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Biomedical subjects

Claus D Claussen

Publications and source records attributed to Claus D Claussen.

At least 19 recordsLinked to original sources
PubMed2004

Noninvasive detection of coronary lesions using 16-detector multislice spiral computed tomography technology: initial clinical results.

OBJECTIVES: The aim of our study was to evaluate the feasibility of detecting coronary artery lesions using a new computed tomography (CT) scanner with 16 detectors and faster gantry rotation. BACKGROUND: Computed tomography angiography of the coronaries permits assessment of the coronaries; however, image quality is still impaired by motion artifacts and calcifications. METHODS: Sixty patients scheduled for conventional coronary angiography (CCA) were additionally studied by multislice spiral computed tomography (MSCT). Calcium scores and a contrast-enhanced visualization of the coronaries were performed and analyzed regarding evaluability, presence of coronary artery lesions, and correct clinical diagnosis. RESULTS: Calcium scoring was successful in all patients; 58 of 60 patients had a diagnostic contrast-enhanced scan. Mean calcium score was 506 +/- 743 Agatston score equivalent (ASE); 13 of 58 (22%) patients had an ASE >or=1,000, 46 of 58 (78%) patients <1,000. In 763 coronary segments, CCA detected a total of 75 lesions >or=50%. The MSCT correctly assessed 54 of these. Twenty-one lesions were missed or incorrectly underestimated. Sensitivity was 72%, specificity 97%. When restricting analysis to patients with an ASE <1,000, 40 significant lesions >or=50% were seen on CCA, and MSCT correctly detected 39 lesions (sensitivity 98%, specificity 98%). Regardless of any threshold, the correct clinical diagnosis could be obtained in 58 of 60 (97%) of all patients. CONCLUSIONS: In individuals with low-to-moderate amounts of coronary artery calcium, 16-detector CT coronary angiography has high sensitivity and specificity for the diagnosis of significant coronary artery stenosis.

Adult↗
PubMed2004

Synchronous gastrointestinal and musculoskeletal manifestations of different subtypes of inflammatory myofibroblastic tumor: CT, MRI and pathological features.

We describe a case of an unusual multicentric appearance of an inflammatory myofibroblastic tumor, consisting of multiple gastrointestinal masses with different growth patterns and simultaneous, distant, musculoskeletal manifestations. CT and MR imaging features demonstrated a different degree of lesion enhancement, which proved histologically to be related to an alternation of predominantly spindle cell areas with a myxoid-vascular IMT subtype. A clear separation of the imaging characteristics of this tumor's subtypes by correlation with the pathology was not possible because of the mixed histologic character of the tumor in all its locations. However, MRI signal in the T2-weighted sequence was lower in the spindle cell variant localized predominantly in the musculoskeletal system, while the gastrointestinal predominantly myxoid-vascular counterparts showed slightly higher signal in the T2-weighted sequence.

Aged↗
PubMed2004

Solitary pulmonary nodules: dynamic contrast-enhanced MR imaging--perfusion differences in malignant and benign lesions.

PURPOSE: To determine whether dynamic contrast material-enhanced magnetic resonance (MR) imaging with use of kinetic and morphologic parameters reveals statistically significant differences between malignant and benign solitary pulmonary nodules. MATERIALS AND METHODS: Fifty-eight patients met the inclusion criteria of a solitary 5-40-mm pulmonary nodule without calcification or fat at computed tomography. Fifty-one patients were examined successfully; 46 received a histologic diagnosis, and five received a diagnosis by means of observation over 2 years. Dynamic MR images were acquired every 10 seconds for a total of 4 minutes. Diagnostic characteristics for differentiation were examined by using threshold values for maximum peak enhancement, slope of enhancement, and washout. Receiver operating characteristic curves were calculated to test the usefulness of these parameters. The diagnostic performance of a combination of curve profiles and morphologic contrast material distribution were tested by using a decision tree. RESULTS: Frequency of malignancy was 53% (27 of 51 nodules). Malignant nodules showed stronger enhancement with a higher maximum peak and a faster slope (P <.001). Significant washout (>0.1% increase in signal intensity per second) was found only in malignant lesions (14 of 27 lesions). Sensitivity, specificity, and accuracy were 96%, 88%, and 92%, respectively, for maximum peak; 96%, 75%, and 86% for slope; and 52%, 100%, and 75% for washout. When curve profiles and morphologic enhancement patterns were combined, sensitivity increased to 100%. CONCLUSION: Dynamic MR imaging delineates significant kinetic and morphologic differences in vascularity and perfusion between malignant and benign solitary pulmonary nodules. Washout seems to be highly specific for malignancy.

Adult↗
PubMed2004

Diagnostic accuracy of multidetector computed tomography coronary angiography in patients with angiographically proven coronary artery disease.

OBJECTIVES: The aim of the present study was to evaluate the diagnostic accuracy in detecting high-grade coronary stenoses in patients with known coronary artery disease (CAD) using multidetector computed tomography (MDCT). BACKGROUND: The MDCT systems with electrocardiographic (ECG)-gating permit visualization of the coronary arteries. However, severe calcifications and higher heart rates are known to degrade image quality and limit correct diagnosis. METHODS: Sixty-six patients with proven CAD as assessed by conventional coronary angiography (CCA) were studied by MDCT (mean time 24 months postangiography). Total calcium score and all coronary arteries, including distal segments and side branches, were assessed with respect to evaluability, presence of high-grade coronary artery stenoses (>70%), and correct diagnosis. Results were compared to CCA. RESULTS: A total of 105 lesions were detected by CCA. The MDCT correctly detected 39 lesions (sensitivity 37%, specificity 99%). The correct clinical diagnosis could be obtained in 24 patients (36%). Artifacts due to elevated heart rates or severe coronary artery calcification were the main cause of degraded image quality inhibiting correct diagnosis. In 21/66 patients (32%) all four major coronary vessel segments could be visualized. A threshold for maximum heart rate and a maximum calcification level were established (65 beats/min and an Agatston Score Equivalent of 335, respectively). A second analysis was made using these thresholds. Of all patients studied, 10/11 (91%) were correctly diagnosed when adhering to these thresholds. CONCLUSIONS: When using MDCT as a noninvasive diagnostic modality to assess advanced CAD, it appears to be mandatory to preselect patients in order to achieve reliable results.

Adult↗
PubMed2004

The role of [(18)F] FDG-PET, CT/MRI and tumor marker kinetics in the evaluation of post chemotherapy residual masses in metastatic germ cell tumors--prospects for management.

The purpose of this study was to assess the ability of [(18)F]FDG-PET, CT/MRI and serum tumor marker (TM) to predict the viability of residual masses after high-dose chemotherapy (HD-Ctx) in patients with metastatic germ cell tumors (GCT). In a prospective study, 60 residual tumors in 28 GCT patients were classified as viable/nonviable by FDG-PET, CT/MRI and TM levels. The results were validated either by histological examination of a resected mass and/or biopsy or by clinical/radiological follow-up for at least 6 months. There were no significant differences among the sensitivities observed with PET, CT/MRI and TM, but PET was significantly more specific than CT/MRI in predicting residual mass viability. TM showed the highest specificity. The highest accuracy in classification of residual tumors was achieved by a combination of PET, CT/MRI and TM (area under the ROC curve =0.91). All mature teratomas showed false-negative PET results with SUVs in the same range as necrosis. For classification of residual masses after HD-Ctx of metastatic GCT, [(18)F]FDG-PET is a valuable diagnostic method to complement the established procedures CT and TM. Positive PET results are highly correlated with the presence of viable tumor, but residual masses with negative PET findings still require resection. In cases of tumor progression diagnosed by CT and elevated TM, additional PET examinations are without benefit. PET seems useful in patients with stable disease or partial remission in CT/MRI and normalized TM as well as in marker-negative disease.

Adult↗
PubMed2004

Multislice first-pass myocardial perfusion imaging: Comparison of saturation recovery (SR)-TrueFISP-two-dimensional (2D) and SR-TurboFLASH-2D pulse sequences.

PURPOSE: To compare signal-to-noise ratio (SNR), contrast-to-noise (CNR) ratio, and diagnostic accuracy of a newly developed saturation recovery (SR)-TrueFISP-two-dimensional (2D) sequence with an SR-TurboFLASH-2D sequence. MATERIALS AND METHODS: In seven healthy subjects and nine patients with coronary artery disease (CAD), contrast-enhanced perfusion imaging (with Gd-DTPA) was performed with SR-TrueFISP and SR-TurboFLASH sequences. Hypoperfused areas were assessed qualitatively (scale = 0-4). Furthermore, SNR and CNR were calculated and semiquantitative perfusion parameters were determined from signal intensity (SI) time curves. Standard of reference for patient studies was single-photon emission computer tomography (SPECT) and angiography. RESULTS: The perception of perfusion deficits was superior in TrueFISP images (2.6 +/- 1.0) than in TurboFLASH (1.4 +/- 0.6) (P < 0.001). Phantom measurements yielded increased SNR (143 +/- 34%) and CNR (158 +/- 64%) values for TrueFISP. In patient/volunteer studies SNR was 61% to 100% higher and signal enhancement was 110% to 115% higher with TrueFISP than with TurboFLASH. Qualitative and semiquantitative assessment of perfusion defects yielded higher sensitivities for detection of perfusion defects with TrueFISP (68% to 78%) than with TurboFLASH (44% to 59%). CONCLUSION: SR-TrueFISP-2D perfusion imaging provides superior SNR and CNR than TurboFLASH imaging. Moreover, the dynamic range of SIs was found to be higher with TrueFISP, resulting in an increased sensitivity for detection of perfusion defects.

Adult↗
PubMed2004

Clinical evaluation of a computer simulated prediction model of contrast enhancement of the liver in spiral CT.

OBJECTIVE: A software program was developed simulating a compartmental model of blood circulation based on differential equations. The aim of this study was to compare software-simulated levels of hepatic enhancement with the true values in patients and to test how many patients reach the simulated hepatic enhancement level. METHODS: As software program the CT application software carebolus 2 (Siemens, Forchheim, Germany) was used. Hepatic contrast-enhancement curves were simulated prior to CT examinations to evaluate a patient specific time delay after contrast application. At the time delay, when the simulation curve showed an enhancement threshold of 40 Hounsfield Units (HU), the CT spiral scan was started applying 120 ml contrast media with 2 ml/s. The simulated curves were compared with the empiric curves of each patient. RESULTS: 25 of 28 patients (89%) achieved 40 HU. The mean enhancement of empiric patients curves was 46.32 +/- 11.9 HU, the mean simulated enhancement was 46.62 +/- 4.3 HU S.D. (P= 0.48). 4.4 values per patient liver could be compared with the simulation curve (122 points for 28 patients): 50% of the patient curves were within a range of 5 HU compared with the simulation curve. CONCLUSION: Software simulation of contrast enhancement curves of the liver is a feasible and valuable method to predict individual liver enhancement curves. Improvements concerning the integration of cardiovascular parameters and preexisting liver parenchymal diseases into the simulation software have to be arranged.

Adult↗
PubMed2004

The effects of paclitaxel on the three phases of restenosis: smooth muscle cell proliferation, migration, and matrix formation: an in vitro study.

PURPOSE: We sought to evaluate the growth-modulating potential of paclitaxel on cultured human arterial smooth muscle cells depending on the administered dose. MATERIAL AND METHODS: For all experiments human arterial smooth muscle cells (SMCs) were used. SMCs were either cultured for 5 days or for 20 days with paclitaxel (doses: 10(-7) M, 10(-8) M, 10(-9) M). For a total period of 20 days, proliferation kinetics of the SMC were analyzed. To assess the clonogenic activity of the SMC colony-forming assays were performed. Drug- and dose-dependent cell cycle changes were analyzed by flow cytometry. The effect on cell migration was examined in a 2-chamber migration system. The effects of paclitaxel on the synthesis of tenascin were examined via immunofluorescence. RESULTS: Depending on the dose administered, paclitaxel proved to inhibit SMC proliferation effectively when administered during the total period of 20 days. When incubated for 5 days with doses of paclitaxel ranging between 10(-8) M and 10(-9) M, SMCs showed clear signs of regeneration. When being incubated with 10(-7) M of paclitaxel, however, SMCs reacted with a reduction in cell proliferation, a reduced clonogenic activity, and a drug-induced G2/M phase block. SMC migration was inhibited effectively as well as extracellular matrix formation. CONCLUSION: Paclitaxel is a potent inhibitor of SMC proliferation, SMC migration, and extracellular matrix formation in vitro, with all three phases of the restenosis process inhibited effectively.

Angioplasty, Balloon↗
PubMed2004

Semiquantitative assessment of myocardial perfusion using magnetic resonance imaging: evaluation of appropriate thresholds and segmentation models.

RATIONALE AND OBJECTIVES: The aim of the study was to determine optimal thresholds for semiquantitative perfusion parameters and to evaluate the influence of different segmentation models in detecting malperfused regions. MATERIAL AND METHODS: In 6 healthy subjects and 13 patients with coronary artery disease, contrast-enhanced first-pass perfusion imaging was performed using a SR-TrueFISP-sequence. Thresholds for semiquantitative parameters were established, and different segmentation models of the left ventricular myocardium were tested. The standard of reference for patient studies was single photon emission computed tomography. RESULTS: Optimal thresholds were determined in healthy subjects for the perfusion parameters upslope, AUC, and peak SI of mv-0.5*std, mv-1.5*std, and mv-1.0*std, respectively. Using the optimal threshold for each parameter/segmentation combination sensitivities and specificities of stress studies were between 66% and 93% and 77% and 92%, respectively. Subdivision of radial segments into subendo/subepicardial segments increased sensitivities for perfusion deficits. CONCLUSIONS: Subdivision of radial myocardial segments is essential in analysis of magnetic resonance first-pass perfusion series. Semiquantitative perfusion parameters possess different sensitivities for the detection of perfusion deficits.

Adult↗
PubMed2004

Magnetic resonance imaging characteristics of six radiofrequency electrodes in a phantom study.

PURPOSE: To evaluate and compare visibility and artifacts in magnetic resonance (MR) compatible radiofrequency (RF) electrodes for MR-guided RF ablation. MATERIAL AND METHODS: Six different MR compatible electrodes for RF ablation including two internally cooled single needles, one internally cooled cluster needle, two expandable needles and one perfused needle were tested in a phantom study at 0.2 Tesla and at 1.5 Tesla field strength. Fluoroscopic, T1- and T2-weighted fast spin echo (FSE) and gradient echo (GE) sequences, which are usually used for MR-guided interventions, were evaluated. Qualitative and quantitative evaluations were performed. Length, width, noise, tip artifacts, global artifacts and global visualization of the RF electrodes that showed all sequences at different angles. RESULTS: Qualitative analysis showed that electrodes were well visualized at all angles and sequences and on both MR imagers. Quantitative analysis showed that artifact-induced widening of the shaft was increased in all electrodes by: a). use of fluoroscopic sequences, GE sequences, and fat saturation, b). increasing the angle between the needle and main magnetic field, and c). high field strength (1.5 T). Expandable needles produced fewer tip artifacts but broader signal voids along the shaft compared to nonexpandable needles. Cluster electrodes produced less widening than the other electrodes. CONCLUSION: Visibility and artifacts in all six MR compatible RF electrodes are satisfactory and these electrodes could be used for MR-guided radiofrequency ablation procedures.

Artifacts↗
PubMed2004

Radiopacity of current endovascular stents: evaluation in a multiple reader phantom study.

PURPOSE: To evaluate the radiopacity of endovascular stents based on the fluoroscopy mode in a phantom of the human pelvis. MATERIALS AND METHODS: The following stents were included in this study: Medtronic AVE Bridge, Medtronic AVE Bridge X, Cordis Covered Nitinol (Covent), Guidant Dynalink, Luminexx, Guidant Megalink, Memotherm Flexx, Palmaz Medium, Palmaz-Schatz Long-Medium, Palmaz Corinthian PQ394Q and PQ294Q, SelfX, SMART without markers, SMART with radiopaque markers, Easy Wallstent. To evaluate radiopacity, images of the stents placed in four different positions (lumbosacral junction left and right, iliosacral joint left and right) of a pelvic phantom were taken at the following modes: spotfilm, continuous fluoroscopy, 15 pulses per second, 7.5 pulses per second, and 3 pulses per second. Images were presented at random to four independent readers and radiopacity scores were assessed: 0 = not visible, 1 = poor visibility, 2 = average visibility, 3 = good visibility, and 4 = very good visibility. RESULTS: The Covent stent had the highest overall radiopacity score (3.25), followed by the Luminexx (3.04) and the Medtronic AVE Bridge X (2.74) stents. At the spotfilm mode, the best visible stents were the Medtronic AVE Bridge X, the Covent and the Easy Wallstent stents and at the continuous fluoroscopy mode, the Covent, the Luminexx, and the Medtronic AVE Bridge X stents. Decreasing the fluoroscopy mode went hand in hand with a reduction of the radiopacity scores of all stents. At the standard fluoroscopy mode of 7.5 pulses per second, the Covent stent was seen well or very well in 96.9%, followed by the Luminexx (76.9%), and the Medtronic AVE Bridge X (41.25%) stents. CONCLUSIONS: Stent radiopacity directly depends on the fluoroscopy mode; if the pulse frequency decreased, detecting the stents became more difficult. Stent mass correlates with stent radiopacity (e.g., Cordis Covered Nitinol, Bridge X). Radiopaque markers may improve stent radiopacity dramatically (e.g., Luminexx vs Memotherm Flexx).

Blood Vessel Prosthesis Implantation↗
PubMed2004

Radiofrequency ablation: in vivo comparison of four commercially available devices in pig livers.

PURPOSE: To compare in vivo coagulation necrosis obtained with four radiofrequency (RF) ablation devices, to determine shape and reproducibility of induced coagulation by means of three-dimensional measurements of the ablation zone, and to achieve representations of the coagulated areas in three-dimensional spaces. MATERIALS AND METHODS: Four commercially available RF devices (perfusion, internally cooled cluster, and nine- and 12-tine expandable electrodes) that represent the most widely used systems on the market were tested. Sixteen in vivo ablation procedures were performed in porcine livers (four ablations for each RF system). After macroscopic and histopathologic analyses of 3-mm-thick liver sections, morphometric and volumetric findings in the central zone of white coagulation necrosis were assessed. Coagulation volume, diameter, length, and shape were determined digitally. After analysis of variance, measurements with each system were tested with the Tukey post hoc test. RESULTS: Mean coagulation volumes were 31.5 cm3 +/- 15.8 (SD) for the perfusion electrode, 20.5 cm3 +/- 2.6 for the cluster electrode, 16.2 cm3 +/- 7.3 for the 12-tine electrode, and 9.8 cm3 +/- 3.2 for the nine-tine electrode (P <.05, perfusion vs nine-tine electrode). No significant differences were observed regarding the mean short axis perpendicular to the needle shaft: 2.30 cm +/- 0.94, 3.04 cm +/- 0.26, 3.44 cm +/- 0.21, and 2.70 cm +/- 0.76, respectively. Variation coefficients were 0.50, 0.13, 0.45, and 0.33, respectively. CONCLUSION: Larger coagulation volumes were obtained with the perfusion and internally cooled cluster devices. More spherical volumes of ablation were achieved with the 12-tine and cluster electrodes. The former proved superior with regard to the short axis perpendicular to the needle shaft. The cluster and nine-tine electrode produced better reproducibility, which is suggestive of improved predictability of the extent of coagulation with these systems.

Animals↗
PubMed2004

Computed tomographic colonography (CTC): Possibilities and limitations of clinical application in colorectal polyps and cancer.

Colorectal cancer is the second leading cause of cancer-related deaths in Europe and the United States. Most colorectal cancers develop from adenomatous polyps over a number of years. Early detection of polyps eliminates the risk of subsequent carcinomas. Computed tomographic (CT) colonography is a diagnostic technique detecting colorectal neoplasms. With the introduction of multidetector-row computed tomography (MD-CT), CT colonography (CTC) has gained influence as a new diagnostic tool in early detection of colonic pathologies by acquiring volumetric CT data sets of the abdomen. This volumetric data is analyzed using CTC workstations, which provide an interactive display of 2D and 3D images of the colon. In several studies, CTC revealed a high accuracy (sensitivity/patient: 83-100% and specificity/patient: 93-100%) in detecting pathological colonic changes. Furthermore, CTC is an excellent diagnostic technique for the evaluation of patients with incomplete conventional colonoscopy and allows the assessment of extracolonic abdominal and pelvic organs. In this article, the status of CT colonography as a method of detecting colonic polyps and colorectal carcinomas using single- and multidetector-row CT will be reviewed.

Adenomatous Polyposis Coli↗
PubMed2004

Preoperative marking of musculoskeletal tumors guided by magnetic resonance imaging.

BACKGROUND: The purpose of this study was to evaluate a new stereotactic method for preoperative coil-marking of musculoskeletal tumors with use of interventional magnetic resonance imaging. METHODS: Nine patients with a soft-tissue or bone-marrow tumor were referred to our department for preoperative marking of the extent of the lesion. In one patient, two lesions were marked. Guidance for the punctures and the delivery of the coils was provided by an open low-field magnetic resonance imaging system with horizontal access. After imaging of the extent of the lesion, magnetic resonance imaging-compatible titanium coils were placed with use of nearly real-time or step-by-step magnetic resonance imaging control. The coils were placed up to seventy-two hours before the surgery. The inclusion of the tumor borders within the area of the excision was examined with cross-sectional histological analysis of surgical specimens. RESULTS: The tumor-marking intervention was successfully performed with the guidance of magnetic resonance imaging only in all patients. Preoperatively, nineteen coils were used to mark the ten lesions in the nine patients. All of the coils were easily located with intraoperative fluoroscopy. No coil migrated between the time of the percutaneous marking and the surgery. Histological examination of the resection borders revealed no residual tumor cells. No complications were observed, and, after a mean of twenty-three months of follow-up, no tumor had recurred. CONCLUSIONS: Preoperative coil-marking guided by magnetic resonance imaging for exact delineation of a musculoskeletal tumor is technically feasible and can readily demonstrate the full extent of the tumor. Use of magnetic resonance fluoroscopy reduces the time needed for the intervention. We recommend the coil-marking technique.

Adult↗
PubMed2003

The value of SPET/CT in chronic osteomyelitis.

Immunoscintigraphy with technetium-99m labelled anti-granulocyte antibodies (AGA) is an equivalent technique to imaging with in vitro-labelled leucocytes, which is now considered state of the art in the diagnostic work-up of patients with suspected post-traumatic chronic osteomyelitis. In this study, we evaluated the use of a combined single-photon emission tomography/computed tomography (SPET/CT) device to improve detection and anatomical definition of inflammatory bone lesions. Twenty-seven patients with 29 sites of suspected bone infection underwent immunoscintigraphy with 750 MBq 99mTc-labelled AGA. Planar scans were acquired immediately, 4 h and 24 h after injection, and combined SPET/CT was performed using a dual-head multifunctional gamma camera equipped with a low-power X-ray system. Accumulation of AGA in inflammatory lesions was quantitated, comparing uptake at 4 and 24 h after injection. The validation was based on culture data derived from surgical or biopsy samples (20 lesions in 18 patients) or clinical follow-up without further therapy for more than 6 months (nine lesions). On a lesion-by-lesion basis 19 true positive, one false positive and nine true negative findings were obtained. SPET/CT correctly identified the location of all positive foci in the appendicular skeleton and that of a cold lesion in the axial skeleton. It also enabled differentiation between soft tissue infection, septic arthritis and osteomyelitis, as well as between cortical, corticomedullary and subperiosteal foci. Sensitivity was identical for SPET and SPET/CT (100%), whereas specificity was improved from 78% to 89% by the use of SPET/CT. Combined SPET/CT improves the accuracy of immunoscintigraphy by allowing correct differentiation between soft tissue infection and bone involvement. This technique may gain clinical relevance in the selection of patients for surgical therapy.

Adult↗
PubMed2003

Benefit of anatomical-functional image fusion in the diagnostic work-up of neuroendocrine neoplasms.

The aim of this prospective study was to evaluate anatomical-functional image fusion using the new technology of combined transmission and emission tomography (SPET/CT) in patients with neuroendocrine tumours (NET). Fifty-four patients with known or suspected NET prospectively underwent both tumour scintigraphy with (111)In-octreotide (n=43) or (123)I-MIBG (n=11) and contrast-enhanced high-end spiral CT. Scintigraphy was performed using a gamma camera (Millennium VG & Hawkeye, GE) with an integrated X-ray tube for combined transmission and emission tomography. SPET and high-end CT were interpreted blinded with regard to localisation and classification of lesions. Analysis of fused images (SPET/CT) was done on a lesion-by-lesion basis, followed by re-evaluation of SPET and high-end CT by consensus. The standard of reference for confirming the presence or absence of malignancy was either histopathology or clinical and imaging follow-up data. A total of 120 lesions were identified by CT and/or scintigraphy. This group included four patients with negative SPET but eight liver lesions on CT that were proven to be metastases. We excluded from the analysis two patients with no evidence of tumour on either modality, two lesions that lacked comparison with the standard of reference and two patients, each with two lesions, who were lost to follow-up. In 56 of the 114 evaluated lesions (49%), the results of SPET and CT were concordant; all lesions were interpreted as malignant. In 58 of 114 lesions (51%), consensus reading of fused images changed the image interpretation of 39 CT scans and 19 SPET studies: 31 lesions previously interpreted as equivocal (n=10) or benign (n=21) were re-classified as malignant and 27 lesions previously interpreted as equivocal (n=19) or malignant (n=8) were re-evaluated as benign. The highest accuracy (99%) in classifying NET lesions was achieved by combined analysis of SPET/CT ("hawkeye") and high-end CT. The specificity of SPET/CT was significantly higher than that of CT alone (P=0.0026) and slightly higher than that of SPET alone, but the accuracy of SPET/CT was inferior to that of side-by-side analysis of SPET and high-end CT (P=0.013) or visual correlation of SPET/CT and high-end CT (P<0.0001). Therapy was changed in 14 of 50 patients (28%) owing to the results of image fusion: in five patients tumour could be excluded, three patients were spared unnecessary surgery because of additional lesions indicating systemic tumour spread, in four patients the surgical approach was changed owing to precise tumour localisation and minimising of the surgical field, and in two patients medical and radiopeptide therapy was changed. Anatomical-functional image fusion allows for improved localisation and characterisation of NET with resultant alteration of the treatment approach in a substantial proportion of patients.

Adult↗
PubMed2003

Lipid content in the musculature of the lower leg assessed by fat selective MRI: intra- and interindividual differences and correlation with anthropometric and metabolic data.

PURPOSE: To assess the muscular lipid content (LC) in different muscle groups of the lower leg by a magnetic resonance imaging technique working with chemical shift selective excitation, and comparison with anthropometric and metabolic data. MATERIALS AND METHODS: Examinations were performed in 67 volunteers (54 male/13 female, age 29 +/- seven years) on a 1.5 T whole body imager, applying a highly selective spectral-spatial technique for fat selective MRI. LC was measured in six calf muscles and correlated with body mass index (BMI), percent body fat (PFAT), and insulin sensitivity (IS) of the subjects. RESULTS: Mean muscular LC of all subjects was between 2.0% (Tibialis posterior [TP]) and 3.8% (Peroneus muscles) with female subjects showing a significantly higher LC in all muscle groups (P < 0.05 each). LCs correlated moderately with BMI (R between 0.39 [TP] and 0.53 [GM]) and with PFAT (R between 0.38 [TP] and 0.62 [GM]). Insulin-resistant subjects showed slightly but not significantly increased LC compared to insulin-sensitive subjects in BMI-matched subgroups. CONCLUSION: The fat-selective MRI technique allows a reliable non-invasive measure of muscular lipids - even in muscle groups with inherent low LC - within a relatively short measurement time of about three minutes. The presented data reveal interesting interrelationships between LC and anthropometric and metabolic data, and therefore provide new insight into muscular fat metabolism.

Adult↗