[MRI of the prostate]. / MRT der Prostata.

New clinical and technological advances in the field of magnetic resonance imaging (MRI) and targeted image-guided biopsy techniques have significantly improved the detection, localization and staging as well as active surveillance of prostate cancer in recent years. Multiparametric MRI (mpMRI) is currently the main imaging technique for the detection, characterization and diagnostics of metastasizing prostate cancer and is of high diagnostic importance for local staging within the framework of the detection of prostate cancer.

Shear wave elastography of the testes in a healthy study collective - Differences in standard values between ARFI and VTIQ techniques.

INTRODUCTION: Shear wave elastography (SWE) is a recent technique in the assessment of tissue elasticity. Different elastography techniques have been described over the years.Acoustic Radiation Force Impulse Imaging (ARFI) uses mechanical excitation of tissue to create detectable shear waves, a higher shear wave velocity being associated with an increased tissue stiffness.The Virtual Touch Tissue Imaging Quantification (VTIQ) method uses a mechanical push pulse as well, additionally creating a colour-coded map, in which tissue stiffness can be measured within a stored map on the ultrasound device after measurement.ARFI has been used in determining standard values in testes of a healthy study collective, VTIQ has already been used in the evaluation of unclear scrotal masses.Both techniques allow an operator-independent examination without application of mechanical pressure. The aim of this study was to determine whether there is a statistically significant difference between shear wave velocity values of both techniques in a healthy collective. MATERIAL AND METHODS: Twenty patients without known testicular pathology underwent standard B-mode sonography and additional shear wave elastography in the ARFI mode as well as the VTIQ technique of both testes using the Siemens Acuson S2000™ and S3000™ ultrasound devices (Siemens HealthCare, Erlangen, Germany).Measurements of shear wave velocity were performed in the upper pole, the central portion and the lower pole separately for each testis. Values were described in m/s.Statistical evaluation was performed using paired t-test analysis. RESULTS: We measured a mean shear wave velocity of 0.81 m/s using ARFI and 1.07 m/s with VTIQ.Shear wave velocities determined by VTIQ were all significantly higher than values gained in the ARFI mode. (p < 0.001 to p = 0.007). Values were between 0.22 and 0.29 m/s higher, when the examination was performed using VTIQ. CONCLUSION: ARFI and VTIQ elastography modes both proved to be feasible techniques in the assessment of testicular tissue elasticity. Consideration of higher values for VTIQ is important, when different elastography measurement results are compared, especially for the application of devices in a clinical setting, e.g. in the work-up of scrotal masses.A calculable factor for a comparison between both devices is desirable, but to be further assessed in largerstudies.

Three-dimensional vs. two-dimensional shear-wave elastography of the testes - preliminary study on a healthy collective.

INTRODUCTION: Shear wave elastography (SWE) and its derivative Supersonic Shear Imaging (SSI) are newer techniques for the determination of tissue elasticity by measuring the velocity of generated shear waves (SWV), which correlates positively with tissue stiffness.The techniques are integrated into many modern ultrasound systems and have been examined in the evaluation of viscoelastic properties of different organ systems. Two-dimensional shear wave elastography (2D SWE) of the testes has been found to be a useful tool in recent studies which included the determination of standard values in healthy volunteers. Three-dimensional shear wave elastography (3D SWE) is the latest development in elastography and is made possible by generation of a multiplanar three-dimensional map via volumetric acquisition with a special ultrasound transducer. This technique allows the assessment of tissue elasticity in a three-dimensional, fully accessible organ map.The aim of this preliminary study was to both evaluate the feasibility of 3D SWE and to compare 2D and 3D SWE standard values in the testes of healthy subjects. MATERIAL AND METHODS: We examined the testes of healthy male volunteers (n = 32) with a mean age of 51.06±17.75 years (range 25-77 years) by B-mode ultrasound, 2D and 3D SWE techniques in September of 2016. Volunteers with a history of testicular pathologies were excluded. For all imaging procedures the SL15-4 linear transducer (bandwidth 4-15 MHz) as well as the SLV16-4 volumetric probe (bandwidth 4-16 MHz) of the Aixplorer® ultrasound device (SuperSonic Imagine, Aix-en-Provence, France) were used. Seven regions of interest (ROI, Q-Box®) within the testes were evaluated for SWV using both procedures. SWV values were described in m/s. Results were statistically evaluated using univariateanalysis. RESULTS: Mean SWV values were 1.05 m/s for the 2D SWE and 1.12 m/s for the 3D SWE.Comparisons of local areas delivered no statistically significant differences (p = 0.11 to p = 0.66), except for the region in the central portion in the superior part of the coronal plane (p = 0.03). Testicular volume was significanty higher by a mean of 1.72 ml when measured with 3D SWE (p = 0.001). CONCLUSION: 3D SWE proved to be a feasible diagnostic tool in the assessment of testicular tissue, providing the examiner with a fully accessible three-dimensional map in a multiplanar or multislice view. With this technique a more precise testicular imaging - especially if combined with the display of tissue stiffness in SWE - is available and therefore could improve the diagnostic work-up of scrotal masses or the routine investigation of infertile men. Further studies for a better understanding in the context of various testicular pathologies will be required.

Differences of standard values of Supersonic shear imaging and ARFI technique - in vivo study of testicular tissue.

PURPOSE: To investigate the difference of standard values of Supersonic shear imaging (SSI) and Acoustic Radiation Force Impulse (ARFI) technique in the evaluation of testicular tissue stiffness in vivo. MATERIALS AND METHODS: 58 healthy male testes were examined using B-mode sonography and ARFI and SSI. B-mode sonography was performed in order to scan the testis for pathologies followed by performance of real-time elastography in three predefined areas (upper pole, central portion and lower pole) using the SuperSonic® Aixplorer ultrasound device (SuperSonic Imagine, Aix-en-Provence, France). Afterwards a second assessment of the same testicular regions by elastography followed using the ARFI technique of the Siemens Acuson 2000™ ultrasound device (Siemens Health Care, Germany). Values of shear wave velocity were described in m/s. Parameters of elastography techniques were compared using paired sample t-test. RESULTS: The values of SSI were all significantly higher in all measured areas compared to ARFI (p < 0.001 to p = 0.015). Quantitatively there was a higher mean SSI wave velocity value of 1,1 compared to 0.8 m/s measured by ARFI. CONCLUSION: SSI values are significantly higher than ARFI values when measuring the stiffness of testicular tissue and should only be compared with caution.

Prediction of Stent-Retriever Thrombectomy Outcomes by Dynamic Multidetector CT Angiography in Patients with Acute Carotid T or MCA Occlusions.

BACKGROUND AND PURPOSE: The selection of patients for endovascular therapy is an important issue in stroke imaging. The aim of this study was to determine the predictive value of 3 different dynamic CT angiography parameters, occlusion length, collateralization extent, and time delay to maximum enhancement, for latest generation of stent retriever thrombectomy recanalization outcomes in patients with acute ischemic stroke. MATERIALS AND METHODS: In this study, subjects were selected from an initial cohort of 2059 consecutive patients who had undergone multiparametric CT, including whole-brain CT perfusion. We included all patients with a complete occlusion of the M1 segment of the MCA or the carotid T and subsequent intra-arterial stent retriever thrombectomy. Dynamic CT angiography was reconstructed from whole-brain CT perfusion raw datasets. Angiographic outcome was scored by using the modified TICI scale; and clinical outcome, by using the modified Rankin Scale. Logistic regression analyses were performed to determine independent predictors of a favorable angiographic (mTICI = 3) and clinical outcome (mRS ≤2). RESULTS: Sixty-nine patients (mean age, 68 ± 14 years; 46% men) were included for statistical analysis. In the regression analysis, a short occlusion length was an independent predictor of favorable angiographic outcome (OR, 0.41; P < .05). Both collateralization grade (OR, 1.00; P > .05) and time delay to peak enhancement (OR, 0.90; P > .05) failed to predict a favorable angiographic outcome. None of the dynamic CT angiography predictors were significantly associated with clinical outcome on discharge (OR, 0.664-1.011; P = .330-.953) or at 90 days (OR, 0.779-1.016; P = .130-.845). CONCLUSIONS: A short occlusion length as determined by dynamic CT angiography is an independent predictor of a favorable angiographic outcome of stent retriever thrombectomy in patients with ischemic stroke.

Shear-wave elastography of the testis in the healthy man - determination of standard values.

PURPOSE: Real-time shear-wave elastography (SWE) is a newly developed technique for the sonographic quantification of tissue elasticity, which already is used in the assessment of breast and thyroid lesions. Due to limited overlying tissue, the testes are ideally suited for assessment using shear wave elastography. To our knowledge, no published data exist on real-time SWE of the testes. MATERIALS AND METHODS: Sixty six male volunteers (mean age 51.86±18.82, range 20-86) with no known testicular pathology underwent normal B-mode sonography and multi-frame shear-wave elastography of both testes using the Aixplorer ® ultrasound system (SuperSonic Imagine, Aix en Provence, France). Three measurements were performed for each testis; one in the upper pole, in the middle portion and in the lower pole respectively. The results were statistically evaluated using multivariate analysis. RESULTS: Mean shear-wave velocity values were similar in the inferior and superior part of the testicle (1.15 m/s) and were significantly lower in the centre (0.90 m/s). These values were age-independent. Testicular stiffness was significantly lower in the upper pole than in the rest of the testis with increasing volume (p = 0.007). CONCLUSION: Real-time shear-wave elastography proved to be feasible in the assessment of testicular stiffness. It is important to consider the measurement region as standard values differ between the centre and the testicular periphery. Further studies with more subjects may be required to define the normal range of values for each age group. Useful clinical applications could include the diagnostic work-up of patients with scrotal masses or male infertility.

[Stent-assisted recanalization of femoropopliteal arterial occlusive disease. Influence of stent design on patency rates]. / Stentgestützte Rekanalisation der femoropoplitealen arteriellen Verschlusskrankheit. Einfluss des Stentdesigns auf die Offenheitsrate.

BACKGROUND: Despite enormous technical progress the results of endovascular treatment of the femoropopliteal vasculature are unsatisfactory and its role is still controversially discussed. In the past decade numerous new stent designs have come onto the market but it is unclear whether they have benefits with respect to patency rates. OBJECTIVES: Comparison of published data on patency rates and target lesion revascularization rates after use of different stent designs in the femoropopliteal vasculature. MATERIAL AND METHODS: Analysis of 25 published studies and registries from 2006 to 2015 for classical open-cell stents, interwoven stents and partially or fully covered stents. RESULTS AND CONCLUSION: The published data are heterogeneous and comparative studies for different stent designs are completely missing. Over the past decade the patency rates after femoropopliteal stenting could be improved. According to available data stenting of short lesions < 5 cm does not show any benefit compared to isolated balloon angioplasty. Primary stenting is now recommended for intermediate and longer lesions > 6.4 cm. Due to the heterogeneity of published data a clear benefit for a specific stent design is not obvious; however, data for interwoven stents are promising and show a tendency towards improved patency, at least for certain lesions. Randomized controlled comparative trials are needed to confirm this result.

Postmortem computed tomography (PMCT) and autopsy in deadly gunshot wounds--a comparative study.

INTRODUCTION: Postmortem computed tomography (PMCT) data in gunshot-related death were evaluated by two reader groups and compared to the gold standard autopsy for the determination of forensic pathology criteria. MATERIALS AND METHODS: Reader group I consisted of two board-certified radiologists whereas one board-certified radiologist and one board-certified forensic pathologist formed group II. PMCT data of 51 gunshot-related deaths were evaluated for the forensic pathology criteria number of gun shots, localization of gunshot injury, caliber, and direction of the gunshot differentiating between entry and exit wound as well as associated injury to surrounding tissue. The results of both reader groups were compared to the each other and to autopsy findings considered as gold standard. RESULTS: Reader groups I and II and as gold standard the autopsy evaluation showed in general a good correlation between all results. The overall discrepancy rate was 12/51 (23.4%) cases for group I and 8/51 (15.6%) for group II. DISCUSSION: Ultimately, the designated reader is able to draw the following conclusion from the presented data. At first, physical autopsy is better than PMCT regarding the localization of most gunshot injuries. Second, PMCT presents with better results than physical autopsy in locating fragmented bullets/fragment clouds, and finally, PMCT results of two radiologists were equivalent to the results of one evaluating radiologist and one pathologist with the exception of caliber assessment. However, referring to the pure numbers, the slight but not significant difference in the overall discrepancy rate of both reader groups might indicate the advantage of combining expertise in evaluating imaging in cases of gunshot-related death.

Grating-based X-ray Dark-field Computed Tomography of Living Mice.

Changes in x-ray attenuating tissue caused by lung disorders like emphysema or fibrosis are subtle and thus only resolved by high-resolution computed tomography (CT). The structural reorganization, however, is of strong influence for lung function. Dark-field CT (DFCT), based on small-angle scattering of x-rays, reveals such structural changes even at resolutions coarser than the pulmonary network and thus provides access to their anatomical distribution. In this proof-of-concept study we present x-ray in vivo DFCTs of lungs of a healthy, an emphysematous and a fibrotic mouse. The tomographies show excellent depiction of the distribution of structural - and thus indirectly functional - changes in lung parenchyma, on single-modality slices in dark field as well as on multimodal fusion images. Therefore, we anticipate numerous applications of DFCT in diagnostic lung imaging. We introduce a scatter-based Hounsfield Unit (sHU) scale to facilitate comparability of scans. In this newly defined sHU scale, the pathophysiological changes by emphysema and fibrosis cause a shift towards lower numbers, compared to healthy lung tissue.

Evaluation of multimodality imaging using image fusion with MRI and CEUS in an experimental animal model.

PURPOSE: To evaluate the diagnostic benefits of multimodality imaging using image fusion with magnetic-resonance-imaging (MRI) and contrast-enhanced-ultrasound (CEUS) in an experimental small-animal-squamous-cell-carcinoma-model for the assessment of tissue hemodynamics and morphology. MATERIAL AND METHODS: Human hypopharynx-carcinoma-cells were injected subcutaneously into the left flank of 15 female athymic nude rats. After 10 daysof subcutaneous tumor growth, CEUS and MRI measurements were performed using a high-end-ultrasound-system and 3-T-MRI. After successful point-to-point or plan registration, the registered MR-images were simultaneously shown with the respective ultrasound sectional plane. Data evaluation was performed using the digitally stored video sequence data sets by two experienced radiologists using a subjective 5-point scale. RESULTS: CEUS and MRI are well-known techniques for the assessment of tissue hemodynamics (score: mean 3.8 ± 0.4 SD and score 3.8 ± 0.4 SD). Real-time image fusion of MRI and CEUS yielded a significant (p <  0.001) improvement in score (score 4.8 ± 0.4 SD). Reliable detection of small necrotic areas was possible in all animals with necrotic tumors. No significant intraobserver and interobserver variability was detected (kappa coefficient = +1). CONCLUSION: Image fusion of MRI and CEUS gives a significant improvement for reliable differentiation between different tumor tissue areas and simplifies investigations by showing the morphology as well as surrounding macro-/microvascularization.

Safety of Radioembolization with (90)Yttrium Resin Microspheres Depending on Coiling or No-Coiling of Aberrant/High-Risk Vessels.

PURPOSE: To evaluate the safety of radioembolization (RE) with (90)Yttrium ((90)Y) resin microspheres depending on coiling or no-coiling of aberrant/high-risk vessels. MATERIALS AND METHODS: Early and late toxicity after 566 RE procedures were analyzed retrospectively in accordance with the National Cancer Institute's Common Terminology Criteria for Adverse Events (CTCAE v3.0). For optimal safety, aberrant vessels were either coil embolized (n = 240/566, coiling group) or a more peripheral position of the catheter tip was chosen to treat right or left liver lobes (n = 326/566, no-coiling group). RESULTS: Clinically relevant late toxicities (≥ Grade 3) were observed in 1% of our overall cohort. The no-coiling group had significantly less "any" (P = 0.0001) or "clinically relevant" (P = 0.0003) early toxicity. There was no significant difference (P > 0.05) in delayed toxicity in the coiling versus the no-coiling group. No RE-induced liver disease was noted after all 566 procedures. CONCLUSION: RE with (90)Y resin microspheres is a safe and effective treatment option. Performing RE without coil embolization of aberrant vessels prior to treatment could be an alternative for experienced centers.

Strategies of collateral blood flow assessment in ischemic stroke: prediction of the follow-up infarct volume in conventional and dynamic CTA.

BACKGROUND AND PURPOSE: Collateral blood flow is an important prognostic marker in the acute stroke situation but approaches for assessment vary widely. Our aim was to compare strategies of collateral blood flow assessment in dynamic and conventional CTA in their ability to predict the follow-up infarction volume. MATERIALS AND METHODS: We retrospectively included all patients with an M1 occlusion from an existing cohort of 1912 consecutive patients who underwent initial multimodal stroke CT and follow-up MR imaging or nonenhanced CT. Collateralization was assessed in both conventional CT angiography and dynamic CT angiography by using 3 different collateral grading scores and segmentation of the volume of hypoattenuation. Arterial, arteriovenous, and venous phases were reconstructed for dynamic CT angiography, and all collateral scores and the volume of hypoattenuation were individually assessed for all phases. Different grading systems were compared by using the Bayesian information criterion calculated for multivariate regression analyses (Bayesian information criterion difference = 2-6, "positive"; Bayesian information criterion difference = 6-10, "strong"; Bayesian information criterion difference = >10, "very strong"). RESULTS: One hundred thirty-six patients (mean age, 70.4 years; male sex, 41.2%) were included. In the multivariate analysis, models containing the volume of hypoattenuation showed a significantly better model fit than models containing any of the 3 collateral grading scores in conventional CT angiography (Bayesian information criterion difference = >10) and dynamic CT angiography (Bayesian information criterion difference = >10). All grading systems showed the best model fit in the arteriovenous phase. For the volume of hypoattenuation, model fit was significantly higher for models containing the volume of hypoattenuation as assessed in the arteriovenous phase of dynamic CT angiography compared with the venous phase (Bayesian information criterion difference = 6.2) and the arterial phase of dynamic CT angiography (Bayesian information criterion difference = >10) and in comparison with conventional CT angiography (Bayesian information criterion difference = >10). CONCLUSIONS: The use of dynamic CT angiography within the arteriovenous phase by using quantification of the volume of hypoattenuation is the superior technique for assessment of collateralization among the tested approaches.

[Detection and evaluation of cartilage defects in the canine stifle joint - an ex vivo study using high-field magnetic resonance imaging]. / Ex-vivo-Untersuchungen zum Nachweis von Knorpeldefekten im Kniegelenk des Hundes mit der Hochfeld-Magnetresonanztomographie.

OBJECTIVE: The aim of our study was to implement and test an imaging protocol for the detection and evaluation of standardised cartilage defects using high-field magnetic resonance imaging (MRI) and to determine its limitations. MATERIAL AND METHOD: A total of 84 cartilage defects were created in the femoral condyles of euthanized dogs with a minimum body mass of 25 kg. The cartilage defects had a depth of 0.3 to 1.0 mm and a diameter of 1 to 5 mm. T1-FLASH-3D-WE-sequences with an isotropic voxel size of 0.5 x 0.5 x 0.5 mm and an anisotropic voxel size of 0.3 x 0.3 x 0.8 mm were used. In addition to quantitative evaluation of the cartilage defects, the sig- nal intensities, signal-to-noise ratios and contrast-to-noise ratios of the cartilage were determined. Of special interest were the limita- tions in identifying and delineating the standardised cartilage defects. RESULTS: With the anisotropic voxel size, more cartilage defects were detectable. Our results demonstrated that cartilage defects as small as 3.0 mm in diameter and 0.4 mm in depth were reliably detected using anisotropic settings. Cartilage defects below this size were not reliably detected. CONCLUSION AND CLINICAL RELEVANCE: We found that for optimal delineation of the joint cartilage and associated defects, a higher in-plane resolution with a larger slice thickness should be used, corresponding to the anisotropic settings employed in this study. For the delineation of larger cartilage defects, both the anisotropic and isotropic imaging methods can be used.

[Gastroenteropancreatic endocrine tumors]. / Gastroenteropankreatische endokrine Tumoren.

CLINICAL/METHODICAL ISSUE: Gastroenteropancreatic neuroendocrine tumors (GEP-NET) are a rare, heterogeneous group of neoplasms. Only 2% of gastrointestinal tumors belong to the group of neuroendocrine neoplasms. STANDARD RADIOLOGICAL METHODS: A wide spectrum of diagnostic imaging modalities is available: apart from ultrasound not only computed tomography (CT) but also magnetic resonance imaging (MRI) and positron emission tomography CT (PET-CT) play an important role in detection and staging of GEP-NETs. METHODICAL INNOVATIONS: The PET-CT technique with somatostatin analogues is used for staging as well as for evaluation and monitoring of treatment with peptide radionuclide radiation therapy. PERFORMANCE: According to the literature NETs of the small bowel with a size over 3 cm can be detected with a sensitivity of 84.7% and a specificity of 96.6% using CT enteroclysis and MR enteroclysis provides the detection of NETs of the small bowel in 93.3% of cases. 'The sensitivity of MRI in detection of pancreatic NETs is between 74% and 100% and is, therefore, higher than CT. Detection of small primary tumors is carried out using PET-CT and seems to be the most sensitive imaging modality to identify the exact location. On the other hand MRI has to be regarded as the best imaging modality for detection of liver metastases compared to CT and PET-CT. ACHIEVEMENTS: The role of diagnostic imaging is to identify the exact location of the primary tumor and possible metastases, to define an appropriate therapy and to monitor treatment effects; however, the choice of the most appropriate diagnostic imaging modality varies depending on the location and type of the primary tumor. PRACTICAL RECOMMENDATIONS: The GEP-NETs are predominantly well-vascularized; therefore, dual-phase CT/MR imaging with the arterial and venous phases after contrast media injection is mandatory for detection and localization of primary tumors and metastases. For whole body staging CT and PET-CT should be performed.

[Radiological diagnostics of multiple myeloma]. / Radiologische Diagnostik des multiplen Myeloms.

CLINICAL/METHODICAL ISSUE: Robust and reliable imaging methods are required to estimate the skeletal tumor load in multiple myeloma, as well as for the diagnosis of extraskeletal manifestations. Imaging also plays an essential role in the assessment of fracture risk and of vertebral fractures. STANDARD RADIOLOGICAL METHODS: The conventional skeletal survey has been the gold standard in the imaging of multiple myeloma for many years. METHODICAL INNOVATIONS: Other modalities which have been investigated and are in use are whole-body computed tomography (WBCT), 18F-fluorodeoxyglucose positron emission tomography computed tomography (FDG PET-CT) and whole-body magnetic resonance imaging (WBMRI). These techniques are able to depict both mineralized bone and the bone marrow with a high sensitivity for myeloma lesions. PERFORMANCE: Several studies have shown that cross-sectional imaging is superior to the skeletal survey in the detection of myeloma lesions and WBMRI has been shown to be significantly more sensitive than WBCT for the detection of focal myeloma lesions as well as for diffuse infiltration. The FDG PET-CT technique has a sensitivity comparable to WBMRI. ACHIEVEMENTS: Due to the higher sensitivity in the detection of myeloma lesions WBCT and WBMRI should replace the skeletal survey. PRACTICAL RECOMMENDATIONS: A WBCT should be performed if there is suspicion of multiple myeloma. If no focal lesions are found WBMRI or at least MRI of the spine and pelvis should be additionally performed if available. If WBMRI has been initially performed and focal lesions are present, an additional WBCT may be performed to assess the extent of bone destruction and fracture risk. In cases of monoclonal gammopathy of undetermined significance (MGUS), solitary and smoldering myeloma, a WBMRI, if available, should be performed in addition to WBCT.

Dual-energy CT pulmonary angiography in patients with suspected pulmonary embolism: value for the detection and quantification of pulmonary venous congestion.

OBJECTIVE: To evaluate if vascular and pulmonary parenchymal enhancement values in dual-energy (DE) CT pulmonary angiography (CTPA) can suggest the diagnosis of pulmonary congestion. METHODS: DE-CTPA images of 90 out of 1321 patients negative for pulmonary embolism showed signs of congestive heart failure. We measured DE-derived pulmonary parenchymal [perfused blood volume (PBV)], pulmonary artery (PA) and left atrium (LA) enhancement values in these patients and in 142 control patients. Enhancement values were compared between the populations and correlated with serum values of B-type natriuretic peptide (BNP) and proBNP, where available. RESULTS: No significant difference of PBV but significant differences of mean PA and LA enhancement and individual enhancement differences (PA - LA) were found between the populations. PA - LA was higher in patients with elevated BNP and proBNP and was positively correlated with these values. Receiver operating characteristic analysis revealed a moderate discriminatory power of the PA - LA difference for the presence of cardiac biomarker elevations. CONCLUSION: PBV in DE-CTPA is not altered in patients with signs of congestive heart failure. However, differences in enhancement values in the pre- and post-pulmonary vessels were found in comparison with the control population. ADVANCES IN KNOWLEDGE: Altered pulmonary vascular haemodynamics in pulmonary venous congestion are not reflected in dual-energy-derived PBV maps. In the diagnosis of left heart failure in patients with chest pain and dyspnoea, density measurements in the pulmonary artery and in the left atrium in CTPA images may be a helpful diagnostic tool.

Role of diffusion-weighted MRI in differentiation of hepatic abscesses from non-infected fluid collections.

AIM: To evaluate the role of diffusion-weighted magnetic resonance imaging (DW-MRI) in the differentiation of hepatic abscesses from non-infected fluid collections. MATERIALS AND METHODS: In this retrospective study, 22 hepatic abscesses and 27 non-infected hepatic fluid collections were examined in 27 patients who underwent abdominal MRI including DW-MRI. Two independent observers reviewed T2-weighted + DW-MRI and T2-weighted + contrast-enhanced T1-weighted (CET1W) images in two sessions. Detection rates and confidence levels were calculated and compared using McNemar's and Wilcoxon's signed rank tests, respectively. Apparent diffusion coefficient (ADC) values of abscesses and non-infected fluid collections were compared using the t-test. Receiver operating characteristic (ROC) curves were constructed. RESULTS: There was no statistically significant difference in the accuracy of detecting abscesses using T2-weighted + DW-MRI (both observers: 21/22, 95.5%) versus T2-weighted + CET1W images (observer 1: 21/22, 95.5%; observer 2: 22/22, 100%; p < 0.01). Mean ADC values were significantly lower with abscesses versus non-infected fluid collections (0.83 ± 0.24 versus 2.25 ± 0.61 × 10(-3) mm(2)/s; p < 0.001). With ROC analysis there was good discrimination of abscess from non-infected fluid collections at a threshold ADC value of 1.36 × 10(-3) mm(2)/s. CONCLUSION: DW-MRI allows qualitative and quantitative differentiation of abscesses from non-infected fluid collections in the liver.

Evaluation of multimodality imaging using image fusion with ultrasound tissue elasticity imaging in an experimental animal model.

PURPOSE: To evaluate the ultrasound tissue elasticity imaging by comparison to multimodality imaging using image fusion with Magnetic Resonance Imaging (MRI) and conventional grey scale imaging with additional elasticity-ultrasound in an experimental small-animal-squamous-cell carcinoma-model for the assessment of tissue morphology. METHOD AND MATERIALS: Human hypopharynx carcinoma cells were subcutaneously injected into the left flank of 12 female athymic nude rats. After 10 days (SD ± 2) of subcutaneous tumor growth, sonographic grey scale including elasticity imaging and MRI measurements were performed using a high-end ultrasound system and a 3T MR. For image fusion the contrast-enhanced MRI DICOM data set was uploaded in the ultrasonic device which has a magnetic field generator, a linear array transducer (6-15 MHz) and a dedicated software package (GE Logic E9), that can detect transducers by means of a positioning system. Conventional grey scale and elasticity imaging were integrated in the image fusion examination. After successful registration and image fusion the registered MR-images were simultaneously shown with the respective ultrasound sectional plane. Data evaluation was performed using the digitally stored video sequence data sets by two experienced radiologist using a modified Tsukuba Elasticity score. The colors "red and green" are assigned for an area of soft tissue, "blue" indicates hard tissue. RESULTS: In all cases a successful image fusion and plan registration with MRI and ultrasound imaging including grey scale and elasticity imaging was possible. The mean tumor volume based on caliper measurements in 3 dimensions was ~323 mm3. 4/12 rats were evaluated with Score I, 5/12 rates were evaluated with Score II, 3/12 rates were evaluated with Score III. There was a close correlation in the fused MRI with existing small necrosis in the tumor. None of the scored II or III lesions was visible by conventional grey scale. CONCLUSION: The comparison of ultrasound tissue elasticity imaging enables a secure differentiation between different tumor tissue areas in comparison to image fusion with MRI in our small study group. Therefore ultrasound tissue elasticity imaging might be used for fast detection of tumor response in the future whereas conventional grey scale imaging alone could not provide the additional information. By using standard, contrast-enhanced MRI images for reliable and reproducible slice positioning, the strongly user-dependent limitation of ultrasound tissue elasticity imaging may be overcome, especially for a comparison between baseline and follow-up measurements.

[Radiological diagnostics in CUP syndrome]. / Radiologische Diagnostik des CUP-Syndroms.

CLINICAL/METHODICAL ISSUE: Imaging plays an essential role in the therapeutic management of cancer of unknown primary (CUP) patients for localizing the primary tumor, for the identification of tumor entities for which a dedicated therapy regimen is available and for the characterization of clinicopathological subentities that direct the subsequent diagnostic and therapeutic strategy. STANDARD RADIOLOGICAL METHODS: Modalities include conventional x-ray, computed tomography (CT), magnetic resonance imaging (MRI) and ultrasound as well as positron emission tomography (PET)-CT and MRI-PET. PERFORMANCE: In whole body imaging CT has a high sensitivity for tumor entities which frequently present as a metastasized cancer illness. According to the current literature CT is diagnostic in 86% of patients with pancreatic carcinoma, in 36% of patients with colon carcinoma and in 74% of patients with lung carcinoma. Additionally a meta-analysis showed that for patients with squamous cell carcinoma and cervical lymph node metastases a positive diagnosis was possible in 22% of the cases using CT, in 36% using MRI and in 28-57% using 18F-fluorodeoxyglucose PET-CT ((18)F-FDG PET-CT). In addition, MRI plays an important role in the localization of primary occult tumors (e.g. breast and prostate) because of its high soft tissue contrast and options for functional imaging. ACHIEVEMENTS: At the beginning of the diagnostic algorithm stands the search for a possible primary tumor and CT of the neck, thorax and abdomen is most frequently used for whole body staging. Subsequent organ-specific imaging examinations follow, e.g. mammography in women with axillary lymphadenopathy. For histological and immunohistochemical characterization of tumor tissue, imaging is also applied to identify the most accessible and representative tumor manifestation for biopsy. Tumor biopsy may be guided by CT, MRI or ultrasound and MRI also plays a central role in the localization of primary occult tumors because of superior soft tissue contrast and options for functional imaging (perfusion, diffusion), e.g. investigation of breast carcinoma or prostate carcinoma. PRACTICAL RECOMMENDATIONS: Whole body staging stands at the beginning of the diagnostic algorithm in CUP syndrome to localize a potential primary tumor. Clinically, contrast-enhanced CT of the neck, thorax and abdomen is frequently applied; however, many studies have demonstrated augmented sensitivity of (18)F-FDG PET-CT for the detection of primary tumors and metastatic tumor manifestations.