MRI of normal anterior cruciate ligament (ACL) and reconstructed ACL: comparison of when the knee is extended with when the knee is flexed

The purpose of this study was to evaluate, using MRI, the morphology of normal anterior cruciate ligament (ACL) and ACL grafts when the knee was extended compared with when the knee was flexed. Eighteen normal controls and 22 ACL graft patients were studied. Spin-echo (SE) T1-weighted images (TR 330 ms/TE 15 ms, NEX 1) were obtained with a slice thickness of 3 mm. Oblique sagittal images parallel to the ACL were obtained at various flexed angles of the knee joint. In 12 of the 18 normal controls the ACL appeared convex toward the posterior side when the knee was extended and gradually became straight when the knee was flexed. In 15 of the 22 ACL graft patients the grafts appeared straight when the knee was extended and became convex toward the anterior side when the knee was flexed. It is concluded that the morphological changes seen on MR images of ACL grafts from when the knee is extended to when the knee is flexed are different from those in the normal ACL. Received: 11 January 1996; Accepted: 27 December 1996     

Interposition of the Posterior Cruciate Ligament into the Medial Compartment of the Knee Joint on Coronal Magnetic Resonance Imaging

Objective

The purpose of our study was to evaluate the overall prevalence and clinical significance of interposition of the posterior cruciate ligament (PCL) into the medial compartment of the knee joint in coronal magnetic resonance imaging (MRI).

Materials and Methods

We retrospectively reviewed 317 consecutive patients referred for knee MRI at our institution between October 2009 and December 2009. Interposition of the PCL into the medial compartment of the knee joint on proton coronal MRI was evaluated dichotomously (i.e., present or absent). We analyzed the interposition according to its prevalence as well as its relationship with right-left sidedness, gender, age, and disease categories (osteoarthritis, anterior cruciate ligament tear, and medial meniscus tear).

Results

Prevalence of interposition of PCL into the medial compartment of the knee joint was 47.0% (149/317). There was no right (50.0%, 83/166) to left (43.7%, 66/151) or male (50.3%, 87/173) to female (43.1%, 62/144) differences in the prevalence. There was no significant association between the prevalence and age, or the disease categories.

Conclusion

Interposition of the PCL into the medial compartment of the knee joint is observed in almost half of patients on proton coronal MRI of the knee. Its presence is not associated with any particular factors including knee pathology and may be regarded as a normal MR finding.     

Assessment of normal ACL double bundle anatomy in standard viewing planes by magnetic resonance imaging

Anatomical studies show that the native ACL consists of two distinct functional bundles, termed the anteromedial (AM) and posterolateral (PL) bundles. The utility of using routine magnetic resonance imaging (MRI) to distinguish the individual bundles of the ACL has not been evaluated. The purpose of this study was to evaluate the intra- and inter-observer agreement for assessment of the AM and PL bundles using MRI in the axial, coronal, and sagittal viewing planes. We identified a series of patients seen in the senior author’s clinic during a 16-month period. Images were independently evaluated in blinded fashion at two separate time points by a musculoskeletal radiologist and two orthopaedic residents. The AM bundle was detected in most planes of view with high frequency and reliability, while detection of the PL bundle was less frequent and had a lower associated reliability. Our results indicate that it is difficult to reliably detect both the AM and PL bundles using a low-field strength magnet with standard planes of view. It has been demonstrated that the ACL may be imaged effectively in planes that are based on the natural course of the ligament, and it is likely that this will also facilitate visualization of the individual AM and PL bundles. The use of additional oblique planes of view offers a potential approach for improved evaluation of the ACL, even with low field strength magnets. Future work in this area may assist in the pre-operative assessment of isolated AM or PL bundle injuries, facilitating a more anatomic approach to ACL reconstruction.     

The value and limitation of gadopentetate-enhanced magnetic resonance imaging in detecting the condition of anterior cruciate ligament in rheumatoid knee: comparative study with histology

The aim of this study was to elucidate the utility and limitation of gadopentetate (Gd)-enhanced MRI as a method for evaluating the anterior cruciate ligament (ACL) in the rheumatoid arthritis (RA) knee, using both surgical macro findings and histological findings to ascertain the pathological condition of the affected knee. Thirty-six knees of 25 RA patients were studied in this study. Four imaging protocols were employed: protocol A, T1-weighted and T2-weighted sagittal images; protocol B, T1-weighted sagittal image, after infusion of Gd-DTPA (0.2 mmol/kg, i.v.); protocol C, T1-weighted angled coronal image, parallel to the ACL; and protocol D, T1-weighted angled coronal image, parallel to the ACL, after infusion of Gd-DTPA. Sagittal image was determined as previously described. Angle coronal image was newly determined as coronal image parallel to the ACL. Surgical and MRI findings of the ACL were classified into four types: Type I (normal group) indicated that the thickness of the ACL was almost normal, adequate tension was maintained (surgical findings),and the ACL had thick and a more complex appearance with a homogeneous signal intensity and well-defined borders (MRI findings). Type II (degenerated group): the ACL had degenerated and tension was reduced (surgical findings), and the ACL had thin and a more complex appearance with a less homogeneous signal intensity and less well-defined borders. This appearance was more evident on Type II than Type I (MRI findings). Type III (ruptured group): the parenchyma of the ACL remained but lacked continuity (surgical findings), and the ACL appeared as partial lack of low signal intensity (MRI findings). Type IV (absent group): the parenchyma of the ACL was practically absent (surgical findings), and the ACL appeared as complete lack of signal low signal intensity (MRI findings). The concordance rate between surgical and MRI findings was investigated. Moreover, we investigated the extent to which histological changes of the ACL could be discriminated using MRI. In RA knees, the overall concordance rate between surgical and MRI findings was 41.7% under imaging protocol A. The overall rate improved up to 69.4% under imaging protocol B. But the overall rate dropped to 36.1% under imaging protocol C. The overall rate improved up to 83.3% under imaging protocol D. Especially, significant differences between imaging protocols A and B (p<0.05), and imaging protocols C and D (p<0.01), with respect to ACL degenerated group, were recognized. But significant differences between imaging protocols A and C, and imaging protocols Ｂ and D, with respect to ACL degenerated group, were not recognized. The concordance rate between histological and MRI findings was 41.7% in ACL normal group, and 61.5% in ACL degenerated group. The concordance rate between surgical and MRI findings was 100% in ACL normal group, and 78.9% in ACL degenerated group. There was a significant difference in the concordance rates between histological, surgical, and MRI findings in normal group (p<0.05). The results of this study suggested that with Gd-enhanced MRI, the degree of synovial proliferation around the ACL and the degree of degradation of the ACL in the RA knee can be evaluated more accurately than with conventional MRI; however, in RA knees with severe synovial proliferation, it may be difficult to discriminate between the invasive synovium going into the ligament from synovium surrounding the ligament. This may be a limitation of Gd-enhanced MRI at present. In the clinical setting, the present imaging technique does allow the ligament to be evaluated to a certain degree, and may prove useful in the evaluation of temporal changes in the RA knee.     

Magnetic resonance imaging of knee trauma

This article reviews the magnetic resonance (MR) appearance of normal knee anatomy and the role of MRI in the evaluation of knee trauma. Images acquired in the sagittal plane are the most useful. A combination of T₁- and T₂-weighted spin echo pulse sequences is most commonly employed. A meniscal tear is identified by an intrameniscal signal which extends to the joint surface. MR and arthroscopic findings agree in more than 90% of patients. It is important to be familiar with the MRI appearance of normal anatomic variants that may be confused with meniscal tears: the transverse geniculate ligament, the hiatus of the popliteal tendon sheath, and the meniscofemoral ligaments. Tears in the anterior cruciate, posterior cruciate, and collateral ligaments are also depicted.The following article is one in a series of review articles which represent expansions of papers presented at the annual meeting of the International Skeletal Society and were solicited by the editors     

Magnetic resonance imaging findings of extrapelvic endometriosis of the round ligament

A 31-year-old woman presented with a mass in her groin accompanied by intense pain during the menstrual period. A poorly circumscribed, elastic, hard mass was palpable in her right inguinal region. Magnetic resonance imaging showed that the mass had continuity with the inguinal course of the round ligament of the uterus. The mass lesion was well enhanced with high intensity on diffusion-weighted imaging. An operation was performed, and the histological diagnosis was endometriosis of the round ligament. After operation, she was completely relieved of pain. It is important to include endometriosis in the differential diagnosis in women with painful inguinal mass lesions at risk for endometriosis.     

膝关节前交叉韧带MR扫描方式的研究

目的：探讨前交叉韧带MRI最佳的扫描方式,提高前交叉韧带MR图像的显示程度。方法：回顾性分析100例前交叉韧带MRI图像。每住受检者都按两种不同扫描方式进行扫描,第一组：斜矢状面以轴面定位像进行扫描;第二组：斜矢状面在第一组定位方式基础上,再在冠状面上按前交叉韧带走行倾斜角度进行扫描,观察两组前交叉韧带MR图像的显示情况,将所得前交叉韧带图像分为可全程显示、可分段显示、不显示三种,最后将统计出的数据进行分析。结果：第一种扫描方式全程显示70例（70／100）、分段显示25例（25／100）、不显示5例（5／100）;第二种扫描方式全程显示95例（95／100）、分段显示5例（5／100）、不显示0例（0／100）。结论：两种扫描方式前交叉韧带的显示程度差异有显著性意义（P〈0．01）,第二种扫描方式对前交叉韧带的显示情况良好,是一种较为理想的扫描方式,能显著提高前交叉韧带的显示率。     

膝关节前交叉韧带前内侧束和后外侧束的MR成像研究

目的 提高对膝关节前交叉韧带前内侧束和后外侧束的影像认识,并探讨其3.0T MR的理想常规成像显示平面.方法 回顾性分析149例正常膝关节的3.0TMR图像,采用x2分割法分析前交叉韧带、前内侧束和后外侧束双束结构及双束上、中、下各段在MR矢状面、冠状面、横断面各成像平面显示率的差异.结果 前交叉韧带前内侧束和后外侧束双束结构显示率,横断面(115/149,77.2％)与冠状面(103/149,69.1％)比较,×2=2.4606,P＞0.0125;横断面、冠状面分别与矢状面(21/149,14.1％)比较,x2值分别为119.5138、92.8695,P值均＜0.0125.前内侧束和后外侧束双束上段显示率,横断面( 104/149,69.8％)与冠状面(7/149,4.7％)、矢状面(0/149,0)及冠状面与矢状面分别比较,x2值分别为135.0813、159.7526、7.1684,P值均＜0.0125.前内侧束和后外侧束双束中段显示率,横断面(108/149,72.5％)与冠状面(94/149,63.1％)比较,x2=3.0120,P＞0.0125;横断面、冠状面分别与矢状面( 10/149,6.7％)比较,x2值分别为134.7454、104.2173,P值均＜0.0125.前内侧束和后外侧束双束下段显示率,横断面(103/149,69.1％)与冠状面(110/149,73.8％)比较,x2=0.8065,P＞0.0125;横断面、冠状面分别与矢状面(18/149,12.1％)比较,x2值分别为100.5300、115.9132,P值均＜0.0125.前交叉韧带双束各段在MRI各序列上均呈低信号,形态、走行正常.结论 3.0TMR常规扫描平面能够在一定程度上显示前交叉韧带的双束结构,横断面和冠状面是较为理想的显像平面.     

Mucoid degeneration of the anterior cruciate ligament: magnetic resonance imaging findings of an underdiagnosed entity

Although imaging and clinical criteria are already established for the diagnosis of mucoid degeneration of the anterior cruciate ligament (ACL), many radiologists remain unaware of their existence. Once regarded as a rare occurrence, it has been recently suggested that its incidence is in fact very much higher than previously thought, and that it is probably underdiagnosed or misdiagnosed as partial ruptures of the ACL or as cystic ganglia. In this review, the authors revisit the literature concerning this subject and present their personal experience with it, stressing the paramount importance of magnetic resonance imaging and correlation with clinical data for a correct diagnosis.     

Differences in graft orientation using the transtibial and anteromedial portal technique in anterior cruciate ligament reconstruction: a magnetic resonance imaging study

The purpose of this study was to evaluate differences in graft orientation between transtibial (TT) and anteromedial (AM) portal technique using magnetic resonance imaging (MRI) in anterior cruciate ligament (ACL) reconstruction. Fifty-six patients who were undergoing ACL reconstruction underwent MRI of their healthy and reconstructed knee. Thirty patients had ACL reconstruction using the TT (group A), while in the remaining 26 the AM (group B) was used. In the femoral part graft orientation was evaluated in the coronal plane using the femoral graft angle (FGA). The FGA was defined as the angle between the axis of the femoral tunnel and the joint line. In the tibial part graft orientation was evaluated in the sagittal plane using the tibial graft angle (TGA). The TGA was defined as the angle between the axis of the tibial tunnel and a line perpendicular to the long axis of the tibia. The ACL angle of the normal knee in the sagittal view was also calculated. The mean FGA for group A was 72°, while for the group B was 53° and this was statistically significant (P < 0.001). The mean TGA for group A was 64°, while for the group B was 63° (P = 0.256). The mean intact ACL angle for group A was 52°, while for the group B was 51°. The difference between TGA and intact ACL angle was statistically significant (P < 0.001) for both groups. Using the AM portal technique, the ACL graft is placed in a more oblique direction in comparison with the TT technique in the femoral part. However, there are no differences between the two techniques in graft orientation in the tibial part. Normal sagittal obliquity is not restored with both techniques. Paper presented at the 6th Biennial ISAKOS Congress, Florence, ITALY, 2007 and 12th ESSKA 2000 Congress, Innsbruck, Austria 2006.     

MRI多征象分析对前交叉韧带损伤的诊断价值

目的：评价MRI对前交叉韧带（anterior cruciate ligament,ACL）损伤多种征象的诊断价值。方法：回顾分析了128个膝关节的MR图像。全部膝关节均行关节镜检查,其中52个膝关节的ACL损伤,另外76个膝关节的ACL显示完整。在不告知关节镜结果的前提条件下,2名影像科医生共同对ACL损伤的5个直接征象和10个间接征象进行评价,意见不一致时协商解决差异。结果：在评价的5个直接征象中,ACL不连续和ACL走行异常具有相对高的诊断敏感性和特异性;在评价的10个间接征象中,大多数具有相对高的特异性和低的敏感性,其中空髁间窝征、Notch征、外侧半月板后角裸露征、PCL指数、冠状面PCL单层显示等征象特异性较高。结论：ACL损伤的直接征象为诊断的主要依据,以ACL不连续和ACL走行异常具有较高的诊断价值;ACL损伤的间接征象具有辅助诊断意义,其中空髁间窝征、Notch征、外侧半月板后角裸露征、PCL指数、冠状面PCL单层显示等征象最具有诊断价值。     

Natural history of bone bruises after acute knee injury: clinical outcome and histopathological findings

The purpose of this paper is to review the scientific literature on the natural history of bone bruises and the experimental studies regarding the histopathological effects of impaction load on articular cartilage and subchondral bone. Bone bruises with subchondral or osteochondral injuries, or geographic bone bruises seemed to be persistent for years after trauma on MRI. Biopsy samples of the articular cartilage overlying the bone bruise lesions showed degeneration or necrosis of chondrocytes and loss of proteoglycan. Experimental studies using a single impact load revealed chondrocytes death, alteration of the mechanical properties of cartilage explants and/or an increase in the thickness of subchondral bone. These data are indicative of a significant injury to normal articular cartilage homeostasis, and support the suggestion that severe bone bruise is a precursor of early degenerative changes. We recommend delaying return to full weightbearing status when a severe bone bruise is detected to prevent further collapse of subchondral bone and further aggravation of articular cartilage injury.     

Evaluation of the vascular status of autogenous hamstring tendon grafts after anterior cruciate ligament reconstruction in humans using magnetic resonance angiography

The purpose of this study is to evaluate the vascular status of autogenous semitendinosus grafts after anterior cruciate ligament reconstruction in humans using magnetic resonance angiography. Twelve patients (mean age, 24.3 years) who underwent anterior cruciate ligament reconstruction with the 4-strand semitendinosus tendon were studied. All patients underwent contrast-enhanced magnetic resonance angiography and second-look arthroscopy in their reconstructed knees on an average of 15.8 months (range 9–22 months) after surgery. Blood vessels to the graft were visualised and contrast medium enhancement for visualising the femoral tunnel, graft, and tibial tunnel was evaluated. Magnetic resonance angiography showed that a branch of the middle genicular artery extended to the upper side of the graft through the posterior capsule and that branches of the inferior genicular artery ended at the lower side of the graft in all patients. These were consistent with the actual findings of the second-look arthroscopy. We found contrast medium enhancement in the femoral and tibial tunnels in all patients. The effect of enhancement at 9 months after ACL reconstruction was higher than that at 22 months. The graft showed enhancement patterns in the posterior portion of the femoral side and the anterior portion of the tibial side. This study demonstrated that the branches of the middle and inferior genicular arteries provide blood supply to the graft, which may influence the maturation of the graft. The revascularisation of the bone tunnels could play an important role in the healing of the ligament–bone tunnel junction.     

Serial magnetic resonance imaging of the donor site after harvesting the central third of the patellar tendon A prospective study of 37 patients after arthroscopic anterior cruciate ligament reconstruction

The aim of this prospective study was to follow the development of repair tissue in the donor-site area using serial magnetic resonance imaging (MRI) evaluation and to assess whether the MRI findings were correlated with donor-site morbidity. Thirty-seven consecutive patients with unilateral anterior cruciate ligament injuries undergoing elective reconstruction of the ligament were included in the study. They were aged 27 (range 14–50) years. The graft was harvested through two 25-mm vertical incisions with the aim of protecting the infrapatellar nerve and sparing the paratenon. The tendon defect was left open. The patients underwent MRI evaluation at 6 weeks, 6 months and 27 months postoperatively. A final clinical follow-up was made 25 (range 23–29) months postoperatively. MRI demonstrated that the donor-site gap, i.e. the area corresponding to a pathological non-tendinous-like tissue signal, was 9 (range 4–18) mm at 6 weeks, 5 (range 2–14) mm at 6 months and 2 (range 0–5) mm at 27 months. The size of the donor-site gap had significantly decreased at 6 months compared with 6 weeks (P = 0.0001), as well as at 27 months compared with 6 months (P = 0.0001). We conclude that the patellar tendon at the donor site healed gradually, as expressed by a decrease in the area of non-tendinous-like tissue signal on the serial MRI evaluations. Received: 3 March 1998 Accepted: 28 May 1998     

Magnetic resonance imaging of truama patterns in the knee

This review describes how knee trauma results in recognizable patterns of soft tissue and osseous injury. The features of these injuries on magnetic resonance imaging are described, and examples are presented. Recognition of these magnetic resonance patterns of knee trauma will help the radiologist more accurately diagnose the type and extent of knee injuries.     

Mucoid degeneration of the anterior cruciate ligament with erosion of the lateral femoral condyle

We report a case of a mucoid degeneration of the anterior cruciate ligament (ACL) that produced osseous erosion of the medial aspect of the lateral femoral condyle. The MRI findings and differential diagnosis are discussed.     

颈椎病患者后纵韧带的磁共振影像及临床意义

目的：探讨颈椎病后纵韧带的磁共振影像特点及其临床意义。方法：对2000年4月。2002年4月的42例颈椎病的磁共振影像和临床资料进行回顾性分析。结果：磁共振检查提示后纵韧带骨化9例，后纵韧带肥厚17例，颈椎问盘脱出16例。16例行颈椎后路手术，26例行颈椎前路手术切除后纵韧带。平均改善率为61．8％，优11例，占31．4％；良14例，占40％；一般8例，占22．9％；差2例，占5．7％。结论：MRI对后纵韧带骨化、后纵韧带肥厚和颈椎问盘脱出的诊断有重要价值，对手术方案的选择有重要意义。     

前交叉韧带损伤的MRI诊断与关节镜下所见的比较研究

目的：探讨MRI对前交叉韧带(ACL)损伤的诊断准确率极其对临床治疗的指导意义。方法：7l例关节镜手术患者术前行MRI检查，根据MRI诊断分为正常、部分损伤和断裂组，将MRI诊断结果与关节镜下所见进行对比。结果：以关节镜下所见为标准，MRI诊断准确率正常组为87．5％(7／8)，部分损伤组为61．9％(13／21)，断裂组为90．5％(38／42)。本组MRI诊断ACL损伤总诊断准确率为95．8％。ACL与胫骨平台夹角小于450和各序列扫描均未见ACL影像为诊断ACL完全断裂的可靠依据。结论：MRI是诊断ACL损伤的有效无创性检查方法，但部分损伤与完全断裂有时难以鉴别，ACL重建术前应常规行关节镜探查。     

Pictorial review: magnetic resonance imaging of colonic diverticulitis

Magnetic resonance imaging (MRI) is rapidly emerging as a useful imaging modality for the evaluation of the gastrointestinal tract. Increasingly rapid sequences and improving hardware have significantly improved the visualisation of diseases of the colon. MRI has a major advantage over CT in that there is no ionising radiation. In our institution, MRI has increasingly been used as a complimentary imaging modality to CT in the diagnosis and evaluation of diverticulitis and its complications. In this review article, we illustrate the emerging role of MRI in the diagnosis and evaluation of colonic diverticulitis.     

Magnetic resonance imaging findings of vulvar epithelioid sarcoma

We describe here a case of vulvar epithelioid sarcoma. Epithelioid sarcoma is a malignant appendicular skin tumor that is rarely of vulvar origin. Magnetic resonance imaging (MRI) revealed a solid mass with an ulcer-like lesion and multilobulated contour. To our knowledge, this is the first case of vulvar epithelioid sarcoma described in the MRI literature.