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Objective: The aim of this study was to compare the microcalcification detectability in an anthropomorphic phantom model regarding number, size, and shape in full-field digital mammography (FFDM), synthetically reconstructed 2-dimensional (Synthetic-2D) images, and digital breast tomosynthesis (DBT) performed with 2 different x-ray mammography systems., Materials and Methods: Simulated microcalcifications of different numbers (0 to >39), sizes (diameter, 100-800 μm), and shapes (round vs heterogeneous) were scattered by random distribution on 50 film phantoms each divided in 4 quadrants. The FFDM and DBT x-rays were taken from each of these 50 films with both x-ray mammography systems (SenoClaire; GE Healthcare, Selenia Dimensions, Hologic) using an anthropomorphic scattering body and automatic exposure control. The resulting exposure factors were similar to a clinical setting. The synthetically reconstructed 2D images were generated automatically on both systems. All FFDM, Synthetic-2D, and DBT images were interpreted in randomized order and independently of each other by 6 radiologists using a structured questionnaire., Results: The number categories of simulated microcalcifications were correctly evaluated in 55.3% of instances (quadrant by reader) in FFDM, 50.9% in the Synthetic-2D views, and 59.5% in DBT, summarized for 200 quadrants per reader for each Device A and B, respectively. Full-field digital mammography was superior to Synthetic-2D (mean difference, 4%; 95% confidence interval [CI], 2%-7%; P < 0.001), and DBT was superior to both FFDM (mean difference, 4%; 95% CI, 2%-7%; P = 0.002) and Synthetic-2D (mean difference, 9%; 95% CI, 6%-11%; P < 0.001). This trend was consistent in all subgroup analyses. The number of the smallest microcalcifications (100-399 μm) was correctly evaluated in 25.2% of the FFDM, in 14.2% for Synthetic-2D, and in 28.3% of the DBT images. Underestimations of the number of simulated microcalcifications were more common than overestimations. Regarding the size categories of simulated microcalcifications, the rates of correct assessments were in 45.4% of instances in FFDM, 39.9% in the Synthetic-2D views, and 43.6% in DBT, summarized for 200 quadrants per reader and both imaging devices., Conclusions: In the presented in vitro environment using an anthropomorphic phantom model, standard full-field digital x-ray mammography was superior to synthetically reconstructed 2-dimensional images in the detection of simulated microcalcifications. In view of these results, it is questionable whether Synthetic-2D images can replace FFDM in clinical examinations at the present time. Further investigations are needed to assess the clinical impact of the in vitro results.

Objectives: T1-weighted (T1w) contrast-enhanced magnetic resonance imaging (MRI) of the small bowel at 1.5 T magnetic field strength has become a standard technique in investigating diseases of the small bowel. High-field MRI potentially offers improved soft tissue contrast and spatial resolution, providing increased image detail. The purpose of this study was to evaluate the feasibility of contrast-enhanced small bowel MRI at 7 T and to compare results with 1.5 T., Materials and Methods: Twelve healthy volunteers underwent small bowel MRI on a 1.5 T and 7 T MRI system. A coronal fat-saturated T1w spoiled gradient-echo sequence (3-dimensional [3D] FLASH) was applied precontrast and at 20 seconds, 75 seconds, and 120 seconds after intravenous contrast administration. Furthermore, late-phase coronal and axial fat-saturated T1w 2-dimensional (2D) FLASH data sets were acquired. Visual evaluation of tissue contrast and image detail of the small bowel wall and mesentery as well as contrast ratios were compared between 1.5 T and 7 T in an intraindividual comparison. In addition, subjective ratings of image impairment by artifacts were assessed at both field strengths., Results: Magnetic resonance imaging of the small bowel at 7 T revealed equal tissue contrast and image detail compared with 1.5 T. Higher contrast and improved image detail of mesentery structures at 7 T were found in nonenhanced 3D FLASH. Quantitatively measured contrast between the bowel wall and bowel lumen showed significantly lower contrast at 7 T in nonenhanced 3D FLASH and in late-phase 2D FLASH. Image quality was more impaired at 7 T compared with 1.5 T, mainly due to increased susceptibility artifacts and B1 inhomogeneities., Conclusions: T1-weighted contrast-enhanced MRI of the small bowel at 7 T represents a promising MR technique for establishing ultra-high magnetic field strengths in clinical applications. Despite increased artifacts at 7 T, depiction of the small bowel was achieved with comparable quality to the current state-of-the-art field strength of 1.5 T. Assessment of potential diagnostic benefits should be the focus of future high-field MRI studies.

Objectives: This study aimed to assess the diagnostic performance of integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) of the breast for lesion detection and local tumor staging of patients with primary breast cancer in comparison to PET/computed tomography (CT) and MRI., Materials and Methods: The study was approved by the local institutional review board. Forty-nine patients with biopsy-proven invasive breast cancer were prospectively enrolled in our study. All patients underwent a PET/CT, and subsequently, a contrast-enhanced PET/MRI of the breast after written informed consent was obtained before each examination. Two radiologists independently evaluated the corresponding data sets (PET/CT, PET/MRI, and MRI) and were instructed to identify primary tumors lesions as well as multifocal/multicentric and bilateral disease. Furthermore, the occurrence of lymph node metastases was assessed, and the T-stage for each patient was determined. Histopathological verification of the local tumor extent and the axillary lymph node status was available for 30 of 49 and 48 of 49 patients, respectively. For the remaining patients, a consensus characterization was performed for the determination of the T-stage and nodal status, taking into account the results of clinical staging, PET/CT, and PET/MRI examinations. Statistical analysis was performed to test for differences in diagnostic performance between the different imaging procedures. P values less than 0.05 were considered to be statistically significant., Results: Positron emission tomography/MRI and MRI correctly identified 47 (96%) of the 49 patients with primary breast cancer, whereas PET/CT enabled detection of 46 (94%) of 49 breast cancer patients and missed a synchronous carcinoma in the contralateral breast in 1 patient. In a lesion-by-lesion analysis, no significant differences could be obtained between the 3 imaging procedures for the identification of primary breast cancer lesions (P > 0.05). Positron emission tomography/MRI and MRI allowed for a correct identification of multifocal/multicentric disease in 3 additional patients if compared with PET/CT. For the definition of the correct T-stage, PET/MRI and MRI showed identical results and were correct in significantly more cases than PET/CT (PET/MRI and MRI, 82%; PET/CT, 68%; P < 0.05). Furthermore, the calculated sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy for the detection of nodal positive patients (n = 18) were 78%, 94%, 88%, 88%, and 88% for PET/CT; 67%, 87%, 75%, 82%, and 80% for MRI; and 78%, 90%, 82%, 88%, and 86% for PET/MRI, respectively. Differences between the imaging modalities were not statistically significant (P > 0.05)., Conclusions: Integrated PET/MRI does not provide diagnostic advantages for local tumor staging of breast cancer patients in comparison to MRI alone. Positron emission tomography/MRI and MRI enable an improved determination of the local tumor extent in comparison to PET/CT, whereas all 3 imaging modalities offer a comparable diagnostic performance for the identification of axillary disease.

Objectives: The objective of this study was to evaluate whether the use of automatically generated maps of bowel motility (motility mapping) in magnetic resonance imaging (MRI) leads to an increased detection rate of inflammatory bowel disease., Materials and Methods: Fifty consecutive patients with suspected or known inflammatory bowel disease who underwent bowel MRI using a 1.5-T scanner were analyzed retrospectively. In addition to standard small bowel magnetic resonance protocol, a dynamic coronal T2-weighted sequence (dynamic MRI) was acquired. Dynamic sequences were used to automatically generate a parametric map depicting bowel motility. Two readings of the MRI were performed: first, evaluation of static MRI alone and second, evaluation of static MRI combined with dynamic MRI (motility mapping). Static MRI was analyzed on parameters defining inflammation (morphology, enhancement). Dynamic MRI (motility mapping) was evaluated on the basis of a color-coded scheme displaying hypomotility and hypermotility., Results: Using motility maps, additional inflammatory lesions were found in 13 (26%) of the 50 patients, resulting in a significantly higher detection rate using static MRI together with motility mapping compared with static MRI alone (P = 0.0002). Overall, 66 inflammatory lesions of the bowel were detected in a total of 38 patients (static MRI + motility mapping) versus 51 lesions in 34 patients (sole evaluation of static MRI)., Conclusions: Motility assessment of the bowel provides additional information and improves the detection of inflammatory lesions in MRI.

Objectives: Magnetic resonance colonography (MRC) is a well-accepted, noninvasive imaging modality for the depiction of inflammatory bowel disease. Diffusion-weighted imaging (DWI) is very helpful to display inflammatory lesions. The aim of this retrospective study was to assess whether intravenous contrast is needed to depict inflammatory lesions in bowel magnetic resonance imaging if DWI is available., Materials and Methods: Thirty-seven patients (23 females, 14 males; mean age, 14.6 years) underwent MRC on a 1.5-T scanner (MAGNETOM Avanto; Siemens). Contrast-enhanced T1-weighted (ce-T1-w) sequences and DWI sequences in axial and coronal planes (b = 50, 500, 1000) were acquired. Two reviewers evaluated (1) DWI, (2) ce-T1-w MRC, as well as (3) DWI and ce-T1-w MRC concerning lesion conspicuity. The preferred b value was assessed. Colonoscopy was performed within 1 week, including biopsies serving as the reference standard. Sensitivities and specificities were calculated, and interobserver variability was assessed., Results: Mean sensitivity and specificity of the 2 readers for the depiction of inflammatory lesions were 78.4%/100% using ce-T1-w MRC, 95.2%/100% using DWI, and 93.5%/100% combining both imaging techniques compared with colonoscopy including results of the histopathological samples. In 6 patients, inflammatory lesions were only detected by DWI; in another 6 patients, DWI detected additional lesions. The κ values for the 2 readers were excellent (k = 0.92-0.96). The preferred b value with the best detectability of the lesion was b1000 in 28 of the 30 patients (93.3%) with restricted diffusion., Conclusions: Diffusion-weighted imaging of the bowel identified inflammatory lesions with high accuracy and revealed lesions that were not detectable with ce-T1-w imaging alone. A b value of 1000 showed the best lesion detectability.

Objectives: The objective of this study was to assess the diagnostic value of integrated positron emission tomography/magnetic resonance imaging (PET/MRI) for whole-body staging of patients with recurrent gynecological pelvic malignancies, in comparison to whole-body MRI alone., Materials and Methods: The study was approved by the local institutional ethics committee. Written informed consent was obtained before each examination. Thirty-four consecutive patients with a suspected recurrence of cervical (n = 18) or ovarian (n = 16) cancer were prospectively enrolled for an integrated PET/MRI examination, which comprised a diagnostic, contrast-enhanced whole-body MRI protocol including dedicated sagittal dynamic imaging of the pelvis. Two radiologists separately evaluated the data sets regarding lesion count, lesion detection, lesion characterization, and diagnostic confidence. Mean and median values were calculated for each rating. Statistical analyses were performed both per-patient and per-lesion bases using a Wilcoxon signed-rank test to indicate potential significant differences among PET/MRI and MRI (alone) data sets., Results: Malignant lesions were present in 25 of the 34 patients. Positron emission tomography/magnetic resonance imaging offered correct and superior identification of all 25 patients with cancer recurrence, compared with MRI alone (23/25). A total of 118 lesions (malignant, 89; benign, 29) were detected. Positron emission tomography/magnetic resonance imaging correctly identified 88 (98.9%) of 89 malignant lesions, whereas MRI alone allowed for correct identification of 79 (88.8%) of the 89 malignant lesions. In addition, PET/MRI provided significantly higher lesion contrast and diagnostic confidence in the detection of malignant lesions (P < 0.001) compared with MRI alone., Conclusions: These first results demonstrate the high diagnostic potential of integrated PET/MRI for the assessment of recurrence of female pelvic malignancies compared with MRI alone.

Objectives: The aim of this study was to investigate the performance of 2 different ultrasmall superparamagnetic iron oxide particles-based contrast agents for intravascular magnetic resonance lymphography in normal, inflammatory, and tumor-bearing lymph nodes in rabbits., Materials and Methods: Two USPIO agents were assessed: Sinerem and P904 (both Guerbet Research, Aulnay-sous-Bois, France). Signal change of popliteal and paraaortic lymph nodes were studied in VX-2 tumor-bearing rabbits (n = 4) and rabbits in whom complete Freund adjuvant had been applied (n = 6). Image acquisition was performed before and 5 to 120 minutes and 24 hours after bolus injection of Sinerem (n = 5) and P904 (n = 5). Lymph node size was assessed and signal-to-noise ratios of lymph nodes were calculated. The contrast agents were compared regarding nodal signal changes over time. Furthermore, sensitivities, specificities, and negative and positive predictive values were calculated for both contrast agents, with histopathology serving as the standard of reference., Results: No statistically significant size differences were detected between normal, reactively enlarged and tumor-infiltrated lymph nodes. Signal change over time showed greater differences between benign and metastatic lymph nodes for P904 especially at 24 hours after injection, whereas Sinerem showed the highest signal loss in benign nodes. After 24 hours, P904 showed a higher sensitivity (0.75 vs 0.67) and higher specificity (1 vs 0.94) compared with Sinerem. At earlier time points, sensitivity for Sinerem was lower (0.33), whereas for P904, sensitivity at 120 minutes was as good as after 24 hours (0.75)., Conclusion: Magnetic resonance lymphography with USPIO contrast agents allows for differentiation of reactively enlarged lymph nodes compared with metastatic nodes. P904 yielded higher sensitivity and specificity values, with higher signal differences between benign and malignant enlarged lymph nodes. Furthermore, diagnosis seems to be possible earlier. This agent therefore seems to be a promising tool for staging cancer patient.

Objectives: : To evaluate the performance of a gadolinium-based contrast compound (P846) as well as an ultra-small particle of iron oxide agent (P904) in contrast-enhanced magnetic resonance angiography (MRA) in rabbits and to compare those agents with gadoterate meglumine (Gd-DOTA) for first pass and steady state imaging., Materials and Methods: : A total of 6 rabbits underwent contrast-enhanced MRA of the aorta and its branches at 3 different time points. All examinations were performed on a 1.5T MR (Siemens HealthCare, Magnetom Espree), and the contrast agents were applied in random order. Image data were acquired using a time-resolved MRA sequence (time-resolved angiography with stochastic trajectories) during the first pass to assess the bolus phase and a high-resolution MRA sequence followed by repetitive measurements over the next 10 minutes for all 3 agents to evaluate the postbolus phase. Two radiologists reviewed the images in consensus blinded to the contrast agent used. Signal-to-noise ratio and contrast-to-noise ratio for three-dimensional high-resolution MRA were calculated for each time point and agent. Image quality was consensually evaluated on a 4-point Likert scale. A Wilcoxon-Mann-Whitney U test was used for comparison with P < 0.05 as level of statistical significance., Results: : All agents led to diagnostic MR angiograms in all 6 rabbits. The time-resolved angiography with stochastic trajectories datasets provided detailed information about the bolus phase for all the 3 agents. During the first pass, P904 and P846 proved to be superior to Gd-DOTA with the highest peak enhancement for P846. In the postbolus phase up to 10 minutes postcontrast injection, P904 proved to be superior to the other agents. All the agents led to excellent image quality, with no statistical difference to a maximum of 3 minutes postinjection, whereas thereafter images with Gd-DOTA and P846 were assessed as nondiagnostic., Conclusions: : P846 and P904 proved to be superior to Gd-DOTA for time-resolved MRA. The ultra-small particle of iron oxide compound P904 showed continuous high signal over 10 minutes and seems to be best suited for first pass and steady-state imaging.

Objective: With the successful implementation of ultra-high-field imaging in neuro- and musculoskeletal imaging, the interest of scientific research expanded toward whole-body applications. The aim of this study was to assess the feasibility of dynamic contrast-enhanced renal magnetic resonance imaging (MRI) at 7 Tesla (T), with optimization and implementation of a dedicated examination protocol., Material and Methods: In vivo dynamic contrast-enhanced high-field examinations were obtained in 10 healthy subjects on a 7 T whole-body MR scanner. A custom-built body transmit/receive reduced radiofrequency (RF) coil suitable for RF shimming was used for image acquisition. The examination protocol included (1) true fast imaging with steady-state precession imaging, (2) T2-weighted turbo spine echo imaging, (3) T1-weighted (T1w) in- and opposed-phase imaging, and (4) a fat-saturated 2D FLASH sequence. For dynamic imaging, gadobutrol was injected intravenously and T1w 3D FLASH images were obtained precontrast and at 20, 70, and 120 seconds delay. Qualitative image analysis was performed by 2 senior radiologists using a 3-point scale (1 = poor, 2 = moderate, 3 = good quality). Signal-to-noise ratio and contrast-to-noise ratio (CNR) of the renal cortex/medulla were measured for all sequences. For statistical analysis, a Wilcoxon Rank Test was used., Results: All examinations were performed successfully and were well tolerated by all subjects without any side effects. Best overall image quality was rated for the T1w 2D FLASH sequence with an average score of 2.57, followed by the contrast-enhanced 3D FLASH sequence in the equilibrium phase (mean, 2.22). T2-weighted turbo spine echo imaging provided the weakest overall image quality score (1.30) and was most impaired by artifacts. Quantitative analysis showed highest CNR between cortex and medulla for arterial phase 3D FLASH imaging (CNR = 12.2), providing a statistically significant difference to all other sequences, except for the in- and opposed-phase and the fat-saturated 2D FLASH sequence. Conversely, equilibrium phase FLASH imaging yielded the weakest CNR score of 3.6., Conclusion: This feasibility study reveals the diagnostic potential and current constraints of ultra-high-field abdominal MRI. Our initial results demonstrate the potential of dedicated dynamic-contrast 7 T renal MRI and the need for further optimization of imaging sequences and RF coil concepts.

Objective: To retrospectively evaluate the performance of two water-equivalent oral contrast agents [locust bean gum (LBG)-mannitol and VoLumen] concerning their potential to distend the bowel while avoiding contrast-associated artifacts in PET/computed tomography., Methods: PET/computed tomography examinations of 30 patients with two different oral contrast agents were reviewed. Bowel distension, intraluminal density, and potential contrast-associated artifacts were assessed for stomach, jejunum, and ileum. Statistical significance was tested by Student's t-test., Results: Distension was slightly better in the stomach with VoLumen as compared with LBG-mannitol whereas LBG-mannitol was found to slightly better distend the small bowel. This difference proved to be statistically significant for the jejunum. A statistically significant difference was detected for intraluminal density with higher densities for VoLumen. This difference, however, did not result in a higher incidence of PET artifacts with VoLumen., Conclusion: LBG-mannitol provides excellent bowel distension, thereby avoiding contrast-associated PET artifacts. If this solution is not available, VoLumen provides a satisfactory alternative for bowel distension without relevant PET artifacts.

Objective: The purpose of this study was to assess the diagnostic value and safety of the contrast agent gadoterate meglumine (Gd-DOTA, DOTAREM, Guerbet, Roissy CdG Cedex, France) in the setting of a postmarketing surveillance study., Materials and Methods: Between January 2004 and October 2005, radiologists in 61 radiologic institutions were asked to document the routine use of Gd-DOTA in a questionnaire. In addition to assessing the image quality and diagnostic value of the contrast-enhanced magnetic resonance imaging scans, we statistically evaluated and analyzed demographic and safety data., Results: A total of 24,308 patients were intravenously injected with Gd-DOTA for various diagnostic examinations. The examination allowed for establishing a diagnosis in >99% of cases and image quality was rated as "excellent" or "good" in 97.5% of all cases. Adverse events were noted in only 0.4% of the examinations and were mostly rated as minor, such as feeling of warmth or taste alteration. There was one serious adverse event, albeit with complete recovery., Conclusion: This postmarketing surveillance study suggests diagnostic efficacy and a favorable clinical safety profile of Gd-DOTA in clinical practice.