Clinically significant skeletal variations of the shoulder and the wrist: role of MR imaging

Several skeletal variations of the upper extremity may cause painful conditions or precipitate early degenerative changes, either spontaneously or in response to overuse and trauma. Magnetic resonance imaging has proved particularly useful for accurate interpretation of many of these clinically significant skeletal variations; however, the widespread use of MR imaging may have contributed to over-emphasizing their clinical importance, which is still controversial in many cases. We review, illustrate, and discuss clinically significant skeletal variations of the upper extremity as seen on MR images, particularly those involving the shoulder and the wrist. In the shoulder region, we evaluate variations of acromial and coracoid processes as well as variations and minor dysplastic deformities of the glenoid fossa. We also review different skeletal variations of the carpal region, including ulnar variance, ulnar styloid, lunate morphology, carpal coalition, and carpal accessory ossicles. The role of MR imaging in assessing the clinical importance of such conditions, whether potential, controversial, or well established, is emphasized in this review.     

Magnetic resonance imaging of the wrist in rheumatoid arthritis: demonstration of progression between 1 and 6 years

Objective To describe the changes seen in the wrist in rheumatoid arthritis (RA) on magnetic resonance (MR) imaging obtained at 1 year and 6 years.Design A cohort of patients with RA has been studied prospectively from symptom onset.Patients MR scans of the dominant wrist in 31 patients obtained at 1 year and 6 years were compared for bone erosions, marrow signal change (oedema), synovial thickness and tenosynovitis.Results Twenty-two patients had an increase in erosion score in the interval and three patients showed a decrease in erosion score suggesting erosion healing. Fourteen patients had an increase in oedema score in the interval and eight patients had a decrease in oedema score. Synovial thickness increased in 13 patients and decreased in eight. Tenosynovitis increased in 15 patients and decreased in five. Bone erosions developed immediately adjacent to the tenosynovitis in two patients.Conclusions MR imaging is useful in following the progress of bone erosions, marrow oedema, synovitis and tenosynovitis in RA.     

Molecular MR Imaging for Visualizing ICAM-1 Expression in the Inflamed Synovium of Collagen-Induced Arthritic Mice

Objective

To determine the utility of intercellular adhesion molecule (ICAM)-1 antibody-conjugated gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA-anti-ICAM-1) as a targeted contrast agent for the molecular magnetic resonance imaging (MRI) in collagen-induced arthritis (CIA).

Materials and Methods

Three groups of mice were used: non-arthritic normal, CIA mice in both the early inflammatory and chronic destructive phases. The MR images of knee joints were obtained before and after injection of Gd-DTPA-anti-ICAM-1, Gd-DTPA, and Gd-DTPA-Immunoglobulin G (Ig G) and were analyzed quantitatively. The patterns of enhancement on the MR images were compared with the histological and immunohistochemical ICAM-1 staining.

Results

The images obtained after injection of Gd-DTPA-anti-ICAM-1 displayed gradually increasing signal enhancement from the moment following injection (mean ± standard deviation [SD]: 424.3 ± 35.2, n = 3) to 24 hours (532 ± 11.3), rather than on pre-enhanced images (293 ± 37.6) in the early inflammatory phase of CIA mice. However, signal enhancement by Gd-DTPA and Gd-DTPA-IgG disappeared after 80 minutes and 24 hours, respectively. In addition, no significant enhancement was seen in the chronic destructive phase of CIA mice, even though they also showed inflammatory changes on T2-weighted MR images. ICAM-1 expression was demonstrated in the endothelium and proliferating synovium of the early inflammatory phase of CIA mice, but not in the chronic destructive phase.

Conclusion

Molecular MRI with Gd-DTPA-anti-ICAM-1 displays specific images targeted to ICAM-1 that is expressed in the inflamed synovium of CIA. This novel tool may be useful for the early diagnosis and differentiation of the various stages of rheumatoid arthritis.     

Longitudinal changes in rheumatoid arthritis after rituximab administration assessed by quantitative and dynamic contrast-enhanced 3-T MR imaging: preliminary findings

We retrospectively assessed the longitudinal changes of rheumatoid arthritis under rituximab therapy by use of quantitative and dynamic contrast-enhanced 3-T magnetic resonance (MR) imaging of the metacarpophalangeal joints of 10 patients at baseline and 26 weeks (n = 10). Additional studies were available at 12 weeks (n = 9) and at 52 weeks (n = 5). Clinical activity was assessed by use of the 28-joint disease activity score (DAS28). MR imaging was used to assess volumes of synovial enhancement, osseous enhancement, and erosions and early rapid enhancement. DAS28 and serum C-reactive protein trended down over time and were significantly lower at 26 weeks. Volume of synovial enhancement and early rapid enhancement showed a significant minimum at 26 weeks and increased thereafter. The erythrocyte sedimentation rate paralleled these two trends. Osseous enhancement did not significantly change over time. Erosions showed a significant progression. Trends of DAS28 and erosions were significantly different (P = 0.0075). In conclusion, our preliminary results suggest that rituximab is associated with a decrease of the inflammatory activity of synovitis with a minimum at 26 weeks and increasing activity thereafter suggesting recurrence. Our results further suggest subclinical progression of erosions with an inverse relationship to decreasing disease activity scores. Further studies are needed to confirm these results.     

MR imaging of tuberculous arthritis: Clinical and experimental studies

Signal-intensity characteristics of magnetic resonance (MR) images were assessed in five patients and in 10 rabbits with tuberculous arthritis. MR imaging findings were compared with histologic findings in the animal study. In both of clinical and experimental cases, tuberculous lesions showed both intermediate and high signal intensity on T2-weighted images, while they showed heterogeneously intermediate signal intensity on T1-weighted images. As T2-weighted images were compared with pathologic specimens, intermediate signal intensity corresponded to caseous necrosis, whereas high signal intensity related to granulomas or effusion. Postcontrast T1-weighted images showed enhancement at the peripheries rather than the centers of tuberculous lesions. These results indicate that tuberculous arthritis should be included in the differential diagnosis when intra-articular lesions with low or intermediate signal intensity are found on T2-weighted images.     

MR imaging assessment of clinical problems in rheumatoid arthritis

Although MR imaging has been increasingly recognized as a useful tool in the diagnosis of early rheumatoid arthritis (RA) and in the assessment of disease activity, these applications have not yet been usually included in the routine management of this condition. Our goal is to review the current role of MRI in the everyday clinical management of patients with RA. The usefulness of MRI in the evaluation of articular and para-articular changes in specific locations, mainly the craniocervical region and the temporomandibular joint, are reviewed. Clinical problems derived from local extra-articular involvement, such as tenosynovitis, "rice-bodies" bursitis, and Baker's cyst rupture, are also described. Finally, we also review the value of MRI in evaluation of some complications of RA such as tendinous rupture, osteonecrosis, stress fracture, and septic arthritis/osteomyelitis.     

Functional MR Imaging of Psychogenic Amnesia: A Case Report

We present here a case in which functional MR imaging (fMRI) was done for a patient who developed retrograde psychogenic amnesia for a four year period of her life history after a severe stressful event. We performed the fMRI study for a face recognition task using stimulation with three kinds of face photographs: recognizable familiar faces, unrecognizable friends'' faces due to the psychogenic amnesia, and unfamiliar control faces. Different activation patterns between the recognizable faces and unrecognizable faces were found in the limbic area, and especially in the amygdala and hippocampus.     

腕关节动态MRI增强在早早期类风湿性关节炎诊断中的价值

目的 探讨动态增强MRI评估腕关节滑膜改变在早早期类风湿性关节炎中的诊断价值.方法 对ACR/EULAR评分小于6分的25例患者腕关节进行MR成像,动态随访观察滑膜的改变,分析腕关节滑膜MRI评分与类风湿性关节炎的相关性.结果 25例患者均进行了MRI检查,所有病例均进行了随访,对12例怀疑有滑膜改变的患者进行了增强检查,滑膜轻度增厚10例,2例未见明显强化.结论 MRI增强扫描在动态随访观察早早期类风湿性关节炎中具有较好的价值,为临床早期干预提供理论依据.     

Contrast-Enhanced MR Imaging of Lymph Nodes in Cancer Patients

The accurate identification and characterization of lymph nodes by modern imaging modalities has important therapeutic and prognostic significance for patients with newly diagnosed cancers. The presence of nodal metastases limits the therapeutic options, and it generally indicates a worse prognosis for the patients with nodal metastases. Yet anatomic imaging (CT and MR imaging) is of limited value for depicting small metastatic deposits in normal-sized nodes, and nodal size is a poor criterion when there is no extracapsular extension or focal nodal necrosis to rely on for diagnosing nodal metastases. Thus, there is a need for functional methods that can be reliably used to identify small metastases. Contrast-enhanced MR imaging of lymph nodes is a non-invasive method for the analysis of the lymphatic system after the interstitial or intravenous administration of contrast media. Moreover, some lymphotrophic contrast media have been developed and used for detecting lymph node metastases, and this detection is independent of the nodal size. This article will review the basic principles, the imaging protocols, the interpretation and the accuracies of contrast-enhanced MR imaging of lymph nodes in patients with malignancies, and we also focus on the recent issues cited in the literature. In addition, we discuss the results of several pre-clinical studies and animal studies that were conducted in our institution.     

Gadolinium-enhanced MR imaging of the wrist in rheumatoid arthritis: value of fat suppression pulse sequences

 Objective. To determine the usefulness of fat-suppressed gadolinium (Gd)-enhanced MR imaging of the wrist in patients with rheumatoid arthritis (RA). Design and patients. Fat-suppressed Gd-enhanced T1-weighted spin-echo (SE) images were obtained and compared with other standard techniques in 38 wrists of 27 patients (22–77 years) with RA. Scoring based on the degree of synovial enhancement of each joint was developed and the total scores (J-score) were correlated with radiographic stage, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and symptomatic change in the follow-up study. Results. Synovial proliferations showed marked enhancement in all the wrists. In addition, contrast enhancement in the bone marrow and tenosynovium was seen in 36 and eight wrists respectively. Fat-suppressed Gd-enhanced T1-weighted images demonstrated these abnormalities better than other techniques. The J-scores correlated well with values of CRP (P=0.0034), but not with radiographic stages and ESR. Conclusion. Fat-suppressed Gd-enhanced T1-weighted SE images can clearly demonstrate most of the essential lesions in RA including the proliferative synovium, bone erosion, bone marrow inflammatory change, and tenosynovitis. Scoring based on the extent of Gd-enhancement of synovium can be useful in the assessment of the inflammatory status.     

Time-resolved MR angiography of the upper abdomen: initial clinical experience

In this study, thirty-eight patients with a variety of upper abdominal diseases were examined with three-dimensional time-resolved MR angiography (7 sec/data set). Visualisation of arterial and venous anatomy was excellent in the majority of patients. Moreover, subtraction images could be calculated and organ perfusion could be assessed. It is concluded that this technique opens new perspectives for a comprehensive evaluation of vascular and parenchymal disease. Received: 14 April 1998; Revision received: 23 October 1998; Accepted: 9 November 1998     

MR imaging in the diagnosis and management of inheritable musculoskeletal disorders

Although the initial identification of a congenital skeletal malformation is usually made by a combination of clinical examination, conventional radiology and genetic tests, this review illustrates the additional value of magnetic resonance imaging (MRI) in the diagnosis, determination of the extent of the disease, demonstration of associated abnormalities, therapy planning, disease monitoring and prognosis evaluation.     

Minimizing contrast agent dose during intraarterial gadolinium-enhanced MR angiography: in vitro assessment.

PURPOSE: To minimize contrast agent dosage for intra-arterial (IA) contrast-enhanced magnetic resonance angiography (CE-MRA) by examining the effects of encoding order (elliptical vs. sequential) and injection duration (100% to 30% of the acquisition time). MATERIALS AND METHODS: Catheter-based IA gadolinium (Gd) injections were performed in an arterial flow phantom. Blood flow rates, injection rates, and injection durations were systematically varied. Signal-to-noise (SNR) measurements were obtained in the aorta, renal artery, and common iliac artery. RESULTS: No significant SNR losses were observed for any of the vessels with 75% injection duration, or for the aorta and iliac artery with 50% injection duration. Excellent images of all vessels were obtained at 50% injection duration. There was no significant SNR difference between encoding schemes. CONCLUSION: Contrast agent dosage can be substantially reduced without loss of SNR by limiting injection to part of the imaging acquisition time.     

Multidisciplinary Functional MR Imaging for Prostate Cancer

Various functional magnetic resonance (MR) imaging techniques are used for evaluating prostate cancer including diffusion-weighted imaging, dynamic contrast-enhanced MR imaging, and MR spectroscopy. These techniques provide unique information that is helpful to differentiate prostate cancer from non-cancerous tissue and have been proven to improve the diagnostic performance of MRI not only for cancer detection, but also for staging, post-treatment monitoring, and guiding prostate biopsies. However, each functional MR imaging technique also has inherent challenges. Therefore, in order to make accurate diagnoses, it is important to comprehensively understand their advantages and limitations, histologic background related with image findings, and their clinical relevance for evaluating prostate cancer. This article will review the basic principles and clinical significance of functional MR imaging for evaluating prostate cancer.     

Safety issues and updates under MR environments

Magnetic resonance (MR) imaging is a useful imaging tool with superior soft tissue contrast for diagnostic evaluation. The MR environments poses unique risks to patients and employees differently from ionizing radiation exposure originated from computed tomography and plain x-ray films. The technology associated with MR system has evolved continuously since its introduction in the late 1970s. MR systems have advanced with static magnetic fields, faster and stronger gradient magnetic fields and more powerful radiofrequency transmission coils. Higher field strengths of MR offers greater signal to noise capability and better spatial resolution, resulting in better visualization of anatomic detail, with a reduction in scan time. With the rapid evolution of technology associated with MR, we encounter new MR-related circumstances and unexpected dangerous conditions. A comprehensive update of our knowledge about MR safety is necessary to prevent MR-related accidents and to ensure safety for patients and staff associated with MR. This review presents an overview about MR-related safety issues and updates.     

腕关节MRI对关节炎诊断的临床价值

目的研究各种关节炎腕关节MRI表现，及其对关节炎的鉴别诊断的价值。方法搜集在风湿科曾有腕关节疼痛病史的门诊及住院患者151例，男45例，女106例。进行临床及双腕关节MR检查。151例中临床诊断类风湿性关节炎80例、未分化脊柱关节病29例、血清阴性脊柱关节病20例、其他结缔组织关节病22例。结果80例类风湿性关节炎均可见双侧血管翳表现，29例未分化脊柱关节病中3例可见双侧血管翳表现，24例可见单侧血管翳表现，20例血清阴性脊柱关节病中4例可见双侧血管翳表现，15例可见单侧血管翳表现；22例其它结缔组织关节病中21例可见单侧血管翳表现。MRI显示各种关节炎组单侧血管翳差异无统计学意义（X^2=6．157，P〉0．05）。各种关节炎组在双侧关节血管翳方面的差异有统计学意义（X^2=126．882，P〈0．001）。类风湿性关节炎与未分化脊柱关节病（x^2=94．192，P〈0．001）、类风湿性关节炎与血清阴性脊柱关节病（x^2=70．354，P〈0．001）、类风湿性关节炎与其他结缔组织关节病（x^2=96．174，P〈0．001）差异均有统计学意义。结论MRI在各种关节炎的鉴别诊断中具有重要价值。     

Optimizing fast spin echo acquisitions for hepatic imaging in normal subjects

The purpose of this study was to determine which implementations of a T2-weighted fast spin-echo sequence of the liver resulted in observer preference in normal subjects. Five volunteers were scanned with a series of fast spin-echo sequences modified to allow for flow compensation, respiratory triggering (RT), ECG triggering, randomized phase encoding (RPE), breathholding, and echo train length (ETL). Images were compared with conventional 2500/40/80 msec spin-echo images using flow compensation and spatial presaturation by two observers blinded to the specific sequence parameters. All FSE sequences were completed in less than the 12 minutes necessary to perform a conventional spin-echo sequence. The most preferred fast spin-echo sequence employed flow compensation, RT, and used an 8 ETL. Analysis of image preference, signal to noise, and contrast to noise showed that RT was the single most important variable in determining each image response (P < .01, P < .02, P < .01, respectively). There was some evidence that images obtained with an 8 ETL were preferred over those using a 16 ETL (P=.07). No other variables approached statistical significance although one reader preferred images with flow compensation in the frequency direction to those either not flow compensated or flow compensated in the slice direction. Respiratory triggered fast spin-echo images combined with flow compensation in the frequency direction and using ETL=8 can provide image quality equal to conventional spin-echo sequences with significant time savings.     

FLAIR imaging for multiple sclerosis: a comparative MR study at 1.5 and 3.0 Tesla

The purpose of this study was (1) to identify the optimal TE for FLAIR-imaging at 3.0 T assessing three different echo times qualitatively and quantitatively and (2) to evaluate the diagnostic efficacy of high-field 3.0-T FLAIR imaging in comparison to conventional 1.5-T MRI in patients with multiple sclerosis (MS). Twenty-two patients with clinically definite MS underwent axial FLAIR imaging at 1.5 and 3.0 T. In 15 of these patients further FLAIR images with a TE of 100, 120 and 140 ms were acquired at 3.0 T. Imaging protocols were modified for 3.0 T using the increased SNR to acquire more and thinner slices while maintaining a comparable scan time. FLAIR images of either different TEs or different field strengths were ranked for each patient qualitatively by two observers. Signal intensity measurements were obtained in the gray and white matter, CSF and representative white matter lesions (WML). At 3.0 T, a TE of 100 and 120 ms proved superior in all qualitative categories when compared to 140 ms. In the quantitative assessment CNR of WML was highest for 120 ms (CNR: 19.8), intermediate for 100 ms (17.2) and lowest for 140 ms (15.3) (P<0.003). For lesion conspicuity and overall image quality, 3.0 T was judged superior to 1.5 T, whereas no difference was found for gray-white differentiation and image noise. With regard to artifacts, 3.0 T was inferior to 1.5 T. The CNR for WML was slightly lower at 3.0 T, but the difference was not significant (22.6 vs. 28.0, P=ns). However, significantly more WML were detected at 3.0 T than at 1.5 T (483 vs. 341, P<0.0001). The optimal echo time for FLAIR imaging at 3.0 T is 120 ms due to the significantly higher CNR of WML. By trading the higher SNR at 3.0 T for better spatial resolution, nearly the same CNR level could be maintained, increasing lesion detectability at 3.0 T compared to 1.5 T. Thus, high-field MRI may further strengthen the role of MRI as the most sensitive paraclinical test for the early diagnosis of MS.     

MR Imaging Features of Obturator Internus Bursa of the Hip

The authors report two cases with distension of the obturator internus bursa identified on MR images, and describe the location and characteristic features of obturator internus bursitis; the "boomerang"-shaped fluid distension between the obturator internus tendon and the posterior grooved surface of the ischium.     

Time-resolved three-dimensional pulmonary MR angiography and perfusion imaging with ultrashort repetition time

RATIONALE AND OBJECTIVES: The purpose of this study was to implement ultrafast, multiphase three-dimensional (3D) magnetic resonance (MR) angiography and perfusion imaging after bolus injection of contrast medium to generate preliminary validation of parameters in a pig model and to illustrate potential applications in patients with lung abnormalities. MATERIALS AND METHODS: Five healthy volunteers, five patients, and three pigs underwent rapid, time-resolved pulmonary MR angiography and perfusion imaging on a 1.5-T MR imager. All patients had undergone correlative computed tomographic or conventional angiography. The pulse sequence was a 3D spin-warp, gradient-echo acquisition with a repetition time of 1.6 msec and an echo time of 0.6 msec. Each 3D acquisition lasted 2-3 seconds, and 8-16 sequential measurements were made in each study. Artificial pulmonary emboli were generated in pigs with gelatin sponge. All patients had diseases of the pulmonary circulation (as confirmed with other studies). RESULTS: Multiphasic, time-resolved pulmonary parenchymal enhancement was demonstrated in all healthy subjects and animals. All segmental (n = 100) and subsegmental (n = 200) branches were identified in the healthy subjects. Perfusion deficits were clearly demonstrated in all pigs after gelatin embolization. Perfusion defects were identified in two patients with lung disease. Abnormalities of the pulmonary vasculature were clearly identified in the patient group. CONCLUSION: Dynamic time-resolved 3D pulmonary MR angiography and perfusion imaging is feasible in humans as well as in animals. Induced perfusion deficits are identifiable after artificial embolization in pigs. Combined pulmonary MR angiography and parenchymal (perfusion) imaging may improve evaluation of the pulmonary circulation in a variety of conditions.