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Biomedical subjects

J Petersein

Publications and source records attributed to J Petersein.

At least 19 recordsLinked to original sources
PubMed2004

Length and angle measurements of the lower extremity in digital composite overview images.

We here introduce a digital scanning method for determining leg length and angles. The leg length and angle measurements, image quality and radiation dose were evaluated. A composite overview image was reconstructed from a series of individual images. In 45 overview images, the total leg length and the femoro-tibial angle were determined by two radiologists, and the inter- and intra-observer variability was examined in the light of the measured values as well as the subjective assessment of the image quality. A dose comparison was carried out with a series of conventional whole leg images. The mean standard deviation of the multiple measurements of leg length was 0.4 mm for researcher I and 0.5 mm for researcher II. The difference in the mean values of the measured leg lengths between the researchers was 0.3 mm. The mean standard deviation of the multiple measurements of the femoro-tibial angle was 0.1 degrees for both researchers. The difference in the mean values of the measured femoro-tibial angle between the researchers was 0.03 degrees. On average, the marks for the image quality awarded by researcher II with an average score of 2 were very significantly worse than those awarded by researcher I with an average score of 1.5. The mean entrance dose value determined was 0.16 mGy lower in the digital system (0.49 mGy) than that of the comparative conventional series (0.65 mGy). Where there is a large number of possible length and angle measurements, the proposed procedure offers the advantages of good image quality, digital image processing, measurements that are easy to perform, reproducible and accurate, and lower radiation dose, and it is superior to conventional whole leg images.

Adult↗
PubMed2004

Covered transjugular intrahepatic portosystemic stents maintain lower portal pressure and require fewer reinterventions than uncovered stents.

BACKGROUND: The purpose of this study was to evaluate the patency, functional and haemodynamic results of expanded-polytetrafluoroethylene (ePTFE)-covered transjugular intrahepatic portosystemic shunts in patients with liver cirrhosis. METHODS: Thirteen patients with an ePTFE-covered transjugular intrahepatic portosystemic shunt stent (TIPSS) were prospectively evaluated at 6 and 12 months and compared with matched controls with mesh-wire uncovered TIPSS. RESULTS: At 6 months, ePTFE-TIPSS showed a significantly lower porto-caval pressure gradient (PCPG) (9 (3-21) mmHg, P = 0.006), a lower rate of dysfunction (8% versus 54%, P = 0.03) and required fewer reinterventions (2 versus 13, P = 0.02); similar results were obtained after 12 months. This resulted in a reduction in the median cost for angiographic surveillance in the covered TIPSS group at 6 and 12 months (36% and 56% compared to the uncovered TIPSS group, P = 0.002), but total procedure-related costs were higher with the ePTFE-TIPSS (6 months: 3730 (3245-6759) versus 1850 (1466-5479) euro/patient; 12 months: 3945 (3460-6759) versus 2295 (1728-5694) euro/patient) due to the higher initial cost of the ePTFE-covered TIPSS. CONCLUSIONS: The insertion of ePTFE-covered TIPSS results in better maintenance of lowered portal pressure and fewer reinterventions in patients with liver cirrhosis. There is strong evidence that the use of ePTFE-TIPSS does not require regular surveillance to maintain primary patency, which may then improve cost-effectiveness.

Adult↗
PubMed2002

Results of the safety and efficacy of iobitridol in more than 61,000 patients.

We present results of a postmarketing surveillance study with iobitridol (Xenetix, Sulzbach, Germany) in more than 61,000 patients from 1996 until 2000. The purpose of this study was the assessment of safety and diagnostic efficacy of the non-ionic contrast agent iobitridol in the setting of a post-marketing surveillance study. Iobitridol (Xenetix) has been registered in Germany since 1996. Between 1996 and 2000 207 radiologists have documented in a questionnaire the routine use of Xenetix in 61,754 patients that have received Xenetix for diagnostic procedures. On each questionnaire parameters regarding demographic data, safety, and diagnostic efficacy were assessed. The data were statistically evaluated and analysed. The examination allowed for a diagnosis in 99% of cases. Image quality was rated as "excellent" or "good" in 89.8% of cases. In obese patients there was a significantly higher percentage ( p<0.001) of poor image quality. In 0.1% poor contrast was noted. Of patients, 28.8% had at least one risk factor, and 3.1% had three or more. Adverse events were noted in 2.3% of the examinations, but nearly half of them (1.1%) presented with "feeling of warmth" as the only symptom. Of adverse events, 0.2% were non-transient, and 1 patient died. In 0.2% of patients the procedure was stopped due to adverse events. In 0.9% of patients the causal relationship with the contrast agent was rated as probable (probable+possible=1.1%). The percentage of adverse events (excluding warmth) was independent of iodine concentration and of dose, and was higher in young patients. Xenetix is an efficient contrast agent for radiological procedures and is associated with a low rate of adverse events.

Contrast Media↗
PubMed2002

[Diagnostic value of secretin injections in dynamic MR pancreatography].

PURPOSE: To evaluate the effect of intravenous injections of secretin during MRP procedures. MATERIAL AND METHODS: From 1998 to 2001, 340 patients were examined with MRP. Depending on the native MRI/MRP diagnosis, 110 of them received an injection of secretin followed by multiple MRP's (every 2 minutes) up to 10 min after injection. Diagnosis included healthy persons (n = 23), pancreas divisum (n = 11), chronic pancreatitis (n = 68), and pancreatic tumors (n = 22); some patients had more than 1 diagnosis. Visibility of duct structures and amount of fluid filling of the duodenum after secretin injection were evaluated (dynamic examination) based on a five-point scale. Differences were tested statistically by means of Mc Nemar's test and ROC analysis. RESULTS: The visibility of the pancreatic duct could be increased significantly after secretin injection in all subgroups (p < 0.05). Statistically, it turned out not to be important at what time point after injection the MRP was taken. It was possible to evaluate the excretion rate of the pancreas. In healthy persons and those with pancreas divisum, the fluid filling of the duodenum was significantly higher than in those with chronic pancreatitis or pancreatic tumors. However, this finding alone did not suffice in differentiating between both groups (sensitivity 0.68 and specificity 0.59, respectively). CONCLUSION: The i. v. injection of secretin improves the ability of MRP to evaluate the pancreas by increasing the visibility of the pancreatic duct structures and provides a method to assess the excretion rate of the gland.

Adolescent↗
PubMed2002

[Image quality and detection of pathology by ultrasound: comparison of B-mode ultrasound with photopic imaging and tissue harmonic imaging alone and in combination].

PURPOSE: To determine the accuracy of photopic imaging (PI) in detecting pathology by ultrasound (US) and to assess the image quality in direct comparison with conventional B-mode ultrasound and tissue harmonic imaging (THI). MATERIAL AND METHODS: Fifty-two patients underwent US examination, among them 29 patients for abdominal assessment and 23 for otolaryngological assessment. A total of 208 freeze frames, 52 B-mode scans each with and without THI and 52 B-mode scans each with and without PI, were assessed by three readers, who determined the presence of pathology on a scale of 1 (definitely abnormal) to 5 (definitely normal). All 52 patients underwent US follow-up within six weeks. The results were confirmed by CT in 30 patients and by histology in five cases. Image quality and different color encodings of each technique were rated on a ranking scale of 1 (optimal) to 4 (poor). The different US techniques were compared in terms of image quality, diagnostic accuracy, and color encoding using McNemar's test and ROC analysis. RESULTS: The results for image quality were as follows: B-scan 3.9; THI 1.9; PI 2.8; and THI plus PI 1.5 (each p < 0.05). The following AUCs (Area under Curve, presence of pathology) were calculated: 0.925, 0.990, and 0.990 for B-mode US, THI, and PI, respectively (not significant), and 0.994 for THI plus PI (significant compared to B-mode scan). The different color encodings were rated as follows: reddish brown 1.6, gray 1.9, blue 3.1, and green 3.6 (each p < 0.05). CONCLUSION: For ultrasound examinations, PI in combination with THI improves the image quality and conspicuity of pathology.

Abdomen↗
PubMed2002

[Ultrasound at the bedside: does a portable ultrasound device save time?].

AIM: To prospectively determine whether the use of a portable ultrasound device results in a detectable reduction of the time required for acute ultrasound (US) assessment at the bedside. MATERIALS AND METHODS: A total of 125 patients underwent US at the bedside, among them 68 for abdominal assessment, 12 patients for chest or soft-tissue evaluation, and 45 patients with vascular disease. Five different US systems equipped with 3.5 MHz and 7.5 MHz wide-band transducers were compared in terms of overall examination time including transport, setting up and disassembling, switching on and off as well as initializing the device (but without writing of the report). The following ultrasound systems were used: the portable SonoSite 180 (SonoSite, Germany) as well as the mobile units Masters/Gateway 2000 (Diasonics, USA), Tosbee (Toshiba, Japan), PowerVision 7000 (Toshiba, Japan), and SONOLINE Elegra (Siemens AG, Germany). RESULTS: The portable ultrasound device significantly reduced the examination time per patient to a mean 16 +/- 4 min from 26 +/- 5 min for the mobile units (p < 0.05). This result was predominantly affected by the time required for switching on and initializing the device as well as the duration of positioning at the bedside and to a lesser extent by elevator waiting time. CONCLUSION: The overall time required for performing an ultrasound examination at the bedside can be considerably reduced if a portable device is used instead of a mobile system.

Abdomen, Acute↗
PubMed2001

Diagnosis of Heerfordt's syndrome by state-of-the-art ultrasound in combination with parotid biopsy: a case report.

The parotid gland is rarely affected by sarcoidosis (6% of all cases). If there is initial parotitis, and other major symptoms include fever, uveitis, or facial paralysis, the condition is referred to as Heerfordt's syndrome. The case presented here describes the diagnostic work-up and differentiation of swelling of the parotid gland by employing state-of-the-art ultrasound techniques in a 33-year-old patient with Heerfordt's syndrome. Color-coded duplex ultrasound demonstrated hypervascularization. Tissue harmonic and photopic imaging ultrasound additionally depicted hypoechoic, septated structural lesions of the glandular parenchyma with an optimized contrast. Since such structural changes are not a specific sonographic criterion for sarcoidosis, ultrasound-guided biopsy was performed for further clarification of the etiology of parotitis and for excluding lymphoma. In conclusion, state-of-the-art ultrasound with the option of obtaining a biopsy at low risk is a useful procedure for diagnosing unclear pathology of the parotid gland with rapid histological confirmation.

Adult↗
PubMed2000

[Value of negative oral contrast media in MR cholangiopancreatography (MRCP)].

PURPOSE: Evaluation of the use of a negative oral contrast material in MR cholangiopancreatography (MRCP). MATERIAL AND METHODS: We performed MRCP in single-shot technique (TSE, TR = 2800 ms, TE = 1100 ms, ETL = 64) in 38 patients before and 20-30 min after oral administration of 300-600 ml of a negative oral contrast material. The visualization ducts and details important for the diagnosis was evaluated in a blinded manner. Ductal diameters were measured. Both sets of images were evaluated qualitatively. RESULTS: The ductal diameters did not change after administration of oral contrast material. In 1/3 of all cases the ductal structures were superimposed by a high signal intensity of fluid in the gastrointestinal tract, especially in the tail of the pancreas. After administration of oral contrast material only in 3 patients could a complete visualization of the ducts not be achieved. In 5 cases, details relevant for the diagnostic decision could be seen only on post-contrast images. The anatomic orientation was not compromised by the absence of signal in the gastrointestinal tract. CONCLUSION: Negative oral contrast material should be given before performing a MRCP to provide non-superimposed visualization of the bile and pancreatic ducts. There is no negative influence of the oral contrast material on the diameter of the ducts.

Administration, Oral↗
PubMed2000

Focal liver lesions: evaluation of the efficacy of gadobenate dimeglumine in MR imaging--a multicenter phase III clinical study.

PURPOSE: To evaluate gadobenate dimeglumine (Gd-BOPTA) for dynamic and delayed magnetic resonance (MR) imaging of focal liver lesions. MATERIALS AND METHODS: In 126 of 214 patients, MR imaging was performed before Gd-BOPTA administration, immediately after bolus administration of a 0.05- mmol/kg dose of Gd-BOPTA, and 60-120 minutes after an additional intravenously infused 0.05-mmol/kg dose. In 88 patients, imaging was performed before and 60-120 minutes after a single, intravenously infused 0.1-mmol/kg dose. T1- and T2-weighted spin-echo and T1-weighted gradient-echo images were acquired. On-site and blinded off-site reviewers prospectively evaluated all images. Intraoperative ultrasonography, computed tomography (CT) during arterial portography, and/or CT with iodized oil served as the reference methods in 110 patients. RESULTS: Significantly more lesions were detected on combined pre- and postcontrast images compared with on precontrast images alone (P <. 01). All reviewers reported a decreased mean size of the smallest detected lesion and improved lesion conspicuity on postcontrast images. All on-site reviewers and two off-site reviewers reported increased overall diagnostic confidence (P <.01). Additional lesion characterization information was provided on up to 109 (59%) of 184 delayed images and for up to 50 (42%) of 118 patients in whom dynamic images were assessed. Gd-BOPTA would have helped change the diagnosis in 99 (47%) of 209 cases and affected patient treatment in 408 (23%) of 209 cases. CONCLUSION: Gd-BOPTA increases liver lesion conspicuity and detectability and aids in the characterization of lesions.

Adult↗
PubMed1999

MR imaging of the liver with Gd-BOPTA: quantitative analysis of T1-weighted images at two different doses.

This study evaluates the efficacy of gadobentate-dimeglumine (Gd-BOPTA) for enhancement of liver signal-to-noise ratio (SNR) and lesion-liver contrast-to-noise ratio (CNR) on T1-weighted spin-echo (SE) and gradient-recalled-echo (GRE) images at two different doses. Fifty patients with known or suspected liver lesions were examined at 1.5 T. T1-weighted SE (TR/TE 300/12 msec) and GRE images (TR/TE80/4.2 msec/flip angle 80 degrees) were obtained before and at 40-80 minutes and 90-120 minutes after administration of 0.05 or 0.1 mmol/kg Gd-BOPTA. Quantitative measurements of tissue signal intensity were performed at each dose. Liver showed significant enhancement after Gd-BOPTA on T1-weighted SE and GRE images (0.05 mmol: P < 0.05; 0.1 mmol: P < 0.001). The dose of 0.1 mmol/kg provided higher liver SNR than 0.05 mmol/kg. Mean liver SNR was higher on GRE than SE images (P < 0.0001). Lesion-liver CNR significantly increased on GRE images after 0.1 mmol (P < 0.05). There was a trend toward superiority of 0.1 mmol over 0.05 mmol/kg. GRE images were superior to SE images for pre- and post Gd-BOPTA lesion-liver CNR (P < 0.05). Our study suggests that Gd-BOPTA provides prolonged enhancement of liver SNR and CNR, that a dose of 0.1 mmol/Kg appears to be superior than 0.05 mmol/Kg, and that GRE techniques should be used in preference over SE techniques.

Adult↗
PubMed1999

[The use of automated speech recognition in diagnostic radiology].

PURPOSE: Applicability and benefits of digital speech recognition in diagnostic radiology were tested using the speech recognition system SP 6000. METHODS: The speech recognition system SP 6000 was integrated into the network of the institute and connected to the existing Radiological Information System (RIS). Three subjects used this system for writing 2305 findings from dictation. After the recognition process the date, length of dictation, time required for checking/correction, kind of examination and error rate were recorded for every dictation. With the same subjects, a correlation was performed with 625 conventionally written finding. RESULTS: After an 1-hour initial training the average error rates were 8.4 to 13.3%. The first adaptation of the speech recognition system (after nine days) decreased the average error rates to 2.4 to 10.7% due to the ability of the program to learn. The 2nd and 3rd adaptations resulted only in small changes of the error rate. An individual comparison of the error rate developments in the same kind of investigation showed the relative independence of the error rate on the individual user. CONCLUSION: The results show that the speech recognition system SP 6000 can be evaluated as an advantageous alternative for quickly recording radiological findings. A comparison between manually writing and dictating the findings verifies the individual differences of the writing speeds and shows the advantage of the application of voice recognition when faced with normal keyboard performance.

Germany↗
PubMed1999

Evaluation of liposomal contrast agents for liver CT in healthy rabbits.

RATIONALE AND OBJECTIVES: To evaluate the efficiency of two new liposomal contrast agents aimed at the reticuloendothelial system for liver CT in comparison to an extracellular contrast agent. METHODS: Two liposomal contrast agents (BR2 and BR21, respectively), containing free as well as encapsulated iomeprol at different concentrations, and commercially available free extracellular iomeprol were studied. In 60 experiments, the three contrast agents were tested at five different doses in rabbits. Intravenous injection was followed by dynamic CT studies over a period of 0 to 120 minutes (0 to 6 hours in 3 animals). A quantitative analysis of the enhancement in aorta and liver was performed. RESULTS: In healthy rabbits, the two liposomal contrast agents induced a significantly higher and more persistent increase in liver density at doses of > or = 1.5 mL/kg compared with the extracellular agent. The density enhancement induced by the two liposomal agents was dose-dependent and reached a maximum of +102 Hounsfield units (HU), compared with +87 HU for the extracellular contrast agent, at 2.0 mL/kg, without any appreciable increases at higher dosages. An adequate liver enhancement of at least +40 HU persisted for up to 90 minutes after injection of the liposomal contrast agents, compared with < 5 minutes after the extracellular agent. BR2 tended to provide a higher and more persistent enhancement than BR21. CONCLUSIONS: Liposomal contrast agents induce a more pronounced and much more persistent increase in liver density than conventional extracellular agents. Liposomes thus have the potential for optimizing CT examinations of the liver by providing a larger imaging window.

Animals↗
PubMed1999

Experimental study of X-ray mammography in a fluid bath: reduced radiation dose and improved detail resolution.

OBJECTIVE: To determine the effects on x-ray mammography of embedding the breast in a fluid bath. METHODS: A plexiglass phantom in the shape of a compressed breast was x-rayed in air and water with a mammography unit, and the radiation dose was measured by 20 thermoluminescence dosimeters placed in 20 representative positions on the surface of the phantom. Udders from slaughtered sheep as an animal model and phantoms were examined by mammography in identical positions surrounded by air and different fluids. The images were evaluated for detail resolution subjectively (animal model) and objectively (phantom containing quantifiable structures) by 6 and 15 blinded readers, respectively. The readers' results were analyzed and compared for visualization of the objects in air versus fluid. RESULTS: Mammographic examination in the fluid bath reduced the radiation dose and improved detail resolution in the rounded margin of the breast. Also, viewing conditions in the central region were improved as a result of the uniform optical density across the entire film area. CONCLUSIONS: Performing x-ray mammography in a fluid bath has advantages that make the technical realization of this method desirable.

Air↗
PubMed1999

[Interventional radiology--an option in minimally invasive therapy].

Percutan transluminal angioplasty (incl. implantation of stents) in the region of pelvic arteries and renal arteries, ct-guided facet joint injections/epidural injections and ct-guided block of lumbar sympathetic chain are some examples for the possibilities of interventional radiology as minimal invasive therapy. Indications, technique, clinical correlation, results and complications are described and discussed.

Angioplasty, Balloon, Coronary↗
PubMed1997

Colour-coded duplex sonography in the diagnostic assessment of vascular complications after kidney transplantation in children.

BACKGROUND: Vascular complications are a major cause of dysfunction or transplant loss in children. Arterial or venous occlusion, transplant renal artery stenosis (TRAS) and some arteriovenous (AV) fistula require rapid detection and prompt intervention. The present study was performed to determine the accuracy of colour Doppler sonography (CDS) in the early and late phase after renal transplantation and to correlate the results with angiographic and intraoperative findings. OBJECTIVE: CDS is the preferred imaging modality with a high diagnostic accuracy for follow-up of renal transplantation in children. The indication for angiography should be established on the basis of the CDS diagnosis. MATERIALS AND METHODS: In 87 children (mean age 10.9 years, range 2-17), 423 CDS examinations were performed after renal transplantation. Angiography was performed in 17 cases; surgery was necessary in 16 patients. RESULTS: CDS correctly identified 8/8 arterial or venous occlusions and 7/7 TRAS. The only false positive diagnosis of TRAS was due to misinterpretation of an iliac artery stenosis. Six AV fistulae were diagnosed by CDS. The overall positive predictive value of CDS was 94 % in this study. CONCLUSION: CDS is a noninvasive, non-radiation producing imaging modality with a high diagnostic accuracy. It is the method of choice in the assessment of vascular complications after renal transplantation in children.

Adolescent↗
PubMed1996

Liver. II: Iron oxide-based reticuloendothelial contrast agents for MR imaging. Clinical review.

Iron oxide-based compounds are a new class of MR contrast agents that have a wide range of clinical applications. The biodistribution and subsequent influence on the MR image depends on the particle size. Iron oxides can be used to increase contrast-to-noise ratio, facilitating the visibility of focal liver lesions. Other applications include blood-pool imaging and targeting the reticuloendothelial system and cell surface receptors.

Contrast Media↗