[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.

[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.

[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.

[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.

Magnetic resonance guided localization and biopsy of suspicious breast lesions.

Contrast-enhanced magnetic resonance imaging (MRI) is being used increasingly as a complementary diagnostic modality in breast imaging of preselected patients. The exclusion of multicentricity before surgery and the differentiation between a scar and a carcinoma are well-accepted indications of this method. Problems result when suspicious lesions found with MRI cannot be visualized with mammography or ultrasonography. In these cases, MRI-based guidance systems are needed to guide needle biopsy or allow localization of the lesion before surgery. At our institution, 167 MR-guided interventions (35 percutaneous biopsies and 132 preoperative localizations) have been performed with the use of different types of add-on devices during the past 3 years. Percutaneous biopsy (31 fine needle aspiration and four core biopsies) revealed 24 benign and 8 malignant lesions, 3 biopsies were insufficient. Histologic examination after MR-guided wire localization showed benign findings in 68 lesions (52%) and malignancy in 64 lesions (48%). Technical aspects, experiences, advantages, and disadvantages of our system as well as those of other devices are reported and discussed. MR-compatible equipment for interventions of the breast is demonstrated. In conclusion, we perform MR-guided interventions of the breast routinely in indicated cases at a rate of approximately 3-5% for all patients undergoing diagnostic contrast-enhanced MRI of the breast.

Electrocardiograph-triggered two-dimensional time-of-flight versus optimized contrast-enhanced three-dimensional MR angiography of the peripheral arteries.

We determined whether the accuracy of magnetic resonance angiography (MRA) in the peripheral run-off vessels can be improved by using contrast-enhanced (CE) three-dimensional (3D) technique in comparison to electrocardiograph (ECG)-triggered two-dimensional (2D) time-of-flight (TOF) technique. In a prospective study 20 patients with occlusions of the pelvic and/or femoral arteries underwent a CE 3D MRA (repetition time (TR): 5 ms, (TE) echo time: 2 ms, flip angle (FA): 30 degrees ) and an ECG-triggered 2D time-of-flight (TOF) technique (TR: 408 resp. 608 ms, TE: 7 ms, FA: 70 degrees) of the run-off vessels on a 1.5 T MR system. Each patient received a contrast material volume of 0.15 mmol/kg of body weight of gadolinium (Gd)/DTPA using an automatic injector. The tube system to the patient was flushed by 50 mL of a saline solution applied with the same injection rate as the contrast material administration. The start of the 3D MR sequence was tailored individually to the applied contrast material after determination of circulation times by a prior bolus. All patients underwent each conventional or digital arteriography for comparison, as well. The visualization of the run-off vessels was ranked on a scale of 0-3 (0 = poor, 1 = fair, 2 = good, 3 = excellent) by three blinded reviewers. They also graded the vascular segments as either occluded or significantly altered (>50% reduction in diameter) or free of significant stenosis. CE 3D MRA was significantly faster in imaging the run-off vessels in comparison to the ECG-triggered 2D TOF technique. All 160 vascular segments were visualized with the 3D method, whereas only 142/160 segments were seen with 2D technique. The resulting image quality ranking of all vascular segments was significantly higher (p < 0.05) using CE 3D MRA (2.8) than with the 2D TOF technique (2.4). The detection of the stenoses was possible with both techniques. The grading of seven of seven stenoses was correct with 3D method and in five of seven cases with the 2D TOF technique. All vessel occlusions were detected by using both techniques. Small collaterals were visualized in more detail with the CE 3D MR angiography. These data demonstrate an improvement in image quality and accuracy of MRA of the peripheral arteries using a CE 3D technique in comparison to an ECG-triggered 2D TOF sequence.

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.

Storage phosphor direct magnification mammography in comparison with conventional screen-film mammography--a phantom study.

Contact mammography with current photostimulable storage phosphors is hampered by its low spatial resolution. Detail visualization can be improved by geometric magnification radiography which enlarges small details to exceed inherent image noise. This study compares storage phosphor mammography using a dedicated direct magnification system with state-of-the-art conventional screen-film mammography. Storage phosphor direct magnification survey views (1.7x) and spot views (4x) were obtained with a prototype mammography unit providing focal spot sizes of 120-40 microns. Conventional technique screen-film survey views (1.1x) and spot views (1.8x) served as comparison. A contrast detail study and a receiver operating characteristic (ROC) analysis using an anthropomorphic breast phantom with superimposed microcalcifications was performed. Contrast detail resolution in the digital and conventional survey views were equivalent. For the spot views, contrast detail resolution was significantly higher with the digital technique (p < 0.001). ROC analysis of 400 observations demonstrated a significantly higher performance (p < 0.001) with digital images versus conventional screen-film mammograms. The area under the ROC curve (Az) in the digital survey views was 0.76 +/- 0.07 versus 0.59 +/- 0.02 in the conventional technique. In digital spot views, Az was 0.82 +/- 0.07 as compared with 0.66 +/- 0.04 in the conventional spot views. These results suggest that storage phosphor digital mammography in conjunction with direct geometric magnification technique may be superior to conventional screen-film mammography in the detection of microcalcifications.

A comparison of conventional mammographic magnification, ultra high magnification and industrial magnification radiography in the radiographic detection of microcalcifications within core biopsies of the breast.

The objective was to compare conventional magnification radiography (CMR), ultra high magnification radiography (UHMR) and industrial magnification radiography (IMR) in the detection of microcalcifications in breast core biopsies. 440 core biopsies were examined in 1.8-fold CMR and in 7-fold UHMR using a prototype unit. A subgroup of 59 core biopsies were also examined in 10-fold IMR. Number, size, and demarcation of microcalcifications, as well as tissue contrast, were evaluated. Only 67% of the microcalcifications seen with UHMR were detected by CMR and 78% of the core biopsies showing calcifications in UHMR were calcified in CMR. Only 38% and 58% of microcalcifications verified by IMR were identified by CMR and UHMR, respectively. 47% and 63% of the core biopsies showing calcifications in IMR were calcified in CMR and UHMR, respectively. Tissue contrast of IMR was superior to both other modalities. On the other hand, increased cost and time will probably prohibit the use of IMR for specimen radiography in routine clinical examinations. In conclusion, UHMR identifies substantially more core biopsies with microcalcifications than CMR, thus potentially reducing the number of core biopsies needed for histological analysis. IMR allowed the detection of approximately 50%/160% more microcalcifications than UHMR/CMR, thus rendering it the reference mode.

3D MR angiography of the entire aorta: modified application of the body-phased array coil for a single-shot technique.

OBJECTIVE: Evaluation of different contrast-enhanced MR angiography imaging protocols for visualization of the entire aorta in breath-hold technique. METHODS AND PATIENTS: Three different CE (0.15 mmol/kg) MRA protocols were evaluated by phantom and patient studies: (1) two separate MRA with conventional application of the body-phased array coil; (2) a single-shot MRA with modified application of the body-phased array coil; (3) a single-shot MRA with the body coil. Duplex sonography, CTA and DSA were used as standard of reference. RESULTS: In all examinations the entire aorta could be visualized. The best SNR was acquired with protocol (1). The SNR of protocol (2) was reduced if the sagittal body diameter of the patient was greater than 20 cm and decreased significantly with diameters over 30 cm. By the use of protocol (3) the SNR was notably poor. The quality scored for the visualization of the entire aorta was 97.5% (protocol 1); 92.5% (protocol 2); and 80.0% (protocol 3). CONCLUSION: In most cases the modified application of the body-phased array coil allows the imaging of the entire aorta as a single-shot 3D CE MRA in diagnostic quality.

[Method and value of the opacified intestine in the computed tomography of abdomen (author's transl)]. / Methodik und Wert der Darmkontrastierung bei der abdominellen Computertomographie.

In the examination of the intestine CT can deliver further information about diseases transgressing the intestinal wall or bordering on it. Sometimes, however, bowel loops filled with liquid can scarcely be distinguished from abdominal abnormalities. In these cases contrast material given orally or as an enema can facilitate the distinction and the identification of pathological patterns. The method of opacifying bowel loops is presented and demonstrated by several examples. Its value as well as its limits are discussed.

[Radiologic investigations following abdomino-perineal resection of the rectum (author's transl)]. / Radiologische Diagnostik nach abdomino-perinealer Rektumamputation.

After abdominoperineal resection of the rectum specific alterations due to operation and disease can be distinguished. In over eighty percent the ureters and the urinary bladder are concerned. The topography of the small-intestine in the sacral cavity reveals alterations of the pelvic floor which generally are local recurrences of carcinoma. In both examinations special importance has to be laid on a lateral view of the pelvis. Indications and results of supplementary examinations are discussed. Computed tomography will deliver additional informations for the diagnosis of recurrent carcinoma; the value of CT is checked at the moment. Considering the amount and importance of treatable illness following resection of the rectum a standardized program for examination seems inevitable. Our experience with over 400 cases is, that this program can reveal important informations for postoperative care which up to now has often been underestimated, even from a radiologic point of view.

[Bühler's anastomosis (author's transl)]. / Die Bühlersche Anastomose.

The arc of Bühler between the celiac and superior mesenteric arteries has to be considered as an embryological persistence of the portion of the ventral longitudinal anastomosis. The collateral development of the anastomosis refers to a different hemodynamic in the upper visceral arteries. We discovered the arc of Bühler in 14 cases among 340 selective celiac and superior mesenteric arteriographic studies. Its existence permits conclusions about further angiographic procedures and facilitates the interpretation of visceral collaterals.

[Diffuse infiltrating lipomatosis. A subentity of intrapelvic fatty tumor]. / Die diffus infiltrierende Lipomatosis. Eine Subentität intrapelviner Fettgeschwülste.

Nineteen patients with various types of lipoma in the pelvis are described. Clinical findings, radiological examinations, and follow-up studies constitute a particular type of lipoma, diffuse infiltrating lipomatosis; this can be distinguished from other fatty tumours because of its localisation, extent, therapeutic results and long course. Computed tomography enables us to differentiate simple lipomatosis pelvis from diffuse infiltrating lipomatosis. Histological examination is essential for excluding a liposarcoma. Growth or malignant change of diffuse infiltrating lipomatosis is most easily recognized by computed tomographic serial observation.

[Computed tomography of soft tissue sarcomas (author's transl)]. / Computertomographie bei Weichteilsarkomen.

CT findings in 50 patients with histologically verified soft tissue sarcomas are presented. In nearly all the cases the cross-sectional view and the higher resolution of density make it possible to determine exactly location of the tumors, their size and relationship to adjacent structures. Thus CT opens a new dimension, which is of great value for staging and therapy treatment planning. The high rank of CT in the follow-up after therapy and the detection of recurrent tumor is demonstrated. The contribution of CT, however, to the anatomic characteristics and its prospective value with the regard to soft tissue tumor is less important. Further limits of the method are discussed.

[Serial computed tomography -- methods and early experience (author's transl)]. / Serien-Computertomographie -- Methodik und erste Erfahrungen.

Serial computed tomography following intravenous bolus injection of contrast agent is an important development in computed tomographic diagnosis. The technical necessities and methods of examination are discussed. Our experience with 108 examinations is evaluated. The additional information in terms of morphology and function is described.

[The tilted screen-cassette ("grid cut-off" effect). A problem of bedside thoracic diagnosis]. / Die verkippte Rasterkassette ("grid cut-off"-Effekt). Ein Problem der bettseitigen Thoraxdiagnostik.

Tilting of a grid during portable radiography leads to uneven exposures, and errors greater than 3 degrees can lead to errors in interpretation. Differentiation from abnormal findings can be made by recognising exposure difference of extrathoracic comparable areas. The difficulties caused by tilting of the grid can be reduced by increasing the film focus distance and by using suitable grids. A new cassette holder with an integrated balance makes it possible to correct tilting of the grid rapidly and effectively. This results in improved image quality which can be applied not only to conventional exposure systems but is also of advantage when using digital methods.

[Diagnostic imaging in hepatosplenic candidiasis]. / Bildgebende Diagnostik bei hepatolienaler Candidose.

Hepatosplenic candidiasis is a severe complication encountered in immuno-compromised patients. Different imaging techniques can establish the diagnosis. After an introduction to the pathophysiological and clinical principles, the role of plain radiography, radionuclide scans, ultrasound, computed tomography and magnetic resonance imaging is discussed.

[Initial experiences with the MR "magnitude contrast angiography of the lower extremities]. / Erste Erfahrungen mit der MR-"Magnitude Contrast Angiography" an den unteren Extremitäten.

45 patients with occlusive peripheral vascular disease were examined by MR angiography in a retrospective study. A FISP 3D sequence was used by acquiring a rephased and a dephased data set. The individual slices were post-processed by using a maximum-intensity-projection algorithm. The MRA results of the popliteal and tibioperoneal arteries were compared to conventional or digital angiography. In comparing these techniques MR angiography cannot be accepted for pre- and postoperative staging of patients with occlusive peripheral vascular disease. In future new MRA techniques may be useful in postoperative staging of patients with peripheral vascular stenosis.

[Arterio-venous fistula of the liver. Computer tomographic diagnosis (author's transl)]. / Arteriovenöse Fisteln in der Leber. Computertomographische Diagnostik.

By using serial computer tomography, an arterio-venous fistula of the liver could be demonstrated in five cases. The computer tomographic findings which, previously, could only be obtained by angiography, are described. The value of the method as a diagnostic procedure is discussed and its limitations compared with angiography are documented.