MRI evidence of high signal intensity and temporomandibular arthralgia and relating pain. Does the high signal correlate to the pain?

In order to investigate the relationship between various temporomandibular joint (TMJ) pain levels and the detection of high signal intensity (joint effusion) on T2 weighted magnetic resonance imaging (MRI), 19 consecutive patients who complained of unilateral painful TMJ hypomobility (closed locking) were involved in this study. All patients were clinically examined in a routine manner, and all patients rated their pain levels by a visual analogue scale and eight pain questionnaire prior MRI study. T1 and T2 weighted MRI was taken in sagittal section at unilateral affected joint side. The presence or absence of a high signal intensity spot within the TMJ compartment were judged by three examiners. The high signal intensity was detected in 10 joints, but not in 9 joints. In between these two groups, the pain ratio was calculated and compared. The data showed that there was no significant statistical correlation between pain levels and the presence of high signals. This study disclosed that the MRI detection of high signal intensity in the closed locking TMJ did not directly relate to the presence of TMJ pain nor the increased pain level. These indicate the need of further larger studies.

Extrasynovial spaces of the cruciate ligaments: anatomy, MR imaging, and diagnostic implications

OBJECTIVE

The purpose of our study was to define the anatomy of the extrasynovial space that cruciate ligaments occupy by examining the pattern on MR imaging of normal fluid distribution in the joints around the cruciate ligaments and correlating this distribution with histologic analysis of synovial reflections around the cruciate ligaments.

MATERIALS AND METHODS

MR images of five cadaveric knees were obtained serially after larger and larger amounts of contrast material were injected into the joint space. The patterns of fluid distribution around cruciate ligaments were noted. In two other cadaveric knees, the synovial sheath around the anterior cruciate ligament was injected directly with contrast material under CT guidance. Anatomic and histologic correlation was made with findings on corresponding MR images.

RESULTS

The pattern of fluid distribution is bounded by the synovial reflections around cruciate ligaments. When maximum joint distention is achieved, fluid almost surrounds the cruciate ligaments. The area without fluid is a triangular space between the anterior and posterior cruciate ligaments that appears on the midsagittal image. This triangular space of the cruciate ligaments is an extrasynovial space within which both the anterior cruciate ligament and the posterior cruciate ligament reside.

CONCLUSION

The overlying synovial membrane of the cruciate ligaments does not normally allow joint fluid to enter the substance of the ligaments or the triangular space of the cruciate ligaments. Therefore, fluid collections seen on MR imaging in these extrasynovial spaces or structures likely arises from injury to the cruciate ligaments.

Infectious arthritis: tailoring initial treatment to clinical findings

Infectious arthritis causes substantial morbidity and mortality. In patients with monoarticular involvement, careful history taking and attention to the clinical presentation aid in timely diagnosis. Certain factors (eg, patient age, structural changes in the joint, presence of chronic disease) provide clues to the likely infectious agent. Antibiotic treatment should be instituted immediately after culture specimens are obtained, and the choice of agent can be modified when antibiotic sensitivities are known. Surgical intervention may be necessary if medical therapy fails. An aggressive approach to evaluation and treatment is warranted when polyarticular infection is suspected.

Bilateral synovial coracoclavicular joints: MRI demonstration

Bilateral coracoclavicular joints, an anatomical variation, are described by radiography and MRI. MRI enabled precise identification of the nature of these joints. They were true synovial joints with cartilage and synovial fluid. To the best of the authors' knowledge, this is the first demonstration of such joints by MRI.

Optimization of a dual echo in the steady state (DESS) free-precession sequence for imaging cartilage

Three-dimensional (3D) MR imaging of the knee is useful to detect cartilage abnormalities, although the tissue contrast in 3D gradient-recalled echo (GRE) sequences such as gradient-recalled acquisition in the steady state (GRASS) or fast low-angle shot (FLASH) is poor. T2 contrast can be added to a GRASS sequence by combining the signals from the first and second gradient echoes, which form immediately after and immediately before each radio frequency (RF) pulse in a 3D GRE sequence. We have optimized a 3D dual echo in the steady state (DESS) sequence, which produces one averaged image from the two echoes, for use in the detection of articular cartilage abnormalities. In the optimization process, we examined the imaging parameters of flip angle (alpha), repetition time (TR), echo time (TE), and bandwidth to maximize the contrast between cartilage and joint fluid. A theoretical simulation of the sequence was confirmed with experiments conducted on phantoms with known T1 and T2. On the basis of theoretical predictions and experiments using healthy volunteers, we determined that an optimized sequence with a bandwidth of 98 Hz per pixel, TR of 30 msec, a TE of 7.1 msec, and an alpha of 60 degrees produced the highest contrast between cartilage and fluid within a defined acquisition time of 6 minutes. Additional contrast was obtained by filtering the second-echo image to eliminate noise before adding it to the first-echo image.

Repair and function of synovium after arthroscopic synovectomy of the dorsal compartment of the equine antebrachiocarpal joint

The reparative ability of equine synovium was determined by gross, histological, and ultrastructural examination. The functional potential of the synovium was estimated by examination of synovial cell organelles with transmission electron microscopy. Results from rested and exercised horses were compared to determine the effect of exercise on synovial healing. The response of synovectomized joint to exercise was evaluated with a standardized lameness examination and by gross, histological, and histochemical observations of the articular cartilage. A 7-mm diameter motorized synovial resector was used to perform a subtotal synovectomy in 1 antebrachiocarpal joint of each of 8 horses; the contralateral joint served as a control. After 2 months rest, four randomly selected horses were rigorously exercised for the remainder of the study; the other four horses continued paddock rest. Lameness examinations and synovial fluid analyses were conducted at 0, 2, 30, 60, and 120 days. Synovium and articular cartilage from all horses were examined at necropsy at 120 days. None of the horses were lame during the study, and transient synovitis occurred in the synovectomized joints. The hyaluronan concentration of treated joints decreased at 2 days but returned to normal by 60 days. Synovial fluid composition, including hyaluronan concentration, was unchanged by exercise. Significant cartilage damage was not observed in any of the joints. At 120 days, the healing synovium was devoid of villi and its subintima was fibrotic, however transmission electron microscopy confirmed that an intimal layer was present within the repair tissue. The cells within the repair tissue appeared actively engaged in both synthesis and phagocytosis. Exercise did not modify any of these findings. The results of this study suggest that 120 days after subtotal synovectomy, the joint environment was maintained and and the resected synovium had evidence of restoration and increased metabolic potential. Synovectomized joints withstood exercise but synovial repair was not accelerated by exercise.

Fluid-fluid levels in injured knees: do they always represent lipohemarthrosis?

PURPOSE

To determine if fluid-fluid levels on horizontal-beam radiographs of posttraumatic knee joints always represent lipohemarthrosis.

MATERIALS AND METHODS

The files of 41 patients with tibial plateau fracture were reviewed retrospectively. Twelve with fluid-fluid levels on radiographs who underwent computed tomography (CT) or magnetic resonance (MR) imaging were selected; CT attenuation and MR signal intensity patterns were used to assess fluid-fluid levels. Simulated hemarthrosis and lipohemarthrosis underwent plain radiography, CT, and MR imaging.

RESULTS

Eight patients showed no evidence of fat in the supernatant fluid with either CT (n = 7) or CT and MR imaging (n = 1). Fluid levels resulted from blood separating into cellular elements and supernatant serum. Four patients showed evidence of lipohemarthrosis with either CT (n = 3) or MR imaging (n = 1); in one of these patients, a double fluid-fluid level could be demonstrated retrospectively on plain radiographs.

CONCLUSION

Single fluid-fluid levels in posttraumatic knee joints do not necessarily represent a lipohemarthrosis. Double fluid-fluid levels are a more specific finding.

Magnetic resonance imaging of the temporomandibular joint: value of pseudodynamic images

Magnetic resonance fast scanning technique (gradient recalled acquisition at steady state) has been reported to be useful when evaluating the dynamics of the temporomandibular joint and also to be accurate for determining the disk position. Yet in our clinical experience gradient recalled acquisition at steady state images have frequently been inferior to proton density images for diagnosis of temporomandibular joint internal derangement. The first aim of this study was to compare gradient recalled acquisition at steady state images with proton density images for diagnosis of disk position. The second aim was to identify what additional information could be gathered from gradient recalled acquisition at steady state images when compared with static proton density images. We obtained unilateral images from 20 patients with signs and symptoms of temporomandibular joint internal derangement and from 20 asymptomatic volunteers. Multiple gradient recalled acquisition at steady state images were obtained during mouth opening and closing and proton density images were obtained at the closed and open mouth positions. The results showed that the gradient recalled acquisition at steady state images were in accordance with the proton density images in 32 joints (80%) and were false negative in 8 joints (20%). Six of the joints with false-negative gradient recalled acquisition at steady state images showed sideways disk displacement, and two showed partial anterior disk displacement. Gradient recalled acquisition at steady state images, on the other hand, provided information about movement pattern and also demonstrated impingement of the joint structures on the muscles anterior to the joint at maximal mouth opening. It was concluded that gradient recalled acquisition at steady state images cannot replace proton density images for diagnosis of disk position but they can provide supplementary information for evaluation of joint function.

Acute dislocation of the patella. A correlative pathoanatomic study

The objective of our study was to elucidate the characteristic pathoanatomy associated with patellar dislocation and report the preliminary results of early surgical repair. Twenty-three patients with documented patellar dislocation had standard radiographs and a magnetic resonance imaging scan. Intraarticular lesions were evaluated and treated arthroscopically followed by an open exploration of the medial aspect of the knee in 16 patients. Twelve patients were observed for a minimum of 2 years after surgical repair (average, 34 months). Eleven patients returned for a follow-up examination. Magnetic resonance imaging revealed effusion (100%), tears of the femoral insertion of the medial patellofemoral ligament (87%), increased signal in the vastus medialis muscle (78%), and lateral femoral condyle (87%) and medial patellar (30%) bone bruises. Arthroscopic examination revealed osteochondral lesions involving the patella and the lateral femoral condyle in 68% of cases. Open surgical exploration revealed tears of the medial patellofemoral ligament off the femur in 15 of 16 patients (94%). After medial patellofemoral ligament repair, none of the patients experienced recurrent dislocation. Overall 58% of the results were considered to be good or excellent and 42% were fair. Fifty-eight percent of the group returned to their previous sport with no or minor limitations.

The effect of arthrocentesis in transient synovitis of the hip in the child: a longitudinal sonographic study

Twenty-one children with transient synovitis of the hip were treated in two consecutive groups. In 12 patients aspiration of the synovial effusion was performed within 24 h of admission. In a second group of nine patients no aspiration was performed. There was no other difference in treatment. Joint effusion was studied sonographically in comparison with the nonsymptomatic contralateral hip. Sonography was performed immediately after admission, within 12 h after aspiration, and repeatedly during a follow-up period of up to 15 days. Following aspiration the capsular distention decreased to 49% but recurred within 24 h to 72% of the preoperative value. However, during the first 4 days of follow-up the capsular distention in the aspirated cases was significantly and permanently lower than in the nonaspirated cases. We conclude that arthrocentesis in the acute stage of transient synovitis of the hip in the child permanently reduces the intracapsular effusion.

Molecular mechanisms to form leukocyte infiltration patterns distinct between synovial tissue and fluid of rheumatoid arthritis

There is a striking difference in the leukocyte infiltration pattern between synovial tissue and fluid of rheumatoid arthritis, a monocyte/macrophage-predominant infiltration in the former and a polymorphonuclear leukocyte (PMN)-predominant one in the latter. In extracts of rheumatoid arthritis synovial tissue, there is a strong chemotactic activity to monocytes but a negligible one to PMNs. The monocyte-specific chemotactic factor in the extracts represents dimers (and oligomers) of the S19 ribosomal protein which are cross-linked by a transglutaminase-catalyzed reaction. This oligomer formation may correlate to apoptosis in the lesion. On the other hand, in the synovial fluids there is the co-presence of chemotactic factors effective on PMNs as well as on monocytes and a strong chemotaxis inhibitor specific to monocytes. This inhibitory molecule is C4a which is liberated from complement component 4 in the presence of immune complexes. C4a exhibits its inhibitory activity indirectly by stimulating monocytes to release an autocrine or paracrine inhibitory cytokine to monocyte chemotaxis. These molecular mechanisms seem at least partly to cause the two distinct patterns of leukocyte infiltration in rheumatoid arthritis.

[Experimental study on transplantation inside and outside tendon sheath]

The range of motion of PIP and morphological changes of tendon grafts were studied after inside outside tendon sheath grafting in rabbits. It was found that the inside tendon sheath grafting together with early postoperative mobilization healed without adhesion, and most of the cells remained viable. After outside tendon sheath grafting, the tendon cells proliferated with extensive adhesions. The range of PIP motion was greater after inside tendon sheath grafting than that after outside tendon sheath grafting. The results suggest that tendon grafting is donor-tissue-specific and the synovial layer of inside tendon sheath plays an important role in preventing adhesion formation.

Magnetic resonance imaging protocol optimization for evaluation of hyaline cartilage in the distal interphalangeal joint of fingers

RATIONALE AND OBJECTIVES

To identify a single magnetic resonance imaging (MRI) protocol that will provide optimal signal-to-noise ratio, resolution, and image contrast with minimal susceptibility artifacts and that will allow clear delineation and visualization of cartilage, fluid, bone, tendons, and ligaments within the distal interphalangeal (DIP) joint of the human hand.

METHODS

A highly optimized 2.4 T MRI system was constructed from a 31-cm horizontal bore magnet, using a solenoid radiofrequency coil. This was used to study the DIP joints of 16 healthy, asymptomatic volunteers.

RESULTS

A range of image contrast protocols were explored, including spin-echo T1 and T2, field echo, chemical shift suppression to give water only images, and magnetization transfer. Susceptibility variations were explored by changing the field strength from 0.6 to 2.4 T. A spin-echo protocol with TR = 1500 msec and TE = 30 msec can routinely produce images with resolution 0.075 x 0.150 for a slice thickness of 1 mm in 13 minutes. That protocol can visualize simultaneously compact and trabecular bone, two layers of cartilage, synovial fluid, and synovium within the joint, tendons and ligaments, and the volar plate.

CONCLUSIONS

Although the contrast is not fully optimized for any one tissue, the spin echo protocol (TR = 1500, TE = 30) provides sagittal MR images, which clearly delineate the major structures of interest within the DIP joint, and which will be used in future studies to compare changes in the DIP joint because of aging or osteoarthritis. Experience gained by applying the above methods to a total of 16 healthy, asymptomatic volunteers has enabled a single sequence to be identified, which although not optimized for any one tissue, nevertheless visualized simultaneously and clearly delineated compact and trabecular bone, two layers of cartilage, synovial fluid, and synovium within the joint.

Eosinophilic synovitis. A new entity?

The appearance and the biochemical, cytological and bacteriological findings were studied in synovial fluid obtained from the knees of 72 patients from south-west India. We report a group of 12 patients with 'eosinophilic synovitis'. In these patients, all below the age of 20 years with an acute onset of severe pain in the knee, there was a large effusion with painful limitation of movement. Their blood leucocyte count averaged 11,200 per mm3 with a mild eosinophilia of 6%. Biochemical examination of synovial fluid was normal, but cytology showed an increase in leucocytes ranging from 1200 to 20,500 (mean 9525) with between 75% and 90% of eosinophils in eight patients and 60% to 75% in four. All the patients responded well to a course of diethylcarbamazine.

Magnetic resonance imaging assessment of acute soft tissue injuries to the temporomandibular joint

PURPOSE

This study involves the use of magnetic resonance imaging (MRI) to document acute soft tissue injuries involving the temporomandibular joint (TMJ) after condylar fractures.

MATERIALS AND METHODS

Patients with condylar fractures whose clinical and radiographic examinations, as well as the mechanism of their injury, suggested specific damage to the temporomandibular soft tissues underwent MRI scanning. Thirteen patients who met selected criteria were included in this study.

RESULTS

Ten patients demonstrated disc avulsion, usually in the anterior or medial direction. Two patients had disruption of the lateral capsule, and one patient showed no MRI evidence of acute injury. Joint effusions were frequently demonstrated.

CONCLUSIONS

MRI of condylar fractures in those patients with displacement, or in whom the mechanism of injury would predispose them to posttraumatic internal derangement, may assist the clinician in determining whether primary or delayed treatment is indicated. Furthermore, MRI may be a useful resource for enhancing the level of understanding regarding soft tissue changes that occur in the TMJ after acute condylar trauma.

Knee joint effusion and proprioception

The purpose of this study was to examine the effects of excessive fluid in the knee joint on proprioception. Twenty healthy subjects with no knee pathology participated in this study. Subjects were randomly assigned to control and experimental groups. Baseline measurements of subjects performing a tracking task were then recorded. Specifically, one knee joint was moved passively by a dynamometer through a range of motion from approximately 90 degrees flexion to 10 degrees from full extension at a joint angular velocity of 60 degrees/sec. Subjects were blindfolded and required to track the passively moving joint as accurately as possible for a period of 1.25 minutes with the opposite limb. An electrogoniometer was used to monitor the motion of the active tracking limb. Ninety mL of a solution of saline and dextrose were injected into the knee joint cavity of the experimental subjects, and they repeated the tracking task. After a 5-minute rest, the control group subjects also repeated the task. The results indicated that the injection of fluid did not change the subjects' error in tracking the passively moving limb (p > 0.05). No change in the error associated with tracking was observed for the control group (p > 0.05). It is suggested that the effects of long-term effusions and the nature of the inflammatory fluid might be more responsible for the loss of proprioception observed in some clinical conditions.

Sonographic evaluation of lipohemarthrosis: clinical and in vitro study

The purpose of this study is to evaluate the role of sonography in diagnosing lipohemarthrosis. Sonography was performed on seven patients with intra-articular fractures of the knee, shoulder, and hip. An in vitro mixture of fat and blood was examined as the gold standard. In the patients scanned a few minutes after immobilization, a two-band appearance of joint effusion was present, representing a fat-blood level. One patient scanned 3 hours after immobilization showed a three-band appearance of joint effusion, corresponding to the layers of fat, serum and red blood cells. Results of this study indicate a high reliability of ultrasonography in detecting lipohemarthrosis.

Wettability and interfacial interactions in bioceramic-body-liquid systems

Wetting experiments, by the sessile drop technique, were carried out at 37 degrees C in air to determine the surface and interfacial interactions that take place in various solid bioceramics based on Al2O3, ZrO2(YPZ), SiO2, and TiO2 in contact with water, Ringer solution, artificial synovial fluid, calf serum, human plasma, and whole blood (+ EDTA). The surface energy of the liquids was measured by the ring method. The calculated values of the energy of interaction (work of adhesion) reveal that intermolecular forces act across the solid-liquid interfaces. The contribution of the dispersion and polar interactions to the surface energy of the polar liquids and the pure or mixed oxides was determined assuming that in the system of Mn-steel-liquids only dispersion forces act at the interface. It was found that the contribution of the polar interactions to the energy of interaction at the solid-liquid interface increases with the glassy phase content of the oxide that causes reduction of the measured contact angle.

Effusion criteria and clinical importance of glenohumeral joint fluid: MR imaging evaluation

PURPOSE

To investigate the clinical importance of glenohumeral joint (GHJ) fluid.

MATERIALS AND METHODS

The amount of GHJ fluid in 17 volunteers and 208 consecutive patients was graded at magnetic resonance imaging with T2-weighted fat-suppressed coronal oblique images by two blinded observers. Thorough historical data and physical examination results were available for 108 patients. Presence and grade of GHJ fluid were correlated with age, sex, presence of osteophytes activity scale, supraspinatus tenderness, clinical impingement, prior subacromial injections, rotator cuff tears (RCTs), joint tenderness, joint pain, and history of trauma.

RESULTS

GHJ fluid was seen in 40% (n = 83) of patients and in only 6% (n = 1) of volunteers. The volume of fluid correlated with osteophytes (P = .04), increasing age (P = .0001), and RCTs (P = .005). No correlation was found with activity rating, focal tenderness, joint pain, diagnosis of impingement, impingement grade, supraspinatus insertional tenderness, subacromial injection, prior trauma, or sex.

CONCLUSION

The presence of GHJ fluid appears to be abnormal and in most cases is related to RCTs and osteoarthritis. It seems to be unrelated to activity, tenderness, or impingement.

Pigmented villonodular synovitis: MRI characteristics

The magnetic resonance imaging (MRI) scans of 26 patients with histopathologically proven pigmented villonodular synovitis (PVNS), involving joints but excluding tendon sheaths, were reviewed retrospectively. The purpose of this study is to define the spectrum and frequency of MRI characteristics for PVNS using conventional spin echo (in two cases before and after intravenous administration of gadopentate dimeglumine) and also gradient echo techniques. A cystic variety is presented, the MRI appearances of which have not been found in a review of the literature.

Methods and errors in measurements of synovial fluid volume in stifles with low volume and high viscosity synovial fluid. An experimental study in goats

Synovial fluid (SF) volume was calculated using various methods in the stifles of goats, in which the cranial cruciate ligament had been transected on one side. Measurements were performed prior to surgery and again 4, 8, and 18 weeks following surgery, by measuring the dilution of an injected radioactive tracer diluted by the SF. Later, 7 months following surgery, SF volume measurements using simple arthrocentesis were performed on stifles in 9 of the goats, and the SF that could not be aspirated, was calculated using 2 indirect methods simultaneously on identical fluids in 3 of these goats. SF was also collected directly during staged arthrotomy of the stifles in 4 goats. There were conflicting results between methods, but the resulting calculated SF volumes seemed to be larger in the operated stifles compared to the controls for all the methods at about the same degree. The 2 indirect methods used to calculate the fluid remaining in the joints following arthrocentesis gave disparate volume calculations. The experiments revealed sources of error in all methods. Direct methods failed to acquire the total fluid volume, and indirect methods were subject to improper mixing and escape of the injected fluid or synovial fluid or both. It was concluded that none of the methods could be used to measure the "true" volume of SF, if such a concept exists and can be defined. None of the methods were considered reliable to compare volumes in different type of joints containing this type of fluid. It was, however, concluded that all the methods gave indication of increased SF volume present on a relative basis when paired joints were compared.

[A role for lipoproteins in the recovery from CPPD crystal-induced arthritis]

Calcium pyrophosphate dihydrate (CPPD) crystal-induced inflammation subsides spontaneously, and there have been few reports on its mechanism. It has recently been proposed that lipoproteins in the inflammatory synovial fluid played a role in the recovery from crystal-induced arthritis. This study investigated the inhibitory effect of lipoprotein on the inflammation-inducing activity of CPPD crystals in vitro and in vivo. Lipoproteins (very low density lipoprotein--VLDL, and low density lipoprotein-LDL) were isolated from human serum (in vitro) and rat serum (in vivo) by the sequential ultracentrifugal technique. In the in vitro studies, saline with lipoproteins was mixed with CPPD crystals, and co-incubated with isolated polymorphonuclear leukocytes (PMN). The production of superoxide anion (O-(2)) was measured as an index of inflammatory activity. In the in vivo studies, suspensions of CPPD crystals and rat lipoprotein solutions, were injected into the rat air pouch. The total number of white blood cells (WBC), crystal-containing WBCs, and concentrations of beta-glucronidase and prostaglandin (PG) E2, were measured. In the in vitro studies, O-(2) production by PMNs was more significantly suppressed after treating the CPPD crystals with VLDL or LDL than when the crystals were not treated with VLDL or LDL. In the in vivo studies, treatment of the CPPD crystals with lipoproteins significantly decreased the number of WBC and crystal-containing WBC, as well as the concentration of beta-glucronidase, and tended to depress the concentration of PGE2. These findings suggested that lipoproteins, especially LDL in inflammatory synovial fluid played an important role in the recovery from CPPD crystal-induced arthritis.

Fat-suppressed spoiled GRASS imaging of knee hyaline cartilage: technique optimization and comparison with conventional MR imaging

OBJECTIVE

We studied healthy volunteers with fat-suppressed three-dimensional (3D) spoiled gradient-recalled acquisition in the steady state (SPGR) to determine parameters that maximize positive contrast between knee articular cartilage and fluid, marrow fat, and muscle; and we compared the technique with conventional MR imaging sequences. The purpose was to determine if fat-suppressed 3D SPGR imaging is useful for detecting abnormalities of the articular cartilages.

SUBJECTS AND METHODS

The knees of 10 healthy volunteers were imaged in the axial plane. Fat-suppressed 3D SPGR imaging was performed with a TR of 60 msec, a TE ranging from 5 to 15 msec, and a flip angle ranging from 20 degrees to 80 degrees. This was followed by a similar set of fat-suppressed two-dimensional (2D) SPGR images, and conventional T1- and T2-weighted spin-echo and multiplanar gradient studies. Contrast-to-noise (C/N) ratios were determined for cartilage versus a saline fluid phantom, marrow fat, and muscle. Optimal parameters were determined both quantitatively and by a blinded subjective analysis.

RESULTS

A TE of 5 msec and a flip angle of 40 degrees demonstrated the greatest C/N ratio between the signals for cartilage and for fluid, marrow, and muscle. C/N ratios in the 3D sequences were higher than in the 2D, spin-echo, and gradient series, although the absolute C/N ratio values for the T2-weighted spin-echo sequence were higher than those for the 3D fat-suppressed SPGR sequence. Subjective analysis showed articular cartilage to have a consistent trilaminar appearance, and independent interpreters favored a 3D fat-suppressed SPGR sequence with a TE of 5 msec and a flip angle of 40 degrees. Three subjects with incidental joint fluid had C/N ratios within a 95% confidence range for cartilage versus the fluid phantom.

CONCLUSION

When a fat-suppressed 3D SPGR sequence of 60/5/40 degrees (TR/TE/flip angle) is used, MR images can show high positive contrast between articular hyaline cartilage and adjacent structures. This convenient technique is different from standard MR imaging sequences because it demonstrates greater signal intensity in cartilage than in fluid, marrow fat, and muscle, and because it consistently shows an organized internal architecture of hyaline cartilage. Fat-suppressed 3D SPGR imaging therefore has promise for detecting abnormalities of the articular cartilage.