Multiple myeloma: appearance at MR imaging.

Magnetic resonance (MR) imaging examinations of the lumbar spine and clinical and laboratory findings in 32 patients with multiple myeloma were reviewed. On T1-weighted images, signal intensity (SI) of the vertebrae approximated that of muscle in 14 cases and was intermediate (between the SIs of muscle and fat) in 18. Definite foci of decreased SI were seen in eight cases (25%), and foci of increased SI, representing fatty infiltration, were seen in 12 (38%). On T2-weighted images, SI approximated that of muscle in 17 cases and was intermediate in 15. Definite foci of increased SI were seen in 17 (53%). Of 38 vertebral compression fractures (including 18 in nine additional patients), foci of abnormal SI consistent with tumor on either T1- or T2-weighted images were seen in 19 cases (50%). There was no correlation between MR imaging findings and laboratory or bone marrow findings. Foci of presumed tumor were better or exclusively shown on T2-weighted images in 11 of 17 patients (65%) with identifiable focal disease. Other suggestions of multiple myeloma on T1-weighted images may be the absence of fatty replacement or a generalized decrease in SI.     

Vertebral compression fractures: distinction between benign and malignant causes with MR imaging

Magnetic resonance (MR) imaging was performed on 64 patients with 109 vertebral compression fractures, the cause of which could not be determined from plain radiographs. Twenty-five fractures were due to malignancy; 84 were caused by a benign process. In 22 of the 25 fractures caused by malignancy, MR images showed complete replacement of normal bone marrow, whereas 47 of the 61 benign fractures without history of trauma had complete preservation of normal bone marrow. The remaining 14 benign fractures had incompletely preserved bone marrow in a regular pattern. In two of the three remaining malignant fractures, the bone marrow replacement also was incomplete but with an irregular pattern. In cases of recent trauma or primary bone marrow abnormalities, the configuration and signal of remaining bone marrow were not useful in differentiating among malignancy, osteoporosis, and other benign processes. When criteria based on complete loss or preservation of marrow and marrow configuration in cases of incomplete loss were used, the accuracy in differentiating benign from malignant fractures was 94%. MR imaging may be a useful adjunct in differentiating benign from metastatic fractures and may provide information not available with other imaging methods.     

Acute osteoporotic and neoplastic vertebral compression fractures: fluid sign at MR imaging

PURPOSE: To evaluate the occurrence, location, and shape of the fluid sign in acute osteoporotic and neoplastic vertebral compression fractures at magnetic resonance (MR) imaging. MATERIALS AND METHODS: The study group comprised 87 consecutive patients with acute vertebral compression fractures due to osteoporotic (n = 52) or neoplastic (n = 35) infiltration. The MR imaging protocol included nonenhanced T1-weighted spin-echo and short inversion time inversion-recovery sequences and a 1.5-T system. Readers blinded to the outcome documented the occurrence, shape, and location of the fluid sign with consensus. The fluid sign was correlated with the cause, age, and severity of the fracture. The diagnosis was confirmed with surgery, follow-up MR imaging, clinical follow-up, or unequivocal imaging findings. Wilcoxon and chi(2) tests were used to assess significance. RESULTS: In fractured vertebral bodies, the fluid sign was adjacent to the fractured end plates and exhibited signal intensity isointense to that of cerebrospinal fluid. The fluid sign was linear (n = 16), triangular (n = 5), or focal (n = 2) and was significantly associated with osteoporotic fractures (21 [40%] of 52; P <.001). The fluid sign occurred in two (6%) of 35 neoplastic compression fractures. Histologic examination demonstrated osteonecrosis, edema, and fibrosis at the site of the fluid sign. There was a tendency toward older fractures exhibiting the fluid sign, but this relationship was not significant (P >.05). In osteoporotic fractures, the fluid sign was significantly associated with fracture severity (P <.05). CONCLUSION: The fluid sign is featured in acute vertebral compression fractures that show bone marrow edema. It can be an additional sign of osteoporosis and rarely occurs in metastatic fractures.     

Acute vertebral compression fractures in patients with multiple myeloma: evaluation of vertebral body edema patterns on MR imaging and the implications for vertebroplasty

The presence of edema on MR imaging is a common finding in acute or subacute vertebral body compression fractures. Compression fractures can present in patients with benign osteoporosis, metastases, multiple myeloma, or hemangiomas. We present 2 patients with multiple myeloma who had symptomatic acute and subacute compression fractures documented on imaging studies without associated edema on MR imaging evaluation.     

Prosthetic testicle: appearance at MR imaging

The appearance of testicular prostheses on magnetic resonance (MR) images was studied in six patients with seven silicone implants: two with a fluid consistency and five that were solid. On T1-weighted images, both types of prosthesis demonstrated homogeneous low signal intensity; on T2-weighted images, the fluid implants had a uniformly low signal intensity, and the solid implants had a uniformly high signal intensity. Both prostheses created a chemical shift artifact on all imaging sequences owing to the difference in chemical composition of the prostheses and the surrounding tissue.     

Endometriosis: appearance and detection at MR imaging

Thirty-nine magnetic resonance (MR) studies were performed on 31 women with surgically proved endometriosis. A total of 88 endometriotic lesions ranging in size from 0.2 to 7.5 cm were detected on 24 of 30 MR images of women. The signal intensities ranged from hyperintense on all pulse sequences (41 of 88) to hypointense on all sequences (24 of 88); the remainder demonstrated signal intensities corresponding to the appearances of acute, subacute, and chronic hematomas. Hypointense or signal-void rims on both T1- and T2-weighted images were detected in 35 lesions. Identification of the disease with MR imaging versus concurrent surgery was compared for 76 sites in 19 patients. Findings were true-positive in 24 cases, false-negative in ten, true-negative in 32, and false-positive in seven, resulting in an MR sensitivity of 71% and specificity of 82%. Adhesions obscured the disease at laparoscopy in three patients. MR imaging cannot be used as a substitute for laparoscopy in the definitive diagnosis or staging of endometriosis. However, it can be used to monitor treatment response in place of laparoscopy once a diagnosis is firmly established.     

Vertebral neoplastic compression fractures: assessment by dual-phase chemical shift imaging

PURPOSE: To compare normal vertebrae with vertebrae with neoplastic compression fractures by means of opposed-phase (OP) and in-phase (IP) gradient-echo (GRE) imaging. MATERIALS AND METHODS: On OP and IP T1-W GRE images (obtained at 1.5 T with the fast low-angle shot (FLASH) technique) of dual-phase chemical shift sequences, we compared the signal intensity ratios (SIRs) of normal and compression-fractured vertebrae in 108 patients. Dual-phase chemical shift sequences were measured in three groups of vertebral bone marrow in terms of the relative SIR in OP and IP images: group 1: normal vertebrae (N = 30 with 90 vertebrae); group 2: non-neoplastic compression-fractured vertebrae (N = 58 with 73 vertebrae); and group 3: neoplastic compression-fractured vertebrae (N = 20 with 27 vertebrae). The presence of compressed vertebrae was ascertained based on the consensus of two experienced radiologists. The mean SIRs among the three groups were compared by means of the Tukey-Kramer test. RESULTS: The mean SIRs of the three groups (group 1: 0.46 +/- 0.14; group 2: 0.63 +/- 0.21; and group 3: 1.02 +/- 0.11) were significantly different according to the Tukey-Kramer test (P < 0.01). CONCLUSION: OP and IP T1-W GRE MRI of vertebral SI abnormalities can help predict the nature of compression fractures.     

长期血液透析患者肩关节MRI表现

目的:观察透析患者骨内损伤病灶的信号模式,评估冈上肌腱增宽对长期血液透析患者的诊断价值。方法:16例透析患者和16名健康志愿者进行MR检查,测量MR下肩关节冈上肌腱宽度。统计SE序列T1、T2加权像下骨内损伤病灶的信号模式。结果:透析组冈上肌腱宽度4.5～11.7mm;健康组冈上肌腱宽度3.6～5.9mm,存在显著差异(P(0.05)。骨内损伤病灶在MR T2加权像下呈低信号(5/12)、高信号(1/12)及混杂信号(6/12)。结论:长期血液透析患者经常可见冈上肌腱增宽,当MR下冈上肌腱宽度超过6mm时,可提示存在淀粉样蛋白沉积可能。冈上肌腱增宽程度与透析时间存在明显相关性。骨内损伤病灶在MR T2加权像下信号模式多种多样。     

Myxoid liposarcoma: appearance at MR imaging with histologic correlation.

Although myxoid liposarcoma is a subtype of liposarcoma, it may be difficult to establish the correct diagnosis with magnetic resonance (MR) imaging due to the lack of fat signal intensity. Without the administration of gadolinium contrast material, the tumor may even mimic a cystic tumor. A spectrum of MR imaging abnormalities occur in myxoid liposarcoma, depending on the amount of fat and myxoid material, the degree of cellularity and vascularity, and the presence of necrosis. Most myxoid liposarcomas have lacy or linear, amorphous foci of fat. Some myxoid liposarcomas appear to be cystic at nonenhanced MR imaging, although they enhance like other solid masses at contrast material-enhanced MR imaging. The enhancing areas within the tumor represent increased cellularity and vascularity; the nonenhancing areas represent necrosis, reduced cellularity, and accumulated mucinous material. Gadolinium-enhanced imaging is important in differentiating myxoid liposarcoma from benign cystic tumors. Characterization of the tumor with MR imaging plays an important role in the management of myxoid liposarcoma.     

Urinary bladder MR imaging. Part I. Normal and benign conditions

The normal urinary bladder and several benign entities of the bladder were examined in 50 patients by magnetic resonance (MR) imaging. Specific features assessed included appearance of the bladder wall, optimal repetition (TR) and echo delay (TE) parameters for bladder-wall demonstration, and differentiation among various benign abnormalities, including bladder-wall hypertrophy, inflammation, and mucosal congestion, on MR images. The bladder wall in the 30 healthy subjects was best displayed using a TR = 2 sec, TE = 56 msec image, which gave 60% contrast between the bladder wall and urine and 48% contrast between the bladder wall and fat. Demonstration of bladder-wall hypertrophy required similar imaging; bladder distention was necessary to demonstrate the thickness of the bladder wall. Congestion and inflammation were best demonstrated on TR = 2 sec, TE = 56 msec images, which gave 45% contrast. Normal and/or hypertrophic bladder wall were distinguished from inflammation and congestion on the basis of signal intensity variations and/or T1 and T2 relaxation parameters.     

Neck neoplasms: MR imaging. Part I. Initial evaluation

Untreated neoplasms of the neck (tumors of the oropharynx, supraglottic area, carotid body, and thyroid, in addition to malignant lymphadenopathy) were evaluated in 23 patients with magnetic resonance (MR) imaging. The results were compared with computed tomographic (CT) scans in 20 patients. Contrast between tumor and fat was best on relatively T1-weighted images (500/30-35 [TR msec/TE msec]), whereas separation of tumor and muscle was best with relatively T2-weighted pulse sequences (1,500/90). Balanced images (1,500/30-35) provided best overall image quality and best demonstrated vascular anatomy. MR imaging was usually superior to CT in showing the relationship of tumor mass to muscle. MR imaging and contrast material-enhanced CT were equivalent in most patients in defining vascular anatomy, but MR imaging was superior when intravenous contrast material was not administered. However, CT was more helpful in showing bone and cartilage anatomy, and in some patients CT also was better in showing airway abnormalities. Despite these limitations, MR imaging is a promising imaging technique for studying neoplasms of the neck.     

Carpal tunnel: MR imaging. Part I. Normal anatomy

To correlate the important structures of the carpal tunnel demonstrated on magnetic resonance (MR) images with gross anatomy, the authors imaged the wrists of 20 normal volunteers and nine cadavers. The cadaver specimens were sectioned in the same planes in which they were imaged, and three other specimens were dissected. The anatomy was directly correlated with the imaged morphology. Axial images delineated well the bone and ligament walls of the carpal tunnel. The median nerve was well delimited and of moderate signal intensity. It was surrounded in some cases by fat but was consistently bound by specific tendons. The ulnar nerve and artery were visualized as they traversed the Guyon canal to their division into superficial and deep branches. Coronal images permitted optimal visualization of the triangular fibrocartilage and the radial and ulnar collateral ligaments. Quantitative studies indicated that the normal median nerve does not significantly increase in size within the carpal tunnel but does become more flattened at the level of the pisiform bone. The normal flexor retinaculum may have a slight palmar bowing.     

MR imaging of the knee. Part I. Traumatic disorders

One hundred thirty patients with a diversity of knee joint injuries were evaluated with a high-resolution magnetic resonance (MR) imaging technique. The authors report the accuracy of this technique in the evaluation of 105 patients with suspected meniscal tears, 26 patients with suspected cruciate ligament tears, and eight patients with suspected patellar tendon injuries. Of those menisci rated as definitely or probably torn on MR imaging, 80% were found to be torn at subsequent arthroscopy. The predictive value of negative MR imaging results was 100%. MR imaging was 92% accurate in predicting the clinical outcome in patients with suspected meniscal tears who did not undergo surgery. MR permitted complete disruption of the patellar tendon to be differentiated from partial tears, ligamentous inflammation, and localized effusion of the infrapatellar bursa. Injuries to the anterior and posterior cruciate ligaments were identified on MR images, and the status of synthetic grafts of the anterior cruciate ligament was ascertained.     

Discrimination of metastatic from acute osteoporotic compression spinal fractures with MR imaging.

A study was performed to determine which magnetic resonance (MR) imaging findings are useful in discrimination between metastatic compression fractures and acute osteoporotic compression fractures of the spine. The MR imaging findings in 27 patients with metastatic compression fractures and 55 patients with acute osteoporotic compression fractures were compared by using the chi(2) test. MR imaging findings suggestive of metastatic compression fractures were as follows: a convex posterior border of the vertebral body, abnormal signal intensity of the pedicle or posterior element, an epidural mass, an encasing epidural mass, a focal paraspinal mass, and other spinal metastases. MR imaging findings suggestive of acute osteoporotic compression fractures were as follows: a low-signal-intensity band on T1- and T2-weighted images, spared normal bone marrow signal intensity of the vertebral body, retropulsion of a posterior bone fragment, and multiple compression fractures. The signal intensity on fast spin-echo T2-weighted images obtained without fat suppression played little role in distinguishing between metastatic compression fractures and acute osteoporotic compression fractures. Copyright RSNA, 2003.     

MR弥散技术对脊柱压缩性骨折诊断价值初探

目的：初步评价MR弥散技术对脊柱单纯性和病理性压缩性骨折的诊断价值。方法：7l例脊柱椎体压缩性骨折行X线、MRI平扫和弥散序列检查(35例加作增强扫描)，其中53例另作CT检查。病理性骨折38例(包括转移性肿瘤29例，骨髓瘤4例，嗜酸性肉芽肿2例，结核3例)；单纯性分析33例(包括单纯外伤所致18例，骨质疏松所致l5例)。病理性分析者行CT引导下经皮骨穿刺检查或手术病理证实；外伤或骨质疏松所致椎体压缩性骨折均符合临床、实验室检查及MRI表现，部分经随访证实。结果：急性单纯性压缩性骨折和病理性骨折在常规MRI上有各自的特点。9％(3／33)单纯性压缩性骨折在DWI表现为等低信号混有条状高信号；24％(8／33)表现为等低信号；67％(22／33)表现为高信号。93％(36／38)病理性椎体压缩性骨折DWI上表现为高信号；7％(2／38)表现为等低信号。DWI上均至高信号的单纯性压缩和病理性压缩经统计分析无显著性意义(P＞0．05)。结论：单凭MRI弥散序列的信号改变不能非常准确地鉴别脊柱单纯性压缩性分析和病理性骨折，需进一步深入定量研究。     

Temporomandibular joint after meniscoplasty: appearance at MR imaging

Twenty-five temporomandibular joints (TMJs) were studied in 20 patients who had undergone meniscoplasty. In all patients, preoperative magnetic resonance (MR) images showed anteriorly dislocated disks; all patients underwent a similar postoperative MR examination an average of 6 months after surgery. The results of these studies were correlated with clinical results of surgery, which were classified as poor, fair, good, or excellent at follow-up MR imaging. In 10 TMJs (eight patients [40%]) the clinical results were excellent or good; in 15 TMJs (12 patients [60%]), fair or poor. The position of the disk relative to its preoperative position was a good discriminator in determination of the clinical success of meniscoplasty. After surgery, in all patients with good or excellent results, the disks appeared to be in a normal or an improved position compared with that prior to surgery; in those with poor or fair results, the TMJs had anteriorly dislocated disks that showed no improvement.