Biomedical subjects

M Heller

Publications and source records attributed to M Heller.

At least 19 recordsLinked to original sources

PubMed2006

Influence of methods used in body composition analysis on the prediction of resting energy expenditure.

OBJECTIVE: There are considerable differences in published prediction algorithms for resting energy expenditure (REE) based on fat-free mass (FFM). The aim of the study was to investigate the influence of the methodology of body composition analysis on the prediction of REE from FFM. DESIGN: In a cross-sectional design measurements of REE and body composition were performed. SUBJECTS: The study population consisted of 50 men (age 37.1+/-15.1 years, body mass index (BMI) 25.9+/-4.1 kg/m2) and 54 women (age 35.3+/-15.4 years, BMI 25.5+/-4.4 kg/m2). INTERVENTIONS: REE was measured by indirect calorimetry and predicted by either FFM or body weight. Measurement of FFM was performed by methods based on a 2-compartment (2C)-model: skinfold (SF)-measurement, bioelectrical impedance analysis (BIA), Dual X-ray absorptiometry (DXA), air displacement plethysmography (ADP) and deuterium oxide dilution (D2O). A 4-compartment (4C)-model was used as a reference. RESULTS: When compared with the 4C-model, REE prediction from FFM obtained from the 2C methods were not significantly different. Intercepts of the regression equations of REE prediction by FFM differed from 1231 (FFM(ADP)) to 1645 kJ/24 h (FFM(SF)) and the slopes ranged between 100.3 kJ (FFM(SF)) and 108.1 kJ/FFM (kg) (FFM(ADP)). In a normal range of FFM, REE predicted from FFM by different methods showed only small differences. The variance in REE explained by FFM varied from 69% (FFM(BIA)) to 75% (FFM(DXA)) and was only 46% for body weight. CONCLUSION: Differences in slopes and intercepts of the regression lines between REE and FFM depended on the methods used for body composition analysis. However, the differences in prediction of REE are small and do not explain the large differences in the results obtained from published FFM-based REE prediction equations and therefore imply a population- and/or investigator specificity of algorithms for REE prediction.

Absorptiometry, Photon↗

PubMed2006

Detection of small pulmonary nodules in high-field MR at 3 T: evaluation of different pulse sequences using porcine lung explants.

To evaluate two MR imaging sequences for the detection of artificial pulmonary nodules inside porcine lung explants. 67 agarose nodules ranging 3-20 mm were injected into ten porcine lungs within a dedicated chest phantom. The signal on T1-weighted images and radiopacity were adjusted by adding 0.125 mmol/l Gd-DTPA and 1.5 g/l of iodine. A T1-weighted three-dimensional gradient-echo (T1-3D-GRE; TR/TE:3.3/1.1 ms, slice:8 mm, flip-angle:10 degrees ) and a T2-weighted half-Fourier fast-spin echo sequence (T2-HF-FSE; TR/TE:2000/66 ms, slice:7 mm, flip-angle:90 degrees ) were applied in axial orientation using a 3-T system (Intera, Philips Medical Systems, Best, The Netherlands), followed by CT (16x0.5 mm) as reference. Nodule sizes and locations were assessed by three blinded observers. In nodules of >10 mm, sensitivity was 100% using 3D-GRE-MRI and 94% using the HF-FSE sequence. For nodules 6-10 mm, the sensitivity of MRI was lower than with CT (3D-GRE:92%; T2-HF-FSE:83%). In lesions smaller than 5 mm, the sensitivity declined to 80% (3D-GRE) and 53% (HF-FSE). Small lesion diameters were overestimated with both sequences, particularly with HF-FSE. This study confirms the feasibility of 3 T-MRI for lung nodule detection. In lesions greater than 5 mm, the sensitivity of the 3D-GRE sequence approximated CT (>90%), while sensitivity and PPV with the HF-FSE sequence were slightly inferior.

Animals↗

PubMed2006

A method for the estimation of femoral bone mineral density from variables of ultrasound transmission through the human femur.

Quantitative ultrasound (QUS) measurements at peripheral sites can be used to estimate osteoporotic fracture risk. However, measurements at these sites are less suitable to predict bone mineral density (BMD) or fracture risk at the central skeleton. We investigated whether direct QUS measurements at the femur would allow to estimate dual X-ray absorptiometry (DXA) BMD of the total proximal femur with errors comparable to established DXA accuracy errors. Two independent sets of femora were measured in Kiel (6 f, 4 m, age: 55-90) and Paris (19 f, 20 m age: 45-95) using different benchtop systems in the two laboratories. The femora were scanned in transverse transmission mode using focused US transducers of 500 kHz center frequency. The QUS values were averaged over a region similar to the total hip region of dual X-ray absorptiometry (DXA) measurements. BMD was measured using DXA. SOS and BMD correlated significantly (p<0.0001) in both data sets (R2=0.81-0.93). Correlations between BUA and BMD were also significant at p<0.001, but correlation coefficients were lower (R2=0.61-0.75). Residual errors for the estimation of BMD were 8%-10% for SOS as predictor, and 14%-16% for BUA as predictor. The residual error of 8 to 10% for the estimation of BMD from SOS is comparable to variabilities among different DXA femur subregions and accuracy errors of femoral DXA measurements caused by the impact of soft tissue. It is substantially smaller than the errors of 13% for the estimation of total femur BMD from spine BMD, 14% for the estimation of total femur BMD from calcaneus SOS or 16% for the estimation of ash weight from DXA. The results of the study show that SOS is able to predict total BMD with adequate accuracy. If femoral BMD could be obtained in vivo with comparable accuracy, femoral QUS would be suited for the assessment of bone status at one of the main osteoporotic fracture sites.

Absorptiometry, Photon↗

PubMed2006

Balloon angioplasty of arteries of the upper extremities in patients with extracranial giant-cell arteritis.

OBJECTIVES: To evaluate the outcome of balloon angioplasty in the arteries of the upper extremities in patients with giant-cell arteritis (GCA) and stenosing extracranial involvement. METHODS: Percutaneous transluminal angioplasty (PTA) for symptomatic upper limb artery stenoses (n = 29) and occlusions (n = 1) resistant to medical treatment was carried out in 10 patients (all women, mean age 65 years) with GCA. Vascular lesions were located in the subclavian (n = 4), axillary (n = 10) and brachial (n = 16) arteries. Interventional treatment was accompanied by immunosuppressive drugs in all patients. Follow-up included clinical and serological examination, magnetic resonance angiography and colour duplex ultrasound. RESULTS: Initial technical success of angioplasty was achieved in the case of all vascular lesions. In five patients, marked recurrent stenoses (vascular territories; n = 10/30) were found during follow-up (mean 24 months). The cumulative primary patency rate was 65.2%. All recurrent lesions developed in the territories of the initial long-segment stenoses. Repeated PTA (vascular territories, n = 8; patients, n = 5) provided a cumulative secondary patency rate of 82.6% and a cumulative tertiary patency rate of 89.7%. CONCLUSIONS: Despite a tendency to restenoses, balloon angioplasty of the upper-extremity artery, in combination with immunosuppressive treatment, is an efficient method for the treatment of extracranial GCA.

Aged↗

PubMed2006

[Parametric biomedical imaging--what defines the quality of quantitative radiological approaches?].

Quantitative parametric imaging approaches provide new perspectives for radiological imaging. These include quantitative 2D, 3D, and 4D visualization options along with the parametric depiction of biological tissue properties and tissue function. This allows the interpretation of radiological data from a biochemical, biomechanical, or physiological perspective. Quantification permits the detection of small changes that are not yet visually apparent, thus allowing application in early disease diagnosis and monitoring therapy with enhanced sensitivity. This review outlines the potential of quantitative parametric imaging methods and demonstrates this on the basis of a few exemplary applications. One field of particular interest, the use of these methods for investigational new drug application studies, is presented. Assessment criteria for judging the quality of quantitative imaging approaches are discussed in the context of the potential and the limitations of these methods. While quantitative parametric imaging methods do not replace but rather supplement established visual interpretation methods in radiology, they do open up new perspectives for diagnosis and prognosis and in particular for monitoring disease progression and therapy.

Algorithms↗

PubMed2006

[Does interventional therapy prolong the patency of hemodialysis fistulas and grafts?].

PURPOSE: To retrospectively evaluate procedural success and patency after endovascular treatment of acute dysfunctional hemodialysis fistulas and grafts in a non-preselected patient cohort. MATERIALS AND METHODS: 185 angiographies of hemodialysis fistulas and grafts on the upper extremities were analyzed for 120 patients (53 male, 67 female; mean-age 63.1 +/- 11.4, range 24 - 91). 70 % (n = 130) were native arteriovenous fistulas, 17 % (n = 31) were prosthetic grafts, and 13 % (n = 24) were non-specific. In total, 278 lesions requiring endovascular treatment were detected. 13 % (n = 35) of the lesions were located in the arterial inflow, 18 % (n = 49) in native arteriovenous anastomoses, 7 % (n = 19) in prosthetic grafts and 62 % (n = 171) in the venous outflow. The primary, secondary and cumulative patency after endovascular treatment was calculated. RESULTS: In 51 % (n = 94) of the cases endovascular treatment could be performed, in 8 % (n = 14) no lesion requiring treatment was detected, and in 42 % (n = 77) intervention was not considered possible. In 45 % (n = 124) of the detected lesions endovascular treatment was successful, in 18 % (n = 51) the intervention failed, and in 37 % (n = 103) intervention was not considered possible. The complication rate was 5 % (n = 10). The primary, secondary, and cumulative patency rates for 50 % of the hemodialysis fistulas and grafts after endovascular treatment were 65, 191, and 370 days, respectively. The results differed significantly from each other with p < 0.05 in the log rank test and log rank trend test. CONCLUSION: Endovascular treatment of acute dysfunctional hemodialysis fistulas and grafts is effective in restoring the patency for hemodialysis.

Acute Disease↗

PubMed2006

Reproducible Simulation of Respiratory Motion in Porcine Lung Explants.

PURPOSE: To develop a model for exactly reproducible respiration motion simulations of animal lung explants inside an MR-compatible chest phantom. MATERIALS AND METHODS: The materials included a piston pump and a flexible silicone reconstruction of a porcine diaphragm and were used in combination with an established MR-compatible chest phantom for porcine heart-lung preparations. The rhythmic inflation and deflation of the diaphragm at the bottom of the artificial thorax with water (1 - 1.5 L) induced lung tissue displacement resembling diaphragmatic breathing. This system was tested on five porcine heart-lung preparations using 1.5T MRI with transverse and coronal 3D-GRE (TR/TE = 3.63/1.58, 256 x 256 matrix, 350 mm FOV, 4 mm slices) and half Fourier T2-FSE (TR/TE = 545/29, 256 x 192, 350 mm, 6 mm) as well as multiple row detector CT (16 x 1 mm collimation, pitch 1.5, FOV 400 mm, 120 mAs) acquired at five fixed inspiration levels. Dynamic CT scans and coronal MRI with dynamic 2D-GRE and 2D-SS-GRE sequences (image frequencies of 10/sec and 3/sec, respectively) were acquired during continuous "breathing" (7/minute). The position of the piston pump was visually correlated with the respiratory motion visible through the transparent wall of the phantom and with dynamic displays of CT and MR images. An elastic body splines analysis of the respiratory motion was performed using CT data. RESULTS: Visual evaluation of MRI and CT showed three-dimensional movement of the lung tissue throughout the respiration cycle. Local tissue displacement inside the lung explants was documented with motion maps calculated from CT. The maximum displacement at the top of the diaphragm (mean 26.26 [SD 1.9] mm on CT and 27.16 [SD 1.5] mm on MRI, respectively [p = 0.25; Wilcoxon test]) was in the range of tidal breathing in human patients. CONCLUSION: The chest phantom with a diaphragmatic pump is a promising platform for multi-modality imaging studies of the effects of respiratory lung motion.

Animals↗

PubMed2006

Value of fat-suppressed proton-density-weighted turbo spin-echo sequences in detecting meniscal lesions: comparison with arthroscopy.

PURPOSE: To evaluate fat-suppressed (FS) proton-density-weighted (PDw) turbo spin-echo (TSE) magnetic resonance imaging (MRI) compared to arthroscopy in the detection of meniscal lesions. MATERIAL AND METHODS: In a prospective study, 31 knee joints were imaged on a 1.5T MR scanner before arthroscopy using the following sequences: (a) coronal and sagittal FS-PDw TSE (TR/TE: 4009/15 ms); (b) coronal T1w SE (TR/TE: 722/20 ms), and sagittal PDw TSE (TR/TE: 3800/15 ms). Other imaging parameters were: slice thickness 3 mm, FOV 160 mm, matrix 256 x 256. A total of 186 meniscal regions (62 menisci; anterior horn, body, posterior horn) were evaluated. Standard of reference was arthroscopy. Sensitivity, specificity, negative predictive value (npv), positive predictive value (ppv), and accuracy were calculated. RESULTS: Arthroscopically, meniscal lesions were detected in 55/186 segments (35 medial and 20 lateral meniscal lesions). Sensitivity, specificity, npv, ppv, and accuracy for combination of coronal and sagittal FS PDw TSE were 91.4%, 98.3%, 95%, 97%, and 93.5% for the medial meniscus, and 90%, 98.6%, 97.3%, 94.7%, and 96.8% for the lateral. The results were comparable to the combination of coronal T1w SE and sagittal PDw TSE for the medial (88.6%, 98.3%, 93.4%, 96.9%, 91.4%) and the lateral (90%, 95.9%, 97.2%, 85.7%, 92.5%) meniscus. CONCLUSION: FS PDw TSE-MR sequences are an excellent alternative for the detection of meniscal lesions in comparison with diagnostic arthroscopy.

Adolescent↗

PubMed2005

Effect of hepatitis C infection on tacrolimus doses and blood levels in liver transplantation recipients.

BACKGROUND: In our cohort of patients with hepatitis-C virus, which is the most common indication for liver transplantation, we have noted higher relative blood levels of tacrolimus compared to patients without hepatitis-C virus. AIM: To verify this observation and determine its clinical significance, we performed a comparison of doses and blood levels of tacrolimus in hepatitis-C virus and non- hepatitis-C virus liver transplantation recipients. METHODS: Tacrolimus dose and trough level, as well as mean alanine aminotransferase, for all patients transplanted at our center with a deceased donor between 1/1995 and 12/1999 with hepatitis-C virus were recorded at monthly intervals during the first 24 months following transplantation and compared to patients without hepatitis-C virus. RESULTS: The tacrolimus levels for hepatitis-C virus and non-hepatitis-C virus patients were not significantly different at any of the monthly intervals, except month 9. In addition, the overall mean tacrolimus levels for hepatitis-C virus and non-hepatitis-C virus patients were not significantly different (P = ns). However, the mean tacrolimus dose (mg/kg) was significantly higher for hepatitis-C virus patients at 12, 15, 18, 21 and 24 months, P < 0.01. The total mean tacrolimus dose in hepatitis-C virus patients was lower during year one by 39% (P = 0.018) and by 73% (P = 0.001) during year two. The total difference in cost of tacrolimus (for year one and two) administered to hepatitis-C virus patients was $4920, P = 0.03. The serum alanine aminotransferase was significantly higher in hepatitis-C virus patients at each monthly interval except month 1, P < or = 0.01. CONCLUSIONS: Liver transplant recipients with hepatitis-C virus require significantly lower oral doses of tacrolimus to achieve the same blood levels compared to non-hepatitis-C virus patients. This difference may result in a significant reduction in the cost of tacrolimus in hepatitis-C virus patients. The most likely explanation for these findings is decreased hepatic clearance of tacrolimus caused by mild hepatic injury from recurrent hepatitis-C virus.

Dose-Response Relationship, Drug↗

PubMed2005

Fast T1- and T2-weighted pulmonary MR-imaging in patients with bronchial carcinoma.

PURPOSE: A prospective study to evaluate the diagnostic potential and limitations of three fast MRI sequences in patients with bronchial carcinoma based on the comparison with spiral CT. MATERIAL AND METHODS: Three fast chest MRI sequences from 20 patients with central or peripheral bronchial carcinoma were evaluated by two observers for relation of tumour to adjacent structures, lymph node enlargement, additional pulmonary lesions and artefacts. The information from MR-imaging was compared with the results from spiral CT. MRI comprised a T1-3D-GRE breath-hold examination ("VIBE", TR/TE 4.5/1.9 ms, flip-angle 12 degrees , matrix 502 x 512, 2.5 mm coronal slices), a breath-hold, T2-HASTE sequence (TR/TE 2000/43 ms, matrix 192 x 256, 10 mm coronal slices) and a respiration-triggered T2-TSE sequence (TR/TE 3000-6000/120 ms, matrix 270 x 512, 6 mm transverse slices). The FOV was adapted individually (380-480 mm). RESULTS: The presence of the primary bronchial carcinoma and infiltration of thoracic structures by tumour tissue could be demonstrated by all sequences. VIBE sequence was more suitable for detecting small pulmonary nodules than the other MRI examinations, but compared to CT still 20% of these lesions were missed. Contrary to VIBE and T2-weighted TSE scans, HASTE sequence was limited in imaging mediastinal lymph nodes due to missing relevant findings in 2/20 patients. HASTE images significantly provided the lowest rate of artefacts in imaging lung parenchyma (P < 0.001 in peripheral parenchyma), but spatial resolution was limited in this sequence. Concerning the differentiation between tumour and adjacent atelectasis (n = 8), T2-weighted TSE imaging was superior to CT and VIBE in all cases and to HASTE sequence in 4/8 patients. CONCLUSION: The combination of VIBE and HASTE sequence allows for an adaequate imaging of thoracic processes in patients with bronchial carcinoma, limited only in visualizing small pulmonary nodules. To obtain more detail resolution and to differentiate tumour tissue from adjacent atelectasis, T2-TSE examination may be added in selected cases.

Aged↗

PubMed2005

[Comparison of spine injuries by means of CT and MRI according to the classification of Magerl].

PURPOSE: A feasibility study of the classification of spine injuries by CT and MRI data according to the classification of Magerl for spine injuries. MATERIAL AND METHODS: In 39 patients, 46 injured vertebrae were evaluated by means of CT and MRI. A single-slice helical CT (Somatom Plus S, Siemens, Erlangen, Germany) was used with a collimation and feed of 2 mm and 3 mm, respectively. Sagittal reformations were reconstructed from these data sets. MR imaging was performed with 1.5T and 1.0T machines (Magnetom Vision and Magnetom Impact, Siemens). Transverse and sagittal T1-w SE- images as well as sagittal T2-w TSE- and STIR-images were generated. Each fractured vertebra was independently categorized two times according to the classification of Magerl on the basis of CT- and MRI-images. The CT- and MRI-classifications were subsequently compared. RESULTS: Most fractures were classified as impaction fractures (A1) or burst fractures (A3). Only 5/46 injuries of vertebrae were not given the same classification by means of CT and MRI (r = 0.9). MRI showed more bony lesions than CT (n. s., p > 0.05) and was able to evaluate ruptures of the longitudinal ligaments in 5 patients. CONCLUSION: Classification of spine injuries according to the Magerl-classification showed a significant agreement between CT and MRI and therefore a comparable evaluation of stability. MRI was superior in delineating ligamental lesions.

Adolescent↗

PubMed2005

Myelodysplastic syndrome associated with trisomy 2.

Clinical course and cytogenetic analysis suggest that myelodysplasia (MDS) is one step in a multistep model of malignant transformation of haematopoietic stem cells to acute myeloid leukaemia (AML). We report a further case of MDS associated with trisomy 2, and comment on the significance of the cytogenetic abnormality, which as a sole abnormality only occurs in MDS, but is found in combination with other chromosomal abnormalities in AML. Previous reports on balanced and unbalanced chromosomal abnormalities associated with therapy related MDS and therapy related AML suggest that trisomy 2 is an early chromosomal abnormality in leukaemogenesis.

Aged↗

PubMed2004

Detection of dysbaric osteonecrosis in military divers using magnetic resonance imaging.

This was a controlled cross-sectional study to investigate the prevalence of dysbaric osteonecrosis (DON) in military divers. MRI examinations of the large joints and adjacent bones were performed in a cross-sectional group of 32 highly experienced military divers and 28 non-divers matched for age and anthropometric data. Additional plain radiographs and follow-up controls were performed in all persons with signs certain or suspicious of DON. In two subject groups (one of divers and one of non-divers), lesions characteristic of DON were detected. From this controlled study, it may be concluded that MRI is a highly sensitive method to detect signs of osteonecrosis. It could be shown that the prevalence of bone lesions characteristic of osteonecrosis in highly experienced military divers is not higher than in non-diving subjects of comparable age. The outcome of this comparably small study group fits to the results of previous extensive studies performed with radiographs. The detected low incidence of DON in this collective may be due to the fact that military divers follow stricter selection criteria, decompression schemes and medical surveillance than commercial divers.

Adult↗

PubMed2004

Effect of organ and tissue masses on resting energy expenditure in underweight, normal weight and obese adults.

BACKGROUND: In normal-weight subjects, resting energy expenditure (REE) can be accurately calculated from organ and tissue masses applying constant organ-specific metabolic rates. This approach allows a precise correction for between-subjects variation in REE, explained by body composition. Since a decrease in organ metabolic rate with increasing organ mass has been deduced from interspecies comparison including human studies, the validity of the organ- and tissue-specific REE calculation remains to be proved over a wider range of fat-free mass (FFM). DESIGN: In a cross-sectional study on 57 healthy adults (35 females and 22 males, 19-43 y; 14 underweight, 25 intermediate weight and 18 obese), magnetic resonance imaging (MRI) and dual-energy X-ray absorptiometry (DXA) were used to assess the masses of brain, internal organs, skeletal muscle (MM), bone and adipose tissue. REE was measured by indirect calorimetry (REEm) and calculated from detailed organ size determination by MRI and DXA (REEc1), or in a simplified approach exclusively from DXA (REEc2). RESULTS: We found a high agreement between REEm and REEc1 over the whole range of FFM (28-86 kg). REE prediction errors were -17 +/- 505, -145 +/- 514 and -141 +/- 1058 kJ/day in intermediate weight, underweight and obese subjects, respectively (n.s.). Regressing REEm on FFM resulted in a significant positive intercept of 1.6 MJ/day that could be reduced to 0.5 MJ/day by adjusting FFM for the proportion of MM/organ mass. In a multiple regression analysis, MM and liver mass explained 81% of the variance in REEm. DXA-derived REE prediction showed a good agreement with measured values (mean values for REEm and REEc2 were 5.72 +/- 1.87 and 5.82 +/- 1.51 MJ/day; difference n.s.). CONCLUSION: Detailed analysis of metabolically active components of FFM allows REE prediction over a wide range of FFM. The data provide indirect evidence for a view that, for practical purposes within humans, the specific metabolic rate is constant with increasing organ mass. Nonlinearity of REE on FFM was partly explained by FFM composition. A simplified REE prediction algorithm from regional DXA measurements has to be validated in future studies.

Absorptiometry, Photon↗

PubMed2004

[Quantitative ultrasound for the diagnosis of osteoporosis].

Quantitative ultrasound (QUS) methods are promising tools for the assessment of the bone status in osteoporosis. The techniques are based on changes in speed and amplitude of a broadband ultrasound signal propagating through the bone. However, ultrasound propagation through the anisotropic bone is complex and cannot be described in a simple way. The devices are easy to use, inexpensive, portable, do not use ionizing radiation, and therefore have advantages compared to conventional densitometry. This review discusses the technical basics, current research, clinical applications, points of weakness, and future prospects of QUS. For better understanding ultrasound propagation through bone is visualized with a simulation software.

Bone and Bones↗

PubMed2004

Ex-vivo injection technique for implanting solid pulmonary nodules into porcine lungs for multi-slice CT.

PURPOSE: To develop a method for generating realistic pulmonary nodules that equal small pulmonary metastases and granulomas. MATERIALS AND METHODS: A total of 70 artificial lesions were introduced into 5 inflated porcine lungs inside a dedicated chest phantom by high pressure injection of a fat-wax-Lipiodol mixture and scanned with 16-slice computed tomography (CT). Image evaluation by two experienced radiologists included analysis of morphology, nodule size and density. RESULTS: The median nodule density was 78.8 Hounsfield units (HU), with 54 of 70 nodules (77.14 %) judged typical of small lung metastases. CONCLUSION: Without inducing visible damage of lung parenchyma, the injection technique produces highly realistic pulmonary nodules for morphometry or nodule detection with CT.

Animals↗

PubMed2004

[Inflammatory aortic arch syndrome: contrast-enhanced, three-dimensional MR angiography in stenotic lesions].

PURPOSE: To determine the value of contrast-enhanced, three-dimensional MR angiography for the evaluation of stenotic and occlusive vascular lesions in inflammatory aortic arch syndrome. MATERIALS AND METHODS: 14 patients with inflammatory aortic arch syndrome (giant cell arteritis: n = 8, Takayasu arteritis: n = 4, ankylosing spondylitis: n = 1 sarcoidosis: n = 1) underwent MR angiography of the aortic arch and the supra-aortic vessels (n = 15, 2 patients were examined twice) and of the abdominal aorta (n = 2). MRA was performed using a 3D-FLASH sequence (TR/TE 4.6/1.8 ms, flip angle 30 (3)) on a 1.5T system. MRA imaging was compared with the findings of DSA, which served as gold standard. RESULTS: In a total of 467 examined vascular territories, DSA revealed 50 stenoses and 35 occlusions. All lesions were detected by MRA. In 23 segments, the degree of stenosis was overestimated by MRA. Sensitivity and specificity of MRA were 100 % and 94.3 %, positive and negative predictive values were 73.6 and 100 %, and the accuracy was 95.1 %. CONCLUSIONS: Despite a tendency to overestimate stenoses, contrast-enhanced three-dimensional MR angiography is a valid, non-invasive technique in the assessment of inflammatory aortic arch syndrome.

Adult↗

PubMed2004

[The role of magnetic resonance imaging in the preoperative evaluation of the peripancreatic vasculature in pancreas carcinoma].

PURPOSE: To evaluate the accuracy of magnetic resonance angiography (MRA) to predict vascular involvement in pancreas carcinoma. MATERIALS AND METHODS: This prospective trial included 42 patients with suspected pancreas carcinoma. All patients underwent MRA, different tomographic sequences (MRI) and surgery. Peripancreatic vessels were analyzed for vascular involvement, with the tumor infiltration graded on a scale of 0 to 4 (grade 0 - 4). The imaging findings were correlated with surgery and histopathology. RESULTS: The sensitivity of MRA to predict vascular involvement was 61 % (19 of 31 evaluated vessels) and the specificity 97 % (148 of 153). Sensitivity and specificity for axial MRI were both 94 % (29 of 31 and 144 of 153 evaluated vessels). The difference in the sensitivities of MRA and MRI was statistically significant (p < 0.01). Vascular involvement was correctly graded in 58 % (18 of 31) by MRA and in 74 % (23 of 31) by MRI. CONCLUSION: MRA alone is not sufficient to diagnose vascular involvement in pancreas carcinoma, but provides an adequate overview of the vascular anatomy. A combined protocol of MRA and MRI is needed for an acceptable evaluation of the peripancreatic vessels.

Aged↗