Magnetic resonance evaluation of recurrent disc herniation: is gadolinium necessary?

STUDY DESIGN: Evaluation of magnetic resonance images (MRIs) with surgical reference standard. OBJECTIVES: To determine whether the addition of contrast-enhanced MRI scans increases diagnostic efficacy in the evaluation of recurrent disc herniation. SUMMARY OF BACKGROUND DATA: Many centers now routinely use gadolinium-enhanced examinations in the evaluation of recurrent disc herniation. Others, noting the additional expense of contrast injection, advocate a more limited role for contrast injection and emphasize the importance of T2-weighted axial sequences. METHODS: The study included 165 consecutive patients who were referred to the authors' outpatient imaging center and had a history of previous lumbar discectomy and recurrent back and/or leg pain. The scanning protocol included sagittal and axial T1-weighted spin-echo pre- and postcontrast injection images and sagittal and axial T2-weighted fast spin-echo images. Twenty-eight patients (32 vertebral levels) had subsequent surgical exploration of a disc margin that had previously undergone discectomy. The surgical findings formed the reference standard. Three spine radiologists interpreted the MRI examinations without knowledge of the surgical results. They first interpreted the unenhanced studies, indicated whether they felt contrast injection would be helpful in further evaluation, and then (regardless of this determination) read the postcontrast study. RESULTS: On pre- and post-contrast examinations Reader 1 had a sensitivity of 95% (20/21), a specificity of 100% (10/10), and an accuracy of 97% (30/31). Reader 2 had a sensitivity of 95% (20/21), a specificity of 90% (9/10), and an accuracy of 94% (29/31). Reader 3 had a sensitivity of 90% (19/21), a specificity of 100% (10/10), and an accuracy of 94% on the precontrast examinations. His postcontrast performance demonstrated a sensitivity of 86% (18/21), a specificity of 100% (10/10), and an accuracy of 90% (28/31). In the nine interpretations wherein the readers thought that a contrast-enhanced examination might provide useful additional information, they did not change their interpretations in three cases, improved their interpretations in two, and made their interpretations worse in four on the basis of addition of the enhanced images. CONCLUSIONS: Routine use of contrast-enhanced examinations in patients who have had prior lumbar surgery probably adds little diagnostic value and may be confusing.

Adhesive capsulitis of the wrist.

The authors report the arthrographic features of adhesive capsulitis of the wrist in a patient who had undergone prolonged wrist immobilization. The diagnosis was made on the basis of pain and early filling of the lymphatic vessels during the injection of contrast material, as well as small joint capacity.

Prevalence of previously undetected osteonecrosis of the femoral head in renal transplant recipients.

PURPOSE: To determine the prevalence of osteonecrosis (ON) of the femoral head in renal transplant recipients and determine the natural history of previously undetected lesions. MATERIALS AND METHODS: The hips of 132 renal transplant recipients were examined with magnetic resonance (MR) imaging, with radiographs obtained only in the patients with positive MR images. RESULTS: Ten patients (15 hips) were considered to have ON (prevalence, 7.6%). Eleven of the hips had Ficat stage 0 disease (asymptomatic, preradiographic) and were followed up with serial radiography and MR imaging. Over an average follow-up of 22 months, only one of these lesions showed progression. The other 10 hips did not show progression at MR imaging or radiography. CONCLUSION: Previously undetected ON may have a benign course in many cases. Although a substantial number of patients have previously unsuspected disease, further study is necessary to assess the need for "prophylactic" surgery in such cases.

Interventional musculoskeletal radiology.

Interventional procedures constitute a significant proportion of musculoskeletal radiology. Percutaneous needle biopsy is the ultimate diagnostic technique for the evaluation of musculoskeletal neoplasms and infections. The procedure is accurate, rapid, and safe. It is ideally suited for the diagnosis of metastatic disease and round cell neoplasms. Several needle procedures have been used for the diagnosis and treatment of low back pain. Diskography is primarily a diagnostic test used to determine the symptomatic disk level when multilevel disk disease is present and also to diagnose internal disk disruption. Nerve block with local anesthetic is also used to locate the symptomatic level in patients with multilevel abnormalities. Epidural steroid injection is a therapeutic procedure that commonly is used in patients with low back pain and has been shown to be most effective in patients with disk herniation. Facet joint injection with local anesthetic and steroid is performed to diagnose and treat the facet syndrome. Other needle procedures in the musculoskeletal system include sacroiliac joint aspiration and injection, prosthetic joint aspiration to evaluate potential infection, distention arthrography, and injections of the coccyx for coccydynia.

The prevalence and natural history of early osteonecrosis (ON) of the femoral head.

We performed limited MRI exams of the hips of renal transplant patients to determine the prevalence of osteonecrosis (ON) and the natural history of early lesions. Of 132 subjects, ten patients and 15 hips were considered positive for ON (prevalence = 7.6%, bilaterality = 50%). Eleven of the MRI-positive hips were Ficat Stage 0 (asymptomatic, pre-radiographic) and were followed with serial radiographs and MRI exams. With an average follow-up of 22 months, only one of these early lesions progressed beyond Ficat 0. The other ten hips neither developed progressive MRI changes nor progressed to radiographic stages. Although our follow-up of 22 months is short, the results suggest that early ON may have a benign course in many cases. This supports the recent work of Kopecky et al., who found that many early lesions in renal transplant patients seemingly stabilize or disappear. While the prevalence was lower than in some previous reports, a significant number of patients did demonstrate previously unsuspected disease. Given the recent reports of poor results and high complication rates using "prophylactic" surgery such as core decompression for early ON, we recommend further study into the natural history of these lesions to assess the need for such procedures. In addition, we describe the use of a simple, quick and cost-effective method to screen high risk patients for early ON.

Severity of articular cartilage abnormality in patients with osteoarthritis: evaluation with fast spin-echo MR vs arthroscopy.

OBJECTIVE: The purpose of this study was to assess the accuracy of fast spin-echo MR imaging for depicting the severity of articular cartilage abnormalities in patients with osteoarthritis. SUBJECTS AND METHODS: Twenty-three subjects (10 volunteers less than 35 years old and 13 patients with proved, symptomatic, idiopathic osteoarthritis of the knee of 6 months' to 10 years' clinical duration) underwent fast spin-echo MR imaging of the knee. Two observers graded each articular surface using a five-category scale that took into account abnormalities in the signal intensity of cartilage as well as thickness and contour. The 13 patients also underwent arthroscopic evaluation (as part of a separate protocol) in which cartilage abnormalities were graded by using a similar five-category grading scale, without the graders knowing the results of MR imaging. Articular cartilage was assumed to be normal in the volunteers. RESULTS: One hundred thirty-seven joint surfaces were graded; one surface was obscured by artifact and was excluded. The Spearman rank linear correlation between arthroscopic and MR grading was highly significant (p < .002) for each of the six articular regions evaluated. The MR and arthroscopic grades were the same in 93 (68%) of 137 joint surfaces, they were the same or differed by one grade in 123 surfaces (90%), and they were the same or differed by one or two grades in 129 surfaces (94%). CONCLUSION: Our results suggest that fat-presaturated fast spin-echo MR imaging depicts the severity of articular cartilage abnormalities in osteoarthritis with reasonable accuracy, as compared with arthroscopic evaluation as the standard of reference.

Comparison of oral cholecystography and ultrasonography for evaluating chronic cholecystitis using patient outcome as the reference standard.

RATIONALE AND OBJECTIVES: The authors compared oral cholecystography (OCG) with ultrasound (US) in the detection of chronic gallbladder disease using clinical outcome, rather than pathology results, as the reference standard. METHODS: The authors interviewed 269 patients who underwent either OCG, US, or both, for evaluation of chronic right upper quadrant abdominal pain. The authors considered patients who underwent cholecystectomy with improved symptoms 1 to 4 years after surgery to be reference-standard positive for gallbladder disease, and patients with objective evidence of an alternative diagnosis (eg, peptic ulcer disease), which improved with therapy as reference-standard negative. RESULTS: The sensitivity and specificity of OCG were 83% and 97%, respectively, and for US, 86% and 90%, respectively. CONCLUSIONS: OCG is comparable with US in evaluating of chronic gallbladder disease. In institutions where OCG is used for diagnosing chronic cholecystitis, it may be reasonable to continue using OCG.

Percutaneous needle biopsy of musculoskeletal lesions. 1. Effective accuracy and diagnostic utility.

The utility of a diagnostic test depends not only on its accuracy but also on how its results affect clinical management. We reviewed the results of 102 percutaneous needle biopsies to determine the accuracy, effective accuracy, and diagnostic utility of the procedure. We found percutaneous needle biopsy was similarly accurate in identifying suspected metastatic lesions (82%, n = 44), suspected musculoskeletal infections (90%, n = 29), and suspected primary musculoskeletal tumors (83%, n = 29). Effective accuracy, or accuracy discounted for results with limited clinical utility, was highest in identifying suspected metastatic deposits (77%), slightly lower in suspected infections (72%), and lowest in suspected primary tumors (59%). Diagnostic utility (the probability-weighted sum of the utility values of all possible outcomes of a diagnostic test) for identifying metastatic deposits and infections exceeded that for suspected primary tumors. Percutaneous needle biopsy in patients with suspected primary tumors must be performed with the knowledge that, even though technically accurate, such biopsies may be of limited clinical value. Percutaneous needle biopsy of suspected metastatic lesions and suspected infections, on the other hand, offers high accuracy and high diagnostic utility.

Percutaneous needle biopsy of musculoskeletal lesions. 2. Cost-effectiveness.

We compared the cost-effectiveness of fluoroscopically directed percutaneous needle biopsy (PNB) of musculoskeletal lesions, CT-guided PNB, and open biopsy. We independently assessed the following characteristics: suspected lesion type (metastatic deposit, infection, or primary neoplasm, as determined by clinical findings and radiologic appearance before biopsy); lesion location (axial or appendicular); and appearance on plain films (radiolucent or lytic, sclerotic, vertebral compression fracture, and soft-tissue lesions). In suspected primary tumors, cost-effectiveness of PNB was similar to that of open biopsy: fluoroscopically directed PNB was slightly more cost-effective than open biopsy whereas CT-directed PNB was slightly less cost-effective. Either type of PNB was cost-effective for suspected metastatic deposits and infections, axial and appendicular lesions, radiolucent or lytic lesions, and soft-tissue lesions. We conclude that PNB is cost-effective for most musculoskeletal lesions.

Error in radiology: classification and lessons in 182 cases presented at a problem case conference.

The authors review and classify errors in 182 cases that were presented at problem case conferences between August 1986 and October 1990. Errors were classified by means of a system developed 20 years ago and by means of a system developed within the past several years. The authors found that sources of error have changed very little. Errors usually involved failure to consult old radiologic studies or reports, limitations in imaging technique, acquisition of inaccurate or incomplete clinical history, location of a lesion outside the area of interest on an image, lack of knowledge, failure to continue to search for abnormalities after the first abnormality was found, and failure to recognize a normal biologic variant. Errors included 126 perceptual errors (64 false-negative, 15 false-positive, and 47 misclassification errors) and 56 mishaps, including 38 complications and 18 communication errors. In seven cases nonperception errors occurred because established departmental routines were not followed, and in nine cases a new departmental routine was established after a complication occurred. Departmental policy exerts less effect on perception and interpretation errors.

Hypercard coding system for the ACR Index for Radiological Diagnoses.

We describe a computer version of the Index for Radiological Diagnoses of the American College of Radiology (ACR). This system combines a graphics interface with a search mechanism while preserving the hierarchical structure of the Index. The graphics interface allows easy selection of an anatomic part, while the search mechanism provides the code numbers associated with an entered term. The computer system and the paperback version of the ACR Index were compared by having 52 volunteers (21 radiology faculty members, 21 radiology residents, and 10 medical students) each code 30 cases with the book and a matched set of 30 cases with the computer. The average time to code cases was shorter when the computer was used (52.2 vs 64.5 sec; p less than .0001). Accuracy was higher when the computer was used (96.4% vs 90.4%; p less than .0001). The average confidence in the computer diagnosis was also higher (9.73 vs 9.51, on a scale of 1-10; p = .0016). This system demonstrates the ability of a computer program to outperform an analogous noncomputerized system.

The use of intravenous gadopentetate dimeglumine in magnetic resonance imaging of synovial lesions.

Spin echo T1- and T2-weighted images and intravenously administered gadopentetate dimeglumine-enhanced T1-weighted images were obtained in 4 normal volunteers and 11 patients (11 joints) with painful, intermittent, or persistent joint swelling of unknown etiology. These studies were retrospectively reviewed to assess the benefits of contrast-enhanced magnetic resonance imaging (MRI) in evaluating the synovium. Normal synovium and joint fluid showed no visually apparent enhancement on images obtained immediately after intravenous injection of gadopentetate dimeglumine. Abnormal synovium enhanced significantly, allowing the precise identification of equivocal or unsuspected synovial disease processes. These results suggest that, in selected cases, enhanced MRI can be a useful adjunct in the evaluation of suspected synovial disease processes.

Curriculum for musculoskeletal radiology.

Although general suggestions have been made regarding a radiology residency curriculum, no specific list of entities has been offered. Over the past ten years, we have developed a resident-run morning conference in musculoskeletal radiology that is supervised by faculty and covers a specific curriculum. We offer our curriculum as an example that may assist other departments in developing their own curricula.

Percutaneous procedures for the diagnosis and treatment of lower back pain: diskography, facet-joint injection, and epidural injection.

This review discusses the indications, techniques, complications, and results of three percutaneous procedures used to evaluate and treat lower back pain: diskography, facet-joint injection, and epidural injection. Diskography, performed by injection of contrast medium into the nucleus pulposus, is a technique used to determine the cause of lower back pain in patients in whom findings on other imaging studies are normal or conflicting. Injection of steroids and anesthetic into the facet joints of the lumbar spine is useful to diagnose or treat patients with facet syndrome (back pain caused by abnormalities of the facet joints). Injection of steroids and anesthetic agents into the epidural space provides short-term relief, and can sometimes provide permanent relief, of lower back pain.

Correct placement of epidural steroid injections: fluoroscopic guidance and contrast administration.

We prospectively evaluated 316 caudal-approach epidural steroid injections given by staff radiologists and residents in our department over a 1-year period. Needle placement was checked with fluoroscopy and corrected if necessary. When the needle tip was within the sacral canal, nonionic contrast material was injected. If epidural contrast was not observed, the needle tip was repositioned. Of 111 procedures performed by physicians who had given fewer than 10 epidural steroid injections, 53 (47.7%) resulted in correct nonfluoroscopically directed placement of the needle. For physicians who had performed between 10 and 50 such procedures, 62 (53.4%) of 116 had correct nonfluoroscopically directed placement. For staff physicians, 55 (61.7%) of 89 placements were correct. Even when the sacral hiatus was easily palpated and a staff physician was confident that he or she was within the epidural space, fluoroscopy revealed incorrect placement 14.2% of the time (seven of 49 procedures). In addition, when the needle was positioned within the sacral canal and no blood was evident on Valsalva maneuver or aspiration, the injection was venous in 29 of 316 procedures (9.2%). The presence of blood on the needle stylus was not a reliable indicator of venous placement of the needle. Our findings indicate that fluoroscopy is essential for correct placement of epidural steroid injection. Contrast administration is necessary to avoid venous injection of steroids.

CT-guided percutaneous transpedicular biopsy of the spine.

Occasionally, vertebral body lesions are encountered that are ill suited to the standard posterolateral approach to biopsy. The authors used a transpedicular approach to spine biopsy in six such cases. The authors suggest that this approach be used when the location of the lesion does not allow easy access by means of the posterolateral approach.

Glenoid labrum: evaluation with MR imaging.

Fifteen patients with shoulder instability and nine asymptomatic volunteers were studied with magnetic resonance (MR) imaging. The shoulder joint was visualized by means of arthroscopy or surgery in all patients. Ten patients had abnormalities of the glenoid labrum. Two musculoskeletal radiologists interpreted the MR images of the patients and volunteers without knowledge of the clinical history or surgical results. The surgical and arthroscopic results were used as the standard of reference in symptomatic patients. Observer A achieved a sensitivity of 44.4% and a specificity of 66.7%; observer B had a sensitivity of 77.8% and a specificity of 66.7%. In addition to the poor sensitivities and specificities, there was substantial intra- and interobserver variability. Assuming that the shoulders of the asymptomatic volunteers were normal, the specificities were 100.0% and 88.9% for observers A and B respectively. In this small study, axial MR imaging was relatively insensitive and nonspecific in the evaluation of labral lesions. Further study will be necessary to determine the utility and limits of MR imaging in this regard.

Pisiform fractures.

Fractures of the pisiform are often missed due to improper radiographic evaluation and a tendency to focus on other, more obvious injuries. Delayed diagnosis may result in disabling sequelae. A high index of clinical suspicion and appropriate radiographic examination will establish the correct diagnosis. Ten patients with pisiform fracture are presented. The anatomy, mechanism of injury, clinical presentation, radiographic features, and evaluation of this injury are discussed.

Magnetic resonance imaging of myxoid containing tumors.

Myxoid tissue forms part of many benign and malignant soft-tissue tumors. The advent of percutaneous needle biopsy has made it important to be aware of the diagnostic implications of biopsy samples containing myxoid tissue. To determine whether the magnetic resonance imaging (MRI) characteristics could help establish the diagnosis, we compared the MR images of 11 tumors containing myxoid tissue with the resected tumor tissue. In our small series of these rare tumors, the MRI characteristics allowed differentiation of intramuscular myxomas from malignant neoplasms containing myxoid tissue. Intramuscular myxomas meet the following conditions: (a) they are well circumscribed; (b) they arise within muscle; (c) T1-weighted images demonstrate uniform, decreased signal intensity; (d) T2-weighted images demonstrate uniform increased signal intensity; (e) contrast-enhanced images exhibit an inhomogeneous increase in signal intensity. If any of these conditions is not met, then a malignancy containing myxoid tissue should be suspected.