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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.

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.

Ziel war es, verschiedene Methoden der Beurteilung des Operationsergebnisses nach Isthmusstenosenkorrektur mit der MR-Tomographie auf ihre Genauigkeit hin zu prufen und morphometrischen Ergebnisse mit Funktionsparametern zu vergleichen. Methoden 54 Patienten (Alter 6–36 Jahre) wurden im postoperativen Langzeitverlauf einer kernspintomographischen Untersuchung unterzogen. Die morphometrische Quantifizierung erfolgte mit wachstumsabhangigen Normalwerte der Aorta und mit den Durchmessern der Aorta ascendens (AA), Aorta descendens (AD) und ihrem Mittelwert (MW). Als Funktionsparameter wurden Dopplerflussmessungen, ozillometrische Blutdruckgradienten und kernspintomographische Flussmessungen zum Vergleich herangezogen. Ergebnisse Bei Patienten mit operierten Isthmusstenosen fanden sich uberwiegend subnormale Durchmesser der AA (MW: 80% der Norm) und der AD (MW: 95% der Norm). Im Vergleich mit den Normalwerten war die mittlere Streuung (s y|x) der Durchmesser der AD bei den Patienten signifikant groser (2,6 vs. 1,5mm, p

This study investigated the value of fluorine-18 2'-deoxy-2-fluoro- D-glucose (FDG) imaging with a double-headed gamma camera operated in coincidence (hybrid PET) detection mode in patients with suspected spondylitis. Comparison was made with conventional nuclear medicine imaging modalities and magnetic resonance imaging (MRI). Sixteen patients with suspected spondylitis (nine male, seven female, mean age 59 years) prospectively underwent FDG hybrid PET (296 MBq) and MRI. For intra-individual comparison, the patients were also imaged with technetium-99m methylene diphosphonate (MDP) (555 MBq) ( n=13) and/or gallium-67 citrate (185 MBq) ( n=11). For FDG hybrid PET, two or three transverse scans were performed. Ratios of infected (target) to non-infected (background) (T/B) vertebral bodies were calculated. MR images were obtained of the region of interest. Patients found positive for spondylitis with MRI and/or FDG hybrid PET underwent surgical intervention and histological grading of the individual infected foci. Twelve out of 16 patients were found to be positive for spondylitis. Independent of the grade of infection and the location in the spine, all known infected vertebrae ( n=23, 9 thoracic, 12 lumbar, 2 sacral) were detected by FDG hybrid PET. T/B ratios higher than 1.45+/-0.05 (at 1 h p.i.) were indicative of infectious disease, whereas ratios below this value were found in cases of degenerative change. FDG hybrid PET was superior to MRI in patients who had a history of surgery and suffered from a high-grade infection in combination with paravertebral abscess formation ( n=2; further computed tomography was needed) and in those with low-grade spondylitis ( n=2, no oedema) or discitis ( n=2, mild oedema). False-positive 67Ga citrate images ( n=5: 2 spondylodiscitis, 1 aortitis, 1 pleuritis, 1 pulmonary tuberculosis) and 99mTc-MDP SPET ( n=4: 1 osteoporosis, 2 spondylodiscitis, 1 fracture) were equally well detected by FDG hybrid PET and MRI. No diagnostic problems were seen in the other patients ( n=5). In this study, FDG hybrid PET was superior to MRI, 67Ga citrate and (99m)Tc-MDP, especially in patients with low-grade spondylitis (as compared with MRI), adjacent soft tissue infections (as compared with 67Ga citrate) and advanced bone degeneration (as compared with 99mTc-MDP).

UNLABELLED Impact of different iodine concentrations on abdominal enhancement in biphasic multislice helical CT (MS-CT). PURPOSE To evaluate if different iodine concentrations of a contrast material (c.m.) have an impact on abdominal enhancement in MS-CT during the arterial (AP) and portal venous phase (PVP). MATERIALS AND METHODS 75 patients underwent biphasic CT of the abdomen. They were assigned to three equally sized groups. For all patients a non-ionic c.m. (iopromide, Ultravist, Schering AG, Berlin) with different iodine concentrations and a constant total iodine load of 37 g with an injection flow rate of 4 ml/s was used. The volume of the c.m. differed depending on the iodine concentrations: group 1 (123 ml of 300 mgl/ml); group 2 (112 ml of 335 mgl/ml); group 3 (100 ml of 370 mgl/ml). The scan delay was optimized by using a bolus tracking device. The groups were compared concerning their mean enhancement of aorta, spleen, pancreas, and liver in the AP and PVP. RESULTS The comparison of the three groups showed an improved enhancement in aorta, spleen, and pancreas during the AP by using the higher c.m. concentrations. In the PVP the c.m. enhancement of aorta, liver, spleen, and pancreas was independent of the administered c.m. concentration. CONCLUSION Higher iodine concentrations of c.m. have a positive impact on abdominal enhancement during the AP. The concentration has no influence on the enhancement during the PVP of abdominal MS-CT.

Summary Aim: In order to evaluate the diagnostic efficiency of arthroscintigraphy in suspected rotator cuff ruptures this new imaging procedure was performed 20 times in 17 patients with clinical signs of a rotator cuff lesion. The scintigraphic results were compared with sonography (n = 20), contrast arthrography (n = 20) and arthroscopy (n = 10) of the shoulder joint. Methods: After performing a standard bone scintigraphy with intravenous application of 300 MBq 99m-Tc-methylene diphosphonate (MDP) for landmarking of the shoulder region arthroscintigraphy was performed after an intraarticular injection of 99m-Tc microcolloid (ALBURES 400 μCi/5 ml). The application was performed either in direct combination with contrast arthrography (n = 10) or ultrasound conducted mixed with a local anesthetic (n = 10). Findings at arthroscopical surgery (n = 10) were used as the gold standard. Results: In case of complete rotator cuff rupture (n = 5), arthroscintigraphy and radiographic arthrography were identical in 5/5. In one patient with advanced degenerative alterations of the shoulder joint radiographic arthrography incorrectly showed a complete rupture which was not seen by arthroscintigraphy and endoscopy. In 3 patients with incomplete rupture, 2/3 results were consistant. A difference was seen in one patient with a rotator cuff, that has been already revised in the past and that suffered of capsulitis and calcification. Conclusion: Arthroscintigraphy is a sensitive technique for detection of rotator cuff ruptures. Because of the lower viscosity of the active compound, small ruptures can be easily detected, offering additional value over radiographic arthrography and ultrasound, especially for evaluation of incomplete cuff ruptures.

Die Diagnose einer glenohumeralen Instabilitat wird in den meisten Fallen schon durch die Anamnese und die klinische Symptomatik gestellt. Aufgabe der bildgebenden Verfahren ist es, Art und Ausmas der zugrundeliegenden Pathologie exakt zu dokumentieren und eine Entscheidungshilfe fur das therapeutische Vorgehen zu liefern. Konventionelle Rontgenaufnahmen in gut eingestellten Projektionen stellen unverandert die Grundlage jeder bildgebenden Diagnostik dar, wobei jedoch typische pathologische Befunde insbesondere am Kapsel-Band-Apparat dem radiologischen Nachweis entgehen. Mit der Nativ-CT gelingt der eindeutige Nachweis von knochernen Verletzungen am Pfannenrand und am Humeruskopf. Als etabliertes Verfahren zur Beurteilung des kapsulolabralen Komplexes gilt die CT-Arthrographie. Nachteile sind die Gelenkpunktion und der vermehrte Zeitaufwand. Als Alternative bietet sich die Magnetresonanztomographie an. Sie liefert als nicht-invasive Untersuchung mit hohem Gewebekontrast in beliebigen Schnittebenen in der Diagnostik des Labrums und der Gelenkkapsel eine ahnlich hohe Treffsicherheit, kann jedoch bei Formvarianten und fehlendem Gelenkergus diagnostische Schwierigkeiten aufwerfen. Der Stellenwert der verschiedenen Verfahren wird diskutiert.

Bilateral apparently bony structures of different forms and sizes located in the inferior and superior ventral parts of the sacroiliac joints were observed on axial CT images of the pelvic region of juvenile patients. No other pathological changes were noted in the sacroiliac joints of these individuals. In one patient the bony structures could also be seen on a conventional plain radiograph. We also examined 3 juvenile autopsy specimens of this joint using radiology, CT, macroscopical evaluation and histology. In two of them, structures could be detected on the CT scans which were similar to those observed in the young patients. Macroscopic investigations revealed the structures to be secondary ossification centres located in the articular cartilage of the lateral part of the os sacrum at the levels of the first and third sacral segments. According to older anatomical literature, these epiphysial ossification centres contribute to the auricular surface of the lateral part of the os sacrum and the free lateral surface of the inferior sacral parts. They can be observed between the ages of 12 and 25 years and begin to synostose with the lateral part around the age of 18 years. In macerated juvenile specimens of the bony pelvis, free ossicles were not detectable in the region of the sacroiliac joints. Histological peculiarities of the ossification process observed are discussed. These physiologically occurring ossification centres are to be differentiated from pathological alterations appearing as bony or bone-like structures on CT scans.

Measurements of bone density were carried out in 25 patients on dialysis for terminal renal insufficiency, using quantitative computed tomography (QCT) and dual-energy X-ray absorptiometry (DXA). Unlike in subjects with normal kidneys, there was no significant correlation between these methods in this series. Ten patients showed an increase in bone density of the vertebral spongiosa on QCT measurements, which was interpreted as due to osteosclerotic bone changes in renal osteopathy. QCT showed advantages over DXA in demonstrating these changes.

Between the ages of 12 and 18 years apophyseal elements appear within the SI joints which fuse subsequently with the sacrum. These apophyses could be demonstrated during two autopsies on juveniles and were seen in 7 CT examinations of patients between the ages of 15 and 19. On CT they appeared as narrow, round or band-like opacities situated on the ventral aspect of the joint. The differentiation of these normal findings from pathological changes within the SI joints is discussed.

Wir berichten uber einen seltenen Fall einer primaren muskularen Hydatidose am Musculus biceps femoris bei einem jungen Mann aus dem Irak. Der Patient stellte sich mit dem Verdacht eines Weichteiltumors unklarer Genese am rechten Oberschenkel in der Orthopadischen Ambulanz unserer Klinik vor. Eine zuvor angefertigte MRT zeigte das charakteristische Bild einer Hydatidose an beschriebener Lokalisation mit typischem zystischen Befund mit Zysteninhalt (sogenannte „cyst within a cyst“).Aufgrund dieser pathognomonischen MR-Morphologie wurde eine initial vorgesehene Probeentnahme nicht durchgefuhrt, um eine hamatogene Streuung zu vermeiden. Die alternativ erfolgte serologische Abklarung bestatigte einen hohen Antikorpertiter gegen Echinococcus granulosus. Daraufhin wurde die elektive operative „in toto“ Entfernung des Befundes geplant. Perioperativ erfolgte eine antibiotische Prophylaxe mit Albendazole. Unmittelbar praoperativ kam es zu einer spontanen Ruptur der Zyste mit einer ausgepragten lokalen Entzundungsreaktion der Oberschenkelweichteile, die in einer zusatzlichen MRT dargestellt wurde. Trotz Ruptur erfolgte die operative Ausraumung der Muskulatur mit Entfernung der Zystenhulle. Die histologische Aufarbeitung des OP-Praparates zeigte neben einer Entzundungsreaktion eine Cuticula nach Art einer Hydatidose von Echinococcus granulosus. Lernziele: Das vorliegende Bildmaterial zeigt die Moglichkeit der spezifischen Zuordnung des Befundes aufgrund seiner typischen Bildmorphologie, trotz der ungewohnlichen Lokalisation. Hierdurch konnte in diesem Fall eine praoperative Punktion mit der Gefahr einer hamatogenen Streuung und moglicher Anaphylaxie vermieden werden. Die zusatzlich angefertigte MRT nach spontaner Ruptur dokumentiert ferner in beeindruckender Weise die entzundliche Weichteilreaktion. Korrespondierender Autor: Psychogios MN Uniklinikum Gottingen, Diagnostische Radiologie, Zur Hohen Warte 19, 37077 Gottingen E-Mail: mn.psyc@gmail.com

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.

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.

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.

To evaluate the usefulness of a computer-aided detection (CAD) system in full-field digital mammography in correlation to tumor histology.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.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.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.

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.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).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 %.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.

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.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.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 nodules2 mm, respectively.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.

This study determined the diagnostic performance of ECG-gated MSCT in comparison with conventional MSCT.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.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, p0.05). 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.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.

To evaluate the diagnostic value of a higher concentrated contrast medium (gadobutrol) for contrast-enhanced MRA of the hepatic arteries and portovenous system.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.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.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.

To investigate the value of different postprocessing algorithms for multislice spiral CT (MSCT) in diagnosing acute pulmonary embolism.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.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).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.

To increase the quality of internal and external interactions (patients, clinical colleagues, technicians, radiologists) in a department of radiology.Accompanied by a well-experienced adviser workshops have been performed dealing with different topics like "contact to patients," "performance of the radiological report and interaction with the referring colleague" or "research and teaching." A catalogue of different actions was defined to reduce hindrances within the internal and external work-flow.A total number of 53 actions was defined and related to different persons who were responsible for the realisation of the measures within a time interval. Six months after starting the quality management 46 (86%) of the defined actions were realised successfully, and another 4 (8%) measures were still running. There was a moderate increase of satisfaction of the patients and clinical colleagues considering the waiting time.A quality management in a radiological department allows an optimisation of the internal and external interactions. However, the guidance of a well-experienced adviser is as essential as the continuous control of successful finished measures.

Our goal was to compare digital magnification mammograms with images zoomed from the digital contact mammogram in patients with microcalcifications.Fifty-five patients with 57 microcalcification clusters were evaluated with a FFDM system (Senographe 2000D, GE). In addition to a digital contact mammogram, a digital direct magnification mammogram (factor 1.8 [MAG1.8]) and an image zoomed from the contact mammogram with a magnification factor of 1.8 [ZOOM1.8] were obtained in each patient. The image quality (perfect = 5 points to inadequate = 1 point) and the characterization of microcalcifications (BI-RADS 2-5) were evaluated by 4 readers. The results were compared to histopathologic findings in 35 patients (37 lesions) and follow-up in 20 patients.Histopathology revealed 16 benign and 21 malignant lesions. 20 patients had benign changes verified by long-term follow-up. Image quality of direct magnification FFDM was assessed superior (4.44 points) to zoomed images (4.14 points). Sensitivity was superior for direct magnification (97.5%) in comparison to the zoomed images (96.3%). However, specificity (MAG1.8: 34.3%, ZOOM1.8: 40%), PPV (MAG1.8: 47.5%, ZOOM1.8: 49.8%) and accuracy (MAG1.8: 58.1%, ZOOM1.8: 61.2%) were better with zooming technique. Deviation steps from best BI-RADS assessment were 0.45 for MAG1.8 and 0.44 for ZOOM1.8.In patients with mammographic microcalcifications, monitor zooming of the digital contact mammogram is equivalent to direct magnification FFDM. Therefore, monitor zooming allows a reduction of the radiation exposure and an optimization of the work-flow.

The establishment of digital mammography systems constitutes a slow process, the reason for this being the general need of particular image quality in mammography. This article provides an overview of the physical basis of digital mammography with high image quality and dose as low as reasonably achievable. The trade-off of high contrast resolution and effective quantum efficiency of the imaging system on the one hand, and the demand of high spatial resolution or very small pixel size on the other hand is discussed. The actual status of the available digital detector technology for mammography is described. The digital systems presently available are superior to conventional screen-film mammographic systems with respect to contrast resolution. An outlook on possible further developments in the field of digital mammography is presented.

To compare the results of different methods for postoperative assessment after coarctation repair by magnetic resonance imaging and to evaluate their reliability. The morphometric results are contrasted to functional parameters of CW Doppler, oscillometric pressure gradient and flow quantification in VEC-MRI.54 patients (age: 6 to 36 years) were assessed by MRI 3 to 31 years after coarctation repair. The aortic diameters were compared to growth-dependent normal values and to the diameter of the ascending (AA) and descending aorta (DA), and their mean values (MV).Patients after coarctation repair had mostly subnormal diameters of AA (mean value: 80% of normal) and AD (95% of normal). Compared to the control group, mean dispersion of AD diameters was significantly larger in the patient group (2.6 vs. 1.5 mm, p0.001). Degree of stenosis varied with the method. It was similar when using normal values and the diameter for DA, but dispersion was smaller when normal values were used. Correlation of the functional parameter to the degree of stenosis was weak. The highest correlation (r = 0.78) was reached when using normal values as the reference with mean cross-sectional velocity from VEC-MRI.The use of normal values as the reference for quantification of residual coarctation is more reliable than common methods. Since only one measurement is needed, it seems to be less susceptible to errors and more practical. MRI offers not only a tool for accurate morphologic assessment, but with VEC-MRI it is also possible to obtain a functional parameter which is superior to oscillometric pressure gradient and CW Doppler.

As a consequence of technical improvements and an increased number of investigations in asymptomatic patients, more and more suspicious lesions are being detected in mammography. These lesions can be evaluated using different biopsy techniques. In comparison to open biopsy, stereotactic methods require less costs and time, and reduce morbidity. The introduction of the vacuum core biopsy method allowed the excision of suspicious areas through a single needle insertion. In the current literature, however, the indications for vacuum core biopsy are being discussed controversely. This article includes an introduction of this specific technique, a presentation of the BI-RADS (Breast Imaging Reporting and Data System) categories and an overview of the literature of the indications for use of the vacuum system. The "pros and cons" of vacuum core biopsy will be discussed in comparison with the alternative biopsy methods.

When imaging the portal vascular system colour-coded sonography and CT angiography are used as an alternative to intraarterial DSA. Today fast CE 3D-MRA is the imaging modality of choice in the diagnostic of patients with portal hypertension. It enables a clear picture of the portalvenous vascular system and portalsytemic shunts. Statements regarding velocity and direction of blood flow can be made with additional use of TOF and PC techniques. CE-3D MRA can be used preoperatively before liver transplantation or shunt surgery. In the follow-up of interventional or surgical procedures exact statements concerning haemodynamically significant pathologies e.g. vascular thromboses, stenoses and occlusions can be made. Patient consent is symplify and the numbers of complications can be reduced as well as duration of surgery minimized applying this technique.

It is the aim of this study to investigate the efficiency of multislice helical CT for the diagnosis of cervical spine fractures. The advantages of this technique are demonstrated by case reports.The entire cervical spine or selected vertebral bodies of 66 patients with cervical spine fractures known from preceding plain films were scanned with a multislice helical CT. The CT-scans were obtained with a slice thickness of 1.25 mm and with two different pitches (0.75 or 1.5) and table speeds (3.75 or 7.5 mm/rot.). Additionally, sagittal and coronal reformations were performed.The mean scan-time for the cervical spine was 13 seconds. High quality sagittal and coronal reformations were obtained from axial images within a few minutes. Fractures of the dens (n = 17) and of the vertebral body of C3-C7 (n = 12) occurred predominantly.Multislice helical CT is an effective tool to diagnose fractures of the cervical spine rapidly and exactly.

Impact of different iodine concentrations on abdominal enhancement in biphasic multislice helical CT (MS-CT).To evaluate if different iodine concentrations of a contrast material (c.m.) have an impact on abdominal enhancement in MS-CT during the arterial (AP) and portal venous phase (PVP).75 patients underwent biphasic CT of the abdomen. They were assigned to three equally sized groups. For all patients a non-ionic c.m. (iopromide, Ultravist, Schering AG, Berlin) with different iodine concentrations and a constant total iodine load of 37 g with an injection flow rate of 4 ml/s was used. The volume of the c.m. differed depending on the iodine concentrations: group 1 (123 ml of 300 mgl/ml); group 2 (112 ml of 335 mgl/ml); group 3 (100 ml of 370 mgl/ml). The scan delay was optimized by using a bolus tracking device. The groups were compared concerning their mean enhancement of aorta, spleen, pancreas, and liver in the AP and PVP.The comparison of the three groups showed an improved enhancement in aorta, spleen, and pancreas during the AP by using the higher c.m. concentrations. In the PVP the c.m. enhancement of aorta, liver, spleen, and pancreas was independent of the administered c.m. concentration.Higher iodine concentrations of c.m. have a positive impact on abdominal enhancement during the AP. The concentration has no influence on the enhancement during the PVP of abdominal MS-CT.

To evaluate the detection rate of vascular stenosis in contrast-enhanced 3D MR angiography using a flow phantom.The examinations were performed on a 1.5 T whole body imaging system (Magnetom Symphony/Quantum) with 30 mT/m gradient field strength using a body-phased-array coil. Different 3D sequences (TR/TE/FA5 ms/2 ms/25 degrees ) with slice thicknesses ranging from 0.67 to 1.25 mm were applied. A gelantine-filled plastic cylinder with PVC tubes of 8 mm diameter was used as a vascular phantom. The tubes had concentric and excentric stenoses (50 - 90 %) of different lengths. For the detection of different vessel diameters another phantom with 0.3 - 8 mm silicon tubes was used. Both systems were flushed with a solution of Gd-DTPA (0.15 mmol/l) and saline at flow rates from 50 to 200 cm/s. The phantoms were positioned 0 degrees, 45 degrees, and 90 degrees towards the z-axis.The degree of stenosis was under- and overestimated in less than 10 %. The sequence with the highest spatial resolution provided the best results. Detection and evaluation of tubes/= 2 mm proved to be reliable.Contrast-enhanced 3D MR angiography provides an almost exact evaluation of the degree of stenosis in the phantom study. Evaluation of vessel diameters2 mm is not possible.

Evaluation of stereotactic vacuum core biopsy of clustered microcalcifications categorized as BI-RADS 3.86 patients with microcalcifications BI-RADS 3 (probably benign,3% malignant) underwent a stereotactic vacuum core biopsy (Mammotome, Fa. Ethicon Endo-Surgery Breast Care) using a digital stereotactic unit (Mammotest, Fa. Fischer Imaging). The removal of the calcifications was judged by two radiologists in consensus and classified as complete (100%), major (55-99%) or incomplete (50%).4/86 patients could not be evaluated by vacuum core biopsy due to the localization of the microcalcifications close to the skin or lack of detection. In 40/82 cases a complete, in 38/82 a major, and in 4/82 a incomplete removal was achieved. Histology revealed 67 cases of fibrocystic changes, 4 papillomas, 4 fibroadenomas, 4 cases of atypical ductal hyperplasia (ADH), and 3 ductal carcinomas in situ (DCIS), one of these with a minimal-invasive tumor component. Patient with ADH were advised to undergo surgical biopsy. Histology revealed complete removal. 7 patients had complications or side-effects.Percutaneous vacuum core biopsy is a reliable minimal-invasive diagnostic method to come to the final diagnosis in patients with clustered microcalcifications categorized BI-RADS 3. However, if malignancy is proven (about 4% of our cases) an open biopsy is necessary.

To determine the value of multi-slice CT for the diagnosis of acute pulmonary embolism and an underlying venous thrombosis.70 patients with clinically suspected acute pulmonary embolism were examined. Using multi-slice CT a combined examination of the pulmonary arteries and the veins of the lower limb, pelvis and abdomen was performed. Only one single bolus of 150 ml iopromid 300 was injected into a cubital vein with a flow of 4 ml/s. First, the pulmonary arteries were scanned with a slice thickness of 2.5 mm and a pitch of 1.5. On arrival of the contrast medium at the popliteal veins, indicated by bolus trakking, the veins of the lower limbs up to the end of the inferior vena cava were imaged using a slice thickness of 3.75 mm and a pitch of 1.5. The results could be compared with a ventilation-perfusion scan in 48 cases, with a Doppler ultrasound examination in 46 cases, and with a venography in 10 cases. Furthermore, the image quality of all arterial and venous regions was subjectively assessed.In all patients who underwent multi-slice CT the pulmonary arteries as well as the veins of the lower half of the body could be recorded completely. Regarding the pulmonary arteries the image quality showed excellent results for the central and segmental arteries. The region up to the 3rd division in subsegmental branches could be sufficiently judged. More peripherally, a diagnostic assessment was not possible. The image quality of the veins was excellent in all sections, except the calf, where a reliable diagnosis could not be made. The comparison with the other techniques confirmed the superiority of multi-slice CT concerning the central and segmental pulmonary arteries and the veins from the popliteal vein to the inferior vena cava. In contrast, peripheral pulmonary emboli can be detected more certainly in ventilation/perfusion scans. The veins of the calf can be evaluated more reliably with venography.Multi-slice CT proved to be an outstanding tool in the diagnosis of acute pulmonary embolism. The clinically suspected disease and a causing venous thrombosis can be detected in a fast and reliable way. At present, multi-slice CT is not suitable for the recognition of peripheral emboli. However, expected technical developments hold promise for future improvements.

To evaluate the digital technique for screening mammography various experimental studies and clinical examinations were performed by using direct full-field digital mammography (FFDM). The findings concerning the detectability and characterization of microcalcifications and soft tissue masses as well as the radiation exposure were compared to the state-of-the-art conventional screen-film mammography (SFM). The results of these studies revealed a high performance of the digital images, which are at least equivalent to the conventional images, whereas digital spot views were significantly superior to conventional ones particularly in the detection of microcalcifications. This was especially true, when the potential of post-processing was used. In addition, the sensitivity of FFDM should be increased, if computer-aided-diagnosis (CAD) is available. Furthermore, the patient radiation dose can be significantly reduced. Additional advantages are quick and easy handling, efficient data transfer and digital archiving. Thus, FFDM will become an important tool in screening mammography.

The study compares contrast-detail and microcalcification detectability of a full-field digital mammography (FFDM) to a state-of-the-art conventional screen-film mammography (SFM) by using different doses in the digital system.The investigations were performed with an FFDM (Senographe 2000 D, GEMS) and an SFM system (Senographe DMR, GEMS) using a contrast-detail mammography phantom (CDMAM) and an anthropomorphic breast phantom with superimposed microcalcifications. The digital detector was exposed with standard dose of SFM and with a dose reduction of up to 75%. Contrast-detail curves and correct observation ratio (COR) were performed for the CDMAM phantom. ROC analysis with a confidence level ranging from 1 to 5 was done with the results of the anthropomorphic phantom.Digital mammography with the same dose revealed at least an equivalent or even higher detectability rate than conventional mammography, COR could be increased at about 10-25%. The ROC analysis yielded better results for the FFDM system. The same lesion detectability in digital mammography as in the conventional method was reached at a dose reduction of about 25%, concerning spot views even at higher reduction. Dose reduction in the anthropomorphic phantom resulted in a linear loss of detectability. The same detectability as in conventional mammography was reached, however, by a dose reduction of about 50%.The results suggest that FFDM is at least equivalent to or--as far as spot views are concerned--superior to conventional SFM concerning the detectability of simulated lesions. Thus, a potential of dose reduction is suggested.

Comparison of radiation exposure between a digital amorphous silicon and a screen-film based mammography system. Evaluation of a possible potential of full-field digital mammography in order to decrease the radiation dose.The average glandular dose for phantom thicknesses from 30 to 60 mm was calculated from experimentally determined entrance surface air kerma for a digital and a conventional mammography system. The effect of reducing the detector dose and of changing the radiation quality on radiation exposure and on image quality were investigated.By using the delivered settings of the automatic exposure control (AEC) devices, both mammographic systems needed nearly the same doses. Regulations and guidelines on radiation doses were complied. With the digital system, a reduction of radiation exposure of up to 40% by using a higher radiation quality and decreasing slightly the detector dose without loss of diagnostic image quality, might be possible.The potential of full-field digital mammography for radiation dose reduction, as shown in the present phantom study, needs however, a careful examination under clinical conditions.

The aim of this study is to determine the optimal scan parameters for the evaluation of experimental vascular stenoses with a multislice-helical CT.A vascular phantom consisting of four tubes with an inner diameter of 8 mm and with experimental stenoses of 50%, 75% and 90% was scanned in different tube orientations using a multislice-CT scanner (LightSpeed QX/i, GE, Milwaukee, USA). Examinations were performed with increasing collimations (1.25-5 mm), tube currents (100-300 mA) and two different table speeds (0.75 HQ mode and 1.5 HS mode).The most exact measurements were obtained in tubes angulated parallel to the scan direction with a collimation of 2.5 mm in the HQ mode (7.5 mm/rot.). An almost equivalent accuracy was obtained in the HS mode (15 mm/rot.) with a collimation of 2.5 mm when higher tube currents (300 mA) were employed. The degree of stenoses was overestimated when the tube was angulated perpendicular to the z-axis.Multislice-CT provides a good detection rate of vascular stenoses especially at 0 degree and also at 45 degrees angulation in the HQ mode. The use of the HS mode with higher tube currents allows scanning of longer distances with almost identical accuracy.

The study compares direct full-field digital mammography (FFDM) to the state-of-the-art conventional screen-film mammography (SFM) concerning the detectability of simulated microcalcifications.The investigations were performed with a FFDM system (Senographe 2000D, GEMS) and a SFM system (Senographe DMR, GEMS, Fuji UM MA film with Fuji UM MAMMO FINE screen). An anthropomorphic breast phantom with superimposed microcalcifications (50-200 microns) was used to evaluate the detectability of microcalcifications with a confidence level ranging from 1 to 5. Contact mammograms and magnification spot views (m = 1.8) of the FFDM and SFM systems were compared. A receiver operating characteristic (ROC) analysis was performed by three well-experienced readers.The ROC analysis revealed a higher performance of the digital images compared to the conventional screen-film mammograms. The area under the ROC-curve (Az) in the digital contact mammograms was 0.68 versus 0.63 in the conventional technique. The results were not significantly different. In digital spot views, Az was 0.79 versus 0.70 in the conventional spot views.The results suggest that FFDM is at least equivalent or--as far as spot views are concerned--may be superior to conventional SFM in the detection of microcalcifications.

The technical conditions, the optimized scanning protocols and the facilities of virtual endoscopy (VE) are presented in an overview.Phantom studies showed that, for a single-row-detector helical CT, collimation of 3.0 mm combined with pitch of 1.5 provided an optimal compromise between image quality and the scan duration per breath-hold. A multi-row-detector helical CT requires only a fraction of the scanning time. This is especially important for patients with dyspnea.The threshold-dependent virtual endoscopic surface rendering is a reliable and rapidly practicable reconstruction algorithm for the imaging of the upper airway.The VE technique is suitable for the imaging of space-occupying tumors and restricted stenoses. With VE follow-up examinations can be performed non-invasively and interventional procedures can be prepared in an optimal way. Because of the computed tomographic data acquisition the structure of the mucosa is not assessable and there is no opportunity to obtain a biopsy specimen.

The purpose of this phantom study was to evaluate the visualization of vascular stents by using contrast-enhanced (CE) 3D MR angiography (MRA).The measurements were performed on a Magnetom Vision operating at 1.5 T with 25 mT/m gradients by using a head coil; a 3D FISP sequence (TR/TE/FA 4.6 ms/1.8 ms/30 degrees) was used. A phantom was designed with a length of 20 cm and consisted of a plastic cylinder filled with hydrogel. Tubes were used to install 7 different stents (Strecker, Boston Scientific; Cragg, Mintec; Wall, Schneider; Memotherm, Angiomed; St-Come, Trigon-MTS; Sinus, Optimed; Palmaz, JohnsonJohnson) with different metal components. The tubes were perfused with a solution of water and Gd-DTPA. Four radiologists evaluated the image quality. The measurements of the endoluminal stent diameters were compared with the findings obtained by digital subtraction angiography. The signal intensities were measured before (inflow), within (stent) and after (outflow) the different stent types.The endoluminal diameter of the Cragg stent and the strecker graft were easily detectable. The signal loss within the lumen of the Wall stent was approx. 10% in relation to the inflow and outflow measurements. The result was an only slightly reduced image quality. The other grafts (St-Come, Sinus, Palmaz, Memotherm) showed significant signal losses ranging from 65% to 96%. A correct diagnosis was not possible within these graft lumina.Contrast-enhanced MR angiography can be used to evaluate vascular stents. A prerequisite is the application of particular commercially available grafts.

The aim of this study was to evaluate the roles of 67Ga-citrate and 99Tcm-methylene diphosphonate (99Tcm-MDP) planar and single photon emission tomographic (SPET) imaging in patients with vertebral osteomyelitis. Thirty patients (22 females, 8 males) aged 62.7 +/- 16.4 years (mean +/- s) were enrolled prospectively between May 1995 and May 1998. The patients had been on antibiotics for 7 +/- 4 weeks prior to the study. Histology was available for all but nine patients with mild infections, who were evaluated by a combination of magnetic resonance imaging (MRI), clinical and laboratory tests. 67Ga-citrate (185 MBq) and three-phase bone (555 MBq 99Tcm-MDP) planar and SPET imaging were performed in all patients, together with MRI as a comparison. In total, 67 infectious foci were detected. Based on histology, there were four cases of severe, 13 cases of moderate and four cases of mild osteomyelitis; nine mild infections were also classified by the combination of MRI, clinical and laboratory results. Combined MRI and 67Ga-citrate SPET correctly classified all patients; MRI detected all 67 infectious foci, whereas 67Ga-citrate SPET identified 54 only. False-negative results were seen with all other modalities, especially in cases of mild and moderate infection. 67Ga-citrate SPET identified unsuspected cases of endocarditis (n = 2), paravertebral abscess (n = 1), subaxillary soft tissue abscess (n = 1) and rib osteomyelitis (n = 1). For 67Ga-citrate SPET, the target-to-background ratio was 2.24 +/- 0.31, 1.76 +/- 0.07 and 1.30 +/- 0.18 for severe, moderate and mild osteomyelitis, respectively. Significant differences were noted between severe and moderate infection (P = 0.0051) and between severe and mild infection (P < 0.0001); that between moderate and mild infection was non-significant. For 99Tcm-MDP planar and SPET imaging, and for planar 67Ga-citrate imaging, there was no correlation with severity. We conclude that 67Ga-citrate SPET is able to identify vertebral osteomyelitis and detect additional sites of infection. It can also aid in determining the severity of infection and, potentially, the response to therapy.

To compare digital X-ray, CT, and MRI in the evaluation of ligamentous and osseous lesions in upper cervical spine specimens after artificial craniocervical injury with the findings of macroscopic preparation.A rotation trauma of defined severity was applied to 19 human corpses. After dissection of the neck specimens, digital X-ray (DIMA Soft P41, Feinfocus), conventional and helical CT (CTi, High Speed, GE, collimation 1 mm; pitch 1.0), and MRI were performed from the skull base to C3. The findings were correlated with the macroscopic results of preparation. MR (Magnetom Vision, Siemens) imaging was obtained with a 1.5 T system using 2D- and 3D-sequences.Preparation revealed 6 fractures of the vertebral bodies, 5 fractures of the dens axis, 1 fracture of the arcus anterior of the atlas, 4 osseous flakes at the occipital condylus, and 6 lesions of the alar ligaments. Digital radiography showed all fractures and 4 osseous flakes at the occipital condylus. With conventional and helical CT, all fractures and all ruptured alar ligaments could be detected. 2D MRI depicted 9 of the fractures and 3D MRI showed fractures. With 2D MRI, 2 of the 4 osseous flakes at the condylus could be detected and with 3D MRI one occipital condylus fracture could be depicted. Ligamentous injuries were visualized by 2D MRI in 2 of 6 cases and by 3D MRI in one case.In post-mortem studies, CT was superior to MRI in the visualization of osseous and ligamentous injuries after trauma of the upper cervical spine. However, these results are not transferable to patients with rotation injury in general.

In a clinical study, the feasibility of using a mammography workstation for the display and interpretation of digital mammography images was evaluated and the results were compared with the corresponding laser film hard copies.Digital phosphorous plate radiographs of the entire breast were obtained in 30 patients using a direct magnification mammography system. The images were displayed for interpretation on the computer monitor of a dedicated mammography workstation and also presented as laser film hard copies on a film view box for comparison. The images were evaluated with respect to the image handling, the image quality and the visualization of relevant structures by 3 readers.Handling and contrast of the monitor displayed images were found to be superior compared with the film hard copies. Image noise was found in some cases but did not compromise the interpretation of the monitor images. The visualization of relevant structures was equal with both modalities. Altogether, image interpretation with the mammography workstation was considered to be easy, quick and confident.Computer-assisted visualization and interpretation of digital mammography images using a dedicated workstation can be performed with sufficiently high diagnostic accuracy.

Acute diseases of the central arteries require an immediate investigation. An efficient, fast and reliable diagnosis is necessary because of the high mortality, if the patient remains untreated. These requirements are perfectly fulfilled by the new CT-techniques.Suspected aortic diseases were examined with a new multi-slice helical CT. The thoracic or the abdominal aorta as well as the entire vascular tree from the supra-aortic branches to the inguinal arteries were investigated with different CT protocols. The slice-thickness and the scan mode were changed while the total examination time was kept constant for the first two groups. In the third group a monophasic examination was compared to a biphasic one.In the diagnosis of acute aortic diseases multi-slice helical CT proved to be a fast and reliable method with all scan protocols. The objective measurements of contrast homogeneity and image quality were comparable in the first two groups. The monophasic contrast medium injection protocol was superior to the biphasic administration mode.Multi-slice helical CT appears to be a very effective approach for the diagnosis of acute aortic diseases and seems to be the new gold standard.

Scan protocol optimization and value of a multi-row-detector helical CT (MS-CT) in comparison to a single-row-detector spiral CT (SS-CT) for imaging of focal liver lesions.The ability of a MS-CT with different scan parameters (slice thickness, scan mode, table-speed, reconstruction interval) for the detection of low-contrast objects was evaluated with a liver phantom and compared to a SS-CT. The clinical value (detection and characterization) of MS-CT with various slice thicknesses (3.75, 5, 7.5 mm) was compared intraindividually in 20 patients with a total of 43 benign and malignant lesions.In the experimental study the MS-CT reached the same detection rates for low-contrast objects despite a three-times faster scan-time compared to a SS-CT. The slice thicknesses of 3.75 and 5 mm proved to be optimal and were superior to a thickness of 7.5 mm for the detection and characterization of liver lesions. A distinct separation between arterial and portal venous phase was achieved by this protocol.The MS-CT allows a reliable acquisition of the entire liver parenchyma in defined perfusion phases. It improves the detection and characterization of focal liver lesions with optimized scan parameters with a significantly faster scan time than with the SS-CT.

Presentation and evaluation of slice sensitivity profile and pixel noise of multi-slice CT in comparison to single-slice CT.Slice sensitivity profiles and pixel noise of a multi-slice CT equipped with a 2D matrix detector array and of a single-slice CT were evaluated in phantom studies.For the single-slice CT the width of the slice sensitivity profiles increased with increasing pitch. In spite of a much higher table speed the slice sensitivity profiles of multi-slice CT were narrower and did not increase with higher pitch. Noise in single-slice CT was independent of pitch. For multi-slice CT noise increased with higher pitch and for the higher pitch decreased slightly with higher detector row collimation.Multi-slice CT provides superior z-resolution and higher volume coverage speed. These qualities fulfill one of the prerequisites for improvement of 3D postprocessing.