The role of magnetic resonance imaging in the diagnosis of postoperative spondylodiscitis

BACKGROUND: Spondylodiscitis, discitis associated with vertebral osteomyelitis may follow disc-removal surgery. A targeted successful treatment of spinal infections requires clinical and laboratory data that are completed by the contribution of imaging procedures. Neuroimaging provides precise information on correct topography, localization, propagation, and differential diagnosis of spinal infectious lesions. The aim of this study was to present magnetic resonance imaging (MRI) findings in patients with postoperative spondylodiscitis. METHODS: MRI was performed in 6 patients aged 29-50, with clinically suspected postoperative spondylodiscitis. Initial examination was performed 3-8 weeks after surgery and 3, 6, or 12 months after the treatment by antibiotics. Patients underwent MRI on a IT imaging unit (Siemens, Magnetom-Impact), including sagittal T1W and T2W images and axial T1W images before and after the administration of gadolinium contrast medium. RESULTS: MRI findings included: significantly decreased signal intensity with the loss of distinction between vertebral body and intervertebral disc space on T1W, increased signal intensity in the adjacent vertebral body and end-plates on T2W, contrast enhancement of vertebral body and disc space and paravertebral soft tissue changes. Follow-up examinations performed 3, 6, or 12 months after the treatment showed less abnormal signal intensities on both T1- and T2-weighted images. CONCLUSION: Postoperative spondylodiscitis is a rare but severe complication of lumbar disc surgery. Since conventional imaging techniques are not reliable for detecting spondylodiscitis in its early stages, MRI is of great significance in the diagnosis of postoperative spondylodiscitis.     

Radiologic diagnosis of spondylodiscitis: role of magnetic resonance

PURPOSE: To report the Magnetic Resonance Imaging (MRI) features of acute and chronic spontaneous spondylodiscitis as well as any typical patterns which can be useful for the differential diagnosis between pyogenic and tuberculous forms. MATERIAL AND METHODS: Eleven patients affected with spontaneous spondylodiscitis were selected for the study; they were 7 men and 4 women ranging in age 33-87 years (mean: 64). We excluded the patients with iatrogenic spondylodiscitis. MR images were acquired with a superconductive magnet at 1.5, with the following sequences: sagittal PD and T2-weighted TSE, sagittal T1-weighted SE, axial PD and T2-weighted TSE for the lumbar spine, axial T2-weighted GRE for the cervical and dorsal spine and axial and sagittal T1-weighted SE after contrast agent (gadolinium DTPA) injection. MR images were reviewed by three experienced radiologists and morphological and signal intensity changes of vertebral body and disk were recorded on a standard form. In 9 patients it was possible to compare MR to CT findings. RESULTS: At the time of our observation all patients reported pain at the spine level, associated with fever and weight loss in 50% of cases and with increased values of the inflammatory markers. Three patients had infectious diseases in other organs and 2 were diabetics. Biopsy was performed in two cases only and demonstrated Staphylococcus aureus in one and Mycobacterium tuberculosis in the other patient. MRI allowed the correct diagnosis to be made in all cases, demonstrating the pathological involvement of the paravertebral structures and into the spinal canal earlier and more accurately than CT. A common finding in pyogenic and tuberculous spondylodiscitis was the low signal of the subcortical bone marrow on T1-weighted sagittal images, which enhanced after Gd-DTPA administration and became intermediate or high on T2-weighted images. Moreover, the steady high signal intensity of the disk on T2-weighted images and its contrast enhancement on T1-weighted images is typical for an acute inflammatory process. CONCLUSIONS: Based on our personal experience and literature data, we believe MRI to be the most sensitive technique for the diagnosis of spondylodiscitis in the acute phase, whereas it is comparable to CT in the chronic stage of the disease. At present MRI does not allow to differentiate pyogenic from tuberculous forms.     

同反相位减影图对肾上腺肿瘤的诊断价值

目的 探讨同反相位减影图对肾上腺肿瘤的诊断价值.方法 回顾性分析40例肾上腺肿瘤患者同反相位减影图,对肾上腺肿瘤的同、反相位信号强度指数(SII)、肾上腺肿瘤-脾脏信号比(ASR)、肾上腺抑制指数(ASI)、脂肪含量(FF)进行测量.采用Mann-Whitney U进行统计学检验,并通过ROC曲线计算各种指标的最佳阈值、敏感性、特异性及曲线下面积(AUC).结果 肾上腺腺瘤及非腺瘤的SII、ASR、ASI、FF差异有统计学意义(P＜0.05).IP/OP数据集(SII值)与同、反相位图像减影图(FF值)肾上腺肿瘤的AUC分别为0.802,0.838.结论 同反相位减影图有利于肾上腺含脂性肿瘤的诊断.     

The effect of intravenous gadolinium on the magnetic resonance appearance of cerebrospinal fluid

The authors determined whether a sufficient amount of intravenously administered gadolinium enters the cerebrospinal fluid (CSF) to visibly shorten the T1 relaxation time. Transfer of intravenously administered contrast media into the CSF has been previously documented for iodinated contrast materials; however, the change in computed tomography density is not sufficient to have a clinically useful myelographic effect. Visible shortening of the T1 of CSF on gadolinium-enhanced magnetic resonance imaging of the spine may have clinical use. Twelve dogs were given gadolinium, and CSF was sampled at intervals over a 6-hour period. The T1 values of the CSF samples were quantitated and plotted against time. The average decrease in T1 was 23% at 60 minutes, which is nearly the peak effect. The increased signal intensity was visible at clinical window settings at 60 minutes. It is possible that this may be clinically useful for certain types of examinations. Importantly, this should be recognized as a normal appearance, and not necessarily a sign of pathology.     

Magnetic resonance angiography with gadolinium (Gd-DTPA) versus baseline magnetic resonance angiography in the study of the intracranial circulation]

The authors evaluated the role of GdDTPA in magnetic resonance angiography (MRA) of intracranial vessels. Fifteen patients affected with different conditions underwent MRA of intracranial vessels before and after paramagnetic contrast medium infusion. A superconductive 1.5-T magnet (Magnetom Siemens) was used, and a head circular coil, together with the 3DFT TOF technique. The enhanced exam was performed following the infusion of 0.2 ml/kg of GdDTPA in about 2 minutes, with simultaneous MRA image acquisition. To compare enhanced with unenhanced images relative to signal intensity, the signal increase at the basilar artery and carotid sinus was studied, together with signal-to-noise (S/N) ratio and spatial resolution. During acquisition, enhanced MRA images at the basilar artery showed a mean intensity value of 423.8 +/- 33.2 vs 357.8 +/- 53.2 of unenhanced scans; a statistically significant difference (p < 0.05; p < 0.01) was observed in favor of enhanced images. At the carotid sinus, enhanced MRA showed 184.5 +/- 28.4 mean intensity value vs 190.5 +/- 19.8 of unenhanced exams; no statistically significant difference was observed (p < 0.05; p < 0.01) in favor of unenhanced exams. At the basilar artery the S/N ratio of baseline exams was 1.9 vs 2.2 for enhanced scans; at the carotid sinus S/N ratio was 2.4 (unenhanced) vs 2.3 (enhanced). Thus, MRA allowed better visualization of peripheral branches of arterial (95.6%) and venous vessels, which unenhanced scans always failed to depict; on the other hand, enhanced images exhibited poorer definition of arterial vessels which were never isolated from the background. The simultaneous visualization of arterial and venous vessels, of choroid plexus and mucosae, affect the quality of enhanced angiograms. At present, GdDTPA is the sole contrast medium suitable for MRA intracranial vessels even though, due to its pharmacokinetic features, it is not the optimum medium.     

The developmental history of the gadolinium chelates as intravenous contrast media for magnetic resonance

The developmental history of the gadolinium chelates, which spans 30 years, is described, focusing, in part, on the seminal work with each of the major agents in use today. By examining this history, insight is gained into important issues of efficacy and safety, with valuable lessons to be learned from the mistakes made during this period. An overview of physicochemical characteristics and chemical structures is also provided. The review concludes with a discussion of current research directions involving this field, which is that of the intravenous contrast media for magnetic resonance, in the past 5 years.     

Dynamic imaging with magnetic resonance in the diagnosis of breast disease]

MR imaging was employed for the identification and tissue characterization of nodular lesions in the breast. The study had poor outcome, but the clinical introduction of a paramagnetic contrast medium, Gd-DTPA, allowed better results to be obtained. This study was aimed at evaluating the possibilities of Gd-DTPA enhanced MRI in differentiating benign from malignant breast nodules and in staging cancer. Final diagnosis was made by means of either histology, in the patients who underwent surgery, or cytology. Sixty-one patients with nodules at mammography and US were examined with MRI. The results of US, mammography, and MRI were blindly evaluated and proved that combined mammography and US, together with Gd-DTPA enhanced MRI, correctly identified all nodular lesions. Moreover, enhanced MRI allowed benign lesions to be distinguished from malignant nodules. MRI with Gd-DTPA correctly assessed both T parameter and pectoral muscle infiltration. MRI cannot replace mammography, which is a quick and inexpensive examination, but it should be performed as an adjunct in the cases of questionable radiographic and US findings and to stage breast cancer.     

心脏磁共振延迟强化技术进展

心脏磁共振（CMR）延迟强化是诊断心肌梗死、心肌病及评估病变范围最重要的检查技术。目前临床应用的单次激发相位敏感反转恢复（SS-PSIR）序列、自由呼吸运动伪影校正PSIR（MOCO-PSIR）序列和非血流依赖黑血延迟强化（FIDDLE）序列,相比常规采用的PSIR序列能够实现呼吸、心脏运动伪影及血池信号抑制,可明显改善影像质量,有利于更好地指导治疗并进行预后评价。就多种CMR延迟强化技术原理及应用作一综述。     

平山病的MRI诊断

目的：探讨平山病（hirayama disease）的MR影像学表现,提高对该病的认识。方法通过查阅相关文献,回顾性分析2例临床已确诊的平山病MR自然位和过屈位影像表现,观察其低位颈髓的动态变化,并与健康自愿者的同条件扫描影像相比较,总结平山病的MR影像学表现。结果①自然位：曲线多有异常,下段颈髓萎缩,髓内可有异常信号,有失连接现象;②过屈位：所有患者均出现颈髓前移、变扁,硬脊膜后有月牙形、集簇状异常信号影;③2例患者强化检查示过屈位脊膜后异常信号影有强化;④志愿者自然位扫描显示颈椎曲度自然,颈髓粗细均匀,不存在失连接现象,过屈位脊膜后无异常信号影。结论MR颈椎检查特别是过屈位扫描能够显示出平山病的特征性影像学改变,对于平山病的早期诊断具有重大价值。     

High-dose applications of gadolinium chelates in magnetic resonance imaging.

Administration of gadolinium chelates at doses greater than 0.1 mmol/kg IV can potentially improve both lesion detection and the assessment of tissue perfusion. Preliminary results are presented in clinical patients and two animal models. In human intracranial metastatic disease, administration of 0.3 (cumulative dose) mmol/kg gadoteridol (Gd HP-DO3A) has permitted detection of additional lesions not visualized at 0.1 mmol/kg. In a rabbit model of focal liver disease, 0.5 mmol/kg IV provided superior enhancement of both normal parenchyma and lesion rim compared to doses of 0.25 and 0.1. Dynamic imaging (T1-weighted turbo-FLASH) immediately following bolus injection of 0.5 mmol/kg permitted direct visualization (on unsubtracted images) of an acute perfusion defect in the cat brain not visible on conventional T1- and T2-weighted scans.     

心脏MRI在扩张型心肌病中的应用价值

目的 探讨1.5T心脏磁共振成像(CMRI)在扩张型心肌病(DCM)中的应用价值.方法 选取DCM患者45例及健康对照者25例,均进行CMRI检查,通过LGE序列判断左心室有无心肌纤维化将DCM组患者分为LGE(+)组和LGE(-)组,测如下结构及功能参数:LVEDD、LVESD、LVEDV、LVESV、LVEF、LV...     

Nanotemplate-engineered nanoparticles containing gadolinium for magnetic resonance imaging of tumors

PURPOSE: To design nanoparticles containing accessible gadolinium atoms (Gd-NPs) as a contrast agent for magnetic resonance imaging of tumors. METHODS: Nanoparticles containing phospholipid-chelates (phosphoethanolamine diethylenetriaminepentaacetate) and DSPE-PEG (MW5000) were prepared from Brij 78 and stearyl alcohol using the nanotemplate engineering approach. After addition of GdCl3, the presence of gadolinium on the surface of nanoparticles was quantified using inductively coupled plasma atomic emission spectroscopy. The in vitro relaxivities of the Gd-NPs in phosphate buffered saline were assessed at 4.7 T. The conditional binding constants of nanoparticle formulations were determined spectrophotometrically by competitive titration. Transmetallation kinetics of Gd from nanoparticles with Cu2+ and Zn2+ as the competing ions was measured in acetate buffer. The biodistribution profiles, pharmacokinetics, and contrast enhancement in tumor region was studied after administration of Gd-NPs to nude mice bearing A549 lung carcinoma xenografts. RESULTS: Gd-NPs with an average diameter of 138 nm possessing surface chelating functions were prepared from GRAS (generally regarded as safe) materials. The longitudinal relaxivity (r1) and transverse relaxivity (r2) of Gd-NPs in 10% fetal bovine serum at 4.7 T were 7.1 (+/-0.2) and 13.0 (+/-0.7) 1/mM/s, respectively. These pegylated Gd-NPs had enhanced relaxivities and exhibited particle size stability, sufficient binding affinity, and kinetic inertness under physiologic conditions. The contrast enhancement in tumors was demonstrated 40, 120, and 360 minutes after intravenous injection of Gd-NPs at a dose of 0.1 mmol Gd/kg. The Gd plasma concentration of Gd-NPs over a period of 24 hours fit a two-compartmental model with Cl sys = 0.89 mL/h and MRT = 5.93 h. The amount of Gd that accumulated in the tumor region was consistent with the estimated value obtained by T1 measurements using MR imaging. CONCLUSION: Pegylated nanoparticles composed of biocompatible, biodegradable materials and possessing accessible Gd ions on their surface induce relaxivities in the bulk water signal and accumulated sufficiently in tumors, demonstrating their utility as potential magnetic resonance imaging tumor contrast enhancement agents.     

Infectious spondylodiscitis: magnetic resonance imaging in HIV-infected and HIV-uninfected patients.

OBJECTIVE: We retrospectively reviewed 21 infections of the spine to correlate magnetic resonance imaging (MRI) with etiology of spondylodiscitis according to HIV status. CONCLUSION: MRI allowed the differentiation between tuberculous and pyogenic spondylodiscitis in the chronic stage. Typical findings were not observed in HIV+ as compared with HIV- patients, either concerning etiology or characteristic features of the spondylodiscitis.     

大脑胶质瘤病磁共振成像结合磁共振波谱成像的诊断价值

目的：探讨磁共振成像（MRI）结合磁共振波谱成像（MRS）对大脑胶质瘤病的诊断价值。方法对15例经活体组织检查或手术病理证实的大脑胶质瘤病患者的临床表现及MRI平扫、增强,MRS影像学资料进行回顾性分析。MRI常规行T1WI、T2WI及FLAIR序列,采用时间飞跃法（TOF）的磁共振血管成像（MRA）,T1WI增强扫描。氢质子MRS采用单体素STEAM序列,并分析N-乙酰天门冬氨酸（NAA）、肌酸（Cr）、胆碱复合物（Cho）等物质峰值改变。结果所有病例均侵犯2个或2个以上脑叶,以颞叶、枕叶、胼胝体、基底节和丘脑等部位侵犯受累常见。病变区T1WI呈低或等低信号、T2WI呈高或混杂高信号、FLAIR上为高信号,未见明显坏死、钙化,受累区域脑组织肿胀,占位效应轻。注射钆喷酸葡胺增强扫描示10例无明显强化、3例斑片状强化、1例结节状强化、1例线状轻度强化。病变区域MRS表现为不同程度NAA降低,NAA/Cr比值降低;Cho上升,Cho/Cr和Cho/NAA的比值上升。结论 MRI结合MRS对大脑胶质瘤病的诊断及鉴别诊断具有临床价值,是目前诊断大脑胶质瘤病的首选影像学方法。     

Magnetic resonance in the study of spondylodiscitis

Spondylodiscitis is an uncommon pathologic condition whose diagnosis can be difficult due to its aspecific clinical and radiological signs, especially in its early phase. Seventeen patients were examined in order to evaluate MR diagnostic capabilities. They had cervical (2 cases), thoracic (3 cases) and lumbosacral (12 cases) spondylodiscitis. All patients previously underwent conventional X-ray examination and CT; bone scintigraphy was performed in 9 cases. The final diagnosis was reached by needle aspiration (10 cases), by blood culture (2 cases), or according to clinical evolution (5 cases). MR was highly sensitive in identifying the disease, also in its early stages. Moreover, MR allowed the definition of phlogistic process extent and its relationship with intersomatic disk: signal alterations were limited to the vertebral bodies and to the disk in 3 cases; endocanalar spread of phlogistic process was observed in 8 cases; extravertebral soft tissues were involved in 1 patient; involvement of both canal and paravertebral soft tissue was found in 5 patients. Signal alterations in vertebral bodies and disks, together with the good topographic evaluation obtained with MR imaging, allowed a reliable diagnosis of spondyloscitis to be reached.     

The importance of magnetic resonance tomography in the diagnosis and staging of renal cell carcinoma]

The use of magnetic resonance imaging (MRI) for diagnosis and preoperative staging of renal cell carcinoma was evaluated in 79 patients with 88 tumors. Gradient-echo and spin-echo images before and after intravenous administration of Gadolinium-DTPA were compared with the results of computed tomography (CT) and histologic staging. The two imaging techniques had comparable results: T-stage was predicted correctly with CT in 78.4% and with MRI in 84.0% of the cases, while the N-stage was accurately assessed in 81.8% and 79.5%, respectively. MRI had some advantages in diagnosing perirenal tumor spread and in excluding an infiltration beyond Gerota's fascia. Therefore, MRI is a true alternative to CT for staging large renal cell carcinomas and especially for patients with contraindications for iodinated contrast agents.     

Computed tomography vs. magnetic resonance in the diagnosis of anorectal anomalies]

Anorectal malformations include a variety of anatomical anomalies which are often difficult to assess. Thirty-four patients (age range: 1 month-19 years) were studied over a 4-year period, 14 of them preoperatively and 20 postoperatively. In addition to inverted lateral plain films, a barred Iopamiro enema was performed in 13 of 14 cases by a Foley's catheter via colostomy. Endocolic pressure could thus be increased, which allowed the detection of rectal fistulas in 11 of 13 cases. Preoperative CT was performed in 9 cases, and MRI in 5. Both CT and axial MR scans provided accurate images of sphincteric muscles: they were well developed in 7 patients and poorly developed in 6; in 1 case the muscles were not identified. Sagittal MR scans only demonstrated the distance between blind pouch and perineum. Sagittal MRI also provided images of the spine (1 patient exhibited tethered cord). In the postoperative management, except for severe sacral anomalies, miscentered puborectal muscle and hypoplastic musculature were observed as the most frequent causes of fecal incontinence in patients treated with abdomino-perineal pull-through of the colon. To select the cases who needed reoperation, most frequently secondary PSARP, 17 patients were studied by CT and 7 by MRI; both techniques were employed in 4 cases. In 6 patients good development of sphincteric musculature and neo-anorectum correctly positioned within were observed. In 4 cases the neo-anorectum was correctly positioned, but sphincteric muscles were too hypoplastic to allow good continence; in 10 patients with incontinence, the neo-anorectum was seen outside sphincteric musculature: in 2 cases the latter was well developed (1 patient had had severe surgical damage to levator ani), while in 8 it appeared to be poorly developed. In our experience, postoperative CT allowed a correct evaluation to be made, whereas MRI failed to yield additional information.     

The magnetic resonance characteristics of rounded atelectasis]

Rounded atelectasis is a peculiar form of lung collapse which is well known by radiologists. Its appearance on conventional radiographs and CT is by now well recognized and widely reported. Even though these two techniques usually allow a diagnosis to be made, the MR appearance of rounded atelectasis is worth mentioning as well. This diagnostic imaging technique is widely employed, and our experience suggests that, in some cases, MR Imaging can give an important contribution to the study of this condition. We report our experience with 6 cases of rounded atelectasis in 5 patients (one patient had bilateral lesions). Five signs characteristic of rounded atelectasis were observed: some of them are seen on both conventional radiographs and CT scans, others are typical of the latter technique. All cases showed peripheral location of the lesions and the "comet tail" sign--i.e., vascular structures gently curving into the mass. These two signs are also observed on conventional radiographs and CT scans. Typical of MR imaging are the extant 3 signs: low signal in T1 and high signal in T2-weighted images in the whole of our cases; no signal from pleural thickening next to the mass in T2-weighted images, and, finally, the "kidney-like" pattern--i.e., hypointense lines converging toward the center of the mass. All these signs, which were always observed in our series, support the current etiopathogenetic hypothesis of pleural effusion as an early sign, which is reported to be followed by fibrous pleural involution which wraps atelectatic parenchyma up. On the basis of these typical MR features a correct diagnosis can usually be made even in those cases in which conventional radiography and CT do not allow a definite diagnosis.     

Brucellar spondylodiscitis: magnetic resonance imaging features with conventional sequences and diffusion-weighted imaging

Purpose

In this retrospective study, we evaluated the contribution and role of diffusion-weighted imaging (DWI) in differentiating acute and chronic forms of brucellar spondylodiscitis. We also describe the characteristics and some indistinguishable features of brucellar spondylodiscitis on magnetic resonance imaging (MRI) to emphasise the importance and limitations of MRI.

Materials and methods

MRI examinations of 25 patients with brucellar spondylodiscitis were retrospectively reviewed and analysed by two experienced radiologists. Signal and morphological changes were assessed. The imaging characteristics of acute and chronic forms of spondylodiscitis were compared. Both discriminative imaging findings of brucellar spondylodiscitis and some uncommon findings were interpreted.

Results

Of 25 patients with spinal brucellosis, eight had thoracic, ten had lumbar, five had both thoracic and lumbar and two had both lumbar and sacral vertebral involvement. We detected posterior longitudinal ligament elevation in 11 patients, epidural abscess formation in 11 and paravertebral abscess formation in nine. Ten patients had cord compression and eight had root compression. Three patients had facet-joint involvement, and one had erector spinae muscle involvement. Eight patients (32%) were in the acute stage, six (24%) in the subacute stage and 11 (44%) in the chronic stage. Vertebral bodies, vertebral end plates and intervertebral disc spaces were hypointense and hyperintense in the acute stage, whereas they were hypointense and heterogeneous in the subacute and chronic stages on T1- and T2-weighted images, respectively. In the acute stage on the DWI series, vertebral bodies, end plates and discs were all hyperintense but hypointense in the chronic stage.

Conclusions

Although conventional MRI has several advantages over other imaging modalities and is very useful in the differential diagnosis between brucellar spondylodiscitis and other spinal pathologies, it has some difficulties in discriminating acute and chronic forms of spondylodiscitis. DWI is a sensitive, fast sequence that has the potential for differentiating acute and chronic forms of spondylodiscitis, which makes it crucial in spinal imaging.     

The value of magnetic resonance tomography in the detection and differential diagnosis of focal liver lesions]

Magnetic resonance imaging (MRI) of the liver has made considerable progress due to improvements in the examination technique. Sensitivity for the detection of focal liver lesions is higher for MRI than for CT. In the differential diagnosis of liver tumors MRI is remarkably accurate. This is particularly true for hemangiomas, liver cell carcinomas and focal nodular hyperplasias. From a clinical view point differentiation between hemangiomas and metastases is of utmost importance. Future improvements in MR diagnosis of liver diseases are expected due to fast imaging techniques and liver-specific contrast agents.