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W Bautz

Publications and source records attributed to W Bautz.

At least 19 recordsLinked to original sources
PubMed2007

Evaluation of carotid artery stenosis with multisection CT and MR imaging: influence of imaging modality and postprocessing.

BACKGROUND AND PURPOSE: We prospectively evaluated the influence of different imaging techniques (time-of-flight MR angiography [TOF-MRA], contrast-enhanced MR angiography [CE-MRA], multisection CT angiography [CTA]) and postprocessing methods (maximum intensity projection [MIP], multiplanar reformation [MPR]) on carotid artery stenosis grading. MATERIALS AND METHODS: Fifty patients (34 men, 16 women) with symptomatic stenosis of the internal carotid artery were examined with a 16-section spiral CT and a 1.5T MR unit. Two MRA techniques were applied: 3D-TOF and CE-MRA. MPR was used for postprocessing with all modalities; MIP was used only with MRA. Four readers measured and calculated the percentage diameter stenosis independently according to NASCET criteria. The Wilcoxon test was used to measure interobserver variability, and the Friedman test was used to test the null-hypothesis of equality of the modalities. RESULTS: The hypothesis for global equality was rejected (P < .001). TOF-MRA and CTA assessed with MPR showed the highest concordance (difference, 0.6%; confidence interval [CI], -3.0, 4.3%), and CE-MRA with MIP and CTA showed the lowest concordance in stenosis grading (difference, 7.0%; CI, 3.4, 10.6%). MPR resulted in lower degrees of stenosis than MIP for both MRA sequences, although not statistically significant (CE, -3.0%; CI, -6.6, 0.6%; TOF, -2.2%; CI, -5.8, 1.4%). When only studies with good or excellent image quality were considered, the differences decreased, but the trends remained. CONCLUSION: Stenosis grading is dependent on the examination method and postprocessing technique. CTA and TOF-MRA evaluated with MPR revealed highest concordance.

Aged↗
PubMed2006

Evaluation of low-cost computer monitors for the detection of cervical spine injuries in the emergency room: an observer confidence-based study.

BACKGROUND: To compare the diagnostic value of low-cost computer monitors and a Picture Archiving and Communication System (PACS) workstation for the evaluation of cervical spine fractures in the emergency room. METHODS: Two groups of readers blinded to the diagnoses (2 radiologists and 3 orthopaedic surgeons) independently assessed-digital radiographs of the cervical spine (anterior-posterior, oblique and trans-oral-dens views). The radiographs of 57 patients who arrived consecutively to the emergency room in 2004 with clinical suspicion of a cervical spine injury were evaluated. The diagnostic values of these radiographs were scored on a 3-point scale (1 = diagnosis not possible/bad image quality, 2 = diagnosis uncertain, 3 = clear diagnosis of fracture or no fracture) on a PACS workstation and on two different liquid crystal display (LCD) personal computer monitors. The images were randomised to avoid memory effects. We used logistic mixed-effects models to determine the possible effects of monitor type on the evaluation of x ray images. To determine the overall effects of monitor type, this variable was used as a fixed effect, and the image number and reader group (radiologist or orthopaedic surgeon) were used as random effects on display quality. Group-specific effects were examined, with the reader group and additional fixed effects as terms. A significance level of 0.05 was established for assessing the contribution of each fixed effect to the model. RESULTS: Overall, the diagnostic score did not differ significantly between standard personal computer monitors and the PACS workstation (both p values were 0.78). CONCLUSION: Low-cost LCD personal computer monitors may be useful in establishing a diagnosis of cervical spine fractures in the emergency room.

Attitude of Health Personnel↗
PubMed2006

Retrospective interactive rigid fusion of (18)F-FDG-PET and CT. Additional diagnostic information in melanoma patients.

AIM: This study investigates whether interactive rigid fusion of routine PET and CT data improves localization, detection and characterization of lesions compared to separate reading. For this purpose, routine PET and CT scans of patients with metastases from malignant melanoma were used. PATIENTS, METHODS: In 34 patients with histologically confirmed malignant melanoma, FDG-PET and spiral CT were performed using clinical standard protocols. For all of these patients, gold standard was available. Clinical and radiological follow-up identified 82 lesions as definitely pathological. Two board-certified nuclear medicine physicians and two board-certified radiologists analyzed PET and CT images independently from each other. For each patient up to 32 anatomical regions (24 lymph node regions, 8 extranodular regions) were systematically classified. Discordant areas were interactively analyzed in manually and rigidly registered images using a commercially available fusion tool. No side-by-side reading was performed. RESULTS: Image fusion disclosed that the evaluation of the PET images alone led to a mislocalization in 26 of 91 focally FDG enhancing lesions. The overall sensitivities of PET, CT, and image fusion were 85, 88, and 94%, respectively; the overall specificities of PET, CT and image fusion were 98, 95 and 100%, respectively. Image fusion exhibited statistically significant higher specificity values as compared with CT. Ten definitely malignant sites were false-negative in CT, but could be detected by PET. On the other hand, twelve metastases were false-negative in PET, but could be detected by CT. These included two lesions, which had a clear correlate on the PET image when the fused images were evaluated. On the whole, registration of the PET and CT images yielded additional diagnostic information in 44% of the definitely malignant lesions. CONCLUSION: Retrospective image fusion of independently obtained PET and CT data is particularly valuable in exactly localizing foci of abnormal FDG uptake and improves the detection of metastases of malignant melanoma.

Adult↗
PubMed2005

Clinical evaluation of bone-subtraction CT angiography (BSCTA) in head and neck imaging.

Fifty-one patients were examined with bone subtraction CT angiography (BSCTA). Data were acquired on 4-and 64-slice spiral CT systems. The post-processing method is based on fully automatic registration of non-enhanced and contrast-enhanced CT data and subsequent selective bone removal. Vascular structures and brain tissue are retained with the original CTA noise level. Image quality and delineation of the pathologic process were assessed and artifacts introduced by the bone removal process recorded. The bone subtraction algorithm worked successfully in all examinations. The processing time was 6 min on average. Image quality was rated excellent in 20 (39%), good in 26 (51%) and acceptable in 5 (10%) patients. Ophthalmic arteries were visible in 12 (24%) patients bilaterally, in 13 (25%) patients unilaterally and in 26 (51%) patients at least at the origin. BSCTA improved visualization of the infraclinoid ICA and the vertebral arteries. The depiction of stenosis of the extracranial ICA and supraclinoid aneurysms was not significantly improved. In patients with suspicion of sinus thrombosis, BSCTA and conventional CTA yielded similar results. To conclude, BSCTA improves the visualization of vessels with close contact to bone and can improve the diagnostic accuracy and therapy planning of infraclinoid aneurysms.

Adult↗
PubMed2005

[Clinical results of digital mammography].

Digital mammography is the technology of the future in breast diagnosis. This article provides an overview of all digital mammography units admitted by the Food and Drug Administration (FDA), results of clinical studies, soft copy reading, CAD (computer aided detection), and presents an overview on possible further developments. It is obvious that clinical results are equivalent to conventional screen film mammography and digital mammography.

Breast Neoplasms↗
PubMed2005

[Godfrey N. Hounsfield and his influence on radiology].

On August 12, 2004 Sir Godfrey N. Hounsfield died at the age of 84 years. Computed tomography, which he developed, has been the most important invention in radiology since the discovery of X-rays; it revolutionized the medical diagnostic undisputedly. The essay gives an insight into the personality and the achievments of G. N. Hounsfield as well as the evolution of computed tomography of the classical sequential scanning via single to the current multislice spiral technique. The perspectives of computed tomography are shown.

England↗
PubMed2005

[Digital mammography with high-resolution storage plates (CR) versus full-field digital mammography (CCD) (DR) for microcalcifications and focal lesions -- a retrospective clinical histologic analysis (n = 102)].

PURPOSE: To determine the diagnostic accuracy of microcalcifications and focal lesions in a retrospective clinical-histological study using high-resolution digital phosphor storage plates (hard copy) and full-field digital mammography (hard copy). MATERIALS AND METHODS: From May 2003 to September 2003, 102 patients underwent digital storage plate mammography (CR), using a mammography unit (Mammomat 3000 N, Siemens) in combination with a high resolution (9 lp/mm) digital storage phosphor plate system (pixel size 50 microm) (Fuji/Siemens). After diagnosis and preoperative wire localization, full-field digital mammography (CCD) (DR) was performed with the same exposure parameters. The full-field digital mammography used a CCD-detector (SenoScan) (Fisher Imaging) with a resolution of 10 Ip/mm and a pixel size of 50 microm. Five investigators determined the diagnosis (BI-RADS I - V) retrospectively after the operation from randomly distributed mediolateral views (hard copy reading). These results were correlated with the final histology. RESULTS: The diagnostic accuracy of digital storage plate mammography (CR) and full-field digital mammography (CCD) (DR) was 73 % and 71 % for all findings (n = 102), 73 % and 71 % for microcalcifications (n = 51), and 72 % and 70 % for focal lesions (n = 51). The overall results showed no difference. CONCLUSION: Our findings indicate the equivalence of high-resolution digital phosphor storage plate mammography (CR) and full-field digital mammography (CCD) (DR).

Adult↗
PubMed2005

[Interventional methods in diagnostics of the breast -- a new vacuum biopsy system for the breast in routine clinical practice].

AIM: To evaluate the diagnostic potential of the new vacuum-assisted method VacuFlash (VF) in clinical routine of breast diagnostics. METHOD: From april 2002 to march 2003, the new sonographically guided vacuum-assisted system VacuFlash was used in 75 patients with a BI-RADS 5 lesion (analogue). The patients were aged between 31-75 yrs (median: 51 yrs), the size of the lesions measured 8-33 mm (median: 14 mm). 5 specimens were taken from each lesion. RESULTS: In 69 of the 75 lesions (92 %, respectively), malignancy was confirmed. In 8 lesions (8 %, resp.), we found a benign histology, confirmed by consecutive surgery. CONCLUSION: The new vacuum-assisted device VacuFlash is a technically perfected and applicable diagnostic method. Especially in the view of the cost it has to be compared with high-speed core cut biopsy, the hand-held Mammotome system and open surgical biopsy. High-speed core cut biopsy seems to be the standard procedure in diagnostic percutaneous breast intervention to clarify sonographically detected breast lesions.

Adult↗
PubMed2005

Attenuation correction of SPECT images based on separately performed CT: Effect on the measurement of regional uptake values.

AIM: A new software approach uses separately acquired CT images for attenuation correction after retrospective fusion with the SPECT data. This study evaluates the effect of this CT-based attenuation correction on indium-111-pentetreotide-SPECT images. METHODS: Indium-111-pentetreotide-SPECT imaging using a dual-head gamma camera e.cam (Siemens Medical Solutions, Erlangen, Germany) as well as separate spiral computed tomography (CT) was performed in 13 patients. After fusion of SPECT and CT data, the bilinear attenuation coefficients were calculated for each pixel in the CT image volume using their Hounsfield unit values and attenuation-corrected images were reconstructed iteratively (OSEM 2D). Regions of interest (ROIs) were drawn on 24 suspicious foci and background, and target to background ratios were calculated for corrected (TBAC) and uncorrected (TBNAC) images. The shortest distance from the centre of the lesion to the surface of the body (DS) was measured on the corresponding CT slice. Furthermore, ROIs were drawn over the rim and the centre of the liver. Ratios of hepatic count rates for corrected (LRAC) and uncorrected (LRNAC) images were also compared. RESULTS: In lesions located more centrally, TBAC was up to 52% higher, whereas in peripherally located lesions, TBAC was up to 63% lower than TBNAC. The TBAC/TBNAC quotient was linearly correlated with DS. In the liver, attenuation correction resulted in a 35% increase of LRAC compared with LRNAC. CONCLUSIONS: Attenuation correction of SPECT images performed by separately acquired CT data is quick and simple. It improves the contrast between target and background for lesions located more centrally in the body and improves homogeneity of the visualisation of tracer uptake in the liver.

Adult↗
PubMed2005

[Anatomical accuracy of lesion localization. Retrospective interactive rigid image registration between 18F-FDG-PET and X-ray CT].

UNLABELLED: The aim of this study was to evaluate the anatomical accuracy and reproducibility of retrospective interactive rigid image registration (RIR) between routinely archived X-ray computer tomography (CT) and positron emission tomography performed with 18F-deoxyglucose (FDG-PET) in oncological patients. METHODS: Two observers registered PET and CT data obtained in 37 patients using a commercially available image fusion tool. RIR was performed separately for the thorax and the abdomen using physiological FDG uptake in several organs as a reference. One observer performed the procedure twice (O1a and O1b), another person once (O2). For 94 malignant lesions, clearly visible in CT and PET, the signed and absolute distances between their representation on PET and CT were measured in X-, Y-, and Z-direction with reference to a coordinate system centered in the CT representation of each lesion (X-, Y-, Z-distances). RESULTS: The mean differences of the signed and absolute distances between O1a, O1b, and O2 did not exceed 3 mm in any dimension. The absolute X-, Y-, and Z-distances ranged between 0.57 +/- 0.58 cm for O1a (X-direction) and 1.12 +/- 1.28 cm for O2 (Z-direction). When averaging the absolute distances measured by O1a, O1b, and O2, the percentage of lesions misregistered by less than 1.5 cm was 91% for the X-, 88% for the Y-, and 77% for the Z-direction. The larger error of fusion determined for the remaining lesions was caused by non-rigid body transformations due to differences in breathing, arm position, or bowel movements between the two examinations. Mixed effects analysis of the signed and absolute X-, Y-, and Z-distances disclosed a significantly greater misalignment in the thorax than in the abdomen as well as axially than transaxially. CONCLUSION: The anatomical inaccuracy of RIR can be expected to be <1.5 cm for the majority of neoplastic foci. Errors of alignment are bigger in the thorax and in Z-direction, due to non-rigid body transformations caused, e.g., by breathing.

Fluorodeoxyglucose F18↗
PubMed2004

Dose reduction in subsecond multislice spiral CT examination of children by online tube current modulation.

The potential of online tube current modulation in subsecond multislice spiral CT (MSCT) examinations of children to reduce the dose without a loss in image quality is investigated in a controlled patient study. The dose can be reduced for oval patient sectional view without an increase in noise if the tube current is reduced where the patient diameter and, consequently, attenuation are small. We investigated a product version of an online control for tube current in a SOMATOM Sensation 4 (Siemens, Forchheim). We evaluated image quality, noise and dose reduction for examinations with online tube current modulation in 30 MSCT of thorax/abdomen and abdomen and compared mA s for tube current modulation to the mA s in standard weight-adapted children protocols. Image quality was rated as "very good," "good," "diagnostic" and "poor" in a consensus by three radiologists. Noise was assessed in comparison to 24 MSCT examinations without tube current modulation measured as SD in ROIs. The dose was reduced from 26 to 43% (mean 36%), depending on the patient's geometry and weight. In general, no loss of image quality was observed. Measured noise showed a decrease up to 26% and an increase up to 36%, although there was no decrease of image quality. Online tube current modulation is now used as a standard in MSCT at our institution. Dose in MSCT examinations of children can be reduced substantially in routine examinations by online tube current modulation without a loss of image quality.

Child↗
PubMed2004

[CTA of carotid artery with different scanner types].

Noninvasive modalities like CTA are increasingly replacing selective angiography in the evaluation of carotid artery stenosis. Dedicated scan protocols and contrast injection techniques are mandatory for the morphological assessment of carotid artery stenosis. These protocols need to be adapted to different scanner types. The delineation of plaque components and the residual lumen is improved with high resolution scan protocols and dedicated reconstruction algorithms. The exact delineation of in-stent stenosis remains limited. Standardization of postprocessing is crucial in order to attain reproducible results. Multislice spiral CT allows reliable grading of carotid artery stenosis. Relevant venous opacification and pulsation artifacts have to be expected with 4-slice scanners, the short scan time of the latest CT scanners minimize these problems.

Carotid Artery, Internal↗
PubMed2004

[3D ultrasound in core breast biopsy].

AIM: To evaluate the potential of three-dimensional ultrasound (3D US) in core biopsy of suspicious breast lesions. METHOD: 3D US controlled core biopsy was performed in 107 breast masses in 100 women by using an automated biopsy system (11G coaxial needle, 12 G biopsy needle). Mean diameter of the lesions was 1.55 cm (0.5 - 3.5 cm). A linear 3D US volume scanner was used for the procedure. Localization of the lesion and placement of the needle were initially done under 2D US guidance. After core needle stroke a 3D US volume acquisition was performed to correlate lesion and needle position. In the case of eccentric needle position the needle was repositioned under 3D control. 5 specimens were taken from each lesion. The histological results from the specimens were correlated with the results from surgery or clinical follow-up (> 2.5 years). RESULTS: Biopsy was taken from 59 probably benign (BI-RADS 3 - 4) and 48 malignant (BI-RADS 5) lesions. 3D US revealed 61 central, 44 eccentric and 2 marginal needle positions after the initial 2D guidance. Central repositioning of the needle was achievable under 3D guidance in all patients. Histological examination of the specimens revealed 41 invasive carcinomas and one in-situ carcinoma (DCIS). In one lesion, the carcinoma was missed in the core biopsy, despite central hits of the biopsy needle. This led to a sensitivity of 98 %, specificity of 100 %, PPV of 100 %, NPV of 98.5 % and accuracy of 99 % for the diagnosis of a malignant lesion. CONCLUSION: 3D US improves needle positioning as well as the depiction of correct needle placement in freehand core biopsy.

Adult↗
PubMed2004

[Automatic exposure control to reduce the dose in subsecond multislice spiral CT: phantom measurements and clinical results].

PURPOSE: To investigate the potential of dose reduction in multislice spiral CT (MSCT) with automatic exposure control. MATERIALS AND METHODS: The study was performed on a Sensation 4 multislice scanner. This prototype implementation analyzed the distribution of the attenuation along the z-axis in the lateral and sagittal directions of the digital radiogram. Depending on this distribution of the attenuation, the tube current (mA) is defined for every tube rotation. In addition, the tube current was modulated during each tube rotation. First, a three step oval water phantom was measured to evaluate the potential of this method with respect to dose reduction and image quality. In a patient study (n = 26), four different scan regions (shoulder, thorax, abdomen, pelvis) were examined and dose (mAs) and image quality evaluated in comparison to examinations with a standard protocol for these regions in adults and a weight-adjusted standard protocol in children. The image quality was classified in consensus as good, sufficient and poor image quality. RESULTS: By adapting and modulating the tube current, we substantially reduced the variation of noise in one spiral scan and in one scan region of our patient collective. The dose (average mAs) was reduced by 31 % to 66 % in children (mean 44 %) and between 35 % and 64 % in adults (mean 53 %), depending on the scan region. The image quality was substantially improved in regions with high attenuation and did not suffer in low attenuation regions. CONCLUSION: The dose can be reduced substantially by an automatic exposure control including angular tube current modulation with the same or improved image quality.

Abdomen↗
PubMed2004

[Phantom study for the detection of simulated lesions in five different digital and one conventional mammography system].

PURPOSE: Experimental phantom study for the detection of simulated lesions with five different digital and one conventional screen-film mammography system. MATERIALS AND METHODS: Three radiographs were obtained at various configurations of the phantom with one conventional screen-film system (Mammomat 3000 N) (Siemens), five digital systems (high resolution computed radiography system [Fuji/Siemens], one a-Si detector [GE Medical Systems], two a-Se detectors [Siemens; Hologic / Lorad] and one CCD detector [Fischer Imaging]), applying the same exposure parameters. The Wisconsin Mammographic Random Phantom, Model 152 A, was used. Five investigators with different experience in mammography (3 months to more than 4 years) evaluated the 18 randomly selected radiographs. RESULTS: No significant differences were found in the detection rate of simulated breast lesions for conventional screen-film mammography (84.9 %), high resolution computed radiography (86.7 %) and digital mammography with an a-Si detector (89.8 %). Highly significantly better results (p < 0.001) were found with the two a-Se systems (97.3 %) and the CCD system (100 %). CONCLUSION: Conventional screen-film mammography can be replaced by high resolution computed radiography and digital mammography with a-Si-, a-Se- and CCD-detectors. This has to be confirmed in further clinical studies.

Computer Simulation↗
PubMed2003

[Sonographical breast biopsy: how many core biopsy specimens are needed?].

PURPOSE: To determine the optimum number of specimens of a sonographically guided core biopsy of the breast. MATERIALS AND METHODS: From January 2001 to April 2001, sonographically guided core biopsies (coaxial needle: 11 G; core needle: 12 G) were performed on 106 patients with 115 BI-RADS trade mark 4-5 lesions that had corresponding sonographic findings. Five specimens were obtained in anteroposterior direction parallel to the chest wall and each specimen examined histologically. RESULTS: A total of 575 core biopsies produced 545 specimens (94.8 %), with no material obtained in 30 biopsies (5.2 %). The first and second specimen confirmed the diagnosis in 99 of 115 lesions (86 %), with subsequent specimens confirming the diagnosis in 87 % (3 rd specimen), 88 % (4 th specimen) and 82 % (5 th specimen). The additive accuracy of the five core breast specimens was 86 %, 96 %, 98 %, 99 % and 100 %. The possible volume of 78.9 mm 3 as determined by the sample notch of the core needle only furnished an average volume of 38.1 mm 3 (41.1 mm 3 for the 1 st, 40.1 mm 3 for the 2 nd, 37.5 mm 3 for the 3 rd, 36.7 mm 3 for the 4 th and 35.0 mm 3 for 5 th core specimen). CONCLUSION: Sonographically guided core breast biopsy (coaxial needle: 11 G; core needle: 12 G) may require five passes to achieve a diagnostic accuracy of more than 99 %.

Adult↗