Gadobenate dimeglumine is effective for MR imaging evaluation of breast vessels at doses as low as 0.05 mmol/kg. One-sided increased vascularity is an MR imaging finding frequently associated with ipsilateral invasive breast cancer.

The investigation of small bowel morphology is often mandatory in many patients with Crohn's disease. Traditional radiological techniques (small bowel enteroclysis and small bowel follow-through) have long been the only suitable methods for this purpose. In recent years, several alternative imaging techniques have been proposed. To review the most recent advances in imaging studies of the small bowel, with particular reference to their possible application in Crohn's disease, we conducted a complete review of the most important studies in which traditional and newer imaging methods were performed and compared in patients with Crohn's disease. Several radiological and endoscopic techniques are now available for the study of the small bowel; each of them is characterized by a distinct profile of favourable and unfavourable features. In some cases, they may also be used as complementary rather than alternative techniques. In everyday practice, the choice of the technique to be used stands upon its availability and a careful evaluation of diagnostic accuracy, clinical usefulness, safety and cost. The recent development of innovative imaging techniques has opened a new and exciting area in the exploration of the small bowel in Crohn's disease patients.

IntroductionThis article summarizes the principles and major technical aspects of dynamic magnetic resonance (MR) imaging of the breast with particular emphasis on pulse sequence parameters, contrast agent dosage, and image postprocessing. A detailed list of clinical indications for dynamic breast MR imaging is given, and an interpretation score system provided. The performance of the MR examination in terms of sensitivity and specificity for lesion detection and characterization is discussed in detail, as are the pharmacokinetics and safety of the twocompartment Gd-based contrast agents. The effects of stressing temporal and spatial resolution are also discussed. Finally, intriguing new directions in breast MR imaging are presented in terms of the potential for Gdchelates with high T1-relaxivity, blood-pool contrast agents, and proton MR spectroscopy.Breast MR imaging: technique, tips, and tricksThe first applications of magnetic resonance (MR) imaging to the breast were disappointing. Classic spin-echo T1-, proton-density-, or T2-weighted sequences were not able to distinguish malignant from benign tumors [1,2]. This scenario changed dramatically with the introduction of intravenously administered paramagnetic gadoliniumbased contrast agents: tumors showed greater contrast enhancement than normal gland parenchyma, and strong enhancement was observed for malignant, invasive tumors in particular [3]. This behavior is due to the neoangiogenesis related to the growth of the tumor: breast malignancies are more highly vascular (more and larger vessels) and have increased permeability (up to eightfold more) compared to normal parenchyma. Moreover, an increased interstitial space (between three-and fivefold more than normal parenchyma) functions as a large distribution space for the contrast agent [4]. The advent of rapid MR sequences together with field gradients of increased power and slew rate have permitted the definition of a dynamic technique that today is considered standard for MR imaging of the breast.MR imaging of the breast needs to be performed during the second week of the menstrual cycle in premenopausal women and 2-3 months after the interruption of hormone replacement therapy in postmenopausal women. An earlier recommendation to wait 6 months after surgery and 12-18 months after radiation therapy in order to avoid false-positive findings is no longer relevant [5]: MR imaging performed about 1 month after surgery was shown to have a sensitivity of 95% and a positive predictive value of 92% for malignancy [6].Imaging is performed with patients in the prone position using a dedicated bilateral breast coil and a longline venous access to a cubital or hand vein. In order to avoid misregistration artifacts on subtracted images, patients should be carefully instructed not to move during the 10-15 min required for the full examination.Dynamic imaging is performed after obtaining scout views and, optionally, short-time fast inversion recovery or T2-weighted fat-saturated fast spin-echo images. The dynamic sequen...

The aim of our study was to test the possibility of using image subtraction in detecting enhancing lesions in brain MR scans with and without magnetization transfer (MT) in multiple sclerosis (MS). Ten MS patients underwent 1.5-T MR imaging of the brain with spin-echo T1-weighted sequences with and without MT, repeated after 0.1 mmol/kg of an usual two-compartment paramagnetic contrast agent (Gadoteridol, Gd-HP-DO3A). Precontrast images were subtracted from postcontrast. Enhancing lesions were counted on the postcontrast images only (post-Gd), comparing pre- and postcontrast images by direct visual control (pre/post-Gd), and on the subtracted images (SI) only. Without MT, 36 enhancing lesions were counted on post-Gd, 36 on pre/post-Gd, and 59 on SI; using MT, 69, 52, and 50, respectively. Significant differences were found for pre/post-Gd without MT vs SI without MT ( p=0.028) and vs pre/post-Gd with MT ( p=0.012) as well as for pre/post-Gd with MT vs post-Gd with MT ( p=0.028). With pre/post-Gd, MT allowed the detection of 1.6 enhancing lesions per patient more than without MT. Whereas the SI without MT allow the detection of an increased number of enhancing lesions, SI with MT do not. An off-site final assessment allowed calculation of sensitivity and positive predictive value as follows: without MT were 63 and 94% (post-Gd), 67 and 100% (pre/post-Gd), 96 and 88% (SI); and with MT were 93 and 73% (post-Gd), 96 and 100% (pre/post-Gd), 91 and 98% (SI), respectively. Thus, SI seem to increase the sensitivity without MT; moreover, they could be used to correct the pseudoenhancement that impair post-Gd images with MT.

The aim of this study was to evaluate coronary artery stents with MR. Thirty-eight patients underwent MR imaging 48.1 +/- 6.6 days (range 38-60 days) after placement of 47 coronary stents of 11 different types, using navigator echo (NE) and cine gradient-echo (GE) techniques. For both sequences the low signal artifact was used to localize the stent, whereas the flow-related high signal before and distal to the stent was considered as a patency sign. Exercise electrocardiographic test (EET) had been performed 1-7 days before MR. No adverse event with possible relation to the MR examination was observed. All the stents were recognized as signal void with GE, and all but one with NE. Of the 2 patients with positive EET, the first one, with a stent on the left anterior descending coronary artery, presented low signal distal to the stent at both MR sequences, suggesting dysfunction [60% stenosis at conventional coronary angiography (CCA)]; the second one, with two sequential stents on the right coronary artery, presented lack of signal distal to the stents at both MR sequences, suggesting occlusion (97% stenosis at CCA). For the 44 remaining stents in 36 patients with negative EET, MR high signal before and distal to the stent suggested patency at both sequences. MR seems to be a safe and promising technique for non-invasive evaluation of coronary stents.