[Image quality of thickened slabs in multislice CT chest examinations: postprocessing vs. direct reconstruction]. / Bildqualität aufaddierter Schichten bei MSCT-Untersuchungen des Thorax: Bildnachverarbeitung versus Direktrekonstruktion.

PURPOSE: Postprocessing offers the possibility of real-time creation of thickened slabs from a set of thin slices. This allows the interactive change from thick to thin slices for better evaluation of unclear lesions. As a result the clinical workflow of MSCT evaluation can be improved. However, to be able to apply this postprocessing software in the clinical routine, degradations in the image quality (compared to standard original reconstructed images) have to be avoided. The purpose of this study was to compare the image quality of thickened slabs from MSCT chest examinations that have either been directly reconstructed from the raw data or have been retrospectively generated via postprocessing. MATERIALS AND METHODS: Chest MSCT examinations of 20 patients (mean age: 56 years) were performed on a 16-slice MSCT scanner (Mx8000IDT16, Philips, Best, Netherlands) using the following scan parameters: 120 kV, 94 effective mAs, 16 x 1.5 mm collimation, 512 x 512 matrix, field of view 371 x 371 mm, CTDIvol = 6.3 mGy, DLP = 210 mGyxcm). Slices with a thickness of 3 and 5 mm were generated for each examination both directly from the raw data and via postprocessing. Corresponding images from postprocessing and direct reconstruction (lung/soft tissue window) were evaluated by two radiologists with respect to 5 criteria on the basis of a five-point scale: organ structure, contour of small objects, contrast, image noise and artifacts. Differences between both data sets regarding image quality were assessed for each of the 5 criteria using a Wilcoxon test with Bonferroni correction. In addition, image noise was analyzed quantitatively in a region of interest in the aorta. RESULTS: For the lung and soft tissue window, both reviewers and all criteria, no differences in image quality were detected between the thickened slices obtained via direct reconstruction and the postprocessing method. In 96 % and 95 % of the cases images of the two reconstruction methods were graded identically for 3 mm and 5 mm slices. In the remaining 4 % and 5 %, the evaluations differed only by one point on the five-point scale. The median grade of the first reviewer was 1 and that of the second reviewer was 2. There were no differences in the quantitative analysis of image noise between both methods. CONCLUSION: The interactive creation of thickened slices is an effective tool for the evaluation of MSCT examinations. For the defined scan parameters in this study there were no differences in image quality between postprocessing methods (e. g. slab viewer) and direct image reconstruction.

[Calcium scoring and coronary angiography performed with multislice spiral CT -- clinical experience]. / Koronarkalkquantifizierung und Koronarangiographie mittels Mehrzeilendetektorspiral-CT -- Klinische Erfahrungen.

PURPOSE: To report our clinical experience in calcium scoring and coronary angiography with multislice computer tomography (MSCT). MATERIAL AND METHODS: Cardiac four-row MSCT (Siemens, Volume Zoom, Erlangen, Germany) was performed in 60 patients, comprising 45 patients without known coronary vessel disease (CVD) and falling in an intermediate risk (group I) by calcium scoring, and 15 patients with multivessel disease by the combination of calcium scoring and MSCT coronary angiography (group II). Group I underwent analysis of risk factors as well as patient management in the form of risk profile modulation, indication for invasive selective coronary angiography (SCA) and supplemental myocardial diagnostic evaluation (e. g., SPECT). Agatston and volume scores (Virtuoso, Siemens, Erlangen, Germany) were calculated for calcium scoring. Group II had the calcium scoring and diagnostic accuracy of MSCT in detecting coronary artery stenosis evaluated according to established American Heart Association (AHA) criteria. SCA was used as gold standard. RESULTS: In group I, calcium scoring was positive in 27/45 (60 %) patients, with 14/27 (52 %) consecutively referred to SCA and 2/27 (7 %) to SPECT. SCA revealed significant coronary stenosis (> 60 %) in 5/27 (19 %) patients and SPECT detected myocardial ischemia in 0/2 patients. Patients with obstructive coronary vessel disease showed a significantly increased calcium score of > 300 together with a high risk profile. Patients with negative calcium score showed significantly less risk factors (p < 0.05). The use of calcium scoring in therapeutic procedures in the form of increased modulation of risk factors was documented in 21/45 (47 %) patients. In group II, sensitivity, specificity and diagnostic accuracy for the detection of high grade coronary artery stenosis were 64 %, 99 % and 96 %, and the Agatston and Volume scores were 333 +/- 123 and 334 +/- 136, respectively. CONCLUSION: MSCT can be applied as risk profile module for coronary screening of patients with intermediate risk. As non-invasive alternative for the evaluation of coronary vessel disease, it can be useful in some cases by providing additional information.

[Dose optimization for multislice computed tomography protocols of the midface]. / Dosisoptimierung der Mehrzeilen-Spiral-CT (MSCT) des Mittelgesichts.

PURPOSE: To optimize multislice computed tomography (MSCT) protocols of the midface for dose reduction and adequate image quality. MATERIALS AND METHODS: MSCT (Somatom Volume Zoom, Siemens) of the midface was performed on 3 cadavers within 24 hours of death with successive reduction of the tube current, applying 150, 100, 70 and 30 mAs at 120 kV as well as 40 and 21 mAs at 80 kV. At 120 kV, a pitch of 0.875 and collimation of 4x1 mm were used, and at 80 kV, a pitch of 0.7 and collimation of 2x0.5 mm. Images were reconstructed in transverse and coronal orientation. Qualitative image analysis was separately performed by two radiologists using a five-point scale (1 = excellent; 5 = poor) applying the following parameters: image quality, demarcation and sharpness of lamellar bone, overall image quality, and image noise (1 = minor; 5 = strong). The effective body dose [mSv] and organ dose [mSv] of the ocular lens (using the dosimetry system "WINdose") were calculated, and the interobserver agreement (kappa coefficient) was determined. RESULTS: For the evaluation of the lamellar bone, adequate sharpness, demarcation and image quality was demonstrated at 120 kV/30 mAs, and for the overall image quality and noise, 120 kV/40 mAs was acceptable. With regard to image quality, the effective body dose could be reduced from 1.89 mSv to 0.34 mSv and the organ dose of the ocular lens from 27.2 mSv to 4.8 mSv. Interobserver agreement was moderate (kappa = 0.39). CONCLUSION: Adequate image quality was achieved for MSCT protocols of the midface with 30 mAs at 120 kV, resulting in a dose reduction of 70 % in comparison to standard protocols.

[Clinical relevance of multislice CT of the spine after osteosynthesis]. / Postoperative Kontrolle von osteosynthetischen Versorgungen der Wirbelsäule mit der Mehrzeilen-Spiral-CT.

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.

[Quality rating of MR-cholangiopancreatography with oral application of iron oxide particles]. / Wertigkeit der MR-Cholangiopankreatikographie nach Gabe eines oralen eisenhaltigen Kontrastmittels.

PURPOSE: To compare image quality in magnetic resonance cholangiopancreatography (MRCP) performed with and without oral application of Lösferron (ferrous gluconate, Lilly Pharma, Hamburg). MATERIALS AND METHODS: A prospective study compares MRCPs performed on 52 patients with a 1.5 T clinical whole body scanner using a standard body coil. After randomization, patients ingested either 0.5 l of Lösferron (n = 27, group 1) or no oral contrast agent (n = 25, group 2) prior to the examination. 7 RARE (40 to 20 degrees) sequences were obtained, followed by selected 3 mm HASTE (T 2 -weighted with fat suppression) sequences. After blinding, image quality was rated by two radiologists using a scale of 1 (not discernible) to 5 (very well discernible). The following sections of the biliary ductal system were evaluated: left and right hepatic duct, extrahepatic bile duct and intrapancreatic bile duct. The pancreatic duct was evaluated by its location: head, body and tail of the pancreas. A Wilcoxon-Mann-Whitney test was used to determine significant differences (p < 0.05) between sampled ductal segments. Correction for multiple testing was applied. RESULTS: The oral application of Lösferron was well tolerated by all patients, and all sequences could be acquired and evaluated in all 52 patients. For the different sections of the biliary system, the mean ratings with and without Lösferron were, respectively, 3.28 and 3.36 for the left hepatic duct, 3.26 and 3.33 for the right hepatic duct, 3.46 and 4.0 for the extrahepatic bile duct, and 2.8 and 3.48 for the intrapancreatic bile duct. The corresponding ratings for the pancreatic duct were 2.8 and 3.24 for the pancreatic head, 2.84 and 3.38 for the pancreatic body, and 2.68 and 3.22 for the pancreatic tail. The differences with and without contrast agent were not statistically significant. Interobserver variability was between 0.37 for the pancreatic duct in the tail of the pancreas and 0.66 for the right hepatic duct. CONCLUSION: Despite the trend toward a better rating of the image quality for all sections of the pancreaticobiliary ductal system with Lösferron, a significant difference was not found in any ductal section after correction for multiple testing. Thus, we believe that the ingestion of Lösferron is not absolutely required prior MRCP.

[Radiation exposure of the head, midface and pelvis in multi-slice CT (MSCT): comparison with single-slice CT (SSCT)]. / Strahlenexposition bei der Mehrschicht-Spiral-CT (MSCT) von Kopf, Mittelgesicht und Beckenskelett: Vergleich mit dem Einzeilen-Spiral-CT (SSCT).

PURPOSE: Comparison of the radiation exposure of the head, midface and pelvis in multi-slice CT (MSCT) and single-slice CT (SSCT) for manufacturer-implemented standard protocols. MATERIALS AND METHODS: An anthropomorphic Alderson-Rando phantom equipped with LiF-thermoluminescent dosimeters in the head, neck and pelvic region was examined with different MSCT and SSCT protocols, and the measured organ doses were compared. RESULTS: In comparison with the SSCT protocols, the MSCT protocols delivered about twice the organ dose to the head and pelvis and about eight times the organ dose to the midface. The comparison indicates that the parameters (slice collimation, mAs, pitch) used for the MSCT protocols deliver increased radiation doses. CONCLUSIONS: The current standard MSCT protocols generally lead to higher organ doses to the head, midface and pelvis than the SSCT protocols, raising the question whether using the MSCT protocols recommended by the manufacturer can be justified. The dose parameters should be optimized to achieve an acceptable balance of dose reduction and adequate image quality.

[Clinical relevance of computed tomography under emergency conditions--diagnostic accuracy, therapeutic consequences]. / Klinische Relevanz der Computertomographie unter Notdienstbedingungen--Diagnostische Treffsicherheit, therapeutische Konsequenzen.

PURPOSE: To evaluate the diagnostic accuracy and therapeutic consequences of computed tomography performed on an emergency basis in a primary care hospital. MATERIAL AND METHODS: In 418 patients, 463 computed tomographies (thorax, abdomen, pelvis, spine, aorta, neck and extremities) were performed with-in 12 months, providing 999 diagnoses. The computed tomography diagnoses were retrospectively evaluated and correlated to surgery and discharge diagnoses. Therapeutical consequences were analyzed and allocated to a time period < 36 h (urgent) and > or = 36 - 72 h (elective). Average age was 49 (1 - 94) years (41% female and 59% male). Discharge diagnosis was defined as gold standard, provided that it was supported by clinical, blood chemical, diagnostic and possible surgical data. RESULTS: In 176 of 999 diagnoses (18%), the diagnoses were classified as "non-correlatable". Of the 823 correlated diagnoses, 431 were true positive, 14 false positive, 66 false negative and 312 true negative. Sensitivity, specificity and diagnostic accuracy of computed tomography was 87, 96 and 90%. Computed tomography had therapeutic consequences (surgery, drainage, puncture, reposition, thrombolytic therapy, chemotherapy, bronchoscopy, endoscopy, percutaneous transluminal angioplasty, coiling etc.) in 57% and no direct therapeutic interventions in 43%. Computed tomography excluded the suspected diagnosis in 36% and resulted in a conservative therapeutic regiment in 7%. Surgery was performed on 134 of the 418 patients (32%) who underwent computed tomography, with the surgery urgent in 71 (17%) and elective in 63 (15%) of the 418 patients. CONCLUSION: The high diagnostic accuracy and consecutive therapeutic consequences of computed tomography in establishing a precise, timely and reproducible diagnosis confirm its important role as primary diagnostic method on an emergency basis.

Functional magnetic resonance imaging (fMRI) for fetal oxygenation during maternal hypoxia: initial results.

PURPOSE: To investigate the potential of fMRI to measure changes in fetal tissue oxygenation during acute maternal hypoxia in fetal lambs. MATERIAL AND METHODS: Two ewes carrying singleton fetuses (gestational age 125 and 131 days) underwent MR imaging under inhalation anesthesia. BOLD imaging of the fetal brain, liver and myocardium was performed during acute maternal hypoxia (oxygen replaced by N 2 O). Maternal oxygen saturation and heart rate were monitored by a pulse-oxymeter attached to the maternal tongue. RESULTS: Changes of fetal tissue oxygenation during maternal hypoxia were clearly visible with BOLD MRI. Signal intensity decreases were more distinct in liver and heart ( approximately 40 %) from control than in the fetal brain ( approximately 10 %). CONCLUSIONS: fMRI is a promising diagnostic tool to determine fetal tissue oxygenation and may open new opportunities in monitoring fetal well being in high risk pregnancies complicated by uteroplacentar insufficiency. Different signal changes in liver/heart and brain may reflect a centralization of the fetal blood flow.

[Multislice CT (MSCT) in the detection and classification of pelvic and acetabular fractures]. / Multislice CT (MSCT) in der Detektion und Klassifikation von Becken- und Azetabulumfrakturen.

PURPOSE: To assess the usefulness of MSCT in the detection and classification of pelvic and acetabular fractures. MATERIALS AND METHODS: Routine radiographs and MSCT of the pelvis with sagittal and coronal multiplanar reconstruction (MPR) were performed in 50 patients with clinically suspected pelvic or acetabular fractures. One trauma surgeon and a radiologist evaluated routine radiographs and CT images in terms of fracture detection, classification and visualization. The AO classification of fractures was used. RESULTS: MSCT excluded a suspected fracture in 15 patients. In the remaining 35 patients, 19 anterior pelvic ring fractures, 10 anterior and posterior pelvic ring fractures, 8 acetabular fractures and 4 sacral fractures were diagnosed. All MSCT diagnoses were made from the axial source images. In 7 (17 %) patients, MSCT detected additional fractures (2 acetabular and 5 posterior pelvic ring fractures) not seen on conventional radiographs. In 3 other patients, MSCT changed the fracture classification by delineating the full extent of the fracture. MPR visualized 7 acetabular and 4 sacral fractures better than the axial source images. CONCLUSIONS: MSCT of the pelvis is needed for correct fracture detection and classification and has therapeutic consequences.

[Diagnostic imaging in polytrauma: comparison of radiation exposure from whole-body MSCT and conventional radiography with organ-specific CT]. / Radiologische Bildgebung beim Polytrauma: Dosisvergleich von Ganzkörper-MSCT und konventionellem Röntgen mit organspezifischer 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.

[Percutaneous stereotactic biopsy of non-palpable breast lesions using the Advanced Breast Biopsy Instrumentation (ABBI) system: critical evaluation of indication strategies]. / Perkutane stereotaktische Biopsie nicht palpabler Mammaläsionen mit dem Advanced Breast Biopsy Instrumentation (ABBI) System: Kritische Evaluation der Indikationsstellung.

PURPOSE: To compare the indications for biopsy with and without the use of the Breast Imaging Reporting and Data System. MATERIAL AND METHODS: Biopsies using the ABBI were performed in 62 patients with 64 non-palpable evident mammographic lesions. The initial decision for biopsy was made by non-radiologists due to suspicious microcalcifications (n = 53) and masses (n = 11). The indication was retrospectively reassessed by adopting the BI-RADS classification by three radiologists in consensus. The positive predictive value (PPV) of both indication strategies was assessed and compared. RESULTS: Biopsies adopting ABBI were performed without major side-effects and were diagnostic. Carcinoma was present in 14 lesions: nine specimens were diagnosed as DCIS and five as invasive carcinomas. For the 50 benign lesions histology revealed mastopathies (26/50) and fibroadenomas (8/50) as the most frequent diagnosis. The positive predictive value (PPV) for the initial indication was 22%, whereas PPV for BI-RADS based indications (categories 4 and 5) was 31%. CONCLUSION: ABBI enables stereotactically-guided procedures that result in representative and diagnostic biopsies. Standardized criteria like BI-RADS improve the PPV and should be a mandatory part of mammographic evaluation. Radiologists should remain involved in the decision making.

[Image quality of thin- and thick-slice MSCT reconstructions in low-contrast objects (liver lesions) with equal doses]. / Dünn- und dickschichtige MSCT-Untersuchungen bei Niedrigkontrastobjekten (Leberläsionen): Vergleich der Bildqualität bei gleicher Dosis.

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.

[Multislice CT of the pelvis: dose reduction with regard to image quality]. / Mehrzeilen-Spiral CT (MSCT) des Beckenskelettes: Dosisoptimierung unter Berücksichtigung der Bildqualität.

PURPOSE: To optimize the examination protocols of multislice CT (MSCT) of the pelvis for dose reduction with regard to image quality. MATERIALS AND METHODS: MSCT of the pelvis was performed on 5 cadaver specimens with stepwise reduction of the tube current at 140 kV (250, 200, 150, 100, 75, 50, 35, 25 mAs) and 120 kV (50, 27 mAs). The remaining scan parameters like collimation (4 x 1 mm) and table speed of 4 mm per rotation remained unchanged. Axial sections and coronal reconstructions were used to evaluate cortex, trabecular structures, subjective image quality, image noise and detail detectability (pelvis and SI joint), with evaluation performed independently by four blinded experienced radiologists on a 5-point scale. Kappa coefficient, accuracy of the observers to sort the films with regard to dose reduction and mean scores of image evaluation were determined for statistical analysis. RESULTS: The deterioration of the image quality was most pronounced for all criteria between 75 mAs and 50 mAs at 140 kV. Good results with adequate image quality were obtained for detail detectability at 50 mAs and 140 kV (effective dose [E]: 3.3 mSv) and for the remaining four criteria at 75 mAs (E: 4.9 mSv). There was a moderate agreement between the four observers (kappa coefficient: 0.27). All observers were excellent in arranging the images according to the increasing dose reduction. CONCLUSIONS: Image quality of MSCT of the pelvis appears to be acceptable at 75 mAs and 140 kV with the dose reduced to 46% of the average value of the nation-wide survey of the German Roentgen Society in 1999 for this type of examination.

[MR imaging of the Achilles tendon: evaluation of criteria for the differentiation of asymptomatic and symptomatic tendons]. / MR-Tomografie der Achillessehne: Evaluation von Kriterien zur Differenzierung von asymptomatischen und symptomatischen Sehnen.

PURPOSE: The purpose of this study was to develop quantitative and qualitative MRI criteria to differentiate between healthy and pathological Achilles tendons. MATERIALS AND METHODS: 364 Achilles tendons were examined on a 1.5 T MRI scanner. 264 patients had Achilles tendon complaints, 100 asymptomatic Achilles tendons served as a control. T 1-weighted, T 2-weighted and a STIR sequence were performed in sagittal and axial orientation. Images were evaluated in consensus by two radiologists. Quantitative and qualitative criteria were assessed. A Mann-Whitney-U-Test and a regression analysis were used for statistical analysis. RESULTS: There were statistically significant differences between the patients with disorders and the control group concerning the depth (12.0 mm and 6.3 mm, p < 0.001) and length (83.2 mm and 45.9 mm, p < 0.001) of the tendon, the area of the tendon cross section (1.60 mm (2) and 061 mm (2), p < 0.001), as well as the length of the bursa retrocalcanea (8.3 mm and 5.3 mm, p < 0.001). There was a sensitivity of 97 % and a specificity of 91 % using a formula including the 3 criteria: tendon depth (A4), length of bursa (A5) and area of tendon (F). CONCLUSION: The measurement of the Achilles tendon and the binary-logistic regression analysis allow differentiation between normal and pathological Achilles tendons.

Postoperative monitoring of distal intraarticular radial fractures treated with osteosynthesis by means of multislice CT.

PURPOSE: This study evaluates multislice CT (MSCT) for the postsurgical control of intraarticular fractures of the distal radius. MATERIALS AND METHODS: In 131 patients conventional X-rays in two planes and MSCT were performed. In a consensus process two experienced radiologists judged conventional X-ray and computed tomography images in a random view. The correct position of the osteosynthetic material was assessed and it was ascertained whether an articular surface incongruity, a gap between two fracture fragments, or an intraarticular bone element was detectable. For each point of evaluation a confidence level of the evaluation was assessed on a five-point scale. RESULTS: Ninety patients were classified as having correct alignment and osteosynthesis according to conventional X-ray, while when using the findings from axial CT scans only, 82 patients, and after the addition of multiplanar re-constructions (MPR) only 73 patients were found to have almost proper alignment and osteosynthesis. In 42 patients dehiscence of the fragments was diagnosed with MSCT, but was not visualized by X-ray, leading to surgical revision in eight patients, confirming the diagnosis. In five patients an intraarticular position of intraarticular material was confirmed with MSCT and surgical revision. A significant advantage for the evaluation confidence level was achieved for MPRs in comparison with axial CT scans and X-ray. CONCLUSION: The marked diagnostic advantage with a high evaluation confidence level in comparison with conventional X-ray methods justify the use of MSCT during postoperative monitoring of articular radial fractures treated with osteosynthesis.

High-resolution in utero 3D MR imaging of inner ear microstructures in fetal sheep.

BACKGROUND AND PURPOSE: Developmental inner ear abnormalities can occur due to embryopathies as well as in the context of syndromal diseases like the CHARGE association. In severe cases, an early and definite in utero diagnosis is important for decision-making; here, fetal MR imaging can be a helpful tool. We present results of performing high-resolution MR imaging of the inner ear structures of fetal sheep in vivo. METHODS AND MATERIALS: Six ewes carrying singleton fetuses (mean gestational age, 120 days) were examined under general anesthesia at 1.5T. A 3D true FISP sequence with isotropic voxel size (0.7 mm) was applied; acquisition time was 2:35 minutes. For a standard of reference, 1 stillborn lamb of equivalent gestation age was examined. Image analysis was performed in consensus by 2 radiologists regarding the depiction of anatomic landmarks on a 5-point scale. Motion artifacts were quantified on a 3-point scale. RESULTS: The turns and modiolus of the cochlea as well as the origins of all 3 semicircular canals of the vestibular system of both sides could be reliably identified in every animal. Motion artifacts due to maternal breathing excursions or movements of the fetus were minimal. In case of breech presentation, the ventilation of the ewe had to be paused during the image acquisition to achieve acceptable results. CONCLUSIONS: High-resolution intrauterine MR imaging of the inner ear microstructures in an animal model is feasible. However, the acquisition time of the sequence applied is still too long to perform such measurement in a clinical setting.

[Dose reduction in high-resolution MSCT examinations of the chest for early detection of pneumonia in immunocompromised patients]. / High-Resolution-MSCT-Thoraxuntersuchungen zur Infiltratsuche: Untersuchung einer Dosisreduktion bei immunsupprimierten Patienten.

PURPOSE: The purpose of this study was to optimize high-resolution MSCT chest protocols for the evaluation of symptomatic immunosuppressed patients with suspected pneumonia using a dose-simulating program. MATERIALS AND METHODS: Using the MSCT (Siemens, Erlangen, Germany), 30 immunosuppressed patients with suspected pneumonia were examined with a low-dose HRCT of the chest (120 kV, 100 eff.mAs and collimation of 4 x 1 mm). A dose-simulating program was used to reconstruct the raw data at four different dose levels (70, 50, 35 und 25 mAs). For dose simulation for each mAs product, the correspondent noise level was added to the data. Images were generated with a slice thickness of 1 mm and 5 mm in the lung window. The images were then evaluated independently by two radiologists and graded on a scale of 1 to 3 points: 1 = no pneumonia, 2 = unclear, 3 = pneumonia. A receiver operating curve (ROC) analysis was performed to calculate the area under the curve (AUC). The actual dosage in mSv was calculated. The sensitivity and specificity were evaluated. RESULTS: Out of 30 patients, 7 had a normal chest finding and 23 had pneumonia. The area under the ROC curve (AUC) was 1.0 for every dosage and slice thickness. Infiltrates were detected correctly for all dosage levels. The sensitivity was 100 % for all dose levels and slice thicknesses. There was one false positive finding at 35 mAs and 1 mm slice thickness. At this dose level the specificity was reduced to 93 %. A reduction to 25 mAs had no influence on the detection of pneumonia. Thus, MSCT examinations of the chest can be performed with 25 mAs without missing the right diagnosis, resulting in an effective dose of 1.15 mSv (men), 1.5 mSv (women) and a CTDIvol of 2.5 mGy. CONCLUSION: For the evaluation of pneumonia in immunocompromised patients, MSCT examination of the chest can be performed with 25 mAs. Thus, radiation exposure was reduced to a quarter compared to the standard protocol.

Differentiation between benign and malignant findings on MR-mammography: usefulness of morphological criteria.

The purpose of this study was to evaluate the usefulness of morphological criteria in differentiating between benign and malignant lesions on MR-mammography. Fifty-three women (18-82 years) with 62 lesions scheduled for excisional biopsy underwent dynamic contrast-enhanced MR-mammography using fast 3D Gradient-Echo sequences in coronal orientation (axial orientation in seven patients). Histology revealed 44 malignant and 18 benign lesions. For each lesion, five radiologists evaluated four morphological features: lesion shape, irregularity of contour, homogeneity of contrast enhancement and presence of ring enhancement. For each feature a receiver operating characteristic (ROC) curve was generated with calculation of the area under the curve (AUC). Interobserver variability was evaluated by the kappa-coefficient. The most reliable morphological feature indicating malignancy was an irregular lesion contour with a sensitivity/specificity/AUC of 83%/76%/0.9 followed by inhomogeneous contrast enhancement (85%/42%/0.7) and the presence of ring enhancement (71%/53%/0.64). The average interobserver agreement for the different features ranged between 0.35 and 0.4. Morphological criteria are useful features in MR-mammography for differentiating between benign and malignant lesions. However, due to the relatively high interobserver variability, standardization of terminology is important.