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Biomedical subjects

M Georgi

Publications and source records attributed to M Georgi.

At least 73 records · Page 4Linked to original sources
PubMed1997

[Bolus tracking and NaCl bolus in biphasic spiral CT of the abdomen].

PURPOSE: To optimise injection parameters in helical CT of the abdomen with individual bolus tracking and subsequent NaCl bolus injection. To investigate the effect of bolus tracking on image quality in the abdomen. METHODS: Patients were randomised into three examination protocols and underwent biphasic helical CT (Hi-Speed Advantage, GE). The effect of NaCl bolus on duration of aortic enhancement was investigated. Contrast enhancement in parenchyma and vessels was examined. The influence of body mass index, injection flow and contrast material volume on enhancement was evaluated. RESULTS: Subsequent injection of NaCl provided significant extension of contrast enhancement in the aorta. Optimal image quality for pancreas and abdominal arteries was achieved in the arterial phase and for liver, spleen, kidneys and abdominal veins in the portal venous phase. Body mass index, injection flow and contrast material volume showed a significant influence on the time intervals resulting from bolus tracking. CONCLUSION: Individual bolus tracking with subsequent injection of 20 ml NaCl bolus optimises intravenous contrast application.

Aorta, Abdominal↗
PubMed1997

[Goals, requirements and prerequisites of teleradiology. An assessment of current status].

Specific radiological requirements have to be considered for the realization of telemedicine. In this article the goals and requirements for an extensive introduction of teleradiology will be defined from the radiological user's point of view. Necessary medical, legal and professional prerequisites for teleradiology are presented. Essential requirements, such as data security, maintenance of personal rights and standardization, must be realized. Application-specific requirements, e.g. quality and extent of teleradiological functions, as well as technological alternatives, are discussed. Each project must be carefully planned in relation to one's own needs, extent of functions and system selection. Topics, such as acknowledgement of electronic documentation, reimbursement of teleradiology and liability, must be clarified. Legal advice and the observance of quality guidelines are recommended.

Forecasting↗
PubMed1997

[Clinical use of software-controlled x-ray tube modulation with "Smart-Scan" in spiral CT].

PURPOSE: The modulation of tube current during 360 degree-rotation for equalization of local differences in absorption is able to reduce patient exposure in spiral-CT. The impact on CT investigations of thorax, abdomen and pelvis and the influence of patient geometry within the slice on the decrease of tube current are evaluated. METHODS: 300 spiral-CT's were performed on a HiSpeed Advantage scanner (GE) using a software-triggered modulation of tube current ("Smart-Scan"). The local absorption was measured in the 100 central channels of 2 scoutiviews (lateral and a.p.) and used for anatomical adapted modulation. The reduction of exposure as well as the height and width of the body cross-section were measured in reference slices of 100 thorax, 100 abdomen and 100 pelvis examinations. RESULTS: The use of "Smart-Scar" enables a decrease of tube current of 7% in thorax, 6% in abdomen and 11% pelvis. There is a significant correlation between the height and width of body cross-section and the reduction of exposure for examinations of thorax and abdomen, but not of the pelvis. CONCLUSION: Independent of patient geometry the clinical use of "Smart-Scan" achieves the pelvis. Anatomical regions with an oval body cross-section show a decrease of x-ray tube current, too.

Adult↗
PubMed1997

[Ultra-rapid magnetic resonance tomography: a quantum leap in preoperative hepatobiliary diagnosis?].

The recent improvements in magnetic resonance (MR) imaging using the new ultrafast echo-planar technique for diagnosis of hepatobiliary lesions are outstanding. Besides the detection and preoperative evaluation of benign and malignant hepatobiliary tumors, angiography and cholangiography can be simultaneously performed using the techniques of MR angiography or MR cholangiography. Looking ahead, further advantages such as three-dimensional image reconstruction, no X-ray exposure, and short examination time, this MR technique will become the preferred diagnostic procedure for evaluating hepatobiliary lesions.

Bile Duct Neoplasms↗
PubMed1997

[Abdominal infect--what does radiologic diagnosis contribute? Required and superfluous tests].

Multiple radiological techniques can be employed to search for the source of abdominal sepsis. Plain abdominal film can give important direct or indirect information about the origin of sepsis. Computer tomography plays the most important role. Abscesses with their typical signs (gas within encapsuled extraluminal fluid, enhancement of membrane), as well as embolism and thrombosis, can be reliably detected as sources of sepsis. Magnet resonance imaging is an alternative for patients who would otherwise be regularly exposed to X-rays (e.g. in Crohn's disease). Dependent on the clinical setting studies of the gastrointestinal tract with water-soluble contrast media are indicated (e.g. for detection of fistulas or insufficiency of an anastomosis). Angiography and scintigraphic studies are not helpful in the search for the source of abdominal sepsis.

Abdominal Abscess↗
PubMed1996

[Transjugular intrahepatic portasystemic shunt. A new therapeutic method in portal hypertension].

Over the last three years, 53 patients underwent transjugular portosystemic shunting (TIPS). 49 patients were treated successfully (92.5%). Procedure-related morbidity (intention to treat) was seen in 11 patients (20.8%): encephalopathy (n = 5), sepsis (n = 3), right heart failure (n = 2) and progressive liver failure (n = 1). 30-day mortality rate was 13.2% (7/53); five of these patients were in stage Child-Pugh C, one patient in stage B, and one patient had a known coronary heart disease. 30-day rebleeding rate was 6.1% (3/49), but all these patients could be retreated successfully by radiological methods (PTA, embolisation, thrombolysis). Angiographic follow-up (mean six months) of 35 patients detected 30 (85.7%) haemodynamic relevant obstructions (stenosis of stent: n = 4, stenosis of hepatic vein: n = 15, stenosis of stent and hepatic vein: n = 5, occlusion of TIPS-shunt: n = 6). Secondary patency rate following percutaneous reintervention was 91.3%. All rebleedings in the follow-up (n = 7) were treated successfully by TIPS-revision. Five out of 12 patients (41.7%) with refractory ascites were treated successfully by TIPS (complete resolution of ascites after three months: n = 4, significant reduction of ascites: n = 1). We conclude that transjugular portosystemic shunt is an effective way of treating portal hypertension, but there is a need to develop methods to prevent the high incidence of shunt stenosis.

Adult↗
PubMed1996

Breath-hold MR imaging of focal liver lesions: comparison of fast and ultrasound techniques.

The performance of breath-hold MR imaging using two T2-weighted hybrid sequences (TSE, TGSE), two T2-weighted single-shot sequences (HASTE, EPI-SE), and one T1-weighted gradient-echo sequence (FLASH) was compared with a standard conventional T2-weighted SE sequence in 20 patients with focal liver lesions. Liver signal-to-noise ratio was highest for the FLASH sequence (54.3 +/- 8.3) and the HASTE (41.1 +/- 12.5) sequence, whereas the highest spleen-liver contrast-to-noise ratio was obtained by the TSE sequence (38.9 +/- 20.7). Lesion-liver CNR was highest with the TSE sequence (63.9 +/- 21.4). With both TSE and HASTE significantly (p < 0.01) more lesions were detected as compared with SE and EPI-SE sequences. Our results indicate that breath-hold TSE and HASTE sequences will eventually replace conventional T2-weighted SE techniques, due to their insensitivity to motion artifacts, superior lesion detectability and inherently short acquisition times.

Adult↗
PubMed1996

[Spiral CT angiography in stenoses of the middle cerebral artery].

INTRODUCTION: Transcranial Doppler ultrasonography (TCD) and magnetic resonance angiography (MRA) are well-established techniques for ascertaining intracranial obstructive artery disease. The short examination time required for additional helical CT angiography (CTA) allows quick management of emergency patients already undergoing native CT. However, today the ability of CTA to detect stenoses of the middle cerebral artery (MCA) has not been proven. To analyse the value of CTA in the classification of atherosclerotic disease 23 MCA stenoses confirmed by TCD and MRA were investigated. METHODS: CTA was performed on a Hispeed advantage scanner (GE) using a bolus injection of 70 ml KM and 40 ml NaCl with a flow rate of 2.5 ml/s, a thickness of 1 mm, a pitch of 1.5 and a 1 mm increment. CTA was presented as maximum intensity projection (MIP) and as multi-projection volume reconstruction (MPVR). A three-step classification of stenosis was compared with the results of TCD and MRA. RESULTS: Good opacification of the MCA was achieved in M1 and M2 segments in all patients. Classification of stenosis by CTA agreed with MRA and TCD in 14 cases; 7 stenoses were assigned to a lower classification by CTA. Two low-grade stenoses could not be proven by CTA. Although MIP and MPVR yield the same result in stenosis classification MPVR showed a sharper image quality. In contrast to MRA, veins were highly opacified in CTA. Artery and vein were sometimes superimposed, which had to be avoided by changing the projection angle. CONCLUSION: Medium- and high-grade MCA stenoses can be demonstrated by CTA quickly and reliably. Compared to MRA and TCD, CTA provides lower grading of stenosis.

Blood Flow Velocity↗
PubMed1996

[Functional magnetic resonance tomography during the activation of working memory].

AIMS: Functional magnetic resonance imaging was used in conjunction with a letter detection task for the study of working memory in 16 normal subjects. Because of movement artifacts, data from only 9 subjects were analysed. METHODS: In the activation task, subjects responded by pressing a button whenever any presented letter was the same as the second last in the sequence. In the control condition, the subjects had to respond to a fixed letter. Hence, the activation condition and the control condition differed only subjectively, i.e., regarding the task demand, whereas the stimuli and the type and frequency of response were identical. RESULTS: The activation condition produced significant activation in the dorsolateral prefrontal cortex (Brodmann's areas 10, 46, and 9). CONCLUSIONS: In contrast to experimental tasks previously used rather extensively to study the prefrontal cortex, the present paradigm is characterized by its simplicity, interpretability, and its ties to known neurophysiology of the frontal cortex.

Adult↗
PubMed1996

[The value of colloid scintigraphy and erythrocyte scintigraphy in detecting acute or intermittent gastrointestinal hemorrhages].

PURPOSE: In a retrospective analysis the diagnostic value of two scintigraphic methods was compared with each other. METHOD: 104 patients with acute or intermittent gastrointestinal haemorrhage were examined with 121 scintigraphic studies. We compared scintigraphic results with surgical findings, endoscopic results or final clinical diagnosis. We used two scintigraphic methods, colloid scintigraphy and in vivo/vitro red blood cell scintigraphy. RESULTS: Our scintigraphic findings reached a sensitivity of 72% and a specificity of 100%. We calculated a sensitivity of 68% for colloid scintigraphy and a sensitivity of 79% for red blood cell scintigraphy. The correct localisation of bleeding was successful in 52 (98%) cases. CONCLUSIONS: Our results demonstrate that red blood cell scintigraphy is the method of choice in detecting intermittent gastrointestinal hemorrhage. We believe that with new preparation kits for in vivo labelling red blood cell scintigraphy will become seriously competitive for the colloid scintigraphic method.

Acute Disease↗
PubMed1996

[Development of a clinical-radiological CD-ROM database for focal lesions of the liver].

PURPOSE: The development of a CD-ROM database for continuous acquisition and archiving of interesting radiologic cases is described. As a pilot study radiologic images of focal lesions of the liver were collected. METHODS: The database runs on a PC (80486 DX2, 66 MHz, 16 MB RAM), which is connected to the clinic network, a high quality x-ray scanner and a CD-ROM writer. Radiologic images can be inserted into the database either by scanner or by image transfer via network. The database is designed using Access 2.0. Well documented cases were chosen retrospectively, manipulated and archived. RESULTS: 308 images of 12 focal lesions with a capacity of 802 MB were stored on CD-ROM. Per case a storage capacity of 40-75 MB is necessary for image raw material, 15-25 MB are necessary for the postprocessed data. Spatial resolution is 190 dpi (3000 pixel/40 cm). Clinical data, radiological diagnosis coded by modified ACR index and a compressed icon of the images are stored on PC, the image data are stored on CD-ROM. 2.5 hours per case are needed for the complete acquisition, manipulation and archiving procedure, but improved hardware configuration can reduce the time significantly. CONCLUSION: The described database allows continuous archiving of interesting radiologic cases on PC. ACR index is suited for a quick search of a specific combination of radiologic images and diagnosis from different modalities.

Angiography↗
PubMed1996

Plasma and urine salsolinol in humans: effect of acute ethanol intake on the enantiomeric composition of salsolinol.

The tetrahydroisoquinoline (TIQ) salsolinol (SAL), a condensation product of dopamine and pyruvate or acetaldehyde, is one of the neuropharmacologically active alkaloids in mammals. Previous HPLC studies have shown that the R-enantiomer of SAL is largely predominant, or is the only enantiomer in the urine of healthy subjects, whereas the S-enantiomer was found predominant in the urine of alcoholics. An enzymatic pathway for SAL formation that is influenced by chronic alcohol intake was proposed. However, our analyses showed that the SAL detectable in human urine and plasma is racemic, at least in healthy subjects. No change of the enantiomeric distribution was observed after an acute alcohol ingestion (1 g alcohol/kg body weight). Using a new method for the resolution of the SAL enantiomers and gas chromatography mass spectrometry analysis, the SAL enantiomers were quantified in the urine and plasma of 24 subjects before and after the intake of alcohol. Special dietary conditions were observed to avoid interferences by the SAL of the foodstuff. Although the distribution of SAL enantiomers was not changed after alcohol intake, the total urinary SAL output and the plasma concentration of SAL were significantly influenced in different ways. Only five subjects showed a significant increase both in plasma SAL concentration and in the total urinary SAL output, whereas 19 subjects showed decreased or unchanged SAL levels after alcohol administration. Data also show that only the subjects with low baseline levels (mean of 0.148 ng SAL/ml plasma) tend to increase SAL levels after ethanol ingestion, which may imply some genetic basis for the response.

Adult↗
PubMed1996

Cerebrovascular reserve capacity in patients with occlusive cerebrovascular disease: assessment with dynamic susceptibility contrast-enhanced MR imaging and the acetazolamide stimulation test.

PURPOSE: To quantitatively assess cerebrovascular reserve capacity in patients with occlusive cerebrovascular disease. MATERIALS AND METHODS: In 21 symptomatic patients with occlusive cerebrovascular disease, magnetic resonance (MR) imaging was performed with a 1.5-T system. Before, during, and after a brief bolus injection of gadopentetate dimeglumine into the antecubital vain, a series of 32 rapid T2*-weighted gradient-echo images of two different sections were acquired simultaneously to measure the concentration-time-curves in the brain tissue and in the brain-feeding arteries. Principles of indicator dilution analysis were applied to compute regional cerebral blood flow (rCBF) and volume. Each patient underwent two examinations, the first before and the second after acetazolamide stimulation. RESULTS: In the asymptomatic hemisphere, a mean increase in rCBF value of 47.1% was observed after acetazolamide stimulation. In the affected areas of the symptomatic hemisphere, a statistically significantly reduced response to acetazolamide stimulation was found, indicating a severely compromised cerebrovascular reserve capacity. CONCLUSION: MR imaging with the described techniques provides quantitative information about the cerebrovascular reserve capacity in patients with occlusive cerebrovascular disease.

Acetazolamide↗
PubMed1996

[Septic portal vein thrombosis as a rare complication of Crohn disease with retroperitoneal abscess].

Portal vein thrombosis is a rare complication of inflammatory bowel disease and occurs particularly in patients with ulcerative colitis. This report describes a patient with known Crohn's disease since 1980 who developed retroperitoneal abscesses and subsequently a septic portal vein thrombosis. After 10 years of remission, clinical deterioration, jaundice, and fever occurred. An abdominal CT-study confirmed the ultrasonic presumptive diagnosis of two retroperitoneal abscesses close to the pancreas tail. Another CT, one week later, showed furthermore a portal vein thrombosis. Only by intensive care treatment was it possible to control the critical situation.

Abdominal Abscess↗
PubMed1996

[Diagnostic value of intravenous cholangiography within the scope of laparoscopic cholecystectomy].

In a retrospective study the accuracy of sonography and intravenous cholangiography (i.c.v.) in respect of pre-operative diagnostics before laparoscopic cholecystectomy was determined. Altogether 267 patients were examined by comparing sonography and icv results with those under both surgical and histopathological examinations. Ultrasound proved to be superior to i.c.v. detecting cholecystolithiasis in 99.4% versus 94.6%. The choledochus could be perceived in 81.0% by using ultrasound but in 93.6% by using i.c.v. In diagnosis of choledocholithiasis (CDL) i.c.v. proved to be more suitable. With this method 100% could be recognised whereas sonography showed CDL in 33.3%. Serious side effects caused by intravenous contrast media could not be observed during any i.c.v. examination. In our opinion i.c.v. is a valid and reliable method to detect CDL and should be used in addition to ultrasound in pre-operative diagnostics before laparoscopic cholecystectomy.

Adolescent↗
PubMed1996

[Radiologic medical desktop conferences--clinical evaluation of the KAMEDIN teleradiology system in routine practice of a radiologic institute].

KAMEDIN is a teleradiology project of "Deutsche Telekom". ISDN based image transfer, visualisation and online-presentation of digital radiological images is performed. In this study the suitability of the KAMEDIN-system has been tested in a clinical environment. The software has been adapted to the requirements of radiological image visualisation. During 6 months over 50 conferences took place with an average of 36 CT-slices per patient. The amount of time was approximately 10 min for conference preparation, 20 min for image transfer and 8 min for conferencing. Software problems occurred and were solved. Image quality on the monitor as well as online presentation including "simultaneous cursors" showed high performance and achieved high acceptance by the clinicians. Thus KAMEDIN is a useful teleradiology system, especially if the system is adapted to the requirements of radiology departments.

Computer Systems↗