OARSI Clinical Trials Recommendations: Knee imaging in clinical trials in osteoarthritis.

Significant advances have occurred in our understanding of the pathogenesis of knee osteoarthritis (OA) and some recent trials have demonstrated the potential for modification of the disease course. The purpose of this expert opinion, consensus driven exercise is to provide detail on how one might use and apply knee imaging in knee OA trials. It includes information on acquisition methods/techniques (including guidance on positioning for radiography, sequence/protocol recommendations/hardware for magnetic resonance imaging (MRI)); commonly encountered problems (including positioning, hardware and coil failures, sequences artifacts); quality assurance (QA)/control procedures; measurement methods; measurement performance (reliability, responsiveness, validity); recommendations for trials; and research recommendations.

Basic anatomy of the shoulder by magnetic resonance imaging.

An understanding of the normal magnetic resonance (MR) infrastructural details of musculotendinous elements of the rotator cuff forms the basis for analysis of its pathology. The muscular bellies of the teres minor, infraspinatus, supraspinatus, and subscapularis are easily identified in MR images. In their lateral course both the supraspinatus and infraspinatus muscles transition to tendons gradually. Their lateral tendinous portions partially overlap and form a layered appearance on MR images. The subscapularis, with its fan-like tendinous insertional slips at the lesser tuberosity, can be identified easily in all imaging planes. The ligamentous structures of the shoulder, including the coracoacromial and coracohumeral ligaments, are visualized as low signal bands in all imaging planes. The capsuloligamentous structures including the superior, middle, and inferior glenohumeral ligament and glenoid labrum present considerable anatomic variations. This is especially true with respect to the anterior labrum, which varies from absent to a well-formed triangular appearance. Understanding the basic MRI anatomy of all soft tissue structures of the shoulder is essential for appropriate interpretation of lesions related to the shoulder.

Preliminary results of a modified surface rendering technique in the display of magnetic resonance angiography images.

Maximum intensity projections are the currently accepted method of displaying Magnetic resonance angiography (MRA) data. In this study, we introduce a modified surface rendering method for displaying this same MRA data. The system we have developed is designed to reconstruct three-dimensional (3D) images of vasculature using standard magnetic resonance images. A workstation was used for post-processing that is readily available and inexpensive. Software was written to process the original images and control the commercially available surface rendering algorithm while performing the reconstruction. The standard surface rendering technique was modified by including several velocities of blood flow in the reconstruction. These velocities were assigned varying degrees of translucency, which allow flow information to be included in the reconstructed images. Six subjects were examined using this technique and the images were compared with those from other imaging modalities. This surface rendering method has been shown to produce clearer and more comprehensible images of complex vasculature, both for radiologists, and for physicians of other disciplines. Its success is based on improvements in computing techniques and in acquisition of vascular MR images. The method shows great potential, and with future clinical trials, the true uses of this method will be discovered or confirmed.

MR imaging of rabbit hip cartilage with a clinical imager and specifically designed surface coils.

RATIONALE AND OBJECTIVES: The authors' purpose was to develop a magnetic resonance (MR) imaging technique for examining the hip joint of a rabbit with a clinical MR imager. MATERIALS AND METHODS: Fourteen hips of 10 male New Zealand white rabbits were examined on a 1.5-T MR imager with a specially designed surface coil. Field of view was 3-8 cm, matrix was 256-512 x 192-256, section thickness was 0.9-2.0 mm, and spacing was 0.3-0.5 mm. The hips were sectioned and evaluated by means of light microscopy. Measurements of cartilage thickness from MR images were correlated with those from histologic specimens. RESULTS: The resolution obtainable with a 1.5-T imager was adequate for imaging articular cartilage when a débrided rabbit hip specimen was placed in the center of a 3.5-cm single-loop coil. Rabbit hip cartilage had a trilaminar appearance on MR images. The coefficient of correlation between cartilage-thickness measurements was .81. CONCLUSION: MR imaging of rabbit hip cartilage can be performed on 1.5-T clinical MR imaging unit. Limitations due to the field strength can be overcome with efficiently designed surface coils.

MR imaging of the triangular fibrocartilage complex.

This article describes in detail the anatomic components of normal triangular fibrocartilage complex (TFCC) and its MR appearance on high resolution MR images. It also describes pathologic processes of TFCC and its MR appearance.

Iatrogenic false aneurysms following punch hair grafting.

By serial angiograms, we found the pulsating nodules occasionally seen after punch hair grafting are pseudoaneurysms.

MRI findings of scapholunate instabilities in coronal images: a short communication.

The plain radiographic findings of scapholunate instabilities are very well described in the literature. However, even though the same phenomena that are seen in plain radiographs are also seen in magnetic resonance (MR) images, there are very few reports in the literature regarding MRI findings in scapholunate instabilities. This short communication describes the findings seen in coronal MR images in advanced scapholunate instabilities.

Scapholunate ligament: normal MR appearance on three-dimensional gradient-recalled-echo images.

PURPOSE: To evaluate the (a) capability of coronal three-dimensional (3D) gradient-recalled-echo (GRE) images in the demonstration of the volar, middle, and dorsal portions of the scapholunate ligament (SLL); (b) normal magnetic resonance (MR) appearance of these portions and of their attachment to the lunate and scaphoid; and (c) normal appearance of the ligament-cartilage interface for various portions of the SLL. MATERIALS AND METHODS: Coronal 3D GRE imaging was used to study the volar, middle, and dorsal portions of the SLL in 14 patients with an arthroscopically normal SLL and in five cadaveric wrists that had a normal SLL proved with dissection. RESULTS: The trapezoidal volar portion of the SLL was seen with inhomogeneous high intermediate signal intensity and attached directly to the lunate and scaphoid cortex. The triangular middle portion was seen with inhomogeneous intermediate signal intensity and in most cases attached to the hyaline cartilage of the lunate and scaphoid. The low-signal-intensity bandlike dorsal portion attached either to the cartilage, cartilage and cortex, or cortex alone of the lunate and scaphoid. CONCLUSION: The volar, middle, and dorsal portions of the SLL can be differentiated on the basis of MR appearance on 3D GRE images. The various portions attach to cartilage and/or to cortex, and the appearance of the ligament-cartilage interface follows a specific pattern.

Triangular fibrocartilage complex: normal appearance on coronal three-dimensional gradient-recalled-echo MR images.

PURPOSE: To evaluate the usefulness of three-dimensional gradient-recalled-echo (GRE) sequences in demonstration of the triangular fibrocartilage complex (TFCC). MATERIALS AND METHODS: Appearance of the TFCC in wrists of 11 cadavers, 17 patients, and six volunteers at three-dimensional GRE magnetic resonance (MR) imaging was evaluated and compared with that at dissection. RESULTS: MR appearance of the TFCC was similar for all wrists. Volar and dorsal radioulnar ligaments were identified. The TFCC had two types of attachments to the ulna: The more common consisted of two striated attachments, one to the tip and the other to the base of the styloid; the less common consisted of a broad-based striated attachment along the styloid. MR appearance of the ulnotriquetral and ulnolunate ligaments and meniscus homologue varied but correlated with observations at dissection. CONCLUSION: The three-dimensional GRE sequence consistently demonstrated most TFCC components. Dissection helped confirm MR-demonstrable variability in the ulnar aspect of the TFCC.

3D interleaved water and fat image acquisition with chemical-shift correction.

A new technique, 3D interleaved water and fat image acquisition with chemical-shift correction (3-DIWFAC), was developed to acquire 3D water and fat images in a single acquisition time and to combine the water and fat images to produce chemical-shift-free images. A 3D gradient-recalled-echo (GRE) sequence was implemented with a 1-3-3-1 binomial Shinnar-Le Roux spatial-spectral excitation, and with interleaved phase-encoding lines that alternate between water and fat excitations separated by half TR. Water-only and fat-only images were then realigned to remove chemical shift artifacts. Results from phantoms and human subjects demonstrated that the image contrast was the same as in the regular GRE sequence. With the chemical shift corrected, the shadow artifacts often seen at water and fat boundaries were removed. Since this sequence simultaneously provides water-only images showing cartilage and bone lesions, and water-fat images that depict soft tissue anatomy, it may be clinically useful in musculoskeletal imaging. Magn Reson Med 44:322-330, 2000.

Interleaved water and fat dual-echo spin echo imaging with intrinsic chemical-shift elimination.

A new technique was developed to simultaneously acquire water and fat dual-echo spin echo images in a single acquisition period. Chemical shifts between water and fat images are intrinsically eliminated, and the images are combined to form water-plus-fat image. In vivo water-only images show fat suppression superior to that of conventional spin echo images. This technique may be clinically useful for musculoskeletal imaging.

Computed tomography of pyonephrosis.

Computed tomographic (CT) findings of 17 pyonephrotic and 20 uninfected hydronephrotic kidneys were reviewed. Parameters evaluated included: renal pelvic wall thickness (none; grade 1, < or = 2 mm; grade 2, 3-5 mm; and grade 3, > 5 mm), renal pelvic contents, parenchymal, and perirenal findings. All patients underwent subsequent percutaneous nephrostomy within 1 week of CT. Common CT findings suggesting pyonephrosis include increased pelvic wall thickness and more severe perirenal fat changes than are seen in uninfected hydronephrosis. However, for any one patient, these findings are often not diagnostic. The presence of clinical signs of infection with hydronephrosis on CT is a more sensitive indicator of pyonephrosis than most CT findings.

Flow compensation in MRI using a phase-corrected real reconstruction.

Flow- and motion-related artifacts are problematic in clinical MR imaging. In this paper we discuss the utility of a phase-corrected real reconstruction to reduce flow artifacts. This technique is particularly useful when flow-compensation pulse sequences may not be possible, such as when a very short echo delay or small field-of-view is desired. We will demonstrate that the phase-corrected real reconstruction provides superior results to the magnitude reconstruction either used alone or in conjunction with existing flow-compensation techniques.

Magnetic resonance imaging of the hip with a pelvic phased-array surface coil: a technical note.

OBJECTIVE: The aim of this study was to assess the capability of high-resolution images obtained with a commercially available pelvic phased-array surface coil to demonstrate normal hip anatomy. DESIGN: We retrospectively analyzed the oblique coronal magnetic resonance (MR) images of hips of 36 consecutive patients acquired on a 1.5-T clinical imager using a pelvic phased-array coil as a receiver, a 16-20 cm field of view, and 5 mm slice thickness. PATIENTS: Thirty-six patients were studied, age 15-81 years. There were 20 males and 16 females. RESULTS AND CONCLUSIONS: The articular cartilage, cortex, superior labrum, and iliofemoral ligament were well visualized on proton density weighted fat saturation (PDF) images. The femoral and obturator vessels, obturator nerve, and various muscles were easily seen on T1-weighted images. High-resolution imaging of the hip is achievable in a reasonable amount of time using newer phased-array surface coils and may play an increasing role in the future evaluation of hip disorders.

Lesions of the triangular fibrocartilage complex: MR findings with a three-dimensional gradient-recalled-echo sequence.

PURPOSE: To evaluate the use of a three-dimensional gradient-recalled-echo (GRE) magnetic resonance (MR) imaging sequence in the depiction of lesions of the triangular fibrocartilage (TFC) complex. MATERIALS AND METHODS: MR images of the TFC complex were evaluated in 31 patients who underwent wrist arthroscopy less than 6 months after MR imaging. The results were compared with the arthroscopic findings. RESULTS: Eleven of 12 full-thickness TFC tears were depicted, but one partial-thickness tear, one abnormal disk, and one normal disk were overstaged. Lesions in the volar and dorsal radioulnar ligament and lesions of the attachments of the TFC complex to the ulna often were overstaged. Lesions of the ulnolunate and ulnotriquetral ligaments often were understaged. CONCLUSION: Imaging with the three-dimensional GRE sequence is reliable in the depiction of TFC tears and the exclusion of tears of components of the TFC complex other than those of the ulnolunate and ulnotriquetral ligaments.

A volume adjustable four-coil phased array for high resolution MR imaging of the hip.

A four-coil phased array was specifically designed and built for MR imaging of the hip at 1.5 T. Its RF and imaging properties were evaluated using phantom and in-vivo studies and the results were compared to those of three different commercial coils commonly used for hip imaging. Our coil gave a significantly higher S/N at anatomic locations commonly evaluated for hip diagnosis. The increased S/N supports higher image spatial resolution and improves the visualization of fractures and lateral injuries.

Intrinsic and extrinsic carpal ligaments: evaluation by three-dimensional Fourier transform MR imaging.

OBJECTIVE: As evaluation of the anatomic and functional integrity of intrinsic and extrinsic carpal ligaments with conventional imaging methods is difficult, we designed a study to evaluate the ability of three-dimensional Fourier transform MR imaging to show the carpal ligaments. SUBJECTS AND METHODS: We obtained coronal MR images of 15 cadaveric wrists and 15 wrists of patients, using three-dimensional volume acquisition with a gradient-recalled echo sequence and a 1.5-T magnet. The MR findings were compared with the findings on dissection in the 15 cadaveric wrists and with the surgical findings in eight patients. RESULTS: All the volar ligaments had a striated appearance on MR images, with alternating bands of low and intermediate signal intensity. No tears of the extrinsic ligaments were seen. The intrinsic scapholunate and lunotriquetral ligaments were seen as structures with more homogeneously intermediate intensity attaching to their adjacent bone through high-signal-intensity hyaline cartilage. For the cadaveric wrists, MR indications of a tear of the scapholunate ligament were true-positive in three and false-negative in three; indications of a tear of the lunotriquetral ligament were true-positive in five, false-positive in two, and false-negative in one. For the eight patients with surgical confirmation, the MR findings regarding tears were true-positive in two and true-negative in six. Neither surgery nor MR imaging showed any tears of the scapholunate ligament. CONCLUSION: Three-dimensional Fourier transform MR imaging with thin slices provides the resolution necessary to visualize the anatomic detail of the extrinsic and intrinsic ligaments of the wrist, but additional clinical experience with this technique will be required to determine its diagnostic capabilities.

Classification of trabecular structure in magnetic resonance images based on morphological granulometries.

A new method of detecting structured changes in trabecular bone, such as those associated with osteoporosis, was evaluated on magnetic resonance images of the wrist. The method was based on gray-scale morphological granulometries which classify image texture by iteratively filtering an image and measuring the rate of change of structural diminution in a filtered-image sequence. A classification scheme capable of distinguishing structural changes in trabecular bone starting from normal trabeculae through sclerotic, cystic, and grossly porotic bone is presented. Results of the application of this technique to the evaluation of high resolution magnetic resonance images of the wrist are presented.

Rheumatoid arthritis: evaluation of wrist extensor tendons with clinical examination versus MR imaging--a preliminary report.

To determine whether magnetic resonance (MR) imaging can improve assessment of the extensor tendons of the wrist and their propensity to rupture, the dorsal tendons in 23 wrists in 20 patients with rheumatoid arthritis were clinically assessed and then examined with MR imaging. Clinical and MR imaging evaluations were performed blindly and independently. The six extensor tendon compartments were assessed with MR imaging for presence of pannus, synovial effusion, and tendon involvement or rupture. Clinical scores of systemic disease, dorsal tendon sheath swelling, and risk of tendon rupture ranged from 0 to 3 in each category; the overall score was not associated with any MR imaging category. Clinical assessment of enlargement of the dorsal tendon sheath and clinical risk of rupture correlated poorly with findings on MR images. All eight wrists with clinically minimal risk of rupture had pannus, effusions, and tendon involvement on MR images; the findings were similar in the wrists with moderate (grade 2) risk of rupture. MR imaging depicts involvement of the dorsal tendon sheath and dorsal tendons that cannot be assessed with other radiologic or clinical means.

Meniscal subluxation: association with osteoarthritis and joint space narrowing.

OBJECTIVE: Since complete meniscectomy leads to knee OA, we investigated the potential links among meniscal subluxation, joint space narrowing and symptomatic OA. MATERIALS AND METHODS: 233 cases with symptomatic knee OA and 58 asymptomatic controls underwent radiography and MR imaging of the knee. Joint space narrowing was measured on weight-bearing PA fluoroscopy-positioned radiographs. The amount of medial or lateral meniscal subluxation was measured on coronal MR images. The prevalence and severity of meniscal subluxation was compared in cases and controls. We evaluated the correlation of the degree of meniscal subluxation with joint space narrowing, Kellgren and Lawrence grade, and two major risk factors for the development of OA, age and weight. RESULTS: Cases had more medial and lateral subluxation than controls. Mean medial meniscal subluxation was 5.1 mm in cases and 2.8 mm in controls (P=0.001). Modest degrees of meniscal subluxation were common in both cases and controls: 81% of cases and 64% of controls had >/=3 mm of subluxation; age and gender adjusted (P=0.006). Severe degrees of subluxation were almost unique to OA cases (e.g. prevalence of >/=7 mm, 35% cases vs. 7% controls, P< 0.001). Among controls, severe degrees of subluxation were present only in those with radiographic joint space narrowing (defined as >/=grade 1 narrowing on a 0-3 scale). In cases, there was a strong correlation between the degree of medial meniscal subluxation and the severity of medial joint space narrowing (r=0.56, P=0.0001). Similar results were present in the lateral compartment. Meniscal subluxation did not correlate with age or weight. CONCLUSION: Meniscal subluxation is highly associated with symptomatic knee OA. In subjects with osteoarthritis, increasing meniscal subluxation on MR correlates with the severity of joint space narrowing.