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.

[The in-vitro evaluation of different embolectomy catheters for the treatment of acute pulmonary embolism]

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.

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.

[Comparative magnetic resonance imaging of renal space-occupying lesions with a high and low field MRI 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.

[Angiography during interventional procedures with carbon dioxide (CO2) (carbo-angiography) in patients with increased contrast media risk]

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.

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.

[The angiography of kidney transplant arteries using carbon dioxide]

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]

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]

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]

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.

[Indications and results of surgically treated, with temporary vena cava filter managed patients]

Heavily injured patients, patients who underwent operations on pelvis, hips, abdomen or malignoma surgery, as well as gynaecology patients suffering from malignoma or previous deep femoral vein thrombosis in connection with pregnancy or obesity are at risk to suffer from pulmonary embolism with potentially lethal course. In a retrospective study we evaluated the advantage of the prophylactic use of temporary vena cava filters and their side effects. The indications were 18 cases of surgery, with known iliacal vein or cava thrombosis, 3 cases of pregnancy thromboses, and 1 high-dose heparinisation after acute pulmonary embolism without lysis. Additionally a postoperative lysis therapy was performed due to a life-threatening pulmonary embolism in 1 patient. 1 Cook filter (transfemoral), 3 Angiocor filters (transbrachial), and 19 Antheor filters (3 transjugular, 5 transfemoral, 11 transbrachial) were implanted. In these patients no clinically visible pulmonary embolism occurred under therapy, 3 thrombi were detected in the filter. Complications were caused either by the underlying therapy alone (1 lethal outcome of abdominal aortic aneurysm surgery), by the combination of therapy and cava filter implantation (1 case of arm haematoma, 1 ascending thrombosis) or by filter implantation alone (2 cases of v. subclavia thrombosis, 1 dislocation, 1 basket rupture). Since temporary cava filters have no secondary complications per se, their use seems justified as long as there is strict indication including presence of iliacal vein or cava thrombosis and risk of thrombi mobilisation.

[In vitro studies on pulsed laser angioplasty in liquid and gaseous medium]

PURPOSE

In a vascular model the mechanisms of a pulsed dye laser working in a liquid and a gaseous environment was tested and documented by means of a high-speed camera.

METHODS

The pulse application (630 nm wavelength) on a target of calcified arterial plaque material was detected at intervals of 20 microseconds up to 800 microseconds total time.

RESULTS

In water the laser beam created a cavitation bubble which expanded from 0 to 450 microseconds from a radius 0 to 3 mm and collapsed afterwards. The average expansion velocity of the bubble was 80 m/s in the first 20 microseconds and the resulting velocity of the tube model wall was 10 m/s. Compared with gaseous atmosphere there was no bubble and consecutively no wall stress.

CONCLUSION

It is obvious that laser angioplasty causes wall stress and destruction of different vascular layers. This might be the initial stimulation for restenosis. In gaseous atmosphere laser angioplasty should be more protective.

[First experiences with temporary vena cava filters]

AIM

For prophylactic measures we used 3 different temporarily insertable vena cava filters.

MATERIAL AND METHODS

In 49 patients we inserted 12 Cook-filters (6 transjugular, 6 transfemoral), 11 Angio-cor-filters (1 transjugular, 10 transbrachial), 26 Antheor-filters (1 transjugular, 1 transfemoral, 24 transbrachial). 35 patients underwent a lysis therapy, 11 a major operation of the pelvis, and 3 patients a Caesarean section.

RESULTS

No patient suffered from a clinically significant pulmonary embolism after filter insertion, but complications occurred caused by the basic therapy (1 lethal abdominal aortic aneurysm operation, 1 cerebral bleeding, 2 retroperitoneal haematomas, 2 streptokinase fever reactions, 1 compartment syndrome, 1 macro-haematuria) or by therapy joined with the filters insertion (2 groin haematomas, 2 haematomas of the bend of the elbow, 2 subclavian vein thrombosis, 1 catheter dislocation, 1 infection, 1 air embolism, 1 break of a leg of the filter basket).

CONCLUSION

Temporary vena cava filters are highly efficient in preventing pulmonary embolism, but the side-effects show that they should only be inserted in patients with known deep vein thrombosis and a high risk treatment of the underlying disease.

[A new laser puncture guidance device for CT- and MRT-guided punctures of the trunk]

A stereotactic device was developed to facilitate CT- or MR-guided punctures of the body. The correct needle angulation is checked by the reflection of fan-shaped red and green laser beams upon the needle. Due to its principle of function and design the device has considerable advantages: The puncture angle can be controlled in three dimensions. The freedom of movement within the operation area will not be affected. The device does not have to be permanently installed and can be employed in MRI at any field strength. Furthermore, all kinds of puncture instruments can be used.

[Normal variation of arterial liver supply in mesenterico-celiacography]

Progress in operative techniques in surgery of the upper abdomen necessitates extensive preoperative diagnostic studies. Mesenterico-coeliacography along with CAT-SCAN form the basis for effective operative planning. In the angiography, the clinician is often confronted by variations in the arterial supply of the liver. These variations of the norm which are scarcely mentioned in anatomical textbooks must be carefully taken into consideration by the surgeon. In order to clarify the operative significance of these variations, we have conducted a retrospective study of the angiographies of the truncus coeliacus as well as of the arteria mesenterica superior. We found variations in 25.5% of 204 angiographies. The incidence of deviant and accessory hepatic arteries was 33.8% and of variations in the truncus coeliacus was 6.7%. These variations of the norm are discussed as to clinical and embryological aspects.

[Digital picture archiving, processing and communication in diagnostic imaging with a Siemens Network (SIENET): initial results]

The concept of Picture Archiving and Communication System (PACS) in digital imaging offers substantial advantages: better data security, faster access to archived images, simultaneous availability of images at different sites, minimal space demand for archive medium, retrospective image post-processing opportunities and lower costs resulting from reduced film consumption and length of stay. However, practical experiences concerning reliability and efficiency of real PAC networks in radiological departments have to be made yet in order to improve network structure, software design and hardware performance. The ongoing stepwise installation and test of a Siemens PACS (SIENET) at the Department of Radiology at the Medical University of Lübeck will support the introduction of PACS concept into radiological practice.

[Doppler ultrasound monitoring during vascular interventions]

Doppler ultrasound examination as diagnostic device in angiology yields only discontinuous information on flow velocities in vessels during insonation with hand-held probes. Continuous insonation and therefore determination of flow velocities in arteries are necessary to evaluate flow disturbances and changes of flow velocities during radiologic invasive interventions, i.e. implantation of stents, during percutaneous transluminal angioplasty therapy or local lysis. This modification of Doppler ultrasound examination is already used in neurosurgery for permanent monitoring of flow velocities in large brain vessels in one or both hemispheres during therapy. In our institute we developed a probe holder device to fix a miniature Doppler ultrasound probe (8-MHZ pulsed-wave probe) on the skin surface. Therefore continuous insonation during the manipulations is easy to realize. Information about complications such as occlusions, thrombi, emboli and changes in flow velocity is immediately present on the screen. We have monitored 40 patients during radiologic interventional therapy in arteries of the lower limb. Complications during the interventions were detected immediately and could be corrected.

[Densitometry in suspected preclinical osteoporosis: quantitative computerized tomography versus dual energy roentgen absorptiometry]

The bone mineral density of 85 patients with suspicion of a preclinical osteoporosis was measured at the lumbar spine by using quantitative computed tomography (QCT) in single-energy technique (SEQCT) and dual-energy technique (DEQCT) as well as by using dual-energy X-ray absorptiometry (DEXA). Additionally, the bone density of 63 of these patients was measured at the left femoral neck using DEXA. DEQCT und DEXA of the lumbar spine showed only a moderate correlation (R = 0.75) and differed considerably concerning the classification of the patients as normals or individuals with a mineral deficit when compared with age-matched normals (relative mineral deficit). The DEXA proved to be susceptible to degenerative alterations of the lumbar spine. Because of the extremely low dose of radiation and the good reproducibility the DEXA could nevertheless be recommended as a method for the long-time progress control especially for younger patients. SEQCT and DEQCT showed a very strong correlation (R = 0.98). The SEQCT with its lower dose of radiation should be sufficient for a long-time progress control and in many cases also for the initial diagnostics. Significant but only moderate correlations were found between the bone density at the femoral neck and the DEXA or DEQCT results (R = 0.68 respectively R = 0.63) for the lumbar spine, so that the linear regression did not render any useable approximations. Sufficiently exact information about the mineralization status of a certain skeletal site can only be obtained by direct measurement.

[MR tomography of acute pancreatitis: initial results]

Magnetic resonance imaging (MRI) was evaluated for its potential in assessment of acute pancreatitis compared to computed tomography (CT). 15 patients with acute pancreatitis were examined using a routine protocol including T1- and T2-weighted sequences and a fat-suppressed T1-weighted spin-echo sequence. Gadopentant-Dimeglumin (Gd-DTPA) was given. For comparison, plain and contrast-enhanced CT was performed prior to MRI. MRI proved to be superior to CT in detection of bleeding, duodenitis and ascites. MRI failed to detect concrements. These first results show that, considering the latest development in technology, MRI is not inferior to CT in diagnostic imaging of acute pancreatitis.

[DSA with mechanically injected carbon dioxide. Animal experimental results]

Carbon dioxide was used as an intra-arterial contrast medium by mechanical injection in 10 pigs. 127 angiographic examinations of 114 vascular territories were carried out and 93 were successful. A mechanism providing even gas volumes was chosen to obtain reproducible volume and pressures when using a compressible medium such as gas. Gas pressure is exponentially correlated with volume and volumes of 20-50 cm3 at 1000 mbar adequate for filling various infradiaphragmatic vascular areas. In parenchymatous organs, gas filling is seen only as far as third order arteries. The reason for this is escape of gas through preexisting arteriovenous fistulae into the efferent veins.

[Carbon dioxide as an irrigation medium for percutaneous angioscopy]

Since technical progress has allowed the development of small and flexible endoscopes, percutaneous, transluminal angioscopy promises to be a diagnostic and therapeutic tool. Nevertheless, the main problem is to obtain a satisfactory bloodless visual field. The saline solutions used for this purpose present problems with hypervolaemia, insufficient clearance, and decreased refraction. We investigated a CO2 application system for angioscopy that allows the reproducible injection of variable quantities of gas, pressure, and injection time. In 10 pigs undergoing angioscopy, CO2 was injected through a Swan-Ganz catheter under blockade of the distal aorta. Using a bifemoral approach, the application of gas and the blocking balloon were controlled by an automatic gas injector. The CO2 was injected through the tip of the catheter with a constant flow and a variable pressure and time. The angioscopy procedures were videotaped. With small volumes of carbon dioxide (approximately 50 cm3; 1000 mbar application pressure) a column of gas can be created which, unlike liquids, completely displaces blood from the vessels and allows for several minutes a bloodless inspection of the aorta and the side branches without blood mixture. Carbon dioxide application allows safe and successful percutaneous angioscopy under optimal conditions if the quantities of gas, pressure, and injection time are adjustable. The tested gas injection device fulfills these conditions.

[The laser-assisted balloon angioplasty of insufficient hemodialysis-access fistulae]

Patients with end-stage renal failure frequently develop venous stenoses or occlusions in their haemodialysis access fistulas caused by intimal fibrosis. A complete dilation with high pressure balloons up to 20 atm may be unsuccessful in such cases. We investigated two pulsed dye laser devices for the ablation of obstructions, which were not adequately treatable with a previous balloon angioplasty. From 11/90 to 4/92 a total amount of 154 PTAs of haemodialysis access fistulas were performed. In 23 of them additive laser angioplasty was necessary. 20 patients with Cimino fistulas presented 28 stenoses and two occlusions, whereas all the three patients with Goretex loops presented with occlusions. Two pulsed dye laser devices emitted at the wavelengths 504 nm (green) and 595 nm (red). Technical success was achieved in 22/23 cases, but clinical success was obtained in only 20/23 patients, due to two early reocclusions caused by thrombosis. 5 restenoses occurred two, three, 10, and twice 14 months after angioplasty with a mean follow-up period of 13.5 (5-18) months. Pulsed dye laser ablation in haemodialysis access fistula lesions due to intimal fibrosis greatly enriches radiological recanalisation techniques and is a valuable alternative to surgery if stand-alone balloon PTA fails.

Neural network approach for computer-assisted interpretation of ultrasound images of the gallbladder

Multi-formatted films of 90 ultrasound examinations of the gallbladder (stones 56 cases, sludge 20 cases, hydrops five cases, normal gallbladder nine cases) have been digitalized and stored in a personal computer. Image data of each examination was processed to extract a 19-dimensional vector that represents the essential diagnostic information of each examination. This vector was evaluated by three different classification algorithms: (1) classical nearest neighbor principle, (2) classical linear discriminant analysis, (3) multilayered backpropagation neural network. The correct classification rate was 64% (58/90) for the nearest neighbor principle, 97% (87/90) for the linear discriminant analysis, and 99% (89/90) for the backpropagation neural network. We conclude that, (1) automated classification of ultrasound images is possible for limited diagnostic problems, (2) a neural network approach can be used successfully for that goal, and (3) the efficiency of the more flexible neural network approach is comparable to large-scale classical methods.

Insufficient hemodialysis access fistulas: 18 months' experience in laser-supported dilation

Patients with end-stage renal failure disease frequently develop venous stenoses or occlusions in their hemodialysis access fistulas caused by intimal fibrosis. A complete dilation with high pressure balloons up to 20 atm may be unsuccessful in those cases. We investigated two new pulsed dye laser devices for the ablation of obstructions, which were not adequately treatable with a previous balloon angioplasty. From November 1990 to April 1992 a total of 154 percutaneous transluminal angioplasties (PTAs) of hemodialysis access fistulas were performed. In 23 of them an additive laser angioplasty was necessary. Twenty patients with Cimino fistulas presented 28 stenoses and two occlusions, and three Goretex loops presented all occlusions. Two pulsed dye laser devices emitting at 504 nm and 595 nm wavelength were tested. Technical success was achieved in 22/23 cases, but clinical success was obtained in 20/23 patients because two early reocclusions caused by thrombosis appeared. Five restenoses occurred 2, 3, 10, and in two cases 14 months after angioplasty with a mean follow-up period of 13.5 (5-18) months. Pulsed dye laser ablation in hemodialysis access fistula lesions due to intimal fibrosis is a valuable enrichment of radiological recanalization techniques and an alternative to surgery if stand alone balloon PTA fails.

[Thrombotic and thromboembolic occlusions of leg arteries and bypasses. Short-term versus long-term lysis]

Since thrombolytic therapy is less invasive than operative thrombectomy, it is often used as initial treatment for thrombotic or thrombo-embolic occlusions of lower limb arteries or by-passes. We compared four patient groups with acute and subacute occlusions: 1. 19 patients with occluded by-passes treated by rapid lysis using 15.5 (2.5-35) mg rt-PA. 2. 12 patients with by-pass occlusions treated with initial rt-PA in a dose of 6.5 (2.5-12.5) mg followed by prolonged lysis with 5.6 (2.5-10) x 10(6) units of urokinase. 3. 16 patients with arterial occlusions treated by rapid lysis with 15 (2.5-25) mg rt-PA. 4. 14 patients with arterial occlusions given 10.5 (2.5-60) mg rt-PA followed by overnight treatment with 5.9 (2.5-15) x 10(6) units of urokinase. For by-pass recanalisation, prolonged lysis overnight had a success rate of 83% (10/12) which was better than short term lysis with a success rate of 74% (14/19). Similar results were obtained in arterial occlusions with a success rate of 86% (12/14) compared with 69% (11/16). Long term lysis did, however, have significantly more complications. In about one-third of cases further procedures had to be used in addition to lytic therapy.

[The initial results of lumbar dual-energy x-ray absorptiometry (DEXA) compared to double-energy quantitative computed tomography (DE-QCT)]

Bone density measurements were performed on 51 patients with suspected osteoporosis. We used DE-QCT and DEXA. The methods were compared with regard to deviation from normal. In 29 of the 51 patients there was more than half standard deviation and in 12 of the 51 cases there was more than a full standard deviation.

Comparison of the cellular protein composition of aortic smooth muscle cells in vivo and in vitro by two-dimensional gel electrophoresis

Vascular smooth muscle cells are of major interest for the evaluation of atherosclerotic processes. By the use of two-dimensional gel electrophoresis and subsequent silver staining we investigated the protein expression of smooth muscle cells in the native thoracic aorta, immediately after enzymatic disaggregation, in subconfluent proliferating and in postconfluent nonproliferating primary cell cultures. Compared to the native thoracic aorta the protein composition of smooth muscle cells in cell culture is changed dramatically. Furthermore, significant differences in protein expression between proliferating and nonproliferating smooth muscle cells in cell culture were found.

Follow-up study of renal transplants by duplex Doppler and gray-scale ultrasound

In the early postoperative period after renal transplantation 388 follow-up ultrasound examinations were performed in 77 patients. Over a period of 18 months standardized duplex indices (resistive index, pulsatility index) and gray-scale parameters (parenchyma/sinus index; medulla/cortex index) were sampled. These data were correlated retrospectively with clinical and pathological diagnoses. To delineate the individual course of duplex and gray-scale indices during different transplant diseases we created a new parameter: the MID (maximal index difference) which is a result of the difference between the highest index during the phase of renal dysfunction and the lowest index during the phase of normal renal function. This MID, calculated for duplex indices and for the parenchyma/sinus index, indicated significant differences in the behavior of renal transplants during the four main diseases: interstitial rejection, vascular rejection, acute tubular necrosis and Cyclosporine A nephrotoxicity. Using the MIDs, a table of cut-off values was established, which enables to differentiate retrospectively these four transplant complications with a sensitivity of 84% and specificity of 81%. In our opinion consequent follow-up examinations with duplex and gray-scale sonography should be performed, enabling sonography to become a helpful diagnostic instrument in the monitoring of renal transplants.

Initial clinical experience with a new pulsed dye laser device in angioplasty of limb ischemia and shunt fistula obstructions

Selective plaque ablation with laser radiation at 405-530 nm in vitro has been reported. We investigated the possibilities of a new pulsed dye laser device for in vivo recanalization of arteries in ischemic lower limbs and stenoses/occlusions of arterio-venous hemodialysis shunt fistulae. A specially designed 9F or 7F multifiber catheter was used for treatment of 10 patients with lower limb artery obliterations and 11 patients with malfunctioning hemodialysis access fistulae (HAF). The recanalization technical success was 5/5 in the iliac arteries (IA), 4/5 in the superficial femoral arteries (SFA), and 11/11 in the HAF. Early re-occlusions occurred in one SFA and one IA, respectively, caused by very bad run-off. There was one clinically insignificant SFA perforation. Additional balloon angioplasty was considered necessary in 10/16 lesions. Mean ankle-arm index increased from 0.68 to 0.97. With two exceptions all HAF patients were re-integrated in the dialysis program. Pulsed dye laser angioplasty promises to be an effective and fast method for plaque ablation/debulking. The first clinical experience confirms previous in vitro results. In particular laser recanalization may become the method of choice for treatment of rigid HAF obstructions and it seems to be superior to vascular surgery or balloon angioplasty alone.

Post-traumatic migraine: chronic migraine precipitated by minor head or neck trauma

Minor trauma to the head or neck is occasionally followed by severe chronic headaches. We have evaluated 35 adults (27 women, 8 men) with no prior history of headaches, who developed recurrent episodic attacks typical of common or classic migraine following minor head or neck injuries ("post-traumatic migraine"-PTM). The median age of these patients was 38 years (range 17 to 63 years), which is older than the usual age at onset of idiopathic migraine. The trauma was relatively minor: 14 patients experienced head trauma with brief loss of consciousness, 14 patients sustained head trauma without loss of consciousness, and 7 patients had a "whiplash" neck injury with no documented head trauma. Headaches began immediately or within the first few days after the injury. PTM typically recurred several times per week and was often incapacitating. The patients had been unsuccessfully treated by other physicians, and there was a median delay of 4 months (range 1 to 30 months) before the diagnosis of PTM was suspected. The response to prophylactic anti-migraine medication (propranolol or amitriptyline used alone or in combination) was gratifying, with 21 of 30 adequately treated patients (70%) reporting dramatic reduction in the frequency and severity of their headaches. Improvement was noted in 18 of the 23 patients (78%) who were still involved in litigation at the time of treatment. The neurologic literature has placed excessive emphasis on compensation neurosis and psychological factors in the etiology of chronic headaches after minor trauma. Physicians must be aware of PTM, as it is both common and treatable.

Human vascular smooth muscle cells in culture: growth characteristics and protein pattern by use of serum-free media supplements

This study demonstrates that cultivation of vascular smooth muscle cells from human artery wall is possible under completely serum-free conditions. The effects of attachment factors on cell spreading and cell proliferation are described in detail as well as routine cultivation methods under serum-free conditions (clone cultures, cell migration, subcultivation by use of an exogenous trypsin inhibitor, cryopreservation and readaptation of cells). After a careful adaptation period, only two (BMS and Ultroser G) of the four commercially available serum-free media supplements tested were used successfully for a routine cultivation of the smooth muscle cells over several passages. With both supplements cell proliferation rates were comparable with those obtained in medium containing 10% fetal calf serum. The addition of platelet-derived growth factor or transferrin to serum-free cultures had no growth-stimulating effect. The addition of endothelial cell growth factor isolated from bovine brain caused a significant increase in proliferative activity of cells cultivated with BMS, but not with Ultroser G. Moreover, we report that under the serum-free culture conditions described here, the gamma-actin content of the cells is largely reduced (51% +/- 13% (means +/- SD) for cells cultivated in Ultroser G, and 12% +/- 4% (means +/- SD) for cells cultivated in BMS) when compared with cells cultivated under serum-containing conditions (gamma-actin content = 100%). The alpha-actin content was observed to be unaltered. Even after a careful readaptation of serum-free cultured cells to serum conditions, the gamma-actin content remained reduced.

[CT diagnosis of the elbow joint]

The normal anatomy of the elbow joint is described. Diverse pathologic joint alterations, e.g. fractures and dislocations, osteochondritis, inflammatory changes, and ulnar nerve lesion are demonstrated. Particular attention is paid to three-dimensional (3D-) reconstruction of demonstrable pathologic findings.

Cell constitution and characteristics of human atherosclerotic plaques selectively removed by percutaneous atherectomy

The Simpson atherectomy device used for the recanalization of severely stenosed peripheral arteries is able to collect plaque material which can be further characterized. This study reports histological, immunohistochemical and transmission electron microscopic findings on advanced human primary atherosclerotic plaques of peripheral arteries percutaneously removed by a Simpson atherectomy catheter. Material from stenosing plaques consisted of dense connective tissue with abundant amounts of concentrically arranged elastic fibers and lamellae. This meshwork contained numerous cells, often arranged in clusters and oriented with their longer axis parallel to the direction of blood flow. The vast majority of these cells could be easily identified as vimentin-positive and desmin-negative smooth muscle cells containing lipid deposits in the perinuclear region and numerous glycogen particles. Monocytes/macrophages were observed only very infrequently. Plaque tissue contained a range of smooth muscle cell phenotypes. Most of the cells were of an intermediate phenotype, i.e. sparsely filled with myofilament bundles at the cell periphery and a high amount of organelles such as mitochondria, rough endoplasmic reticulum and Golgi cisterns. An intact lining of pieces of intimal tissue with endothelial cells was not observed. Two-dimensional gel electrophoresis of plaque tissue showed the presence of alpha-, beta- and gamma-actin isoforms with a clear predominance of the beta-isoform.

[Analysis of dynamic CT curves in kidney transplants with rejection reaction and cyclosporin A poisoning]

The early differential diagnosis between transplant rejection and cyclosporin intoxication is often difficult, although it is important for treatment. We carried out dynamic CT on 48 occasions in patients with normal function, with acute tubular necrosis, rejection and cyclosporin A intoxication. Analysis of the time-density curve of the cortex showed significantly slower enhancement with cyclosporin A intoxication than during rejection. The peak and the arterial curve were also delayed in cyclosporin A intoxication. This evidence of reduced cortical perfusion during cyclosporin A intoxication can be explained by the results of modern pathophysiological studies. In principle, it is possible to distinguish between cyclosporin A intoxication and rejection by means of dynamic CT, but for its routine use the nephrotoxicity of the contrast medium must be taken into account.

[Follow-up of local lytic therapy of pulmonary emboli using DSA]

The series consisted of 30 patients with pulmonary emboli diagnosed by DSA. In 18 patients repeat DSA was performed using the central catheter which had been employed for the lytic therapy immediately after the end of treatment. Therapy was carried out from two to 14 days. Bleeding was observed in four of the patients. The final DSA showed complete recanalisation in five patients, partial recanalisation in 11 patients and no angiographic improvement in two.