Comparison of 3.0-T MR vs 3.0-T MR arthrography of the hip for detection of acetabular labral tears and chondral defects in the same patient population

Objective:

We report our experience in diagnostic sensitivity of 3.0-T conventional MR vs 3.0-T MR arthrography of the hip for detection of acetabular labral tears and chondral defects in the same patient population.

Methods:

43 consecutive patients had both conventional hip MR and MR arthrography examinations performed. These examinations were reviewed retrospectively by independent reading of two musculoskeletal radiologists who read the MR and MR arthrogram examinations in a randomized fashion (i.e. MR and MR arthrogram examinations were read at separate sittings and in a randomized fashion so as not to bias reviewers). Scans were assessed for acetabular labral tears and chondral defects. All patients went on to arthroscopy.

Results:

Of these 43 patients, 40 had acetabular labral tears read by Reader 1 and 39 had acetabular labral tears read by Reader 2 on MR arthrogram, 39 had acetabular labral tears read by Reader 1 and 38 had acetabular labral tears read by Reader 2 on conventional MR examination. There were 42 labral tears in 43 patients at arthroscopy. There were four false-negative labral tears compared with arthroscopy on MR and three false negatives on MR arthrography for Reader 1 and five false negatives on MR and four false negatives on MR arthrography for Reader 2. Each reader had one false-positive labral tear compared with arthroscopy on both MR and MR arthrography. There were 32 acetabular chondral defects at arthroscopy. Reader 1 saw 21 acetabular chondral defects on conventional MR and 27 chondral defects at MR arthrography. Reader 2 saw 19 acetabular chondral defects at conventional MR and 25 acetabular chondral defects on MR arthrography. There were no false-positive readings of chondral defects compared with arthroscopy on MR and one false positive for Reader 1 and two false positives for Reader 2 on MR arthrography as compared with arthroscopy. On conventional MR examination, sensitivities and specificities as compared with arthroscopy were as follows: Reader 1 acetabular labral tear (90% sensitivity, 0% specificity) and Reader 2 acetabular labral tear (88% sensitivity, 0% sensitivity). On MR arthrogram, sensitivities and specificities as compared with arthroscopy for Reader 1 were 93%, 0% and for Reader 2 were 90%, 0%, respectively. Sensitivities and specificities for detection of acetabular chondral defects as compared with arthroscopy were Reader 1 conventional MR (65% sensitivity, 100% specificity), Reader 1 MR arthrography (81% sensitivity, 91% specificity), Reader 2 conventional MR (59% sensitivity, 100% specificity) and Reader 2 MR arthrography (71% sensitivity, 82% specificity).

Conclusion:

In this series, 3.0-T MR demonstrated sensitivity for detection of acetabular labral tears that rivals the sensitivity of 3.0-T MR arthrography of the hip. In this series, 3.0-T MR arthrography was more sensitive than conventional 3.0-T MR for detection of acetabular chondral defects.

Advances in knowledge:

3.0-T MR and MR arthrography are near equivalent in the diagnosis of acetabular labral tears. This information is useful for pre-operative planning.MR arthrography has been reported to be more sensitive and specific for detection of acetabular labral tears in the hip than conventional MRI.^1–10 MR arthrography has also been reported to be superior in detection of acetabular cartilage defects as compared with conventional MRI.¹¹ To our knowledge 3.0-T MR vs 3.0-T MR arthrography sensitivity for detection of acetabular labral tears and chondral defects has not been specifically assessed.To our knowledge, Petersilge et al¹ first reported the utility of hip MR arthrography in the diagnosis of acetabular labral tears. Toomayan et al² compared MR arthrography of the hip with conventional MRI of the hip in different patient populations. He found MR arthrography with a small field of view to be substantially more sensitive for detection of acetabular labral tears than conventional MRI. Sutter et al¹¹ found 1.5 T MR arthrography to be superior to conventional MRI for detecting labral tears and acetabular cartilage defects.Patients with acetabular labral tears present with symptoms of persistent pain, clicking, locking and decreased range of motion. With the availability of hip arthroscopy, labral tears can more easily be addressed with minimally invasive surgery. Accurate pre-operative identification of labral tears is needed.² Based on previous studies demonstrating the accuracy of MR arthrography in detection of acetabular labral tears, surgeons often request MR arthrography of the hip to characterize labral tears prior to surgery.^1–10 The purpose of this study is to assess 3.0-T MR vs MR arthrography diagnostic performance in detection of acetabular labral tears and chondral defects in the same patient population using arthroscopy as a reference standard.     

3.0T常规MRI与MR髋关节造影诊断髋臼唇撕裂的对比研究

目的 在3.0 T场强中,比较常规髋关节MRI及MR髋关节造影对髋臼唇撕裂的诊断价值.方法 回顾分析44例髋关节病变患者的患侧髋关节常规MRI及MR髋关节造影资料,将每例患者的臼唇划分为前、上、后3处区域(共计132处),确定有无撕裂,并进行分型.其中5例患者经髋关节镜检查.对于常规MRI及MR髋关节造影获得的臼唇撕裂及分型数据差异比较采用Wilcoxon秩和检验,一致性比较采用Kappa检验.结果 常规MRI与MR髋关节造影诊断完全相同者计116处臼唇,只有16处存在诊断差异.其中,前者诊断无撕裂而后者诊断撕裂者9处,前者诊断撕裂但后者诊断无撕裂者6处,其余1处两者均诊断为撕裂但分型不同.常规MRI与MR髋关节造影的评价差异没有统计学意义(Z=0.347,P＞0.05),且具有极好的一致性(K=0.781,P＜0.01).在接受关节镜的5例患者中,常规MRI、MR髋关节造影及关节镜结果均完全吻合.结论 对髋臼唇撕裂,3.0 T常规髋关节MRI可获得与MR髋关节造影基本相同的诊断效果.     

Triad of MR arthrographic findings in patients with cam-type femoroacetabular impingement

PURPOSE: To retrospectively analyze magnetic resonance (MR) arthrographic findings in patients with clinical cam-type femoroacetabular impingement. MATERIALS AND METHODS: This study was approved by the institutional review board, and informed consent was waived. Study was compliant with the Health Insurance Portability and Accountability Act. Forty-two MR arthrograms obtained in 40 patients with clinical femoroacetabular impingement were analyzed retrospectively by two radiologists. Quantitative analysis by using alpha angle measurement was performed to assess anterosuperior femoral head-neck morphology. Presence of labral tears, articular cartilage lesions, paralabral cysts, os acetabuli, and synovial herniation pits was recorded. Presence of the typical triad of anterosuperior labral tear, anterosuperior cartilage lesion, and abnormal alpha angle was recorded. Surgical comparison was available for 11 patients. RESULTS: At imaging, in 40 patients (22 male, 18 female) with a mean age of 36.5 years, 39 of 42 hips (93%) had an abnormal alpha angle, with a mean angle of 69.7 degrees ; 40 of 42 (95%) had an anterosuperior cartilage abnormality; and 42 of 42 (100%) had an anterosuperior labral tear. Thirty-seven of 42 hips (88%) had the triad. Six had paralabral cysts, 17 had an os acetabuli, and two had synovial herniation pits. Surgical comparison for 11 hips led to confirmation of all labral and cartilage abnormalities seen at imaging. CONCLUSION: MR arthrography demonstrated a triad of abnormal head-neck morphology, anterosuperior cartilage abnormality, and anterosuperior labral abnormality in 37 of 42 patients with cam-type femoroacetabular impingement.     

MR imaging and MR arthrography of paraglenoid labral cysts

OBJECTIVE: We investigated the pathophysiology of paraglenoid labral cysts on the basis of MR imaging, MR arthrography, and cyst aspiration. MATERIALS AND METHODS: From 2211 MR imaging examinations, 51 (2.3%) cysts in 46 patients were identified. MR arthrography (n = 5), cystography (n = 1), arthroscopy (n = 17), percutaneous needle aspiration (n = 4), and medical records were also reviewed (n = 46). RESULTS: On MR imaging and arthrography, cysts were best viewed on T2-weighted images. Mean cyst diameter and volume were 2.2 cm and 2.8 cm3, respectively. Fifty-seven percent of cysts were located adjacent to the posterior labrum. On MR imaging and arthroscopy, a labral tear was identified in 27 (53%) and 15 (88%) patients, respectively. Eight cysts that caused compression neuropathy were large (mean size, 3.1 cm; p = 0.04) and located next to the posterior or inferior labrum. In four of five patients, MR arthrograms showed no intraarticular contrast material in the cyst. Cystograms showed no communication with the glenohumeral joint space, and cyst aspiration resulted in temporary symptom relief; however, cysts recurred in three of four patients. CONCLUSION: Most paralabral cysts are associated with labral tears. Paralabral cysts may be difficult to identify on MR arthrography unless a T2-weighted sequence is performed. Direct communication between a cyst and joint space rarely occurs. A posterior or inferior cyst may cause compression neuropathy of the suprascapular or axillary nerve, respectively. Cyst aspiration may result in temporary relief of symptoms, but an untreated labral tear should be suspected if cysts recur.     

Acute and subacute ischemic stroke at high-field-strength (3.0-T) diffusion-weighted MR imaging: intraindividual comparative study

PURPOSE: To compare signal-to-noise ratios (SNRs), contrast-to-noise ratios (CNRs), image quality, and confidence in diagnosis between 1.5- and 3.0-T diffusion-weighted (DW) magnetic resonance (MR) imaging of ischemic stroke lesions. MATERIALS AND METHODS: The study design was approved by the institutional review board, and all patients gave informed consent. In a prospective intraindividual study, 25 patients who had clinical symptoms consistent with ischemic stroke underwent DW MR imaging at both 1.5 T and 3.0 T. The 3.0- or 1.5-T examination was performed immediately one after the other, in random order. Two readers in consensus recorded the presence and number of ischemic lesions and rated image quality and lesion conspicuity. The image SNR and the CNR of the ischemic lesions were quantified. Paired Student t and Wilcoxon matched-pairs signed rank tests were used to test for statistical significance. RESULTS: Image quality at 3.0-T DW MR imaging was consistently lower than that at 1.5-T DW MR imaging owing to greater image distortions (P < .05). Yet, overall SNR and lesion CNR at 3.0 T increased significantly; mean increases were 48.8% (P < .001) and 96.3% (P < .01), respectively. The higher overall SNR and lesion CNR translated into a significantly higher sensitivity in the detection of ischemic lesions at 3.0 T than at 1.5 T. Of the total of 48 lesions that were identified in 19 of the 25 patients, 47 (98%) were diagnosed at 3.0 T and 36 (75%) were diagnosed at 1.5 T. In addition, the conspicuity of the lesions that were visible with both systems was significantly higher at 3.0 T (P < .001). CONCLUSION: Although 3.0-T DW MR imaging generates greater image distortions, it yields increased SNR and CNR compared with DW MR imaging at 1.5 T. The increased CNR at 3.0 T translates into a significantly improved diagnostic confidence in the detection of focal apparent diffusion coefficient changes in the setting of subacute and acute ischemic stroke.     

MR arthrography of the shoulder: comparison with conventional MR imaging

Twenty-three patients underwent both conventional MR imaging of the shoulder and MR shoulder arthrography for clinically suspected labral or rotator cuff abnormalities. Images obtained before and after contrast administration were studied independently, and without knowledge of clinical findings, by two radiologists for the presence of abnormalities of the glenoid labrum or rotator cuff. Results were correlated with surgical findings in all patients. Nine patients had surgically proved labral tears. MR arthrography detected all nine labral abnormalities, while six of the nine were missed on conventional MR imaging. Fourteen patients had surgically proved rotator cuff tears. MR arthrography detected 11 of the 14 tears and missed three partial tears on the bursal surface. Conventional MR imaging detected nine cuff tears and missed five tears; two of these were complete rotator cuff tears and three were partial tears of the undersurface of the rotator cuff. Our results suggest that MR arthrography enhances the accuracy of MR in the evaluation of the glenoid labrum and rotator cuff tendon.     

MR Arthrography of the Hip

Magnetic resonance imaging (MRI) of the hip has been valuable in the diagnosis of occult osseous abnormalities and of periarticular soft tissue disorders. MRI has been less useful in the evaluation of acetabular labral tears and other intra-articular abnormalities. Image optimization is more technically challenging in the hip than in smaller joints because the overlying soft tissues are thicker, resulting in decreased spatial and contrast resolutions that may not be adequate to distinguish the acetabular labrum from subchondral bone, articular cartilage, and joint capsule. MR arthrography (MRA) extends the capabilities of conventional MRI because contrast solution separates intra-articular structures and outlines abnormalities. In hips with suspected acetabular labral injury, arthrographic MR images demonstrate the location and length of tears and the presence of associated capsular defects. Arthrographic MR images may also enable the accurate diagnosis of cartilage lesions and intra-articular loose bodies. This article illustrates normal arthrographic MR features of the hip as well as pathologic disorders of the acetabular labrum, capsule, and articular cartilage     

Comparison of 3.0- and 1.5-T three-dimensional time-of-flight MR angiography in moyamoya disease: preliminary experience

PURPOSE: To prospectively compare 3.0- and 1.5-T three-dimensional (3D) time-of-flight (TOF) magnetic resonance (MR) angiography in patients with moyamoya disease, with special emphasis on the visualization of abnormal netlike vessels (moyamoya vessels). MATERIALS AND METHODS: Study protocols were approved by the local ethics committee; written informed consent was obtained from all patients. The study included 24 consecutive patients with moyamoya disease (four male and 20 female patients). Patients ranged in age from 17 to 66 years (mean age, 41 years). Moyamoya disease had been diagnosed in all patients before they were entered into the study. All patients underwent 3D TOF MR angiography at both 3.0 and 1.5 T; imaging examinations were performed within 14 days of each other. Maximum intensity projections (MIPs) obtained with MR angiography performed at both 3.0 and 1.5 T were evaluated by two neuroradiologists; the visualization of moyamoya vessels was graded according to a 4-point scale. For both 3.0- and 1.5-T imaging, the number of high-signal-intensity areas and the summation of cross-sectional areas of high signal intensity on source images obtained at the same level of MR angiography were compared quantitatively by using the Wilcoxon matched-pair signed-rank test. RESULTS: Moyamoya vessels were better visualized on MIPs obtained with 3.0-T imaging than on MIPs obtained with 1.5-T imaging (P < .001). At the identical level of the source image, 3.0-T imaging depicted more high-signal-intensity areas than did 1.5-T imaging. Wider cross-sectional areas of moyamoya vessels were visualized with 3.0-T imaging than with 1.5-T imaging (P < .001). CONCLUSION: Moyamoya vessels are better depicted with MR angiography at 3.0 T than at 1.5 T.     

Superior labral anteroposterior lesions: MR arthrography with arm traction.

OBJECTIVE: The purpose of this study was to investigate the efficacy of arm traction combined with MR arthrography in the evaluation of superior labral anteroposterior (SLAP) lesions. MATERIALS AND METHODS: Cadaveric shoulders were studied with a 1.5-T MR imaging unit with the arm externally rotated. Fifteen milliliters of a gadolinium-containing contrast agent were injected into the glenohumeral joint. Twenty-four sets of images of cadaveric joints were evaluated independently by two observers. These sets consisted of MR arthrographic images obtained with traction (applied to the wrist using 1- to 3-kg weights) and without traction in five shoulders in which SLAP lesions had been excluded arthroscopically or by cadaveric sectioning; and MR arthrographic images obtained with and without traction in seven shoulders in which various types of SLAP lesions had been created arthroscopically and later confirmed by cadaveric sectioning. RESULTS: Analysis of the data indicated that MR arthrography in combination with arm traction and external rotation improved diagnostic accuracy with regard to identification and categorization of SLAP lesions when compared with studies made without traction. CONCLUSION: The combination of MR arthrography and arm traction with the shoulder in external rotation provides a more effective approach for detection of SLAP lesions than does similar MR arthrography performed without arm traction.     

Time-of-flight MR angiography: comparison of 3.0-T imaging and 1.5-T imaging--initial experience

Intracranial three-dimensional time-of-flight (TOF) magnetic resonance (MR) angiography was performed in seven healthy volunteers and eight patients with both 1.5-T and 3.0-T MR systems with standard and high spatial resolutions (true voxel sizes, 0.48 x 0.75 x 2.00 mm and 0.30 x 0.44 x 1.00 mm, respectively). Superior image quality and significantly better depiction of small vessel segments and vascular disease were observed at high-spatial-resolution 3.0-T TOF MR angiography but not at standard 1.5-T or standard 3.0-T TOF MR angiography (P <.01, respectively). Intracranial high-spatial-resolution TOF MR angiography at 3.0-T imaging provides diagnostic improvement in studies of cerebrovascular disease.     

Articular cartilage and labral lesions of the glenohumeral joint: diagnostic performance of 3D water-excitation true FISP MR arthrography

Objective  

To evaluate the diagnostic performance of MR arthrography in the detection of articular cartilage and labral lesions of the glenohumeral joint using a transverse 3D water-excitation true fast imaging with steady-state precession (FISP) sequence.     

Articular cartilage defects: detectability in cadaver knees with MR

The capability of 1.5-T MR imaging to detect focal defects in articular cartilage was investigated with cadaveric knees with and without intraarticular injection of saline and gadolinium-DTPA (Gd-DTPA). Full-thickness cartilage lesions ranging in diameter from 1 to 5 mm were surgically created in the femoral articular surfaces. Images were acquired with a variety of pulse techniques, slice thicknesses, and interslice gaps as well as one or two signal excitations. Potential intraarticular contrast agents (saline and Gd-DTPA) were tested, and their signal behaviors compared with that of hyaline cartilage. All cartilage defects were occult on T1-weighted and balanced images without Gd-DTPA. The smallest defect identified by using intraarticular saline was 3 mm in diameter and was apparent only on T2-weighted images. Intraarticular Gd-DTPA afforded detection of defects as small as 2 mm, even with short imaging times. Signal-intensity differences between saline and articular cartilage were minimal on T1-weighted images and increased on T2-weighted images; intensity differences were high between Gd-DTPA and articular cartilage on all imaging sequences. These results indicate that intraarticular fluid and appropriate selection of imaging sequences are necessary for delineation of focal defects in articular cartilage. They also show that Gd-DTPA is the optimal contrast agent for this purpose.     

Can isotropic fast gradient echo imaging be substituted for conventional T1 weighted sequences in shoulder MR arthrography at 3 Tesla?

PURPOSE: To assess the practical utility of isotropic shoulder imaging in patients undergoing MR arthrography. Isotropic shoulder imaging can be performed in less than three minutes with use of fast gradients. MATERIALS AND METHODS: Two experienced musculoskeletal radiologists retrospectively interpreted MR images of the shoulder in 100 consecutive patients undergoing MR arthrography of the shoulder. All patients underwent MRI of the shoulder in oblique coronal, oblique sagittal, and axial planes on a 3.0-Tesla MRI system. All patients had conventional fast spin-echo T1-weighted imaging. All patients also had thin section (0.4 mm) isotropic spoiled gradient echo images performed. A total of 67 of the 100 patients underwent subsequent arthroscopy and results were compared with MR interpretations. RESULTS: There were 41 full-thickness supraspinatus tendon tears, nine partial-thickness supraspinatus tendon tears (seven articular surface and two bursal surface), 21 superior labral, 18 anterior labral, and seven posterior labral tears demonstrated by consensus retrospective reading of the 100 shoulder MR exams. There was no difference in interpretation of the isotropic images as compared to the conventionally acquired images in the oblique coronal, oblique sagittal, and axial planes. Some patients had more than one finding on each exam. A total of 67 patients went on to arthroscopy. There were 41 full-thickness supraspinatus tendon tears, nine partial-thickness supraspinatus tendon tears, 21 superior labral, 18 anterior labral, and seven posterior labral tears demonstrated on arthroscopy. All full- and partial-thickness supraspinatus tendon tears seen at arthroscopy were seen on consensus MR reading. A total of 19 out of the 21 patients with superior labral anterior posterior (SLAP) tears at arthroscopy were seen on consensus MR reading. A total of 16 of the 18 anterior labral tears and six of the seven posterior labral tears seen at arthroscopy were seen on consensus MR reading. Some of the 67 patients had more than one finding on arthroscopy. CONCLUSION: Isotropic imaging of the shoulder is practical in clinical imaging when performed with use of fast gradients on a 3-Tesla system. Isotropic imaging provides the same clinical information as conventional imaging and can be acquired in less than three minutes.     

Cartilage lesions in the hip: diagnostic effectiveness of MR arthrography

PURPOSE: To evaluate the diagnostic performance of magnetic resonance (MR) arthrography in the detection of articular cartilage lesions in patients suspected of having femoroacetabular impingement and/or labral abnormalities. MATERIALS AND METHODS: Forty-two MR arthrograms obtained in 40 patients with a clinical diagnosis of femoroacetabular impingement and/or labral defect were retrospectively analyzed. Two readers independently interpreted the images for cartilage lesion location, depiction, and characteristics. Within 6 months after MR arthrography, each patient underwent open hip surgery, during which the entire cartilage of the hip joint was inspected. Sensitivity, specificity, accuracy, and positive and negative predictive values were calculated. kappa values were calculated to quantify the level of interobserver agreement. RESULTS: At surgery, most (37 [88%] of 42) cartilage defects were identified in the anterosuperior part of the acetabulum. In 23 (55%), 12 (29%), 10 (24%), and 10 (24%) hips, lesions were found in the posterosuperior acetabulum, anteroinferior acetabulum, posteroinferior acetabulum, and femoral head, respectively. The sensitivities and specificities of MR arthrographic detection of cartilage damage in all regions combined were 79% (73 of 92 regions) and 77% (91 of 118 regions), respectively, for reader 1 and 50% (46 of 92 regions) and 84% (99 of 118 regions), respectively, for reader 2. At interobserver comparison, agreement was fair (kappa = 0.31) for detection of cartilage lesions in the femoral head and poor (kappa 相似文献   

Improved image quality of intracranial aneurysms: 3.0-T versus 1.5-T time-of-flight MR angiography

BACKGROUND AND PURPOSE: We hypothesize that the nearly doubling of signal-to-noise ratio at 3.0 T compared with that at 1.5 T yields improved clinical MR angiograms and enables superior visualization of intracranial aneurysms. The goal of this study was to determine whether 3.0-T time-of-flight (TOF) MR angiography is superior to 1.5-T TOF MR angiography in the detection and characterization of intracranial aneurysms. METHODS: Fifty consecutive patients referred for MR angiography of a known or suspected intracranial aneurysm underwent 3-T TOF MR angiography. Seventeen of these 50 patients had also previously undergone 1.5-T TOF MR angiography and these images were used as a basis for comparison with images obtained at 3.0 T. Fourteen of 23 patients in whom aneurysms were identified also underwent prior conventional angiography, which was used as the reference standard. Readers blinded to patient history identified the presence and location of aneurysm(s) on angiograms and graded images for overall image quality by using a five-point scale. RESULTS: Twenty-eight aneurysms were identified in 23 of 50 patients. Seventeen aneurysms in 17 patients had been documented with 1.5-T MR angiography. The 3.0-T technique had a higher mean image quality score than that of the 1.5-T MR technique (P <.0001). Both 3.0-T and 1.5-T TOF MR angiography depicted all the aneurysms that had been documented by conventional angiography. CONCLUSION: 3D TOF MR angiography at 3 T offers superior depiction of intracranial aneurysms compared with that of 1.5-T TOF MR angiography.     

Comparison of multislice CT arthrography and MR arthrography for the detection of articular cartilage lesions of the elbow

The objective of this study was to compare the value of multislice CT arthrography and MR arthrography in the assessment of cartilage lesions of the elbow joint. Twenty-six cadaveric elbow specimens were examined with the use of CT arthrography and MR arthrography prior to joint exploration and macroscopic inspection of articular cartilage. Findings at CT and MR arthrography were compared with macroscopic assessments in 104 cartilage areas. At macroscopic inspection, 45 cartilage lesions (six grade 2 lesions, 25 grade 3 lesions, 14 grade 4 lesions) and 59 areas of normal articular cartilage were observed. With macroscopic assessment as the gold standard CT and MR arthrography showed an overall sensitivity/specificity of 80/93% and 78/95% for the detection of cartilage lesions, respectively. Only two of six grade 2 lesions were detected by CT and MR arthrography. For the diagnosis of grade 3 and 4 lesions, the sensitivity/specificity was 87/94% with CT arthrography, and 85/95% with MR arthrography. In an experimental setting multislice CT arthrography and MR arthrography showed a similar performance in the detection of cartilage lesions. Both methods indicated limited value in the diagnosis of grade 2 articular cartilage lesions.     

Assessment of knee cartilage in cadavers with dual-detector spiral CT arthrography and MR imaging

PURPOSE: To assess dual-detector spiral CT arthrography in the evaluation of the entire knee cartilage obtained from cadavers. MATERIALS AND METHODS: Two independent observers characterized articular cartilage in 12 cadaver knees in which MR imaging and dual-detector spiral CT arthrography were performed and compared their findings to those found during macroscopic assessment. The sensitivity and specificity of MR imaging and spiral CT arthrography for detecting grade 2A or higher and grade 2B or higher cartilage lesions, the Spearman correlation coefficient between arthrographic and macroscopic grading, and kappa statistics for assessing interobserver reproducibility were determined. RESULTS: At spiral CT arthrography, sensitivities and specificities ranged between 80% and 88% for the detection of grade 2A or higher cartilage lesions and ranged between 85% and 94% for the detection of grade 2B or higher cartilage lesions. At MR imaging, sensitivities and specificities ranged between 78% and 86% and between 76% and 91% for the detection of grade 2A or higher and grade 2B or higher cartilage lesions, respectively. Spearman correlation coefficients between spiral CT arthrography or MR imaging and macroscopic grading of articular surfaces were 0.797 and 0.702, respectively. CONCLUSION: Dual-detector spiral CT arthrography of the knee is a valuable method for the assessment of open cartilage lesions of the entire knee.     

Volumetric cartilage measurements of porcine knee at 1.5-T and 3.0-T MR imaging: evaluation of precision and accuracy

PURPOSE: To compare the precision and accuracy of 3.0-T and 1.5-T magnetic resonance (MR) imaging in the quantification of cartilage volume by using direct volumetric measurements as a reference standard. MATERIALS AND METHODS: The local animal experimentation committee did not require its approval for this study. Porcine knees were obtained from an abattoir. These specimens were used to optimize imaging parameters regarding effective signal-to-noise ratio (SNRE) and contrast-to-noise ratio (CNRE) for a fat-saturated spoiled gradient-recalled acquisition in the steady state (SPGR) sequence, a water excitation SPGR sequence, and a fast spin-echo sequence at 3.0 T and a fat-saturated SPGR sequence at 1.5 T. By using the optimized sequences, 18 specimens were imaged in less than 6 minutes per sequence. A fivefold repetition of measurements of four specimens was performed for precision analysis. Cartilage was segmented by using semiautomatic software to calculate the volume. After imaging, the cartilage was scraped off and the volume was measured directly by using a saline-displacement method to calculate accuracy. Precision and accuracy errors were calculated as the root-mean-squares of the single errors per specimen. RESULTS: SNRE and CNRE values, respectively, were highest for the water excitation sequence at 3.0 T (1.81 sec(-1/2) and 1.27 sec(-1/2)), followed by the fat-saturated SPGR sequence (1.52 sec(-1/2) and 1.07 sec(-1/2)). The fast spin-echo sequence and the fat-saturated SPGR sequence at 1.5 T had lower SNR(E) (1.27 sec(-1/2) and 0.59 sec(-1/2), respectively). Accuracy error for MR-based volume calculation at the femur was 5.0%, 3.0%, 21%, and 16% for the water excitation, fat-saturated SPGR, and fast spin-echo sequences at 3.0 T and the fat-saturated SPGR sequence at 1.5 T, respectively. CONCLUSION: MR imaging at 3.0 T was shown in our study to better quantify cartilage volume. SNRE and CNRE were substantially improved, resulting in significantly higher accuracy in determining cartilage volume.     

MR arthrography of the hip joint

MR arthrography of the hip joint is usually performed after a conventional MRI has been obtained to rule out other pathologies of the hip joint as for instance bone marrow edema or osteonecrosis of the hip. MR arthrography is mainly performed as a very special investigation, and it is executed in most cases if the clinician asks for the diagnosis of a labral lesion. In very rare cases, MR arthrography of the hip is performed to image cartilage disease or osteochondrosis dissecans or free intraarticular bodies. In this paper, the indications, the technique, and the most important pathology of the hip joint--labral lesions--will be described as well as variants of the normal acetabular labrum. After a conventional MRI of the hip joint has been performed, a MR arthrography of the hip will be obtained to search for labral pathology or cartilage disease. MR arthrography is obtained after the intraarticular injection of 10-20 ml of a 0.1 mmol solution of gadopentate-dimeglumine has been performed. The intraarticular injection can either be fluoroscopic-guided or CT-guided or directly MR-guided. After the intraarticular injection, MR arthrography will be performed by the use of paracoronal and parasagittal T1-weighted spin echo or gradient echo sequences. In cases of labral lesions (degeneration, labral tear, labral detachment) or cartilage disease MR arthrography proved to be more sensitive as conventional MRI as shown in the literature. The sensitivity of MRI to detect labral pathology was reported to be about 65%, and that of MR arthrography was reported to be about 92-95% compared to surgical results. According to the current literature, MR arthrography is the most sensitive method to delineate these kind of pathologies. Therefore, the invasive technique of MR arthrography may be justified for the correct diagnosis of these kind of pathologies after other pathologic entities have been ruled out by conventional MRI.     

MR imaging of cartilage in cadaveric wrists: comparison between imaging at 1.5 and 3.0 T and gross pathologic inspection

PURPOSE: To evaluate prospectively the diagnostic accuracy of magnetic resonance (MR) imaging in the identification of cartilage abnormalities at 3.0 and 1.5 T in cadaveric wrists, with gross pathologic findings as the standard of reference. MATERIALS AND METHODS: The study was approved by the hospital review board, and informed consent for scientific use of body parts had been provided by the subjects. Ten cadaveric wrists from nine subjects were evaluated (seven left wrists, three right; five women, four men; age range, 46-99 years; mean age, 80 years). All wrists were examined with MR imaging in a 1.5-T unit and a 3.0-T unit, with the same imaging protocol used with both systems. Imaging protocol included intermediate-weighted fast spin-echo sequences and three-dimensional gradient-recalled-echo sequences. Cartilage surfaces of the proximal and distal carpal row, including the scaphotrapeziotrapezoidal joint, were analyzed in blinded fashion by two musculoskeletal radiologists working independently and then in consensus. Open inspection of the wrists was used as the standard of reference. Sensitivity, specificity, accuracy, and positive and negative predictive values were calculated. The McNemar test was used to assess differences in diagnostic assessment. Weighted kappa values were calculated for interobserver agreement. RESULTS: One hundred seventy cartilage surfaces were graded. The sensitivity and specificity for cartilage lesions were 43%-52% and 82%-89%, respectively, at 1.5 T and 48%-52% and 82% at 3.0 T. Differences in assessment did not reach statistical significance (P > .99). Highest sensitivities were found in the proximal carpal row (67%-71%); lowest sensitivities were found in the distal carpal row (14%-24%). Interobserver agreement was higher for imaging at 3.0 T (kappa = 0.634) than at 1.5 T (kappa = 0.267). CONCLUSION: The performance of MR imaging for the detection of articular cartilage abnormalities in the wrist depends on anatomic location. Interobserver agreement is higher for imaging at 3.0 than at 1.5 T, but diagnostic performances were not significantly different (P > .99) at either field strength.