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

OBJECTIVE: To preliminarily evaluate a new CT-biopsy guidance device, the SeeStar (Radi, Uppsala, Sweden), for use in musculoskeletal applications. DESIGN: The 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. RESULTS: Altering 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. CONCLUSION: Use 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.

Helical CT of calcaneal fractures: technique and imaging features.

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.

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 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.

MR imaging of bone marrow disorders.

This article discusses the MR imaging findings in osteomyelitis and septic arthritis. Criteria for differentiation of osteomyelitis from diabetic neuroarthropathy are presented. The article also presents an overview of MR imaging of avascular necrosis and criteria to differentiate transient osteoporosis from the edema pattern of avascular necrosis.

Ulcer osteoma and periosteal reactions to chronic leg ulcers.

OBJECTIVE: The purpose of this study was to describe the types of periosteal reaction seen in response to long-standing leg ulcers and to differentiate the types associated with osteomyelitis. MATERIALS AND METHODS: Over a 10-year span, we retrospectively evaluated the radiographs of 20 patients with lower leg soft-tissue ulceration and adjacent periosteal bone reaction of the tibia or fibula. Two of us evaluated the location and appearance of periosteal reaction, and one of us evaluated the patients' medical records for evidence of peripheral vascular disease, systemic illnesses, and osteomyelitis. RESULTS: Twelve patients had organized periosteal reactions that resulted in the appearance of ulcer osteoma. None of these patients subsequently developed osteomyelitis. Eight patients had interrupted lamellar nodular periosteal reactions; six of the eight patients had superimposed osteomyelitis. CONCLUSION: Our study showed two types of periosteal response to chronic leg ulcers: a solid organized type that over time formed an ulcer osteoma and a lamellar nodular type that was often associated with osteomyelitis. Both types of ulcers were seen in patients with peripheral vascular disease, IV drug abuse, sickle cell disease, and neurologic impairment.

Percutaneous skeletal aspiration and core biopsy: complementary techniques.

OBJECTIVE: Although core biopsy is the standard for percutaneous bone biopsy in most other organs aspiration biopsy is frequently performed. We prospectively evaluated 138 patients with skeletal lesions, performing both core and aspiration biopsies to determine if these techniques have a complementary role. SUBJECTS AND METHODS: Over a 2-year period, 138 consecutive patients underwent skeletal biopsy. In each patient, two or three histologic cores were obtained percutaneously using standard techniques followed by a single aspiration pass with a 22-gauge spinal needle and 20 cc of negative pressure. Histologic and cytologic evaluations of cores and aspirates were interpreted according to usual pathologic and cytologic criteria. Results were classified as matches (positive or negative), mismatches (aspiration or core only positive), mismatches (either aspiration or core more specific), insufficient samples, inaccurate diagnoses, and both false-negative. RESULTS: Twenty-eight patients had specific neoplasms diagnosed on both core and aspiration biopsy, and 40 patients were negative on both. The diagnosis was made only by core in 17 and only by aspiration in 11. Core was more specific in 11, and aspiration was more specific in seven. There were three insufficient cores and 18 insufficient aspiration specimens. One false-negative result was seen by both techniques, and the cytology of two aspiration biopsies was misinterpreted. CONCLUSION: A complementary role exists for aspiration and core skeletal biopsy, and we suggest both should be routinely performed.

Study of osteomyelitis: utility of combined histologic and microbiologic evaluation of percutaneous biopsy samples.

PURPOSE: To determine the utility of combined histologic and microbiologic evaluation of percutaneous biopsy samples in cases of suspected osteomyelitis. MATERIALS AND METHODS: Twenty-five patients with suspected osteomyelitis were prospectively studied over a 1-year period. With usual trephine techniques under radiologic guidance, core and aspiration biopsy samples were obtained in each patient for both histologic and microbiologic analyses. RESULTS: Sixteen biopsy specimens demonstrated histologic evidence of osteomyelitis. Of these, eight were also culture positive. Seven of the eight culture-negative, histologically positive cases were interpreted as chronic osteomyelitis. In no patient were cultures positive and histologic findings negative. Three of 19 patients with proved osteomyelitis had negative histologic and microbiologic findings. The sensitivity of culture in the diagnosis of osteomyelitis in our study was 42%; the sensitivity of both culture and histologic findings was 84%. CONCLUSION: Although the volume of a biopsy specimen is a major determinant of culture yield, a portion of a percutaneous biopsy sample should be histologically evaluated for possible osteomyelitis.

Osteochondroma: an unusual cause of vascular disease in young adults.

Vascular complications such as pseudoaneurysm, arterial thrombosis, luminal stenosis due to extrinsic compression, deep venous thrombosis, and arteriovenous fistula are known complications of osteochondroma. The authors describe three cases of vascular injury caused by osteochondroma: popliteal artery impingement, popliteal artery pseudoaneurysm formation, and superficial femoral artery pseudoaneurysm with peripheral occlusion of the tibial and peroneal arteries due to embolization. Fifty-six cases of vascular complications due to osteochondroma from the English literature are also reviewed. This entity should be considered in young patients with evidence of peripheral vascular insufficiency or in patients with known osteochondroma who develop symptoms of local pain and swelling in the involved extremity.

Does the use of lidocaine affect the culture of percutaneous bone biopsy specimens obtained to diagnose osteomyelitis? An in vitro and in vivo study.

OBJECTIVE: When percutaneous bone biopsy is done by radiologists, local anesthetics such as lidocaine are routinely used. Although percutaneous bone biopsy of neoplasms is well accepted, it has been suggested that this procedure not be used to diagnose osteomyelitis because of a reported bactericidal effect of lidocaine and related drugs on certain organisms. The purposes of this study were to determine if lidocaine is bactericidal in vitro and to determine if it has an effect on the culture of bacteria in specimens obtained by percutaneous bone biopsy in vivo. SUBJECTS AND METHODS: The minimal inhibitory concentration and minimal bactericidal concentration of 1% lidocaine hydrochloride (10 mg/ml preserved with methylparaben) were determined in vitro for seven bacteria known to be frequent causes of osteomyelitis by using conventional clinical microbiologic methods. Percutaneous core bone biopsy for suspected osteomyelitis was done in 28 patients: 21 with and seven without the use of lidocaine. Sites sampled included vertebrae (14); calcanei, pubis, and ischia (two each); and intervertebral disks (eight). Six of the 21 patients who had percutaneous biopsy with lidocaine also had an open surgical biopsy without lidocaine. The results of cultures of the specimens were compared. Histologic evaluation and radiographic follow-up were used to identify false-negative results. RESULTS: The minimal inhibitory and the minimal bactericidal concentrations, respectively, of lidocaine (in milligrams per milliliter) were as follows: Klebsiella pneumoniae, 5.0 and > 5.0; group B streptococci, 2.5 and 5.0; Staphylococcus aureus, > 5.0; and > 5.0; methicillin-resistant S. aureus, > 5.0 and > 5.0; Escherichia coli, 2.5 and > 5.0; Pseudomonas aeruginosa, 5.0 and 5.0; Salmonella species, 5.0 and > 5.0. We found no difference in bacterial growth and the number of false-negative results between patients who had biopsies with and those who had biopsies without lidocaine. Fifty percent of patients who had growth on cultures of specimens from percutaneous biopsies done with lidocaine had no growth on cultures of specimens from surgical biopsies done without lidocaine. This likely occurred because the surgical specimens were not obtained under cross-sectional imaging guidance. CONCLUSION: Up to a 50% mixture of lidocaine has no significant effect in vitro on the bacterial growth of the seven organisms that cause osteomyelitis most frequently, and no inhibitory effect on bacterial growth was seen in biopsies done with lidocaine in vivo. The inhibitory effect of lidocaine therefore occurs at a greater concentration than is used clinically. We conclude that lidocaine used for biopsy does not interfere with the diagnosis of osteomyelitis.

Medial collateral ligament injuries: evaluation of multiple signs, prevalence and location of associated bone bruises, and assessment with MR imaging.

PURPOSE: To investigate the multiple signs of medial collateral ligament (MCL) sprains, including the location and prevalence of associated bone bruises, and evaluate the accuracy of the criteria proposed for magnetic resonance (MR) imaging in grading these sprains. MATERIALS AND METHODS: MR images were evaluated for signs of MCL injury in 76 patients with MCL sprains and 25 asymptomatic volunteers. These signs were then correlated with standards used to determine MCL injury at clinical evaluation. The grade of MCL injury as determined with MR imaging criteria was compared with clinical findings. RESULTS: All signs demonstrated little interobserver variability and were specific. The most sensitive signs were fascial edema and loss of demarcation from adjacent fat. This MR imaging grading system was inaccurate for classification of grade 3 MCL tears and was only questionably accurate for grades 1 and 2. CONCLUSION: Multiple signs of MCL sprains on MR images have varying sensitivities. MR grading systems may not be accurate for classification of MCL injuries.

Tarsal coalition: depiction and characterization with CT and MR imaging.

PURPOSE: To compare computed tomography (CT) and magnetic resonance (MR) imaging in the detection, localization, and characterization of tarsal coalitions. MATERIALS AND METHODS: Preoperative CT and MR images were obtained for 10 feet in nine patients (eight male and one female patients), aged 11-18 years who were unresponsive to conservative therapy. Results from two blinded readers were compared with results from surgery. RESULTS: Five calcaneonavicular and four medial subtalar coalitions were found at surgery. One patient had synovitis. CT depicted six coalitions and four were characterized correctly, but the fibrous coalitions were not characterized correctly. MR depicted all coalitions and seven were characterized correctly, including the fibrous coalitions. At MR imaging, proliferative synovitis was incorrectly characterized as a fibrous coalition. CONCLUSION: These results suggest that MR imaging depicts all coalitions but may not be able to help differentiate synovitis from fibrous coalitions and that CT has limitations in the depiction of fibrous coalitions.

Percutaneous biopsy of osteolytic lesions: use of a biopsy gun.

Percutaneous bone biopsy with use of traditional trephine needles may be unsuccessful in osteolytic lesions. The authors used an 18-gauge biopsy gun in 25 consecutive lytic lesions. This procedure was safe, effective, and not technically difficult. Use of biopsy guns with detachable handles made positioning with computed tomography (CT) guidance less difficult. The only technical difficulty arose in biopsy of small lesions, in which the gun may misfire when contacting solid bone. A biopsy gun is an effective tool in the biopsy of osteolytic lesions.

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.