Search PubMed⌕ Search

Biomedical subjects

K-F Kreitner

Publications and source records attributed to K-F Kreitner.

At least 19 recordsLinked to original sources
PubMed2005

[MR imaging of tendon diseases. Exemplified using the examples of rotator cuff, epicondylitis and achillodynia].

Diseases of tendons have recently increased in importance. This may be due to the increasing popularity of free time sport, but also to the increasing number of treatment possibilities. The origin of damage to the tendons can be explained by a series of mechanisms, of which reduced tissue perfusion and mechanical irritation with microtrauma, which lead to degeneration, can be considered as the most important. Imaging diagnostics plays a significant role in the diagnosis and planning of the therapy of such illnesses. In addition to the conventional x-ray to determine the position of the joint and bony structures, ultrasound can be used to examine the tendons, bursae and tissue.MRI is an excellent method for examining the pathology of tendons due to its exceptional qualities for imaging tissue and joints as well as its high specificity. Using MRI, it is possible to determine the degree of morphological change, make reproducible examinations, as well as determining comorbidity factors or the reasons for the changes early in the illness. It therefore influences surgical decisions and can play a key role in the planning of operations. MRI arthography can-depending on the question-increase the diagnostic power in cases of alterations in the rotator cuff.

Achilles Tendon↗
PubMed2005

[Contribution of early systole to total antegrade flow volume in breath-hold phase-contrast flow measurements].

PURPOSE: To evaluate the contribution of early systole for the assessment of antegrade aortic flow volume by breath-hold velocity-encoded magnetic resonance (MR) flow measurements. MATERIALS AND METHODS: Expiratory breath-hold fast low-angle shot (FLASH) phase-contrast flow measurements (temporal resolution tRes 61 msec, shared phases) perpendicular to the proximal ascending aorta and short axis true fast imaging with steady-state precession (TrueFISP) cine MR ventriculometry (tRes 34.5 msec) were performed in ten healthy male volunteers on a 1.5 T MR system (Sonata, Siemens Medical Solutions). Antegrade aortic flow volume (AFV) and left ventricular stroke volume (LV-SV) were evaluated using Argus Ventricular Function and Argus Flow Software, version MR 2002B (Siemens Medical Solutions). A beta release of Argus Flow MR 2004A allowed interpolation of the flow up-slope during early systole to the preceding R-wave trigger. The respective intraindividual median differences between the AFV of each flow evaluation and LV-SV as well as between both AFV measurements were calculated and compared using the sign test for paired samples. RESULTS: Non-interpolated AFV significantly deviated from LV-SV (p = 0.006), underestimating the latter by 13.1 mL (13 %). Interpolating aortic flow during early systole significantly increased AFV by 10.8 mL (13 %) compared to the flow evaluation which did not take early systole into account (p = 0.006). AFV with interpolation of early systolic flow agreed well with LV-SV (median difference - 3.0 mL or - 3 %, respectively), and no significant difference between these measurements was found (p = 1.0). CONCLUSION: Flow during early systole contributes substantially to total forward flow volume in the ascending aorta. Interpolation of the early systolic up-slope is therefore recommended for the evaluation of breath-hold phase-contrast flow measurements.

Adult↗
PubMed2005

[Systematic analysis of the geometry of a defined contrast medium bolus--implications for contrast enhanced 3D MR-angiography of thoracic vessels].

PURPOSE: Little is known about the dispersion of a defined contrast bolus during its passage through the heart and pulmonary vasculature. The purpose of this study was to analyze factors influencing a defined contrast bolus for ce-MRA of thoracic vessels. MATERIALS AND METHODS: For analysis of bolus geometry, an ECG-gated saturation-recovery Turbo-Flash sequence with a TI of 20 msec was used. It was acquired axially at the level of the pulmonary trunc, so that with one data acquisition a curve analysis was possible in the ascending and descending aorta, and in the pulmonary trunc. Twenty-nine patients received 3 ml of Gd-DTPA diluted with saline to a total of 20 ml. Contrast injection was done using a MR compatible power injector with injection rates varying between 1, 2 and 4 ml/sec. Each injection was followed by a saline flush of 20 ml with the same injection rate and mode. Cardiac function was assessed by cine imaging, and phase contrast measurements. After normalization to baseline signal intensity (SI), bolus curves were fitted using a gamma-variate fit and peak signal intensity (peak SI), time-to-peak (TP), upslope, mean transit time (MTT) and dispersion of the contrast bolus were calculated. Furthermore, T (1) and [Gd] in the experimental setting were calculated as follows: T (1) = T (1 o)/ ln [SI/SI (0)], and [Gd] (exp) = [1/T (1) - 1/T (1 o)]/ R (1.) They were then extrapolated [Gd] to clinical conditions by [Gd] (clin) = [Gd] (exp) . 10/1.5, and minimal blood T (1) by T (1)(clin) = 1 / [1/T (1 o) + R (1) [Gd] (clin)]. RESULTS: With increasing injection rate, there was a significant decrease (p < 0.001) of MTT in all target vessels. However, this decrease was not linear: a 4-fold increase in injection rate lead to a 2-fold decrease in MTT e. g. in the ascending aorta. MTT was significantly shorter in the pulmonary trunc compared with that in the ascending and descending aorta (p < 0.001), regardless of injection rate (p < 0.001). Vice versa, dispersion of the contrast bolus was significantly lower in the pulmonary trunc, and increased with higher injection rates. There was no clinically relevant difference in minimal blood T (1) between the different target vessels, for clinical conditions extrapolated values ranged between 20 und 79 msec. Heart function parameters only had a minor influence of bolus curve parameters. CONCLUSION: Analysis of bolus geometry enables determination of transit times of a defined contrast bolus through a defined target vessel in the thoracic cavity. Bolus geometry is mainly determined by injection parameters, cardiac function is of minor importance. Dispersion of contrast bolus and MTT increase from the pulmonary trunc to the ascending aorta. The knowledge of these facts may help optimizing of injection parameters and the total amount of contrast agent for contrast-enhanced MRA of thoracic vessels.

Adult↗
PubMed2004

Assessment of right ventricular function by 16-detector-row CT: comparison with magnetic resonance imaging.

The purpose of this study was to determine right ventricular (RV) function from 16-detector-row CT by using two different software tools in comparison with MRI. Nineteen patients underwent cardiac CT. (1) With semiautomated contour detection software end-diastolic and end-systolic RV volumes were determined from short-axis CT reformations (MPR) created at every 10% of the RR-interval. (2) End-systolic and end-diastolic axial images were transformed to 3D to determine the volumes by using a threshold-supported reconstruction algorithm. Steady-state free-precession cine-MRI of the heart was done in short-axis orientation. RV function could not be analyzed in one patient because of sternal wire artifacts in MRI. Mean end-diastolic (155.4+/-54.6 ml) and end-systolic (79.1+/-37.0 ml) RV volumes determined with MPR correlated well with MRI [151.9+/-53.7 ml (r=0.98) and 75.0+/-36.0 ml (r=0.96), respectively (P<0.001)]. RV stroke volume (76.2+/-20.2 ml for MPR-CT, 76.9+/-20.7 ml for MRI, r=0.93) showed a good correlation and RV ejection fraction (50.8+/-8.4% for MPR-CT, 51.9+/-7.4% for MRI, r=0.74) only a moderate one. Threshold supported 3D reconstructions revealed insufficient correlations with MRI (r=0.31-0.59). MPR-based semiautomated analysis of cardiac 16 detector-row CT allows for RV functional analysis. The results correlate well with MRI findings. Threshold value-supported 3D reconstructions did not show satisfying results because of inhomogeneities of RV contrast enhancement.

Aged↗
PubMed2004

[Contrast-enhanced 3D MR perfusion of the lung: application of parallel imaging technique in healthy subjects].

PURPOSE: Evaluation of lung perfusion by contrast-enhanced 3D MRI using partial parallel imaging techniques. MATERIALS AND METHODS: Eight healthy volunteers were examined using a contrast-enhanced dynamic FLASH 3D sequence with partial parallel imaging technique at 1.5 T MRI with a TA of 1.5 sec. The whole lung was covered by 36 coronal slices. A ventral, middle and dorsal slice of each lung was manually segmented and signal-to-time curves were computed. For absolute quantification of blood flow through the right and left pulmonary artery, phase-contrast flow measurements were performed. RESULTS: No significant difference was found between the signal intensity in the right (8.9 +/- 2.6) and left (8.0 +/- 3.5) lung, corresponding to a left-to-right signal intensity ratio of 0.9. A significantly higher signal intensity was found in the dorsal regions of the lungs (p = 0.01) compared to the ventral regions. The time to peak of the signal intensity was significantly shorter in the dorsal (15.3 sec) and middle (15.7 sec) regions of the lungs (p = 0.03 and p = 0.04, respectively) than in the ventral regions (16.3 sec). The ratio between blood flow through the left (2.2 L/min) and right (2.7 L/min) lung was 0.84. CONCLUSION: Partial parallel image acquisition can assess the perfusion of the lungs at high temporal resolution. The perfusion is slightly higher on the right than on the left. The signal increases faster and has a higher peak in the dorsal lung regions.

Adolescent↗
PubMed2004

[Contrast-enhanced 3D MR angiography of the pulmonary arteries with integrated parallel acquisition technique (iPAT) in patients with chronic-thromboembolic pulmonary hypertension CTEPH - sagittal or coronal acquisition?].

PURPOSE: Comparison of two different types of contrast-enhanced 3D-MR angiography (CE-MRA) with integrated parallel acquisition technique (iPAT) in patients with chronic-thromboembolic pulmonary hypertension (CTEPH) and evaluation whether sagittal acquisition with higher resolution and minimized acquisition time is superior to common coronal orientation. MATERIALS AND METHODS: CE-MRA was performed on 15 patients with CTEPH preoperatively and on 10 patients also postoperatively, while 5 other patients received only a postoperative MRA. All 30 MR studies with one coronal and two sagittal acquisitions were blindly evaluated and compared. The resolution of coronal and sagittal MRA was 1.3 x 0.6 x 1.4 mm (3) and 1.2 x 1.2 x 1.2 mm (3), and acquisition time 20 and 17 sec (iPAT factor 2, GRAPPA), respectively. Image quality, coverage of the pulmonary arteries, delineation of patent segmental and sub-segmental vessels and pathological findings were assessed. A total of 1980 vessels were evaluated. RESULTS: Sagittal 3D-MRA was superior in overall image quality and complete coverage of the vessels compared to coronal MRA, 18 % of subsegmental and 4.3 % of segmental arteries as well as 1.1 % of the lobar vessels were not covered by coronal acquisition. Only 0.5 % of sagittal subsegments were missed. The number of depicted patent segmental and subsegmental arteries was higher in sagittal MRA (460 vs 489 and 573 vs 649, respectively), the total difference of patent vessels was 105. Sagittal MRA revealed more pathological findings in segmental arteries (especially thrombotic material and stenoses). CONCLUSION: Sagittal CE-MRA of the pulmonary arteries with higher resolution and short acquisition time proved to be superior in all assessed criterias like image quality, vessel coverage, depiction of patent peripheral arteries and pathological findings compared to coronal MRA. The applied sagittal MRA is recommended for the routine practise in diagnostic evaluation of patients with CTEPH.

Chronic Disease↗
PubMed2004

[Software-assisted CT-postprocessing of the carotid arteries].

PURPOSE: A software assistant for automatic evaluation of CT-angiograms (CTA) was developed. It should enable the visualization of the vessel lumen and the quantitative evaluation of a stenosis. CTA examinations of patients with suspected carotid artery stenoses were used for the evaluation of the software assistant. MATERIALS AND METHODS: Twelve Patients with suspected high-grade stenosis of the carotid arteries underwent a CTA examination using a multislice CT scanner. The data were analyzed and evaluated using the new software assistant. The results were compared with the data of digital subtraction angiography (DSA) of these patients. RESULTS: The time of digital postprocessing with the new software-assistant took about six minutes on average. Contour extraction of the vessel, MIP and curved MPR (c-MPR) and orthogonal cross-sectional images of the vessels were calculated, followed by an automatic quantification of stenosis by the use of the c-MPR. A good correlation was found between CTA and DSA data regarding the stenosis grade (r = 0.82). Furthermore, some information could be provided about the plaque morphology. CONCLUSION: The software-assisted detection and analysis of carotid artery stenosis with the new developed program is possible within a justifiable time. DSA- and CTA-data did not show a significant difference in stenosis grading. Further development of software tools could lead to a better characterization of plaque morphology.

Carotid Arteries↗
PubMed2004

[Comparison of contrast-enhanced MR angiography of the aortoiliac vessels using a 1.0 molar contrast agent at 1.0 T with intra-arterial digital subtraction angiography].

PURPOSE: To evaluate the diagnostic accuracy of contrast-enhanced MR angiography (CE-MRA) using a 1.0 molar contrast agent at 1.0 T for the diagnosis of abdominal aortic aneurysms and stenoses of renal or iliac arteries in comparison to intraarterial digital subtraction angiography (DSA). MATERIALS AND METHODS: A total of 19 patients with the suspicion of abdominal aortic aneurysm or stenosis of renal or iliac arteries were examined with CE-MRA at 1.0 T. Intra-arterial DSA served as reference in all cases. After test bolus tracking, 10 or 8 ml of the 1.0 molar contrast agent Gadobutrol corresponding to a dose of 0.1 - 0.15 mmol/kg bw were injected and imaging performed using a FLASH-3D sequence. To evaluate the interobserver-variability, the blinded images were analyzed by two radiologists. Besides the rating of overall image quality on a 4-point-scale, the images were evaluated for aneurysms and arteriosclerotic lesions with a stenosis of < 50 % or > 50 % or occlusion. RESULTS: A total of 144 segments were analyzed. The mean value of the CE-MRA image quality was 3.4 on a 4-point-scale. The sensitivity of CE-MRA in depicting relevant pathological findings was 96 % and the specificity 99 %. The positive predictive value was 96 % and the negative predictive value 99 %. Inter-observer variability was low with a kappa value of 0.82. CONCLUSION: CE-MRA using a 1.0 molar contrast agent at 1.0 T enables an excellent diagnosis or exclusion of pathologies of the aortoiliac vessels.

Adult↗
PubMed2004

[Non-invasive assessment of coronary artery bypass grafts -- an update].

The limited lifetime and the correlation between graft occlusion and recurring symptoms underline the need for repeated imaging of coronary artery bypass grafts. CT and MRI allow for non-invasive imaging of coronary bypasses with high accuracies concerning the patency of these vessels. Multidetector CT seems to be the CT technique of choice, especially after the introduction of 16 slice CT scanners for morphologic assessment of coronary artery bypass grafts. Compared with MRI, CT is a robust technique for assessment of cardiac anastomoses, native coronary arteries, and for the detection of graft stenoses. MRI, however, is able to deliver functional information about the grafts and the recipient coronary arteries by determining the coronary flow reserve. Furthermore, it can be integrated in a multiparametric MR examination protocol. The follow-up of asymptomatic patients can primarily be done by these non-invasive techniques as nearly every third patient reveals an asymptomatic bypass occlusion 5 years after operation. Furthermore, patients with atypical complaints after the operation may undergo non-invasive imaging as long as documented patency of the bypass averts coronary angiography. Patients with recurrent angina pectoris and/or myocardial ischemia discovered by other cardiologic tests have to undergo coronary angiography.

Coronary Artery Bypass↗
PubMed2004

[CT-angiography with a 16-row CT scanner for perioperative evaluation of the hepatic arteries].

PURPOSE: To evaluate the efficiency of CT angiography (CTA) with 16-row MSCT compared with MR angiography (MRA) in analyzing the arterial anatomy in patients undergoing liver surgery. MATERIALS AND METHODS: In 30 patients, MRA and CTA studies of the abdominal vessels were reviewed. CT parameters: slice thickness 3 mm; collimation 1.5; reconstruction interval 2 mm (Philips MX 8000 IDT); 120 ml contrast media (400 mg/ml) at a rate of 4 ml/sec; acquisition of arterial-phase scans. The anatomy of the hepatic artery was evaluated from axial and reconstructed maximum-intensity-projection (MIP) images ("Slab-Viewer", Philips). MR parameters: contrast-enhanced coronal FLASH-3D sequences; slice thickness 1.4 mm; TR 3.47, TE 1.3; 1.5 T scanner (Siemens Somatom). Image quality was rated with a scoring system. Contrast enhancement of the hepatic artery and the liver parenchyma was measured. RESULTS: The image quality of CTA was rated as excellent in 18 (MRA 5); good in 8 (MRA 22); satisfactory in 4 patients (MRA 3), and non-diagnostic in 0 patient (MRA 1). Compared to MRA, the image quality of CTA was better in 15/30 patients; equal for both in 13 and worse in 2 patients. CTA provided a better depiction of the segmental branches of the hepatic arteries in 15/30 patients and revealed important anatomic variations of the hepatic artery in 8/30 patients. These variations were not be seen in MRA: e. g., MRA missed a left gastric arterial supply to the left liver. The ratio of contrast enhancement in liver parenchyma and hepatic artery was 4.7 in CTA and 4.5 in MRA. CONCLUSION: CTA with multislice scanners delivers better image quality and depiction of the hepatic arteries than MRA. Thus, MRI of the hepatic arteries can be replaced by routine CT, which is already part of the preoperative evaluation for liver transplantation.

Angiography↗
PubMed2004

[Assessment of global and regional left ventricular function with a 16-slice spiral-CT using two different software tools for quantitative functional analysis and qualitative evaluation of wall motion changes in comparison with magnetic resonance imaging].

PURPOSE: To determine global and regional left ventricular (LV) function from retrospectively gated multidetector row computed tomography (CT) by using two different semiautomated analysis tools and to correlate the results with those of magnetic resonance imaging (MRI). MATERIALS AND METHODS: Nineteen patients (5 females, 14 males, mean age 69 years) underwent 16-slice spiral-CT (MS-CT) with standard technique without administration of beta-blockers for a decrease in the cardiac rate. Ten series of images were reconstructed at every 10 % of the RR-interval. With commercially available software capable of semiautomated contour detection, end-diastolic and end-systolic LV volumes (EDV and ESV) were determined from short-axis multiplanar CT reformations (MPR). Axial images of the end-systolic and end-diastolic cardiac phase were transformed to 3D volumes (3D) to determine EDV and ESV by using a threshold-supported reconstruction algorithm dependent on the contrast enhancement of the left ventricle. Steady-state free-precession cine MR images were acquired in short-axis orientation on the same day in all but one patient. Regional wall motion was assessed qualitatively in 17 left ventricular segments and classified as normo-, hypo-, a- or dyskinetic. Bland-Altman analysis was performed to calculate limits of agreement and systematic errors between CT and MRI. RESULTS: For MPR/3D, mean end-diastolic (144.4/142.8 mL +/- 67.5/67.1) and end-systolic (66.4/68.7 mL +/- 52.1/49.9) LV volumes as determined with MS-CT correlated well with MRI measurements (147.6 mL +/- 67.6 [ r = 0.98/0.96] and 73.3 mL +/- 55.5 [ r = 0.98/0.98], respectively [ p <.001]). LV stroke volume (77.6/74.1 +/- 19.2/23.4 mL for CT vs. 74.4 mL +/- 18.4 for MRI, r = 0.92/0.74) and LV ejection fraction (58.6/55.9 % +/- 13.5/13.7 for CT vs. 55.6 % +/- 13.5 for MRI, r = 0.95/0.91) also showed good correlation (p <.001). Regional wall motion analysis revealed agreement between CT and MRI in 316/323 (97.8 %) myocardial segments. CONCLUSION: Semiautomated analysis of 16-detector row CT data sets enables global and regional volumetric and functional analysis. The CT results correlate well with MRI findings for short axis MPR and for 3D volume reconstructions, with a higher statistical spread for the 3D method. The underestimation of end-systolic and end-diastolic volumes with CT may be caused by partial volume averaging due to the lower temporal resolution as compared with MRI.

Aged↗
PubMed2003

Rapid musculoskeletal magnetic resonance imaging using integrated parallel acquisition techniques (IPAT)--initial experiences.

PURPOSE: To investigate the feasibility of using multiple receiver coil elements for time saving integrated parallel imaging techniques (iPAT) in traumatic musculoskeletal disorders. MATERIAL AND METHODS: 6 patients with traumatic derangements of the knee, ankle and hip underwent MR imaging at 1.5 T. For signal detection of the knee and ankle, we used a 6-channel body array coil that was placed around the joints, for hip imaging two 4-channel body array coils and two elements of the spine array coil were combined for signal detection. All patients were investigated with a standard imaging protocol that mainly consisted of different turbo spin-echo sequences (PD-, T (2)-weighted TSE with and without fat suppression, STIR). All sequences were repeated with an integrated parallel acquisition technique (iPAT) using a modified sensitivity encoding (mSENSE) technique with an acceleration factor of 2. Overall image quality was subjectively assessed using a five-point scale as well as the ability for detection of pathologic findings. RESULTS: Regarding overall image quality, there were no significant differences between standard imaging and imaging using mSENSE. All pathologies (occult fracture, meniscal tear, torn and interpositioned Hoffa's cleft, cartilage damage) were detected by both techniques. iPAT led to a 48 % reduction of acquisition time compared with standard technique. Additionally, time savings with iPAT led to a decrease of pain-induced motion artifacts in two cases. CONCLUSION: In times of increasing cost pressure, iPAT using multiple coil elements seems to be an efficient and economic tool for fast musculoskeletal imaging with diagnostic performance comparable to conventional techniques.

Adolescent↗
PubMed2003

[Measurement of the AT and the CCD angle of macerated cadaver femora: a comparative study between CT and MRI measurements].

PURPOSE: To compare measurements of the real AT (femoral antetorsion) and CCD (caput-collum-diaphysis) angle by computed tomography (CT) and magnetic resonance imaging (MRI) of hip specimen using direct measurements as reference standard, and to show that measurement by MRI can replace CT measurements and may help avoiding X-ray exposition. MATERIALS AND METHODS: CT and MRI measurements were obtained on 25 in water-arrested macerated human femora. Postprocessing was done by 4 independent readers on a workstation using a dedicated 3D-software. Direct measurements of the real AT and the CCD angle were used as reference standard. The analysis included Student's t test for paired values, interobserver variability using intra-class correlation coefficients (ICC), maximum and middle divergence of the angles, and Bland-Altman plots. RESULTS: For determining AT and the CCD angle with CT and MRI, good correlation was found between the 4 readers and with measurements using the reference standard. ICCs were 0.97 and 0.90 for measuring AT and CCD angle with CT, and 0.95 and 0.71 for measurements with MRI, respectively. Mean divergence between CT measurements and those of the reference standard was 0.8 degrees for AT and 0.7 degrees for the CCD-angle. Mean divergence between MRI measurements and those of the reference standard was 0.3 degrees for AT and -0.4 degrees for the CCD-angle. Mean divergences between CT and MRI measurements of AT and CCD-angle were 0.5 degrees. Neither systematic errors nor dependences on the qualitative size of the reference data were evident in the divergences of measurements. CONCLUSION: Measurements of the real AT and CCD angle by CT and MR imaging revealed a good correlation with direct measurements of the femoral specimen and consequently can be recommended for clinical use. MRI measurements can replace CT measurements, avoiding X-ray exposure especially in young patients undergoing preoperative evaluation for hip dysplasia.

Bone Malalignment↗
PubMed2003

[Pre- and postoperative assessment of hemodynamics in patients with chronic thromboembolic pulmonary hypertension by MR techniques].

PURPOSE: To evaluate the potential of MRI to grade cardiac impairment and pulmonary hypertension in patients with chronic thromboembolic pulmonary hypertension (CTEPH) in comparison with invasive pressure measurements before and after surgery. MATERIALS AND METHODS: We examined 35 patients with CTEPH before and after pulmonary thromboendarterectomy (PTE). For assessment of hemodynamics, velocity-encoded segmented GE-sequences (pulmonary arteries and ascending aorta) and segmented cine GE-sequences along the short axis of the heart were performed. The analysis comprised calculation of ejection fractions, peak velocities, mean pulmonary arterial flow and vessel diameter. 10 volunteers served as controls. Flow measurements were compared to invasively measured mean pulmonary arterial pressure (MPAP) and vascular resistance (PVR). RESULTS: Compared to volunteers, CTEPH-patients showed significantly reduced right ventricular ejection fractions (p < 0.001), pulmonary peak velocity (p < 0.001) and significantly increased diameters of the pulmonary arteries (p < 0.001). The flow measurements in the aorta (2713 ml/min) and the pulmonary arteries (2088 ml/min) revealed a large bronchopulmonary shunt. After PTE, there was a significant reduction in vessel diameter (p < 0.001). This was associated with a significant increase in pulmonary peak velocities (p < 0.001). The increase in pulmonary peak velocities correlated with the decrease of PVR (r = 0.5) and MPAP (r = 0.6). The ejection fraction of the right ventricle correlated with PVR (r = 0.6) and MPAP (r = 0.7). The postoperative decrease in MPAP correlated with the increase in right ventricular ejection fraction (r = 0.8). After PTE there was no bronchopulmonary shunt volume. All patients had an inverse motion of the interventricular septum. It returned to normal in 68 % of patients after surgery. CONCLUSION: Breath-hold MR-techniques enable non-invasive assessment of pulmonary hemodynamics in patients with CTEPH. For postoperative follow-up studies MRI could be considered the modality of choice.

Adult↗
PubMed2002

Low-field MR arthrography of the shoulder joint: technique, indications, and clinical results.

In the age of cost containment and urgent reductions in health care expenditures, new options have to be explored to satisfy both diagnostic requirements and economic limitations. The introduction of low-field MR systems for assessment of joint disorders seemed to be an option for lower costs. The purpose of this article is to summarize available experiences with low-field MR arthrography of the glenohumeral joint with respect to image quality and diagnostic accuracy in detecting labral and rotator cuff lesions. Up to now, there has been only a limited number of studies available dealing with low-field MR arthrography of the glenohumeral joint. They reveal that, despite a minor image quality in comparison with high-field imaging, low-field MR arthrography of the shoulder allows for sufficient evaluation of intra- and extra-articular structures in the detection of major abnormalities such as glenohumeral instability or rotator cuff disease. Furthermore, open-configured MR scanners enable kinematic studies: Besides the analysis of normal motion, pathological findings in patients with instabilities and impingement syndrome can be delineated. They further offer the possibility for performing MR imaging-guided arthrography of the shoulder. This was first described using an open C-arm scanner with a vertically oriented magnetic field so that MR arthrography may be performed in one setting.

Arthrography↗
PubMed2002

[Preliminary results of coronary artery examination using a 3D-navigator sequence on a high performance MR system].

PURPOSE: To evaluate MR coronary angiography using a three-dimensional navigator echo sequence on a MR scanner with a high performance gradient system. MATERIAL AND METHODS: Five healthy volunteers were examined with a 1.5 Tesla MR system, using a high performance prototype gradient system (peak amplitude 50 mT/m, rising time 600 mus). For imaging, a navigated gradient-echo pulse sequence with an in-plane resolution between 0.63 x 0.63 and 0.78 x 0.78 mm2 was used. Per patient two overlapping slabs were acquired. The number of visualized coronary artery segments was estimated (AHA classification). In addition, signal-to-noise measurements were performed in the ascending aorta at the level of the proximal right and left coronary arteries. RESULTS: In all volunteers the left main, the right coronary artery up to segment 3, the LAD up to segment 8 and the RCX with segment 11 and 13 were clearly visualized. The average signal-to-noise value at the level of the right coronary artery was 11.4 +/- 5.0, at the level of the left coronary artery 12.3 +/- 4.5. One volunteer was measured with an in-place resolution of 0.63 x 0.63 mm2. This resulted in a too low signal-to-noise ratio so that an adequate assessment of coronary arteries was no longer possible. CONCLUSION: 3D-MR coronary angiography using the navigator technique is limited by the signal-to-noise ratio.

Adult↗
PubMedDate not supplied

[Osteoporosis and osteoarthritis--is there really an inverse relation?].

OBJECTIVE: Increasing bone mineral density (BMD) has been found in several studies in patients with osteoarthritis (OA). Therefore, the simultaneous occurrence of osteoporosis (OP) and OA is denied by many clinicians. Because of our clinical impression, however, we suggest that we have to consider a common occurrence. In the present study we have examined the relationship between osteoathritis of the knee or the hip and osteoporosis. METHOD: The BMD of the lumbar spine and the proximal femur of 117 OA patients (82 postmenopausal female patients aged 50-83 and 35 male patients aged 36-86 years) who subsequently required hip or knee replacements, but were otherwise healthy, was measured by dual-energy X-ray absorptiometry (DXA; Hologic QDR-2000). The results are given as required by the WHO and the new German guidelines of the DVO. The BMD was measured and categorised in a sex-related manner and the occurrence of disuse osteoporosis on the affected limb was examined. Furthermore, a comparison was made in the level of BMD between the OA of the involved hip or knee. RESULTS: There was a high occurrence of low BMD among the patients. 23.2 % of the women were affected by OP. This reflects the normal distribution of OP in the female population. 20 % of the male patients had occult OP. This is astonishingly high. Osteopenia was measured for 37.1 % of the male patients and 42.7 % of the female patients. Age proved to be a significant factor in the degree of BMD. Neither a disuse osteoporosis, nor a significance in the OA-affected joint to the degree of BMD, could be proven. CONCLUSION: We cannot support the hypotheses that OA prevents OP. Moreover, the occurrence of OP in our study reflected the incidence of OP in the average female and was astonishingly high in the male population; this does not support the hypothesis that the two conditions are mutually exclusive. Also a lower risk of fractures among OA patients cannot be concluded. There is current open discussion whether a known BMD should influence the decision for a cemented or an uncemented prosthesis.

Adult↗