Renal artery stenosis evaluation: diagnostic performance of gadobenate dimeglumine-enhanced MR angiography--comparison with DSA.

PURPOSE: To prospectively determine diagnostic performance and safety of contrast material-enhanced (CE) magnetic resonance (MR) angiography with 0.1 mmol per kilogram of body weight gadobenate dimeglumine for depiction of significant steno-occlusive disease (> or =51% stenosis) of renal arteries, with digital subtraction angiography (DSA) as reference standard. MATERIALS AND METHODS: This multicenter study was approved by local institutional review boards; all patients provided written informed consent. Patient enrollment and examination at centers in the United States complied with HIPAA. Two hundred ninety-three patients (154 men, 139 women; mean age, 61.0 years) with severe hypertension (82.2%), progressive renal failure (11.3%), and suspected renal artery stenosis (6.5%) underwent CE MR angiography with three-dimensional spoiled gradient-echo sequences after administration of 0.1 mmol/kg gadobenate dimeglumine at 2 mL/sec. Anteroposterior and oblique DSA was performed in 268 (91.5%) patients. Three independent blinded reviewers evaluated CE MR angiographic images. Sensitivity, specificity, and accuracy of CE MR angiography for detection of significant steno-occlusive disease (> or =51% vessel lumen narrowing) were determined at segment (main renal artery) and patient levels. Positive and negative predictive values and positive and negative likelihood ratios were determined. Interobserver agreement was analyzed with generalized kappa statistics. A safety evaluation (clinical examination, electrocardiogram, blood and urine analysis, monitoring for adverse events) was performed. RESULTS: Of 268 patients, 178 who were evaluated with MR angiography and DSA had significant steno-occlusive disease of renal arteries at DSA. Sensitivity, specificity, and accuracy of CE MR angiography for detection of 51% or greater stenosis or occlusion were 60.1%-84.1%, 89.4%-94.7%, and 80.4%-86.9%, respectively, at segment level. Similar values were obtained for predictive values and for patient-level analyses. Few CE MR angiographic examinations (1.9%-2.8%) were technically inadequate. Interobserver agreement for detection of significant steno-occlusive disease was good (79.9% agreement; kappa = 0.69). No safety concerns were noted. CONCLUSION: CE MR angiography performed with 0.1 mmol/kg gadobenate dimeglumine, compared with DSA, is safe and provides good sensitivity, specificity, and accuracy for detection of significant renal artery steno-occlusive disease.

MR imaging evaluation of the postoperative knee.

The increased number of patients undergoing arthroscopy or surgery of the knee for sports medicine injuries is leading to increased numbers of patients who require imaging after surgery because of failure to improve, recurrent symptoms, or new injury. As in preoperative patients, magnetic resonance (MR) imaging is the most valuable imaging method for postoperative evaluation of the knee. Surgical changes increase the difficulty of diagnosis of abnormalities in the knee with MR imaging. MR arthrography with direct intraarticular injection of contrast material can help improve evaluation of the postoperative meniscus and possibly help improve evaluation of anterior cruciate ligament grafts in patients after surgery. Recognition of the normal postoperative MR imaging appearance of the structures in the knee and of abnormalities is essential to accurate MR imaging evaluation of these patients.

Magnetic resonance diagnosis of meniscal tears in patients with acute anterior cruciate ligament tears.

OBJECTIVE: To evaluate the accuracy of magnetic resonance imaging in the diagnosis of meniscal tear in patients with acute anterior cruciate ligament tears. METHODS: Magnetic resonance images obtained from 41 patients imaged within 6 weeks of injury who had acute anterior cruciate ligament tears identified at arthroscopy were retrospectively reviewed for meniscal tear. RESULTS: With MR imaging the sensitivity, specificity and accuracy for diagnosing meniscal tears in the presence of acute anterior cruciate ligament tears were 71%, 93%, and 88%; for the lateral meniscal tears were 57%, 100% and 85%; and for the medial meniscal tears were 100%, 88%, 90%. All false negative cases (n = 6) involved the posterior horn of the lateral meniscus. CONCLUSION: In the presence of acute anterior cruciate ligament tears, MRI imaging has relatively low sensitivity for detecting meniscal tears due to missed tears in the lateral meniscus.

Sacroiliitis in patients with ankylosing spondylitis: association of MR findings with disease activity.

The purpose of this study was to determine whether MR findings can correlate disease activity as measured by laboratory markers in ankylosing spondylitis. MR images in 19 patients with ankylosing spondylitis were retrospectively analyzed for cartilage abnormality, periarticular erosion, synovial enhancement, and bone marrow edema. Each MR finding was correlated with laboratory inflammatory markers (erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)) and the sum of ESR + CRP. Synovial enhancement showed a significant correlation with ESR (r=0.58; p<0.01) and increased activity at bone scan (r=0.74; p<0.005), whereas there was no significant correlation with CRP. A significant correlation was found between ESR + CRP and synovial enhancement (r=0.54; p<0.05). Synovial enhancement was more common when ESR + CRP was greater than 30 (p<0.05). In conclusion, synovial enhancement at MR imaging could correlate disease activity as measured by laboratory inflammatory markers in ankylosing spondylitis.

What's new in cartilage?

Magnetic resonance (MR) imaging of articular cartilage is important in evaluation of new surgical and pharmacologic treatments for cartilage damage. Many techniques exist for MR imaging of articular cartilage. Standard techniques for morphologic imaging of cartilage include fast spin-echo and spoiled gradient-echo imaging. These methods provide high-resolution morphologic images of cartilage but are time-consuming in the clinical setting. New methods for faster or higher-resolution morphologic imaging include techniques based on steady-state free precession imaging. These fast techniques will allow detailed evaluation of cartilage in the routine clinical setting. There are also several MR imaging methods that may provide information about the structure and physiology of cartilage. Physiologic imaging may allow detailed evaluation of the glycosaminoglycan matrix or collagen network of articular cartilage and may be the most sensitive method for detection of early changes. With the development of new therapies for osteoarthritis and cartilage injury, MR imaging of articular cartilage is of increasing clinical importance. MR imaging will play an important role in evaluation of the effectiveness of these therapies.

MR arthrography of anterior cruciate ligament reconstruction grafts.

OBJECTIVE: Our objective was to determine the accuracy of MR arthrography for identification of tears of anterior cruciate ligament reconstruction grafts and for detection of localized anterior arthrofibrosis and impingement. MATERIALS AND METHODS: We retrospectively identified 27 patients (mean age, 31 years; range, 18-45 years) with anterior cruciate ligament reconstruction who had undergone MR arthrography followed by arthroscopy within 1 year. Three radiologists independently reviewed the MR arthrograms for the presence or absence of graft tear, localized anterior arthrofibrosis, and impingement. RESULTS: Graft tears were identified with 100% sensitivity by all three reviewers with specificities of 100%, 89%, and 94%. Localized anterior arthrofibrosis was identified with 100% sensitivity by all reviewers, with specificities of 79%, 71%, and 38%. Impingement was detected with sensitivities and specificities of 83% and 100%, 83% and 52%, and 33% and 90% by the three reviewers, respectively. Interobserver agreement was almost perfect for detection of graft tear (kappa = 0.83, 0.92, and 0.83), was fair to moderate for detection of localized anterior arthrofibrosis (kappa = 0.50, 0.32, and 0.22), and was slight to fair for detection of impingement (kappa = 0.40, 0.08, and 0.35). CONCLUSION: MR arthrography can accurately depict the presence of anterior cruciate ligament graft tears. Localized anterior arthrofibrosis and graft impingement were less accurately detected and showed greater observer variability.

Discrimination of metastatic from acute osteoporotic compression spinal fractures with MR imaging.

A study was performed to determine which magnetic resonance (MR) imaging findings are useful in discrimination between metastatic compression fractures and acute osteoporotic compression fractures of the spine. The MR imaging findings in 27 patients with metastatic compression fractures and 55 patients with acute osteoporotic compression fractures were compared by using the chi(2) test. MR imaging findings suggestive of metastatic compression fractures were as follows: a convex posterior border of the vertebral body, abnormal signal intensity of the pedicle or posterior element, an epidural mass, an encasing epidural mass, a focal paraspinal mass, and other spinal metastases. MR imaging findings suggestive of acute osteoporotic compression fractures were as follows: a low-signal-intensity band on T1- and T2-weighted images, spared normal bone marrow signal intensity of the vertebral body, retropulsion of a posterior bone fragment, and multiple compression fractures. The signal intensity on fast spin-echo T2-weighted images obtained without fat suppression played little role in distinguishing between metastatic compression fractures and acute osteoporotic compression fractures.

Meniscal tear configurations: categorization with MR imaging.

OBJECTIVE: The purpose of this study was to evaluate the accuracy of MR imaging for categorizing the configuration of meniscal tears of the knee. MATERIALS AND METHODS: Fast spin-echo MR images obtained at 1.5 T from 110 patients who had meniscal tears identified at arthroscopy were retrospectively and independently classified by two reviewers into five configurations: horizontal, longitudinal, radial, oblique, and complex. MR imaging categorization was compared with arthroscopic results as the standard of reference. Data were also analyzed with longitudinal and oblique tears combined because these usually are reparable, and with horizontal, radial, and complex tears combined because these usually are not reparable. Interobserver and intraobserver agreements were calculated using kappa coefficients. RESULTS: At arthroscopy, meniscal tears were categorized as horizontal (n = 44), longitudinal (n = 34), complex (n = 22), radial (n = 11), and oblique (n = 5). Sensitivity, specificity, and accuracy of each reviewer for the reparable tears were 82%, 92%, and 89%; and 59%, 97%, and 84%, respectively. Interobserver agreements were fair between reviewer 1 and the first and second interpretations of reviewer 2 (kappa = 0.25, p < 0.005; and kappa = 0.21, p < 0.05, respectively). Intraobserver agreement was substantial (kappa = 0.71, p < 0.001). CONCLUSION: MR imaging was accurate for predicting reparable meniscal tears and was sensitive for the determination of nonreparable tears.

MR imaging of chondral and osteochondral injuries of the knee.

MRT can detect accurately articular cartilage injuries and associated bone, meniscal, and ligament injuries. Identification and characterization of articular cartilage abnormalities is important for determination of prognosis, therapeutic decision making, and preoperative planning.

Early postexercise muscle glycogen recovery is enhanced with a carbohydrate-protein supplement.

In the present study, we tested the hypothesis that a carbohydrate-protein (CHO-Pro) supplement would be more effective in the replenishment of muscle glycogen after exercise compared with a carbohydrate supplement of equal carbohydrate content (LCHO) or caloric equivalency (HCHO). After 2.5 +/- 0.1 h of intense cycling to deplete the muscle glycogen stores, subjects (n = 7) received, using a rank-ordered design, a CHO-Pro (80 g CHO, 28 g Pro, 6 g fat), LCHO (80 g CHO, 6 g fat), or HCHO (108 g CHO, 6 g fat) supplement immediately after exercise (10 min) and 2 h postexercise. Before exercise and during 4 h of recovery, muscle glycogen of the vastus lateralis was determined periodically by nuclear magnetic resonance spectroscopy. Exercise significantly reduced the muscle glycogen stores (final concentrations: 40.9 +/- 5.9 mmol/l CHO-Pro, 41.9 +/- 5.7 mmol/l HCHO, 40.7 +/- 5.0 mmol/l LCHO). After 240 min of recovery, muscle glycogen was significantly greater for the CHO-Pro treatment (88.8 +/- 4.4 mmol/l) when compared with the LCHO (70.0 +/- 4.0 mmol/l; P = 0.004) and HCHO (75.5 +/- 2.8 mmol/l; P = 0.013) treatments. Glycogen storage did not differ significantly between the LCHO and HCHO treatments. There were no significant differences in the plasma insulin responses among treatments, although plasma glucose was significantly lower during the CHO-Pro treatment. These results suggest that a CHO-Pro supplement is more effective for the rapid replenishment of muscle glycogen after exercise than a CHO supplement of equal CHO or caloric content.

Grade 2C signal in the meniscus [correction of mensicus] on MR imaging of the knee.

OBJECTIVE: The objective of our study was to evaluate the clinical significance of grade 2C meniscal [corrected] signal (an extensive triangular or wedge-shaped signal that does not reach the surface on more than one image) on MR imaging of the knee. MATERIALS AND METHODS: Review of 1106 MR imaging reports over 2 years revealed 88 patients with menisci described as containing triangular, wedge-shaped, extensive, or grade 2C signal. Image review by consensus of two radiologists found 34 menisci in 29 patients that fit criteria for grade 2C signal. Seven menisci containing grade 2C signal were evaluated with arthroscopy. An additional three patients with grade 2C meniscal signal with arthroscopic correlation were identified from 4 previous years. RESULTS: Prevalence of grade 2C signal was 1.5% (34/2212 menisci). Seven (21%) of these 34 menisci had subsequent arthroscopy and three of these had meniscal tears. Including the three additional menisci with grade 2C signal from 4 previous years, five (50%) of 10 menisci with grade 2C signal were torn at arthroscopy. No difference was noted between torn and intact menisci in the number of images with grade 2C signal. In patients with tears, the range was three to 10 images (mean, 6.6 images) compared with a range of two to 10 images (mean, 6.6 images) in patients without tears. The maximal percentage of area of abnormal signal in patients with tears ranged from 70% to 90% (mean, 80%) compared with a range of 60-90% (mean, 82%) in patients without tears. The patient age range was 23-64 years (mean, 47 years) in patients with tears and 16-67 years (mean, 47 years) in patients without tears. CONCLUSION: Grade 2C meniscal signal has a low incidence. Although half of patients with symptoms meriting arthroscopy have tears, most patients with grade 2C signal are not treated with arthroscopy.

Pelvic lymph node visualization with MR imaging using local administration of ultra-small superparamagnetic iron oxide contrast.

PURPOSE: To determine if interstitial injection of iron oxide particles improves visualization of pelvic lymph nodes at magnetic resonance imaging (MRI) and to determine the effect of injection site on location of visualized nodes. MATERIALS AND METHODS: In nine healthy volunteers, ferumoxtran-10 iron oxide (0.28 mg iron per kg) was injected into the anterior thigh (three subjects) or perianal (three subjects) or periprostatic tissues (three subjects). MRI at 1.5 T was performed before injection and one, three, and seven days after injection. RESULTS: The mean of 30 nodes seen post-injection was greater than the mean of 5.8 seen pre-injection (P < 0.001). After thigh injection, a mean of three internal vs. 36 external nodes were seen. Compared with thigh injection, there was a higher fraction of internal nodes with perianal (mean of nine internal vs. 14 external, P < 0.001) and periprostatic injection (mean of 11 internal vs. five external, P < 0.001). More nodes were seen with gradient-echo sequences than with other sequences (P < 0.001). CONCLUSION: Interstitial injection of iron oxide particles increases visualization of pelvic lymph nodes. Perianal and periprostatic injection increases the number of internal pelvic lymph nodes seen compared with thigh injection.