Infectious sacroiliitis: value of computed tomography (CT) and magnetic resonance imaging (MRI)

Infectious sacroiliitis is an uncommon septic arthritis, the diagnosis of which is difficult to establish. We retrospectively examined 14 cases of septic sacroiliitis, by CT (two of whom also had an MRI examination). The patient population consisted of eight men and six women; 9 were African, 8 had tuberculous sacroiliitis and 6 pyogenic sacroiliitis. All the cases showed a pre-sacroiliac soft tissue swellilng with ring-like enhancement following intravenous contrast in eight cases. A gas image was observed at the centre of the abcess in two cases. Joint narrowing was found in four patients and widening in eight, associated with an image of bone sequestration in seven, CT gave an etiologic orientation in 8 cases, and facilitated the guidance of bone biopsy. MRI showed low signal T1-weighted images and high signal T2 of the subchondral bone, joint space and soft tissue abcess. We conclude that CT is helpful in the evaluation of infectious sacroiliitis, and that further studies are necessary to evaluate the role of MRI in such pathologic processes.     

Comparison of supraspinatus tendon and glenohumeral joint axes in MR imaging of the shoulder

Objective. In magnetic resonance (MR) imaging of the shoulder, oblique coronal images are used for evaluating the supraspinatus tendon (SST) of patients with suspected rotator cuff tear or impingement. This study aimed to compare orientation of the SST long axis with planes perpendicular to the glenohumeral joint (GHJ). Design and patients. The axial scans of 100 consecutive patients referred for MR imaging or MR arthrography of the shoulder were reviewed. Using the electronic cursors of a computer workstation, the angle of the SST long axis was measured and compared with the angle obtained through the GHJ utilizing three different landmarks: perpendicular to the joint (GHJ-90), joint–humeral head center axis (GHJ-H) and joint–scapular body axis (GHJ-S). Results. Differences in angulation between axes of the SST and the three GHJ axes averaged only about 5° [range of means 4.5–5.3°, range of standard deviation (SD) 3.8–4.6°]. In the majority of shoulders, angular differences measured 4 or less for all SST/GHJ comparisons. Similarly, small angular differences in the three GHJ axes were found: 4.5° (SD 3.3°) for GHJ-90/GHJ-S, 5.0° (SD 4.0°) for GHJ-S/GHJ-H and 2.9° (SD 3.0°) for GHJ-90/GHJ-H. Correlation between the GHJ-90 and GHJ-H axes was particularly good, with differences of 4° or less in 84% of shoulders. The orientations of the GHJ axes and that of the SST long axis are comparable. Conclusion. The GHJ may potentially be used as a landmark for obtaining oblique coronal images of the SST. Received: 19 November 1999 Revision requested: 18 January 2000 Revision received: 27 March 2000 Accepted: 5 April 2000     

Magnetic resonance imaging of septic sacroiliitis

Five cases of septic sacroiliitis diagnosed by magnetic resonance imaging (MRI) are presented. Imaging was performed between 2 and 14 days after onset of symptoms and consisted of varying combinations of coronal short tau inversion recovery (STIR), axial T2-weighted spin echo (SE), and coronal and axial pre- and postcontrast T1-weighted SE scans. Abnormalities included demonstration of sacroiliac joint effusions, bone oedema and adjacent inflammation as high signal on STIR and T2-weighted SE scans, and identification of abscesses in two cases as rim-enhancing lesions anterior to the joint on gadolinium-enhanced T1-weighted SE scans. The role of MRI and other forms of imaging in septic sacroiliitis is discussed.     

Intra-articular gouty tophi of the knee: CT and MR imaging in 12 patients

Objective. To define the imaging characteristics of intra-articular tophi of the knee. Design and patients. Twelve patients with intra-articular tophi in the knee were studied with routine MR imaging, gadolinium (Gd)-enhanced MR imaging, and CT over a 4-year period. There were 11 men and one woman, 25–82 years of age (mean age 48 years). Four patients did not have a documented history of gout at the time of the MR examination. The diagnosis of intra-articular tophi was provided by arthroscopy and histological examination (5 patients), by microscopic study of joint fluid (5 patients), or by characteristic clinical, laboratory and imaging findings (2 patients). Results. In 15 MR examinations the tophi were located purely intra-articularly in 10 knees. In the remaining five MR studies, periarticular soft tissues or bone, or both, were involved. All the intra-articular tophi manifested low to intermediate signal intensity on both T1- and T2-weighted images. All five Gd-enhanced MR examinations demonstrated a heterogeneous peripheral enhancement. All 10 CT scans showed varying degrees of stippled calcifications within the tophi. The nature of the calcifications was confirmed on histological examination in three patients. Conclusion. Presenting clinical manifestations of gout may relate to intra-articular tophaceous deposits. Such deposits present as masses on MR images with low to intermediate signal intensity on both T1- and T2-weighted images and a characteristic enhancement pattern following intravenous Gd administration. These features relate primarily to internal calcifications, which are most evident on CT images. MR evaluation (including Gd administration) supplemented, in some cases, with CT scanning allows accurate diagnosis of intra-articular tophaceous deposits. Received: 24 August 1998; Revision requested: 1 October 1998; Revision received: 19 October 1998; Accepted: 23 October 1998     

MR imaging of articular cartilage

With the advent of new treatments for articular cartilage disorders, accurate noninvasive assessment of articular cartilage, particularly with MR imaging, has become important. Understanding the MR imaging features of articular cartilage has led to the development of two types of routinely available MR imaging techniques which have demonstrated clinical accuracy and interobserver reliability. Received: 25 January 2000 Revision requested: 21 March 2000 Revision received: 31 March 2000 Accepted: 3 April 2000     

MR imaging and CT in osteoarthritis of the lumbar facet joints

Objective. To test the agreement between MR imaging and CT in the assessment of osteoarthritis of the lumbar facet joints, and thus to provide data about the need for an additional CT scan in the presence of an MR examination. Design and patients. Using a four-point scale, two musculoskeletal radiologists independently graded the severity of osteoarthritis of 308 lumbar facet joints on axial T2-weighted and on sagittal T1- and T2-weighted turbo-spin-echo images and separately on the corresponding axial CT scans. Kappa statistics and percentage agreement were calculated. Results. The weighted kappa coefficients for MR imaging versus CT were 0.61 and 0.49 for readers 1 and 2, respectively. The weighted kappa coefficients for interobserver agreement were 0.41 for MR imaging and 0.60 for CT, respectively. There was agreement within one grade between MR and CT images in 95% of cases for reader 1, and in 97% of cases for reader 2. Conclusion. With regard to osteoarthritis of the lumbar facet joints there is moderate to good agreement between MR imaging and CT. When differences of one grade are disregarded agreement is even excellent. Therefore, in the presence of an MR examination CT is not required for the assessment of facet joint degeneration. Received: 12 June 1998 Revision requested: 20 October 1998 Revision received: 29 December 1998 Accepted: 14 January 1999     

The role of multi-parametric MR imaging in the detection of early inflammatory sacroiliitis according to ASAS criteria

Purpose

To retrospectively evaluate the accuracy of multi-parametric magnetic resonance (MR) imaging including fat saturated (FS) T2-weighted, short-tau inversion recovery (STIR), diffusion-weighted (DW-MR), and dynamic-contrast-enhanced MR (DCE-MR) imaging techniques in the diagnosis of early inflammatory sacroiliitis and determine the additional value of DW-MR and DCE-MR images according to recently defined ‘Assessment in SpondyloArthritis international Society’ criteria.

Materials and methods

The study included 45 patients with back pain. Two radiologists estimated the likelihood of osteitis in 4 independent viewing sessions including FS T2-weighted, STIR, DW-MR and DCE-MR images. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the receiver operating characteristic (ROC) curve (AUC) were calculated.

Results

Of the 45 patients, 31 had inflammatory back pain. Of 31, 28 (90.3%) patients had inflammatory sacroiliitis diagnosed by clinical and laboratory analysis. FS T2-weighted MR images had the highest sensitivity (42.8% for both radiologists) for detecting osteitis in patients with inflammaory sacroiliitis when compared to other imaging sequences. For specificity, PPV, NPV, accuracy, and AUC levels there were no statistically significant difference between image viewing settings. However, adding STIR, DW-MR and DCE-MR images to the FS T2-weighted MR images did not improve the above stated indices.

Conclusion

FS T2-weighted MR imaging had the highest sensitivity when compared to other imaging sequences. The addition of DW-MR and DCE-MR images did not significantly improve the diagnostic value of MR imaging in the diagnosis of osteitis for both experienced and less experienced radiologists.     

Silicone synovitis: MR imaging in five patients

 Silicone synovitis is a known complication of silicone implants used in orthopedic surgery for joint reconstruction. It has been studied with routine radiography; however, no report on magnetic resonance imaging abnormalities of this condition exist in the literature. This article reports on five patients with silicone synovitis studied by magnetic resonance imaging. All patients showed hypointense implants that were deformed, fragmented or subluxed, and intra- and periarticular silicone particles were evident on T1- and T2-weighted images.     

MR imaging of hyaline cartilage at 0.5 T: a quantitative and qualitative in vitro evaluation of three types of sequences

Objective. To identify an optimal pulse sequence for in vitro imaging of hyaline cartilage at 0.5 T. Materials and methods. Twelve holes of varying diameter and depth were drilled in cartilage of two pig knees. These were submerged in saline and scanned with a 0.5-T MR system. Sixteen T1-weighted gradient echo (GE), two T2-weighted GE, and 16 fast spin echo sequences were used, by varying repetition time (TR), echo time (TE), flip angle (FA), echo train length, profile order, and by use of fat saturation. Contrast-to-noise ratios (CNR) of cartilage versus saline solution and cartilage versus subchondral bone were measured. Cartilaginous lesions were evaluated separately by three independent observers. Interobserver variability and correlation between the quantitative and qualitative analyses were calculated. Results. The mean CNRs of two specimens of cartilage versus saline solution ranged from 6.3 (±2.1) to 27.7 (±2.5), and those of cartilage versus subchondral bone from 0.3 (±0.2) to 22.5 (±1.4). The highest CNR was obtained with a T1-weighted spoiled 3D-GE technique (TR 65 ms, TE 11.5 ms, FA 45°). The number of lesions observed per sequence varied from 35 to 69. Observer agreement was fair to good. The T1-weighted spoiled GE sequences with a TR of 65 ms, TE of 11.5 ms and FA of 30° and 45° were significantly superior to the other 34 sequences in the qualitative analysis. Conclusion. T1-weighted spoiled 3D-GE sequences with a TR of 65 ms, a TE of 11.5 ms, and a FA of 30–45° were found to be optimal for in vitro imaging of cartilage at 0.5 T.     

MR imaging of symptomatic osteochondromas with pathological correlation

Objective. To demonstrate the value of MR imaging in the diagnosis and differentiation of the various symptomatic complications of osteochondromas, providing pathological correlation with emphasis on the usefulness of MR imaging as a single imaging modality in these patients. Design. We retrospectively reviewed all MR examinations of clinically symptomatic osteochondromas (30 patients) performed at our institution between March 1990 and October 1997. Patients. Thirty patients had clinically symptomatic osteochondromas during the study period. Twenty patients were male and 10 were female. There were five cases of multiple osteochondromatosis. Pathological correlation was available in 24 patients. Results and conclusion . Symptomatic complications included fracture (7%), osseous deformity limiting range of motion (23%), vascular injury (7%), neurological compromise (10%), bursa formation (27%) and malignant transformation (27%). MR imaging was able to diagnose or suggest the etiology for the clinical symptomatology in all cases, demonstrating that it is an ideal imaging modality in the diagnostic evaluation of symptomatic complications of osteochondromas and often avoids the need for further imaging.     

Contrast-enhanced,ultrafast 3d pulmonary MR angiography in a single breath-hold: Initial assessment of imaging performance

An ultrafast three-dimensional (3D) sequence was developed, enabling the acquisition of 44 contiguous 2.0-to 2.2-mm thin sections, during intravenous application of paramagnetic contrast, in a single breath-hold. To estimate the potential clinical usefulness, images were assessed qualitatively and quantitatively with regard to visibility of main, lobar, segmental, and subsegmental pulmonary arteries. Five volunteers were examined using a 192 × 192 matrix with an imaging time of 23 seconds and five other volunteers with a 160 × 160 matrix (18 seconds). Each volunteer was imaged in apnea and during shallow respiration. The breath-held 23-second scans revealed excellent image quality and near complete visualization of central and segmental, as well as 81% of subsegmental, pulmonary arteries. Imaging time can be shortened to 18 seconds with only marginal loss in visualization performance (P < .05). Respiratory motion was found to cause significant worsening of image quality and vessel detectability. To maintain relevance in a clinical setting, imaging time can be minimized at the cost of a reduction in spatial resolution.     

MR imaging of articular cartilage in the ankle: comparison of available imaging sequences and methods of measurement in cadavers

 Objective. To assess hyaline cartilage of cadaveric ankles using different magnetic resonance (MR) imaging techniques and various methods of measurement. Design and patients. Cartilage thicknesses of the talus and tibia were measured in ten cadaveric ankles by naked eye and by digitized image analysis from MR images of fat-suppressed T1-weighted gradient recalled (FS-SPGR), sequences and pulsed transfer saturation sequences with (FS-STS) and without fat-suppression (STS); these measurements were compared with those derived from direct inspection of cadaveric sections. The accuracy and precision errors were evaluated statistically for each imaging technique as well as measuring method. Contrast-to-noise ratios of cartilage versus joint fluid and marrow were compared for each of the imaging sequences. Results. Statistically, measurements from FS-SPGR images were associated with the smallest estimation error. Precision error of measurements derived from digitized image analysis was found to be smaller than that derived from naked eye measurements. Cartilage thickness measurements in images from STS and FS-STS sequences revealed larger errors in both accuracy and precision. Interobserver variance was larger in naked eye assessment of the cartilage. Contrast-to-noise ratio of cartilage versus joint fluid and marrow was higher with FS-SPGR than with FS-STS or STS sequences. Conclusion. Of the sequences and measurement techniques studied, the FS-SPGR sequence combined with the use of digitized image analysis provides the most accurate method for the assessment of ankle hyaline cartilage.     

强直性脊柱炎骶髂关节影像学分析(附24例骶髂关节平片、CT和MR影像对比观察)

目的：旨在评估强直性脊柱炎（ＡＳ）患者骶髂关节炎的ＭＲ影像特征，并比较Ｘ线平片、ＣＴ和ＭＲ影像在诊断骶髂关节炎中的作用。材料与方法：搜集２４例ＡＳ患者，分别行Ｘ线平片、ＣＴ和ＭＲＩ检查。增强前ＭＲ扫描序列包括ＳＥＴ１ＷＩ、ＦＳＥＴ２ＷＩ和梯度回波的准Ｔ２ＷＩ（ＧＲＴ２＊ＷＩ）。增强后ＭＲ扫描序列参数与增强前ＳＥＴ１ＷＩ相同。另选９例志愿者，行ＭＲ平扫检查。结果：８例志愿者１６个骶髂关节的Ｔ１ＷＩ和Ｔ２ＷＩ可直接显示正常骶髂关节软骨，表现为线形或点样的中等信号影。９例志愿者１１个骶髂关节的骨髓内可见局灶性脂肪沉积。２４例ＡＳ患者的４２个骶髂关节可见软骨异常，表现为Ｔ１ＷＩ和Ｔ２ＷＩ上正常线形中等信号的软骨影像消失，代之以不规则增粗或扭曲样中等信号。分析表明：在骶髂关节炎的诊断方面，ＭＲ和ＣＴ明显优于Ｘ线平片（Ｐ＜０．００１）。结论：同Ｘ线片比较，虽ＣＴ和ＭＲＩ均有助于ＡＳ骶髂关节炎的诊断，但ＭＲ影像可显示ＣＴ和Ｘ线所不能显示的软骨异常和骨髓内水肿改变；骨髓内脂肪沉积可属正常变异；扭曲样中等强度信号应视为软骨的异常征象。     

T_2~*-mapping用于青年志愿者骶髂关节软骨成像的初步研究

目的通过优化扫描参数及后处理技术,定量分析正常骶髂关节(SIJ)软骨T2*弛豫时间值,探讨磁共振T2*-mapping成像用于青年健康志愿者SIJ软骨研究的可行性,为下一步AS患者SIJ软骨T2*-mapping研究奠定基础。方法采用3.0T超导磁共振扫描仪,随机选取2013年12月~2014年3月期间青年健康志愿者30名,对其行5回波GRE序列双侧SIJ斜冠状面扫描,运用T2*图测量30例骶侧软骨平均T2*弛豫时间值,并进行统计学分析。结果 30名青年健康志愿者骶侧软骨T2*弛豫时间值平均为(17.15±3.26)ms。30名正常青年健康志愿者中,15名男性和15名女性骶侧软骨T2*弛豫时间值分别约为(18.66±3.17)ms和(15.65±2.62)ms,差异有统计学意义(t=4.005,P0.05)。30名正常青年健康志愿者中,左侧和右侧骶侧软骨T2*弛豫时间值分别约为(17.26±3.51)ms和(17.05±3.04)ms,差异没有统计学意义(t=0.516,P0.05)。结论 T2*-mapping成像可用于测量正常青年人SIJ骶侧软骨的T2*值,可为临床骶髂关节炎(SIS)疾病的诊断和研究提供参考。由于SIJ髂侧面软骨太薄,T2*-mapping成像应用于SIJ髂侧面软骨研究仍面临挑战。     

Reactive synovitis of the knee joint: MR imaging appearance with arthroscopic correlation

Objective. To evaluate the use of routine MR imaging sequences in detecting and characterizing secondary reactive synovitis of the knee joint using arthroscopy as the standard of reference. Design and patients. Fifty consecutive patients with a history of knee pain who were referred for MR imaging and subsequently underwent arthroscopy of the knee comprised the study group. MR images were evaluated for the presence and appearance of synovitis reflected in synovial thickening and irregularity. Synovial thickening was graded on MR imaging as follows: 0=normal, 1=thin line of increased signal intensity, 2=increased signal intensity with frond-like or hair-like projections and a granular appearance of joint fluid. Standard knee imaging protocols were used. Results. The sensitivity, specificity, and accuracy of MR imaging in detecting synovitis compared with arthroscopy were 88%, 97%, and 95%, respectively. Grade 1 synovitis was best seen on proton-density-weighted images, demonstrating increased signal intensity of the synovium against the relatively low signal intensity of the joint fluid. Grade 2 synovitis was best seen on proton-density images and T2-weighted spin echo and fast spin echo images with fat saturation, demonstrating a granular and linear hair-like appearance of joint fluid. Axial and sagittal imaging planes were most helpful in the diagnosis of synovitis. Conclusion. Routine MR pulse sequences are useful in identifying the presence and extent of synovial abnormalities. The detection of different stages of synovial pathology should become an important part of the evaluation of the post-traumatic patient as treatment may be altered as a result. Received: 17 March 2000 Revision requested: 5 May 2000 Revision received: 8 June 2000 Accepted: 8 June 2000     

Color flow-encoded MR imaging.

Magnetic resonance phase images can enable identification of any type of motion, including the velocity and direction of flow, and thus provide valuable supplements to magnitude images, which depict stationary tissue most effectively. A method is described for the simultaneous display of phase and magnitude by color encoding the phase data and superimposing it on the magnitude image to facilitate clinical interpretation. Color-encoded data not only depict the location and direction of flow along specific axes but can also provide relative velocity information through shades of color. Implementation of the technique is described, and the factors to be considered during interpretation of color flow-encoded images are discussed.     

MR imaging for blunt pancreatic injury

Objective

To study the MR imaging features of blunt pancreatic injury.

Materials and methods

Nine patients with pancreatic injury related to blunt abdominal trauma confirmed by surgery performed MR imaging. Two abdominal radiologists conducted a review of the MR images to assess pancreatic parenchymal and pancreatic duct injury, and associated complications.

Result

Diagnostic quality MR images were obtained in each of the nine patients. In the nine patients, pancreatic fracture, laceration and contusion were depicted on MR imaging in five, one and three patients, respectively. There were six patients with pancreatic duct disruption, eight patients with peripancreatic fluid collections, and four patients with peripancreatic pseudocyst or hematoma, respectively. All of the MR imaging findings was corresponded to surgical findings.

Conclusion

MR imaging is an effective method to detect blunt pancreatic injury and may provide information to guide management decisions.     

Tendon shift in hallux valgus: observations at MR imaging

 Objective. This study was undertaken to demonstrate a shift in tendon alignment at the first metatarsophalangeal joint in patients with hallux valgus by means of magnetic resonance imaging. Design. Ten normal feet and 20 feet with the hallux valgus deformity conforming to conventional clinical and radiographic criteria were prospectively studied using magnetic resonance imaging. Correlation was made between tendon position at the first metatarsophalangeal joint and the severity of the hallux valgus deformity. Results. There is a significant shift in tendon position at the first metatarsophalangeal joint of patients with hallux valgus. The insertion of the abductor hallucis tendon is markedly plantarward and the flexor and extensor tendons bowstring at the first metatarsophalangeal joint compared with patients without the deformity. The severity of the tendon shift correlates with the hallux valgus angle and clinical severity of the hallux valgus deformity in each case. Conclusion. Patients with hallux valgus have a significant tendon shift at the first metatarsophalangeal joint which appears to contribute to development of the deformity.     

MR imaging of the Achilles tendon: overlap of findings in symptomatic and asymptomatic individuals

Objective: To differentiate MR imaging characteristics of symptomatic as compared with asymptomatic Achilles tendons. Design: 1.5 T MR images of 94 feet (88 patients) with ”abnormal” MR examinations were retrospectively evaluated and clinically correlated. Two masked, independent observers systematically evaluated for intratendon T2 signal, tendon thickness, presence of peritendonitis, retrocalcaneal bursal fluid volume, pre-Achilles edema, bone marrow edema at the Achilles insertion, and tears (interstitial, partial, complete). These findings were correlated with symptoms (onset and duration) and physical examination results (tenderness, palpable defects, increased angle of resting dorsiflexion). Results: Of the 94 ankles, 64 ankles (32 females, 29 males) were clinically symptomatic. No relationship between Achilles tendon disorders and age or gender was identified. Asymptomatic Achilles tendons frequently demonstrated mild increased intratendon signal (21/30), 0.747 cm average tendon thickness, peritendonitis (11/30), pre-Achilles edema (12/30), and 0.104 ml average retrocalcaneal bursal fluid volume. Symptomatic patients had thicker tendons (0.877 cm), greater retrocalcaneal fluid volume (0.278 ml), more frequent tears (23/64), a similar frequency of peritendonitis (22/64) but less frequent pre-Achilles edema (18/64). Sixty-four percent of the Achilles tendon tears were interstitial. Except for two interstitial tears in control patients, the majority of Achilles tears were in symptomatic patients (14/16). Only symptomatic tendons demonstrated partial or complete tendon tears. In addition, calcaneal edema was found almost exclusively in actively symptomatic patients. Thicker tendons were associated more often with chronic symptoms and with tears. When present in symptomatic patients, peritendonitis was usually associated with acute symptoms. The presence of pre-Achilles edema, however, did not distinguish acute from chronic disorders. Conclusion: There is significant overlap of MR findings in symptomatic and asymptomatic Achilles tendons. Furthermore, there is apparently a spectrum of disease in symptomatic tendons ranging from subtle intratendinous and peritendinous signal to partial and complete tendon tear. Received: 17 March 2000 Revision requested: 26 May 2000 Revision received: 19 July 2000 Accepted: 19 July 2000     

MR imaging of lumbar facet joint synovial cysts

The increasing application of magnetic resonance (MR) imaging of the spine has raised the awareness of lumbar facet synovial cysts (LFSC). This well recognised, yet uncommon condition, presents with low back pain and radiculopathy due to the presence of an extradural mass. The commonest affected level is L4/5 with a mild degenerative spondylolisthesis a frequent associated finding. MR imaging is the technique of choice to detect and diagnose a LFSC. This pictorial essay, drawing on experience of 43 cases seen in 40 patients, illustrates the spectrum of appearances that can be encountered and suggest differing causes for the variable signal characteristics exhibited. Computed tomography (CT) can be of value in some cases to aid interpretation of the MR images. In addition, CT facet arthrography by injection of air or iodinated non-ionic contrast medium may be used to confirm the diagnosis in doubtful cases as well as noting whether the patients presenting symptoms can be provoked. A comprehensive review of the existing literature is presented. Received: 22 September 1998; Revised: 29 June 1999; Accepted: 30 June 1999