【Abstract】Objective To explore the value of MRI in assisting percutaneous transluminal vertebral kyphoplasty in the treatment of osteoporotic compression fractures of the thoracolumbar spine. Methods We retrospectively analyzed the patients who were hospitalized in our hospital for PKP from October 2007 to October 2008, compared the preoperative MRI results with X-rays, used the MRI results to develop preoperative plans, and used visual analog scoring to evaluate the results. The results of 24 cases were successfully completed, and no cement leakage occurred.The VAS scores of the patients before and after surgery were statistically significant (p<0.01). Conclusion MRI-assisted preoperative planning for PKP is necessary to help identify the diseased vertebrae. Li Shuwen, Department of Cervical Spine Surgery, The Second Affiliated Hospital of Inner Mongolia Medical University, Inner Mongolia, China 【Keywords】 osteoporosis; thoracolumbar compression fracture; percutaneous puncture vertebral kyphoplasty; magnetic resonance imaging Application value of MRI in the preoper ative plan PKP Li shuwen,Yin Heping , Wu Yimin. bai ming, liu cong, cao zhenhua (Department of minimally invasive spine surgery of the Second Affiliated Hospital of Inner Mongolia Medical College. Huhhot, 010030, China) [Author's address] Department of minimally invasive spine surgery of the Second Affiliated Hospital of Inner Mongolia Medical College, Huhhot, China. Mongolia Medical College, Huhhot, 010030, China 【Abstract】Objective To discuss the auxiliary value of Magnetic resonance imaging (MRI) in percutaneous kyphoplasty (PKP) for the treatment of thoracolumbar osteoporotic vertebral compression fractures (OVCF). 24 patients with OVCF underwent PKP in our hospital from October 2007 to October 2008 were retrospectively investigated. All the operations were planed according to the MRI result before the treatment. All the operations were planned according to the MRI result before the operation. The MRI was compared with the X-ray and the clinical effection was evaluated by the Visual Analogue Scale (VAS). The MRI was compared with the X-ray and the clinical effection was evaluated by the Visual Analogue Scale (VAS). The MRI was compared with the X-ray and the clinical effection was evaluated by the Visual Analogue Scale (VAS). 24 cases were successfully completed, no bone cement leakage occurs. VAS result showed statistically significant improvement after the operation (p < 0.01). Conclusion MRI is very necessary for the operation plan of PKP for the thoracolumbar osteoporotic vertebral compression fractures, and which can help MRI is very necessary for the operation plan of PKP for the thoracolumbar osteoporotic vertebral compression fractures, and which can help distinguish which vertebra was injured before the operation. 【Key words】osteoporosis; vertebral compression fractures (VCF); percutaneous The use of percutaneous kyphoplasty (PKP) in the treatment of osteoporotic vertebral compression fractures (OVCF) in the thoracolumbar spine has been recognized in recent years, and can help distinguish which vertebra was injured before the operation. compression fractures (OVCF)) in the treatment of low back pain caused by osteoporotic vertebral compression fractures (OVCF) [1, 2], and has been widely used in clinical practice. We used MRI-assisted PKP preoperative planning for 24 patients with thoracolumbar compression fractures and achieved good results, which are reported as follows. 1 DATA AND METHODS 1.1 GENERAL DATA From October 2007 to October 2008, 24 patients with osteoporotic thoracolumbar compression fracture underwent PKP in our hospital, aged 49-78 years old at the time of surgery, 10 males and 14 females; 17 cases of single vertebral body fracture, 7 cases of two vertebral body fracture, with a total of 31 vertebral bodies, T11 5, T12 9, L1 12, L2 2. L3 1, L4 2. All patients underwent bone density examination and were diagnosed with osteoporosis. All patients had pressure and percussion pain at the corresponding lesion site, and the pain was obvious when they turned over, making it difficult for them to sit up or stand up, and they could only lie down in bed. All patients were treated with strict bed rest, non-steroidal anti-inflammatory drugs and calcitonin for 1 to 3 weeks without symptomatic relief, and there was no contraindication for surgery. 1.2 Preoperative imaging examination In addition to X-ray examination, all patients underwent routine CT examination to observe the posterior wall of the vertebral body and the pedicle root for damage, and MRI examination to evaluate the scope and nature of the lesion and assist in the preoperative planning.MRI examination was performed using the 0.5T magnetic resonance imaging system of Siemens Germany, and the examination time ranged from 1 to 32 days, with an average of 8.5 days.The SE spin-echo sequences were used to make sagittal and axial T1-weighted (T1-weighted) measurements, and the T1-weighted (T1-weighted) measurements were performed in the sagittal and axial positions. SE spin echo sequence, made sagittal and axial T1-weighted (TR/TE440/10.7ms), T2-weighted (TR/TE2400/103ms) scans, layer thickness of 1mm, layer spacing of 4mm, matrix 320×256, and sagittal STIR images. 1.3 Surgical methods The prone position was taken, and the operating table was adjusted so that the lumbar region was in the hyperextension position to facilitate postural repositioning. After connecting the cardiac monitor to monitor the vital signs, C-arm fluoroscopy was performed to determine the position of the target vertebrae. If the spinous processes of the target vertebrae were located at the midpoints of the two vertebral arches, it meant that the vertebrae were not rotated, and the upper and lower endplates of the affected vertebrae were shown as a line of shadow in the orthopedic position, and then the puncture point was marked on the surface of the body, i.e., the orthopedic image was located at the outer and upper edges of the shadow of the pedicle. In this group, cement was injected through the left pedicle root puncture, disinfected and toweled, anesthetized with 1% lidocaine local infiltration to the periosteum layer by layer, and an incision of about 3 mm was made, and a percutaneous perforation balloon dilatation vertebral kyphoplasty set of surgical instruments (home-made) was used, and unilateral percutaneous percutaneous percutaneous percutaneous percutaneous puncture was made into the vertebral body under fluoroscopic vision. The C-arm should be adjusted to observe the position on the front and side images during the puncture process. When the needle is inserted into the vertebral body via the pedicle in the lateral position to reach the posterior edge of the vertebral body, the orthopedic position should be located at the inner edge of the pedicle shadow, and if it exceeds the range of the pedicle shadow, the tip of the needle should be alerted to penetrate out of the lateral wall of the pedicle. If the tip of the needle exceeds the posterior margin of the vertebral body in the lateral position, the puncture can be stopped and the core removed, i.e., the establishment of the working channel can be completed at one time. The bone drill is used to drill into the vertebral body along the working channel and reaches about 2-3 mm from the anterior wall of the vertebral body. The bone drill is withdrawn and a guide needle is used to investigate the vertebral body, and the tip of the needle should ideally be positioned at or above the vertebral body midline in the orthostatic view. After confirming the position, a manometer injection device is attached and a balloon is inserted. The ideal position of the balloon under lateral fluoroscopy is in the anterior 3/4 of the vertebral body. The balloon is injected with contrast medium (iohexol, a nonionic, water-soluble contrast medium) under continuous fluoroscopic monitoring and the balloon is slowly expanded. The balloon injector pressure is observed and recorded, and the insert is removed when it is pressurized to 50 PSI (1 PSI = 6.89 Pa) to facilitate expansion of the balloon within the vertebral body. The maximum expansion pressure should be less than 250 PSI and no more than 300 PSI. When the vertebral body height is satisfactorily restored or the balloon reaches the upper and lower endplates of the vertebral body, the pressurization is stopped, the contrast medium is withdrawn, and the balloon is withdrawn. The PMMA (polymethylmethacrylate) bone cement is prepared and pushed into the vertebral body under low pressure under continuous fluoroscopy during the doughnut stage. The injection was stopped when the cement was satisfactorily filled. After satisfactory distribution of PMMA under fluoroscopic observation in the front and side positions, the injection catheter was rotated several times to separate it from the bone cement before the cement solidified, and then the injection device was withdrawn and local pressure was applied for 5 minutes and then covered with a sterile dressing. The patient was allowed to move down to the ground under the protection of the support after 1-2 days after the operation. 1.4 Postoperative efficacy assessment methods The visual analogue scale (VAS) of pain intensity was performed before and 3 days after the operation to assess whether the patients' pain was relieved. 1.5 Statistical methods SPSS 11.5 software was applied, and the t-test was used for paired measurement data, with a test level of α = 0.05. 2 Results In this group of 24 patients, 32 vertebrae were observed on imaging and 31 vertebrae were operated on, and one vertebrae was shown to have wedge-shaped changes on preoperative X-rays, and the T1 and T2 images of MRI showed isosinusoidal signals, suggesting that it was an old fracture that had not been subjected to PKP. two vertebrae were shown to have normal X-rays, and two vertebrae showed high signals on MRI T2 images. MRI T2 image showed high signal and corresponding spinous processes were positive for pressure and percussion pain, suggesting a missed diagnosis on X-ray. The amount of cement injected into each vertebra was 2-4 ml, and there was no cement leakage or other complications.The VAS score was 8.12±1.23 before surgery and 2.10±0.75 at 3 days after surgery, which was a significant difference (P<0.05). 3 Discussion 3.1 Indications and contraindications for PKP OVCF is the main indication for PKP, especially for those patients with severe chest and back pain and loss of mobility despite analgesic treatment, and in order to prevent complications caused by prolonged bed rest, PVP is an important treatment. It is generally believed that there is no absolute contraindication to PKP, and relative contraindications include: (1) vertebral body compression of more than 75%; (2) vertebral body burst fracture or fracture involving the posterior wall of the vertebral body; (3) coagulation dysfunction; and (4) severe cardiovascular disease or poor physical condition that cannot tolerate the surgery [3]. For elderly patients with poor physical condition, the use of cardiac monitors to monitor blood pressure and other vital indicators during the operation can improve the safety of the operation.The mechanism of pain relief by PKP is still unclear, and it may be that the analgesic effect is achieved by direct fixation of vertebral fracture and microfracture by bone cement or by destroying the structure of sensitive nerve endings through the cytotoxicity of PMMA monomers in the cement.The heat energy released by the bone cement during polymerization leading to the destruction of painful nerves may also play a role in analgesic effect.The heat energy released by the bone cement in polymerization may also lead to the destruction of painful nerves. The heat energy released during the polymerization of bone cement leads to the destruction of painful nerves may also be one of the reasons for analgesia [4]. 3.2 Application value of MRI in OVCF In 1977, magnetic resonance imaging equipment began to be used in the clinic, which is favored by doctors of various specialties because of its excellent soft tissue contrast, non-radiation damage and non-invasive, and its ability to cut cross-sectional, coronal and sagittal tomographic images according to the different needs and complete the examination without turning the body, and other advantages. The application of magnetic resonance imaging (MRI) in orthopedics mainly focuses on limb bone and iliac muscle tumors, infections, osteoarthritic diseases, periarticular ligament injuries, and spinal cord injuries and diseases, which has gradually replaced some traditional imaging methods such as myelography, arthrogram, and even angiography [5].MRI can scan and take the cross-sectional images of the spine in the axial, coronal, and sagittal positions in an arbitrary direction, and it is able to observe the injury situation as a whole, such as vertebral body compression. Injuries, such as vertebral compression fractures or burst fractures, are characterized by changes in the shape and alignment of the vertebral body. Vertebral fractures show different MRI signal intensities in fresh and old fractures due to bone marrow edema, exudation, intravertebral hemorrhage, vertebral bone compression, and fracture repair [6]. Fresh vertebral body fractures show high signal in T2-weighted image and equal or low signal in T1-weighted image, and it is believed that these changes are mainly related to the prolongation of T1 and T2 caused by bone marrow edema and exudation after vertebral body fracture, and old fractures show low signal or equal signal in both T1 and T2 weighted images, and it is believed that this is mainly related to vertebral bone compression and fracture repair. After acute injury, there is often no change in the shape of the vertebral body and the T2 weighted image is high signal, suggesting that the vertebral body is traumatized to bone marrow edema, which cannot be observed on X-ray or CT, and it is an important guidance for treatment. In this group of cases, one case was diagnosed as T12 vertebral compression fracture by X-ray on admission, and MRI found that the T2-weighted images of L2 and L4 vertebrae showed high signal, but the signal of T12 vertebrae was normal. Further examination of the body confirmed the diagnosis of recognizing T12 as an old fracture, and the reason for this admission was L2 and L4 vertebral body fracture, which avoided missed diagnosis and misdiagnosis (Figures 1, 2, 3, and 4). For multi-segment or jump-segment injuries, MRI examination is less likely to miss the diagnosis because it can show more vertebrae at the same time, compared with X-ray or CT scanning, which is prone to the error of not seeing the whole mountain. In this group of cases, another case was found to have wedge-shaped changes of T12 and L1 vertebrae in the preoperative X-ray examination, but the MRI examination found that the signal of T12 vertebrae was normal, while the T2-weighted image of L1 and 3 vertebrae showed high signals. Through further inquiring about the history of the disease and detailed examination, it was confirmed that T12 vertebrae was an old fracture, which was not the reason of the present symptom, whereas L1 and 3 vertebrae was a fresh fracture, so that the diagnosis and misdiagnosis were avoided. Misdiagnosis and misdiagnosis were avoided. Therefore, for patients with suspected osteoporotic vertebral compression fractures who are proposed to undergo PKP, preoperative MRI examination is of great significance in determining the injured vertebrae and formulating the surgical plan. The above summarizes the positive significance of MRI in vertebral compression fracture, but at the same time, it also has its limitations: 1) the patient's body can not have paramagnetic substances during the magnetic vibration scanning, such as steel internal fixation devices, external fixation braces or traction devices, iron dentures, and the body of the leftover iron or steel foreign objects, such as shrapnel, etc., and in addition, patients with a cardiac pacemaker in the body are also considered to be a contraindication to MRI scanning because the magnetic field may affect the pacemaker and jeopardize the patient's health. In addition, patients with cardiac pacemakers are also considered contraindicated for MRI scanning because the magnetic field may affect the pacemaker and jeopardize the patient's life. Especially OVCF patients are mostly elderly patients, this point needs to be emphasized. ②Magnetic vibration examination in the display of bone ilium, especially the bone cortex, regardless of T1 or T2 weighted image are manifested as low signal or no signal, so it is often difficult to find some subtle fractures, but fat suppression technology can often find some subtle fractures. ③Magnetic vibration scanning takes a long time, which may be fatal in some patients with injuries, because they may be combined with other serious injuries and need continuous treatment, some even need emergency surgery, for these patients can only wait until later when the condition is stabilized and then perform this examination, and at this time the X-ray examination is obviously fast, convenient and can be carried out at the bedside or in the operating room. In addition, the sound emitted during the magnetic resonance examination may also cause fear and adverse effects to some patients after serious trauma. The high price is also a frequently mentioned problem, especially for patients who need to undergo multiple magnetic resonance examinations. References: Figure 1 X-ray showed T12 vertebral compression fracture Figure 2 MRI compression fat image showed L2 and 4 vertebral body high signal, suggesting fresh fracture; T12 vertebral body wedge-shaped change, but no signal change, suggesting old fracture Figures 3 and 4 According to the results of the MRI, preoperative surgical plan was formulated, and percutaneous puncture of the L2 and 4 vertebral body and vertebral body posterior kyphoplasty were performed, and the T12 was left untreated, and the pain disappeared after the operation 1. Ellen H. Balloon kyphoplasty: continuing evidence of efficacy in treating vertebral collapse and fracture [J].J Bone Joint Surg, 2007, 13( 6) 61- 63. 2. De Negri P, Tirri T, Paternoster G, et al. Treatment of painful osteoporotic or traumatic vertebral compression fractures by percutaneous vertebral augmentation procedures: a nonrandomized comparison between vertebroplasty and kyphoplasty[J].Clin J Pain, 2007, 23( 5) : 425- 430. 3. Zheng Jinfeng,Bai Long,Chen Xinlai,et al. Clinical application of percutaneous vertebroplasty in osteoporotic vertebral compression fractures. Chinese Journal of Bone and Joint Injuries,2008,23(8):672-674. 4. Gaitanis IN,Hadjipavlou AG,Katonis PG,et al. Balloon kyphoplasty for the treatment of pathological vertebral compressive fractures.Eur Spine J,2005,14(3):250-252. 5. Wang L,Yang H,Liu WJ,et al.Clinical value of MRI for comprehensive assessment of spinal injuries. Journal of the Third Military Medical University,2009,31(15):1495-1497. 6. Shen Y,Ren H,Zhang YZ,et al. The role of MRI in the evaluation of target vertebrae for percutaneous kyphoplasty. 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