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Biomedical subjects

J Kirchner

Publications and source records attributed to J Kirchner.

101 records · Page 6Linked to original sources
PubMedDate not supplied

First experiences in CT-guided percutaneous transhepatic biliary decompression by means of real-time CT fluoroscopy.

BACKGROUND: Computed tomographic fluoroscopy (CTF), also called real-time CT, is increasingly used in interventional radiology but has not yet been recommended to guide percutaneous transhepatic biliary decompression (PTBD). We report our early clinical experiences with CTF-guided PTBD. METHODS: Sixteen consecutive patients underwent PTBD under CTF guidance because of obstructive jaundice caused by malignant tumor (11 cases of carcinoma of the bile duct, four cases of pancreatic cancer, and one case of metastasis). CTF-guided PTBD was performed on a helical CT scanner and a surgical C arm. Main target parameters were the success and complication rates, the number of necessary punctures, the time needed for successful puncture of a suitable bile duct, and the patients' radiation exposure. RESULTS: CTF-guided punctures of the bile duct for PTBD were successful on the first trial in 10 cases; in six patients, two hits were necessary. The time needed to hit a suitable bile duct was 6-21 s (median = 13 s). Therefore, the radiation exposure (skin) was 27-94.5 mSv. The additional implantation and stenting of the bile duct by means of the surgical C arm was uneventful in 15 cases. In one case, only external drainage could be achieved. Complications did not occur. CONCLUSION: CTF enables good visualization of the most suitable duct for puncture. Therefore, subsequent recanalization seems to be easier than other methods.

Bile Duct Neoplasms↗
PubMedDate not supplied

A comparative study of CT fluoroscopy combined with fluoroscopy versus fluoroscopy alone for percutaneous transhepatic biliary drainage.

PURPOSE: We compared CT fluoroscopy (CTF) for the initial puncture of bile ducts with conventional fluoroscopic guidance in patients with malignant jaundice in whom percutaneous transhepatic biliary drainage (PTBD) was planned. METHODS: Forty consecutive patients were randomized to two study groups: group A underwent PTBD under CTF and fluoroscopic guidance, group B underwent PTBD under fluoroscopic guidance alone. CTF-guided PTBD was performed using a combination of a helical CT scanner of the latest generation and a mobile C-arm; conventional PTBD was performed under fluoroscopic guidance in the angiographic unit. End points of the study were the success (a puncture that enabled safe placement of a guidewire in a suitable bile duct) and the complication rate (hemobilia, bile fistula, biliary peritonitis), the number of punctures required, the time needed for successful puncture of a suitable bile duct, and the patient's radiation exposure. RESULTS: CTF-guided puncture of peripheral bile ducts suitable for PTBD was successful at the first attempt in 16 cases, under conventional fluoroscopic guidance, in only two cases. We found a significantly different number of punctures (1.2 in group A vs 2.9 in group B), a significantly shorter time for puncture in group A (mean 39 sec), but also a significantly higher skin exposure dosage in group A (mean 49.5 mSv surface dosage). There was no significant difference regarding the total procedure time. Only one complication occurred in group B (portobiliary fistula). CONCLUSION: CTF-guided initial puncture of bile ducts allowed a significantly reduced number of punctures and puncture times compared with puncture under conventional fluoroscopic guidance for placement of percutaneous transhepatic biliary drainage catheters.

Adult↗
PubMedDate not supplied

Better visualization of transbronchial biopsy using CT fluoroscopy.

PURPOSE: Computed tomography fluoroscopy (CTF) provides the capability for continuous CT imaging and has been increasingly used in interventional procedures. Our objective was to assess the usefulness of CTF in the monitoring of transbronchial biopsy procedures. METHODS: We evaluated nine patients in whom yield of "conventional" transbronchial biopsies had failed. CTF was performed on a Somatom Plus 4 Power scanner (CARE Vision CT, Siemens, Forchheim, Germany) using 120 kV, 50 mA at a frame rate of eight images per second on a matrix of 256 x 256. Image reconstruction was based on a partial scan with an acquisition time of 0.5 sec. The maximal time without interruption was 79 sec; after stopping for a few seconds a new period of 79 sec was available. The number of biopsies, procedure times, applied dose, and histologic results were documented. RESULTS: With CTF-guided transbronchial biopsy, the yield of the biopsies was improved. In seven patients biopsy yielded bronchial cancer; in one patient histopathologic examination showed tuberculosis. Only in one patient did CTF-guided transbronchial biopsy fail. The mean number of biopsies was four in each patient. Mean fluoroscopy time was 165 +/- 92 sec (range 111-272 sec) and mean procedure time was 800 +/- 302 sec (range 480-1081 sec). The applied dose ranged between 500 and 1224 mSv; the mean applied dose was 743 +/- 414 mSv. There were no fatal complications. CONCLUSION: Computed tomography fluoroscopy appears to facilitate visualization of transbronchial biopsy procedures, with the drawback of increased radiation exposure. To compare the "conventional" method versus CTF a randomized prospective study is necessary.

Aged↗
PubMedDate not supplied

First experiences in percutaneous arterial chemoembolization of malignant liver lesions by means of real-time CT fluoroscopy.

Computed tomography fluoroscopy (CTF) allows real-time display (continuous imaging) and has been increasingly used in interventional procedures. We wished to demonstrate the usefulness of CTF in chemoembolization of the liver. Twenty-one patients with primary or secondary malignant lesions of the liver underwent CTF-guided chemoembolization after angiographic positioning of a catheter in the hepatic artery. Embolization materials such as Lipiodol and mitomycin C were administered under continuous CT scanning. CTF led to a change of the method (correction of catheter position, application of norepinephrine) in nine of 21 cases. There were no fatal complications.

Aged↗
PubMedDate not supplied

CTF-guided puncture of an unenhanced isodense liver lesion during continuous intravenous injection of contrast medium.

CT fluoroscopy (CTF) facilitates guidance of percutaneous biopsies and other interventional procedures. We wished to demonstrate the usefulness of CTF for the puncture of an unenhanced isodense liver lesion during continuous injection of intravenous contrast medium. We performed CTF-guided puncture of a 2-cm lesion in the liver of a patient suffering from lung cancer. CTF enables puncture of liver foci even if they are unenhanced and isodense with the surrounding parenchyma.

Contrast Media↗
PubMedDate not supplied

Successful treatment of intimal hyperplasia in renal arteries by endovascular brachytherapy.

PURPOSE: The present study shows the possibility of preventing restenosis of renal arteries by endovascular brachytherapy. METHODS AND MATERIALS: We present a patient suffering from rapid restenosis of both renal arteries with decreasing renal function. Percutaneous transluminal angioplasty (PTA) and stent implantation were unable to stop hypertension and to stabilize renal function. Both renal arteries and the right pole artery were treated by endovascular brachytherapy in one session. RESULTS: Six months after intervention, intraarterial digital subtraction angiography (DSA) showed no evidence of recurrence, and the blood pressure remained normal without medical treatment. CONCLUSION: Endovascular brachytherapy can help to prevent restenosis in renal arteries. It is possible to treat both renal arteries and one pole artery in one session without any disadvantage.

Angiography, Digital Subtraction↗
PubMedDate not supplied

Universal and unique features of kinesin motors: insights from a comparison of fungal and animal conventional kinesins.

Kinesins are microtubule motors that use the energy derived from the hydrolysis of ATP to move unidirectionally along microtubules. The founding member of this still growing superfamily is conventional kinesin, a dimeric motor that moves processively towards the plus end of microtubules. Within the family of conventional kinesins, two groups can be distinguished to date, one derived from animal species, and one originating from filamentous fungi. So far no conventional kinesin has been reported from plant cells. Fungal and animal conventional kinesins differ in several respects, both in terms of their primary sequence and their physiological properties. Thus all fungal conventional kinesins move at velocities that are 4-5 times higher than those of animal conventional kinesins, and all of them appear to lack associated light chains. Both groups of motors are characterized by a number of group-specific sequence features which are considered here with respect to their functional importance. Animal and fungal conventional kinesins also share a number of sequence characteristics which point to common principles of motor function. The overall domain organization is remarkably similar. A C-terminal sequence motif common to all kinesins, which constitutes the only region of high homology outside the motor domain, suggests common principles of cargo association in both groups of motors. Consideration of the differences of, and similarities between, fungal and animal kinesins offers novel possibilities for experimentation (e. g., by constructing chimeras) that can be expected to contribute to our understanding of motor function.

Amino Acid Sequence↗
PubMedDate not supplied

[Intraocular pressure ten weeks after cataract surgery].

The effect of phacoemulsification and extracapsular cataract extraction on the intra-ocular pressure is analysed for several intra-operative factors. The mean intraocular pressure is significantly reduced ten weeks after the operation in comparison with the preoperative intraocular pressure. This reduction of the intraocular pressure is most significant for eyes with preoperative ocular hypertension and those eyes where leakage of the aqueous humour was evidenced during the immediate postoperative period.

Cataract Extraction↗