivo sensitivity of the portal vein segmentation was 100% for vessels of more than 5 mm in diameter and 82% for vessels of 3–4 mm. All segment branches were detected as well as 84% of the first subsegment branches with a diameter of more than 3 mm. The precision of the system was 100% for segment branches and 89% for the first subsegment vessels. The amount of internal short-circuit segmentations was less than 3.0%. No external short-circuits were found. The system has a high precision and sensitivity under clinical conditions. The segmentation is suitable for portal vein branches of the first and second order and for vessels of ≥3 mm in diameter.

The influence of different table feeds (TF) on vascular enhancement and image quality in patients undergoing lower extremity runoff-CTA for peripheral artery occlusive disease (PAOD), acute ischemia (AI) or abdominal aortic aneurysm (AAA) with PAOD was investigated retrospectively. One hundred eighty-five patients (PAOD: n = 132; AI: n = 40; AAA: n = 13) underwent 16-detector runoff-CTA (120 kV; 140 mAs; rotation time 0.5 s, collimation 16 x 1.5 mm) using different TF (30 mm/s: n = 25; 40 mm/s: n = 91; 48 mm/s: n = 36; 56 mm/s: n = 33). Vascular enhancement of the large arteries was measured every 10 cm along the z-axis from the upper abdomen to the toe. Arterial enhancement in the distal lower leg was compared (ANOVA, Bonferroni post-test). Qualitative assessment of bolus timing was performed independently by two radiologists. The study was IRB approved. In patients with PAOD or AI, enhancement of calf arteries using a TF of 48 mm/s (278 +/- 79 HU) was significantly higher in comparison to two slower TF (30 mm/s: 201 +/- 70 HU, P0.001; 40 mm/s: 251 +/- 79 HU, P0.05; 56 mm/s: 261 +/- 57 HU, NS) and the fewest noninterpretable arterial segments below the knee were observed with a TF of 48 mm/s (reader 1: 5/121 = 4.1%; reader 2: 4/121 = 3.3%). In patients with AAA, the fewest nondiagnostic segments occurred with a TF of 30 mm/s (2/12 = 17%, both readers) and 40 mm/s (4/24 = 17%, both readers). A TF of 48 mm/s provided the best synchronization of CT data acquisition and contrast bolus propagation and thus the best image quality in patients with PAOD and AI. In patients with AAA, a slower TF of 30 mm/s provided better image quality than faster CT protocols.

The purpose of our study was to evaluate the diagnostic accuracy and scan coverage of flat-detector C-arm CT compared with that of biphasic MDCT for depicting malignant hepatic lesions in patients with hypervascular liver tumors before they undergo transarterial chemoembolization (TACE).Fifteen patients with either hepatocellular carcinoma (HCC, n = 8) or hypervascular liver metastases from uveal melanoma (n = 7) underwent arterial and portal venous C-arm CT of the liver using intraarterial contrast media administration directly before TACE. The number and location of their hepatic malignancies were compared with those on MDCT. The scan coverage was documented and the liver diameter measured on MDCT.Compared with MDCT, the sensitivity and specificity for segmental tumor involvement were 97% (76/78) and 85% (28/33), respectively, for reader 1, and 99% (77/78) and 79% (24/29), respectively, for reader 2. Complete scan coverage of the liver was obtained in five of the 15 patients with C-arm CT. In patients with incomplete scan coverage on C-arm CT, the craniocaudal liver diameter was significantly larger than in those patients with complete scan coverage (mean [95% CI], 22.7 [19.5-25.9] cm vs 20.2 [15.4-25.0] cm, p = 0.0193).Biphasic arterial and portal venous C-arm CT showed a high sensitivity for the detection of malignant liver lesions. However, the liver could not be visualized completely in two thirds of the patients. Therefore, the current scan range limitations need to be overcome to make C-arm CT a valuable adjunct to MDCT for preprocedure evaluation and postprocedure follow-up imaging.

Thermal ablation techniques like radiofrequency or laser-induced thermotherapy (LITT) are increasingly used to treat tumors of parenchymatous organs. Minimal access, parenchymal preservation, and a low complication rate render them suitable for pulmonary tumors as well. Their successful clinical application depends on the induction of sufficiently large lesions and a knowledge of the energy parameters required for complete thermal ablation. The aim of this study was to establish a dose-response relationship for a percutaneous and an intraoperative system for LITT of lung tissue. Thermal lesions were induced in healthy porcine lungs using an Nd:YAG laser (1,064 nm). LITT was performed with a percutaneous application system in group I (n = 18) and an intraoperative application system in group II (n = 90). Laser energy was applied for 600-1,200 s in a power range of 20-32 W (12,000-38,400 J). The lesions were longitudinally and transversally measured, and the volume was calculated after the intervention. Furthermore, an open application system was used to perform LITT under in vivo conditions during lung perfusion and ventilation in domestic pigs. Lesion volumes in both groups showed a plateau-like curve when the laser power increased from an initial level of 25 W. With the percutaneous puncture system (group I), the application of 28 W (16,800 J) for 10 min generated the largest lesions with a volume of 12.54 +/- 1.33 cm(3), an axial diameter of 39.33 +/- 2.52 mm, and a diametrical diameter of 24.67 +/- 1.15 mm. A longer application time was not possible due to thermal instability of the applicator. Moreover, group I started developing extensive carbonizations at a laser power of 22 W (13,200 J). The intraoperative application system (group II) achieved the largest lesion volumes of 11.03 +/- 2.54 cm(3) with diameters of 34.6 +/- 4.22 mm (axial) and 25.6 +/- 2.51 mm (diametrical) by an exposure time of 20 min and a power of 32 W (38,400 J). Here extensive carbonizations only started to occur at 28 W (33,600 J). Under in vivo conditions, all pigs tolerated the LITT procedure well without complications. Besides a typical cooling effect in the vicinity of blood vessels, the thermal lesions were about three times smaller than the ex vivo lesions. Both the percutaneous and the open LITT application system induced reproducible, clinically relevant lung lesions. The percutaneous puncture set generated large relevant lesions, although its usability is limited by its restricted capacity and high carbonization risk. It is suitable for powers up to 22 W. The intraoperative application system allows higher energy exposure to induce larger lesion volumes. This study elucidates the dose-effect relation of two clinically relevant puncture sets.

Institutional review board approval and patient informed consent were obtained. Use of a multipolar radiofrequency (RF) ablation device in patients with hepatic malignancy was prospectively evaluated with regard to feasibility, achieved ablation zone size and shape, technical effectiveness, and complications. Nineteen malignant liver tumors were treated with the multipolar resistance-controlled RF ablation system, with which up to three internally cooled bipolar coagulation electrodes can be operated simultaneously. Postinterventional imaging was performed with dynamic contrast material-enhanced magnetic resonance (MR) imaging and MR imaging-based three-dimensional planimetry. Complete tumor destruction was achieved in 18 of 19 tumors. Mean ablation zone volume was 52 mL +/- 45 (standard deviation). Thirteen patients were treated with a percutaneous approach; six, with an intraoperative approach. Maximum ablation size was 91 x 62 x 79 mm with the percutaneous and 73 x 98 x 74 mm with the intraoperative approach. Of the 18 completely evaluable ablation zones, 13 were concentric, two were moderately eccentric, two were eccentric, and one was wedge-shaped. The multipolar RF ablation device achieves large ablation zones and has high technical effectiveness in treating hepatic tumors.

PURPOSE Exact preoperative determination of the liver volume is of great importance prior to hepatobiliary surgery, especially in living donated liver transplantation (LDLT). In the current literature, a strong correlation between preoperatively calculated and intraoperatively measured liver volumes has been described. Such accuracy seems questionable, primarily due to a difference in the perfusion state of the liver in situ versus after explantation. Purpose of the study was to asses the influence of the perfusion state on liver volume and the validity of the preoperative liver volumetry prior to LDLT. METHODS In an experimental study, 20 porcine livers were examined. The livers were weighted and their volumes were determined by water displacement prior and after fluid infusion to achieve a pressure physiologically found in the liver veins. The liver volumes in the different perfusion states were calculated based on CT-data. The calculated values were compared with the volume measured by water displacement and the weight of the livers. RESULTS Assessment of calculated CT volumes and water displacements at identical perfusion states showed a tight correlation and differed on average by 4 +/- 5 %. However, livers before and after fluid infusion showed a 33 +/- 8 % (350 +/- 150 ml) difference in volume. CONCLUSION CT-volumetry acquires highly accurate data as confirmed by water displacement studies. However, the perfusion state has major impact on liver volume, which has to be accounted for in clinical use.

Zielsetzung. Bestimmung des Stellenwertes des arteriellen Stimulationstests mit venoser Blutentnahme (ASVS) zur praoperativen Lokalisation von Insulinomen. Methodik. Dreizehn Patienten mit endogenem Hyperinsulinismus wurden bei nichtkonklusiver externer Vordiagnostik praoperativ mittels transabdominellem Ultraschall (US), Spiral-CT (CT),MRT, endoskopischem Ultraschall (EUS), digitaler Subtraktionsangiographie (DSA) in Verbindung mit dem ASVS-Test untersucht. Die Resultate wurden mit intraoperativen Befunden und den histologischen Ergebnissen korreliert. Ergebnisse. Die Sensitivitaten betrugen fur US 8%,MRT 27%, CT 46%, EUS 50%,DAS 69% und ASVS 92%.Die intraoperative Palpation und Ultraschall (IOUS) erzielten eine Sensitvitat von 77%.Bei 3 Patienten war das Insulinom intraoperativ weder palpabel noch durch IOUS lokalisierbar, die Resektion erfolgte anhand der praoperativen Diagnostik. Der ASVS-Test als funktionelles Verfahren war in der Detektion den praoperativen bildgebenden Verfahren uberlegen. Schlussfolgerungen. Der ASVS-Test erwies sich als das zuverlassigste Verfahren fur die Lokalisationsdiagnostik.Vor dem Hintergrund gesundheitsokonomischer Uberlegungen sollte er bei negativer Schnittbilddiagnostik fruhzeitig eingesetzt werden.

Severe courses of Crohn’s disease (CD) during pregnancy are rare. However, if occurring, the risk of miscarriage and low birth weight is increased. At present, only limited data is available on the treatment of CD during pregnancy. In particular, there are no standard guidelines for surgical therapy. Nevertheless, surgery is often unavoidable if complications during the course of the disease arise. This study provides a critical overview of conventional and interventional treatment options for CD complications during pregnancy and analyses the surgical experience gained thus far. For illustrative purposes, clinical cases of three young women with a severe clinical course during pregnancy are presented. After treatment-refractory for conservative and interventional measures, surgery remained as the only treatment option. In all cases, a split stoma was created after resection to avoid anastomotic leaks that would endanger the lives of mother and child. The postoperative course of all three patients was uneventful, and pregnancy remained intact until delivery. No further CD specific medication was required before birth. The management of CD patients during pregnancy requires close interdisciplinary co-operation between gastroenterologists, obstetricians, anaesthetists and visceral surgeons. For the protection of mother and child treatment should thus be delivered in a specialised centre. This article demonstrates the advantages of surgical therapy by focusing on alleviating CD complaints and preventing postoperative complications.

Purpose We report on a multicenter phase II trial of 90yttrium-ibritumomab-tiuxetan (90YIT) as first-line stand-alone therapy for patients with follicular lymphoma (FL). Patients and Methods Fifty-nine patients with CD20+ FL grade 1 to 3a in stages II, III, or IV, age 50 years old or older requiring therapy were enrolled. They received 90YIT according to standard procedure. If complete response (CR) or unconfirmed complete response (CRu) without evidence for minimal residual disease (MRD) 6 months after application of 90YIT was achieved, patients were observed without further intervention. The same applied to patients with partial response (PR) or with stable disease (SD). Patients with CR but with persisting MRD were to receive a consolidation treatment with rituximab. Primary end point was the clinical and molecular response rate. Secondary end points were time to progression, safety, and tolerability. Results Six months after treatment with 90YIT, 56% of the patients showed a CR or CRu and 31% achieved a PR. After a median follow-up of 30.6 months, the progression-free survival (PFS) was 26 months. There was a trend for shorter PFS in patients with increased lactate dehydrogenase (LDH). Of the 26 patients who had CR 12 months after 90YIT, only three had relapsed. Median time to next treatment has not been reached. The most common toxicities were transient thrombocytopenia and leukocytopenia. Nonhematologic toxicities never exceeded grade 2 according to Common Terminology Criteria for Adverse Events (CTCAE v2.0). Conclusion 90YIT is well tolerated and achieves high response rates. Patients with increased LDH tend to relapse earlier, and individuals in remission 1 year after 90YIT appear to have long- lasting responses.

Periphere MR-Angiographien mit hoher ortlicher Aufl osung und arteriellem Kontrast wurden mit einer vor kurzem vorgestellten Computer-Methode erzeugt. Steady-State und First-Pass MRAngiographien der Unterschenkel von 10 Patienten wurden zu hoch aufgel osten arteriellen MR-Angiographien kombiniert. Die Bildqualitat wurde sehr gut bewertet. Die Ergebnisse einer Befundung von Stenosen waren sehr nah an denen der Steady-State MR Angiographien, die den Standard darstellten.

Peripheral MR angiography requires high resolution and arterial contrast. Neither can be obtained simultaneously due to the short arterial phase of the contrast agent. To improve temporal resolution, keyhole imaging was developed, which combines high resolution and arterial k-spaces at the time of image acquisition. Here, a related approach is introduced for image post-processing in the Fourier domain. It is demonstrated that simple substitution of the central k-space with low-resolution data leads to severe distortion. Hence, a dedicated calculation scheme is necessary for composite k-space post-processing. A solution is presented for high-resolution arterial peripheral MR angiography that uses subtraction of venous intensities from the central high-resolution k-space. The calculations in the Fourier domain do not require interpolations between the different resolutions. High-resolution steady-state MR angiography, which exhibits contrast-enhanced arteries and veins at an isotropic resolution of 0.65 mm, and standard resolution arterial first-pass MR angiography were combined to obtain images with the resolution of the steady-state images and arterial contrast. Numerical simulations on software phantoms are presented. The operation of the method is demonstrated in five patients.

Einleitung: Die onkologische Sicherheit der Radiofrequenzablation (RFA) ist insbesondere durch den Kühleffekt großer Lebergefäße eingeschränkt. Ziel der vorliegenden Studie war es, ein interdisziplinär entwickeltes Planungssystem für die RFA von Lebertumoren in Hinblick[for full text, please go to the a.m. URL], 127. Kongress der Deutschen Gesellschaft für Chirurgie

A 26-year-old man was admitted to hospital with a 6-month history of diarrhea and abdominal pain. Before admission, upper and lower gastrointestinal endoscopy had shown a mild erosive duodenitis and the patient was started on a proton pump inhibitor. Physical examination and laboratory tests on admission were not constructive. In addition, repeated gastrointestinal endoscopy, cross-sectional imaging and neuroendocrine markers did not point to a specific etiology. Therefore, as a provocation test, the proton pump inhibitor therapy was discontinued. Discontinuation resulted in a progression of the patient's symptoms and an endoscopic detection of duodenal ulcers. Except for the normal serum gastrin levels, this constellation was suggestive of a gastrinoma, so that further investigations were initiated. Subsequently, the diagnosis could be confirmed and the gastrinoma located. After successful pancreaticoduodenectomy, the patient was symptom-free.As part of a systematic investigation on chronic diarrhea, the work-up for neuroendocrine causes can play an important role. In this context, it should be kept in mind that some gastrinoma patients present without an elevation of serum gastrin levels. Regardless of a negative gastrin test, a typical symptom constellation should therefore prompt further investigations.

This study was designed to evaluate whether the computed tomography (CT) reflects the extent of the inflammation in sigmoid diverticulitis (SD) in order to draw conclusions for selecting the appropriate treatment. Two hundred four patients who underwent resection for SD from January 2003 to December 2008 were included. The preoperative CT stage was compared with intraoperative and histological findings. Patients were classified into phlegmonous (Hansen–Stock IIa), abscess-forming (HS IIb), and free perforated (HS IIc) forms of SD. Patients with a recurrent type of diverticulitis were excluded. In the phlegmonous type (HS IIa; n = 75), we found a correlation with the preoperative stage in 52% (intraoperative) and 56% (histological), an understaging in 12% (intraoperative) and 11% (histological), and an overstaging in 36% (intraoperative) and 33% (histological). In the abscess-forming type (HS IIb, Hinchey I/II; n = 87), we found conformity in 92% (intraoperative) and 90% (histological), understaging in 3% (intraoperative) and 0% (histological), and overstaging in 5% (intraoperative) and 10% (histological). In the presence of a free perforation (HS IIc, Hinchey III/IV; n = 42), we saw conformity in 100% (intraoperative and histological). The positive predictive value for correctly diagnosing of phlegmonous type (HS IIa), abscess-forming type (HS IIb), and free perforation (HS IIc) by CT was intraoperatively (histologically) 52% (56), 92% (90), and 100% (100), respectively. The CT is one of the most accurate methods for staging in SD. However, in the phlegmonous type (HS IIa), it leads to an overestimation of the findings in every third patient. It must be clarified whether this pronounced low inflammation should really be regarded as a complicated form of SD. In contrast, the abscess-forming (HS IIb) and free perforated (HS IIc) type of complicated SD is very well reflected by CT.

The objective of our study was to prospectively evaluate quantitatively and qualitatively the enhancement patterns of cirrhotic liver tissue and hepatocellular carcinoma (HCC) after administration of the hepatocyte-specific contrast agent gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) on dynamic MRI and to determine the time point of maximum liver-to-lesion contrast.Twenty-five patients with HCC in liver cirrhosis underwent 1.5-T MRI. T2-weighted turbo spin-echo and T1-weighted 3D gradient-echo sequences before and between 15 seconds and 20 minutes after the injection of 10 mL of Gd-EOB-DTPA were performed. Signal-to-noise ratios (SNRs) of liver parenchyma and liver-to-lesion contrast-to-noise ratios (CNRs) were calculated and plotted over time. Enhancement patterns of HCC were characterized qualitatively by two radiologists.The SNR of liver parenchyma increased significantly at 15 seconds and 60 seconds after contrast injection and remained stable thereafter. HCC showed positive CNR during the arterial phase and increasingly negative CNR during the further time course (p0.05). The maximum absolute CNR was found at 20 minutes after contrast injection. There was no correlation between the degree of enhancement at any time point and tumor grade. On qualitative evaluation, 16 HCCs showed arterial enhancement with early washout, and five showed arterial enhancement with late washout. In the remaining four HCCs, enhancement persisted until 20 minutes. Lesion conspicuity at 20 minutes after contrast injection was at least equal to or higher than it was on the remaining sequences in 19 of the 25 patients.After Gd-EOB-DTPA injection, most HCCs showed typical arterial enhancement with early washout. Liver-to-lesion contrast was best at 20 minutes.

Bipolar radiofrequency ablation (RFA) can avoid complications such as thermal tissue damage, a possible consequence of monopolar RFA. However, basic studies about the dosage/effect relationship of bipolar systems are missing. This is systematic research on ex vivo beef livers to find which capacity parameters produce high energy in the tissue and achieve large lesion volumes.The active lengths 20, 30 and 40 mm of a bipolar, internally cooled applicator were studied. The tissue was fresh ex vivo beef liver. Five measurements each for each active applicator with a power between 10 and 50 W were conducted.The best power for the 20 mm applicator was 15 W, since the highest achieved volume was 5,599+/-1,760 mm(3) and the highest amount of energy introduced to the tissue was 15+/-3 kJ. The best power for the 30 mm applicator was 20 W (volume 14,538+/-1,220 mm(3), energy 24+/-1 kJ). For the 40 mm applicator, the best power was 20 W, (volume 20,562+/-896 mm(3), energy 24+/-0 kJ).The results of this study help clinicians determine which active length is required for the applicator and which presetting should be selected to achieve a defined coagulation volume size.

Ziele: Vasovist (Bayer Schering) ist ein Blutpool-Kontrastmittel fur die MRA. Zusatzlich zur konventionellen First Pass (FP) MRA in der arteriellen Phase erfolgt mit diesem KM die Akquisition hoch aufgeloster Steady State (SS) Bilder wahrend der Blutpoolphase. Ziel unserer prospektiven Studie war der intraindividuelle Vergleich der FP-MRA kombiniert mit SS-Bildgebung im Vergleich zur alleinigen FP-MRA mit Vasovist im Hinblick auf die diagnostische Beurteilbarkeit der arteriellen Segmente unter- und oberhalb des Knies. Methode: Bei 82 Patienten mit pAVK erfolgte zunachst eine „step by step“ FP-MRA (9ml Vasovist @ 1ml/s sowie 30ml Kochsalzlosung @ 0,5ml/s) mit einem 1,5T Scanner (Avanto, Siemens) und 3D T1w-Sequenzen mit einer Voxel-Grose von 0,9×0,9×1,5mm. Anschliesend erfolgte die hoch auflosende SS-Bildgebung bei 0,65×0,65×0,65mm Voxelgrose. Ein verblindeter externer Beobachter beurteilte zunachst nur die FP-MRA und anschliesend die kombinierte FP+SS-MRA. Ergebnis: Es wurden 820 Unterschenkelsegmentarterien beurteilt. In der First Pass-MRA wurden 97,6% dieser Segmente als diagnostisch eingeschatzt, diese Rate konnte durch FP+SS 99,2% gesteigert werden (p

Objective: During RF ablation of liver tumours it is a risk of incomplete tumor areas along the liver vessels. Up to now, there is no systematically analysis of the influence of vessel diameter and flow velocity on the intensity of heat dissipation during therapy available. The objective of this study was to quantify this cooling effect in an ex vivo model. Methods: In our experimental setup with fresh porcine liver we used a bipolar applicator with 30W output power and 15 kJ energy. For the simulation of different vessel diameters, glass tubes with different diameters (di=1.0–8.0 mm) were inserted. The distance between RF applicator and glass tubes was 5 mm. For the simulation of different flow velocities, for the glass tube with diameter di=3,4 mm we varied the flow velocity from 0–917.35 mms−1. After the ablation, the dimensions of the resulting lesion were digitally measured. Results: 144 lesions were induced in 48 porcine livers with 6 repetitions for each parameter setting. In the results for the different vessel diameters, there is no significant difference between the lesion sizes. But the flow velocities are clearly influencing the lesion size. Already with a flow of 1.84mms−1 we could measure a significant area reduction of 16.2% compared to zero flow, which stepped up to 33.6% area reduction for 917.35 mms−1 flow velocity. Conclusion: In a standardised ex vivo model could be shown, that the main influence is not the vessel diameter but rather the blood flow. Even for low flow rates, the heat reduction is enough to significantly reduce the lesion size. These results could be helpful for clinical therapy planning when the tumor is close to liver vessels with significant blood flow.

OBJECTIVE:: To evaluate the diagnostic efficacy (accuracy, sensitivity, specificity) of 1.0 M gadobutrol versus 0.5 M gadopentetate for the classification of lesions as either benign or malignant in patients with known or suspected liver lesions. METHODS AND MATERIALS:: A multicenter, phase-III, randomized, interindividually controlled comparison study with blinded reader evaluation was performed to investigate the diagnostic efficacy of a bolus injection of 1.0 M gadobutrol compared with 0.5 M gadopentetate at a dose of 0.1 mmol Gd/kg BW.The imaging protocol included a dynamic 3D-evaluation, static conventional, and fat saturated T1-weighted sequences. MR datasets were evaluated by 3 independent radiologists. The standard of reference was defined by an independent truth panel (radiologist or hepatologist).The safety evaluation included adverse events, vital signs, and physical examination. RESULTS:: A total of 497 of 572 patients were eligible for the final efficacy analysis. Noninferiority of gadobutrol-enhanced magnetic resonance imaging (MRI) for the classification of liver lesions was demonstrated on the basis of diagnostic accuracy determined by the on-site investigators (-0.098, 0.021) as well as for the average reader of the blinded evaluation (-0.096, 0.014) (95% confidence interval), compared with the predefined standard of reference. Very similar increases in sensitivity (ranging from approximately 10% to approximately 55%) and specificity (ranging from approximately 1%- approximately 18%) compared with precontrast MRI were also observed for the 2 contrast agent groups, with maximum differences of 4%.Very similar, low rates of adverse events were recorded for each of the 2 groups. No clinically relevant changes in vital signs or the results of the physical examination were observed in any patient. CONCLUSION:: This study documents evidence for the noninferiority of a single i.v. bolus injection of 1.0 M gadobutrol (0.1 mmol/kg body weight) to 0.5 M gadopentetate (0.1 mmol/kg body weight) in the diagnostic assessment of liver lesions with contrast-enhanced MRI. The known excellent safety profile of gadobutrol was confirmed in this clinical trial and is similar to that of gadopentetate.

Background: Magnetic resonance (MR)-guided interventions have evolved from a pure research application to a preclinical method over the last decade. Among the device-tracking techniques, susceptibility artifact-based tracking relies on the contrast between the surrounding blood and the device, and radiofrequency coil-based tracking relies on the local gradient field amplification in a resonating circuit attached to the interventional device. Purpose: To evaluate the feasibility and precision of susceptibility artifact-based and microcoil-based MR guidance methods for renal artery stent placement in a swine model. Material and Methods: MR imaging-guided renal artery stent placements were performed in six fully anesthetized pigs using a 1.5T short-bore MR scanner. Susceptibility artifact-based tracking with manual scan-plane adjustments and microcoil tracking with automatic scan-plane adjustments were used for renal artery stent placements in three pigs in each group. With both methods, near real-time steady-state free-precession (SSFP) imaging was used. Differences between the two tracking approaches on stenting time, total procedure time, and stent position were measured. Results: The microcoil-based approach yielded a shorter mean procedure time (17 vs. 23 min). There was no relevant difference for the mean stenting time (12 vs. 13 min). The mean stent deviation from the aortic wall with the susceptibility approach was larger than with the microcoil approach (10 vs. 4.0 mm). Conclusion: For MRI-guided renal artery stent placement, the microcoil-based technique had a shorter procedure time and a higher stent placement precision than the susceptibility artifact-based approach.

The purpose of the study was to prospectively evaluate intrahepatic vessel depiction on C-arm CT (CACT) and the influence of the additional combined tissue and three-dimensional vessel visualisation on the positioning of the TACE catheter in comparison to DSA alone. Thirty consecutive patients scheduled for their first transarterial chemoembolisation underwent biphasic CACT and DSA of the liver. After assessing the DSA images for procedure planning, the CACT images were reviewed. The number and origin of the tumour-feeding arteries and the ideal position of the catheter for TACE on both DSA and CACT were assessed and correlated. The number of vessels identified as tumour feeders in each patient was significantly higher using additional CACT than on DSA alone (CACT: 4.0 +/- 1.7; DSA: 3.3 +/- 1.4; P = 0.003, t-test). After considering CACT, in 50% of the patients the catheter position was changed for TACE. Segmental portal vein thrombosis was seen in three patients on CACT, but in only one on DSA. As CACT depicts soft tissue and small vessels with high spatial resolution, tumour vessel allocation is facilitated, and ideal catheter position for TACE can be more accurately identified. The high impact of CACT on the TACE procedure suggests the benefits of its routine use for all patients undergoing their first TACE.

We prospectively compared hepatic transit time (HTT) measurements in subjects with liver metastases from colorectal cancer (group a) and healthy volunteers (group b) using contrast-enhanced ultrasound with BR1. The purpose of this study was to verify our hypothesis that the hemodynamic changes of the liver, which occur during metastasis seeding, would shorten the HTT, and we expect that such changes could be used for the detection of occult liver metastases from colorectal cancer in the future. The study had institutional review board approval and all subjects gave informed written consent. Group a and group b consisted of 22 subjects each. Baseline and post contrast images were acquired starting 10 s before and ending 40 s after administration of BR1, using nonlinear imaging at a frame rate of 5/s. The baseline images were used to determine the signal intensity without contrast enhancement as the reference signal. Arrival times (AT) of the contrast agent for the hepatic artery, the portal vein and one hepatic vein were determined using (i) quantitative analysis and (ii) subjective analysis by two blinded readers. HTT was calculated based on arrival time measurements. Quantitative and subjective analysis showed significantly shorter arterial to venous and portal to venous HTT in group a compared with group b (p0.001). Arterial to venous HTT (quantitative analysis) wasor = 9 s in 19 of 22 subjects of group a and9 s in 18 of 22 subjects of group b (sensitivity 86%, specificity 82%, positive predictive value 83%, negative predictive value 86%, area under the curve [AUC] 0.87). Portal to venous HTT (quantitative analysis) was7 s in 21 of 22 subjects of group a and7s in 15 of 22 subjects of group b (sensitivity 95%, specificity 68%, PPV 75%, NPV 94%, AUC 0.85). There was an inverse relation with number of liver segments involved for arterial to venous and portal to venous HTT in group a (p0.05), but no correlation between HTT and overall volume of metastases (group a) or subject age (group b). From the results of our study, we conclude that HTT measurements using contrast-enhanced ultrasound with BR1 can detect hemodynamic changes caused by metastatic liver disease from colorectal cancer. However, comparison with the literature suggests that the use of other contrast agents might provide better results. Comparison of different contrast agents for the purpose of transit time analysis would therefore be useful before embarking on a prospective trial looking at the detection of occult liver metastases in patients with colorectal cancer. (E-mail: jhohmann@uhbs.ch).