骨软骨损伤：我该如何判断是否有软骨及相关疾病？（软骨损伤后的影像学检查都有哪些？）你需要核磁共振检查

骨软骨损伤：我该如何判断我是否患有软骨及相关疾病？（软骨损伤后的影像学检查都有哪些？）你需要高分辨核磁共振MRI检查

How do I know if I have a Cartilage Problem? (Imaging of Cartilage Injuries)

陶可（北京大学人民医院骨关节科）

图1. 膝关节股骨髁软骨损伤（cartilage damage），主要表现为不同程度的软骨剥脱、丢失。

图2. 膝关节不同类型的软骨损伤（cartilage damage），主要包括：①软骨下骨板的缺血坏死（avascular necrosis），进而导致软骨自下而上的营养缺失，最终发生软骨剥脱脱离；②剥脱性骨软骨炎（osteochondritis dissecans）；③自发性膝关节软骨坏死（spontaneous osteonecrosis of the knee）；④软骨损伤（chondral lesion）；⑤骨软骨损伤（osteochondral lesion）。

Fig. 3. 23-year-old man with a moderate osteochondral defect on the patellar cartilage seen on axial proton density-weighted MRI (a). T1 before (b) and after intravenous contrast administration (c) show a significant decrease of T1 relaxation times in the cartilage lesion area of the medial facet of the patella. There is a focal small but deep lesion and a larger superficial lesion medially which correspond to regions of lower glycosaminoglycan (GAG) content. Precontrast T1 map (a) does not show significant changes, underscoring the importance of postcontrast T1 mapping (c) for GAG evaluation.

图3. 轴向质子密度加权MRI显示的23岁男性，髌骨软骨中度骨软骨缺损（a）。（b）静脉注射造影剂前和静脉注射造影剂后（c）的T1显示髌骨内侧小面积软骨损伤区域的T1弛豫时间显着减少。内侧有一个小而深的局灶性病变和一个较大的浅表病变，对应于糖胺聚糖(GAG)含量较低的区域。造影前T1图(a)没有显示出显着变化，强调了造影后T1映射(c)对于GAG评估的重要性。

Fig. 4. 62-year-old woman with advanced OA in the medial femorotibial compartment. Sagittal proton density-weighted MRI (a) shows marked thinning of cartilage at the weight-bearing central medial femur adjacent to the medial meniscus (large white arrows). Note the large intrachondral osteophyte of the anterior part of the weight-bearing medial femur (small white arrows). Diffuse cartilage damage is also shown at the anterior medial femur (arrowhead). The tibial cartilage appears morphologically normal. The corresponding dGEMRIC image (b) shows a decrease in the dGEMRIC index particularly in the weight bearing areas at the central and posterior tibia (large white arrows) as well as in the superficial zones of the central medial femoral cartilage (small white arrows) representing low GAG concentration.

图4. 62岁女性，股骨内侧间室晚期OA。矢状质子密度加权MRI（a）显示与内侧半月板相邻的负重中央内侧股骨处的软骨明显变薄（大的白色箭头）。注意负重内侧股骨前部的大软骨内生骨赘（白色小箭头）。股骨前内侧（箭头）也显示弥漫性软骨损伤。胫骨软骨形态正常。相应的dGEMRIC图像(b)显示dGEMRIC指数下降，特别是在胫骨中央和后部的负重区域（大的白色箭头）以及股骨中央内侧软骨的浅表区域（小白色箭头），代表低GAG含量。

Fig. 5. Cartilage loss in a patient with baseline meniscal tears in the right knee. ( A ) Coronal DESS MRI at baseline shows normal cartilage at the medial tibiofemoral joint. ( B ) Sagittal intermediate- weighted fat-suppressed MRI at baseline shows a horizontal tear of the posterior horn of the medial meniscus ( small arrows ) with small subchondral femoral bone marrow lesion ( large arrow ). ( C ) Coronal DESS MRI at two-year follow-up shows dramatic cartilage loss at both the weight- bearing medial femur ( small arrows ) and the tibia ( large arrow ), which is confirmed on ( D ), the sagittal intermediate- weighted fat-suppressed MRI. In addition, there are extensive tibial and femoral subchondral bone marrow lesions ( large arrows ) and new joint effusion ( asterisk ). Also, a slight increase in the size of the anterior femoral and tibial osteophytes is observed (small arrows)

图5. 伴有软骨损伤的右膝半月板撕裂患者。(A)冠状DESS MRI显示内侧胫股关节处的软骨正常。(B)矢状位中等加权脂肪抑制MRI显示内侧半月板后角水平撕裂（小箭头）和小的软骨下股骨骨髓病变（大箭头）。(C)两年随访时的冠状位DESS MRI显示，负重的股骨内侧（小箭头）和胫骨（大箭头）均出现明显的软骨损伤，这在(D)矢状加权脂肪抑制核磁共振中得到证实。此外，还有广泛的胫骨和股骨软骨下骨髓病变（大箭头）和新的关节积液（星号）。此外，观察到股骨前部和胫骨骨赘的大小略有增加（小箭头）

The first thing to explain, especially for patients, is why imaging of the knee is required. When patients arrive with a cartilage problem, often in the knee joint (although sometimes in the ankle or hip), the first step is clinical evaluation. However, imaging is also required, particularly in patients with a possible cartilage problem.

If an X-ray is taken, it only reveals whether or not there is osteoarthritis or, after trauma, whether or not there is a fracture. Younger patients in particular can have problems in their knee that are not shown on X-ray, and magnetic resonance imaging (MRI) is therefore required.

Intended audience

This information is aimed at patients who have been identified as needing imaging for cartilage disorders. It is designed to offer an overview of what the procedures entail, as well as briefly discuss the advantages, disadvantages and expectations you should have when undergoing such procedures.

首先要解释的是，尤其是对患者来说，为什么需要对膝关节进行拍片（影像学）检查。当患者出现软骨问题时，通常是膝关节（尽管有时是踝关节或髋关节），第一步是临床评估。然而，也需要成像，特别是在可能有软骨问题的患者中。

如果拍X线片，它只能显示是否有骨关节炎，或者在外伤后，是否有骨折。特别是较年轻的患者，他们的膝关节可能会出现X线未显示的问题（CT检查可理解成断面X线片检查，对于骨关节软组织成像显示有限），因此需要进行磁共振成像(MRI)。

目标受众（阅读者）

此信息针对已被确定为需要对软骨疾病进行影像学检查的患者。它旨在概述这些影像学检查所需的内容，并简要讨论您在进行此类影像学检查时应具备的优点、缺点和期望。

什么是核磁共振？

MRI机器使用磁场和无线电波来形成体内各种结构的图像。需要进行MRI以查看关节中可能存在的软骨问题，更重要的是，MRI必须是好的（高清的）。为此，需要1.5特斯拉，甚至更好的是3T特斯拉MRI。

“特斯拉”Tesla是MRI磁场强度的量度。现代MR系统通常具有1.5或3.0特斯拉的场强。基本上，磁体的场强越高，MRI的质量就越好。此外，对于高质量的MRI，需要专用的关节线圈。线圈是关节周围的一个小笼子，可提高MRI的质量。例如，在膝关节中，有一种特殊的线圈，称为“专用多通道膝关节线圈”，有8个或16个通道。这些通道进一步提高了MRI的质量，因为可以获得更多信号，因此可以更详细地对软骨层进行成像。

线圈越好，扫描仪越好，MRI图像的质量就越好。如果你的图像分辨率高、质量好、对比度好、信噪比好，就可以看到这个相对微小的软骨层有没有病变。

此外，执行MRI的医生应该意识到您可能有软骨问题，以便他们可以使用高分辨率和良好的MRI程序来正确显示软骨。否则，图像可能会显示问题，但无法确定软骨病变的大小、病变的数量以及半月板、前后交叉韧带和下方骨骼的状态。

了解骨骼状况非常重要，因为患者可能有孤立的软骨损伤或软骨缺损，或者可能有骨骼和软骨（“骨软骨”）缺陷，包括下面的骨骼。这对于选择正确的治疗方式非常重要。

此外，软骨缺损的大小至关重要。对于非常小的缺陷，可以使用微骨折治疗。

但如果缺损较大，且周围软骨质量不佳，则可能需要进行软骨移植，如ACI、MACI或骨软骨移植。事先知道这一点很有帮助，因为患者可以签署一份特殊的术前文件，允许外科医生进行软骨活检，这对于这些程序是必要的。未经患者事先许可，不能进行第二次手术的软骨活检，因为它被认为是一种治疗形式。

因此，MRI不仅允许外科医生选择最合适的程序，还可以选择正确的术前文件供患者签署。这也很重要，因为患者的术后护理可能完全不同，康复计划不同或更长。

这就是为什么患者在手术前进行核磁共振检查很重要，尤其是对软骨敏感的核磁共振检查，这样医生才能看到软骨发生了什么情况、缺损的大小和缺损的数量。

其他成像技术能否提供与MRI相同的信息？

如上所述，X线片显示关节的状态，以及是否存在骨关节炎或骨折。换句话说，X线片只是可视化骨骼结构和异常。因此，软骨缺损无法真正可视化。

超声波可视化肌肉或肌腱损伤。如果软骨在穿透超声波的深度内，则可以部分显示软骨。然而，这种能力是有限的，因为高分辨率超声具有组织穿透率低的缺点。

计算机断层扫描(CT)对软骨也不敏感。此外，与CT相关的辐射也存在问题。可以进行 CT联合关节内造影剂，称为关节CT。然而，这仍然存在辐射问题，以及与关节内（关节内）注射造影剂相关的感染风险。仅当患者由于严重的幽闭恐惧症或存在起搏器或类似的植入设备而无法进入MRI机器时，才使用此技术。

然而，大多数软骨损伤患者更年轻，通常可以进入MRI机器。

MRI有什么缺点吗？

MRI没有真正的缺点，尤其是在不需要造影剂的情况下。唯一的风险是MRI的经典禁忌症，如心脏起搏器、心脏直视手术或开颅手术，以及有源电子设备，如输液泵等。有大型金属植入物的患者，尤其是铁磁体（即被磁铁吸引），也不允许进行核磁共振检查。

核磁共振机器里有一些噪音，但给病人戴了护耳器。如果患者非常幽闭恐惧症，机器也可能令人不快。

常见问题(FAQ)

保险公司会支付核磁共振的费用吗？

MRI不是很贵，但也不是特别便宜。如果您的医生认为您的膝关节、髋关节或踝关节的软骨有问题并且您需要进行核磁共振检查，则保险公司必须支付费用*。

然后，患者通常会在MRI扫描后询问保险公司是否会支付软骨修复程序的费用。这是非常昂贵的。然而，它旨在或多或少地治愈关节，或者推迟正在进行的骨关节炎或防止它发展。如果医生提出这样的治疗，保险公司必须支付费用。

*这取决于您居住的国家和相关的医疗保健系统。

我需要做核磁共振吗？

患者通常希望进行核磁共振检查，因此经常会问这个问题。如果怀疑软骨缺损，答案将是“是”。

What is MRI?

MRI machines use magnetic fields and radio waves to form images of a wide range of structures in the body. An MRI is required to see possible cartilage problems in the joint and, more importantly, the MRI has to be a good one. For that, either a 1.5 Tesla or, even better, a 3 Tesla MRI is needed.

‘Tesla’ is a measure of the strength of the MRI’s magnet field. Modern MR systems usually have field strength of 1.5 or 3.0 Tesla. Basically, the higher the field strength of the magnet, the better the quality of the MRI. Additionally, for a high-quality MRI, a dedicated joint coil is needed. The coil is a small cage around the joint that improves the quality of the MRI. In the knee joint, for example, there are special coils called ‘dedicated multi-channel knee coils’, which have 8 or 16 channels. These channels further improve the quality of the MRI, as more signals can be gained and, therefore, the cartilage layer can be imaged in greater detail.

The better the coil, and the better the scanner, the better the quality of the MRI images. If you have images with high resolution and good quality, good contrast and a good signal-to-noise ratio, it will be possible to see if there are any lesions in this relatively tiny cartilage layer.

Furthermore, the physicians performing the MRI should be aware that you might have a cartilage problem, so that they can use a high resolution and a good MRI protocol to properly visualise the cartilage. Otherwise, the images may show a problem, but it will not be possible to determine the size of the cartilage lesion, the number of lesions, and the status of the meniscus, the cruciate ligaments, and the underlying bone.

It is very important to have an idea of the condition of the bones, as the patient may have isolated cartilage injuries or cartilage defects, or may have bone and cartilage (‘osteochondral’) defects, which include the underlying bone. This is very important for choosing the right kind of therapy.

In addition, the size of the cartilage defect is crucial. For very small defects, microfracture therapy can be used.

However, if there is a bigger defect, and the surrounding cartilage is not good quality, cartilage transplantation, such as ACI, MACI, or osteochondral transplantation, may be required. It is helpful to know that beforehand, as the patient can sign a special preoperative document that gives the surgeon permission to perform a cartilage biopsy, which is necessary for these procedures. Cartilage biopsy for a second surgery cannot be performed without prior patient permission, as it is considered a form of therapy.

MRI therefore not only allows the surgeon to choose the most appropriate procedure but also select the correct preoperative documents for the patient to sign. It is also important because the postoperative care of the patient could be completely different, with a different or longer rehabilitation programme.

This is why it is important that patients have an MRI before their procedure, particularly one that is cartilage-sensitive, so that the doctor can see what is happening with the cartilage, the size of the defect and the number of defects.

Can other imaging techniques give the same information as MRI?

An X-ray, as discussed above, shows the status of the joint, and whether there is osteoarthritis or a fracture. In other words, X-ray simply visualises bony structures and abnormalities. Therefore, cartilage defects cannot really be visualised.

Ultrasound visualises muscle or tendon injuries. Cartilage can be partially visualised if it is within the depth of the penetrating ultrasound waves. This ability is limited, however, as high resolution ultrasound has the disadvantage of low tissue penetration.

Computed tomography (CT) is also not sensitive for cartilage. In addition, the radiation associated with CT presents a problem. CT combined with intra-articular contrast agent, known as arthroCT, can be performed. However, this still has the problem of the radiation, coupled with the infectious risk associated with an intra-articular (within the joint) injection of contrast agent. This technique is only be used if the patient cannot go into an MRI machine due to severe claustrophobia or the presence of a pacemaker or similar implanted device.

The majority of cartilage injury patients, however, are younger and can usually go into an MRI machine.

Are there any disadvantages to MRI?

There are no real disadvantages to MRI, especially if a contrast agent is not needed. The only risks are the classical contraindications for MRI, such as cardiac pacemakers, open heart surgery or open cranial surgery, and active electronic devices such as infusion pumps, etc. Patients with large metal implants, particularly if ferromagnetic (i.e., attracted to magnets), are also not allowed to have an MRI.

There is some noise in the MRI machine, but patients are given ear defenders. The machine can also be unpleasant if patient is very claustrophobic.

Frequently Asked Questions (FAQs)

Will the insurance company pay for the MRI?

MRI is not very expensive, but it is not particularly cheap either. If your doctor believes that there is a problem in the cartilage of your knee, hip or ankle joint and you need an MRI, the insurance company has to pay for it*.

Patients then typically ask whether the insurance company will pay for the cartilage repair procedure, following the MRI scan. This is very expensive. However, it is intended to more or less heal the joint, and either postpone ongoing osteoarthritis or prevent it from developing. If a physician indicates such a treatment, the insurance company has to pay for it.

*This is dependent on the country in which you live and the associated healthcare system.

Will I get an MRI?

Patients usually want to have an MRI, and so often ask this question. If a cartilage defect is suspected, the answer will be ‘yes’.

Further reading

· Griffin JW, Miller MD. MRI of the knee with arthroscopic correlation. Clin Sports Med. 2013;32:507-523.

· Trattnig S, Domayer S, Welsch GW, Mosher T, Eckstein F. MR imaging of cartilage and its repair in the knee–a review. Eur Radiol. 2009;19:1582-1594.

· Welsch GH, Mamisch TC, Hughes T, Domayer S, Marlovits S, Trattnig S. Advanced morphological and biochemical magnetic resonance imaging of cartilage repair procedures in the knee joint at 3 Tesla. Semin Musculoskelet Radiol. 2008;12:196-211.

· Trattnig S, Winalski CS, Marlovits S, Jurvelin JS, Welsch GH, Potter HG. Magnetic Resonance Imaging of Cartilage Repair: A Review. Cartilage. 2011;2:5-26.

Keywords

cartilage repair, computed tomography, imaging, Magnetic resonance imaging, MRI, ultrasound, X-ray

关键词

软骨修复，计算机断层扫描，成像，磁共振成像，MRI，超声波，X线