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G Adam

Publications and source records attributed to G Adam.

At least 37 records · Page 2Linked to original sources
PubMed2005

[MRI of pulmonary arteries in follow-up after arterial-switch-operation (ASO) for transposition of great arteries (d-TGA)].

PURPOSE: To determine the value of MRI in postoperative evaluation of patients with arterial-switch-operation (ASO) for d-TGA. MATERIAL AND METHODS: 14 consecutive patients with d-TGA and ASO were examined with MRI in addition to ultrasound because the acoustic window in echocardiography was insufficient. Nine patients had a pulmonary-artery-bifurcation anterior to the aortic root (group 1), and five (group 2) laterally (two of them left, three of them right). MRI was performed in six patients as contrast-enhanced MR-angiography, in 8 patients as native examination. Diameters of pulmonary arteries were measured in two perpendicular views at the origin and in two further locations each with a distance of one cm. RESULTS: One patient showed a supravalvular pulmonary artery stenosis with subsequent pulmonary artery aneurysm, which had not been detected in echocardiography. This patient showed only indirect signs of pulmonary artery stenosis in echocardiography. Compared to group 1, pulmonary arteries in group 2 generally had greater diameters. Those pulmonary arteries in Group 2 which cross the mediastinum underneath the aortic arch had lower diameters compared to the pulmonary artery positioned on the other side. In group 1, the left-sided pulmonary artery had lower diameters than the right-sided pulmonary arteries. It seems remarkable that the narrowing of pulmonary arteries is associated with a flattening of the transversal vessel diameter. CONCLUSION: Narrowing of pulmonary arteries after ASO is associated with oval vessel diameters. Therefore, multiplanar diagnostic methods are necessary. MRI meets this prerequisite and is therefore advantageous to echocardiography in follow-up examinations at patients with ASO for d-TGA. Special attention should be focused on the main pulmonary artery, on the left pulmonary artery in patients with preaortic pulmonary artery bifurcation as well as on the pulmonary artery which crosses the mediastinum in patients with laterally placed pulmonary artery bifurcation. Angiography should only be performed when intervention is planned.

Adolescent↗
PubMed2005

Diffusion-weighted echo-planar MRI: a valuable tool for differentiating primary parotid gland tumors?

PURPOSE: To investigate the feasibility of using diffusion-weighted (DW) echo-planar imaging (EPI) for differentiating primary parotid gland tumors. MATERIAL AND METHODS: Fifty consecutive patients with a suspected primary tumor of the parotid gland were examined with a DW EPI sequence (TR 1,500 msec, TE 77 msec, field of view 250 x 250 mm, pixel size 2.10 x 1.95 mm, section thickness 5 mm). The b factors used were 0, 500, and 1,000 sec/mm (2). Apparent diffusion coefficient (ADC) maps were digitally transferred to MRIcro (Chris Rorden, University of Nottingham, Great Britain) and evaluated with a manually placed irregular region of interest (ROI) containing the entire tumor. Additionally, the contralateral, non affected parotid gland was measured and a circular ROI containing 100 - 200 pixels was placed in the cerebrospinal fluid (CSF) next to the spinal cord in every patient. For comparison of the results, the two-tailed Student's t test was used, based on the median ADC values for each patient, and a p-value <.05 was determined to indicate statistical significance. RESULTS: In 45 patients, a primary neoplasm of the parotid gland could be histologically verified. For the non-affected parotid glands of all 45 evaluated patients, the mean ADC value was 1.14 x 10 ( - 3) mm (2)/sec +/- 0.12 x 10 ( - 3) mm (2)/sec (mean +/- standard deviation). Seven different entities of parotid gland tumors were histologically discriminated. Pleomorphic adenomas (2.14 x 10 ( - 3) mm (2)/sec +/- 0.11 x 10 ( - 3) mm (2)/sec), Warthin tumors (0.85 x 10 ( - 3) mm (2)/sec +/- 0.1 x 10 ( - 3) mm (2)/sec), and mucoepidermoid carcinomas (1.04 x 10 ( - 3) mm (2)/sec +/- 0.3 x 10 ( - 3) mm (2)/sec) showed statistically significant different ADC values in comparison to all other evaluated tumors (p .001), and also among each other (p <.001). Additionally, ADC values presented by lipomas were statistically significant compared to all other entities (p <.001 to .015). Among all other [corrected] primary malignant parotid gland tumors, no statistically significant ADC values could be observed (p .18 to 1). CONCLUSION: Diffusion-weighted echo-planar MRI seems to be a valuable tool for differentiating benign from malignant primary parotid gland tumors.

Adolescent↗
PubMed2005

[Labeling of mesenchymal stem cells with different superparamagnetic particles of iron oxide and detectability with MRI at 3T].

PURPOSE: In vitro evaluation of labeling efficiency of human mesenchymal stem cells (hMSCs) with different types of superparamagnetic iron oxide nanoparticles as well as detection and quantification by MRI at 3T. MATERIAL AND METHODS: hMSCs were incubated for 24 hours with 5 ultrasmall superparamagnetic particles of iron oxide (USPIO) contrast agents (1 : 30 - 1 : 30,000) of different size, coating and core compound: Endorem, Resovist, citric acid coated magnetite cores of 3 nm (CMF3), 7 nm (CMF7) and 12 nm (CoF, core: cobalt ferrite). Iron uptake, intracellular retention, detection and quantification were evaluated with MRI up to 5 weeks after incubation by cytological analysis (Prussian blue), atomic absorption spectrometry and MR relaxometry measurements. RESULTS: An effective labeling of hMSCs was achieved using Resovist, CMF3 and CMF7 with mean iron concentrations of 5.1/1.8, 1.9/1.4 and 1.5/1.0 pg/cell (dilutions 1:30 [933, 2100, 2800 microg Fe/ml]/1 : 300 [93, 210, 280 microg Fe/ml]) compared with 0.58/0.34 and 0.43/0.30 pg/cell (Endorem, CoF, dilution 1 : 30 [400, 4200 microg Fe/ml]/1 : 300 [40, 420 microg Fe/ml] unlabelled control cells: 0.01 pg/cell). Particle uptake correlated with the concentration of USPIO in the incubation medium. Detection of 5 x 10 (4) labelled cells/ml with MRI was possible up to 5 weeks after incubation (Resovist, CMF7 and CMF3). MR relaxometry measurements showed a strong correlation between cellular iron load and R2* (1/T2*), r > 0.78. No changes in cell viability or toxic effects were found. CONCLUSION: Efficiency of labeling hMSCs with USPIOs depends on coating, size and core compound of used particles. Carboxydextran-coated, clinically approved SPIO (Resovist, 50 nm) or ultrasmall citrate-coated particles (< 10 nm) result in an improved cellular uptake. In principle, the long intracellular retention of particles offers the possibility of cell tracking and migration monitoring in MRI.

Cells, Cultured↗
PubMed2005

[The ECG-gated 4-row multidetector CT of the heart in preoperative imaging minimal invasive coronary artery bypass grafting].

PURPOSE: Minimal invasive direct coronary artery bypass grafting (MIDCAB) or off-pump coronary artery bypass grafting (OPCAB) on the beating heart with full or mini-sternotomy are becoming more common in coronary bypass surgery of the left anterior descending (LAD). In the decision, which surgical approach (MIDCAB, OPCAB or conventional surgery with cardiopulmonary bypass) will be best used, knowledge of the anatomical field is of major importance. The aim of the study was to evaluate retrospective ECG-gated 4-row multidetector CT (MDCT) in patients planned for MIDCAB as additional imaging to coronary angiography. MATERIAL AND METHODS: The study included 25 consecutive patients. MSCT was performed as unenhanced (collimation 4 x 2.5 mm) and contrast-enhanced examination (140-170 ml, 300 mg Iodine/ml, collimation 4 x 1 mm). The evaluation included presence of LAD calcifications, distance of LAD and left internal mammarian artery (LIMA), course of LAD and LIMA, the presence or absence of bridging through myocardium or epicardial fat and the presence of pleural fibrosis. The MDCT results were correlated with intra-operative findings. RESULTS: All MDCTs could be assessed with reference to the demands. In 20/25 operations, MDCT had direct influence as to the selection of the surgical approach (11 MIDCAB, 7 OPCAB with mini-sternotomy and 5 with full sternotomy, 2 conventional surgeries). The distance of LAD and LIMA varied from 0.9 to 4.5 cm in MDCT. As to calcifications, 3/25 correlated patients had calcifications and 10 patients had no calcifications in the middle LAD. Seven patients had intraoperative fibrosis of the vessel wall without calcification of the middle LAD, which could not be detected with MDCT. Another 5 patients had single calcified plaques in the middle LAD, 4 of these had a fibrosis of the vessel and 1 had a normal vessel at surgery. In these cases, the anastomosis was done between the calcified plaques. No myocardial bridging was detected by MDCT and at surgery. Bridging of epicardial fat was shown by MDCT and at surgery in 9/25 patients and was excluded in 15 patients. In 1 patient, the LAD seemed to run superficially in MDCT, but was covered with fat as seen during surgery. The course of the LIMA was inconspicuous in all cases, no pleural fibrosis was found. CONCLUSIONS: The 4-row MDCT has proven to be adequate in addition to coronary angiography for preoperative evaluation in patients scheduled for MIDCAB and provides the surgeon with relevant information for the selection of the operative approach.

Aged↗
PubMed2005

[Clinical relevance of multislice CT of the spine after osteosynthesis].

PURPOSE: To examine the clinical relevance of multislice CT (MSCT) scans in postoperative checks of the spine after osteosynthesis. MATERIAL AND METHODS: The results of x-rays (apical lateral) in 30 patients having spinal surgery involving osteosynthesis (5 x metastasis, 20 x fractures, 3 x spondylolisthesis, 2 x scoliosis) were correlated to those of MSCT (140 kV, 200 mAs, collimation 4 x 1 mm, pitch 0.75; VolumeZoom, Siemens, Erlangen, Germany) with multiplanar reconstruction. Two radiologists independently checked the conventional x-ray and multislice CT scans for anatomical positioning, damage of osteosynthetic material, and intraspinal dislocation of bone fragments. RESULTS: By correlating conventional spinal x-rays with MSCT, additional diagnostic information was gained. In 9 of 30 patients MSCT revealed the extraosseal location of a screw tip (x-ray, 5/30), in 8/30 patients a narrowing of the spinal canal by osteosynthetic material was detected in MSCT (x-ray, 4/30), in 2/30 patients osteal fragments were detected in the vertebral canal by MSCT (x-ray, 0/30). In MSCT and in conventional x-ray a fracture of the osteosynthesis was correctly diagnosed in 3 patients. One patient underwent corrective surgery for dislocated osteosynthetic material, which was solely diagnosed with MSCT. CONCLUSION: Due to the high degree of additional diagnostic information MSCT seems to be the method of choice for postoperative spinal surgery involving osteosynthesis.

Adolescent↗
PubMed2005

[Diagnostic mammography and sonography: concordance of the breast imaging reporting assessments and final clinical outcome].

PURPOSE: The purpose of the study was to assess the final clinical outcome of BI-RADS Categories for diagnostic mammography and sonography. MATERIAL AND METHODS: We analysed 632 mammography and sonography examinations from women with diagnostic indications (age: 23 - 100, mean 58) performed during 2001 and 2003. All patients received mammography and sonography examinations at different outside facilities and all patients received an additional sonography examination at the university radiology department and if necessary supplemental mammographic views. Final clinical outcome (Histology: 554; follow-up: 78) was ascertained in each case and concordance of BI-RADS-categories for mammography and sonography and final diagnosis were analysed. RESULTS: Final diagnosis yielded 230 benign lesions (36 %) and 402 cancers (64 %). Concordance of BI-RADS Assessment and final outcome was documented in 542 cases (86 %). There were 11 correct category 1 and 2 assessments (2 %). 142 lesions were classified with BI-RADS 3 (22 %) with 5 false negative ratings. There were 264 category 4 lesions (42 %) with a PPV for a malignant lesion of 71 % (187/264) and finally 215 BI-RADS 5 lesions with a PPV of 98 % (210/215). Overall sensitivity of mammography was 92 % with specificity of 75 % and for sonography 86 % and 76 %. Mammography had a significantly higher detection rate for malignant lesions than sonography. The highest correlation between BI-RADS category and final outcome was documented for the diagnostic combination of mammography and sonography with a kappa-value of 0.817 (p < 0.001), followed by mammography (kappa: 0.684) and sonography (kappa: 0.631). The overall correlation was 0.681 (p < 0.001). CONCLUSION: BI-RADS assessments of diagnostic mammography and sonography yields in a high cancer detection rate with a justifiable part of false positive ratings.

Adult↗
PubMed2005

[Orthodontic brackets in high field MR imaging: experimental evaluation of magnetic field interactions at 3.0 Tesla].

PURPOSE: To evaluate static magnetic field interactions for 32 commonly used orthodontic brackets in a 3.0 T magnetic resonance imaging (MRI) system. MATERIALS AND METHODS: 32 orthodontic brackets consisting of a steel alloy (n = 27), a cobalt-chromium alloy (n = 2), ceramic (n = 1), ceramic with a steel slot (n = 1), and titanium (n = 1) from 13 different manufacturers were tested for magnetic field interactions in a static magnetic field at 3.0 T (Gyroscan Intera 3.0 T, Philips Medical Systems, Best, Netherlands). The magnetic deflection force F (z) [mN] was evaluated by determining the deflection angle beta [ degrees ] using the established deflection angle test according to the ASTM guidelines. The magnetic-field-induced rotational force F (rot) or torque was qualitatively determined using a 5-point grading scale (0: no torque; + 4: very strong torque). RESULTS: In 18 of the 32 brackets, the deflection angle beta was found to be > 45 degrees and the translational force exceeded the gravitational force F (G) on the particular bracket (F (z): 1.2 - 45.7 mN). The translational force F (z) was found to be up to 68.5 times greater than the gravitational force F (G) (F (z)/F (G): 1.4 - 68.5). The rotational force F (rot) was correspondingly high (+ 3/+ 4) for those brackets. For the remaining 14 objects, the deflection angles were < 45 degrees and the torque measurements ranged from 0 to + 2. The static magnetic field did not affect the titanium bracket and the ceramic bracket. No measurable translational and rotational forces were found. CONCLUSION: Of the 32 brackets investigated for magnetic field interactions at 3.0 T, 18 (56.25 %) were unsafe in the MR environment according to the ASTM guidelines. However, the forces measured were minimal compared to the forces generally necessary for dislodging these bonded orthodontic brackets from tooth surfaces. The implications of these results for orthodontic patients undergoing MR examinations at 3 Tesla are discussed.

Humans↗
PubMed2004

Pelargonium necrotic spot virus: a new member of the genus Tombusvirus.

A virus isolate from Pelargonium spp., provisionally designated UPEV (unknown pelargonium virus), had isometric particles 31-33 nm in diameter, with a granular surface structure similar to that of viruses in three genera of family Tombusviridae. Immunoelectron microscopy proved that UPEV was serologically distinct from all examined morphologically similar members of the family Tombusviridae. The induced cytopathology was characterized by large cytoplasmic virion aggregates and the formation of multivesicular bodies derived from mitochondria. Analysis of the complete ssRNA genome sequence revealed four open reading frames (ORFs) arranged like those of viruses in the genera Tombusvirus and Aureusvirus. Sequence comparisons indicated that three of the four ORFs had a high identity (52-97% identical amino acids) with the respective ORFs of tombusvirus species, especially with Carnation Italian ringspot virus, but not with those of viruses in other genera in Tombusviridae. On the contrary, UPEV coat protein had a low indentity (36-53% identical amino acids) with that of the aureusvirus Pothos latent virus. The data suggested that UPEV originated in a recombination event between a tombus- and an aureusvirus. According to its original host and symptom expression we proposed the new virus be named Pelargonium necrotic spot virus (PeNSV) and classified it as a distinct and new species in the genus Tombusvirus.

Capsid Proteins↗
PubMed2004

Anatomic variations of the hepatic arteries in 604 selective celiac and superior mesenteric angiographies.

In modern surgical and transplantation procedures the recognition of anatomic vascular abnormalities of the hepatic arteries is of greater importance than ever. The purpose of this study was to evaluate and classify these variations with respect to their impact on visceral surgery. A total of 604 selective celiac and superior mesenteric angiographies performed on patients with known or suspected liver cirrhosis or hepatic or pancreatic malignancies and on donors of partial liver grafts were analyzed retrospectively. The vascular anatomy of the liver was classified according to different established systems and with particular attention to rare variations. Hepatic arterial anatomy as considered normal in textbook descriptions was found in 79.1%, an aberrant or accessory left hepatic artery (LHA) arising from the left gastric artery in 3.0% and an aberrant or accessory right hepatic artery (RHA) branching off the superior mesenteric artery in 11.9% of the cases. In 1.4% of the cases there was a combination of anomalies of both the LHA and RHA. Variants of the celiac trunk, double hepatic arteries branching at the celiac trunk or hepatic arteries arising directly from the aorta, occurred in 4.1% of the cases. Further atypical branches of the LHA and RHA were found in 0.5% of the cases. Since the incidence and pattern of different types of hepatic arterial anatomy can require specialized preoperative diagnostic as well as intraoperative strategies, knowledge of these abnormalities and their frequency is of major importance for the surgeon as well as the radiologist.

Angiography↗
PubMed2004

[Simple bone cysts of the calcaneus. Differential diagnosis and therapy].

Fifty-two calcaneal simple bone cysts from our clinic were evaluated. The lesions had a pathognomonic radiologic appearance and diagnosis was histologically confirmed in all operatively treated cases. Four cases presented with pathological fractures, three of which were treated by open reduction internal fixation and bone grafting, while one was treated nonoperatively. In addition, six patients with large cysts without apparent fracture but spontaneous pain were treated by curettage and subsequent autogenous bone grafting or calcium phosphate cement filling, and there were no recurrences. The majority of cysts (42 of 52) were however asymptomatic and thus followed up nonoperatively. This review reports on one of the largest series of cysts in this location. The results indicate that nonoperative management is justified in most asymptomatic cases. However, the potential risk of fracture as indicated by four fractured calcaneal cysts in this series suggests that large cysts should be clinically monitored and that operative intervention is useful in all symptomatic cases to prevent pathologic fractures. In the latter cases, curettage and bone grafting as well as the use of bone substitute material yielded uniformly good results.

Adolescent↗
PubMed2004

[Radiological diagnostics of cervical rheumatoid arthritis].

Rheumatoid arthritis leads to characteristic findings at the synovial joints, the intervertebral discs and the processes of the cervical spine. Isolated findings are not specific for rheumatoid arthritis. In fact, due to common underlying pathophysiologic changes they also develop in other inflammatory diseases affecting the cervical spine. Therefore, each radiological examination is to be understood and used as a piece in the diagnostic puzzle. Only in conjunction with clinical information does it add to a conclusive diagnosis. Nevertheless certain patterns of findings help in narrowing the list of differential diagnosis. Besides their role in initial diagnosis, radiological examinations are crucial tools in the peri- and post-operative work-up and in the detection of typical complications of rheumatoid arthritis with cervical manifestations, i. e. various instabilities and their consequences, as those have an impact on the therapeutic approach and prognosis.

Arthritis, Rheumatoid↗
PubMed2004

[Imaging-based anatomy of the neck -- multi-slice CT and MRI].

Purpose of this article is to provide accomplishments of the anatomy in the evaluation of pathologic findings is not a mandatory knowledge of every single anatomical structure, but rather a correct attribution of pathology to a single space of the neck. Only with an exact assignment to these spaces the differential diagnoses can be limited to a reasonable quantity to provide support for the referring physician in the ongoing treatment, especially for the planning of the various existing neck dissections. There are multifaceted descriptions of the anatomy of the head and neck region regarding an axial scanning with CT and MRI. Because of their intricacy it is difficult to use these classifications in a daily routine setting. Classifications with nearly as many spaces as anatomical structures provide no adequate support. Based on the various spaces of the head and neck region and additionally the imaging-based lymph node classification the aim of this work is to provide reasonable support in the daily clinical routine regarding the current literature and our own experience.

Diagnosis, Differential↗
PubMed2004

[Evaluation of experimental cartilage lesions with ultrahigh-resolution multi-slice-CT in comparison to histology].

PURPOSE: Histologic validation of ultrahigh-resolution multi-slice (MS)-CT for the evaluation of focal, experimental cartilage lesions with special regard to the subchondral bone. Testing of micro-CT ( micro CT) as alternative reference standard. METHODS: 32 experimental cartilage lesions in bovine patellae were imaged surrounded by air (MS-CT-air) and immersed in a contrast material solution (MS-CT-CM) with MS-CT (collimation 2 x 0,5 mm). After the micro CT (8 micro m-voxelsite) examination in three specimen and histologic work-up of 29 specimen two radiologist graded the defects on MS-CT images in consensus (subchondral bone involvement yes or no) and results were compared to the results of histomorphometry and micro CT. RESULTS: The MS-CT-air and -CM had an accuracy of 94 % (30/32) and 88 % (28/32), respectively. MS-CT-air led to one false-positive (remaining cartilage: = 0,1 mm) and false-negative result, each. MS-CT-CM showed false-positive results if the remaining cartilage was < 0,3 mm thick (n = 4), i. e. showed subchondral bone involvement. Contrast-to-noise ratio was significantly higher in MS-CT-air compared to MS-CT-CM. micro CT yielded a clear depiction of cartilage defect depth in the three cases. CONCLUSION: MS-CT-air has a high accuracy in the depiction of focal cartilage defects. MS-CT-CM has a tendency to overestimate cartilage defect depth. micro CT could potentially serve as alternative reference standard to histology.

Animals↗
PubMed2004

[Diagnostic imaging in polytrauma: comparison of radiation exposure from whole-body MSCT and conventional radiography with organ-specific CT].

PURPOSE: To compare the radiation dose of whole-body multislice CT (MSCT) and conventional radiography with organ-specific CT in polytrauma. MATERIALS AND METHODS: The whole-body MSCT encompassing brain, neck and midface, chest, abdomen and pelvis was performed on a Somatom Volume Zoom (Siemens). Conventional radiography consisted of chest and cervical, thoracic and lumbar spine in two views as well as pelvis (Polymat, Siemens). Three combinations of organ specific CT were chosen: CT examination of (1) head and cervical spine, (2) head, cervical spine and chest, (3) head, cervical spine and abdomen. The effective doses of whole-body MSCT and conventional radiography with organ-specific CT were calculated. RESULTS: Effective doses were 20 mSv for whole-body MSCT, 2 mSv for conventional x-ray, and 5 mSv for combination (1), 8 mSv for combination (2) and (3) 16 mSv for combination (3) of the organ-specific CT. The ratio of radiation dose between whole-body MSCT and radiography was 10 : 1. This ratio was reduced to 3 : 1, 2 : 1 and 1 : 1 when a combination of radiography and CT was performed. CONCLUSIONS: Whole-body MSCT in polytrauma compared to conventional radiography with organ-specific CT induces a threefold increased dose in unfavorable situations and no increased dose in favorable situations. Nevertheless, routine use of whole-body MSCT should be critically evaluated and should be adapted to the clinical benefit.

Humans↗
PubMed2004

MR elastography of the prostate: initial in-vivo application.

PURPOSE: To analyze the initial assessment of the technical feasibility of in-vivo MR elastography (MRE) of the prostate gland in healthy volunteers. MATERIALS AND METHODS: Dynamic sinusoidal MR elastography was performed in 7 healthy volunteers in prone position. The mechanical wave was induced via an external oscillator attached to the pubic bone. A 1.5 Tesla MR system (Philips Medical Systems, Netherland) was used with 4 combined surface coils for signal reception. MRE data acquisition was performed with a motion-sensitive spin-echo MR sequence that was phase-locked to the mechanical oscillation. Subsequently, these images were used to reconstruct the local distribution of elasticity inside the prostate gland. The applied reconstruction algorithm was tested by means of phantom measurements. RESULTS: Sufficient penetration of the mechanical wave into the prostate gland was achieved in all volunteers, allowing the acquisition of utilizable image data sets. The reconstructed distribution of elasticity (shear-modulus) inside the healthy prostate gland correlated with the zonal anatomy of the gland. The elasticity of the central portion (2.2 +/- 0.3 kPa) appeared to be lower than the peripheral prostatic portion (3.3 +/- 0.5 kPa). CONCLUSION: In-vivo MRE of the prostate gland is technically feasible. The proposed experimental set-up allows the efficient insertion of the mechanical wave into the prostate gland and provides a successful MR data acquisition.

Adult↗
PubMed2004

[Image quality of thin- and thick-slice MSCT reconstructions in low-contrast objects (liver lesions) with equal doses].

PURPOSE: To evaluate the image quality of thin-section MSCT examinations of low-contrast objects such as liver lesions, and to find out whether a thin slice technique requires an increase in radiation dose. MATERIALS AND METHODS: MSCT examinations of the liver were performed in the portal venous phase on a Volume Zoom Scanner (Siemens, Erlangen) with a collimation of 4 x 2.5 mm, 120 kV, 125 mAs and table speed of 12.5 mm. Forty small hypodense liver lesions with a mean size of 3 mm (1 to 8 mm) were reconstructed using a slice thickness of 3, 5, 7, and 10 mm. All lesions were evaluated for each slice thickness by 3 independent radiologists using a 5-point scale (excellent to poor) for the following 7 criteria: contrast, demarcation and contour of the lesion, image noise and quality, demarcation of liver veins and liver contour. The mean values of the reviewers' scores were calculated. The correlation of the three observers in the evaluation of the criteria was determined using the Kendall's Tau coefficient. RESULTS: The 3-mm thin sections were excellent in the evaluation of lesion detection, lesion contrast and lesion contour with a mean score of 1.4 compared to 4.1 for 10-mm sections. Concerning the criteria image quality and liver contour, thin sections achieved the best results in our series. Image noise was pronounced in thin sections but did not affect negatively the image analysis. Interrater agreement was 0.53 for the criterium image noise. CONCLUSION: Thin sections in MSCT examinations of low contrast objects such as liver lesions do not require an increase in radiation dose because the increase in image noise is compensated by improved lesion contrast.

Contrast Media↗
PubMed2004

Functional imaging of parotid glands: diffusion-weighted echo-planar MRI before and after stimulation.

PURPOSE: To investigate the feasibility of diffusion-weighted (DW) echo-planar imaging (EPI) for measuring different functional conditions of the parotid gland and to compare different measurement approaches. MATERIALS AND METHODS: Parotid glands of 27 healthy volunteers were examined with a DW EPI sequence (TR 1,500 msec, TE 77 msec, field-of-view 250 x 250 mm, pixel size 2.10 x 1.95 mm, section thickness 5 mm) before and after oral stimulation with commercially available lemon juice. The b factors used were 0, 500, and 1,000 sec/mm (2). Apparent diffusion coefficient (ADC) maps were digitally transferred to MRIcro (Chris Rorden, University of Nottingham, Great Britain) and evaluated with a manually placed circular region of interest (ROI) containing 100 - 200 pixel. Additional ROIs including the entire parotid gland were placed on either side. The results of both measurements were compared, using the Student's t test based on the median ADC values for each person. A two-tailed p-value of less than.05 was determined to indicate statistical significance. To compare both measurement approaches, the Pearson's correlation coefficient (r) was calculated. RESULTS: Diffusion-weighted echo-planar MR imaging successfully visualized the parotid glands of all volunteers. In a first step, the median ADC value per person was computed. Using ROIs of 100 - 200 pixels, the mean was calculated to be 1.08 x 10 (- 3) mm (2)/sec +/- 0.12 x 10 (- 3) mm (2)/sec for both parotid glands prior to stimulation. After stimulation, the mean ADC was measured at 1.15 x 10 (- 3) mm (2)/sec +/- 0.11 x 10 (- 3) mm (2)/sec for both parotid glands. Evaluating the entire parotid gland, the ADC was 1.12 x 10 (- 3) mm (2)/sec +/- 0.08 x 10 (- 3) mm (2)/sec prior to stimulation, whereas the ADC increased to 1.18 x 10 (- 3) mm (2)/sec +/- 0.09 x 10 (- 3) mm (2)/sec after stimulation with lemon juice. For both types of measurements, the increase in ADC after stimulation proved to be significant (p < 0.001). High correlations between both measurement types were found (r >.83). CONCLUSION: Diffusion-weighted echo-planar MR imaging allows non-invasive quantification of functional changes in the parotid glands.

Adult↗