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Biomedical subjects

M F Reiser

Publications and source records attributed to M F Reiser.

At least 127 records · Page 7Linked to original sources
PubMed1998

Hybrid rendering and virtual endoscopy of the auditory and vestibular system.

A hybrid rendering method (color-coded 3D shaded-surface and volume display) with the possibility of virtual endoscopy using image data sets from HR-SCT was developed. To show the possible advantages and benefits of the improved rendering algorithm we have specifically highlighted the use in relation to the auditory and vestibular system. Postprocessing image visualization offers improved morphological analysis, and will benefit radiological diagnostics, medical education, surgical planning, surgical training and postoperative assessment.

Adult↗
PubMed1998

[Radiation exposure during CT examination of thorax and abdomen. Comparison of sequential, spiral and electron beam computed tomography].

Comparison of radiation exposure applied by different types of CT scanners for the investigation of the chest and abdomen. Determination of radiation exposure applied by multi-phase spiral CT. Estimation of the dose in air in the system axis of the scanner, the CT dose index (CTDI) and the effective dose for electron beam tomography (EBT) and two conventional CT scanners (sequence, SEQ; spiral, SCT). For EBT, dose in system axis for investigation of the abdomen was above 50 mGy. Effective dose for investigation of the chest and abdomen was higher with EBT (11 and 26 mSv, respectively) than with conventional CT (SEQ, 4 and 20 mSv; SCT, 2 and 7 mSv). The effective dose for a biphasic investigation (liver 5 mSv, kidney 4 mSv) was below, for a triphasic investigation (liver 7 mSv) above the effective dose of the investigation of the abdomen (6 mSv). Investigation of the abdomen with the EBT should only be performed for certain indications. With spiral CT, effective dose is much lower than with EBT.

Abdomen↗
PubMed1998

[Virtual and three-dimensional bronchoscopy with spiral and electron beam computed tomography].

PURPOSE: To compare spiral computed tomography (CT) and electron-beam CT (EBT) for 3D and virtual CT-bronchoscopy. MATERIALS AND METHODS: 17 patients with various disorders of the tracheobronchial system were examined using fiberoptic bronchoscopy, spiral CT and EBT. 3D images were reconstructed from CT data sets using automated segmentation based on volume-growing methods. Surface-rendered, volume-rendered, and hybrid reconstructions were visualized in real time using a data helmet. RESULTS: All data sets could be processed to high-quality three-dimensional (3D) and virtual reconstructions. The reduction of motion artifacts due to shorter scan times made EBT data sets better suited for automated segmentation and less susceptible to motion artifacts. 3D and virtual reconstructions did not increase the diagnostic sensitivity of CT compared to axial reconstructions alone. CONCLUSIONS: Shorter scan times of CT imaging yield higher-quality 3D and virtual reconstructions. Modern reconstruction techniques are valuable visualization tools for select indications and are the prerequisite for future developments in computer-aided medicine.

Bronchial Neoplasms↗
PubMed1998

[Virtual colonoscopy using CT and MRI].

PURPOSE: To evaluate experimentally and in patients the sensitivity and effective dose of virtual electron-beam tomography (EBT) colonoscopy for detecting small colon tumors and to compare the methods and results with virtual colonoscopy using spiral CT and MR imaging in a review of the literature. MATERIALS AND METHODS: Six polyps with diameters between 3 and 12 mm were created and randomly placed in resected pig colon. After distension with air, the pig colon was scanned with continuous volume scanning (CVS, 3 mm collimation) and a pitch of 0.4, 0.8 and 1.5. Twenty patients positive for the fecal blood test were examined after rectal CO2 insufflation and i.v. administration of 1 mg glucagon. A 13 s CVS scan was used to cover the entire colon within one breath-hold. 3D volume-rendered fly-throughs were evaluated by two independent radiologists. Effective dose equivalent was estimated using an Alderson phantom equipped with thermoluminescence dosimeters. RESULTS: In the tumor model, all polyps were detectable at a pitch of 1.5. A further reduction of the pitch ratio did not improve the conspicuity of the polyps. In patient studies, all tumors (n = 4) and polyps (n = 3) were correctly identified on 3D fly-throughs. Two false positive results were obtained. Effective dose equivalent was calculated at 3.2 mSv per scan. CONCLUSIONS: Our preliminary results indicate that virtual EBT colonoscopy holds promise for fast screening for colon polyps. The best technique for virtual colonoscopy (Spiral CT, EBT, MRI) has not yet been determined and the future role of virtual colonoscopy must still be defined.

Colonic Polyps↗
PubMed1998

[Technical bases and acquisition conditions of electron-beam computed tomography].

PURPOSE: In this review the technical principle and scanner characteristics of electron beam computer tomography (EBCT) are discussed. METHODS: In contrast to conventional CT, image acquisition in EBCT is achieved without mechanically moving parts. This construction allows for short acquisition times in investigating given anatomical regions (100 ms per slice) or up to 8 levels without table movement and short interscan delays (50 ms per slice). RESULTS: Depending on the nature of the investigation, the scanner can be used in the single slice, continuous volume scanning and multi slice mode. The single slice mode is used for detection and quantification of coronary calcifications and for CT angiography of the coronary vessels. Equivalent to the spiral mode in conventional CT, continuous volume scanning may be used for routine investigation of the chest and abdomen. Functional investigations of the heart and perfusion measurement of different organs can be performed in multi slice mode. Because of the geometry of the electron beam scanner, radiation exposure for certain investigations is above the exposure with conventional CT. CONCLUSION: Future developments will focus on dose efficient radiation collimation, high resolution detector systems and artefact reducing reconstruction kernels.

Algorithms↗
PubMed1998

[Methods of quantification of coronary artery calcifications with electron-beam and conventional computed tomography].

PURPOSE: To compare electron beam CT (EBCT) und prospectively ECG gated conventional CT for the detection and quantification of coronary artery calcifications. METHODS: 42 patients (mean age 62.8 +/- 8.8 years) were scanned, both with EBCT and ECG gated sequential CT. For quantification, the traditional "total calcium score" (TCS) according to the Agatson method as well as the "volumetric calcium score" (VCS) as determined with a stand-alone workstation (NetraMD) was calculated for both modalities. RESULTS: There was close correlation between EBCT and conventional CT, both for TCS (r = 0.984) as well as for VCS (r = 0.986) score values. The median difference was 17% for TCS and 13% for VCS. The difference between the two modalities was not statistically significant (p = 0.44). CONCLUSION: EBCT and prospectively ECG triggered conventional CT are equivalent for the quantification of coronary artery calcifications. The extent of calcifications can be established with both modalities using either TCS or VCS score values.

Age Factors↗
PubMed1998

[Diagnosis of pulmonary embolism with spiral and electron-beam CT].

PURPOSE: To compare spiral (SCT) and electron-beam CT (EBT) for the diagnosis of pulmonary embolism (PE). MATERIALS AND METHODS: From June 1997 to June 1998 188 patients with suspected acute or chronic thromboembolism of the pulmonary arteries were examined. A total of 108 patients were scanned using SCT and 80 patients using EBT. On each scanner two different scan protocols were evaluated. RESULTS: PE was diagnosed in 38 patients using EBT and in 49 patients using SCT. Especially with EBT, isolated peripheral emboli could be confidently diagnosed. When EBT and SCT were compared for the analysis of peripheral pulmonary arteries, some paracardiac segmental and subsegmental vessels were significantly better analyzable with EB. Additional or diseases other than PE were diagnosed in 112 patients. Other diagnoses included bronchial carcinoma and aortic dissection. CONCLUSIONS: Advanced CT scanning techniques allow the highly accurate diagnosis of central and peripheral PE. Other potentially life-threatening underlying diseases are also readily recognized.

Aortic Dissection↗
PubMed1998

[Comparison of a high-end ultrasound system with a spiral CT scanner in screening for liver metastases].

AIM: To assess prospectively the sensitivity of a high-end ultrasound system in comparison to a spiral computed tomographic scanner in screening for liver metastases. METHOD: 88 consecutive patients with malignant diseases were examined using gray-scale sonography and contrast enhanced two-phase spiral computed tomography during arterial dominant and portal venous phase. For both methods all focal lesions of the liver were reported. RESULTS: 99 focal lesions of the liver were detected by gray-scale sonography and/or two-phase spiral computed tomography. The sensitivity for gray-scale sonography was 93.9% (93 of 99 lesions) and for two-phase spiral computed tomography (71.7% (71 of 99 lesions), respectively. CONCLUSION: Screening for liver metastases should be performed by using a diagnostic method with a high sensitivity. Gray-scale sonography with a high-end ultrasound system fulfill' these requirements.

Adult↗
PubMed1998

Parametrial invasion in cervical carcinoma: evaluation of detection at MR imaging with fat suppression.

PURPOSE: To evaluate detection of parametrial invasion at magnetic resonance (MR) imaging with fat suppression. MATERIALS AND METHODS: In 35 patients with cancer of the cervix, MR imaging was performed with the following sequences: T2-weighted turbo spin echo (SE), turbo short inversion time inversion recovery (STIR), and unenhanced or gadolinium-enhanced T1-weighted SE with and without excitation-spoiling fat suppression. Images obtained with each sequence were evaluated for parametrial invasion by two blinded radiologists separately, who scored their level of diagnostic confidence from 0 to 10 (no confidence to high confidence). Then, all images were evaluated together and findings were correlated with histopathologic findings. RESULTS: No statistically significant differences were found between staging with T2-weighted turbo SE, turbo STIR, and T1-weighted fat-suppressed gadolinium-enhanced SE images. Staging with T1-weighted SE, T1-weighted gadolinium-enhanced SE, and T1-weighted fat-suppressed SE images was significantly worse (P < .05). Diagnostic confidence was lower (P < .001) with T1-weighted gadolinium-enhanced SE and T1-weighted fat-suppressed gadolinium-enhanced SE images (5.5 and 6.2 points, respectively) compared to staging with T2-weighted turbo SE and turbo STIR images (8.2 and 7.6 points, respectively). No statistically significant improvement in staging accuracy was found when all images were evaluated together. CONCLUSION: In MR diagnosis of parametrial invasion, the addition of fat-suppressed or gadolinium-enhanced MR images did not improve the accuracy with T2-weighted turbo SE images alone.

Cervix Uteri↗
PubMed1998

Patency of coronary bypass grafts: assessment with breath-hold contrast-enhanced MR angiography--value of a non-electrocardiographically triggered technique.

PURPOSE: To determine the value of non-electrocardiographically triggered contrast material-enhanced magnetic resonance (MR) angiography in assessing the patency of venous and internal thoracic artery (ITA) grafts after coronary bypass surgery. MATERIALS AND METHODS: Twenty-seven patients with 76 coronary bypass grafts (48 venous, 28 ITA) were examined 26.5 months +/- 5.8 after surgery with MR angiography and conventional angiography. MR angiography was performed with a three-dimensional gradient-echo sequence after automated injection of contrast material; contrast agent administration was based on measurement of the individual transit time of the agent. Results of MR angiography were interpreted by two independent observers and compared with results of conventional angiography. RESULTS: The independent interpretations of the MR angiograms agreed with the results of conventional angiography in 96% and 91% of the grafts. After a final consensus reading, sensitivity was 95% for all grafts, 94% for venous grafts, and 96% for ITA grafts. Specificity was 85% for venous grafts and 67% for ITA grafts. Positive predictive value was 95% for all grafts, 94% for venous grafts, and 96% for ITA grafts. CONCLUSION: Non-electrocardiographically triggered contrast-enhanced MR angiography allows reliable assessment of the patency of venous and arterial coronary bypass grafts.

Adult↗
PubMed1997

Magnetic resonance imaging of the female pelvis. New circularly polarized body array coil versus standard body coil.

RATIONALE AND OBJECTIVES: The authors compare the value of a new circularly polarized body array coil (BAC) system with a standard body coil (BC) for high-resolution magnetic resonance imaging of the female pelvis. METHODS: Twenty patients with cervical cancer were examined with a BC and BAC. Imaging parameters were kept constant (sagittal T2-weighted turbo spin-echo: repetition time = 4000 mseconds; effective echo time = 99 mseconds; 160 x 160 mm field of view; 256 x 256 matrix; 0.63 x 0.63 mm pixel size; 4-mm slice thickness). Images were scored for lesion-to-organ delineation and overall image quality/ artifacts using a scale from 5 to 1 (excellent to poor). Signal-to-noise (S/N) ratios for different tissues (tumor, uterus, vagina, rectum, muscle, and fat) as well as contrast-to-noise (C/N) ratios between tumor and (1) uterus, (2) vagina, and (3) rectum were calculated. Magnetic resonance tumor staging was performed according to the International Federation of Gynecology and Obstetrics (FIGO) classification. RESULTS: Using the BAC, S/N and C/N ratios increased significantly compared with the BC (S/N: 2.7-3.4-fold increase for all organs evaluated, P < 0.001: C/N: tumor versus uterus 2.4-fold, P < 0.01; tumor versus vagina 6.1-fold, P < 0.001; tumor versus rectum 3.1-fold, P < 0.01). This resulted in an improved overall image quality (average ratings: BAC-4.3 points; BC-2.6 points; P < 0.001). Lesion-to-organ delineation (average ratings: BAC 4.3-4.1 points, BC 3.5-2.7 points for all organs evaluated; P < 0.001) was increased noticeably on BAC images. No significant difference was found for staging accuracy. CONCLUSIONS: Circularly polarized BAC provide superior S/N and C/N ratios and improve lesion conspicuity compared with standard BC.

Adult↗
PubMed1997

The art and science of dream interpretation: Isakower revisited.

Dream imagery presents a special opportunity to lead patient and analyst through the patient's network of memories to the discovery of unconscious memories that have complicated and interfered with the patient's attempts to resolve important life problems. This is an important, perhaps indispensable, first step on the way to successful working through to solutions that are more rational and realistic than the neurotic symptoms that brought the patient to treatment in the first place. Theoretical and empirical rationales are presented for a technical approach to dreams that takes full advantage of the special opportunities that working with dream imagery provides: for deepening the psychoanalytic process and for acquainting the patient with principles of mental function applicable to aspects and phases of the analytic process that he/she will encounter as the work progresses.

Adult↗
PubMed1997

MR imaging of enhancing intraosseous disk herniation (Schmorl's nodes).

OBJECTIVE: This study was conducted to show vascularization of Schmorl's nodes with enhanced MR imaging and to correlate this finding with clinical complaints. MATERIALS AND METHODS: Retrospectively, 412 gadopentetate dimeglumine-enhanced MR imaging examinations of the lumbar and thoracic spine of 372 patients were reviewed for Schmorl's nodes, vascularization of Schmorl's nodes, and associated bone marrow edema. Sagittal T2-weighted spin-echo and unenhanced and enhanced T1-weighted spin-echo images with and without fat suppression were evaluated in symptomatic and asymptomatic patients. RESULTS: Of the 372 patients, 142 (38%) had 341 Schmorl's nodes. Gadopentetate dimeglumine-enhanced MR imaging revealed vascularized tissue in 30 Schmorl's nodes of 23 patients (mean age of patients, 53 years old). Associated bone marrow edema was found in nine of 30 vascularized Schmorl's nodes. The mean diameter (8.2 mm) of the nine vascularized Schmorl's nodes that were surrounded by bone marrow edema was significantly (p < .05) greater than the mean diameter (6.4 mm) of the 21 vascularized Schmorl's nodes that had no bone marrow edema. The vascularized Schmorl's nodes were significantly (p < .05) smaller in the seven asymptomatic patients (mean, 5.2 mm) than in the 23 patients with back pain (mean, 7.9 mm). We saw bone marrow edema adjacent to Schmorl's nodes less frequently in asymptomatic patients (one of seven) than in symptomatic patients (10 of 23). CONCLUSION: Vascularized Schmorl's nodes were larger and more frequently associated with bone marrow edema in patients with back pain than in asymptomatic patients. Enhanced MR images of Schmorl's nodes revealed vascularity, which was not shown on unenhanced MR images.

Adult↗
PubMed1996

Identification of characteristics for malignancy of solitary pulmonary nodules using high-resolution computed tomography.

The aim of this prospective study was to apply the described single pathological appearance and possibilities of differentiating signs from other studies and summarize them concerning their differential diagnostic importance to improve differential diagnostic strategies concerning the dignity of solitary pulmonary nodules. 55 consecutive patients with solitary pulmonary nodules were examinated using high-resolution computed tomography (HRCT) before surgery. Thereafter HRCT-diagnosis was proven by histological assessment. Only lesions which were removed by surgery were used. No lesion was excluded by size. Necrotic areas, cavitation, satellite lesions and circumscribed pleural thickening were only found in the malignant nodules. Discrimination between benign and malignant lesions was possible by: mean diameter (P<.01), mean density (P<.01) and air inclusion (P<.05), by air bronchogram/bronchiologram (P<.05), indistinct/fogged (P<.05) and dystelectatic (P<.01) margin, the presence (P<.01) and length (P<.01) of spiculae, spiculae extended into the pleura visceralis (P<.05) and pleural distension (P<.01). A single sign can be seen in either benign or malignant nodules, but if considered together with other signs it may have a different meaning. HRCT can enable a differentiation of BSPN from MSPN in the majority of cases. As imaging methods could not get a nearly complete certainty about the dignity the chance of survival of patients could be preserved exclusively by an early surgery.

Carcinoma↗
PubMed1996

[Comparison between current and high resolution ultrasound for diagnosis of breast lesions].

AIM: To assess the value of high-resolution ultrasound in the diagnosis of breast lesions. METHOD: Fifty women with a clinically suspicious breast mass were examined with mammography, conventional and high-resolution sonography. Ultrasound was performed with a linear-array 7.5-mHz transducer and an annular-array 13.0 MHz transducer. RESULTS: Histology showed carcinoma in 28 patients, fibrocystic changes in 20 and fibroadenoma in 2. High-resolution ultrasound characterized 18 lesions more accurately than conventional ultrasound, including 13 carcinomas, 3 fibrocystic changes and 2 fibroadenomas. The size of 8 carcinomas was measured more accurately with high-resolution ultrasound than with conventional ultrasound. CONCLUSION: High-resolution ultrasound is more valuable in the differentiation and size determination of breast lesions than conventional ultrasound.

Adolescent↗