Central venous access ports placed by interventional radiologists: experience with 125 consecutive patients.

PURPOSE: To assess safety and function of central venous port systems implanted percutaneously in the interventional radiology suite. METHODS: One hundred and twenty-five consecutive ports in 123 patients were evaluated retrospectively. One hundred and twenty ports were implanted via the subclavian vein. RESULTS: Technical success was 100%. Fourteen patients (11.2%) experienced immediate procedural complications, all minor (pneumothorax 1.6%). During follow-up (4-343 days, mean service period 97.8 days), nine complications occurred, six of which were major. These were three port infections which led to hospitalization and port removal, one chamber penetration through the skin, and two port occlusions. Port removal as a result of complications was performed in six patients. Altogether, 20 complications occurred within a total of 11,056 days of service, which means 1.8 events per 1000 days of service. CONCLUSION: Percutaneous implantation of central venous port systems is safe and easy to perform. Complication rates of this study compare favorably with those of other radiological and surgical series.

Temporary vena cava filters and ultrahigh streptokinase thrombolysis therapy: a clinical study.

PURPOSE: To assess the efficacy of temporary vena cava filters in patients undergoing ultrahigh-dose streptokinase thrombolysis for iliocaval thrombosis and to determine therapy success and filter and therapy complications. METHODS: Forty-five patients were studied regarding extension and characteristics of thrombosis, duration, success, and complications of thrombolysis therapy, filter type, access route, pulmonary embolisms, and filter complications. RESULTS: Complete recanalization was achieved in 57% of cases. Filters were inserted predominantly via a transbrachial route. One fatal pulmonary embolism (2%) occurred 1 day after starting thrombolysis. No other pulmonary embolism was noted. Other complications were induced by thrombolysis alone (n = 12), thrombolysis and filter (n = 9), and filter alone (n = 11). CONCLUSION: Fatal pulmonary embolisms as a complication of ultrahigh-dose treatment of pelvic or caval thrombosis can not safely be prevented by the temporary vena cava filters currently available. Filter design needs to be improved.

Current practice of temporary vena cava filter insertion: a multicenter registry.

PURPOSE: To evaluate the current practice of temporary vena cava filter placement and its complications. MATERIALS AND METHODS: A multicenter registry was conducted from May 1995 until May 1997 using a standardized questionnaire. One hundred eighty-eight patients were evaluated. Patient characteristics, filter indications, filter characteristics, and complications were registered. RESULTS: Deep vein thrombosis was proven in 95.2% of the patients. Main filter indication was thrombolysis therapy (53.1%). Average filter time was 5.4 days. An Antheor filter was inserted in 56.4%, a Guenther filter in 26.6%, and a Prolyser filter in 17.%. Transfemoral filter implantation was slightly preferred (54.8%). Four patients died of pulmonary embolism (PE) during filter protection. Major filter problems were filter thrombosis (16%) and filter dislocation (4.8%). When thrombus was found in or at the filter before explantation, additional thrombolysis was performed in 16.7%, additional filter implantation in 10%, and thrombus aspiration in 6.7%; 4.8% of filters were replaced with permanent filters. DISCUSSION: Temporary vena cava filters are placed to prevent PE in a defined patient population. Despite their presence, PEs still occur in a small percentage. Problems of filter thrombosis and dislocation have to be solved. CONCLUSION: The results of this multicenter registry support the need for innovative filter design, as well as a randomized, prospective study.

Results of a prospective multicenter study for evaluation of the diagnostic quality of an open whole-body low-field MRI unit. A comparison with high-field MRI measured by the applicable gold standard.

OBJECTIVE: To evaluate the diagnostic quality of an open whole-body low-field MRI scanner compared to high-field scanners. MATERIALS AND METHODS: Over a period of 3 months, 401 patients with diseases of the kidney (n = 78), the shoulder (n = 122), the spine (n = 105) and the cerebrum (n = 96) were prospectively evaluated in four participating centers. They all underwent clinical evaluation, low-field and high-field MRI examination and surgical or follow-up confirmation of diagnosis. Clinical, histopathologic, high-field and low-field MRI diagnoses were recorded in standardized questionnaires that were centrally evaluated. Statistical evaluation comprised two parts: ROC analysis assessed accuracy of MRI and clinical diagnoses; furthermore rates of concordance of high- and low-field MRI diagnosis were calculated. RESULTS: We found no statistically relevant difference in high-field MRI diagnosis compared to low-field MRI diagnostic accuracy measured by clinical or surgical gold standard in three of the four regions examined; in cerebral examinations there was a small yet significant advantage for the high-field systems (P = 0.01). CONCLUSION: We conclude that the open low-field scanner we evaluated using clinical and surgical gold standard as reference is able to achieve comparable diagnostic accuracy compared to high-field scanners at lower costs and greater patient comfort. Limitations due to field strength (signal-to-noise ratio, resolution, scan time) seem to be relevant only in a very small number of cases that warrant high-field examination.

Local effect of three nonionic contrast media on the arterial blood flow velocity during iliofemoral arteriography.

RATIONALE AND OBJECTIVES: To investigate the influence of nonionic contrast media on the arterial blood flow velocity (BFV) during iliofemoral arteriography. MATERIALS AND METHODS: Iliofemoral arteriography with three contrast media--iopromide, iopamidol, and iodixanol--was carried out in 55 patients in a prospective manner. Hemodynamic changes were investigated using the change in the maximal systolic BFV in the dorsal artery of the foot and were recorded by simultaneous Doppler sonography. RESULTS: Comparable reductions in BFV were demonstrated for iopromide and iopamidol, but the iso-osmolar iodixanol produced no change in the maximal systolic BFV. The reduction in BFV by iopromide and iopamidol is attributed to a vasoconstrictive effect on the resistance vessels and is explained by a direct depolarization of the vascular smooth muscles with predamaged endothelium; the effect lasts for less than 1 minute. The time from the greatest change in BFV until the baseline value was achieved (recovery time) depended on the degree of vascular damage present. This can be explained by the inadequate compensation in circulatory regulation of patients with peripheral arterial occlusive disease. Iodixanol's lack of influence on BFV may result because its osmolality and chemotoxicity differ from those of iopromide and iopamidol. CONCLUSIONS: The peripheral hypoxemia observed in patients with arteriosclerotic vascular changes can be expected to increase through the vasoconstrictive effect of iopromide and iopamidol, whereas no such blood flow deficit is to be expected with the use of iodixanol. Nevertheless, the reduction in blood flow is of short duration and thus will probably not contribute significantly to this hypoxemia.

[The in-vitro evaluation of different embolectomy catheters for the treatment of acute pulmonary embolism]. / In-vitro-Evaluation verschiedener Embolektomiekatheter zur Behandlung der akuten Lungenembolie.

INTRODUCTION: Pulmonary embolism (PE) is one of the most common cardiovascular diseases and frequently causes death. As a rule, PE is treated with thrombolytic therapy or surgical thrombectomy. MATERIALS AND METHODS: In an in vitro model of the right lung, we tested four different percutaneous transluminal thrombectomy devices: a pigtail-catheter with an angled 3-cm (40 degrees) distal tip, the clot-buster, the hydrolyser catheter, and a modified hydrolyser. In 16 consecutive and repetitive experiments fresh thrombi were inserted and we evaluated the effectiveness of the system with respect to time, fragment size, reduction of the Miller score, and handling. RESULTS: Mean intervention times of the catheter systems were 23 min (pigtail), 14.4 min (modified hydrolyser), 13.8 min (clot-buster), and 10.8 min (hydrolyser). The maximum size of the produced fragments range from 0.5 to 3.5 mm by the pigtail and from 0.5 to 1 mm by the other systems. The Miller score reduction was from 14.4 to 2.8 (pigtail), 13.8 to 1.8 (clot-busters), 14.6 to 1.2 (hydrolyser), and 16.4 to 1 (modified hydrolyser). DISCUSSION: All four catheter systems were effective in the treatment of pulmonary embolism. The pigtail catheter is the most simple system but more time consuming and less effective in the fragmentation of emboli and reduction of the Miller score compared to the other three catheter systems. These systems were comparable in our model but especially the handling of the hydrolyser was encouraging.

[Comparative magnetic resonance imaging of renal space-occupying lesions with a high and low field MRI system]. / Vergleichende magnetresonanztomographische Darstellung renaler Raumforderungen an einem Hoch- und einem Niederfeld-MRT-System.

PURPOSE: A prospective study of the diagnostic accuracy and image quality of two MRI systems in the detection of renal tumors was investigated. MATERIALS AND METHODS: 34 patients with the clinical suspicion of a space-occupying renal lesion were examined by MRI with a low field (0.2 Tesla magnet) and a high field (1.5 Tesla magnet) for comparison. An "informed" and a "blind" observer evaluated all of the MR images. In addition, the signal-to-noise and contrast-to-noise ratios were evaluated as second quality parameters. RESULTS: In 29 cases the results could be compared with a confirmed release diagnosis. Diagnostic accuracy was comparable with both systems (Sensitivity for both observer on LF apparatus: 83%, HF apparatus: 81%) although the signal-to-noise and contrast-to-noise ratios were significantly poorer at low field. CONCLUSIONS: The low field system in comparable to the high field MRI for detection and differentiation of renal space-occupying lesions.

Clinical experience with temporary vena caval filters.

PURPOSE: To look at the benefits and complications of different vena caval filters inserted prophylactically. Three temporarily implantable caval filter systems were used in 67 patients. MATERIALS AND METHODS: Twelve Cook filters (six transjugular, six transfemoral), 11 Angiocor filters (one transjugular, 10 transbrachial), and 44 Antheor filters (three transjugular, four transfemoral, 37 transbrachial) were successfully implanted. In known iliac vein or caval thrombosis, the prophylactic filters were placed during thrombolytic therapy in 46 cases, surgery in 17 cases, thrombosis in pregnancy in three cases, and high-dose heparinization without lysis in one case. RESULTS: One patient had a fatal pulmonary embolism during treatment; seven thrombi were detected in the filter. Other complications were caused either by the underlying therapy alone (one fatal outcome of abdominal aorta aneurysmal surgery, two cases of cerebral hemorrhage, two cases of retroperitoneal hematomas, two cases of streptokinase fever reactions, one compartment syndrome, two cases of macrohematuria), by the combination of therapy and caval filter implantation (three cases of groin hematomas, three cases of arm hematomas), or by filter implantation alone (two cases of subclavian vein thrombosis, one catheter infection, one dislocation, one air embolism, one basket rupture). The bleeding complications were related to the aggressive thrombolytic therapy and would have occurred without filter implantation. CONCLUSION: Because temporary caval filters have no long-term complications per se, their use seems sensible as long as there are stringent indications, including the presence of iliac vein or caval thrombosis and risk of thrombus mobilization. The Antheor filter system was the most convenient system for implantation.

In vitro studies of temporary vena cava filters.

PURPOSE: To evaluate the clot trapping capacity of different temporary vena cava filters in a vena cava model. METHODS: A vena cava flow model was built using PVC tubing, a hemodialysis membrane and a pulsatile pump. Blood was imitated by a Dextran 40 solution. Five different temporary vena cava filters and two prototypes were tested using human thrombi. The mechanism of clot capture was observed. RESULTS: Decreasing rank order according to decreasing percentage of clots captured for the 21-mm diameter vena cava model was Cook (C) > Angiocor (A) > Cordis (CD) > Antheor (TF-6) > DIL for thrombi with a diameter of 3 mm and A > C > CD > TF-6 > DIL for 5-mm thrombi. In a cava with diameter of 28 mm, decreasing rank order was C > CD = A > TF-6 > DIL and C > CD = A > DIL > TF-6 for 3- and 5-mm thrombi, respectively. Two new prototypes, the TF-8 and TF-10 filters, achieved better results than the TF-6 filter and were in most conditions comparable to the A and CD filters. In most cases, thrombi were trapped between filter and cava wall. CONCLUSION: The vena cava flow model demonstrates significant differences in rates of clot capture (range 22%-98%) depending on cava diameter, thrombus size, and filter type.

MR-guided placement of a temporary vena cava filter: technique and feasibility.

The purpose of this paper was to investigate the feasibility of MR-guided insertion of a temporary vena cava filter on an open low-field imager. In vivo procedures were performed on four anesthetized pigs using a common nonferromagnetic temporary vena cava filter and a special prototype guidewire developed for vascular interventions guided by low-field MRI. Breath-hold spoiled gradient-echo sequences (fast low-angle shot [FLASH]) with flow compensation were used for position monitoring of the passively visualized intravascular devices. Using the described technique and equipment, all steps of the procedure were feasible in the MR unit. Practicability of the procedure seems to be sufficient for clinical purposes but was inferior compared to the conventional technique of filter placement.

[Angiography during interventional procedures with carbon dioxide (CO2) (carbo-angiography) in patients with increased contrast media risk]. / Interventionsbegleitende Angiographie mit Kohlendioxid (CO2) (Carboangiographie) bei Patienten mit erhöhtem Kontrastmittelrisiko.

Within the last 18 months we examined 130 patients with known complications or contraindications using iodinated contrast media for angiography by using carbon dioxide as contrast agent in digital subtraction angiography technique. These were diagnostic pelvis-leg angiographies (n = 106) with simultaneous consecutive interventional radiologic therapy in 68 cases. In 19 dialysis access fistulas 11 angioplasties were performed in the same session. In 5 cases of renal allografts no interventional radiologic therapy was necessary. For CO2 application an electronic controlled special injector was used. Carbon dioxide has a number of advantages: no adverse reactions, nonallergenic and can be used several times without increasing risks and is cost-saving. CO2 angiography is a sensitive method, for detection vessel wall processes below the diaphragm. It can replace conventional angiography.

[The angiography of kidney transplant arteries using carbon dioxide]. / Angiographie von Transplantatnierenarterien mit Kohlendioxid.

BACKGROUND AND OBJECTIVE: After renal transplantation hypertension occurs in 60-80% of patients, in 3-23% of them due to renal artery stenosis in the transplanted kidney. Angiographic assessment of the severity of the stenosis would best be done with a non-nephrotoxic contrast medium. We investigated the use of carbon dioxide, a bubble-forming contrast medium excreted via the lung, for its suitability in the angiography of the arterial system in the renal transplant. PATIENTS AND METHODS: In an uncontrolled series of observations on six patients with renal transplants and hypertension who were being treated with three or four antihypertensive drugs, the transplant's arteries were demonstrated with carbon dioxide, injected by Seldinger technique into the ipsilateral femoral artery, and the results recorded by subtraction angiography. RESULTS: The angiograms demonstrated postoperative kinked renal artery, a plaque in the external iliac artery, and a sharply angled origin of the external iliac artery in one case each, and three normal cases. CONCLUSIONS: Carbon dioxide is a suitable medium for demonstrating renal arteries in a transplanted kidney and is preferable to conventional contrast media for the angiographic diagnosis of possible renal artery stenosis.

Visualization of magnetic resonance-compatible needles at 1.5 and 0.2 Tesla.

PURPOSE: For two types of passively visualizable magnetic resonance (MR)-compatible needles, the size of susceptibility artifacts was investigated at 0.2 and 1.5 Tesla (T) and assessed regarding their suitability for needle visualization. METHODS: Phantom trials were performed using T1-weighted spin echo (SE), turbospin echo (TSE) and gradient echo (GE) sequences and different angles beta between the needles and the main magnetic field (B0). RESULTS: Depending on the needle angle beta and the applied pulse sequence, we found artifact diameters of 0-9.7 mm employing SE, of 1.7-9.4 mm employing TSE, and of 1.4-20.6 mm employing GE at 1.5 T. At 0.2 T, we found artifact diameters of 0-5.7 mm employing SE, of 0-6.3 mm employing TSE, and of 0-11.3 mm employing GE. CONCLUSION: Comparing artifact sizes at 1. 5 T and 0.2 T, low field strength is superior for passive visualization of the needles tested-especially if GE imaging is performed.

[A technic of MRT-guided abdominal drainage with an open low-field magnet. Its feasibility and the initial results]. / Technik der MRT-gesteuerten abdominellen Drainage an einem offenen Niederfeldmagneten. Durchführbarkeit und erste Ergebnisse.

PURPOSE: To test the practicality of MRT-aided drainage using an open low-field magnet and to report on the early clinical results. METHODS: So far seven patients have been treated (four subphrenic abscesses, two psoas abscesses and one pancreatic pseudocyst). The planning of the approach and catheter insertion were carried out under MRT control (Magnetom Open, 0.2 T). Subsequent treatment was controlled by CT and fluoroscopy. Initial puncture was carried out with a non-magnetic 18 gauge Chiba needle. The drainage catheter was introduced by Seldinger's technique in six cases and with a trocar in one patient. RESULTS: In all seven patients drainage could be started successfully. The design of the magnet and coils permitted adequate accessibility of the patient. There were no problems in visualising the puncture needle. Controlling the position of the catheter by MRT was, however, difficult. CONCLUSION: The first two steps in abscess drainage (planning the approach and inserting the catheter) can be carried out under MRT control. For further catheter control and observing the course of the disease we presently prefer CT or fluoroscopy.

[Carbon dioxide as an alternative contrast medium in peripheral angiography]. / Kohlendioxid als alternatives Kontrastmittel für die periphere Angiographie.

A closed gas pressure pistol was used in 50 patient CO2 angiography as a supplementary method to conventional injection with liquid contrast medium. These were diagnostic pelvis-leg angiographies (n = 36), therapeutic angiographies (n = 8), haemodialysis fistulas (n = 3), suspected stenosis of a renal transplant artery (n = 1) and suspected renal artery stenosis (n = 1). 246 renal angiography series were performed with CO2. Dosages varied in accordance with the imaged vascular area between 10 ccm;(shunt imaging) and up to 100 cm3 (pelvis-leg angiography), at pressures between 400 mbar in case of haemodialysis fistulas up to 2000 mbar in the pelvis-leg area. Short-term feeling of fullness and even nausea were accompanying symptoms in 4 patients. The image quality was slightly inferior to that of conventional contrast medium images due to an elevated signal-to-noise ratio. Injector-monitored CO2 angiographies enabled imaging of the distal aorta or of peripheral vascular sections, imaging of the upper extremity and presentation of kidney transplants in patients with a relative or absolute contraindication to iodised contrast media.

[Technique of MRT-guided core biopsy in the abdomen using an open low-field scanner: feasibility and initial clinical results]. / Technik der MRT-gesteuerten Stanzbiopsie im Abdomen an einem offenen Niederfeldgerät: Durchführbarkeit und erste klinische Ergebnisse.

PURPOSE: Due to high soft-tissue contrast and multiplanar imaging capabilities MRI is an interesting modality to perform image-guided biopsies. We checked on the feasibility of MR-guided core biopsies of abdominal masses with an open low-field scanner (0.2 Tesla; vertical field axis). METHODS: 9 patients underwent MR-guided biopsies of abdominal target lesions (6 focal liver lesions, two adrenal masses, one pelvic mass). Different MR-compatible core biopsy instruments were used (needle diameters 14G-18G). MR scans during the procedures were obtained applying T1-weighted gradient echo sequences suitable for breath-hold imaging. RESULTS: In each case, needle guidance was reliable, so that the biopsy instrument could be positioned correctly. Multiplanar imaging capabilities enabled even angled approaches to upper abdominal masses to be realized safely. The combination of magnet design and table design offered suitable access to the patient. CONCLUSION: Using an open low-field scanner, MR-guided core biopsies of abdominal masses are practicable.