MR imaging of the foot and ankle: patterns of bone marrow signal abnormalities

Abstract.: Diagnosis of marrow disorders of the foot and ankle is among the more challenging aspects of MR interpretation. Evaluation of normal and abnormal bone marrow with regard to pattern, distribution, and signal characteristics on different sequences often allows a specific diagnosis. This pictorial review illustrates MR imaging findings of normal variants of bone marrow of the foot and ankle, and the varied responses of bone marrow to trauma, stress, or diseas

Muskuloskeletal MR imaging at 3.0 T: current status and future perspectives

Magnetic resonance (MR) imaging has become an important diagnostic tool in evaluation of the musculoskeletal system. While most examinations are currently performed at magnetic field strengths of 1.5T or lower, whole-body MR systems operating at 3.0T have recently become available for clinical use. The higher field strengths promise various benefits, including increased signal-to-noise ratios, enhanced T2* contrast, increased chemical shift resolution, and most likely a better diagnostic performance in various applications. However, the changed T1, T2, and T2* relaxation times, the increased resonance-frequency differences caused by susceptibility and chemical-shift differences, and the increased absorption of radiofrequency (RF) energy by the tissues pose new challenges and/or offer new opportunities for imaging at 3.0T compared to 1.5T. Some of these issues have been successfully addressed only in the very recent past. This review discusses technical aspects of 3.0T imaging as far as they have an impact on clinical routine. An overview of the current data is presented, with a focus on areas where 3.0T promises equivalent or improved performance compared 1.5T or lower field strength

Pulmonary hemorrhage: Imaging with a new magnetic resonance blood pool agent in conjunction with breathheld three-dimensional magnetic resonance angiography

Purpose: To describe the three-dimensional magnetic resonance angiography (3D MRA) imaging appearance of the pulmonary arteries following administration of a superparamagnetic iron oxide blood pool agent to human volunteers, and to demonstrate in an animal model (pigs) how this technique can be used to detect pulmonary parenchymal hemorrhage. Methods: Two volunteers were examined following the intravenous administration of a superparamagnetic iron oxide blood pool agent (NC100150 Injection, Nycomed Amersham Imaging, Wayne, PA, USA). T1-weighted 3D gradient recalled echo (GRE) image sets (TR/TE 5.1/1.4 msec, flip angle 30°) were acquired breathheld over 24 sec. To assess the detectability of pulmonary bleeding with intravascular MR contrast, pulmonary parenchymal injuries were created in two animals under general anesthesia, and fast T1-weighted 3D GRE image sets collected before and after the injury. Results: Administration of the intravascular contrast in the two volunteers resulted in selective enhancement of the pulmonary vasculature permitting complete visualization and excellent delineation of central, segmental, and subsegmental arteries. Following iatrogenic injury in the two animals, pulmonary hemorrhage was readily detected on the 3D image sets. Conclusion: The data presented illustrate that ultrafast 3D GRE MR imaging in conjunction with an intravenously administered intravascular blood pool agent can be used to perform high-quality pulmonary MRA as well as to detect pulmonary hemorrhag

Upper extremity peripheral neuropathies: role and impact of MR imaging on patient management

To investigate the role of MR imaging (MRI) in the evaluation of peripheral nerve lesions of the upper extremities and to assess its impact on the patient management. Fifty-one patients with clinical evidence of radial, median, and/or ulnar nerve lesions and unclear or ambiguous clinical findings had MRI of the upper extremity at 1.5T. MR images and clinical data were reviewed by two blinded radiologists and a group of three clinical experts, respectively, with regard to radial, median, and/or ulnar nerve, as well as muscle abnormalities. MRI and clinical findings were correlated using Spearman's (p) rank correlation test. The impact of MRI on patient management was assessed by the group of experts and ranked as "major,” "moderate,” or "no” impact. The correlation of MRI and clinical findings was moderate for the assessment of the median/radial nerve and muscles (p = 0.51/0.51/0.63, respectively) and weak for the ulnar nerve (p = 0.40). The impact of MRI on patient management was assessed as "major” in 24/51 (47%), "moderate” in 19/51 (37%), and "no” in 8/51 (16%) patients. MRI in patients with upper extremity peripheral neuropathies and unclear or ambiguous clinical findings substantially influences the patient managemen

Dynamic pelvic floor imaging: MRI techniques and imaging parameters

Magnetic resonance imaging (MRI) is an excellent tool to understand the complex anatomy of the pelvic floor and to assess pelvic floor disorders. MRI enables static and dynamic imaging of the pelvic floor. Using static T2-weighted sequences the morphology of the pelvic floor can be visualized in great detail. A rapid half-Fourier T2-weighted, balanced steady state free precession, or gradient-recalled echo sequence are used to obtain sagittal images while the patient is at rest, during pelvic squeeze, during pelvic strain and to document the evacuation process. On these images the radiologist identifies the pubococcygeal line (PCL) (which represents the level of the pelvic floor). In normal findings, the base of the anterior and the middle compartment are above the PCL at rest, and the pelvic floor elevates during contraction. During straining the pelvic floor muscles should relax and the pelvic floor descends normally less than 3cm below the PCL. Pelvic floor MRI based on the static and dynamic MRI sequences allows for the detection and characterization of a vast array of morphologic and functional pelvic floor disorders. In this review, we focus on technical aspects of static and dynamic pelvic floor MR

Magnet Resonance Angiography versus Conventional Angiography for the Planning of Reconstructive Surgeries

Summary:: Assessing the vascular status and anatomy of the lower extremity is of crucial importance when planning the coverage of a tissue defect with a free flap. The standard techniques comprise the clinical examination, Doppler ultrasound and Doppler sonography for healthy patients without suspected direct trauma to the vascular system, and conventional digital subtraction angiography (DSA), respectively, in case of traumatized vessels or patients with peripheral arterial obstructive disease. Materials:: We have conducted a prospective study for the comparison of the magnetic resonance angiography (MRA) to the conventional DSA. Fourteen patients were examined presurgically by means of both a conventional DSA and an MRA before undergoing planned microvascular coverage of tissue defects of the lower extremity. The surgeon, based on a questionnaire, assessed and compared both examination results according to their information content. Furthermore, the presurgically planned level and localization of the vascular anastomoses and the intraoperative findings were compared postoperatively. Results:: The MRA examination yielded sufficient information on the vascular anatomy to enable the surgeon to carry out a detailed presurgical planning. Additionally, the use of MRA showed clear advantages with regard to both patient and user comfort. Conclusion:: Taking into account the advantages for the assessment of vessels using MRA, in particular when considering the impact of the frequently varying vascular anatomy of the lower leg on reconstructive surgery, as well as the significantly lower morbidity rate of the examination itself, then the MRA must be regarded as a safe alternative to the DS

Double-contrast magnetic resonance imaging of hepatocellular carcinoma after transarterial chemoembolization

Background: The purpose of this study was to assess the accuracy of double-contrast magnetic resonance (MR) imaging for the treatment response evaluation of hepatocellular carcinoma (HCC) in cirrhotic liver after transarterial chemoembolization (TACE). Methods: Twenty-two patients with 30 HCC nodules treated by TACE underwent double-contrast MR imaging 1month after treatment. MR images were obtained before and after the sequential administration of superparamagnetic iron oxide (SPIO) and gadopentetate dimeglumine contrast agent within the same imaging session. Two observers retrospectively assessed all treated nodules for evidence of residual viable tumor after TACE. The diagnostic performance of gadolinium-enhanced, SPIO-enhanced, and double-contrast enhanced images was calculated. Histopathological and angiographical findings served as standard of reference. Receiver operating characteristic curves and areas under the curves (A z) were calculated. Results: Double-contrast technique (A z=0.95) was significantly (p=0.036) more accurate than SPIO-enhanced technique (A z=0.92) and gadolinium-enhanced technique (p=0.005) (A z=0.81) in viable tumor detection after TACE. Double-contrast technique was significantly more sensitive (92%) than SPIO-enhanced technique (80%) and gadolinium-enhanced technique (68%). Kappa values for interobserver agreement ranged from 0.67 to 0.87 and were significantly different from zero (all p<0.001). Conclusions: Compared to gadolinium-enhanced and SPIO-enhanced techniques, double-contrast technique significantly improves the detection of viable tumor in HCC after TAC

Low-dose intranasal versus oral midazolam for routine body MRI of claustrophobic patients

The purpose of this study was to assess prospectively the potential of low-dose intranasal midazolam compared to oral midazolam in claustrophobic patients undergoing routine body magnetic resonance imaging (MRI). Seventy-two adult claustrophobic patients referred for body MRI were randomly assigned to one of two treatment groups (TG1 and TG2). The 36 patients of TG1 received 7.5mg midazolam orally 15min before MRI, whereas the 36 patients of TG2 received one (or, if necessary, two) pumps of a midazolam nasal spray into each nostril immediately prior to MRI (in total, 1 or 2mg). Patients' tolerance, anxiety and sedation were assessed using a questionnaire and a visual analogue scale immediately before and after MRI. Image quality was evaluated using a five-point-scale. In TG1, 18/36 MRI examinations (50%) had to be cancelled, the reduction of anxiety was insufficient in 12/18 remaining patients (67%). In TG2, 35/36 MRI examinations (97%) were completed successfully, without relevant adverse effects. MRI image quality was rated higher among patients of TG2 compared to TG1 (p<0.001). Low-dose intranasal midazolam is an effective and patient-friendly solution to overcome anxiety in claustrophobic patients in a broad spectrum of body MRI. Its anxiolytic effect is superior to that of the orally administrated for

Contrast-enhanced MR cholangiography with Gd-EOB-DTPA in patients with liver cirrhosis: visualization of the biliary ducts in comparison with patients with normal liver parenchyma

The purpose of this study was to assess the quality of biliary duct visualization using Gd-EOB-DTPA-enhanced magnetic resonance cholangiography (EOB-MRC) in patients with liver cirrhosis. Forty adult patients with liver cirrhosis (cirrhosis group) and 20 adult individuals with normal liver parenchyma (control group) underwent EOB-MRC using T1-weighted GRE imaging up to 180min after Gd-EOB-DTPA administration. Two observers assessed the visualization of each biliary structure and the overall anatomical visualization of the biliary tree. Child-Pugh, MELD score and laboratory findings were compared. The grade of visualization for each evaluated biliary structure was statistically different in the two groups (P = 0.004 to <0.001). The overall EOB-MRC quality was rated as sufficient for anatomical visualization of the biliary tree in all individuals of the control group 20min after Gd-EOB-DTPA application, but in only 16/40 patients (40%) of the cirrhosis group within 30min after application. Analysis of the ROC curves revealed that the cut-off values, for non-sufficient visualization of the biliary tree 20min after Gd-EOB-DTPA application, were MELD scores ≥11 and total serum bilirubin levels ≥30 μmol/l. Consecutively, EOB-MRC in patients with liver cirrhosis resulted in a decreased or even non-visualization of the biliary tree in a substantial percentage of patient