Meniscal changes in the elderly: correlation of MR imaging and histologic findings.

In elderly patients, degenerative changes of the meniscus are common and may mimic a tear. The magnetic resonance (MR) image findings of 179 meniscal sections in 20 cadaver knees were correlated with the histologic and gross pathologic findings. The sensitivity of standard T1-weighted spin-echo images and their corresponding meniscal windows in depicting meniscal tears was 80.6%, specificity was 72.4%, and accuracy was 76.7%. These results are not as good as results reported previously. A major difficulty is the occurrence of grade 3 meniscal signal intensity and diffuse intrameniscal signal intensity in torn and intact menisci. MR imaging in elderly patients, however, is still useful in the diagnosis of meniscal abnormalities. Normal low signal intensity depicted within a meniscus at MR imaging and changes in grades 1 and 2 intrameniscal signal intensity are reliable signs of an intact meniscal surface. Grade 3 and diffuse meniscal signal intensities do not allow a specific diagnosis; menisci with these characteristics should be described as degenerated with a high probability of a tear.     

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.     

The "notch" sign: meniscal contour deformities as indicators of tear in MR imaging of the knee

Conventional magnetic resonance (MR) criteria for meniscal tearing emphasize intrameniscal signal and its communication with the articular surface. In this retrospective study, the value of a focal contour deformity of the meniscal articular surface, termed a "notch," as an additional MR sign of meniscal tearing was assessed. One hundred fifty-four menisci were evaluated. Twenty-three of 24 notches correlated with the site of tear at arthroscopy. Seven notches improved the reading confidence from possible to definite tear; in eight notches, the diagnosis of tear would otherwise not have been considered. Five tears occurred without intrameniscal signal, four following recent trauma. The notch sign improved the sensitivity from 79.8 to 87.8%. Notches are useful additional signs of meniscal tearing, increasing the confidence of a reading when occurring near grade 1 or 2 meniscal signal, and are the only MR sign present in some tears.     

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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.     

The high signal intensity meniscus of the knee. Magnetic resonance evaluation and in vivo correlation

This study describes the different appearances of meniscal abnormalities on magnetic resonance (MR) images and correlates macroscopic and histologic findings. Twenty-three of 40 cadaveric menisci with MR signal abnormalities were examined macroscopically; five of the 23 were studied histologically. In addition, MR studies of seven patients (14 menisci) were examined and findings were correlated arthroscopically. Histologic analysis was performed on two of these menisci. The two major findings on MR images were: (1) abnormal, high, centrally located signal intensity within the meniscus and (2) disruption of the peripheral meniscal contour. Macroscopically evident meniscal degeneration correlated well with findings on MR images in all cases. Histologic abnormalities included microcyst formation and separation of collagen bundles. Four menisci with intact outer contour lines on MR images had macroscopically identifiable tears. In addition, two meniscal tears were appreciated only after intra-articular injection of gadolinium-DTPA. We conclude that MR imaging is superior to macroscopic examination as performed by arthroscopy or arthrotomy for the detection of degenerative meniscal lesions. The technique also accurately identifies meniscal tears, a capability that might be enhanced by prior intra-articular injection of MR contrast agents.     

Do asymptomatic marathon runners have an increased prevalence of meniscal abnormalities? An MR study of the knee in 23 volunteers

Excessive repetitive musculoskeletal loads and stresses associated with intense physical activity may lead to deterioration of the menisci of the knee. Therefore, MR imaging was performed on the knees of 23 asymptomatic marathon runners (eight men, 15 women; average age, 40 years; average number of years training, 10; average training distance per week, 41 miles) to determine the prevalence of meniscal signal abnormalities. None of the runners had previous knee injuries or surgery and each of them regularly competes in 26-mile, 50-mile, or 100-mile marathon races. T1-weighted coronal MR images and proton density-weighted and T2-weighted sagittal images were obtained with a 1.5-T MR system and a transmit/receive extremity coil. The medial and lateral menisci were divided into four portions, or horns, and a total of 92 horns were evaluated (i.e., four horns per knee: medial posterior, medial anterior, lateral posterior, and lateral anterior). Two meniscal horns (2%) had grade 3 signal (grade 3 indicates a meniscal tear), 12 (13%) had grade 2 signal, 29 (32%) had grade 1 signal (grades 1 and 2 are indicative of meniscal degeneration), and 49 (53%) had grade 0 signal (grade 0 is normal). Overall, the prevalence of meniscal tears was 9% (two meniscal tears found in 23 runners). This is lower than the prevalence of MR signal abnormalities indicative of meniscal tears reported for asymptomatic, nonrunner athletes (20% of 20 athletes) and for asymptomatic nonathletes (16% of 74 subjects). Fifty-three percent of the meniscal horns of the nonrunner athletes had grade 1 or 2 signal, indicative of meniscal degeneration. Our results indicate that the prevalence of meniscal tears in marathon runners is no higher than the prevalence reported for sedentary persons, and the runners have the same amount of meniscal degeneration as do nonrunner athletes.     

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.     

Silent meniscal abnormalities in athletes: magnetic resonance imaging of asymptomatic competitive gymnasts

BACKGROUND: Magnetic resonance imaging (MRI) produces exceptionally detailed images of the intra-articular structures of the knee. Recognising the range of MRI appearances within a normal population is therefore necessary in order to avoid attributing a greater significance to these than is clinically justified. OBJECTIVE: To compare MRI appearances in asymptomatic gymnasts with those in a less active population in order to identify findings that may be seen in the absence of significant pathology and thereby aid the clinical management of this athletic group. METHODS: MR images were obtained from 24 knees of asymptomatic competitive American collegiate gymnasts aged 18-22. The menisci were evaluated according to established grading criteria, and compared with a group of controls matched for age and sex. RESULTS: Grade 3 intrameniscal signal abnormalities are considered to be highly correlated with meniscal tears. When compared with control group, the experimental group of gymnasts had a significantly different distribution (p<0.001) of grade 3 intrameniscal signal changes, preferentially involving the lateral meniscus. The overall incidence of grade 3 changes (13%) in gymnasts was not, however, significantly different from the incidence in the controls. CONCLUSIONS: A knowledge of these MRI appearances is important when evaluating the lateral menisci within this group of athletes to prevent unnecessary treatment or intervention. This is particularly pertinent when the imaging findings do not closely correlate with the site of symptoms.     

膝关节半月板撕裂的MRI（与手术,关节镜对照研究）

目的：研究半月板内信号接触关节面的特定型式与半月板撕裂的关系。材料和方法：分析了９８例临床怀疑半月板撕裂病人的膝关节ＭＲ资料，并与手术或关节镜检查结果进行对照研究。结果：信号接触关节面的半月板发生撕裂的机率明显高于不接触和可能接触的半月板（Ｐ＜００１）。信号可能接触关节面的半月板与不接触的半月板发生撕裂的机率无显著性差异（Ｐ＞００５）。当一层以上图像显示半月板内信号接触关节面时，发生半月板撕裂的机率在９０％以上；而只有一层图像显示半月板内信号接触关节面时，发生半月板撕裂的机率在内侧半月板为５０％，外侧半月板为３３％。半月板撕裂最好发的部位是半月板的后角。结论：当半月板内信号与关节面无接触或可能接触时，发生半月板撕裂的可能性均较小；当只有一层图像显示半月板内信号接触关节面时，诊断为半月板可能撕裂较妥，当一层以上图像显示信号接触关节面时，诊断为月板撕裂较可靠     

MR imaging of the knee in the sagittal projection: comparison of three-dimensional gradient-echo and spin-echo sequences

Fifty patients with suspected internal derangement of the knee had arthroscopic examinations after MR imaging with both a standard T1-weighted spin-echo (SE) sequence and a three-dimensional (3-D) gradient-echo sequence. This series permitted correlative evaluation of 100 menisci and 50 anterior cruciate ligaments. Meniscal tears were diagnosed when intrameniscal signal communicated with the meniscal surface. Criteria for diagnosing anterior cruciate ligament disruption included absence or discontinuity of the ligament, ligamentous laxity, and hyperflexion of the posterior cruciate ligament. Arthroscopic surgery confirmed the presence of 39 meniscal tears and 11 anterior cruciate ligament tears in this population. The sensitivity and specificity of the SE sequence for the diagnosis of meniscal tears were 77% and 98%, respectively. The 3-D gradient-echo sequence had a sensitivity of 87% and a specificity of 88%. For disruption of the ligament, the SE technique had a sensitivity of 82% and a specificity of 95% and the 3-D technique had a sensitivity of 64% and a specificity of 100%. Although these differences in sensitivity and specificity are not statistically significant at the p less than .05 level, probably because of the small sample size, the results show the relative strengths and weaknesses of the two imaging sequences. These data suggest that because of the complementary results of the two MR techniques, both the SE and the 3-D gradient-echo sequences have a role in the diagnosis of knee injuries.     

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.     

Meniscal injuries: detection using MR imaging

Both retrospective and blinded analyses of thin-section, high-resolution magnetic resonance (MR) images of the knee joint, produced using a solenoid surface coil, indicate that MR imaging is an effective technique for evaluating meniscal injuries. Images of 49 patients were evaluated, and the results were correlated with those of subsequent arthroscopy. A grading scale was developed to rate the index of suspicion of a meniscal tear based on the MR images. Overall, approximately 80% of menisci rated grade 4 (definite tear) or 3 (probable tear) were found to have corresponding tears at arthroscopy. In many other patients with a grade 4 or 3 meniscus in whom a corresponding tear was not found arthroscopically, meniscal tears at other sites or other abnormalities were correctly diagnosed using MR. A majority of the false-positive MR images involved the posterior horns of the menisci, the sites of most false-negative arthroscopic diagnoses. The predictive value of a negative MR image was almost 100%. Even in patients with moderate-to-large effusions, the menisci were accurately evaluated. The results imply that MR imaging is useful in the preoperative evaluation of suspected meniscal tears.     

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.     

MR diagnosis of meniscal tears of the knee: value of axial three-dimensional Fourier transformation GRASS images.

Axial MR images of 40 knees in 37 patients with clinically suspected meniscal tears were obtained by using a three-dimensional (3-D) Fourier transform, gradient-refocused acquisition in the steady state (GRASS) pulse sequence. All knees also were examined in both coronal and sagittal planes with a two-dimensional (2-D) Fourier transform, spin-echo pulse sequence for T1-weighted images and a multiplanar GRASS pulse sequence for T2*-weighted images (conventional 2-D pulse sequences). Arthroscopic confirmation was available in all cases and was used as the gold standard. In these 40 knees, 32 of 33 meniscal tears and 45 of 47 normal menisci were correctly identified with axial 3-D imaging, yielding a sensitivity of 97% and specificity of 96%. Conversely, the sensitivity was 82% and the specificity was 100% for the 2-D technique in the diagnosis of meniscal tears. A combination of both techniques yielded 100% sensitivity, 100% specificity, and 100% accuracy in the evaluation of the menisci. Seven discrepancies between the findings of the two techniques were found in the evaluation of 33 arthroscopically proved torn menisci; six of the seven represented false-negative 2-D images and one was a false-negative axial 3-D image. Of 47 normal menisci, only two false-positives occurred with axial 3-D imaging and none with 2-D imaging. Despite the lack of a statistically significant difference, these preliminary findings suggest that the sensitivity in the diagnosis of meniscal tears can be improved by adding thin-sliced axial images with the 3-D GRASS pulse sequence to conventional 2-D imaging.     

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.     

Peripheral meniscal tears: MR findings after conservative treatment or arthroscopic repair

Follow-up knee magnetic resonance (MR) examinations were performed on 17 patients (18 menisci) with arthroscopically proved tears of the outer third of the meniscus who were treated either conservatively (six patients) or with surgical repair (11 patients). All patients satisfied accepted clinical orthopedic criteria for meniscal healing. MR examinations obtained 3-27 months after injury revealed persistent signal intensity (grade 3), unchanged from that seen on the preoperative study, in all 15 patients in whom both pre- and postoperative studies were obtained and in three of four menisci that were proved to be healed at second-look arthroscopy. It appears that grade 3 signal from both conservatively treated and repaired menisci may persist long after the tear has become asymptomatic and has presumably healed. The presence of such signal should not be interpreted as necessarily indicating meniscal retear in these patients. Persistent signal intensity at the site of previous injuries may account for some reported cases of disagreement between MR and arthroscopic findings.     

半月板可疑撕裂的MRI与关节镜对照研究

研究半月板可疑撕裂的出现机率及其临床意义。材料和方法：回顾性分析了１２６个膝关节的ＭＲ扫描资料，当二位放射科医生均不能肯定半月板内的高信号是否延伸至半月板表面时，诊断为半月板可颖撕裂，并与关节镜检查结果进行对照。结果：１２６例中有２２例诊断为半月板可疑撕裂，占１７．５％。１２例位于内侧半月板的后角，４例位于外侧半月板的前角，６例位于外侧半月板的后角。２２例中１８例作了关节镜检查，只有２例发现有撕裂     

Abnormal superior popliteomeniscal fascicle and posterior pericapsular edema: indirect MR imaging signs of a lateral meniscal tear

OBJECTIVE. Because MR diagnosis of lateral meniscal tears can be difficult, indirect signs may be useful when a tear is suspected. We studied whether an abnormality of the superior popliteomeniscal fascicle or pericapsular edema was associated with lateral meniscal tears and thus may be an indirect MR imaging sign of a lateral meniscal tear. MATERIALS AND METHODS. We identified 59 consecutive patients who underwent both knee MR imaging examinations and knee arthroscopy. Thirty patients had lateral meniscal tears, and 29 had intact lateral menisci. We reviewed paired sagittal proton density- and T2-weighted MR images from these 59 patients for abnormal superior popliteomeniscal fascicles and edema surrounding the posterolateral capsule. RESULTS. The superior popliteomeniscal fascicles were abnormal in nine of the 30 patients with torn lateral menisci but were normal in all 29 patients with intact menisci (p = 0.001). Abnormal fascicles were apparent only when the lateral meniscal tear involved the posterior horn. Posterior pericapsular edema was seen in 10 patients with a torn posterior horn and in one patient with an anterior horn tear of the lateral meniscus, but in only two patients with intact menisci (p = 0.006). CONCLUSION. The presence of superior popliteomeniscal fascicle abnormalities and of posterior pericapsular edema is significantly associated with a tear of the lateral meniscus, most commonly in the posterior horn. Noting the presence of these findings may help improve the accuracy of MR diagnosis of lateral meniscal tears.     

The role of T2-weighted fast-spin-echo imaging in the diagnosis of meniscal tears

The objective of this study was to compare the accuracy of T2-weighted fast-spin-echo (FSE) and intermediate-weighted spin-echo (SE) MR imaging in the detection of meniscal tears. Seventy-six patients (152 menisci) who had arthroscopic surgery after MR imaging of the knee were studied. MR imaging included intermediate-weighted SE and T2-weighted FSE sequences. The use of intermediate-weighted conventional SE images, T2-weighted FSE images, and a combination of both sequences were evaluated in the detection of meniscal tears. T2-weighted FSE imaging was slightly less accurate than intermediate-weighted SE imaging in the diagnosis of meniscal tears. Interpretation of the menisci using both intermediate-weighted SE and T2-weighted FSE imaging did not improve the accuracy over intermediate-weighted imaging evaluated in isolation.     

Diagnostic efficacy in knee MRI comparing conventional technique and multiplanar reconstruction with one-millimeter FSE PDW images

Background: Magnetic resonance (MR) imaging has proved to be an excellent tool in diagnosing injuries of the cruciate ligaments and menisci. However, multiple planes and sometimes optimal oblique or double-oblique scan planes are needed due to the variability in the positioning of important structures, which means there is a lower throughput and longer scanning time.

Purpose: To compare the performance of a 1-mm-thickness fast spin-echo (FSE) proton-density-weighted (PDW) MR imaging technique with multiplanar reconstruction (MPR) in diagnosing tears of the menisci and cruciate ligaments with that of conventional MR imaging.

Material and Methods: Twenty-five consecutive patients underwent preoperative conventional and 1-mm-thickness FSE PDW MR imaging with subsequent knee arthroscopic surgery. Two musculoskeletal radiologists evaluated the status of the cruciate ligaments and menisci using two sets of MR images (method A: conventional images including seven sequences, taking 26 min; method B: 1-mm-thickness FSE PDW images with MPR, taking 7 min 20 s). The diagnostic efficacies of both methods for tears of the cruciate ligament and menisci were calculated and compared.

Results: Arthroscopic surgery revealed 10 anterior cruciate ligament (ACL) tears, one posterior cruciate ligament (PCL) tear, and 26 meniscal tears. The diagnostic values of both methods were 100% for a cruciate ligament tear. The diagnostic values (sensitivity, specificity, accuracy, positive predictive value, and negative predictive value) for meniscal tears were 90%, 100%, 96%, 100%, and 94% for method A, and 95%, 100%, 98%, 100%, and 97% for method B, respectively. There were no significant differences in the diagnostic values between methods A and B.

Conclusion: 1-mm-slice-thickness FSE PDW imaging with MPR showed comparable performance in diagnosing tears of the cruciate ligaments and menisci to conventional sequences but the scan time was much shorter. Therefore, this technique (method B) might improve the throughput of a 3T MR imaging system.