High risk of tunnel convergence during combined anterior cruciate ligament and anterolateral ligament reconstruction.

PURPOSE: To assess the risk of femoral tunnel convergence in combined anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstructions. The hypothesis was that a more proximal and anterior orientation of the ALL femoral tunnel should reduce the risk of convergence with the ACL femoral tunnel. METHODS: 15 fresh-frozen cadaver knees were examined. An anatomic ACL femoral tunnel was drilled arthroscopically in each specimen and ALL tunnels were made in two directions: (1) 0° coronal angulation and 20° axial angulation, (2) 30° coronal angulation and 30° axial angulation. Computed tomography scans were performed to investigate tunnel convergence and to measure the minimal distance between tunnels, tunnel length and the LFC width. RESULTS: Tunnel convergence occurred in 20 of 30 cases (67%). Convergence was significantly reduced when tunnels were drilled at 30° coronal and 30° axial angulation (p < 0.05). The mean length of the ALL tunnel was 15.9 mm [95% CI (13.6; 18.1)] and was independent of ALL tunnel angulation. The mean minimal distance between the ALL and ACL tunnel was 3.1 mm [95% CI (2.1; 4.1)]. The odds ratio for tunnel convergence was 3.5 for small LFC, relative to large LFC (n.s.) CONCLUSION: A high risk of tunnel convergence was observed when performing combined ACL and ALL reconstructions. The clinical relevance of this work is that the occurrence of tunnel conflicts can be reduced by aiming the ALL tunnel in a more proximal and anterior direction. Surgeons should be aware of this, since tunnel convergence could jeopardize the ACL reconstruction and fixation.

Carpal boss syndrome.

Carpal boss is a bony prominence located dorsally on the base of the second and/or third CMC joint. We describe the imaging findings of the pathology in two patients and the relative contributive role of the different modalities and stress the decisive role of MRI.

Peripheral neuropathy caused by joint-related cysts: a review of 17 cases.

BACKGROUND: Clinical compression neuropathy caused by para-articular cysts is rare. Only recently, the unifying articular theory was proposed to clarify its true etiologic nature. The authors attribute 17 cases to this theory in order to illustrate the shift in the diagnostic and treatment protocol, and the possible impact on patient outcome. METHODS: Eight intraneural and nine extraneural cysts were included. The proposed diagnostic protocol includes electromyography and ultrasound, followed by magnetic resonance imaging to characterize the cyst. The proposed treatment protocol consists of (1) ligation of the pedicle connecting the cyst with the afflicted joint, (2) decompression of the nerve and, when needed and (3) disarticulation of the superior tibiofibular joint (in case of peroneal nerve involvement). RESULTS: Outcome was good to excellent in all patients, with recovery of sensory and motor function. Cyst recurrence was observed in three intraneural cases (18 %). Analysis of our own diagnostic protocol showed that atypical compression neuropathies should follow a strict diagnostic protocol to exclude missing the presence of a cyst. Ultrasound needs to play a crucial role, with MRI for cyst characterization and pedicle identification. CONCLUSIONS: Retrospective proof in favor of the articular theory was found in all cases. An explanation for the cyst recurrences was formed based on the articular theory. In addition, a diagnostic and therapeutic protocol is proposed for all atypical peripheral compression neuropathies with the ultimate goal to achieve optimal patient outcome.

Trevor's disease and whole-body MRI.

Dysplasia epiphysealis hemimelica (DEH), also known as Trevor's disease, is a rare disease characterized by osteocartilaginous overgrowth involving single or multiple epiphyses on the medial or the lateral side of an affected limb. DEH usually becomes clinically evident in childhood. Imaging has a major role in the diagnosis of DEH. Typical location and radiographical features, together with a distinct distribution usually permit diagnosis. Magnetic resonance imaging (MRI) is often used as an additional imaging modality to evaluate the lesion. Whole-body MR imaging (WBMRI) currently has become a relatively fast imaging method having good sensitivity to detect lesions in the larger bones of the skeleton. In Trevor's disease, WBMRI can demonstrate (clinically and radiographically unsuspected) additional lesions throughout the affected limb without use of ionizing radiation, revealing the typical distribution pattern of DEH. We propose to add WBMRI to the routine MRI examination performed to evaluate the lesion itself. WBMRI may have a clear therapeutic advantage: if a distribution pattern typical of DEH is found, it constitutes a strong argument in favor of Trevor's disease which may avoid the need to perform biopsy.

Clinical feasibility of a magnetic resonance tracking system to guide the position of the scan plane during physiologic joint motion.

PURPOSE: Unrestricted physiologic joint motion results in multidirectional displacement of the anatomic structures. When performing real-time magnetic resonance (MR) imaging of such a joint motion, continuous adjustment of the scan plane position may be required. The purpose of this study was to evaluate the clinical feasibility of a method to guide the scan plane position during dynamic-motion MR imaging of freely moving joints. MATERIALS AND METHODS: The location of a small tracker device (dedicated hardware) placed on the patient's skin overlying a joint was determined by an ultrashort MR sequence and used to automatically adjust the scan plane position prior to each dynamic-motion MR image. Using a vertically open MR unit, this MR tracking system was applied in ten dynamic-motion MR examinations to evaluate flexion/extension manoeuvres in the weight-bearing knee joint, and in ten dynamic-motion MR examinations of the shoulder joint to evaluate manoeuvres such as internal/external rotation of the humerus, stress testing of the glenohumeral joint and abduction/adduction manoeuvres. Average number of manoeuvre repetitions, total number of images and percentage of useful images per manoeuvre were calculated. Imaging time per scan plane for each manoeuvre was recorded. RESULTS: Average repetition of manoeuvres varied between 1.6 and 5.8, with an average number of 7 to 18 images per manoeuvre. Average percentage of useful images varied between 61% and 89%. Total imaging time per scan plane ranged between 1 min 10 s and 4 min 51 s. CONCLUSIONS: The MR tracking system to guide the slice position for each consecutive dynamic-motion MR image of the freely but slowly moving shoulder or knee joint was feasible for clinical use, providing a high percentage of useful images for each manoeuvre within a clinically acceptable time frame.

Magnetic resonance imaging-guided closed reduction treatment for developmental dysplasia of the hip.

INTRODUCTION: This study aimed to describe the radiological aspects and procedural steps of magnetic resonance (MR) imaging-guided closed reduction for the treatment of developmental dysplasia of the hip (DDH). METHODS: Infants were positioned on a custom-made hip spica table attached to a vertically open double doughnut-shaped MR imaging unit (GE Signa SP, 0.5T) affording access to one orthopaedic surgeon and one radiologist. Standard MR imaging sequences and rapid dynamic MR imaging sequences, including fast spin-echo, fast gradient-echo and a fluoroscopic echo-planar sequence, were available. Procedural steps were described and illustrated as a guide for the radiologist actively collaborating with the orthopaedic surgeon. RESULTS: Five separate procedural steps were defined, describing the imaging action and the radiologist's focus related to the clinical action. These procedural steps included patient positioning, static imaging to evaluate hip congruency and factors impeding reduction, dynamic stress testing and reducing the hip while using dynamic motion MR imaging sequences to visualise reduction or dislocation, cast application with intermittent imaging confirmation of the femoral head position, and postprocedural static imaging. CONCLUSION: The role of the radiologist was well-defined during each procedural step of the MR imaging-guided closed reduction focusing on the use of specific sequences and image interpretation. Knowledge of these procedural steps may be helpful for efficient collaboration with the orthopaedic surgeon and successful MR imaging-guided treatment of DDH.

All-in-one magnetic resonance arthrography of the shoulder in a vertically open magnetic resonance unit.

BACKGROUND: Magnetic resonance (MR) arthrography frequently involves joint injection under imaging guidance followed by MR imaging in static positions. PURPOSE: To evaluate if MR arthrography of the shoulder joint can be performed in a comprehensive fashion combining the MR-guided injection procedure, static MR imaging, and dynamic motion MR imaging in a single test. MATERIAL AND METHODS: Twenty-three shoulder joints were injected with Gd-DTPA2- under MR guidance. Static MR imaging was performed and included a three-point Dixon method to achieve water-selective images. Dynamic motion MR imaging with and without applying pressure to the upper arm was used to evaluate glenohumeral joint instability. In 10 cases, surgical correlation was available. RESULTS: The all-in-one MR arthrography technique was successful in all patients, and took an average time of 65 min. All but one glenohumeral injection procedure were performed with a single needle pass, and no complications were observed. Out of eight labrum tears seen with static MR imaging, seven were confirmed at surgery. In 10 cases, dynamic motion MR imaging correlated well with the surgeon's intraoperative evaluation for presence and direction of instability. CONCLUSION: MR arthrography of the shoulder joint using a vertically open magnet can be performed as a single comprehensive test, including the injection and the static and dynamic motion MR imaging. Good diagnostic accuracy for intraarticular lesions and glenohumeral instability was found in a small sample.

Reduction of metal artefacts in musculoskeletal MR imaging.

The purpose of this article is to present a educational overview of practical tips to deal with metal artefacts in clinical musculoskeletal MRI. A brief theoretical explanation to understand the cause of metal artefacts is provided followed by a discussion on parameters to reduce these metal artefacts. Effects of adjustable parameters are demonstrated both in a volunteer with a titanium screw and a saline bag attached to the shoulder and in a in vitro experiment. These parameters include positioning of the patient with the long axis of metallic hardware parallel to B0, use of fast spin echo sequences, use of inversion recovery fat suppression, swapping phase and frequency encoding direction, use of view angle tilting, increasing the read-out bandwidth, and decreasing voxel size.

Functional magnetic resonance imaging for preoperative localisation of eloquent brain areas relative to brain tumours: clinical implementation in a regional hospital.

The purpose of this study was to evaluate the implementation of functional magnetic resonance imaging (fMRI) for clinical use in patients with a brain tumour in the setting of a regional hospital. Twenty-three patients underwent a fMRI examination as preoperative evaluation for a tumour adjacent to a eloquent brain area. The location and distance of the tumour relative to the fMRI activation area for this eloquent brain area was determined. Presence of postoperative neurological deficits was compared to the result of the fMRI examination. The fMRI examination was not interpretable in four of the twenty-three patients. In nine patients the eloquent brain area was located more than two centimetres from the tumour: seven showed no neurological deficit postoperatively, one patient experienced a temporary deficit, and one patient has not been operated yet. In the remaining ten patients the eloquent brain area was located less than two centimetres from the tumour: after (partial) resection of the tumour often using intra-operative cortical stimulation, six patients showed no neurological deficits, and three patients had temporary or permanent deficits. One patient was not operated. The clinical implementation of fMRI was successful in the preoperative evaluation of patients with a brain tumour and useful to plan the surgical intervention and to minimize postoperative neurological deficits.

Lymphadenopathy at the medial epitrochlear region in cat-scratch disease.

Our objective was to describe the imaging features of lymphadenopathy at the medial epitrochlear region as frequently seen in cat-scratch disease (CSD) and to compare these features with those seen in non-CSD. Ten patients (four males and six females) presented with a subcutaneous soft tissue mass at the medial epitrochlear region. Three patients were younger than 15 years. Magnetic resonance imaging was performed in all patients. All lesions turned out to be regional lymphadenopathy instead of soft tissue neoplasm. They were caused by benign disorders in eight cases, including seven CSD and one other infection, and in two cases by metastatic disease. All lesions, except for three benign ones, were solitary. On MRI, high signal intensity (SI) strands in the surrounding soft tissue on T2-weighted images (WI) were present in all cases. Three cases of CSD showed homogeneous SI on both T1- and T2WI. After contrast administration, a moderate, homogeneous enhancement was seen. The other seven lesions, except for one metastasis, had both solid and liquid components. Liquid components showed high SI on T2WI without enhancement, whereas solid components had intermediate SI on T2WI and marked enhancement after contrast administration. Pathological findings in seven patients, including four with CSD, supported the tentative diagnosis made on MRI. One of two patients with CSD had positive serological test. Cat-scratch disease is a major cause of a soft tissue swelling at the medial epitrochlear region. Identification of lymphadenopathy and its presentation on MRI may be helpful in eliciting an animal-scratch history and achieving diagnostic and therapeutic aims in patients without primary cancer.