Superior labral anterior posterior (SLAP) lesions of the glenoid labrum: reliability and accuracy of MR arthrography for diagnosis

PURPOSE: To determine the reliability and accuracy of magnetic resonance (MR) arthrography for the diagnosis of superior labral anterior posterior (SLAP) tears. MATERIALS AND METHODS: The MR arthrograms in 80 patients who underwent arthroscopy and MR arthrography during a 54-month period were retrospectively reviewed. MR arthrograms were independently scored by three observers for the presence and type of SLAP lesion. Type I SLAP lesions were regarded as negative as they most often are not clinically relevant. Interobserver agreement for detection of SLAP lesions was calculated by using kappa coefficients. The differences in areas under the receiver operating characteristic (ROC) curves were assessed with a univariate z score test. RESULTS: At arthroscopy, there were 25 SLAP tears: type II (n = 22), type III (n = 2), and type IV (n = 1). Sensitivity, specificity, and accuracy of each reader were 92%, 84%, and 86%; 92%, 82%, and 85%; and 84%, 69%, and 74%, respectively. Interobserver agreement for SLAP tears was substantial (kappa = 0.77) to moderate (kappa = 0.52, kappa = 0.44). The areas under the ROC curves for each reader were 0.94, 0.93, and 0.83, which were not significantly different. CONCLUSION: MR arthrography of the shoulder is reliable and accurate for detection of SLAP tears.     

半月板损伤及撕裂的MRI与关节镜或手术对照研究

目的评价不同观察者对膝关节半月板损伤MRI诊断一致性及撕裂形态学MRI诊断分级的准确性。方法由两位有经验的影像科医生回顾性对82例82个疑有半月板损伤的MRI图像,所得两次诊断结果进行Kappa统计量分析。本研究中用关节镜或手术结果作为诊断参考标准,确诊撕裂的内侧半月板有29例,外侧半月板有40例,分别分析内外侧半月板经参考标准确诊的撕裂的两次诊断的诊断价值。结果对内侧半月板Kappa值为0.71,对外侧半月板Kappa值为0.65,两次诊断均有好的诊断一致性。对内侧半月板可修复撕裂两次诊断的灵敏性、特异性、准确性分别为95%、38%、79%;100%、38%、83%。对外侧半月板可修复撕裂两次诊断的灵敏性、特异性、准确性分别为93%、65%、75%;93%、77%、93%。结论MRI两次诊断对内外侧半月板诊断一致性良好,对内外侧半月板可修复撕裂准确性、灵敏度较高,对外侧半月板可修复撕裂特异度较高。     

MR findings of meniscal extrusion correlated with arthroscopy

PURPOSE: To correlate MR exams showing meniscal extrusions >3 mm beyond the tibial margin with arthroscopic findings. Meniscal extrusion (> 3 mm extension beyond the tibial margin) has been described on previous studies as having a high index of association with meniscal root tears. These previous studies were limited by a lack of exact arthroscopic correlation. We also assessed the prevalence of meniscal root tears on MR examinations without meniscal extrusions. MATERIALS AND METHODS: A retrospective review was performed of 300 consecutive knee MR exams of patients who went on to arthroscopy. All patients had a complete MR exam performed on a 3T GE MR scanner. MR exams were reviewed for medial meniscal extrusion > 3 mm from the tibial margin. The exams with medial meniscal extrusion were reviewed for meniscal tears on MR exam. The exams without meniscal extrusion were reviewed for meniscal root tears. Results were subsequently correlated with arthroscopy. RESULTS: Of the 300 MR exams, 42 demonstrated medial meniscal extrusion >3 mm from the tibial margin. Of these 42 patients, 34 had meniscal degeneration, complex tear, or a large radial tear near to or involving the meniscal root on MR examination. A total of 33 of these tears described on MR exam were seen at arthroscopy. A total of 24 of these tears were root tears, seven were complex tears, and two had severe meniscal degeneration. There was one root tear described on MR exam that was not seen on arthroscopy. Eight of the 42 patients had no meniscal tear demonstrated on MR examination or arthroscopy. All eight of these patients were > or = 50 years old. There were two meniscal root tears on both MR exam and at arthroscopy in the 258 patients without meniscal extrusion on MR exam. CONCLUSION: There is a high prevalence of meniscal root tears in patients with meniscal extrusion on MR exam. Meniscal root tears are uncommon in patients without meniscal extrusion on MR exam. There may be a subset of patients in which the meniscal root is stretched rather than torn. Medial meniscal extrusion in patients > 50 years old may be associated with a meniscal "stretch" injury due to degeneration of the meniscus without a meniscal tear detectable on arthroscopy. These menisci may have increased laxity due to compromised meniscal collagen fibers. This may predispose the patient to premature osteoarthritis.     

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.     

Medial meniscus extrusion on knee MRI: is extent associated with severity of degeneration or type of tear?

OBJECTIVE: The meniscus is considered "extruded" when it extends beyond the tibial margin. We hypothesize that severe degeneration, large radial tears, complex tears, and tears involving the meniscal root would alter meniscal stability and cause more substantial extrusion. MATERIALS AND METHODS: The knee MRI database at Thomas Jefferson University Hospital was searched for reports describing meniscal extrusion; MR images were reviewed retrospectively. On mid coronal images, extrusion of the medial meniscus was quantified in millimeters. A separate, independent review of the meniscus evaluated degeneration severity and tear (type and extent). Radial tears were divided into those involving more (large) or less (small) than 50% of the meniscal width. Tears that involved the "root" at the tibial spine were recorded. Chi-square analysis compared these findings with extrusion extent, divided into minor ( 3 mm) extrusion. RESULTS: One hundred five knees were reviewed (12 men and 93 women; age range, 34-83 years; mean age, 56 years). Distribution of medial meniscus extrusion was 2 mm (n = 17), 3 mm (n = 17), 4 mm (n = 27), 5 mm (n = 14), 6 mm (n = 16), and 7-10 mm (n = 14). Mild, moderate, or marked degeneration was seen in 47%, 26%, and 27% with minor extrusion, respectively, and in 17%, 41%, and 42% with major extrusion, respectively (p = 0.003). Tears were seen in 59% (20/34) with minor extrusion versus 89% (63/71) with major extrusion (p = 0.001). Tears involved one third, two thirds, or all of the meniscus in 75%, 25%, or 0%, respectively, with minor extrusion and 46%, 40%, or 14% with major extrusion, respectively (p = 0.014). Longitudinal (nonradial) and horizontal tears were not associated with extent of extrusion (p = 1.0). Oblique tears were significantly associated with minor extrusion (minor, 26% [9/34]; major, 4% [3/71]; p = 0.003). Radial tears were seen in 9% (3/34) with minor extrusion versus 21% (15/71) with major extrusion (p = 0.20). All three radial tears with minor extrusion were small; conversely, 87% (13/15) of radial tears with major extrusion were large (p = 0.019). Complex tears were seen in 18% (6/34) with minor extrusion versus 59% (42/71) with major extrusion (p < 0.001). Tears involving the meniscal root were seen in 3% (1/34) with minor extrusion and 42% (30/71) with major extrusion (p < 0.001). CONCLUSION: Substantial medial meniscus extrusion (> 3 mm) is associated with severe meniscal degeneration, extensive tear, complex tear, large radial tear, and tear involving the meniscal root.     

Characteristics of displaceable and nondisplaceable meniscal tears at kinematic MR imaging of the knee

PURPOSE: To prospectively determine if kinematic magnetic resonance (MR) imaging of the knee may demonstrate displacement of menisci with tears and, if so, to characterize displaceable and nondisplaceable meniscal tears. MATERIALS AND METHODS: The study was approved by the hospital's review board, and informed consent was obtained. Forty-two patients (30 men, 12 women; mean age, 36.9 years) with 43 arthroscopically documented meniscal tears visible at 1.5-T MR imaging underwent kinematic MR imaging with an open-configuration 0.5-T MR imager with their knees in supine neutral, supine with 90 degrees flexion and external or internal rotation, and upright weight-bearing positions. Analysis of meniscal movement was performed in different knee positions in the coronal MR imaging plane. Meniscal displacement--that is, meniscal movement of 3 mm or more (in the medial direction for the medial meniscus, in the lateral direction for the lateral meniscus)--was compared with the patient's pain level as assessed with a visual analog scale by using analysis of variance. RESULTS: Between the different knee positions, meniscal displacement of 3 mm or more (displaceable meniscal tears) was noted in 18 (42%) of 43 menisci with tears. Simultaneous occurrence of grade II or III ipsilateral collateral ligament lesions was present in all 18 displaceable meniscal tears, whereas a normal-appearing collateral ligament or collateral ligament lesion (grade I) was present in 22 of 25 nondisplaceable tears (P < .05). Displaced menisci most commonly had complex, radial, or longitudinal tear configurations (16 of 18, 89%). Patients with displaceable meniscal tears had significantly more pain than did patients with nondisplaceable meniscal tears (P < .001), independent of the concomitant knee abnormalities. CONCLUSION: Displaceable meniscal tears usually have longitudinal, radial, or complex configurations; such tears are associated with substantial ipsilateral collateral ligament lesions and pain.     

Effect of chondrocalcinosis on the MR imaging of knee menisci

OBJECTIVE: Our goal was to determine the influence of chondrocalcinosis on MR imaging in the detection of meniscal tears. MATERIALS AND METHODS: A retrospective review was performed of knee MR imaging and arthroscopy records from two university hospitals between 1996 and 1998. Seventy individuals had radiographic evidence of chondrocalcinosis and underwent knee MR imaging. Thirty-seven of these individuals had undergone arthroscopy for further evaluation of their symptoms. MR imaging sensitivity and specificity in the detection of medial and lateral meniscal tears were calculated in these 37 patients who had radiographic evidence of chondrocalcinosis and in a control group of 34 patients who underwent MR imaging and arthroscopy but did not have knee chondrocalcinosis. RESULTS: In the chondrocalcinosis group, MR imaging sensitivity, specificity, and accuracy for meniscal tear were 78%, 71%, and 78%, respectively, for the lateral meniscus, and 89%, 72%, and 81% for the medial meniscus. The control group showed sensitivity, specificity, and accuracy of 93%, 100%, and 97%, respectively, for the lateral meniscus and 100% in all cases for the medial meniscus. The MR imaging detection of meniscal tears in both the lateral and medial compartments combined is significantly poorer in the presence of chondrocalcinosis (p < 0.005). CONCLUSION: MR imaging sensitivity and specificity for detection of meniscal tear is decreased in the presence of meniscal chondrocalcinosis. Chondrocalcinosis appeared as a high-signal-intensity region on T1-weighted, intermediate-weighted, and inversion recovery sequences. The high signal of chondrocalcinosis on inversion recovery sequence is an interesting observation that to our knowledge has not been previously reported. Radiographic correlation with the MR imaging examination can help prevent overdiagnosing meniscal tears.     

Prevalence of meniscal radial tears of the knee revealed by MRI after surgery

OBJECTIVE: Meniscal resection decreases the ability of the meniscus to evenly distribute forces placed on it. These forces are oriented centrifugally on the meniscus by normal weight-bearing and are distributed by circumferentially oriented fibers. This alteration may predispose the knee to radial tears after surgery. SUBJECTS AND METHODS: One of three musculoskeletal radiologists prospectively interpreted 100 consecutive postoperative MRI examinations of the knee. A prospective MRI report was generated for the referring orthopedic surgeon, and prospective MRI interpretations were correlated with arthroscopic findings (n = 63). MRI examinations on those patients who underwent second-look arthroscopy were retrospectively reviewed by three musculoskeletal radiologists who reached a consensus on the prevalence of new postoperative meniscal radial tears. MRI criteria for radial tear diagnosis were used as outlined by Tuckman et al.: truncation, abnormal morphology, lack of continuity, absence of the meniscus, or any combination of those criteria on one or more MR images. An additional criterion used was abnormal increased signal in that area on T2-weighted images. RESULTS: Thirty-two of the 100 patients had meniscal radial tears on prospective MRI interpretations. In 29 of these 32 patients, second-look arthroscopy confirmed meniscal radial tears in the areas described on the MRI examinations. Five additional radial tears were shown on second-look arthroscopy that were not seen on prospective MRI interpretations. Two of those additional five radial tears were seen on consensus retrospective MRI review. CONCLUSION: In this study, a 32% prevalence of meniscal radial tears in the postoperative knee was present on prospective MRI interpretations as opposed to a reported 14% prevalence in the nonoperated knee. Meniscal resection decreases the ability of the meniscus to evenly distribute forces placed on it. This circumstance may increase the prevalence of meniscal radial tears in the postoperative knee. New meniscal radial tears are common in patients presenting with pain after knee surgery.     

Magnetic resonance imaging findings of surgically proven medial meniscus root tear: tear configuration and associated knee abnormalities

OBJECTIVE: To evaluate magnetic resonance imaging (MRI) findings of medial meniscal root tear and the correlation of medial meniscal root tear with other associated knee abnormalities. METHODS: We retrospectively assessed preoperative magnetic resonance images of 39 patients with arthroscopically confirmed medial meniscal root tear. Magnetic resonance imaging findings were retrospectively reviewed by 2 experienced musculoskeletal radiologists for consensus. We evaluated the configuration of meniscal root tear and the other associated knee abnormalities on MRI for direct correlation with arthroscopic findings. RESULTS: At arthroscopy, there were 36 radial tears and 3 complex tears involving the medial meniscal posterior horn roots. All 36 radial tears could be correctly diagnosed by MRI, with findings showing ghost sign on sagittal images in 100% (36/36), vertical linear defect on coronal images in 100% (36/36), and radial linear defect on axial image in 94% (34/36). However, all 3 complex tears were misdiagnosed as radial tears on MRI. Medial meniscal root tears displayed a strong association with degenerative joint disease in 97% (38/39). Medial meniscal root tears were also found in association with cartilage defects of the medial femoral condyle and medial meniscal extrusions (> or =3 mm) in 89% (34/38) and 67% (26/39), respectively. CONCLUSIONS: Medial meniscal root tears were usually posterior horn root radial tear. A high association with degenerative joint disease, cartilage defects of the medial femoral condyle, and medial meniscal extrusions (>/=3 mm) were also noted.     

Radial meniscal tears: significance, incidence, and MR appearance

OBJECTIVE: The purpose of this study was to assess the prevalence of radial meniscal tears at arthroscopy and the ability of MRI to detect radial tears preoperatively. In addition, the ability of four radiologic signs to detect radial tears was assessed. Those signs are the truncated triangle, cleft, marching cleft, and ghost meniscus signs. MATERIALS AND METHODS: Arthroscopy of the knee was performed by a single orthopedic surgeon on 196 consecutive patients. The surgeon noted each radial tear he encountered. The MR images that were obtained at our institution were reviewed, whereas those patients who were imaged elsewhere were excluded. The preoperative MRI reports were reviewed to assess the ability to prospectively identify radial meniscal tears. In addition, a retrospective analysis of the MRI studies was performed by two radiologists in which four radiologic signs were applied to detect radial tears. RESULTS: Twenty-nine patients (15%) had radial tears at arthroscopy. Eighteen of the 29 patients had their imaging performed at our institution and were selected for review. There were 19 radial tears found at surgery. Seven (37%) of the 19 tears were identified as radial prospectively. Retrospectively, using the four signs for radial tears, reviewers identified 17 (89%) of 19 radial tears. CONCLUSION: A more accurate preoperative diagnosis may be rendered using the four described signs to detect radial tears, thus allowing informative preoperative counseling and consideration of new therapies that are available for radial meniscal repair.     

MR imaging of meniscal cysts: incidence, location, and clinical significance.

OBJECTIVE: The purpose of this study was to determine the incidence of medial versus lateral meniscal cysts as seen on MR imaging. MATERIALS AND METHODS: A total of 2572 knee MR imaging reports were retrospectively reviewed for the presence of meniscal tears and cysts. Two musculoskeletal radiologists reviewed all images with reported cysts. The type and location of meniscal tear and the presence and location of meniscal cysts were recorded. RESULTS: A total of 1402 meniscal tears were reported in 2572 MR examinations (922 [66%] of 1402 in the medial compartment; 480 [34%] of 1402 in the lateral compartment). Meniscal cysts were present in 109 (4%) of 2572 knees. Of the 109 cysts, 72 (66%) were in the medial compartment, and 37 (34%) were in the lateral compartment. Meniscal cysts were found in association with 72 (7.8%) of the 922 medial meniscal tears and 37 (7.7%) of the 480 lateral meniscal tears. Meniscal cysts showed direct contact with an adjacent meniscal tear in 107 (98%) of 109 cases, with the tear showing a horizontal component in 96 (90%) of 107 cases. CONCLUSION: Meniscal cysts occur almost twice as often in the medial compartment as in the lateral compartment. Medial and lateral tears occur with the same frequency. These findings, when viewed in the context of the historical literature on meniscal cysts, suggest that MR imaging detects a greater number of medial meniscal cysts than physical examination or arthroscopy, and that MR imaging can have an important impact on surgical treatment of patients.     

MR accuracy and arthroscopic incidence of meniscal radial tears

OBJECTIVE: A meniscal radial tear is a vertical tear that involves the inner meniscal margin. The tear is most frequent in the middle third of the lateral meniscus and may extend outward in any direction. We report (1) the arthroscopic incidence of radial tears, (2) MR signs that aid in the detection of radial tears and (3) our prospective accuracy in detection of radial tears. DESIGN AND PATIENTS: Three musculoskeletal radiologists prospectively read 200 consecutive MR examinations of the knee that went on to arthroscopy by one orthopedic surgeon. MR images were assessed for location and MR characteristics of radial tears. MR criteria used for diagnosis of a radial tear were those outlined by Tuckman et al.: truncation, abnormal morphology and/or lack of continuity or absence of the meniscus on one or more MR images. An additional criterion used was abnormal increased signal in that area on fat-saturated proton density or T2-weighted coronal and sagittal images. Prospective MR readings were correlated with the arthroscopic findings. RESULTS: Of the 200 consecutive knee arthroscopies, 28 patients had radial tears reported arthroscopically (14% incidence). MR readings prospectively demonstrated 19 of the 28 radial tears (68% sensitivity) when the criteria for diagnosis of a radial tear were truncation or abnormal morphology of the meniscus. With the use of the additional criterion of increased signal in the area of abnormal morphology on fat-saturated T2-weighted or proton density weighted sequences, the prospective sensitivity was 25 of 28 radial tears (89% sensitivity). There were no radial tears described in MR reports that were not demonstrated on arthroscopy (i.e., there were no false positive MR readings of radial tears in these 200 patients). CONCLUSIONS: Radial tears are commonly seen at arthroscopy. There was a 14% incidence in this series of 200 patients who underwent arthroscopy. Prospective detection of radial tears was 68% as compared with arthroscopy when the criteria as outlined by Tuckman et al. were used alone. With the use of the additional criterion of increased signal in the area of abnormal morphology on fat-saturated T2-weighted and proton density weighted sequences, the prospective sensitivity for radial tear detection as compared with arthroscopy was 89% in our series. Fat-saturated proton density and T2-weighted images greatly improve the detection of radial tears as signal intensity changes in radial tears as well as morphologic changes can be utilized for the detection of subtle tears.     

MRI of meniscal lesions: soft-copy (PACS) and hard-copy evaluation versus reviewer experience

OBJECTIVE: The purpose of our study was to compare diagnostic performance, reviewer confidence, and time requirements in the MRI diagnosis of meniscal tears for three types of reviewers and two types of image documentations (PACS vs hard copies). MATERIALS AND METHODS: An experienced musculoskeletal radiologist (reviewer 1), a fellow in musculoskeletal radiology (reviewer 2), and a junior staff member in orthopedic surgery (reviewer 3) evaluated MR images displayed on PACS monitors and hard copies independently and in a blinded fashion with regard to the presence or absence of meniscal tears. Seventy-one patients (mean age, 45.4 years; range, 16-80 years) were consecutively included if they had undergone both MRI of the knee and arthroscopy within 4 months. Arthroscopy was the standard of reference. Evaluation time and the reviewer's confidence in his or her diagnosis (Visual Analogue Scale, possible values of 0-100) were determined. RESULTS: Accuracies, sensitivities, and specificities in diagnosing meniscal tears were 80-87%, 63-85%, and 87-93% for soft copies and 82-85%, 64-76%, and 87-94.0%, respectively, for hard copies. Intrareviewer differences between PACS and hard copies were not significant for any of the three reviewers (McNemar tests). Reviewer 3 was less sensitive but more specific in the diagnosis of meniscal tears than reviewers 1 and 2. This difference was significant for both the PACS and hard copies. The reviewers' confidence in their diagnoses and evaluation times were not significantly different for PACS and hard copies (analysis of variance with Bonferroni post hoc analysis). CONCLUSION: Differences in the diagnostic performance of suspected meniscal tears depend on reviewer experience rather than on the type of documentation.     

膝关节半月板放射状撕裂的MRI表现

目的 探讨MRI对膝关节半月板放射状撕裂的检出能力.方法 回顾性分析1085例经关节镜证实的膝关节半月板损伤中的半月板放射状撕裂107例(9.9%)患者的MRI资料,同时按住院号顺序采用等足巨抽样方法 ,抽取100例经关节镜证实的非放射状撕裂的半月板损伤患者作为对照组.所有患者均经MR检查,观察裂隙征及裂隙行走征、半月板分离征、半月板消失征及小半月板征4种征象,与关节镜结果 比较.结果 (1)107例半月板放射状撕裂患者中,最常见的发生部位是外侧半月板体部(71例,66.4%)和前体交界部(25例,23.4%).(2)107例半月板放射状撕裂中,MRI诊断放射状撕裂102例.100例半月板非放射状撕裂的半月板损伤中,MRI诊断11例为放射状撕裂,MRI诊断半月板放射状撕裂的敏感度、特异度、阳性预测值、阴性预测值分别为95.3%(102/107)、89.0%(89/100)、90.3%(102/113)、94.7%(89/94).(3)裂隙征和半月板分离征出现频率最高,102例中分别出现59例(57.8%)和43例(42.2%),是诊断放射状撕裂最重要的MRI征象.结论 MRI诊断半月板放射状撕裂的准确率较高,是目前术前无创诊断的最佳方法 .     

Meniscal tears with fragments displaced in notch and recesses of knee: MR imaging with arthroscopic comparison

PURPOSE: To retrospectively evaluate magnetic resonance (MR) imaging for the depiction of meniscal tears with partially detached meniscal fragments displaced in the intercondylar notch or in the meniscal recesses of the knee. MATERIALS AND METHODS: The institutional review board required neither its approval nor informed patient consent for the retrospective review of patient data; however, informed patient consent had been obtained before the MR imaging examinations were performed. The presence of meniscal tears with notch and recess fragments was determined at MR imaging and at subsequent arthroscopy in 101 consecutive knees to determine the value of MR imaging for the depiction of these lesions. Initial reports were reviewed to evaluate results of initial interpretations. MR images were retrospectively analyzed to determine the value of several MR image signs for the detection of displaced tears with notch or recess fragments. RESULTS: At arthroscopy, 37 (41%) of 91 torn menisci had partially detached fragments. Twenty-six torn menisci had notch fragments, and 14 had recess fragments; three torn menisci had one notch and one recess fragment each. At initial MR image analysis, 38 (36%) of 105 torn menisci had partially detached fragments. Twenty-eight torn menisci had notch fragments, and 13 had recess fragments; one torn meniscus had two recess fragments, and three torn menisci had one notch and one recess fragment each. At initial analysis, sensitivities and specificities were, respectively, 69% and 94% for detection of tears with notch fragments and 71% and 98% for detection of tears with recess fragments. At retrospective analysis of sagittal MR images, the presence of at least one sign indicative of meniscal tear with a notch fragment had sensitivities and specificities, respectively, of 65% and 78% for observer 1 and 77% and 73% for observer 2. The presence of at least one sign indicative of a meniscal tear with a recess fragment had sensitivities and specificities, respectively, of 64% and 77% for observer 1 and 64% and 76% for observer 2. CONCLUSION: Meniscal tears with notch and recess fragments are frequently seen at arthroscopy and can be depicted at knee MR imaging with moderate sensitivity and high specificity.     

Grading of anterior cruciate ligament injury. Diagnostic efficacy of oblique coronal magnetic resonance imaging of the knee

OBJECTIVE: This study was undertaken to evaluate the diagnostic efficacy of additional oblique coronal magnetic resonance (MR) imaging of the knee for the grading of anterior cruciate ligament (ACL) injury. METHODS: We retrospectively reviewed MR images of the knee in 169 patients. The MR examinations included routine sequences and oblique coronal T2-weighted images, which oriented in parallel to the course of the femoral intercondylar roof. Two independent readers evaluated the status of the ACL by routine knee MR imaging and then by additional oblique coronal imaging. The severity of the ACL injury was graded using a 4-point system from MR images, namely, intact, low-grade partial tear, high-grade partial tear, and complete tear, and results were compared with arthroscopic findings. Weighted kappa statistics were used to analyze the diagnostic accuracy of routine knee MR imaging with and without additional oblique coronal imaging. RESULTS: The weighted kappa scores (kappaws) were 0.752 (reader 1) and 0.784 (reader 2) by routine knee MR imaging only; with additional oblique coronal imaging, the kappaws increased to 0.809 (reader 1) and 0.843 (reader 2). Interobserver agreements for routine knee MR imaging and additional coronal imaging were considered to be "very good" (kappaw = 0.851, 0.868, respectively). CONCLUSION: Additional use of oblique coronal MR imaging of the knee improves diagnostic accuracy in the grading of ACL injury.     

Dual-detector spiral CT arthrography of the knee: accuracy for detection of meniscal abnormalities and unstable meniscal tears

PURPOSE: To determine the sensitivity and specificity of dual-detector spiral computed tomographic (CT) arthrography of the knee in the detection of meniscal abnormalities and unstable meniscal tears. MATERIALS AND METHODS: The meniscal changes in 50 consecutive patients who underwent dual-detector spiral CT of the knee after intraarticular injection of iodinated contrast material (0.55-mm effective section thickness, 0.75 pitch value, 0.3-mm increment reconstruction, 0.43-mm in-plane resolution, 0.3-mm longitudinal resolution) were determined by two observers and were compared with arthroscopic findings. The sensitivity and specificity of CT arthrography for the detection of meniscal abnormalities and unstable meniscal tears and the kappa statistics for assessing interobserver reproducibility were determined. RESULTS: The sensitivity and specificity for the detection of meniscal abnormalities were 98% and 94%, respectively. The sensitivity and specificity for the detection of unstable meniscal tears were 97% and 90%, respectively. Interobserver agreement was excellent for the detection of meniscal abnormalities (kappa = 0.899) and of unstable meniscal tears (kappa = 0.885). CONCLUSION: Dual-detector spiral CT arthrography of the knee is an accurate and reproducible method for detecting meniscal abnormalities and unstable meniscal tears.     

Can isotropic fast gradient echo imaging be substituted for conventional T1 weighted sequences in shoulder MR arthrography at 3 Tesla?

PURPOSE: To assess the practical utility of isotropic shoulder imaging in patients undergoing MR arthrography. Isotropic shoulder imaging can be performed in less than three minutes with use of fast gradients. MATERIALS AND METHODS: Two experienced musculoskeletal radiologists retrospectively interpreted MR images of the shoulder in 100 consecutive patients undergoing MR arthrography of the shoulder. All patients underwent MRI of the shoulder in oblique coronal, oblique sagittal, and axial planes on a 3.0-Tesla MRI system. All patients had conventional fast spin-echo T1-weighted imaging. All patients also had thin section (0.4 mm) isotropic spoiled gradient echo images performed. A total of 67 of the 100 patients underwent subsequent arthroscopy and results were compared with MR interpretations. RESULTS: There were 41 full-thickness supraspinatus tendon tears, nine partial-thickness supraspinatus tendon tears (seven articular surface and two bursal surface), 21 superior labral, 18 anterior labral, and seven posterior labral tears demonstrated by consensus retrospective reading of the 100 shoulder MR exams. There was no difference in interpretation of the isotropic images as compared to the conventionally acquired images in the oblique coronal, oblique sagittal, and axial planes. Some patients had more than one finding on each exam. A total of 67 patients went on to arthroscopy. There were 41 full-thickness supraspinatus tendon tears, nine partial-thickness supraspinatus tendon tears, 21 superior labral, 18 anterior labral, and seven posterior labral tears demonstrated on arthroscopy. All full- and partial-thickness supraspinatus tendon tears seen at arthroscopy were seen on consensus MR reading. A total of 19 out of the 21 patients with superior labral anterior posterior (SLAP) tears at arthroscopy were seen on consensus MR reading. A total of 16 of the 18 anterior labral tears and six of the seven posterior labral tears seen at arthroscopy were seen on consensus MR reading. Some of the 67 patients had more than one finding on arthroscopy. CONCLUSION: Isotropic imaging of the shoulder is practical in clinical imaging when performed with use of fast gradients on a 3-Tesla system. Isotropic imaging provides the same clinical information as conventional imaging and can be acquired in less than three minutes.     

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OBJECTIVE: We determined whether using two recently described indirect MR imaging signs would improve the sensitivity of diagnosis of lateral meniscal tears. MATERIALS AND METHODS: We identified 121 consecutive patients who had undergone knee MR imaging and knee arthroscopy. Their MR imaging examinations were evaluated for the conventional criteria of a meniscal tear (meniscal distortion or intrameniscal signal contacting the surface) and the two new signs (presence of an abnormal popliteomeniscal fascicle and posterolateral pericapsular edema). These observations were correlated with the arthroscopic findings, which were used as the gold standard. RESULTS: Thirty-two (89%) of the 36 torn lateral menisci had two or more images with distortion or signal contacting the surface. Three torn menisci and eight intact menisci had one image with distortion or surface signal. Only one of 75 menisci without distortion or surface signal was torn. An abnormal superior fascicle was highly associated (p < 0.001) with lateral meniscal tears but was not specific for a tear because three of the 14 menisci with abnormal fascicles were not torn. Posterolateral pericapsular edema was not associated with a lateral meniscal tear (p = 0.06). Using an abnormal fascicle as an additional criterion improved the sensitivity from 89% to 94%, but the difference was not statistically significant. CONCLUSION: We confirmed that an abnormal fascicle is highly associated with a lateral meniscal tear but found that posterolateral pericapsular edema was not associated with lateral meniscal tears. Identifying an abnormal fascicle did not significantly improve the sensitivity of diagnosis of a lateral meniscal tear.     

Correlation between type of discoid lateral menisci and tear pattern

This study analyzed the relationship between type of discoid lateral menisci and tear pattern. There were 108 consecutive cases (103 patients) with discoid lateral meniscus tear treated by arthroscopy. Regarding type of discoid meniscus (Watanabe's classification), 38 cases were "complete" and 70 cases "incomplete." There was no Wrisberg type. Tear patterns were classified into simple horizontal, complicated horizontal, longitudinal, radial, degenerative, and complex tear. The relationship between tear pattern and type of discoid menisci was statistically highly significant. Simple horizontal tear was found only in the complete type of case, and radial, degenerative, and complex tears were found only in the incomplete type of case. In the longitudinal tear, however, we found no correlation between tear pattern and type of discoid meniscus. In addition, the extent of meniscal resection was dependent on the tear pattern. Subtotal or total meniscectomy was performed significantly more frequently in longitudinal and complex tears. In radial and degenerative tears only partial meniscectomy was carried out. Complicated horizontal tears showed no difference in extent of resection. Among the 13 cases of simple horizontal tears partial meniscectomy was performed in 12 cases. These findings about relationship between the type of discoid menisci and tear pattern could be useful in planning operation and deciding extent of resection.