Biomedical subjects

R D Müller

Publications and source records attributed to R D Müller.

At least 19 recordsLinked to original sources

PubMed2000

Successful interventional treatment of renal insufficiency caused by renal artery pseudoaneurysm with concomitant arteriovenous fistula.

Asymptomatic arteriovenous fistulae and pseudoaneurysms are common after renal biopsy. We present a patient with a single kidney and symptomatic pseudoaneurysm of the renal artery with concomitant arteriovenous fistula as a rare complication following surgical embolectomy. The patient developed renal insufficiency because of a significant degree of vascular steal caused by the fistula. Dialysis was performed for more than 6 months until the fistula was diagnosed. The fistula and the pseudoaneurysm were successfully treated by superselective arterial embolization with metallic coils. Renal function improved within the next 2 weeks and no further dialysis was necessary.

Aneurysm, False↗

PubMed1999

[CT densitometry for the grading of subcutaneous fibrosis after the photon-neutron therapy of malignant salivary gland tumors].

BACKGROUND: To evaluate alternative treatment regimen e.g. neutron therapy determination of treatment efficacy as well as side effects is important. Sensitivity of computed tomography (CT) in detecting changes of connective tissue after neutron therapy was examined. PATIENTS AND METHODS: In the course of their follow-up period (median 45 months) 12 patients with malignant salivary gland tumors who had postoperatively received neutron (1/12) or photon/neutron therapy (11/12) were examined by means of CT densitometry on 3 representative scans in the area of radiotherapy. In 3 ROI (regions of interest) in subcutaneous fatty tissue the density at the irradiated and the non-irradiated side was determined according to Hounsfield units (HU) and the average density was calculated. The average density of both sides was compared and correlated with the clinical grade of fibrosis according to LENT SOMA. RESULTS: All CT measurements (216 ROI, 18 ROI per patient) showed higher density levels on the irradiated side than on the non-irradiated side. The average density on the irradiated side was -57.7 +/- 4.7 HU and on the non-irradiated side -69.4 +/- 5.8 HU (p = 0.002). In 3/12 patients a clinical fibrosis was not seen; however, the relative density measured on the irradiated and non-irradiated side deviated by up to 8%. This could have been caused by minimal changes not being noticed by either patient and examiner. In patients with determined fibrosis Grade 1 (8/12) the relative density deviation was 4 to 39%. In 1/12 patients with determined fibrosis Grade 2 the relative density deviation was 50% (Figures 1a and 1b). Fibrosis Grade 3 and 4 did not occur (Table 1). CONCLUSIONS: Fibrosis is correlated with an increasing value of HU of the tissue density in CT. With the described method it is possible to graduate radiation induced subcutaneous fibrosis in correlation to the clinical fibrosis grade according to LENT SOMA. In the patients we examined subcutaneous fibroses after photon/neutron therapy were moderate. Especially in characterising subclinical or slight changes of connective tissue after radiotherapy computed tomography is of value.

Absorptiometry, Photon↗

PubMed1999

[3D-computed tomography for spatial arrangement of the cranial bones of the human fetus].

Aim of the study was to assess the value of in vitro three-dimensional computed tomography (3D-CT) as a new method for the depiction of the fetal skull. 3D-CT images of a fetal head of 24 weeks gestational age were generated with the implemented software on the basis of contiguous CT slices of 1 mm thickness. 3D-CT gave real three-dimensional information about morphology and spatial arrangement of the cranial bones. Using cutting and rotating procedures fast evaluation of all imaged ossified structures in arbitrary views without disturbing superpositions was possible, thus allowing easy identification and accurate description of the cranial bones and making isolated examinations of particular macroscopic sections of the specimens unnecessary. Advantages of 3D-CT over other evaluation techniques for the fetal cranium and its limitations are discussed. In conclusion, 3D-CT promises to be an effective tool for the investigation of fetal cranial development.

Fetus↗

PubMed1999

[Low-dosage dental CT].

PURPOSE: The intention of this study was to reduce patient dose during dental CT in the planning for osseointegrated implants. METHODS AND MATERIALS: Dental CTs were performed with a spiral CT (Somatom Plus 4, Siemens) and a dental software package. Use of the usual dental CT technique [1] (120 kVp; 165 mA, 1 s rotation time, 165 mAs; pitch factor 1) was compared with a new protocol (120 kVp; 50 mA; 0.7 s rotation time; 35 mAs; pitch factor 2) which delivered the best image quality at the lowest possible radiation dose, as tested in a preceding study. Image quality was analysed using a human anatomic head preparation. Four radiologists analysed the images independently. A Wilcoxon rank pair-test was used for statistic evaluation. The doses to the thyroid gland, the active bone marrow, the salivary glands, and the eye lens were determined in a tissue-equivalent phantom (Alderson-Rando Phantom) with lithium fluoride thermoluminescent dosimeters at the appropriate locations. RESULTS: By mAs reduction from 165 to 35 and using a pitch factor of 2, the radiation dose could be reduced by a factor of nine (max.) (e.g., the bone marrow dose could be reduced from 23.6 mSv to 2.9 mSv, eye lens from 0.5 mSv to 0.3 mSv, thyroid gland from 2.5 mSv to 0.5 mSv, parotid glands from 2.3 mSv to 0.4 mSv). The dose reduction did not lead to an actual loss of image quality or diagnostic information. CONCLUSION: A considerable dose reduction without loss of diagnostic information is achievable in dental CT. Dose-reducing examination protocols like the one presented may further expand the use of preoperative dental CT.

Humans↗

PubMed1999

[Optimization of beam filtering, kv-ma regulation curve and image intensifier entrance exposure rate to reduce radiation exposure in angiographic fluoroscopy].

AIM OF STUDY: Evaluation of radiation exposure and image quality during fluoroscopy using a new vascular X-ray system. MATERIAL AND METHODS: The measurements were made on an Integris V 3000 X-ray system with MRC tube and SpectraBeam technology (Philips Medical Systems, Hamburg). Entrance dose rates were measured with phantoms for the three fluoroscopy levels (1-3) which differed with regard to beam filtering and image intensiver entrance exposure rate. We evaluated 132 diagnostic and interventional angiographic studies. The angiographic investigators were asked to start with level 1 and to change to the next fluoroscopy level only in the case of insufficient image quality. RESULTS: Entrance dose rate is reduced by approx. 74% at fluoroscopy level 1 and by approx. 46% at level 2 relative to level 3 which is comparable to angiographic X-ray systems without MRC tube and SpectraBeam technology. Because level 1 ensured a sufficient image quality in 92% of the diagnostic and 60% of the interventional angiographic procedures a change to higher fluoroscopy levels was not necessary. CONCLUSION: Reduction of the intensifier exposure rate and the optimization of beam filtering enabled us to reduce the radiation exposure considerably. The procedure was well accepted by the angiographic investigators due to the diagnostically sufficient image quality of the fluoroscopy level 1.

Angiography, Digital Subtraction↗

PubMed1999

Prophylactic cranial irradiation in locally advanced non-small-cell lung cancer after multimodality treatment: long-term follow-up and investigations of late neuropsychologic effects.

PURPOSE: Relapse pattern and late toxicities in long-term survivors were analyzed after the introduction of prophylactic cranial irradiation (PCI) into a phase II trial on trimodality treatment of locally advanced (LAD) non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Seventy-five patients with stage IIIA(N2)/IIIB NSCLC were treated with induction chemotherapy, preoperative radiochemotherapy, and surgery. PCI was routinely offered during the second period of study accrual. Patients were given a total radiation dose of 30 Gy (2 Gy per daily fraction) over a 3-week period starting 1 day after the last chemotherapy cycle. RESULTS: Introduction of PCI reduced the rate of brain metastases as first site of relapse from 30% to 8% at 4 years (P =.005) and that of overall brain relapse from 54% to 13% (P <.0001). The effect of PCI was also observed in the good-prognosis subgroup of 47 patients who had a partial response or complete response to induction chemotherapy, with a reduction of brain relapse as first failure from 23% to 0% at 4 years (P =.01). Neuropsychologic testing revealed impairments in attention and visual memory in long-term survivors who received PCI as well as in those who did not receive PCI. T2-weighted magnetic resonance imaging revealed white matter abnormalities of higher grades in patients who received PCI than in those who did not. CONCLUSION: PCI at a moderate dose reduced brain metastases in LAD-NSCLC to a clinically significant extent, comparable to that in limited-disease small-cell lung cancer. Late toxicity to normal brain was acceptable. This study supports the use of PCI within intense protocols for LAD-NSCLC, particularly in patients with favorable prognostic factors.

Adult↗

PubMed1999

Prospective randomized study for an injection protocol for intravenous contrast media in abdominal and pelvic helical CT.

OBJECTIVE: To develop an injection protocol for intravenous administration of contrast media in abdominal and pelvic helical CT which provides optimal contrast enhancement of arterial and venous vessels. MATERIAL AND METHODS: For the study on a Somatom Plus 4 unit, a standard helical CT examination procedure of abdomen and pelvis consisted firstly of a native helical examination of the liver, a second one of the liver after intravenous injection of 120 ml nonionic contrast medium with a constant start delay of 50 s, and subsequently a third helical CT of the lower abdomen and pelvis. 125 patients were randomized for examination under different protocols, varying the injection flow from 2.0-4.0 ml/s and the time delay between the second and the third helical examinations from an additional 20-40 s. The efficacy of the contrast injection was checked by region of interest (ROI) measurements of HUs in aorta, inferior vena cava, and in femoral arteries and veins. The results were compared by t-test statistics. RESULTS: A slow flow rate of 2.0 ml/s led to a higher contrast enhancement in the aorta than a flow rate of 3.0 and 4.0 ml/s. The difference between 2.0 ml/s and 4.0 ml/s was statistically significant. In the inferior vena cava, a flow of 3.0 ml/s caused a better contrast than a flow of 2.0 ml/s or 4.0 ml/s, but the measurements did not reach statistical significance. The measurements in the femoral arteries and veins did not show any significant differences. Maximal enhancement in the pelvic vessels was achieved when the third helical examination was started immediately after the second one had ended. Adding any delay (20 s, 40 s) led to a reduced contrast in the pelvic vessels, with a significant reduction in aorta and femoral arteries. CONCLUSION: For routine abdominal and pelvic helical CT, we recommend an injection of 120 ml contrast medium with a flow rate of 3.0 ml/s. Contrast-enhanced examination of the liver should be started after 50 s, and examination of the lower abdomen and pelvis region should be performed without any further delay. This gives an appropriate contrast in the major vessels.

Abdomen↗

PubMed1999

Impact of CT in patients with sepsis of unknown origin.

PURPOSE: To evaluate the diagnostic relevance of CT in patients with sepsis of unknown origin. MATERIAL AND METHODS: Sixty-three consecutive intensive care patients with suspicion of an abscess and negative or inconclusive previous radiological examinations were included. CT was performed using the helical technique. A total of 45 abdominal and 38 chest examinations were evaluated. RESULTS: 5/38 examinations of the chest revealed the source of sepsis (pleural empyema 2, lung abscess 1, mediastinitis 1, retrosternal abscess 1). 7/45 abdominal CT examinations showed the source of sepsis (intraabdominal abscess 2, hepatic abscess 3, intestinal perforation 1, gangrenous colitis 1). CONCLUSION: CT is useful for the evaluation of patients with fever or sepsis without a known source. Due to the detection of a septic focus by CT, 19% of the patients in our study could be immediately referred to causal therapy as percutaneous drainage or surgery.

Abdominal Abscess↗

PubMed1999

SPIO-MR imaging versus double-phase spiral CT in detecting malignant lesions of the liver.

PURPOSE: To assess the diagnostic performance of superparamagnetic iron oxide MR (SPIO-MR) imaging compared with double-phase spiral CT in detecting liver metastases and hepatocellular carcinoma. MATERIAL AND METHODS: Thirty-eight patients with a total of 144 malignant lesions of the liver were examined by CT and SPIO-MR. After definition of a gold standard by a panel of experts, the patient images were randomized and presented to a blinded jury of 5 independent observers whose task was to identify as many lesions as possible. The results were tested for statistical significance using multifactorial analysis of variance (alpha=5%). RESULTS: SPIO-MR produced the highest detection rate and was significantly superior (p<0.05) to unenhanced MR imaging and double spiral-phase contrast-enhanced CT (DPS-CECT). Maximum performance in DPS-CECT was obtained during the portal venous contrast phase but was significantly inferior to SPIO-MR imaging. The scores for unenhanced CT and unenhanced MR were significantly lower than for the corresponding enhanced procedures. SPIO-MR imaging produced a higher incidence of false-positive findings (n=39). CONCLUSION: SPIO-MR produced a significantly better detection rate for malignant focal liver lesions compared with double-phase spiral DPS-CECT but was associated with a higher rate of false-positive findings.

Adult↗

PubMed1998

[Osteitis diagnosis in a group of angiology patients: a comparison of X-ray and nuclear medicine studies].

PURPOSE: Of the study was to examine the ranking of radiographs and bone scans in the diagnosis of osteitis. PATIENTS AND METHODS: 115 patients with arterial occlusive disease in stage Fontaine i.v. were referred for examination of the peripheral skeletal parts of the lower extremity. 126 radiographs and bone scans were taken. The time between the two examinations was 10 days maximum to enable direct comparison. Leukocyte scintigraphy was employed as gold standard. RESULTS: The sensitivity of radiographs was 47% with a specificity of 91%. Sensitivity and specificity of bone scans was 78% for both values. The positive predictive values for radiographs and bone scans were 88% and 85%, the negative predictive values were between 80% and 97%. CONCLUSION: In the majority of cases osteitis can be diagnosed with relatively inexpensive methods such as conventional x-rays and bone scans. Only in unclear cases further examinations such as leukocyte scintigraphy or magnetic resonance imaging should supplement the diagnosis.

Adult↗

PubMed1998

[MRI with supermagnetic iron particles versus double-spiral CT in identification of malignant liver lesions].

PURPOSE: The purpose of this study was to evaluate the efficacy of MRI with superparamagnetic iron oxide (SPIO) and double-spiral CT in the detection of liver metastases and hepatocellular carcinoma. METHODS: 38 patients with a total of 144 malignant hepatic lesions underwent CT and MRI. A panel of experts defined the gold standard. Five experienced judges performed independently blinded evaluation of the number of detectable lesions. Multifactorial variance analysis was used to determine the statistical significance. RESULTS: SPIO-MRI shows the highest rate of detection and is significantly superior to native MRI and native CT. The highest rate of detection by CT is shown in the portal-venous phase of contrast; nevertheless, the rate is significantly inferior to SPIO-MRI. In general, the native phases of CT and MRI are significantly inferior to the contrast phases of both. SPIO-MRI shows a higher rate of false positive findings. CONCLUSION: The time-consuming and cost-intensive SPIO-MRI significantly increases the rate of detectability for malignant liver lesions compared with double-spiral CT but it also increases the rate of false positive findings.

Adult↗

PubMed1998

[CT-controlled percutaneous drainage of intra-abdominal abscesses with basket catheters].

Today, CT-guided percutaneous drainage for intraabdominal abscesses of various origin and location is well accepted. With this method open surgery and its complications can be often avoided. We report results of such treatment in 47 patients with intraabdominal abscess formation. 66 "basket" catheters were placed into abscess formations of differing sizes and locations. 27 patients had developed abscess formation after surgery, in 2 patients abscesses after tumorembolisation were drained. In 18 cases there was no previous surgery. No complications occurred. Mean drainage time was 8.5 days. Surgical intervention was avoided in 34/47 patients. 9 of 47 patients received only percutaneous drainage. 25 of 47 patients required concomitant antibiotics for successful treatment. Antibiotics were selected according to bacterial culture with resistance determination. 13/47 cases required secondary surgery. About 80% of intraabdominal abscesses are curable with CT guided percutaneous drainage and systemic antibiotic medication. If a percutaneous drainage fails and signs of infection still remain, the procedure can be repeated. If secondary surgery after failing of percutaneous drainage should become necessary, the extent of the surgical intervention can be reduced. Surgery is necessary, if CT guided percutaneous drainage could not reach the abscess formation, if drainage failed or if an additional illness exists, which requires an operation.

Abdominal Abscess↗

PubMed1998

[Effect of collimation and pitch on radiation exposure and image quality in spiral CT of the thorax].

PURPOSE: The aim of the study was to optimize the scan parameters for spiral-CT of the thorax. METHODS: Using a Somatom AR-SP (Siemens AG, Erlangen) CT-unit, four different scanning protocols (collimation/table feed) were compared: A (5/10), B (10/10), C (10/15), D (10/20). High contrast resolution in the xy-plane and in the z-direction were investigated with special phantoms. Noise levels were measured using a water phantom, the radiation exposure of lung parenchyma was investigated using an Alderson-Rande-Phantom. An anthropoid chest phantom was scanned to compare the image quality of the four protocols. RESULTS: Protocol A showed the best resolution in the z-direction; the resolution in the xy-plane was equal for all protocols. Image noise in the center of the water phantom was 58 HU for protocol A and 40 HU for the other three. The following equivalent organ dose were measured for lung parenchyma: A 14 mSv, B 29 mSv, C 20 mSv, D 14 mSv. CONCLUSION: Scanning protocols with small collimation and a pitch of 2 are characterised by low radiation exposure and excellent resolution in the z-direction. These parameters seem to be most suitable for lung scanning.

Diagnostic Imaging↗

PubMed1997

Detection of radiographic findings in lung fibrosis using storage phosphor plates.

The aim of this work was to examine the influence of the filter kernel size on the detectability of differing radiological findings in interstitial lung disease. In 97 patients with confirmed pulmonary fibrosis chest radiographs were obtained with a filmscreen system of speed class 200 and with correspondingly exposed storage phosphorous plates. The size of the filter kernel used for the image postprocessing varied between sigma 5 and sigma 70. The detectability of interstitial lung changes was evaluated independently by eight readers on the basis of a defined rating system. The results were analysed using multifactorial analysis of variance with Scheffé test at a significance level of p = 0.05. Small kernel sizes (S 5, S 10) combined with high edge enhancement were only of benefit in the imaging of septal lines, but reduced the detectability of nodular and reticular structures. Good detail detectability of both micronodules and septal lines was obtained with a medium kernel size of sigma 40. Storage phosphor radiography utilizing the appropriate choice of postprocessing parameters provides equivalent image quality for evaluating interstitial lung changes compared with a modern filmscreen technique.

Female↗

PubMed1997

[Value of lung filter, asymmetric film-screen technique and digital storage screen radiography in diagnosis of coin lesion].

AIM: To evaluate the image quality of an asymmetric film-screen combination (a-FSC), a conventional screen-film combination (FSC) at speed class 200, a lung filter, and digital luminescence radiograms in detecting pulmonary nodules. METHODS: Detail perception studies were carried out with an anthropomorphic phantom. The image systems were exposed under standardised conditions with 125 kVp. The systems' perception efficiency was evaluated on the basis of 12.240 single observations with ROC analysis. RESULTS: In the overall evaluation the a-FSC and the filter achieved equally high assessments of 0.878 +/- 0.018 and 0.860 +/- 0.21 respectively (p > 0.05). The 200 speed FSC and the storage phosphor screen radiograms did not differ significantly. In the mediastinum all the tested systems were clearly superior to the 200 speed FSC (p < 0.05). In the lung fields on the other hand the 200 speed system was given a higher assessment of 0.866 +/- 0.026. The a-FSC had slight advantages over the lung filter and the digital imagining modes (p > 0.05). CONCLUSIONS: The a-FSC and digital luminescence radiograms provide significantly more diagnostic information in the mediastinum, together with high detail detectability in the lung fields and without requiring additional dosage.

Humans↗

PubMed1997

[Minimally invasive treatment of abscesses by CT-controlled drainage with a basket catheter system].

PURPOSE: To examine whether the percutaneous drainage of abscess formations by a new basket catheter system is usefull. MATERIAL AND METHODS: 58 patients with abscesses in different locations and origins have been treated by an interventional radiologic procedure. On the whole 77 basket-catheters were placed under CT-guidance into abscess formations of different size and localization. 36 patients developed an abscess after surgery, two patients achieved abscess drainage after embolisation of a tumor. In 20 patients the abscess was a complication of a septic infectious disease. RESULTS: Open surgery was avoided in 41/58 patients of these patients 9/41 received only percutaneous drainage and 32/41 patients suffering from illness were given antibiotic medication according to the resistogram in combination with percutaneous drainage. 17/58 patients required secondary surgery but with a lower risk because of the smaller abscess volume and the better clinical constitution after percutaneous drainage. CONCLUSIONS: A minimally invasive management of abscesses using a basket-catheter system is successful even in localisations deep inside the body and hard to reach. An irreversible catheter occlusion followed by the implantation of a new catheter system could be avoided in all patients.

Abdominal Abscess↗

PubMed1997

[CT angiography of the pulmonary artery in patients with bronchial carcinoma].

The aim of the study was to evaluate 3D computed tomography (3D-CT) for the visualization of tumor extent with respect to the infiltration of the pulmonary arteries in patients with locally advanced small and nonsmall-cell lung cancer. A total 61 examinations in 40 patients with bronchial carcinoma were performed with contrast-enhanced (150 ml injected with 4 ml/s after bolus tracking) 2 mm spiral CT (pitch 1.5, increment 1 mm) (Somatom Plus4, Siemens AG, Germany). Using the implemented software cine mode, surface shaded display (SSD), and maximum intensity projection (MIP), reconstructions of the pulmonary arteries and the tumors were generated. In comparison to conventional spiral thoracic CT, the optimized cross-sectional images of the mediastium represented a benefit with the technique described, and this can help to diagnose vessel infiltration and may therefore be of value for pre- and post-therapeutic staging in modern stage-adapted multimodality treatment programs.

Angiography↗

PubMed1996

Unsharp masking of low-dosed digital luminescence radiographs: results of a receiver operating characteristics analysis.

The extent to which the diagnostic performance of low-dosed storage phosphors can be improved by suitable image postprocessing was investigated. Storage phosphor radiographs and conventional 200- and 400-speed screen-film combinations of an anthropomorphic chest phantom with simulated nodules and linear structures were compared. The detection of test bodies was determined in a ROC analysis based on 16200 individual observations. The two analog screen-film systems did not differ significantly. As far as the storage phosphor radiographs are concerned, a higher diagnostic performance was achieved with a large filter kernel (S 40) whereas small filter kernels and edge-enhanced imaging modes reduced the detection of detail. The image quality of low-dosed storage phosphors is thus similar to high-amplification screen-film combinations if large filter kernels are used in postprocessing of the image.

Acrylic Resins↗