[Forms of urinary diversion--methods and imaging findings]. / Formen der operativen Harnableitung: Methoden und bildgebende Diagnostik.

After cystectomy two principal types of urinary diversion are used for the surgical reconstruction of the urinary tract: incontinent and continent. In the continent type of urinary diversion, a differentiation must be made between those with and without catheterization for voiding. Besides urothelial cancer other reasons for urinary diversion include neurogenic bladder palsy (connatal or acquired) due to meningomyelocele or connatal diseases like bladder exstrophy. The main objective of the clinical urologist when selecting urinary diversion are to achieve continence and to preserve upper urinary tract function. Knowledge of the different forms of urinary diversion is critical for the exact interpretation of the images. This review presents the typical imaging techniques after a description of the basic surgical features of urinary diversion. CT urography and MR urography are becoming increasingly important as further imaging tools for controlling urinary diversions.

In vivo imaging in experimental preclinical tumor research--a review.

The multiparametric molecular cell and tissue analysis in vitro and in vivo is characterized by rapid progress in the field of image generation technologies, sensor biotechnology, and computational modeling. Fascinating new potentials in unraveling the detailed functions of single cells, organs, and whole organisms are presently emerging and permit the close monitoring i.e. tumor development or basic cell development processes with an unprecedented multiplicity of promising investigative possibilities. To answer basic questions of in vivo tumor development and progression fluorescence based imaging techniques provide new insights into molecular pathways and targets. Genetic reporter systems (eGFP, DsRED) are available and high sensitive detection systems are on hand. These techniques could be used for in vitro assays and quantified e.g. by microscopy and CCD based readouts. The introduction of novel fluorescent dyes emitting in the near infrared range (NIR) combined with the development of sensitive detector systems and monochromatic powerful NIR-lasers for the first time permits the quantification and imaging of fluorescence and/or bioluminescence in deeper tissues. Laser based techniques particularly in the NIR-range (like two-photon microscopy) offer superb signal to noise ratios, and thus the potential to detect molecular targets in vivo. In combination with flat panel volumetric computed tomography (fpVCT), questions dealing e.g. with tumor size, tumor growth, and angiogenesis/vascularization could be answered noninvasively using the same animal. The resolution of down to 150 microm/each direction can be achieved using fpVCT. It is demonstrated by many groups that submillimeter resolutions can be achieved in small animal imaging at high sensitivity and molecular specificity. Since the resolution in preclinical small animal imaging is down to approximately 10 microm by the use of microCT and to subcellular resolutions using ( approximately 1 microm) microscope based systems, the advances of different techniques can now be combined to "multimodal" preclinical imaging and the possibilities for in vivo intravital cytometry now become within one's reach.

[Value of MR-guided localization and biopsy in breast lesions]. / Stellenwert der MR-gestützten Lokalisation und Biopsie von Brustläsionen.

Contrast-enhanced dynamic MR mammography can provide important additional diagnostic information when performed for certain indications. When suspicious lesions are identified on MR mammography and cannot be reproduced using other imaging modalities, a decision must be made as to its management, i. e. further diagnostic work-up. One possibility is the short-term follow-up of such findings, resulting in higher costs and a possible delay in the start of treatment of a malignant lesion. An alternative to a follow-up is an MR-guided intervention. MR-compatible equipment has been developed for this purpose. This includes equipment specialized for percutaneous biopsy and preoperative localization. The following is an overview of the diagnostic value of MR-guided biopsy and preoperative localization including the relevant literature.

[Non-destructive, preclinical evaluation of root canal anatomy of human teeth with flat-panel detector volume CT (FD-VCT)]. / Zerstörungsfreie präklinische Evaluation der Wurzelkanalanatomie menschlicher Zähne mittels Flächendetektor-Volumen-CT (FD-VCT).

PURPOSE: Successful endodontic diagnostics and therapy call for adequate depiction of the root canal anatomy with multimodal diagnostic imaging. The aim of the present study is to evaluate visualization of the endodont with flat-panel detector volume CT (FD-VCT). MATERIALS AND METHODS: 13 human teeth were examined with the prototype of a FD-VCT. After data acquisition and generation of volume data sets in volume rendering technology (VRT), the findings obtained were compared to conventional X-rays and cross-section preparations of the teeth. RESULTS: The anatomical structures of the endodont such as root canals, side canals and communications between different root canals as well as denticles could be detected precisely with FD-VCT. The length of curved root canals was also determined accurately. The spatial resolution of the system is around 140 microm. Only around 73 % of the main root canals detected with FD-VCT and 87 % of the roots could be visualized with conventional dental X-rays. None of the side canals, shown with FD-VCT, was detectable on conventional X-rays. In all cases the enamel and dentin of the teeth could be well delineated. No differences in image quality could be discerned between stored and freshly extracted teeth, or between primary and adult teeth. CONCLUSION: FD-VCT is an innovative diagnostic modality in preclinical and experimental use for non-destructive three-dimensional analysis of teeth. Thanks to the high isotropic spatial resolution compared with conventional X-rays, even the minutest structures, such as side canals, can be detected and evaluated. Potential applications in endodontics include diagnostics and evaluation of all steps of root canal treatment, ranging from trepanation through determination of the length of the root canal to obturation.

[Retrospective analysis of a computer-aided detection (CAD) system in full-field digital mammography in correlation to tumor histology]. / Retrospektive Analyse eines computerassistierten Detektions-Systems (CAD) in der digitalen Vollfeldmammographie in Abhängigkeit von der Histologie.

PURPOSE: To evaluate the usefulness of a computer-aided detection (CAD) system in full-field digital mammography in correlation to tumor histology. MATERIAL AND METHODS: A total of 476 patients (226 patients with histologically proven malignant tumors, 250 healthy women) took part in this study. The mammograms were studied retrospectively, using the CAD system Image Checker. For 226 patients digital mammograms in MLO-projection were available. For 186 of these patients the CC-projection was also available. CAD markers that correlated with histologically proven carcinomas were considered to be true-positive markers. All other CAD markers were considered to be false-positive. Histologically proven carcinomas without markers were false-negative results. The dependence of the CAD markers placement upon the different carcinoma histologies was studied using the Chi-square test. RESULTS: No significant difference could be proven for the detectability of malignant breast lesions of different histologic types. For the detectability of ductal carcinoma in situ (DCIS), invasive ductal carcinoma (IDC), invasive lobular carcinoma (ILC), lobular carcinoma in situ (LCIS), tubular carcinoma and ductulo-lobular carcinoma, the true positives were 71.1 %, 75 %, 70.7 %, 70 %, 60 % and 80 %, respectively, in the MLO projection and 83.9 %, 75.9 %, 81.8 %, 77.8 %, 87.5 % and 33.3 %, respectively, in the CC projection. There was an average of 0.5 false-positive markers per mammographic image. CONCLUSION: The histologic type of carcinoma seems to have no influence on detectability when using the CAD system. The high rate of false-positive markers shows, however, the limited specificity of the CAD system and that improvements are necessary.

Applications and literature review of the BI-RADS classification.

The Breast Imaging Reporting and Data System (BI-RADS) of the American College of Radiology (ACR) is a tool created to reduce variability in the terminology used in mammographic reports. An illustration of mammographic examples from our institution interpreted according to the BI-RADS lexicon of the American College of Radiology (ACR) is presented. A literature review concerning the usefulness and limitations of the BI-RADS lexicon is given.

[Diagnosis and classification of calcaneal fractures in computed tomography]. / Diagnostik und Klassifikation von Kalkaneusfrakturen in der Computertomographie.

PURPOSE: To compare image quality of single-slice spiral CT (SSCT) and multislice spiral CT (MSCT) in the diagnosis and classification of calcaneal fractures and to present a rapid and precise algorithm for the classification system of Stuermer. MATERIALS AND METHODS: In 102 patients with 124 calcaneal fractures, spiral CT was performed, in 82 cases as SSCT with a slice thickness (SD) of 3 mm, a table speed (TS) of 3 - 4 mm/rot and an increment of 1.5 mm. In 42 cases, patients were scanned using MSCT (SD of 1.25 mm, increment 0.8 mm). For these examinations, 2 different scan protocols were used, with a TS of 3.75 mm/rot in one group (n = 21) and a TS of 7.5 mm/rot in the other group (n = 21). The image quality of axial sections and reconstructed images was assessed on a scale from 1 to 5 (1 = very good; 5 = insufficient). The fractures were evaluated using a classification system according to Stuermer, which assigns three main groups (A/B/C) and three subtypes (1/2/3). RESULTS: MSCT had substantial advantages over SSCT with respect to scan time and image quality, especially for multiplanar reformatting (median 1.5 versus 4.0). TS showed no significant influence on the image quality. The standardized evaluation of the images enabled a classification of fractures within 5 minutes. All fractures could be assigned to the different types and subtypes. This classification system takes into account the severity of the fracture and the therapeutic approach. The most common type (90 of 124 fractures) were "joint depression" fractures (type C), which were treated by surgery in 92 %. Type A fractures were treated conservatively in 72 %. CONCLUSION: Spiral CT, especially MSCT, allows rapid diagnosis and precise classification of calcaneal fractures, achieved with high quality multiplanar reformatting. The presented classification in different fracture types and subtypes allows an adequate planning of therapy.

[Flat-panel detector-based computed tomography: accuracy of experimental growth rate assessment in pulmonary nodules]. / CT-Bildgebung mit einem Flachbilddetektor: experimentelle Untersuchungen zur Wachstumsratenbestimmung von Lungenrundherden.

PURPOSE: To determine the performance of an a-Si/CsJ flat-panel detector-based volumetric computed tomography (VCT) prototype in volumetry of synthetic nodules in a pulmonary phantom, and to assess VCT accuracy in the assessment of hypothetic tumor growth rates based on predefined tumor doubling times. METHODS: The true volumes of 50 synthetic nodules (diameter range = 1.36 - 5.34 mm) were determined and VCT volumetry was performed before and after isovolumetric deformation of the nodules. The percent measurement error (PMF) was calculated as the percent difference of the measured from the true volume. Based on the PMF, the minimum interval between two scans was determined that would be needed to depict tumor growth corresponding to the minimum number of required follow-up days (FUDs). Based on predefined tumor doubling times (VDT) FUDs were determined before and after nodule deformation. RESULTS: Measured volumes of undeformed and deformed nodules of 0.99 - 20.05 mm (3) differed significantly from corresponding true volumes (p = 0.002 - 0.004). The PMFs of these nodules significantly exceeded the values measured in larger nodules (p = 0.0001 - 0.0029). In addition, PMFs were significantly lower before than after deformation (1.33 - 7.14 % and 0.61 - 11.09 %, respectively; p = 0.002). For theoretical VDTs of 177 and 396 days, the calculated FUDs for detection of tumor growth were 19.1 and 42.7 days before deformation, and 30.2 and 67.6 days after deformation for nodules < 2 mm, respectively. CONCLUSION: VCT allows for accurate volumetry of smallest pulmonary nodules and may become a valuable clinical tool for depiction of tumor growth of even small lesions within very short scan intervals.

[Diagnostic performance of retrospectively ECG-gated multislice CT of acute pulmonary embolism]. / Diagnostischer Stellenwert der retrospektiven EKG-Triggerung in der Mehrschicht-Spiral-CT der akuten Lungenembolie.

AIM: This study determined the diagnostic performance of ECG-gated MSCT in comparison with conventional MSCT. MATERIALS AND METHODS: Forty-five consecutive patients prospectively underwent ECG-gated (group 1, n = 23) or non-ECG-gated (group 2, n = 22) 8-slice MSCT of the pulmonary arteries. Image data were interactively evaluated by three independent chest radiologists with respect to the presence of emboli at different arterial levels, and with regard to cardiac motion artefacts. Consensus reading by two experienced chest radiologists served as diagnostic gold standard. ROC analysis was carried out for the different vascular sections. RESULTS: Twenty-five patients (56 %) were diagnosed to have pulmonary embolism (13 from group 1, 12 from group 2). Cardiac motion artefacts were significantly more frequent in group 2 (70 % in group 2 versus 13 % in group 1, p < 0.05). There was no significant difference between the two groups in the overall sensitivities (0.92 vs. 0.95) and specificities (0.92 vs. 0.98) or in sensitivities and specificities at any assessed pulmonary arterial level. CONCLUSION: ECG-gated MSCT pulmonary angiography does not significantly influence the diagnostic performance of MSCT in these patients. Therefore no recommendation for routine clinical practice can be given.

ECG-gated multislice spiral CT for diagnosis of acute pulmonary embolism.

AIM: The purpose of this study was to determine the feasibility of echocardiogram (ECG)-gated multi-slice CT angiography (MCTA) in patients with clinical suspicion of acute venous thromboembolism (VTE), to investigate the effect of ECG-gating on cardiac motion artefacts, and to determine the diagnostic reader agreement of ECG-gated MCTA in comparison with conventional MCTA. MATERIALS AND METHODS: Forty-eight consecutive patients were prospectively enrolled and randomly underwent ECG-gated (n=25, group 1) or non-ECG-gated (n=23, group 2) eight-slice pulmonary MCTA. Image data were evaluated by three independent chest radiologists with respect to the presence or absence of emboli at different arterial levels (main, lobar, segmental, and subsegmental arteries), and with regard to cardiac motion artefacts. Statistical tests used to calculate inter-observer agreement were weighted kappa statistics, extended kappa statistics and confidence indices indicating three-reader agreement accuracy. RESULTS: Twenty-seven patients (56.3%) were diagnosed to have pulmonary embolism (13 from group 1, 14 from group 2). Cardiac motion artefacts were significantly more frequent in group 2 (70% in group 2 versus 13% in group 1, p=0.0001). The overall diagnostic agreement was excellent with both MCTA techniques (three-reader confidence index for all vascular territories: 0.76 and 0.84 for groups 1 and 2, respectively (extended kappa=0.69 and 0.78, respectively); three-reader confidence index for diagnosis of VTE: 0.94 and 0.85 for groups 1 and 2, respectively (extended kappa=0.91 and 0.73, respectively), weighted kappa=0.81-0.83 and 0.92-0.95 for groups 1 and 2, respectively, and did not differ significantly between the two groups. In addition there was no significant difference of inter-observer agreement in either group at any assessed pulmonary arterial level. CONCLUSION: ECG-gated pulmonary MCTA is feasible in patients with clinical suspicion of VTE. However, ECG-gated image acquisition did not influence the diagnostic reader agreement accuracy and inter-observer agreement of MCTA. Hence, it does not appear to be advantageous for the MCTA diagnosis of pulmonary embolism.

[Contrast-enhanced MR angiography of the arterial and portovenous system of the liver with varying concentrations of contrast medium]. / Kontrastmittel-gestützte 3D-MR-Angiographie des arteriellen und portalvenösen Gefässsystems der Leber mit unterschiedlicher KM-Konzentration.

PURPOSE: To evaluate the diagnostic value of a higher concentrated contrast medium (gadobutrol) for contrast-enhanced MRA of the hepatic arteries and portovenous system. MATERIALS AND METHODS: The examinations were performed on a 1.5-Tesla whole body imaging system (Magnetom Symphony Quantum, Siemens) with a 30-mTesla/m gradient field strength using a phased-array body coil. A 3D FLASH sequence (TR/TE/FA 3.88 ms/1.44 ms/25(3)) was used imaging the hepatic arteries and portovenous system after determination of the circulation time. The study included 50 patients, with 25 patients (group 1) injected with 0.2 mmol Gd-GTPA/kg body weight and 25 patients (group 2) injected with 0.1 mmol gadobutrol/kg body weight. The signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) were calculated for both groups. The image quality was graded by three radiologists on a 5-point scale. RESULTS: The highest SNR was measured in group 1, with no statistically significant differences of the SNR in the abdominal aortal, coeliac trunk and common hepatic artery. CNR was also similar in both groups. Likewise, portal, superior mesenteric and splenic veins showed no statistically significant differences. All cases were found to have a good image quality. CONCLUSION: For MRA of the hepatic arteries and the portal veins, the higher concentrated Gd-DTPA contrast medium gadobutrol can be used at half the dosage recommended for the standard Gd-DTPA contrast medium.

MRI in the evaluation of müllerian duct anomalies.

OBJECTIVE: Müllerian duct anomalies (MDAs) result from nondevelopment or nonfusion of the müllerian ducts and occur in 1-5% of women. Accurate diagnosis of the various subtypes is of great importance as MDAs are frequently associated with a broad variety of clinical symptoms. Recently, evidence arose that MRI might play a major role in diagnosis of MDAs. We present four cases of diverse subtypes of MDAs and the corresponding MRI findings. MATERIALS AND METHODS: Patients (n = 4) with clinical suspicion of MDAs were examined with MRI. Coronal and transaxial T1- and T2-weighted images were acquired. Diagnosis was made and patients were grouped according to the American Fertility Society's classification. Patients underwent laparoscopy or laparotomy in order to confirm the diagnosis. RESULTS: MRI revealed MDAs in all patients. In detail, one patient was diagnosed with hypoplastic uterus, one with unicornuate uterus with a noncommunicating rudimentary horn, one with bicornuate uterus bicollis with a double vagina and one with septate uterus. MRI diagnosis was correct in all cases, as confirmed by subsequent surgical intervention. CONCLUSION: MRI is a valuable tool in diagnosis of MDA subtypes. Its use will help to spare patients mutilating surgery and to prevent pregnancy-associated complications.

Dose reduction in full-field digital mammography: an anthropomorphic breast phantom study.

The aim of this study was to evaluate the potential for radiation dose reduction by using other beam qualities in full-field digital mammography (FFDM) compared with screen-film mammography (SFM). FFDM was performed using an amorphous silicon detector with a caesium iodide scintillator layer (Senographe 2000D, GE, Milwaukee, USA). SFM was performed using a state-of-the-art conventional system (Senographe DMR, GE, Milwaukee, USA) with a dedicated screen-film combination. An anthropomorphic breast phantom with superimposed microcalcifications (50-200 microm) was used to evaluate the detectability of microcalcifications. Contact mammograms and magnification views (m=1.8) performed with both the digital and the screen-film system were compared. Images were exposed automatically. Molybdenum/Molybdenum (Mo/Mo) anode-filter combination, 28 kVp and 63 mAs were selected by the automatic optimization of parameters (AOP) of the conventional system. This exposure protocol (protocol A) was also used as baseline for the digital system. Dose reduction in digital mammography was achieved by using protocol B with Mo/Rh and 31 kVp and protocol C with Rh/Rh and 32 kVp. The detectability of microcalcifications was assessed by 3 experienced readers with a confidence level ranging from 1 to 5. A receiver operating characteristic (ROC) analysis was performed. In protocol A the area under the ROC-curve (A(z)) for contact views performed by the screen-film system was 0.64 and for those performed with the FFDM system 0.68. The A(z) values were 0.74 in protocol B and 0.65 in protocol C for the digital system. For the conventional and digital magnification views A(z) values were 0.71 and 0.79, respectively. For protocol B the A(z) value was 0.81 and for protocol C it was 0.76. There is no statistically significant difference in the A(z) values for the different protocols in digital mammography and no significant difference from the screen-film system. A potential for dose reduction by using other beam qualities seems to be possible with this digital system.

[The contribution of different postprocessing methods for multislice spiral CT in acute pulmonary embolism]. / Stellenwert unterschiedlicher Nachverarbeitungsverfahren in der Mehrschicht-Spiral-CT der akuten Lungenembolie.

PURPOSE: To investigate the value of different postprocessing algorithms for multislice spiral CT (MSCT) in diagnosing acute pulmonary embolism. MATERIALS AND METHODS: Forty-eight patients with suspected pulmonary embolism prospectively underwent MSCT using an 8-slice spiral CT. Using a confidence level on a three-point scale, three radiologists reviewed 2-mm and 5-mm axial slices, 5-mm and 10-mm axial maximum intensity projections (MIP) and 2-mm coronal slices as well as interactively generated multiplanar reformatted images. A subsequent consensus reading of the primary 1.25-mm axial slices served as gold standard. ROC analysis was applied to the various vascular sections. RESULTS: The ROC analysis revealed a higher diagnostic accuracy of the 2-mm axial sections as compared to the 5-mm axial slices (Az = [0.988;0.976] vs. Az = [0.988;0.802]). Coronal and multiplanar reformations also showed excellent diagnostic accuracy (Az = [0.972;0.949] and Az = [0.997;0.951], respectively) and were significantly superior to the 5-mm axial slices through the segmental and subsegmental arteries (p=0.05). MIP showed the weakest diagnostic accuracy (Az = [0.967;0.802] for 5-mm MIP; Az = [0.879;0.781] for 10-mm MIP). CONCLUSION: Thin axial slices as well as coronal and multiplanar reformations are superior to thick axial slices in the diagnosis of acute pulmonary embolism. MIP is not suited for accurate diagnosis of pulmonary embolic disease.

Ultrasound-guided laser interstitial thermo therapy for treatment of non-resectable primary and secondary liver tumours--a feasibility study.

AIM: Therapeutic options for primary and secondary liver tumours not suitable for resection or transplantation are limited. In this palliative situation, the scope of ablative therapeutic procedures has improved. Laser interstitial thermotherapy is a minimal invasive procedure for local tumour destruction within solid organs. This pilot study reports initial clinical experience using ultrasound-guided percutaneous laser interstitial thermotherapy. METHODS: Sixty patients between the ages of 34 and 78 years with non-resectable primary and secondary liver tumours were treated palliatively with Nd:YAG laser interstitial thermotherapy. High resolution abdominal ultrasound with power duplex was used to control the placement and coagulation procedure. RESULTS: In all cases, sonographic imaging allowed exact placement of the laser probe and verification of thermocoagulation by a resulting hyperechogenic signal enhancement. The maximum diameter of laser-induced destruction measured 5 cm. Ultrasound with power duplex and echo enhancer, CT or MRI scans indicated necrosis of treated tumour lesions. No serious adverse event occurred and 30-day-mortality was zero. CONCLUSIONS: Ultrasound-guided laser interstitial thermotherapy is safe and reliably ablates primary and secondary liver tumours. The combination of high resolution ultrasound and laser therapy facilitates a minimally invasive but elaborate treatment. Besides chemotherapy, this procedure could be a useful palliative treatment to control the mass of liver tumours unsuitable for resection or transplantation.

Value of F-18 FDG hybrid camera PET and MRI in early takayasu aortitis.

Takayasu aortitis (TA) is a chronic inflammatory and fibrotic vasculitis of large- and medium-sized arteries. Early stages of the disease show a panarteritis and inflammatory wall thickening of the aorta and its branches, whereas advanced (fibrotic) stages comprise stenosis, aneurismatic transformation and occlusion. Magnetic resonance imaging visualises early-stage disease with high accuracy and is considered to be the method of choice in the diagnosis of TA. The aim of this article is the detailed comparison of FDG-PET performed with a hybrid camera and MR imaging in five patients with early TA. Five patients (median age 60 years) were enrolled during an ongoing prospective study on [18F]2'-deoxy-2-fluoro-D-glucose (FDG) hybrid camera PET in patients with fever of unknown origin (FUO). These patients underwent MR imaging after establishing the diagnosis of TA. Abnormal FDG uptake in the wall of the aorta was noted in all patients. The bracheocephalic artery and the common carotid arteries were visualized in 3 cases. Increased uptake of the subclavian artery was found in 3 patients and in 4 patients pathological uptake was noted in the ilio-femoral vessels. Of 34 vascular regions studied, 26 (76%) showed elevated FDG uptake. On transversal MR images vessel wall thickening and contrast enhancement of the thoracic aorta was found in 4 patients (ascending aorta/aortic arch: n=2; descending aorta: n=3; abdominal aorta: n=1). Additionally, vessel wall pathologies of the subclavian and the common carotid arteries could be shown in 1 patient and in another patient in the ilio-femoral arteries. No abnormalities were found using contrast-enhanced MR angiography. Of 28 vascular regions studied, 9 (32%) showed vasculitis on MRI. The FDG-PET is a suitable whole-body screening method in the primary diagnosis of early TA, especially in those cases with early disease that present with uncharacteristic symptoms such as FUO. Both MRI and MRA remain indispensable in the exact determination of the pathomorphological changes and in the documentation of complications such as stenosis, aneurismatic transformation and occlusion.

Computer-aided detection in direct digital full-field mammography: initial results.

For the first time, full-field digital mammography (FFDM) allows computer-aided detection (CAD) analysis of directly acquired digital image data. The purpose of this study was to evaluate a CAD system in patients with histologically correlated breast cancer depicted with FFDM. Sixty-three cases of histologically proven breast cancer detected with FFDM (Senographe 2000D, GE Medical Systems, Buc, France) were analyzed using a CAD system (Image Checker V2.3, R2 Technology, Los Altos, Calif.). Fourteen of these malignancies were characterized as microcalcifications, 37 as masses, and 12 as both. The mammographic findings were categorized as BI-RADS 3 (n=5), BI-RADS 4 (n=17) and BI-RADS 5 (n=40). The sensitivity for malignant lesions and the rate of false-positive marks per image were calculated. The sensitivity and its 95% confidence interval (CI) were estimated. The sensitivity of the CAD R2 system in breast cancer seen on FFDM was 89% for microcalcifications [CI(95%)=(70%; 98%)] and 81% for masses [CI(95%)=(67%; 91%)]. As expected, the detection rate was higher in lesions categorized as BI-RADS 5 (37 of 40) compared with lesions categorized as BI-RADS 4 (11 of 17). In the group categorized as BI-RADS 3 the detection rate was 4 of 5 lesions; however, this group was very small. The rate of false-positive marks was 0.35 microcalcification marks/image and 0.26 mass marks/image. The overall rate of false-positive marks was 0.61 per image. CAD based on FFDM provides an optimized work flow. Results are equivalent to the results reported for CAD analysis of secondarily digitized image data. Sensitivity for microcalcifications is acceptable and for masses is low. The number of false-positive marks per image should be reduced.

Comparative study in patients with microcalcifications: full-field digital mammography vs screen-film mammography.

The goal of this prospective study was to compare a full-field digital mammography system (FFDM) to a conventional screen-film mammography system (SFM) for the detection and characterization of microcalcifications. Fifty-five patients with 57 isolated microcalcification clusters were examined using a FFDM system (Senographe 2000D, GE Medical Systems, Milwaukee, Wis.) and a SFM system (Senographe DMR, GE Medical Systems, Milwaukee, Wis.). A conventional screen-film mammogram and a digital contact mammogram were obtained of each cluster. The image quality and the number of calcification particles were evaluated, and a characterization (BI-RADS 1-5) of microcalcifications was given by four experienced readers. Histopathology revealed 16 benign lesions (sclerosing adenosis, dysplasia, hamartoma, radial scar) in 15 patients and 21 malignant tumors (in situ carcinoma, invasive carcinoma) in 20 patients. Twenty patients had benign changes verified by long-term follow-up. Image quality of FFDM was assessed as superior to SFM in more than 50% of the cases. The FFDM showed more calcifications in 41% of all cases. Sensitivity and specificity for FFDM vs SFM were 95.2 vs 91.9% and 41.4 vs 39.3%, respectively. Moreover, FFDM demonstrated a higher diagnostic accuracy (deviation: 0.86 BI-RADS steps) compared with FSM (deviation 0.93 BI-RADS steps). The FFDM system with a 100- micro m pixel size provides better image quality than SFM in patients with mammographic microcalcifications. The FFDM has a higher sensitivity and a higher reliability in characterizing microcalcifications.

Magnification mammography: a comparison of full-field digital mammography and screen-film mammography for the detection of simulated small masses and microcalcifications.

The objective of this study was a comparison of a full-field digital mammography (FFDM) system and a conventional screen-film mammography (SFM) system with respect to the detectability of simulated small masses and microcalcifications in the magnification mode. All images were obtained using 1.8 times magnification. The FFDM images were obtained at radiation dose levels of 1.39, 1.0, 0.7, 0.49 and 0.24 times that of the SFM images. A contrast-detail phantom was used to compare the detection of simulated lesions using a four alternative forced-choice reader study with three readers. The correct observation ratio (COR) was calculated as the fraction of correctly identified lesions to the total number of simulated lesions. Soft-copy reading was performed for all digital images. Direct magnification images acquired with the digital system showed a lower object contrast threshold than those acquired with the conventional system. For equal radiation dose, the digital system provided a significantly increased COR (0.95) compared with the screen-film system (0.82). For simulated microcalcifications, the corresponding difference was 0.90 to 0.72. The digital system allowed equal detection to screen-film at 40% of the radiation dose used for screen film. Digital magnification images are superior to screen-film magnification images for the detection of simulated small masses and microcalcifications even at a lower radiation dose.

[Multislice helical CT (MSCT) for mid-facial trauma: Optimization of parameters for scanning and reconstruction]. / Mehrschicht-Spiral-CT (MSCT) beim Mittelgesichtstrauma: Optimierung der Aufnahme- und Rekonstruktionsparameter.

PURPOSE: To determine the optimal scan parameters in multislice helical CT (MSCT) of the facial bone complex for both axial scanning and multiplanar reconstructions. MATERIAL AND METHODS: An anthropomorphic skull phantom was examined with a MSCT. Axial scans were performed with continuously increasing collimations (4 x 1.25 - 4 x 2.5 mm), tube current (20 - 200 mA) and table speeds (3.75 mm/rot. and 7.5 mm/rot.). Multiplanar reconstructions in coronal and parasagittal planes with different reconstruction increment and slice thickness were evaluated in terms of image noise, contour artifacts and visualisation of anatomical structures. RESULTS: The best image quality was obtained with a collimation of 4 x 1.25 mm and a table speed of 3.75 mm/rot. A reconstruction increment of 0.6 mm achieved the best time to image quality relation. With these parameters the bone structures were depicted in an optimal way without artifacts. The tube current could be reduced to 50 mA without significant loss of image quality. The optimized protocol was used for regular routine examinations in patients with facial trauma (n = 66). CONCLUSIONS: Low-dose MSCT using thin collimation, low table speed and small reconstruction increments provides excellent data for both axial images and multiplanar reconstructions in patients with facial trauma. An additional examination in coronal orientation is therefore no longer necessary.