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Objective: The purpose of this study was to assess if ultra-low-dose CT is a useful clinical alternative to digital radiographs in the evaluation of acute wrist and ankle fractures., Materials and Methods: An ultra-low-dose protocol was designed on a 256-slice multi-detector CT. Patients from the emergency department were evaluated prospectively. After initial digital radiographs, an ultra-low-dose CT was performed. Two readers independently analyzed the images. Also, the radiation dose, examination time, and time to preliminary report was compared between digital radiographs and CT., Results: In 207 extremities, digital radiography and ultra-low-dose CT detected 73 and 109 fractures, respectively (p < 0.001). The odds ratio for fracture detection with ultra-low-dose CT vs. digital radiography was 2.0 (95% CI, 1.4-3.0). CT detected additional fracture-related findings in 33 cases (15.9%) and confirmed or ruled out suspected fractures in 19 cases (9.2%). The mean effective dose was comparable between ultra-low-dose CT and digital radiography (0.59 ± 0.33 μSv, 95% CI 0.47-0.59 vs. 0.53 ± 0.43 μSv, 95% CI 0.54-0.64). The mean combined examination time plus time to preliminary report was shorter for ultra-low-dose CT compared to digital radiography (7.6 ± 2.5 min, 95% CI 7.1-8.1 vs. 9.8 ± 4.7 min, 95% CI 8.8-10.7) (p = 0.002). The recommended treatment changed in 34 (16.4%) extremities., Conclusions: Ultra-low-dose CT is a useful alternative to digital radiography for imaging the peripheral skeleton in the acute setting as it detects significantly more fractures and provides additional clinically important information, at a comparable radiation dose. It also provides faster combined examination and reporting times.

Objective: The aims of this work are to determine how frequently medial tibial plateau fractures are accompanied by fibular head avulsion fractures and evaluate the sensitivity of radiographs detecting them, and also to assess if the presence of fibular fracture is correlated with long-term functional outcome and peroneal nerve damage., Materials and Methods: A retrospective chart review of operated patients with medial tibial plateau fractures at level I trauma center during 2002-2008 was performed. From 63 patients imaged preoperatively, 59 had CT and radiographs, three had only CT, and one only radiograph. The presence and fragment size of fibular fracture were retrospectively evaluated. Body mass index (BMI) and functional outcome measurements (the Modified Lysholm knee score and WOMAC) were available for 46 patients., Results: Fourteen out of 63 patients (22.2%) had fibular fractures. Of the 59 patients with both CT and radiographs, 12 had fibular fractures, and of these, nine were seen with both modalities and three only in CT. Functional scores were available for ten patients with fibular fracture. Patients with fibular fracture seen on radiographs had a significantly higher score on WOMAC function (26 vs. 7; p = 0.027). The patients with fibular fractures had also higher BMI (p = 0.035). Of the six patients with peroneal nerve damage, 50% had fibular fracture., Conclusions: In patients with operatively treated medial tibial plateau fracture, the fibular fractures are relatively common. Detecting it is important, as it may be associated with worse functional scores and peroneal nerve paresis. Some fibular fractures may remain undetected on radiographs, hence preoperative CT is recommended.

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.

Objective: To examine dual-energy computed tomography (DECT) in evaluating cruciate ligament injuries. More specifically, the purpose was to assess the optimal keV level in DECT gemstone spectral imaging (GSI) images and to examine the usefulness of collagen-specific color mapping and dual-energy bone removal in the evaluation of cruciate ligaments and the popliteus tendon., Materials and Methods: At a level 1 trauma center, a 29-month period of emergency department DECT examinations for acute knee trauma was reviewed by two radiologists for presence of cruciate ligament injuries, visualization of the popliteus tendon and the optimal keV level in GSI images. Three different evaluating protocols (GSI, bone removal and collagen-specific color mapping) were rated. Subsequent MRI served as a reference standard for intraarticular injuries., Results: A total of 18 patients who had an acute knee trauma, DECT and MRI were found. On MRI, six patients had an ACL rupture. DECT's sensitivity and specificity to detect ACL rupture were 79% and 100%, respectively. The DECT vs. MRI intra- and interobserver proportions of agreement for ACL rupture were excellent or good (kappa values 0.72-0.87). Only one patient had a PCL rupture. In GSI images, the optimal keV level was 63 keV. GSI of 40-140 keV was considered to be the best evaluation protocol in the majority of cases., Conclusion: DECT is a usable method to evaluate ACL in acute knee trauma patients with rather good sensitivity and high specificity. GSI is generally a better evaluation protocol than bone removal or collagen-specific color mapping in the evaluation of cruciate ligaments and popliteus tendon.

Objective: To assess the number and anatomical location of fractures associated with elbow dislocation, to study the correlation between the direction of dislocation and the trauma energy, and to assess radiographs' diagnostic performance characteristics for fractures using MDCT as a reference standard., Materials and Methods: A retrospective study was performed at a level 1 trauma center, finding a total of 140 patients who had sustained an elbow dislocation and who had undergone a subsequent MDCT examination. The CT and radiographs of the patient were reviewed by two musculoskeletal radiologists. CT images were analyzed for the site and size of the fracture fragments. In addition, the primary direction of the dislocation, patients' age, and gender were recorded. Trauma energy was also assessed., Results: One hundred and thirty-four out of 140 patients (96%) had a fracture that was seen on the correlative CT examination. The most common anatomical fracture locations were the coronoid process of the ulna 84 out of 140 (60%), the radial head 75 out of 140 (54%), and the humeral capitellum 57 out of 140 (41%). Multiple fractures were seen in 71 out of 134 (53%) patients with fractures. The left elbow was more commonly dislocated than the right one. The overall sensitivity of the radiographs was 62% and the specificity 96%., Conclusion: Small fractures and impaction fractures are almost invariably present in elbow dislocations, and half of the patients have more than one fracture. Radiographs have a sensitivity of only 62%. MDCT is an invaluable method for determining the extent of bony injury and revealing occult fractures.

Purpose: To evaluate the feasibility and intra- and interobserver agreement of CBCT arthrography of wrist ligaments, triangular fibrocartilaginous complex (TFCC), and to assess the sensitivity (SE), specificity (SP), accuracy (ACC), and positive and negative predictive value (PPV, NPV) of CBCT arthrography in the diagnosis of scapholunate (SLL) and lunotriquetral (LTL) ligament tears, TFCC, and cartilage abnormalities of the scaphoid and lunate with their corresponding radial surfaces (scaphoid and lunate fossa) using a novel, mobile, dedicated extremity CBCT scanner., Materials and Methods: Fifty-two consecutively enrolled subjects (26 M, 26 F, mean age 38 years, range 18-66 years) with suspected wrist ligament tears underwent CBCT-arthrography before normally scheduled MR arthrography.An extremity CBCT was used for imaging with isotropic voxel size of 0.4 × 0.4 × 0.4 mm(3). Subsequent routine 1.5 T MRI was performed using a dedicated wrist coil.Two observers reviewed the anonymized CBCT images twice for contrast enhancement (CE) and technical details (TD), for tears of the SLL, LTL, and TFCC. Also, cartilage abnormalities of the scaphoid and lunate with their corresponding radial surfaces (scaphoid and lunate fossa) were evaluated. Inter- and intraobserver agreement was determined using weighted kappa statistics. Since no surgery was performed, MRI served as a reference standard, and SE and SP, ACC, PPV, and NPV were calculated., Results: Intra- and interobserver kappa values for both readers (reader 1/reader 2; first reading/second reading) with 95 % confidence limits were: CE 0.54 (0.08-1.00)/ 0.75 (0.46-1.00); 0.73 (0.29-1.00)/ 0.45 (0.07-0.83), TD 0.53 (0.30-0.88)/ 0.86 (0.60-1.00); 0.56 (0.22-0.91)/ 0.67 (0.37-0.98), SLL 0.59 (0.25-0.93)/ 0.66 (0.42-0.91); 0.31 (0.06-0.56)/ 0.49 (0.26-0.73), LTL 0.83 (0.66-1.00)/ 0.68 (0.46-0.91); 0.90 (0.79-1.00)/ 0.48 (0.22-0.74); TFCC (0.72-1.00)/ (0.79-1.00); 0.65 (0.43-0.87)/ 0.59 (0.35-0.83), radius (scaphoid fossa) 0.45 (0.12-0.77)/ 0.64 (0.31-0.96); 0.58 (0.19-0.96)/ 0.38 (0.09-0.66), scaphoid 0.43 (0.12-0.74)/ 0.76 (0.55-0.96); 0.37 (0.00-0.75)/ 0.32 (0.04-0.59), radius (lunate fossa) 0.68 (0.36-1.00)/ 0.42 (0.00-0.86); 0.62 (0.29-0.96)/ 0.51 (0.12-0.91), and lunate 0.53 (0.16-0.90)/ 0.68 (0.44-0.91); 0.59 (0.29-0.88)/ 0.42 (0.00-0.84), respectively. The overall mean accuracy was 82-92 % and specificity was 81-94 %. Sensitivity for LTL and TFCC tears was 76-83, but for SLL tears it was 58 %. For cartilage abnormalities, the accuracy and negative predictive value were high, 90-98 %., Conclusions: A dedicated CBCT extremity scanner is a new method for evaluating the wrist ligaments and radiocarpal cartilage. The method has an overall accuracy of 82-86 % and specificity 81-91 %. For cartilage abnormalities, the accuracy and negative predictive value were high.

Objective: To assess the reliability of measurements of spinal canal narrowing, vertebral body compression, and interpedicular widening in burst fractures in radiography compared with multidetector computed tomography (MDCT)., Materials and Methods: Patients who had confirmed acute vertebral burst fractures over an interval of 34 months underwent both MDCT and radiography. Measurements of spinal canal narrowing, vertebral body compression, and interpedicular widening from MDCT and radiography were compared., Results: The 108 patients (30 female, 78 male, aged 16-79 years, mean 39 years) had 121 burst fractures. Eleven patients had multiple fractures, of which seven were not contiguous. Measurements showed a strong positive correlation between radiography and MDCT (Spearman's rank sum test: spinal canal narrowing k = 0.50-0.82, vertebral compression k = 0.55-0.72, and interpedicular widening k = 0.81-0.91, all P < 0.05), except for the cervical spine (k = -0.50 to 0.61, with all P > 0.25) and for interpedicular widening in the thoracic spine (k = 0.35, P = 0.115). The average difference in measurements between the modalities was 3 mm or fewer., Conclusion: Radiography demonstrates interpedicular widening, spinal canal narrowing and vertebral compression with acceptable precision, with the exception of those of the cervical spine.

Objective: The objective was to study characteristic MRI findings in cervical spine fractures complicating ankylosing spondylitis (AS). Technical issues related to MRI are also addressed., Materials and Methods: A review of 6,774 consecutive cervical spine multidetector CT (MDCT) scans obtained during 6.2 years revealed 33 ankylosed spines studied for suspected acute cervical spine injury complicating AS. Of these, 20 patients also underwent MRI., Results: On MRI, of these 20 patients, 19 had a total of 29 cervical and upper thoracic spine fractures. Of 20 transverse fractures traversing both anterior and posterior columns, 7 were transdiskal and exhibited less bone marrow edema than did those traversing vertebral bodies. One Jefferson's, 1 atlas posterior arch (Jefferson's on MDCT), 2 odontoid process, and 5 non-contiguous spinous process fractures were detectable. MRI showed 2 fractures that were undetected by MDCT, and conversely, MDCT detected 6 fractures not seen on MRI; 16 patients had spinal cord findings ranging from impingement and contusion to complete transection., Conclusion: Magnetic resonance imaging can visualize unstable fractures of the cervical and upper thoracic spine. Paravertebral hemorrhages and any ligamentous injuries should alert radiologists to seek transverse fractures. Multiple fractures are common and often complicated by spinal cord injuries. Diagnostic images can be obtained with a flexible multipurpose coil if the use of standard spine array coil is impossible due to a rigid collar or excessive kyphosis.

Objective: To analyze with conventional magnetic resonance imaging (MRI) the signal appearance of menisci repaired with bioabsorbable arrows., Design and Patients: Forty-four patients with 47 meniscal tears treated with bioabsorbable arrows underwent follow-up conventional MRI examination. The time interval between the surgery and MRI varied from 5 to 67 months (mean 26 months). Twenty-six patients also had concurrent repair of torn anterior cruciate ligament. The following grades were used to classify meniscal signal intensity: (a) G0; low signal intensity on all sequences and regular configuration in every plane, (b) G1; increased signal intensity within the meniscus, not extending to the meniscal surface, (c) G2; increased signal intensity linear in shape, which may or may not communicate with the capsular margin of the meniscus, without extending to the meniscal surface, and (d) G3; increased signal intensity extending to the meniscal surface., Results: Thirteen menisci (27.5%) had normal signal intensity, 13 menisci (27.5%) Grade 1 signal intensity, 9 menisci (19%) Grade 2 signal intensity and 12 menisci (26%) Grade 3 signal intensity. The time difference between operation and MRI was statistically significant between the G0 (36 months) and G3 groups (14 months; P = 0.0288). There was no statistical significance in different grades between medial and lateral meniscus or between patients with operated or intact ACL. On physical examination sixteen patients reported slight symptoms, seen evenly in each group., Conclusion: No difference was seen in different grades between patients with operated or intact ACL. The highest incidence of menisci with a Grade 3 signal was seen in patients where surgery was within the last 18 months.

Clinical symptoms of hyperparathyroidism are generally nausea, vomiting, fatigue, constipation, and hypotonicity of the muscles and ligaments; bone pain and tenderness are also seen but are more common in secondary hyperparathyroidism. We report a histologically confirmed case of a 28-year-old man whose sole symptom of primary hyperparathyroidism was lower extremity radicular pain due to a vertebral brown tumor. Magnetic resonance imaging demonstrated brown tumor to be hyperintense on T2-weighted and slightly hypointense on T1-weighted sequences; it showed intense contrast enhancement with gadolinium. Because brown tumors usually contain hemosiderin a short T2 should have been expected, but this was not seen in our case. Healing resulted in decreasing contrast enhancement on T1-weighted sequences and increasingly short T2. To our knowledge, this is the first report of a lumbar vertebral brown tumor associated with primary hyperparathyroidism.

The recently introduced horizontally open configuration imagers allow imaging of knee, hip or shoulder during whole range of motion, which is not possible in conventional MR imagers. Special joint motion devices can be used to provide accurate and reproducible studies. In cervical spine, functional MR imaging may be useful in evaluating alarligament stability in patients with late sequelae of a whiplash injury, and in patients with rheumatoid arthritis who are clinically suspected of having a cervical myelopathy or superior migration of the odontoid process. In shoulder, full range of motion abduction study may be helpful in assessing the supraspinatus tendon impingement. To evaluate patellofemoral malalignment, quadriceps loading is recommended since associated contracting muscles and related soft tissue structures can be evaluated. The position of the femoral head relative to the acetabulum during different positions can be assessed. Open-configuration scanners provide an access to patients during scanning procedure, and therefore permit interventional procedures to be monitored with MRI. Such interventions include aspiration cytology/biopsy and different drainage procedures.

Purpose: To develop a superconducting magnetic resonance (MR) imager that provides direct access to the patient and permits interactive MR-guided interventional procedures., Materials and Methods: A 0.5-T superconducting magnet that allows a region of vertical access to the patient was designed and constructed. This magnet was integrated with newly designed shielded gradient coils, flexible surface coils, nonmagnetic displays, position-monitoring probes and device-tracking instrumentation., Results: The magnet homogeneity was 12.3 ppm or better, and the gradient field was linear to within 1% over an imaging region of 30 cm in diameter. The signal-to-noise ratio was 10% higher than in a comparable 0.5-T superconducting imager. Images were obtained in several anatomic regions with use of routine pulse sequences. Interactive image plane selection and near real-time imaging, with use of fast gradient-recalled echo sequences were demonstrated at a rate of one image every 1.5 s. More than 240 procedures (including open brain surgery) have been successfully performed within this environment., Conclusions: MR-guided interventional and surgical procedures can be performed with full patient access using an open-configuration, superconducting MR magnet with near real-time imaging and interactive image plane control.

Patellofemoral relationships were analyzed in 11 patients (13 knees) with patellar dislocation and 15 asymptomatic subjects (15 knees) at 0 degree and 20 degrees of flexion. The measurements were made from five consecutive axial images through the patellofemoral joint. The six indices measured were lateral patellar tilt (LPT), lateral patellofemoral angle (LPA), lateral patellar displacement (LPD), patella-lateral condyle index (L/PW), congruence angle (CA), and sulcus angle (SA). The reproducibility of the method was evaluated. The difference between the two study groups was more evident at 0 degree than at 20 degrees of knee flexion. Significant differences were noted between measurements made at different levels of the joint, particularly in the controls. Isometric contraction of the quadriceps muscle lateralized and tilted the patella slightly in both groups. L/PW with and without quadriceps muscle contraction, and LPA with reference to the anterior condyles differentiated between the two study groups most clearly. LPT and LPA with reference to the anterior condyles differentiated the study groups better than LPT and LPA with reference to the posterior condyles. The reproducibility was good except for inter-observer comparison of CA and SA. The use of an imaging plane selected at the midpoint of the patellar articular cartilage increases the sensitivity of the measurements, since it takes into account both the height of the patella and the tendency towards lateralization. These results indicate that patellar tilt is best measured with the LPA index and patellar lateralization with the L/PW index at 0 degree knee flexion. This study should always include isometric contraction of the quadriceps muscle.

Twenty patients with a chronic anterior cruciate ligament tear were studied. First they were interviewed on the preoperative history of unexpected giving way (pivot shift), then they were tested for clinical pivot shift sign, and last, the configuration of the lateral tibial plateau was studied using magnetic resonance imaging. A connection could be noticed between the history of instability symptoms and the pivot shift sign at clinical examination (P less than 0.001). Interestingly, there was also a link between the instability history and the configuration of the lateral tibial plateau (P = 0.0021), and, further, between the clinical pivot shift sign and the configuration of the lateral tibial plateau (P = 0.0002). The variation in the shape of the convexity of the lateral tibial plateau seems to be associated with the symptoms and prognosis of the patients with rupture of the anterior cruciate ligament.

Twelve knees in eleven patients with subluxation or dislocation of the patella were assessed by MRI at 0, 10, 20 and 30 degrees of knee flexion, before and after vastus lateralis release and medial transplant of the tibial tuberosity. The preoperative position of the patella deviated the greatest from normal in 0-20 degrees of knee flexion. The operations were found to correct the lateral patellofemoral angle and the lateral patella tilt with or without quadriceps muscle contraction, but did not completely correct the marked preoperative lateral patellar displacement and tracking.