Radiocarpal Injuries: Cone Beam Computed Tomography Arthrography, Magnetic Resonance Arthrography, and Arthroscopic Correlation among 21 Patients.

BACKGROUND AND AIMS: Patients with acute or chronic wrist pain often undergo wrist arthroscopy for evaluation of chondral and ligamentous abnormalities. The purpose of this study was to compare findings of wrist arthroscopy with cone beam computed tomography arthrography and magnetic resonance arthrography. MATERIALS AND METHODS: Altogether, 21 patients with wrist pain underwent cone beam computed tomography arthrography, magnetic resonance arthrography, and wrist arthroscopy. Chondral surfaces of the scaphoid, lunate, and radius facing the scaphoid and lunate were evaluated. The scapholunate ligament, the lunotriquetral ligament, and the triangular fibrocartilage complex were classified as either intact or torn. Sensitivity, specificity, positive and negative predictive values, and accuracy with 95% confidence intervals were assessed. RESULTS: For chondral lesions (n = 10), cone beam computed tomography arthrograms showed slightly higher specificity than magnetic resonance arthrography. The sensitivity of cone beam computed tomography arthrography was also better for these lesions, except for those on the chondral surface of the lunate. For triangular fibrocartilage complex injuries (n = 9), cone beam computed tomography arthrography showed a better specificity and sensitivity than magnetic resonance arthrography. For ligamentous injuries (n = 6), cone beam computed tomography arthrograms were more sensitive, but less specific than magnetic resonance arthrography images. However, the number of lesions was very small and the 95% confidence intervals are overlapping. CONCLUSION: Cone beam computed tomography is an emerging imaging modality that offers several advantages over computed tomography and magnetic resonance imaging. Its usefulness particularly in ligamentous injuries should be further explored in a larger study. Cone beam computed tomography arthrography seems to offer similar sensitivity, specificity, and accuracy compared to magnetic resonance arthrography and therefore serves as a valuable option in evaluating patients with wrist pain.

Whole body computed tomography for trauma patients in the Nordic countries 2014: survey shows significant differences and a need for common guidelines.

BACKGROUND: Whole body computed tomography in trauma (WBCTT) is a standardized CT examination of trauma patients. It has a relatively high radiation dose. Therefore, well-defined clinical indications and imaging protocols are needed. This information regarding Nordic countries is limited. PURPOSE: To identify Nordic countries' WBCTT imaging protocols, radiation dose, and integration in trauma care, and to inquire about the need for common Nordic guidelines. MATERIAL AND METHODS: A survey with 23 multiple choice questions or free text responses was sent to 95 hospitals and 10 trauma centers in and outside the Nordic region, respectively. The questions were defined and the hospitals selected in collaboration with board members of "Nordic Forum for Trauma and Emergency Radiology" (www.nordictraumarad.com). RESULTS: Two Nordic hospitals declined to take part in the survey. Out of the remaining 93 Nordic hospitals, 56 completed the questionnaire. Arterial visualization is routine in major trauma centers but only in 50% of the Nordic hospitals. The CT scanner is located within 50 m of the emergency department in all non-Nordic trauma centers but only in 60% of Nordic hospitals. Radiation dose for WBCTT is in the range of 900-3600 mGy × cm. Of the 56 responding Nordic hospitals, 84% have official guidelines for WBCTT. Eighty-nine percent of the responders state there is a need for common guidelines. CONCLUSION: Scanning protocols, radiation doses, and routines differ significantly between hospitals and trauma centers. Guideline for WBCTT is presently defined locally in most Nordic hospitals. There is an interest in most Nordic hospitals to endorse new and common guidelines for WBCTT.

Radiographical measurements for distal intra-articular fractures of the radius using plain radiographs and cone beam computed tomography images.

OBJECTIVE: Operative treatment of an intra-articular distal radius fracture is one of the most common procedures in orthopedic and hand surgery. The intra- and interobserver agreement of common radiographical measurements of these fractures using cone beam computed tomography (CBCT) and plain radiographs were evaluated. MATERIALS AND METHODS: Thirty-seven patients undergoing open reduction and volar fixation for a distal radius fracture were studied. Two radiologists analyzed the preoperative radiographs and CBCT images. Agreement of the measurements was subjected to intra-class correlation coefficient and the Bland-Altman analyses. RESULTS: Plain radiographs provided a slightly poorer level of agreement. For fracture diastasis, excellent intraobserver agreement was achieved for radiographs and good or excellent agreement for CBCT, compared to poor interobserver agreement (ICC 0.334) for radiographs and good interobserver agreement (ICC 0.621) for CBCT images. The Bland-Altman analyses indicated a small mean difference between the measurements but rather large variation using both imaging methods, especially in angular measurements. CONCLUSIONS: For most of the measurements, radiographs do well, and may be used in clinical practice. Two different measurements by the same reader or by two different readers can lead to different decisions, and therefore a standardization of the measurements is imperative. More detailed analysis of articular surface needs cross-sectional imaging modalities.

The usefulness of MRI and arthroscopy in the diagnosis and treatment of soft-tissue injuries associated with split-depression fractures of the lateral tibial condyle.

The role of arthroscopy in the treatment of soft-tissue injuries associated with proximal tibial fractures remains debatable. Our hypothesis was that MRI over-diagnoses clinically relevant associated soft-tissue injuries. This prospective study involved 50 consecutive patients who underwent surgical treatment for a split-depression fracture of the lateral tibial condyle (AO/OTA type B3.1). The mean age of patients was 50 years (23 to 86) and 27 (54%) were female. All patients had MRI and arthroscopy. Arthroscopy identified 12 tears of the lateral meniscus, including eight bucket-handle tears that were sutured and four that were resected, as well as six tears of the medial meniscus, of which five were resected. Lateral meniscal injuries were diagnosed on MRI in four of 12 patients, yielding an overall sensitivity of 33% (95% confidence interval (CI) 11 to 65). Specificity was 76% (95% CI 59 to 88), with nine tears diagnosed among 38 menisci that did not contain a tear. MRI identified medial meniscal injuries in four of six patients, yielding an overall sensitivity of 67% (95% CI 24 to 94). Specificity was 66% (95% CI 50 to 79), with 15 tears diagnosed in 44 menisci that did not contain tears. MRI appears to offer only a marginal benefit as the specificity and sensitivity for diagnosing meniscal injuries are poor in patients with a fracture. There were fewer arthroscopically-confirmed associated lesions than reported previously in MRI studies.

Factors predicting the development of early osteoarthritis following lateral tibial plateau fractures: mid-term clinical and radiographic outcomes of 73 operatively treated patients.

BACKGROUND AND AIMS: The indications for operative treatment of lateral tibial plateau fractures are still controversial. The objective of this study was to determine whether residual articular surface depression and valgus malalignment of plated lateral tibial plateau fractures at medium-term follow-up affect the clinical and radiographic outcomes. MATERIAL AND METHODS: A chart review of patients with operatively treated (AO type B3.1) tibial plateau fractures that were admitted to our level I trauma center between 2002 and 2008 was performed. Out of 123 patients, 73 were available to participate in a clinical and radiographic follow-up examination. The mean follow-up time was 54 months. Patients were clinically assessed and completed the Lysholm knee score and Western Ontario and McMaster Universities Osteoarthritis Index. Maximal articular surface depression, radiological mechanical axis, and degree of posttraumatic osteoarthritis were evaluated from standing radiographs. RESULTS: Patients with valgus malalignment of 5° or greater at follow-up developed more advanced osteoarthritis (Kellgren-Lawrence grade 3-4) than patients with a normal mechanical axis (p = 0.006). Similarly, patients with articular depression greater than 2 mm at follow-up also developed more advanced osteoarthritis compared to patients with a depression of 2 mm or less (p = 0.001). The degree of valgus malalignment or articular depression had no effect on the Western Ontario and McMaster Universities Osteoarthritis Index or Lysholm scores. CONCLUSIONS: The postoperative articular congruity and normal mechanical axis of the lower leg after plate fixation in lateral tibial plateau fractures seem to have a role in prevention of posttraumatic osteoarthritis but does not appear to predict clinical outcome at medium-term follow-up. The role of initial dislocation and associated cartilage damage in the development of osteoarthritis following these fractures is still unknown.

Violence-related facial trauma: analysis of multidetector computed tomography findings of 727 patients.

OBJECTIVES: The multidetector CT (MDCT) findings of facial trauma in victims of interpersonal violence were assessed. METHODS: All MDCT requests for suspected facial injury during a 62 month period were retrieved; 727 cases met the inclusion criteria. Images were interpreted by two researchers by consensus. RESULTS: Of the 727 patients (aged 15-86 years old, mean 37), 583 (80.2%) were male and 144 (19.8%) female. Of all the patients, 74% had a fracture, and of these 44% had multiple non-contiguous fractures. CONCLUSIONS: Violence is a very common cause of facial injury. Nasal and orbital fractures predominate. Males are more often involved; they are younger, sustain fractures more often and significantly more often present with high-energy fracture patterns. LeFort fractures are often unilateral or asymmetrical, and are frequently accompanied by other, clinically significant fractures. Up to 25% of patients with fractures do not have paranasal sinus effusions.

Is subcutaneous local anesthesia in shoulder magnetic resonance arthrography necessary?

BACKGROUND: Magnetic resonance arthrography is a well-established diagnostic method in degenerative and traumatic disorders of the shoulder. Some radiologists prefer to apply a local anesthetic to the skin prior to performing the joint puncture. However, no information regarding the efficacy of local anesthetics exists. PURPOSE: To assess patient discomfort in arthrography injection. MATERIAL AND METHODS: A patient survey (n = 74) utilizing a visual analog scale (VAS) measured the intensity of pain in arthrography injection by those receiving local anesthetics (n = 36) versus those who did not (n = 38). RESULTS: Mean VAS scores were 20.8 (median 10.5, SD 24.3) for those receiving local anesthetics versus 19.3 (median 13.0, SD 20.7) for those who did not (P = 0.83, Mann-Whitney U test). CONCLUSION: Routine use of local anesthesia of the skin in arthrography injection is unnecessary.

Multidetector computed tomography imaging of facial trauma in accidental falls from heights.

PURPOSE: To assess multidetector computed tomography (MDCT) findings in facial trauma in adults who accidentally fall from heights. MATERIAL AND METHODS: Of the MDCT scans of 2413 cases requested by emergency-room physicians for suspected facial injury, 155 (age 15.3-76.7, mean 42.0 years; 134 male, 21 female) met the criteria of falling from heights. These were reviewed by two researchers by consensus. RESULTS: Of these 155, 118 (104 male, 14 female) had 247 fractures, while 37 had no fracture. The fractures were classified into 13 categories, the zygomatic complex being the region most frequently involved. Mean falling height, known in 132 of 155 cases, was 5.7 m (range 0.4-25) in all, 6.0 m (0.4-25) in those suffering a fracture, and 5.0 m (range 0.4-13) in those without a fracture. Patients with Le Fort II, Le Fort III, or frontal bone fractures had fallen higher and frequently had associated skull base fractures, but with considerable overlap in falling heights. Zygomatic arch and nasal bone fractures rarely occurred solitarily. CONCLUSION: In a fall-from-height injury, nasal bone and zygomatic arch fractures indicate the presence of more severe fractures. Height cannot solely predict injury probability. Clear sinus sign is a valuable aid in assessing midface trauma in falls from heights.

Multidetector computed tomography in acute knee injuries: assessment of cruciate ligaments with magnetic resonance imaging correlation.

PURPOSE: To evaluate whether non-contrast multidetector computed tomography (MDCT) for suspected acute knee fractures can also be used to evaluate cruciate ligament pathology. MATERIAL AND METHODS: A total of 42 patients (17-65 years) underwent four-section MDCT. The images were independently evaluated at clinical workstations by four radiologists. They assessed the integrity (normal or torn) and the best slice direction (axial, sagittal, or coronal) for visualization of the cruciate ligaments. Magnetic resonance imaging (MRI), performed within 4 weeks (mean 6 days) in relation to MDCT, was considered the gold standard. RESULTS: Ligament integrity at MDCT: the mean interobserver proportion of agreement for a normal anterior cruciate ligament (ACL) was 0.73, for a torn ACL 0.41, for a normal posterior cruciate ligament (PCL) 0.96, and for a torn PCL 0.54. Interobserver variation for ACL was significant (P = 0.0136-0.0260), but insignificant for PCL (P = 0.3389-0.7212). Intra-observer variation was insignificant. Visualization was best in the axial and sagittal direction for ACL and PCL, respectively. At MRI, 29 normal, one partially, and 12 completely torn ACLs, and 37 normal, four partially and one completely torn PCL were found. CONCLUSION: MDCT can detect an intact ACL and PCL with good specificity, accuracy, and negative predictive value. The assessment of torn ligaments is unreliable.

Multidetector computed tomography in acute joint fractures.

Conventional radiography plays an essential diagnostic role in the primary evaluation of acute joint trauma. In complex fractures, however, computed tomography (CT) is an imaging modality often used second to radiography. As a result of technical breakthroughs in the field, multidetector CT (MDCT) allows faster imaging and better temporal, spatial, and contrast resolution compared with conventional single-slice spiral CT. MDCT with multiplanar reformation is helpful in disclosing fracture patterns, particularly in complex joint fractures, where they reveal occult fractures and show the exact number of fracture components and their degree of displacement.

Evaluation of flexion/extension of the upper cervical spine in patients with rheumatoid arthritis: an MRI study with a dedicated positioning device compared to conventional radiographs.

PURPOSE: Using flexion/extension magnetic resonance imaging (MRI) with a dedicated positioning device, our purpose was to analyze pathologic cranio-vertebral joint anatomy and motion in patients with rheumatoid arthritis in comparison to normal patients, and to compare flexion/extension MRI with conventional radiographs (CRs) in patients with rheumatoid arthritis. MATERIAL AND METHODS: The 31 patients with rheumatoid arthritis and 20 healthy subjects included in the study were imaged in an open MRI scanner during flexion/extension. A dedicated positioning device was used. Additionally, we compared flexion/extension MRI with CRs in patients with rheumatoid arthritis. In MRI, the orientation and segmental motion of C0, C1, and C2 were assessed and structure of the dens and amount of pannus tissue were observed. Configuration of the cerebrospinal fluid space and the cord was evaluated in each position. In both MRI and CRs, anterior atlanto-axial subluxation and vertical dislocation were assessed and sagittal diameter of the dural sac was measured. RESULTS: In the neutral position, C1 of the patients was oriented in a more flexed position in relation to both C0 and C2 compared to that in healthy subjects. The patients had more extension in the upper cervical spine than did healthy subjects. In flexion, atlantoaxial subluxation was greater in CRs than in MRI. In MRI, the amount of vertical dislocation did not depend on position. In the patients, there was considerably more cord impingement in flexion than in other positions. CONCLUSION: Evaluation of the rheumatoid cervical spine is optimized using MR images in the neutral, flexed, and extended positions. Measurements and relationships between structures should be compared in all positions. CRs with flexion-extension views are recommended as the first imaging method.

Magnetic resonance imaging of microneurovascular free muscle flaps in facial reanimation.

The purpose of this study was to describe the survival and volume of microneurovascular muscle flaps at different times after two-stage facial reanimation procedure by using magnetic resonance imaging (MRI) and to compare the functional outcome with MRI findings. Fifteen patients with a mean age of 36 years (range 7-63 years) operated on between 1988 and 1999 were available for this study. The muscles used for functional reconstruction were the latissimus dorsi (eight patients), gracilis (six patients) and serratus anterior (one patient). Hospital charts were reviewed and the clinical outcome of facial reanimation was graded on a scale from 1 to 6 according to House. The mean postoperative follow-up time was 7 years (range 3-14 years). Clinical grading and 1.5 T unit MRI of patients were performed concomitantly. The MR images were evaluated semi-quantitatively so that the muscle structure of the free flaps was graded on a scale from 1 to 4. The free flap area of each slice was defined and the volume of the free flap was calculated. Data were analysed statistically. The long-term functional outcome of the facial reanimation was regarded as good in 10 patients, which means they had only mild or moderate dysfunction of facial movements. In MR images, six free flaps displayed normal muscle structure, another six had a fatty appearance and two displayed severe muscle atrophy; in one patient the muscle tissue could not be identified. The volume of the free flap clearly declined in the course of the follow-up. A correlation was found between good functional outcome and normal muscle structure of the free flap in MRI, p = 0.020. The longer the follow-up time after muscle transplantation the poorer the functional result. A similar correlation was found between abnormal muscle structure in MRI and a long follow-up time. Magnetic resonance imaging can be used to assess the muscle structure of free microneurovascular flaps. Normal findings in MRI seem to correlate with a good clinical outcome in facial reanimation. A good functional result correlates with a shorter follow-up time and normal muscle structure in MRI.

Acute knee trauma: analysis of multidetector computed tomography findings and comparison with conventional radiography.

PURPOSE: To evaluate the multidetector computed tomography (MDCT) findings of acute knee trauma and to compare radiography with MDCT in patients referred to a level 1 trauma center. MATERIAL AND METHODS: During a 5-year period, a total of 415 MDCT examinations were performed on 409 patients with acute knee trauma to reveal complex fracture anatomy or rule out a fracture. MDCT and primary radiographs were re-evaluated with respect to fracture location and trauma mechanism. Tibial plateau fractures were further analyzed depending on anatomical location: anterior-medial, anterior-lateral, posterior-lateral, and posterior-medial regions. Maximal depression of the tibial articular surface was measured. Findings on the primary knee radiographs were compared with MDCT findings. RESULTS: Of the 409 patients, 356 (87%) had a knee fracture. A total of 451 fractures were found in all anatomic regions: distal femur (n=49), proximal tibia (n=307), patella (n=23), and proximal fibula (n=72). Primary radiographs were available in 316 (76%) cases. Of these, 225 (71%) had MDCT in order to reveal the fracture anatomy better, and 91 (29%) had a subsequent MDCT after negative plain radiographs. Overall sensitivity of radiography was 83%, while negative predictive value was 49%. On radiography, tibial plateau articular depression was underestimated in all regions except when the fracture consisted of the whole half of the anterior or posterior plateau. The three main injury mechanisms were traffic accident, a simple fall, and sport. In 49 cases (15%), primary radiographs were suboptimal due to positioning. CONCLUSION: In severely injured patients, diagnostically sufficient radiographs are difficult to obtain, and therefore a negative radiograph is not reliable in ruling out a fracture. In these patients, MDCT is a fast and accurate examination and is also recommended in patients with tibial plateau fractures or complex knee injuries in order to evaluate the fracture adequately.

Multidetector computed tomography of cervical spine fractures in ankylosing spondylitis.

PURPOSE: To analyze multidetector computed tomography (MDCT) cervical spine findings in trauma patients with advanced ankylosing spondylitis (AS). MATERIAL AND METHODS: Using PACS, 2282 cervical spine MDCT examinations requested by emergency room physicians were found during a period of 3 years. Of these patients, 18 (16 M, aged 41-87, mean 57 years) had advanced AS. Primary imaging included radiography in 12 and MRI in 11 patients. RESULTS: MDCT detected one facet joint subluxation and 31 fractures in 17 patients: 14 transverse fractures, 8 spinous process fractures, 2 Jefferson's fractures, 1 type I and 2 type II odontoid process fractures, and 1 each: atlanto-occipital joint fracture and C2 laminar fracture plus isolated transverse process and facet joint fractures. Radiographs detected 48% and MRI 60% of the fractures. MRI detected all transverse and odontoid fractures, demonstrating spinal cord abnormalities in 72%. CONCLUSION: MDCT is superior to plain radiographs or MRI, showing significantly more injuries and yielding more information on fracture morphology. MRI is valuable, however, in evaluating the spinal cord and soft-tissue injuries. Fractures in advanced AS often show an abnormal orientation and are frequently associated with spinal cord injuries. In these patients, for any suspected cervical spine injuries, MDCT is therefore the imaging modality of choice.

Factors associated with nonunion in conservatively-treated type-II fractures of the odontoid process.

In type-II fractures of the odontoid process, the treatment is either conservative in a halo vest or primary surgical stabilisation. Since nonunion, requiring prolonged immobilisation or late surgery, is common in patients treated in a halo vest, the identification of those in whom this treatment is likely to fail is important. We reviewed the data of 69 patients with acute type-II fractures of the odontoid process treated in a halo vest. The mean follow-up was 12 months. Conservative treatment was successful, resulting in bony union in 32 (46%) patients. Anterior dislocation, gender and age were unrelated to nonunion. However, nonunion did correlate with a fracture gap (> 1 mm), posterior displacement (> 5 mm), delayed start of treatment (> 4 days) and posterior redisplacement (> 2 mm). We conclude that patients presenting with these risk factors are unlikely to achieve bony union by treatment in a halo vest. They deserve careful attention during the follow-up period and should also be considered as candidates for primary surgical stabilisation.

Multidetector computed tomography diagnosis of adult elbow fractures.

PURPOSE: To assess acute phase multidetector computed tomography (MDCT) findings in elbow traumas. MATERIAL AND METHODS: Fifty-six patients (32 M, 24 F, age 16 to 88 years, mean 44 years) underwent MDCT of the elbow due to an acute trauma during a time period of 34 months. RESULTS: A total of 65 fractures and 3 main fracture types were established: 16 (25%) ulnar coronoid process fractures, 13 (20%) radial head fractures, and 12 (18%) humeral supracondylar fractures. Three main injury mechanisms were falling (38 (68%) patients), falling from high places (6 (11%) patients), and traffic accidents (5 (9%) patients). In 6 (11%) patients, MDCT revealed 13 occult fractures in the elbow joint compared to primary radiography. In four (7%) patients a displaced fracture fragment was detected in primary radiography, but the origin of the fragment was unclear. In all four cases, MDCT revealed the origin of the fragment. CONCLUSION: Radiography remains the primary imaging modality in elbow trauma, but in complex fracture patterns, where the extent of the fractures and the position or origin of dislocated fragments is not clear by radiography, the MDCT is a recommended complementary examination.

Dynamic lateral patellar tilt in the anterior cruciate ligament-deficient knee. A magnetic resonance imaging analysis.

An open-configuration magnetic resonance imaging scanner was used to document patellar tracking abnormalities in 11 anterior cruciate ligament-injured knees. The contralateral normal knees were used as controls. Images were obtained with the quadriceps muscles at rest (knee flexion at 40 degrees, 25 degrees, and 10 degrees) and with the quadriceps muscles contracted (knee flexion at 40 degrees and 25 degrees). When the quadriceps muscles were at rest there were no differences in patellar alignment between the anterior cruciate ligament-injured knees and the contralateral normal knees. When the quadriceps muscles were maximally contracted at 40 degrees of flexion, the patellae of the anterior cruciate ligament-injured knees tilted laterally 3.6 degrees relative to the resting state. When the quadriceps muscles were contracted at 25 degrees of flexion, the patellae of the anterior cruciate ligament-injured knees tilted laterally approximately 4 degrees relative to the resting state. Quadriceps-active lateral patellar tilt at 25 degrees of flexion was greater in the anterior cruciate ligament-injured knees than in the contralateral normal knees, and it correlated with instrumented measurements of anterior tibial translation. Dynamic lateral patellar tilt during open kinetic chain exercises and during other activities that produce anterior tibial translation may contribute to extensor mechanism dysfunction in the anterior cruciate ligament-injured knee.

Interventional and intraoperative magnetic resonance imaging.

The goal of the Image Guided Therapy Program, as the name implies, is to develop the use of imaging to guide minimally invasive therapy. The program combines interventional and intraoperative magnetic resonance imaging (MRI) with high-performance computing and novel therapeutic devices. In clinical practice the multidisciplinary program provides for the investigation of a wide range of interventional and surgical procedures. The Signa SP 0.5 T superconducting MRI system (GE Medical Systems, Milwaukee, WI) has a 56-cm-wide vertical gap, allowing access to the patient and permitting the execution of interactive MRI-guided procedures. This system is integrated with an optical tracking system and utilizes flexible surface coils and MRI-compatible displays to facilitate procedures. Images are obtained with routine pulse sequences. Nearly real-time imaging, with fast gradient-recalled echo sequences, may be acquired at a rate of one image every 1.5 s with interactive image plane selection. Since 1994, more than 800 of these procedures, including various percutaneous procedures and open surgeries, have been successfully performed at Brigham and Women's Hospital (Boston, MA).

Kinematic magnetic resonance imaging of the upper cervical spine using a novel positioning device.

STUDY DESIGN: The development of a novel positioning device for magnetic resonance imaging of the upper cervical spine and an evaluation of motion patterns of the craniovertebral junction in asymptomatic volunteers as a part of the whole cervical spine motion. OBJECTIVES: To design and construct a positioning device that enables magnetic resonance imaging of the cervical spine in rotation, lateral bending, flexion, and extension in a horizontally open magnetic resonance scanner, and to define reference values for movements of the occiput (C0), the atlas (C1), and the axis (C2) in asymptomatic volunteers. SUMMARY OF BACKGROUND DATA: In previously used devices, the direction of motion is limited usually to flexion-extension, or the position of the head and neck are adjusted without a positioning device using semihard wedges or pillows. METHODS: Magnetic resonance imaging of the upper cervical spine in 20 asymptomatic individuals (10 men and 10 women) was performed in a horizontally open 0.23-T magnetic resonance imager in progressive steps during rotation, lateral bending, and flexion-extension using axial, coronal, and sagittal imaging planes, respectively. The positions of C0, C1, and C2 were measured, and pattern of motions between segments analyzed. Lateral displacement of the atlas during lateral bending and cranial migration distance during flexion-extension were assessed. RESULTS: The nonferromagnetic positioning device was designed and constructed. The motion patterns of the craniovertebral junction during rotation did not differ between the men and women, but in lateral bending there was a small difference between genders at C1-C2. In men, the position of C1 during flexion-extension was consistently more extended in relation to C0 and C2 than in women. CONCLUSIONS: The new positioning device allows magnetic resonance imaging of the upper cervical spine during flexion, extension, rotation, and lateral bending. To assess the relationship between C0-C1 and C1-C2 in flexion and extension, separate reference values for men and women are recommended.

Magnetic resonance imaging-guided focused ultrasound synovectomy.

OBJECTIVE: To investigate the feasibility of magnetic resonance imaging (MRI)-guided high power focused ultrasound (FUS) to perform synovectomy noninvasively. METHODS: Five New Zealand white male rabbit knees with experimentally induced arthritis underwent MRI-guided thermal surgery by high power (60 W/10 s) sonication. Evidence of tissue coagulation was monitored during the procedure and confirmed by gross and microscopic evaluation and MRI. RESULTS: Partial synovectomy was performed in five animals. Necrotized synovial tissue was observed on gross and microscopic evaluation. Visible signal intensity alterations including high signal intensity on T2-weighted (T2W) images and lack of contrast-enhancement on T1-weighted (T1W) post-contrast, post-sonication images were characteristic and reproducible. CONCLUSION: Our results demonstrate the ability of high power sonication to destroy synovial tissue in vivo.