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Biomedical subjects

M F Reiser

Publications and source records attributed to M F Reiser.

At least 109 records · Page 6Linked to original sources
PubMed1999

T2-weighted breathold imaging of the liver: a quantitative and qualitative comparison of fast spin echo and half Fourier single shot fast spin echo imaging.

The imaging characteristics of two EPI-hybrid breath-hold sequences, T2-weighted fast spin-echo [FSE, effective echo time (TEeff) 138 ms] and half Fourier single shot turbo spin-echo (HASTE, TEeff 60 ms), were compared in hepatic imaging. A total of 111 patients with suspected hepatic disease were studied at 1.5 Tesla using a body phase-array coil. The signal-to-noise (S/N) and contrast-to-noise (C/N) ratios for organs and lesions were calculated and quantitatively compared. Organ delineation, visualization of anatomical structures and pathological lesions, artifacts, and total image quality were qualitatively assessed and statistically compared. The final diagnoses were metastases from colorectal, breast, and pancreatic cancer in 23/111, hepatocellular carcinoma in 15/111, cysts in 19/111, hemangiomas in 9/111, several other lesions in 7/111, and no lesions in 38/111 of the cases. A total of 139 lesion in 73% of the patients were seen while 85% of the lesions were at least 1.5 cm in size. Regarding S/Ns HASTE was significantly (P < 0.03) superior to FSE with only minor (P > 0.05) differences in C/Ns between the two sequences for anatomical and pathological structures. HASTE demonstrated in almost all (97.3%) of the cases no artifacts, while on fast SE imaging moderate to minor artifacts were present in 23.5-51.7% of the cases. The overall image quality and diagnostic confidence was rated significantly higher (good 43.2%, excellent 53.2%) for HASTE than for fast SE imaging (good 44.8%, excellent 17.6%). Providing comparable C/Ns for anatomical and pathological structures, breatheld HASTE imaging proved to be superior to fast SE in T2-weighted imaging of the upper abdomen regarding general image quality, and, with adequate technical prerequisites, may be a suitable substitute of fast T2-imaging techniques.

Evaluation Studies as Topic↗
PubMed1999

[Computed tomography of the abdomen with multidetector-array CT].

BACKGROUND: The advent of multidetector CT (MDCT) constitutes a quantum leap creating a wealth of new opportunities in medical imaging. However, while the basic principles of spiral CT still apply, we are now challenged to rethink our strategies in planning a CT study to take full advantage of the increased capabilities of MDCT. MATERIALS AND METHODS: We report here our preliminary experiences with MDCT for abdominal CT imaging within a 5-month period. During this time, suitable protocols for investigation of the abdomen using MDCT were developed. The capabilities of MDCT allow for tailoring dedicated CT protocols for routine applications as well as for biphasic liver studies and CT angiography of the aorta and abdominal vessels. RESULTS: The speed of MDCT can either be used to reduce the time needed to cover a given volume, or to use narrower beam collimations to increase the resolution of detail along the z-axis and reduce volume averaging. Higher scan speed allows reduction of the amount of contrast material in vascular applications and suppression of motion artifacts. Higher spatial resolution with thinner collimations reduces volume averaging and improves the detection of small hepatic and pancreatic lesions. Detailed analysis of vascular structures and high-quality three-dimensional reformations become feasible. New problems arise from the large amount of data generated by MDCT. CONCLUSIONS: MDCT offers a wealth of new opportunities that help us to come to a fast and accurate diagnosis in suspected abdominal disease. Traditional indications for performing CT are reemphasized and new clinical applications can be exploited.

Abdomen↗
PubMed1999

[Comparison of dual-phase helical CT with native and ferum oxide-enhanced magnetic resonance imaging in detection and characterization of focal liver lesions].

PURPOSE: Evaluation of the diagnostic efficacy of contrast-enhanced, dual-phase spiral CT and MRI before and after administration of SPIO particles in focal hepatic disease with previously uncertain diagnosis. MATERIAL AND METHODS: In 46 patients in whom primary or secondary hepatic malignancy was suspected, dual-phase spiral CECT and breath-held T1-weighted gradient-echo and T2-weighted fast spin-echo MRI (1.5 T, body-phased-array coil) before and after SPIO administration were compared. The indications for the subsequent MRI studies were based on ambiguous findings on CECT. The number of hepatic lesions, the overall lesion detection and characterization was evaluated by consensus and compared to the gold standard (histological proof in 30/46 of the cases, long-term follow-up in 16/46 of the cases). RESULTS: In 34 of 46 cases the correct diagnoses were established by CECT (sensitivity 96%, specificity 48%) revealing significantly less lesions than MRI. Unenhanced MRI had sensitivity of 93% and specificity of 71%, whereas SPIO-enhanced MRI had sensitivity of 97% and specificity of 88%. The differences between the modalities were even more pronounced in the detection of lesions smaller than 10 mm with SPIO-MRI as the most sensitive method. CONCLUSIONS: In this problem-oriented scenario, SPIO-enhanced MRI was superior to spiral CT and unenhanced MRI regarding the diagnostic efficacy in the pre-operative work-up of focal liver lesions. SPIO-enhanced MRI can be recommended as a problem-solving tool for the clinical routine.

Adult↗
PubMed1999

[The technical bases and uses of multi-slice CT].

In this review the technical principles and applications of multi-slice CT are discussed. Multi-slice CT systems allow simultaneous acquisition of up to 4 slices by using multi-row detector systems. Intuitive geometrical arguments are used to establish the limitation to a maximum of 4 slices which is kept by all currently existing multi-slice CT systems. Two different construction principles of the detector are discussed, the "Fixed Array" detector and the "Adaptive Array" detector. The extension of conventional 360 LI and 180 LI spiral interpolation techniques to multi-slice spiral CT is explained as well as a new generalized multi-slice spiral weighting concept, the so-called "Adaptive Axial Interpolation". Several techniques to improve multi-slice spiral image quality are discussed. Finally, some examples for clinical applications are given, and the principle of ECG triggered and ECG gated cardiac examinations with optimized temporal resolution is presented. Multi-slice CT systems are a milestone with respect to increased volume coverage, shorter scan times, improved axial (longitudinal) resolution and better use of the X-ray tube output. Additionally, new clinical applications are possible such as Cardiac CT.

Electrocardiography↗
PubMed1999

[Imaging of the thorax with multislice spiral CT].

With multislice spiral computed tomography (MSCT), existing indications for performing CT of the chest are strengthened and new applications are emerging. The high speed of MSCT improves efficiency, image quality and patient comfort of "routine" imaging of the chest. The ability to cover large volumes with thin slices improves the evaluation of mediastinal lymph nodes and pulmonary nodules and allows for high-quality secondary reconstruction. If a comprehensive diagnosis of the mediastinal structures and the pulmonary parenchyma is desired, MSCT for the first time allows reconstruction of contiguous and high-resolution (HRCT) sections from the same set of thin-collimation raw data. This way, contiguous chest images of superior and HRCT sections of equal image quality compared to conventional CT scanning can be obtained. Vascular protocols greatly benefit from the high speed of MSCT: For imaging the thoracic aorta or pulmonary emboli (PE), the amount of contrast material can be substantially reduced. Owing to thin collimation, the detection rate of small peripheral emboli can be significantly increased. If indicated, the entire subphrenic venous system can be evaluated during the same session, without additional contrast material.

Adult↗
PubMed1999

[Image analysis in multislice spiral CT of the lung with MPR and MIP reconstructions].

PURPOSE: To test, whether axial, coronal and sagittal MIP and MPR reconstructions of diagnostic quality can be obtained from 1-mm collimation MSCT data of the chest for the evaluation of thoracic anatomy and pathology. MATERIALS AND METHODS: 1-mm collimation MSCT scans were obtained with a pitch of 6 in an acrylic phantom and in 20 patients. Axial images were reconstructed with 0.6-mm increment. Multiplanar reformations (MPRs) and sliding thin-slab maximum intensity projections (STS-MIPs) were reconstructed in axial, coronal and sagittal planes. Images were printed in lung windows and evaluated by three readers by using a standardized evaluation scheme. RESULTS: Overall, both methods allowed good visualization of anatomic structures. MIP was superior for visualization of the pulmonary arteries (p < 0.05) while central and peripheral bronchi and the lung parenchyma were better depicted on multiplanar reconstructions. A confident diagnosis of thoracic pathology was feasible using both modalities, however MIPs appeared less usefull for evaluation of gross parenchymal abnormalities, such as pneumonic infiltrates or fibrotic changes. No significant difference in the degree of motion artifacts were detected between both modalities. CONCLUSION: MSCT data sets are ideally suited for generating MPR and MIP reconstructions. While MIPs are superior for the evaluation of thoracic vessels, MPR is advantageous for visualizing central and peripheral bronchi and the pulmonary parenchyma.

Humans↗
PubMed1999

[Partial priapism. Case report and review of the literature of diagnostic and therapeutic measures].

Partial priapism is a rare condition which has been previously reported in the literature only in eight cases. Unlike the typical case of priapism, patial priapism generally shows erection only of the proximal corpora cavernosa. In most of the cases a well defined membrane separated the proximal erected and the distal flaccid part of the corpus. The origin of the fibrous membrane is not clear. Usually a painful segmental thrombosis of the corpora cavernosa was found proximal the membrane. Until 1985 diagnosis and therapy of this entity have principially involved invasiv methods. Later computed tomography (CT) and magnetic resonance (MR) were used for noninvasive imaging and conservative management was elected. We report a case of partial priapism and review the diagnostic and therapeutic procedure in the previous literature.

Adult↗
PubMed1999

Evaluation of the carotid and vertebral arteries: comparison of 3D SCTA and IA-DSA-work in progress.

OBJECTIVE: The purpose of this study was to develop a method for three-dimensional (3D) visualization of the whole vascular system of the carotid and vertebral arteries using spiral computed tomographic angiography (SCTA), that allows accurate, qualitative and quantitative evaluation, of anatomical abnormalities, including detection of additional lesions, and estimation of degree of stenosis. MATERIALS AND METHODS: Fifteen patients with anatomical and pathological abnormalities of the arterial vascular system detected by color-coded duplex ultrasound were studied using intraarterial digital subtraction angiography (IA-DSA) with aortic arch injection, and SCTA. The carotid and vertebral arteries were segmented using an interactive threshold interval density volume-growing method and visualized with a color-coded shaded-surface display (SSD) rendering method. The adjacent bone structures were visualized using a transparent volume rendering method. RESULTS: In all cases, the entire volume of the vascular system of the carotid and vertebral arteries could be visualized on SCTA, and the anatomical and pathological abnormalities on 3D SCTA correlated well with that seen on IA-DSA. CONCLUSION: Results of 3D SCTA had a high degree of correlation with results of IA-DSA in the evaluation of the vascular system of the carotid and vertebral arteries. The 3D SCTA with a subsecond spiral CT scanner is useful for the visualization of anatomical and pathological abnormalities in the circulation in the carotid and vertebral arteries and offer a promising minimally invasive alternative compared with other diagnostic procedures.

Adult↗
PubMed1999

Usefulness of morphological characteristics for the differentiation of benign from malignant solitary pulmonary lesions using HRCT.

The aim of this study was to analyze different characteristics on high-resolution computed tomography (HRCT) that help differentiate benign solitary pulmonary lesions (BSPLs) from malignant solitary pulmonary lesions (MSPLs). High-resolution computed tomography was performed on 104 consecutive patients with SPLs. The whole lesion was examined with a slice thickness of 1 mm and a 12-cm field of view. All lesions were surgically excised within 24 h of the CT examination. Satellite nodules, cavitations, and necrosis were found only in MSPLs. Useful characteristics for the differentiation of BSPLs from MSPLs were the presence of spicules (p < 0.00005), spicules extending to the visceral pleura (p < 0.0005), the vessel sign (p < 0.0005), pleural retraction (p < 0.001), circumscribed pleural thickening (p < 0.001), the bronchus sign (p < 0.005), the presence of ground-glass attenuation adjacent to the SPL (p < 0.01), the density of the lesion (p < 0.05), and the length of spicules (p < 0.05). Using the significant characteristics p < 0.01 for the identification of MSPLs, a sensitivity of 91.4 % and a specificity of 56.5 % (accuracy of 83.7 %) was found. A precise morphological assessment of the periphery of the pulmonary lesion is necessary. The HRCT technique is useful in differentiation of BSPLs from MSPLs. However, metastases strongly resembled benign lesions in terms of size and edge type, and chronic inflammatory pseudotumors as a group mimic MSPLs.

Biopsy, Needle↗
PubMed1999

Detection and quantification of coronary artery calcification with electron-beam and conventional CT.

To identify patients with increased risk of having coronary artery disease (CAD), electron-beam computed tomography (EBCT) was used for years for quantifying calcifications of the coronary arteries. The first direct comparison between EBCT and conventional CT was performed to determine the reliability of widely available conventional CT for the assessment of the coronary calcium score. Fifty male patients with suspected CAD were investigated with both modalities, EBCT and conventional 500-ms non-spiral partial scan CT. Scoring of the coronary calcification was performed according to the Agatston method. Forty-two of these patients underwent coronary angiography for the assessment of significant luminal narrowing. The correlation coefficient of the score values of both modalities was highly significant (r = 0.982, p < 0.001). The variability between the two modalities was 42%. Mean calcium score in patients with significant coronary luminal narrowing (n = 37) was 1104 +/- 1089 with EBCT and 1229 +/- 1327 with conventional CT. In patients without luminal narrowing (n = 5) mean calcium score was 73 +/- 57 with EBCT and 26 +/- 35 with conventional CT. Although images of the heart from conventional CT may suffer from cardiac motion artifacts, conventional CT has the potential to identify patients with CAD with accuracy similar to EBCT.

Artifacts↗
PubMed1999

Pediatric liver neoplasms: a radiologic-pathologic correlation.

Only 1-2 % of all pediatric tumors occur in the liver. Two thirds of these tumors are malignant and almost all of the tumors cause clinical symptoms due to their mass effects. Besides the poor prognosis in most of the malignant tumors, for further treatment the origin and nature of the neoplasm has to be known. Due to the mostly unimpeded growth into the peritoneal cavity, the origin of the tumors is primarily often unclear and can non-invasively only be determined by advanced imaging techniques. The display of the macro- and microhistological key features of primary pediatric liver neoplasms, including hepatoblastoma (HB), infantile hemangioendothelioma (IHE), mesenchymal hamartoma (MH), undifferentiated (embryonal) sarcoma (UES), and hepatocellular carcinoma (HCC), together with their imaging representation by ultrasound, computed tomography, and magnetic resonance imaging, may deepen the understanding of the underlying pathology and its imaging appearance. Furthermore, in many cases sufficient information may be provided not only to differentiate benign from malignant tumors, but also to guide for adequate treatment.

Carcinoma, Hepatocellular↗
PubMed1999

Evaluation of the middle and inner ear structures: comparison of hybrid rendering, virtual endoscopy and axial 2D source images.

Recent developments in 3D reconstructions can enhance the quality and diagnostic value of axial 2D image data sets with direct benefits for clinical practice. To show the possible advantages of a hybrid rendering method [color-coded 3D shaded-surface display (SSD)- and volume rendering method] with the possibility of virtual endoscopy we have specifically highlighted the use in relation to the middle and inner ear structures. We examined 12 patients with both normal findings and postoperative changes, using image data sets from high-resolution spiral computed tomography (HRSCT). The middle and inner ear was segmented using an interactive threshold interval density volume-growing method and visualized with a color-coded SSD rendering method. The temporal bone was visualized using a transparent volume rendering method. The 3D- and virtual reconstructions were compared with the axial 2D source images. The evaluated middle and inner ear structures could be seen in their complete form and correct topographical relationship, and the 3D- and virtual reconstructions indicated an improved representation and spatial orientation of these structures. A hybrid and virtual endoscopic method could add information and improve the value of imaging in the diagnosis and management of patients with middle or inner ear diseases making the understanding and interpretation of axial 2D CT image data sets easier. The introduction of an improved rendering algorithm aids radiological diagnostics, medical education, surgical planning, surgical training, and postoperative assessment.

Adult↗
PubMed1999

Multislice MR perfusion imaging and regional myocardial function analysis: complimentary findings in chronic myocardial ischemia.

PURPOSE: The purpose of this study is to assess the reliability of multislice MR perfusion imaging in comparison to regional wall function and nuclear medicine and to test different qualitative and quantitative parameters for perfusion assessment. MATERIAL AND METHODS: 15 patients with chronic myocardial ischemia underwent CINE and first-pass perfusion MR imaging. Functional myocardial imaging was performed using a segmented CINE FLASH sequence and systolic myocardial wall thickening was assessed after semiautomated segmentation. MR first-pass perfusion studies were performed using a multislice saturation recovery TurboFLASH sequence. Different parameters were calculated for assessment of hypoperfused segments and results of MR imaging compared to 99mTc-SestaMIBI SPECT. RESULTS: MR perfusion imaging showed a sensitivity of 72% and a specificity of 98%. In combination with MR CINE imaging and wall thickening analysis we calculated a sensitivity of 100% and a specificity of 93%. Qualitative and quantitative perfusion parameter analysis showed significant differences between normal and hypoperfused segments for the signal intensity increase (p < 0.001), the signal intensity upslope (p < 0.001) as well as for the myocardial mean transit time (p < 0.001). CONCLUSION: The combination of systolic wall thickening analysis and myocardial perfusion can markedly improve the sensitivity of MRI in depiction of LV myocardial perfusion abnormalities. For assessment of hypoperfusion, different quantitative and qualitative parameters can be calculated showing significant differences between normal state and hypoperfusion.

Aged↗
PubMed1999

[Evaluation of right heart load with spiral CT in patients with acute lung embolism].

PURPOSE: Purpose of this study was to evaluate whether spiral-CT allows judgment of right ventricular failure in patients with acute pulmonary embolism. MATERIALS AND METHODS: 61 patients underwent spiral-CT due to suspicion of acute pulmonary embolism. Patients with pulmonary embolism were divided into subpopulations according to the severity of pulmonary embolism in the CT scan. Cardiac measurements were performed on axial spiral-CT images and compared to those of patients without suspicion of pulmonary embolism or cardiac diseases. RESULTS: In 30 patients spiral-CT revealed acute pulmonary embolism. Significant differences in cardiac measurements in patients with severe and less severe pulmonary embolism were found on comparing the following dimensions: left ventricular width (p = 0.0003), left (p = 0.008) and right (p = 0.009) ventricular cross-sectional area, proportion of right to left ventricular width (p = 0.0003) and proportion of right to left ventricular cross-sectional area (p = 0.0001). The proportion of the cross-sectional areas (r = 0.65) and the proportion of the width (r = 0.60) of both ventricles correlated well with the severity of central pulmonary embolism. CONCLUSION: Besides reliable assessment of pulmonary embolism spiral-CT allows the evaluation of cardiac dimensions for judgment of right ventricular failure.

Adult↗
PubMed1999

Coagulative interstitial laser-induced thermotherapy of benign prostatic hyperplasia: online imaging with a T2-weighted fast spin-echo MR sequence--experience in six patients.

PURPOSE: To determine if hypointense lesions clearly outline on T2-weighted fast spin-echo (SE) magnetic resonance (MR) images obtained during coagulative interstitial laser-induced thermotherapy (LITT) of a prostate with benign hyperplasia. MATERIALS AND METHODS: In six patients with benign prostatic hyperplasia (BPH), 12 LITT treatments were followed online with repetitive axial T2-weighted fast SE imaging (repetition time, 3,700 msec; echo time, 138 msec; acquisition time, 19 seconds). Development, time course, correlation with interstitial tissue temperature, and diameters of hypointense lesions around the laser diffusor tip were investigated. Lesion diameters on T2-weighted images acquired during LITT were compared with diameters of final lesions on T2-weighted images and unperfused lesions on enhanced T1-weighted SE images obtained at the end of therapy. RESULTS: Hypointense lesions developed within 20-40 seconds of LITT. Average correlation coefficients between interstitial temperature development and signal intensity development were 0.92 during LITT and 0.90 after LITT. Regression slopes were significantly steeper during LITT (0.67% signal intensity change per degree Celsius) than after LITT (0.47% per degree Celsius; P = .038). Lesions remained visible after LITT for all procedures. Average maximum diameters of lesions were 1-3 mm larger during LITT than after LITT (P = .0006-.019). CONCLUSION: Repetitive T2-weighted fast SE MR imaging during interstitial coagulative LITT of BPH demonstrates the development of permanent hypointense prostate lesions. However, posttherapeutic lesion diameters tend to be overestimated during LITT.

Aged↗
PubMed1999

Electrocardiographically gated thin-section CT of the lung.

PURPOSE: To determine whether electrocardiographic (ECG) gating improves image quality of thin-section computed tomographic (CT) scans of the lung obtained with a subsecond CT scanner. MATERIALS AND METHODS: Thin-section CT was performed in 35 patients by using standard techniques. Three additional sections were obtained in each patient with prospective ECG gating at corresponding levels of the paracardiac lung parenchyma. Non-ECG-gated and ECG-gated sections were then rated in blinded fashion by three experienced radiologists for overall image quality, spatial resolution, and diagnostic value and for different types of respiratory and cardiac motion artifacts. RESULTS: ECG gating helped significantly reduce artifacts caused by cardiac motion (i.e., distortion of pulmonary vessels, double images, or blurring of the cardiac border) (P < .05). ECG gating did not reduce respiratory motion artifacts. In patients with heart rates of less than 76 beats per minute, ECG gating significantly improved overall image quality (P = .041). ECG gating was not perceived to increase the diagnostic value of thin-section CT scans. CONCLUSION: ECG gating improves image quality of thin-section CT scans of the lung by reducing cardiac motion artifacts that may mimic disease. It must be established whether ECG gating can help increase the diagnostic accuracy of thin-section CT for the evaluation of subtle parenchymal disease.

Adult↗
PubMed1999

Memory, empathy, and interactive dimensions of psychoanalytic process.

How is psychoanalysis to deal with its ever widening field of clinical observations and the changing theoretical perspectives that may accompany them--e.g., those concerning intersubjectivity and empathy? Will it be necessary, as some suggest, to modify traditional theory and to abandon related principles of technique such as anonymity and abstinence? Detailed clinical examples of specific interactions are presented to illustrate the interrelated roles of memory, subjective interaction, and empathy. It is suggested that these clinical observations, which encompass newer perspectives, do not require new paradigms. Rather, they can for the present be comfortably accommodated within the purview of older observations, modern cognitive neuroscience, and traditional technical theory.

Adult↗