Postoperative meniscus: assessment at dual-detector row spiral CT arthrography of the knee

PURPOSE: To assess the effectiveness of dual-detector row spiral computed tomographic (CT) arthrography of the knee in the evaluation of the postoperative meniscus for recurrent or residual meniscal tear. MATERIALS AND METHODS: Spiral CT arthrography was performed in 20 patients who presented with pain after partial meniscectomy. Findings at the initial reading of the images and at two retrospective independent readings were compared with those at second-look arthroscopy performed in all patients. At initial interpretation, conventional criteria for meniscal tear were used, including partial- or full-thickness tear of any size and meniscal separation. At retrospective interpretation, criteria for meniscal tear included large partial- and full-thickness tear and meniscal separation but not small partial-thickness tear. Sensitivity and specificity for the detection of tear of the postoperative menisci were calculated for initial and retrospective readings. RESULTS: At initial interpretation, the sensitivity and specificity for the detection of tear of the postoperative menisci were 100% and 78%, respectively. At retrospective interpretation, the sensitivity and specificity for the detection of tear of the postoperative menisci were 79% and 89% at reading 1 and 93% and 89% at reading 2, respectively. CONCLUSION: Spiral CT arthrography is valuable for the assessment of postoperative menisci, but the application of conventional definitions of meniscal tear to arthrographic findings in postoperative menisci can lead to overestimation of the clinical importance of meniscal lesions.     

CT Arthrography and Virtual Arthroscopy in the Diagnosis of the Anterior Cruciate Ligament and Meniscal Abnormalities of the Knee Joint

Objective

To determine the diagnostic accuracy of CT arthrography and virtual arthroscopy in the diagnosis of anterior cruciate ligament and meniscus pathology.

Materials and Methods

Thirty-eight consecutive patients who underwent CT arthrography and arthroscopy of the knee were included in this study. The ages of the patients ranged from 19 to 52 years and all of the patients were male. Sagittal, coronal, transverse and oblique coronal multiplanar reconstruction images were reformatted from CT arthrography. Virtual arthroscopy was performed from 6 standard views using a volume rendering technique. Three radiologists analyzed the MPR images and two orthopedic surgeons analyzed the virtual arthroscopic images.

Results

The sensitivity and specificity of CT arthrography for the diagnosis of anterior cruciate ligament abnormalities were 87.5%-100% and 93.3-96.7%, respectively, and those for meniscus abnormalities were 91.7%-100% and 98.1%, respectively. The sensitivity and specificity of virtual arthroscopy for the diagnosis of anterior cruciate ligament abnormalities were 87.5% and 83.3-90%, respectively, and those for meniscus abnormalities were 83.3%-87.5% and 96.1-98.1%, respectively.

Conclusion

CT arthrography and virtual arthroscopy showed good diagnostic accuracy for anterior cruciate ligament and meniscal abnormalities.     

Computed tomography of the knee with reference to meniscal tears. A prospective blind investigation

Computed tomography (CT) with a high resolution CT scanner and--on a special occasion--double contrast arthrography of the knee with reference to meniscal tears were performed in 50 patients. Operation or arthroscopy was performed in 28 patients and 15 were found to have meniscal tears. A correct diagnosis of the tears was achieved at CT in 13 of these patients. Three false positive and two false negative CT findings were recorded, resulting in a 91 per cent accuracy for CT, a diagnostic specificity of 84 per cent, and a sensitivity of 95 per cent. The diagnostic value of CT thus compared with that of double contrast arthrography. This should indicate that CT may be used as an alternative non-invasive diagnostic procedure in the diagnosis of meniscal tears of the knee joint.     

Meniscus tears of the knee: prospective evaluation with CT

A total of 209 patients underwent prospective axial computed tomography (CT) examinations of the knee to evaluate the ability of this technique to identify and characterize knee menisci in patients believed to have meniscus tears. Of the 359 knees examined, 105 subsequently underwent arthrography, arthroscopy, or arthrography and arthroscopic surgery. In this group, the sensitivity of CT was 88.5%, specificity was 95.5%, and accuracy was 91.5%. Although axial CT is a sensitive and effective method for the detection and characterization of tears involving the medial and lateral menisci, purely horizontal or nondisplaced peripheral tears may be difficult to demonstrate.     

Diagnosis of recurrent meniscal tears: prospective evaluation of conventional MR imaging, indirect MR arthrography, and direct MR arthrography

PURPOSE: To prospectively investigate the accuracy of conventional magnetic resonance (MR) imaging, direct MR arthrography, and indirect MR arthrography in assessment of possible recurrent or residual meniscal tears. MATERIALS AND METHODS: Three hundred sixty-four patients who had previously undergone meniscal preservation surgery were prospectively examined with conventional MR imaging, indirect MR arthrography, and direct MR arthrography. Ninety-four patients (104 postoperative menisci) underwent subsequent second-look arthroscopic surgery. Each case was evaluated for (a) surfacing intrameniscal intermediate- or T1-weighted signal intensity, (b) surfacing intrameniscal T2-weighted signal intensity, (c) morphologic changes beyond those expected postoperatively, (d) joint effusion on conventional MR or indirect MR arthrographic studies, and (e) overall presence or absence of recurrent meniscal tear. RESULTS: Seventy-one arthroscopically proved recurrent meniscal tears were found. In the diagnosis of recurrent meniscal tears, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 86%, 67%, 83%, 71%, and 80%, respectively, for conventional MR imaging; 83%, 78%, 90%, 64%, and 81%, respectively, for indirect MR arthrography; and 90%, 78%, 90%, 78%, and 85%, respectively, for direct MR arthrography. No significant difference in the diagnostic accuracy of one method relative to another was observed (P >.54). Surfacing intrameniscal T2-weighted signal intensity was the most specific sign, with the highest positive predictive value of a recurrent tear. CONCLUSION: Although a small incremental increase in accuracy is associated with the use of direct MR arthrography over conventional MR imaging and indirect MR arthrography, no significant difference in diagnostic accuracy among the three techniques was demonstrated for detection of recurrent or residual meniscal tear.     

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.     

Tears of the anterior cruciate ligament and menisci of the knee: MR imaging evaluation

In 242 of 3,000 patients who underwent magnetic resonance (MR) imaging of the knee between September 1986 and August 1987, original MR imaging reports were compared with subsequent arthroscopic reports to determine the value of MR imaging in the evaluation of suspected meniscal and complete tears of the anterior cruciate ligament. The overall accuracy for the menisci was 93% (sensitivity, 95%; specificity, 91%) with a false-negative rate of 4.8%. For the anterior cruciate ligament the overall accuracy was 95%. T2-weighted sequences were associated with greater sensitivity, specificity, and accuracy than were T1 sequences; the false-negative rate was 0% in the T2-weighted group. MR imaging of the knee is an extremely accurate means for noninvasive assessment of the integrity of the menisci and anterior cruciate ligament, and the accuracy exceeds that usually reported for arthrography.     

间接法MRI膝关节造影对半月板撕裂的评价

目的　评价间接法MRI膝关节造影对半月板撕裂的诊断价值。方法　回顾性分析 75例常规MRI膝关节扫描和 6 4例间接法MRI膝关节造影病例资料 ,以膝关节镜检查为诊断金标准 ,对比分析常规MRI和间接法MRI膝关节造影对半月板撕裂的诊断。结果　间接法MRI膝关节造影对内侧半月板撕裂的诊断敏感性、特异性、准确性、阳性预测值和阴性预测值分别为 72 %,10 0 %,89.1%,10 0 %和 84.8%;对外侧半月板撕裂分别为 83.8%,90 .9%,87.5 %,89.6 %和 85 .7%。与常规MRI比较 ,间接法MRI膝关节造影对内外侧半月板撕裂的诊断能力都没有统计学差异。结论　尽管间接法MRI膝关节造影对内外侧半月板撕裂诊断价值很高 ,但与常规MRI比较没有统计学差异。     

Evaluation of recurring meniscal tears with gadolinium-enhanced magnetic resonance imaging: a randomized, prospective study

BACKGROUND: Magnetic resonance imaging has been shown to be of questionable accuracy in detecting recurrent meniscal tears after previous resection or repair. PURPOSE: To compare the accuracy of nonenhanced magnetic resonance imaging with that of intraarticular contrast-enhanced direct magnetic resonance arthrography and intravenous contrast-enhanced indirect magnetic resonance arthrography for detection of recurrent meniscal tears. STUDY DESIGN: Prospective cohort study. METHODS: Forty-one patients who had previous meniscal tears treated by resection or repair but who were experiencing recurrent knee symptoms were prospectively randomized into one of three groups: conventional magnetic resonance imaging, indirect arthrography, and direct arthrography. The interpretations of two musculoskeletal radiologists were compared with the findings of an arthroscopic procedure performed 2 to 14 weeks later. RESULTS: Conventional imaging had a sensitivity of 57.9%, specificity of 80%, and overall accuracy of 62.5%. Intravenous contrast improved the sensitivity to 90.9%, specificity to 100%, and overall accuracy to 93.8%; intraarticular contrast had a sensitivity of 91.7%, specificity of 100%, and an overall accuracy of 92.9%. CONCLUSIONS: We demonstrated an increased accuracy of intravenous or intraarticular contrast-enhanced magnetic resonance arthrography in detecting recurrent meniscal tears. Both contrast routes demonstrated similar accuracy, a finding not previously reported.     

Value of modern sonography in the assessment of meniscal lesions

The aim of this prospective study was to assess the accuracy of modern ultrasonography in diagnostic imaging of meniscal tears. One hundred and sixty menisci were evaluated in 80 patients (42 females, 38 males, mean age=36.2 years, range=16-70 years). Inclusion criteria for the study were twofold: clinical suspicion of meniscal injury and clinical indication for arthroscopy. Knee examination was performed with the Voluson 730 Expert ultrasound system (General Electric). After sonographic examination, all patients underwent arthroscopic procedures within 1-4 days. The final diagnosis of meniscal tears was taken from surgical reports. The overall sensitivity, specificity, positive predictive value and negative predictive value of sonographic examination in the assessment of meniscal tears amounted to 85.4%, 85.7%, 67.3% and 94.4%, respectively. The statistical parameters were not statistically different in medial and lateral menisci. Age, sex, body mass index (BMI), weight, physical activity, mechanism on injury, and time lapse from injury did not have a statistically significant impact on the usefulness of ultrasonography. The highest sensitivity (>90%) was obtained in medial menisci and in patients with a BMI>25. The highest specificity (>90%) was obtained in lateral menisci, in patients after twisting injuries, in sports injuries, and in recent injuries (time lapse from the injury <1 month). The positive predictive value (PPV) of sonographic examination was higher than 90% only in recent injuries (<1 month), however, the negative predictive value of ultrasound is high, being less than 90% in males with lesions of lateral menisci and in sequelae of sports injuries.     

Imaging the post-operative meniscus

Considerable developments have occurred in meniscal surgery, and consequently in the imaging of post-operative menisci, over the last 15 years. A drive to preserve meniscal physiologic function for as long as possible, in order to delay osteoarthrosis, has resulted in limited partial meniscectomies, meniscal repairs and meniscal transplants. Each of these techniques affects the imaging appearance of the meniscus, reducing the accuracy of conventional MRI in predicting recurrent tears. The specificity of conventional MRI can be improved by employing at least two T2-weighted sequences, but this still leaves a shortfall in sensitivity. In an attempt to increase the diagnostic accuracy of cross-sectional imaging, MR arthrography (MRA) and CT arthrography (CTA), have been applied to the post-operative meniscus. Sensitivities and specificities for these two techniques approach 90% in predicting recurrent meniscal tears. In the setting of clinical symptoms and gross meniscal deficiency, meniscal allografts are being transplanted with increasing frequency. In these transplants meniscal degeneration, fragmentation and separation are common findings, but the role of imaging in the management of these patients has not yet been well defined. This review explores the imaging techniques available for the evaluation of the post-operative meniscus, their strengths and weaknesses, and the reasons that they may find a place in a rational strategy for imaging of the symptomatic post-operative knee.     

Meniscal lesions of the knee joint: CT diagnosis

Computed tomography (CT) resulted in a diagnostic accuracy of 89.2% and 96.1% for medial and lateral meniscal lesions, respectively, in 109 patients who underwent surgery after a direct CT study of the knee joint for a clinically suspected meniscal lesion. The meniscal lesions were the only pathologic condition found in 59 patients, while in 35 patients they were associated with various lesions of the cruciate ligaments (31 cases) and collateral ligaments (15 cases) and with cystic bursitis (6 cases). In the remaining 15 patients, the menisci were normal, but in eight of these cases, lesions of other knee joint structures were present. If meniscal lesions are clinically suspected, direct CT study of the knee joint may be considered the elective radiologic diagnostic method, rather than the more invasive arthrography. It may also be helpful in selecting patients for diagnostic and therapeutic arthroscopy.     

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。     

Meniscal tears: MR and arthrographic findings after arthroscopic repair

Magnetic resonance (MR) imaging was performed on 29 previously repaired menisci and one conservatively treated meniscus (total, 30 menisci). Intermediate- and T1-weighted MR sequences revealed persistent signal intensity extending to an articular surface (grade 3 signal intensity) in 27 of the 30 menisci. On T2-weighted images, seven of the 30 menisci were found to contain unequivocally higher signal intensity, defined by a full-thickness defect (grade 3 signal intensity involving two articular surfaces) increasing in signal intensity to a level equivalent to that of joint fluid. The MR imaging and arthrographic appearances of 23 of the 30 menisci were compared. Arthrographic examination revealed partial or complete healing in 13 menisci and tears in 10. The presence of grade 3 signal intensity on intermediate- and T1-weighted MR images did not reliably predict a tear seen at arthrography. Unequivocally higher signal intensity on T2-weighted images is a useful sign in the prediction of a persistent meniscal tear (sensitivity, 60%; specificity, 92%; P less than .02). Since presence of grade 3 signal intensity on intermediate- and T1-weighted images does not reliably predict a tear and unequivocal T2 increase in intensity has a sensitivity of only 60%, arthrography should be considered for assessment of the symptomatic, previously repaired meniscus.     

Evaluation of a chest phantom for CT nodule densitometry

The characteristics of a chest phantom used for CT nodule densitometry were determined by use of a GE CT 9800 scanner (General Electric, Milwaukee, WI). The supplied reference rods were scanned in different positions within the lung fields of the phantom and with varied chest wall thicknesses. The liver/spleen inserts were added. The CT attenuation values of different-size rods and their mineral content were also tested. The size of the standard rod is the major determinant of its CT number, which varied from 1 to 83 H. The standard rods contained no measurable calcium or other mineral. Position-dependent variability in CT numbers was relatively small with the GE CT 9800 scanner. The simulated chest wall additions and liver/spleen inserts produced only small increases in CT density. We conclude that the GE CT 9800 scanner, as an example of one of the newer CT scanners, shows improved operating characteristics for pulmonary nodule densitometry. Nodule densitometry should be further evaluated with simplified phantoms.     

FasT-Fix半月板缝合的临床疗效与MRI造影评估愈合研究

目的:了解关节镜下使用FasT-Fix系统进行半月板缝合的临床疗效与MRI造影下的愈合情况。方法:2006年4月至2007年7月,17例患者、18侧损伤半月板在我所应用Fast-Fix系统进行了关节镜下全内的半月板缝合,所有患者同时进行了交叉韧带重建,于术后平均11个月进行临床随访,依照Barrett标准评价半月板缝合的临床愈合情况,并对随访患者进行IKDC、Lysholm和Tegner评分。所有18侧半月板应用MRI造影评价半月板愈合情况。结果:18侧缝合的半月板有17侧得到了临床愈合,临床愈合率为94.4%。平均IKDC评分由术前的46.4分提高至术后的75.2分,平均Lysholm评分由术前的44.8分提高至术后的80.6分,平均Tegner评分由术前的2.5分提高至术后的5.4分。MRI造影显示18侧半月板中13侧为完全愈合,2侧为部分层厚不愈合,3侧为全层厚不愈合,总愈合率为83.3%,完全愈合率为72.2%。结论:应用Fast-Fix系统进行半月板缝合具有很好的临床效果,MRI造影显示有较高的愈合率。     

Anterior cruciate ligament tears and associated meniscal lesions: assessment at dual-detector spiral CT arthrography

PURPOSE: To assess dual-detector spiral computed tomographic (CT) arthrography of the knee in the evaluation of anterior cruciate ligament (ACL) tears and associated meniscal lesions. MATERIALS AND METHODS: ACL and meniscal abnormalities in 125 consecutive patients who underwent dual-detector spiral CT arthrography of the knee were evaluated on the basis of both initial interpretations and retrospective review of CT images and were compared with arthroscopic findings. The sensitivity and specificity of CT arthrography for the detection of ACL tears and meniscal lesions in knees with abnormal ACLs were determined. RESULTS: The sensitivities and specificities for the detection of ACL tears were 90% and 96%, respectively, at initial interpretation and 95% and 99%, respectively, at retrospective interpretation. The sensitivities and specificities for the detection of meniscal tears in knees with abnormal ACLs were 92% and 88%, respectively, at initial interpretation and 96% and 94%, respectively, at retrospective interpretation. CONCLUSION: Dual-detector spiral CT arthrography of the knee is an accurate method for detecting ACL tears and associated meniscal lesions.     

低场强磁共振成像诊断半月板撕裂的准确性研究

目的验证低场强磁共振成像(MRI)诊断半月板撕裂的准确性．方法171例患者经低场强MRI检查，显示半月板损伤的情况，后经过关节镜诊断，分别记录检查结果，并进行比较。结果低场强MRI对内外侧半月板撕裂诊断准确度分别为95．9l％、95．9l％，敏感度分别为95．60％、96．47％，特异度分别为96．25％、95．35％。结论低场强MRI对半月板撕裂的诊断有很高的准确性，同时有良好的性价比。     

Comparison of echo planar imaging, gradient echo and fast spin echo MR scans of knee menisci.

In order to reduce the acquisition time, we compared a three-dimensional multi-shot echo-planar imaging (EPI) sequence with fat-suppression with two widely used sequences, the fat-suppressed gradient echo (GRE) and the proton-density weighted turbo spin-echo (FSE) in imaging the menisci of the knee. Sixty patients with various indications were studied prospectively with MRI. The menisci were imaged in the sagittal plane with all three sequences using a 1T MR scanner with 15mT/m gradients. The signal-to-noise ratio (SNR) of bone (b), cartilage (c), and meniscus (m) as well as contrast-to-noise ratio (CNR) and relative contrast (ReCon) between menisci and cartilage and between bone and cartilage were measured. A qualitative analysis was performed on grading of meniscal pathology (0-IV). The imaging accuracy of meniscal pathology was assessed compared to arthroscopy in 13 patients. The EPI provided the highest SNR in cartilage and meniscus (p<0.001), the highest CNR and the highest ReCon between bone and cartilage (p< or =0.001). MR grading of meniscal abnormalities showed overestimation compared to GRE and FSE. The EPI sequence could not be included in the routine protocol in imaging the menisci since the overestimation of meniscal abnormalities could lead to unnecessary arthroscopy.     

Double-contrast arthrography in meniscal pathology. Remarks on 1000 cases

The authors performed a statistical study on a series of 1000 patients examined with double-contrast fluoroscopically-guided knee arthrography. Arthrographic diagnoses were compared with the arthrotomic (500 patients), arthroscopic (350 patients) or clinical diagnoses of 150 patients with a follow-up of 6 months. In this series of patients with a history of "recurrent meniscal injury", arthrographic diagnoses were confirmed in a high percentage of cases, with 96.9% accuracy, 96.7% sensitivity for tears, and 98.6% specificity. On the basis of these results the authors suggest double-contrast arthrography as an examination of considerable value in the diagnosis of meniscal lesions, while in their opinion arthroscopy should be limited to questionable cases, to complex lesions with involvement of multiple articular structure and to the alterations clearly treatable by arthroscopy.