Diane M. Deely

The septic versus nonseptic inflamed joint: MRI characteristics.

Abstract Objective. To differentiate the MR features of septic versus nonseptic inflamed joints. Design and patients. Thirty patients were referred for MRI with inflamed joints (19 were subsequently found to be septic and 11 nonseptic). At 1.5 T enhanced MRI five groups of signs related to joint space, synovium, cartilage, bone and peri-articular soft tissue respectively were assessed and compared between the septic and nonseptic groups. Results. The prevalence of MRI findings in septic versus nonseptic joints (respectively) was as follows: effusion (79% vs 82%), fluid outpouching (79% vs 73%), fluid heterogeneity (21% vs 27%), synovial thickening (68% vs 55%), synovial periedema (63% vs 55%), synovial enhancement (94% vs 88%), cartilage loss (53% vs 30%), bone erosions (79% vs 38%), bone erosions enhancement (77% vs 43%), bone marrow edema (74% vs 38%), bone marrow enhancement (67% vs 50%), soft tissue edema (63% vs 78%), soft tissue enhancement (67% vs 71%), periosteal edema (11% vs. 10%). The presence of bone erosions appeared to be an indicator for an infected joint (P=0.072); coexistence of bone marrow edema slightly improves the significance (0.068). A similar trend was obtained when combining bone erosions with either synovial thickening, synovial periedema, bone marrow enhancement or soft tissue edema (P=0.075). Conclusions. The combination of bone erosions with marrow edema is highly suggestive for a septic articulation; the additional coexistence of synovial thickening, synovial edema, soft tissue edema or bone marrow enhancement increases the above level of confidence. Similar to conventional radiography, the single sign that appeared to show a significant trend was the presence of bone erosions. However, no single sign or combination could either be considered pathognomonic or exclude the presence of a joint infection.

MR appearance of idiopathic synovial osteochondromatosis.

Objective A retrospective review of the MR examinations in 21 patients with idiopathic synovial osteochondromatosis (ISO) was performed to determine its MRI characteristics. Materials and Methods Twenty-one patients diagnosed with ISO had undergone MRI prior to surgery. The MR images were retrospectively evaluated for configuration and extent of lesion as well as for signal characteristics. Results Three distinct MR patterns were seen in ISO: A—lobulated homogeneous intraarticular signal isointense to slightly hyperintense to muscle on T1-weighted images and hyperintense on T2-weighted images (n = 3); B—pattern A plus foci of signal void on all pulse sequences (n = 17); and C—features of pattern A and B plus foci of peripheral low signal surrounding central fat-like signal (n = 2). The foci of signal void in pattern B and C corresponded to areas of calcification and the foci of peripheral low signal surrounding central fat-like signal in pattern C corresponded to areas of ossification. Conclusion The MR appearance of ISO appears sufficiently unique to allow its differentiation from other causes of intraarticular pathology.

Efficacy of magnetic resonance imaging in the evaluation of posterior cervical spine fractures.

STUDY DESIGN A retrospective study using two independent, blinded musculoskeletal radiologists to evaluate the sensitivity, specificity, and predictive value of cervical spine magnetic resonance imaging in detecting posterior element fractures of the cervical spine. OBJECTIVE To evaluate the sensitivity, specificity, and predictive value of magnetic resonance imaging, using computed tomographic scanning as the gold standard, in the diagnosis of posterior element cervical spine fractures. SUMMARY OF BACKGROUND DATA Few investigators have evaluated the accuracy of magnetic resonance imaging in the determination of cervical spine fractures. METHODS From January 1994 through June 1996, 75 cervical spine fractures in 32 patients were confirmed by computed tomography. Two musculoskeletal radiologists who were blinded to the clinical history and presence or absence of cervical injury among the study population, independently evaluated each cervical magnetic resonance image recording the presence or absence of soft tissue or bony injury. RESULTS The overall sensitivity and specificity rates for the diagnosis of a posterior element fracture by magnetic resonance imaging was 11.5% and 97.0%, respectively. The positive predictive value for this group was 83%, and the negative predictive value was 46%. In reference to anterior fractures, the sensitivity was 36.7% and the specificity 98%. Positive and negative predictive values were 91.2% and 64%, respectively. CONCLUSIONS Magnetic resonance imaging was not effective in recognizing bony injury to the cervical spine and in particular was not as sensitive or as specific as computed tomography in identifying cervical spinal fractures. Computed tomography remains the study of choice for the detection and precise classification of bony injuries to the cervical region, especially when plain radiographs are difficult to evaluate. Magnetic resonance imaging, although not as effective as computed tomography in defining specific bony disorders, remains the gold standard in the evaluation of spinal cord injury, occult vascular injury, and intervertebral disc disruption (hyperextension injury), including herniation and other soft tissue disorders (hematoma, ligament tear).

Helical CT of talar fractures

Since the degree of comminution, fracture alignment, and articular congruity of talar fractures are important determinants of treatment, we review the helical CT technique for detecting and assessing the extent of acute talar fractures. Helical CT can be used to classify talar neck fractures which often cannot be determined by radiography. It is also useful in detecting posterior process, lateral process, and avulsion fractures, as well as acute osteochondral fractures. Multiplanar CT using 1-mm acquisitions allows optimal evaluation, detects fractures initially missed on radiographs, and determines further extent of fractures.

POSTERIOR TIBIAL TENDON DYSFUNCTION : SECONDARY MR SIGNS

We evaluated four potential secondary magnetic resonance imaging signs to aid in clinical diagnosis of posterior tibial tendon (PTT) tears. Seventy-one ankles (25 PTT tears and 46 controls) were evaluated for the following secondary signs: (1) PTT sheath fluid, (2) a distal tibial spur located just anterior to the PTT, (3) unroofing of the talus, and (4) “bone bruise”-like medullary lesions. Two musculoskeletal radiologists rated their confidence using a scale and were compared for level of agreement. The presence of PTT sheath fluid had modest specificity and fair to moderate sensitivity. Tibial spurring and unroofing of the talus had excellent specificity and fair sensitivity. Bone bruise-like lesions were commonly seen in cases and controls. Examination of divergence of opinion between the two radiologists revealed pitfalls in interpretation of PTT sheath fluid and bone bruise-like lesions, which were commonly the result of adjacent vessels and inhomogeneous fat saturation, respectively. We conclude that secondary signs of PTT tears with high specificities include unroofing of the talus, tibial spurring, and PTT sheath fluid.

The effect of training and experience on the magnetic resonance imaging interpretation of meniscal tears

To evaluate the effects of experience and training in the magnetic resonance imaging (MRI) diagnosis of meniscal tears 30 consecutive patients (60 menisci) in whom MRI of the knee with arthroscopic confirmation of meniscal status were studied. MRIs were interpreted by 10 reviewers of varying levels of training and experience ranging from first-year radiology residents to attending musculoskeletal radiologists. Sensitivity and specificity, and intraobserver variability of MRI interpretation of meniscal tears were calculated for each reviewer and compared to those of readers of the same and varying levels of MRI training and experience. Accuracy (range, 78% to 88%), sensitivity (range, 79% to 88%), and specificity (range, 72% to 94%) results were high, and intraobserver agreement was moderate to high (range, 0.49 to 0.77), in the diagnosis of meniscal tears for all reviewers with 4 or more years of radiology residency training and 3 months of formal MRI experience. In contrast, the accuracy (range, 63% to 82%), sensitivity (range, 58% to 79%), and specificity (range, 58% to 72%) results of reviewers with less experience and training were lower, with higher intraobserver variability. Our results suggest that experience and training play an important role in the accurate and reliable MRI diagnosis of meniscal tears.

Helical CT of calcaneal fractures: technique and imaging features

Abstract Since the degree of comminution, fracture alignment, and articular congruity of intra-articular calcaneal fractures are important determinants in surgical treatment and patient prognosis, we review helical computed tomographic (CT) technique and features for detecting and assessing the extent of acute calcaneal fractures. Helical CT can be used to classify these fractures and facilitate the surgeon’s understanding of the anatomy and position of the fracture components in all orthogonal planes independently of the patient’s condition, foot placement in the CT gantry, or other injuries.

Prevalence and pattern of gluteus medius and minimus tendon pathology and muscle atrophy in older individuals using MRI

PurposeTo evaluate gluteus medius and minimus tendon pathology and muscle atrophy in older individuals using MRI.MethodsA retrospective MRI study of 185 individuals was performed. The inclusion criterion was age ≥50. Exclusion criteria were hip surgery, fracture, infection, tumor, or inadequate image quality. Greater trochanteric bursitis was graded none, mild, moderate, or severe. Gluteus medius, gluteus minimus, and iliopsoas tendinopathy was graded normal, tendinosis, low-grade partial tear, high-grade partial tear, or full thickness tear. Gluteus medius, gluteus minimus, tensor fascia lata, and iliopsoas muscle atrophy was scored using a standard scale. Insertion site of tendinopathy and location of muscle atrophy were assessed. Descriptive and statistical analysis was performed.ResultsThere was increasing greater trochanteric bursitis and gluteus medius and minimus tendinopathy and atrophy with advancing age with moderate to strong positive associations (p < 0.0001) for age and tendinopathy, age and atrophy, bursitis and tendinopathy, and tendinopathy and atrophy for the gluteus medius and minimus. There is a weak positive association (p < 0.0001) for age and tensor fascia lata atrophy, and no statistically significant association between age and tendinopathy or between age and atrophy for the iliopsoas. Fishers exact tests were statistically significant (p < 0.0001) for insertion site of tendon pathology and location of muscle atrophy for the gluteus medius.ConclusionsGluteus medius and minimus tendon pathology and muscle atrophy increase with advancing age with progression of tendinosis to low-grade tendon tears to high-grade tendon tears. There is an associated progression in atrophy of these muscles, which may be important in fall-related hip fractures.

Use of a novel percutaneous biopsy localization device: initial musculoskeletal experience

ObjectiveTo preliminarily evaluate a new CT-biopsy guidance device, the SeeStar (Radi, Uppsala, Sweden), for use in musculoskeletal applications.DesignThe device was evaluated using an imaging phantom and in various simulated clinical biopsy situations. The phantom study was undertaken to optimize the linear metallic artifacts produced by the guidance device. The phantom and guidance device were imaged with CT after altering different imaging parameters, including field of view, filter, focal spot size, kV, mAs, slice thickness and pitch. Clinical biopsy situations were simulated for a superficial biopsy, a deep biopsy and a horizontal biopsy approach.ResultsAltering CT parameters had little effect on the subjective appearance of the linear metal artifact, which is used to plan the biopsy approach. Placement of an 18-G needle inside of the biopsy device was subjectively helpful in exaggerating the artifact. Use of this artifact could be helpful in planning biopsy approach for deep lesions or lesions near critical structures. The metal guide on the device adequately supports a standard biopsy needle, making it potentially advantageous for biopsy of superficial lesions and lesions approached from a horizontal orientation.ConclusionUse of this CT-biopsy guidance device is potentially useful for musculoskeletal applications. The linear metal artifact produced by the device can help plan the biopsy approach. The device can also be useful in biopsy situations where the biopsy needle requires external support during imaging.

CT-guided Cervical Bone Biopsy in 43 Patients: Diagnostic Yield and Safety at Two Large Tertiary Care Hospitals

RATIONALE AND OBJECTIVES The cervical spine is a high-risk area for percutaneous biopsy compared to the thoracic and lumbar regions. Biopsy of the cervical spine is less commonly undertaken, and previously published series on diagnostic yield and safety of cervical spine biopsy have been limited to 12 patients or less. The purpose of our study is to further define the diagnostic yield of computed tomography (CT)-guided biopsy for bony lesions identified in the cervical spine, by combining data from two large tertiary care referral centers. METHODS A retrospective review of an imaging database was performed to identify all percutaneous CT-guided biopsies of the cervical spine performed at two tertiary care hospitals from 2010 to 2015. Core biopsies were obtained whenever possible and supplemented with fine-needle aspiration in some cases. Histopathologic results of the biopsy were recorded, as were changes in subsequent management, need for repeat biopsy, and complications. RESULTS Forty-three patients underwent CT-guided biopsy of the cervical spine. Sufficient tissue for histopathologic analysis was obtained in 41 out of 43 cases, for a yield of 95%. One case was false-negative and one was deemed insufficient by the pathologist for diagnostic purposes; in both of these cases, only a fine-needle aspiration was obtained. There were no immediate or delayed complications. CONCLUSIONS Percutaneous biopsy of the cervical spine is a safe and high-yield method of obtaining a tissue diagnosis when performed under image guidance with CT.