[Fever and right upper abdominal pain in a 26-year-old returning from travel abroad]. / Fieber und rechtsseitige Oberbauchschmerzen bei einem 26-jährigen Reiserückkehrer.

Persistent fever and unspecific general symptoms need a complete and detailed medical history and search for infection. We report on a case of amebiasis with liver abscesses of a 26-year-old man. He had stayed several weeks in India and South America. After being free of complaints for 4 months, unspecific general symptoms and fever appeared. Due to proven liver abscesses, a combination treatment was given. Within 12 days, he was free of symptoms and could be discharged.

[Venous interventions. Part 2: Thromboses of the upper torso and mesenteric veins]. / Venöse Interventionen. Teil 2: Thrombosen der oberen Körperhälfte und der mesenterialen Venen.

This article focuses on the percutaneous treatment options of venous thromboses and occlusions. Interventional therapy modalities for mediastinal, brachial, axillar, cerebral, and mesenteric thromboses are reviewed. Stenoses of the superior vena cava are most often caused by mediastinal malignomas. Balloon angioplasty together with stent implantation is an effective method for revascularisation in cases of upper venous congestion. Benign central venous stenoses are common in dialysis patients for whom interventional therapy using balloon angioplasty has proven excellent results. In the treatment of insufficient dialysis access, percutaneous techniques represent the first-choice option. Regarding cerebral and mesenteric thrombosis, interventional therapy is restricted to selected individual cases.

[Embolotherapy: principles and indications]. / Grundlagen der Embolisation und anderer verschliessender Verfahren.

Vascular embolizations are complex and sophisticated procedures and can be a powerful alternative or useful adjunct to surgery in many clinical situations. Hemorrhage, vascular malformations, and tumors are the main indications for embolization procedures. Establishing the correct indication for intervention as well as the proper embolic agent and the most suitable catheterization technique requires advanced knowledge in interventional radiology, and an interdisciplinary approach is a prerequisite. A broad spectrum of microcatheters and embolization materials is available for these therapies. The desired level of occlusion and the individual vascular territory determine the choice of mechanical devices, particles, or liquid substances. Sclerosing agents and thrombin are used in special situations such as varicoceles and pseudoaneurysms.

[Emergency radiology of bowel obstruction]. / Radiologische Akutdiagnostik bei Darmobstruktion.

Clinical radiology is a key to the management of bowel obstruction. Plain abdominal radiographs combined with history, clinical exam, and laboratory findings are essential for further individualized strategies. If the cause of obstruction is obvious after plain films and there is a need for emergent surgery, no further imaging is required. In all other cases, multislice CT with at least intravenous and rectal contrast is the method of choice due to its broad diagnostic spectrum. If CT is not available, contrast enema is recommended in suspected large bowel obstruction. Oral administration of water-soluble contrast agents has no significant value in the workup of bowel obstruction.

In vitro evaluation of intravascular stent artifacts in three-dimensional MR angiography.

RATIONALE AND OBJECTIVES: To evaluate the intraluminal signal characteristics of various stents and stent-grafts in contrast-enhanced three-dimensional MR angiography (3D MRA) in vitro. METHODS: Fourteen stents made of different materials (steel, nitinol, tantalum, cobalt-based alloy, polyethylene) and six stent-grafts were implanted in plastic tubes simulating the common iliac artery. The tubes were filled with gadopentetate dimeglumine in water at a concentration of 25 mmol/L and positioned in a plastic container filled with water. For imaging, the container was placed in the center of the magnet, parallel, orthogonal, and diagonal to the z axis. A 3D gradient-echo sequence (T1-FFE) was acquired with the following parameters: repetition time 5.3 ms, echo time 1.6 ms, flip angle 50 degrees, slice thickness 1.5 mm, and acquisition matrix 256 with zero filling to 512. To evaluate the influence of the frequency-encoding gradient on the appearance of the artifacts, stents were examined with their axes oriented in all three directions both with the frequency-encoding gradient in the feet-head and right-left directions. The size and pattern of stent-related artifacts were evaluated semiquantitatively for each measurement. RESULTS: Five different components of artifacts could be distinguished: homogeneous signal reduction inside the stent, narrowing of the stent lumen, structures of various shapes inside the stents, signal reduction or signal increase at the ends of the stents, and shift of the intraluminal signal orthogonal to the longitudinal axis of the vessel. The size of the artifacts depended heavily on the material of the stent. The polyethylene stent showed no artifacts, the tantalum stent only minor artifacts. Nitinol stents were characterized by artifacts at both ends and signal reduction intraluminally. Stents made of steel demonstrated the strongest artifacts, characterized by almost complete signal loss intraluminally. The characteristics of the artifacts of all stents depended on the direction of the stent relative to the frequency-encoding gradient. CONCLUSIONS: Three-dimensional MRA follow-up after stent placement may be applicable for stent patency evaluation in all instances. However, grading of stenoses seems to be unrealistic in steel stents and in most nitinol stents.

Angiographic detection of gastrointestinal bleeding. An experimental comparison of conventional screen-film angiography and digital subtraction angiography.

RATIONALE AND OBJECTIVES: The authors experimentally assess and compare the detection limit of gastrointestinal bleeding in digital subtraction angiography (DSA) and conventional screen-film angiography. MATERIALS AND METHODS: Arterial blood flow was simulated using a tube model in which bleeding was imitated by exudation of liquid containing contrast material. Gut peristalsis was imitated using silicone tubes filled with air and liquid. Images were acquired by DSA and conventional screen-film angiography. The iodine concentration was increased in increments from 1 mg I/mL, with and without simulated peristalsis, and with both free and circumscribed extravasation of contrast material. RESULTS: The detection limit for free extravasation in DSA was 1 mg I/mL without peristalsis and 60 mg I/mL with peristalsis. The corresponding figures for circumscribed extravasation were 1 mg I/mL and 34 mg I/mL. The detection limit for free extravasation in screen-film angiography was 172 mg I/mL both with and without simulated peristalsis. Circumscribed extravasation was detected at 9 mg I/mL without peristalsis and 7 mg I/mL with peristalsis. CONCLUSION: Digital subtraction angiography is the more sensitive angiographic technique for detection of gastrointestinal bleeding and is superior to conventional screen-film angiography, provided that it is performed with adequate parasym-pathicolysis and suspended respiration. Only when these requirements cannot be achieved is screen-film angiography advantageous.

Spiral CT angiography of the abdominal aorta. Comparison of iodixanol and ioversol.

RATIONALE AND OBJECTIVES: Enhancement characteristics of a nonionic, dimeric, isotonic contrast medium (iodixanol [Visipaque]) were compared with a nonionic, monomeric contrast medium (ioversol [Optiray]) of the same iodine concentration in spiral computed tomography angiography (CTA) of the abdominal aorta. METHODS: Spiral CTA was performed in 78 patients referred for suspected renal artery stenosis (n = 35) and abdominal aortic aneurysm (n = 43). A test bolus was used to time the scan delay, and all patients were injected with 150 ml contrast medium (320 mgI/ml) of either iodixanol (n = 40) or ioversol (n = 38). Contrast enhancement was measured in the aorta, renal arteries, and renal parenchyma. RESULTS: All mean aortic enhancement was slightly higher with iodixanol than ioversol, measured at three different levels (celiac trunk 315 Hounsfield units [HU] versus 300 HU, renal arteries 325 HU versus 312 HU, aortic bifurcation 276 HU versus 266 HU). However, none of them were statistically significant (e.g., P = 0.26 at the celiac trunk level). Similar results were observed in renal artery and parenchyma enhancements. CONCLUSIONS: Iodixanol and ioversol had similar enhancement characteristics in the early arterial phase. Both substances were well tolerated and seem to be well suited for spiral CTA.

Vasoreactivity of arterial grafts in the patient with diabetes mellitus: investigations on internal thoracic artery and radial artery conduits.

OBJECTIVE: Arterial revascularization with either internal thoracic artery (ITA) or radial artery (RA) appears to be particularly attractive in diabetic patients. Previous investigations have shown that endothelial dysfunction and artherosclerosis are seen more often in these patients. The aim of this study was to compare the vasoreactive properties of ITA and RA grafts in diabetic and non-diabetic patients. METHODS: Arterial rings were harvested from 57 patients who underwent complete arterial revascularization. The patients were divided into a non-diabetic group (I: n = 30) and patients with diabetes mellitus (II: n = 27). Arterial rings of the ITA (I: n = 30; II: n = 27) and RA (I: n = 28; II: n = 19) were mounted on a strain gauge in oxygenated, normothermic Krebs's--Henseleit solution at optimal resting tension. With KCL (80 mM) serving as the control, assessment of force of contraction (norepinephrine), endothelium-dependent relaxation (acetylcholine) and smooth muscle-dependent relaxation (glyceroltrinitrate) were obtained. RESULTS: After KCL, the RA showed a trend to lower maximum contraction forces in diabetics (I: 76 +/- 25 mN; II: 69 +/- 29 mN), which was pronounced in patients with diabetes of more than 10 years duration (55 +/- 23 mN; P = 0.1). Maximum contraction force of the ITA was similar in both groups (I: 41 +/- 20 mN; II: 34 +/- 19 mN) and not influenced by the duration of diabetes. The two groups showed no significant differences of the relative vasoconstriction after norepinephrine in RA (I: 53 +/- 18%; II: 61 +/- 19%) and ITA rings (I: 70 +/- 23%; II: 69 +/- 25%). Also, endothelium-dependent relaxation with acetylcholine in RA (I: 53 +/- 14%; II: 57 +/- 16%) and ITA rings (I: 42 +/- 17%; II: 44 +/- 20%), and smooth muscle relaxation with glyceroltrinitrate of RA (I: 72 +/- 8%; II: 73 +/- 12%) and ITA rings (I: 64 +/- 12%; II: 58 +/- 20%) was comparable in both groups. No influence of duration of the diabetic disease was noted. CONCLUSIONS: Although RA rings of patients with a long duration of diabetes have decreased maximum contraction forces, their relative vasoconstriction after norepinephrine, endothelium-dependent relaxation and smooth muscle relaxation was similar to non-diabetic patients. We thus conclude that the RA is an adequate arterial conduit in the patient with diabetes mellitus.

Imaging of renal lesions: evaluation of fast MRI and helical CT.

The purpose of this study is to compare triphasic helical CT and fast MRI with respect to detection, characterization and staging of suspected renal masses. To achieve this triphasic helical CT (plain, corticonephrographic and tubulonephrographic phase) and MRI with fast T(1) weighted and T(2) weighted sequences were performed in 29 patients with a suspected renal lesion. Image quality, lesion characterization and lesion extent were assessed for both methods in all patients. The acquisition phase for CT and the image sequence for MRI offering the best image quality and best diagnostic information regarding renal parenchyma, renal vessels, detection of enlarged lymph nodes, and other abdominal organs were determined. Histologically confirmed renal cell carcinomas (n=18) were staged based on the Robson classification. Quantitative data were obtained from operator-defined regions of interest (ROIs) in all acquisition phases (CT) and all image sequences (MRI). For most criteria the rating of image quality for helical CT was generally higher as compared with fast MRI. CT and MRI detected all 24 histologically proven masses, while no false positive solid tumour was diagnosed with both imaging modalities. All three acquisition phases in CT and all applied image sequences in MRI were regarded as necessary in order to gain important diagnostic information. Altogether, 12 of 18 renal cell carcinomas (67%) were correctly staged by CT and MRI. Helical CT and fast MRI allow the correct detection and characterization of suspicious renal lesions. Both imaging modalities can be recommended for clinical routine application. Although the correct histological staging of renal cancer remains difficult for both imaging methods, both are excellent in providing the critical staging information needed before surgery. Helical CT offers a significantly shorter acquisition time to cover the entire abdomen.

MR-guided core biopsies using a closed 1.0 T imager. First clinical results.

OBJECTIVE: High soft-tissue contrast and multiplanar imaging capabilities of MRI may be advantageous in biopsy guidance compared to CT. We report our first results with MR-guided core biopsies using a closed 1.0 T MR imager. METHODS AND PATIENTS: In ten patients, seven liver lesions and one lesion each in the muscle of the back, the gluteal muscle and in the breast were biopsied under MR guidance using MR-compatible needles (Tru-Cut type, 18G and 14G). For control scans T1-weighted turbo-spin-echo (TSE), gradient-echo and T2-weighted TSE sequences were used. RESULTS: In all patients, the suspicious lesions and the biopsy needle were exactly delineated in MR control scans. In nine out of ten patients, the suspicious lesion was clarified histologically. Controls of needle position in a second plane were performed twice. Pushing the inner stylet alone resulted in a distortion of the needle in several cases in its flat area. The small diameter of the MR gantry was inconvenient for a few patients. One complication (intrahepatic bleeding) was observed, which healed up without consequences. CONCLUSION: Using a closed 1.0 T MR imager MR-guided core biopsies can be conducted efficiently. Core biopsies should be taken by pulling and pushing the outer cannula. Advantageous compared to CT are the multiplanar imaging capabilities, while the smaller gantry is disadvantageous.

Calculation of flow velocities from the geometrical shape of contrast agent-induced time-density curves using DSA.

A method for the calculation of flow velocities in vessels is introduced. The method is validated by measurements with an artificial model. Measurements with the carrier fluids sodium chloride solution and human blood using various scattering objects, show good correlation (r greater than +0.9) of the calculated and volumetrically measured velocities. With a menu-oriented computer program, measurement of flow velocities on DSA series can be made following the routine clinical examination.

[Color-coded duplex sonography before and after PTA of the arteries of the lower extremities]. / Farbkodierte Duplexsonographie vor und nach PTA der Arterien der unteren Extremität.

The value of color-coded duplex sonography in the pelvic and lower limb arteries was studied prospectively in 52 patients and the findings were compared with intra-arterial DSA. There was high diagnostic accuracy (sensitivity 91.7%, specificity 98.9%) for the demonstration of vascular abnormalities. In 84.3% of cases a correct diagnosis could be obtained based entirely, or largely, on the color-coded signal. Both before and after PTA color-coded duplex sonography is a non-invasive method that is superior to conventional duplex sonography.

[Dilatation and balloon-expandable stents for the treatment of central venous stenosis in dialysis patients]. / Dilatation und ballonexpandierbare Stents zur Therapie zentralvenöser Stenosen bei Dialysepatienten.

On 10 dialysis patients we performed 12 balloon dilatations, 2 catheter lyses, 6 stent implants (Palmaz stent) and one atherectomy of central venous stenoses or occlusions (v. subclavia, v. brachiocephalica) at the shunt arm of the patient. The primary success rate was, in balloon PTA and lysis, 12/14 interventions, and in stent placement and atherectomy 7/7. The angiographical and clinical primary result after stent implantation was significantly better than after conventional dilatation. After 66% of the balloon dilatations recidivation occurred within the first year; this can be treated by means of repeated PTA. Whether long-term exclusion of recurrence can be achieved by stent implantation, must be established by means of follow-up studies that are at present in progress.

[In vitro measurement of intravascular blood flow with color Doppler sonography]. / In-vitro-messung des intravasalen Blutflusses mit der Farb-Doppler-Sonographie.

The accuracy of colour Doppler sonography for measuring various aspects of intravascular flow (volume and velocity), under varying conditions, was studied experimentally. The effect of variable Doppler angles, different flow paths, frequency and vessel diameter on flow profiles was examined. At all levels of measurement (range 14 ml/min to 566 ml/min) there was a very close correlation between the actual and measured values (r greater than 0.99) and high accuracy. In the detection of very slow flow rates, the use of a specific high pass filter technique was able to quantify blood flow velocities of just under 1 cm./second. Multigated colour Doppler sonography is better for measuring flow volumes than a single channel duplex system.

[Vascular diagnosis with color-coded duplex sonography. A cost-benefit analysis]. / Gefässdiagnostik mit der farbkodierten Duplexsonographie. Eine Kosten-Nutzen-Analyse.

In a retrospective study over two years, the costs of 2909 CCDS examinations were compared with 1893 digital subtraction angiograms. The cost of each CCDS examination was calculated as 147 DM and each DSA examination with intra-arterial contrast medium, or for shunt angiography was 709 DM. By using CCDS, it was possible to reduce the cost of angiographic examinations by 177,000 DM per year.

[The frequency of false aneurysms of the femoral artery following heart catheterization and PTA (percutaneous transluminal angioplasty)]. / Häufigkeit des Aneurysma spurium der Arteria femoralis nach Herzkatheteruntersuchung und PTA.

In a prospective study, the arterial puncture site was studied sonographically in 1120 patients who had undergone cardiac catheterisation or angioplasty (renal or extremities). Contrary to the figures in the literature, there was an incidence of 3.84% of false aneurysms (catheters 5.26%, angioplasty 2.36%). Conventional sonography and colour-coded duplex sonography were of equal value for demonstrating false aneurysms, but colour-coded duplex sonography was superior for demonstrating their relationships and haemodynamic effects.

[The value of digital subtraction sialography compared to conventional sialography, salivary gland sonography and surgical findings]. / Wertigkeit der digitalen Subtraktionssialographie im Vergleich mit konventioneller Sialographie, Speicheldrüsensonographie und Operationsbefund.

In a prospective study DSA sialography, conventional sialography (100mm technique) and sonography of the salivary glands were performed in 124 patients. The results of imaging could be correlated with those of operation and/or histology in 70 patients. Performing sialography in only one projection DSA sialography is superior to the conventional technique. The results of DSA are equivalent to those of conventional sialography in more than one projection. DSA sialography is the method of choice demonstrating salivary calculi, whereas sonography is superior to DSA sialography in the detection of tumors. In the diagnosis of chronic inflammation of the salivary glands DSA is slightly superior to the other imaging modalities.

[Imaging properties of digital image-intensifier radiography compared to the conventional x-ray technic for chest pictures]. / Abbildungseigenschaften der Digitalen BV-Radiographie im Vergleich zur konventionellen Röntgentechnik für Thoraxaufnahmen.

Projection properties of a digital fluorographic system for chest examinations are examined using varying test phantoms. A maximal geometric distortion of +14% between the centre and the periphery of the image intensifier and a maximal spatial resolution of 2.6 LP/mm is found. Contrast detail diagrams are used to show the combination of spatial and contrast resolution of the system. Compared with diagrams for conventional radiographic systems there is a significant loss of resolution.

[Digital image intensifier radiography and film-screen combinations in pulmonary nodules]. / Digitale BV-Radiographie und Film-Folien-Kombination bei Lungenrundherden.

30 patients with known or suspected pulmonary nodules were examined using a digital image intensifier radiography system, a conventional radiography system and a tomography of the whole lung. 73.8% of the pulmonary nodules detected with tomography were also detected with the digital system, 69.1% with the conventional system. There was no significant difference between the two systems comparing false positive and false negative diagnoses. Regarding the dose reduction to nearly 25% of that of a conventional examination the digital technique should be preferred to the conventional technique, if pulmonary nodules are suspected.

[The determination of myocardial mass by cardiac magnetic resonance tomography. The effect of section alignment and section distance]. / Myokardmassenbestimmung mit der Kardio-Magnetresonanztomographie. Einfluss von Schichtorientierung und Schichtabstand.

The effect of section alignment and distance in volumetric determination of myocardial mass by means of cardiac magnetic resonance imaging (MRI) was studied in 19 isolated pig hearts. Double angulated views taken through the short axis of the heart with a slice thickness of 10 mm and slices at a distance of 0 mm, 1 mm, 3 mm and 5 mm produced accurate left ventricular measurements with cardiac MRI. Measurements in the long axis of the heart resulted in a marked underestimation of myocardial mass; depending on slice intervals, there was an error between 13% and 20%. In vivo measurements in 35 subjects confirmed the effect of section alignment. Measurements in the long axis of the heart produced results of 139.9 +/- 31.7 g, significantly less than measurements in the short axis of the heart of 157.8 +/- 32.3 g.