Clyde A. Helms

Magnetic resonance imaging of the body

Part 1 Anatomic atlas. Part 2 Principles of magnetic resonance imaging. Part 3 Clinical applications: neck, chest, cardiovascular system. Part 4 Clinical applications: abdomen and pelvis. Part 5 Clinical applications: musculoskeletal system. Part 6 Magnetic resonance contrast media.

Automated Percutaneous Discectomy: A Prospective Multi-Institutional Study

A prospective multi-institutional study was carried out to evaluate automated percutaneous discectomy in the treatment of lumbar disc herniations. Of the 327 patients who prospectively met the study criteria and were followed for longer than 1 year, 75.2% were successfully treated. When patients (n = 168) who prospectively did not meet the study criteria were treated, the success rate was 49.4%. One case of discitis was reported; otherwise, no other serious complications were noted, and specifically no vascular or nerve damage was encountered. This study indicates that automated percutaneous discectomy can be used successfully to treat lumbar disc herniations with minimal morbidity and emphasizes the need for proper patient selection.

Fibrolipomatous hamartoma : pathognomonic on MR imaging

Abstract Purpose. To assess the MR imaging characteristics, presenting symptoms, age and nerve distribution of fibrolipomatous hamartoma. Design. A computer search was performed of the term fibrolipomatous hamartoma through the musculoskeletal section MR imaging results at our institution from June 7, 1996 to January 21, 1998 followed by a search of the terms lipomatous hamartoma, median nerve, surrounding fat, increased fatty signal, coaxial, and neuroma. MR images and medical files were retrospectively reviewed by two experienced musculoskeletal radiologists for imaging characteristics, nerve and age distribution as well as for history of trauma. In addition three consultation cases from outside institutions were added for determination of image characteristics. Results. Ten fibrolipomatous hamartomas were identified: eight in the median nerve, one in the ulnar nerve and one in the sciatic nerve. Mean age was 32.3 years (range 4–75 years, SD 21 years). Imaging characteristics were serpiginous low-intensity structures representing thickened nerve fascicles, surrounded by evenly distributed fat, high signal intensity on T1-weighted sequences and low signal intensity on T2-weighted sequences. The amount of fat varied; however, distribution in eight cases (80%) was predominantly between nerve fibers rather than surrounding them peripherally. All had a coaxial-cable-like appearance on axial planes and a spaghetti-like appearance on coronal planes that was not seen in any other type of median nerve abnormality imaged during the study period. Conclusion. The MR imaging characteristics of fibrolipomatous hamartoma are pathognomonic, obviating the need for biopsy for diagnosis.

Pelvic stress injuries: the relationship between osteitis pubis (symphysis pubis stress injury) and sacroiliac abnormalities in athletes

Abstract Objective. To demonstrate with radiographic imaging the association between pubic stress injury and sacroiliac abnormalities in athletes. Design and patients. Eleven athletes (9 men and 2 women), comprising seven male long-distance runners, one male soccer player, one male and two female basketball players, were imaged with plain films for complaints of pubic symphysis pain, sciatica, groin pain, or a combination of these complaints. In addition to the plain films, four patients were imaged with CT, two patients had MR imaging, and a bone scan was performed in three patients. Anteroposterior plain films of the pelvis of 20 patients without back pain or pubic pain were evaluated for comparison as a control group (ages 18–72 years, average 49 years; 11 women and 9 men). Results. All athletes showed plain film evidence of either sclerosis, erosions or offset at the pubic symphysis. Four had avulsion of cortical bone at the site of insertion of the gracilis tendon. Four patients demonstrated sacroiliac joint abnormalities on plain films consisting of sclerosis, erosions and osteophytes, and in one of these athletes, bilateral sacroiliac changes are present. Two patients with normal sacroiliac joints on plain films had a bone scan showing increased radionuclide uptake bilaterally at the sacroiliac joints. One patient with both plain film and CT evidence of sacroiliac abnormalities had an MR examination showing abnormal signal at both sacroiliac joints and at the pubic symphysis. A sacral stress fracture was found on CT in one patient with complaints of sciatica. In the control group, six patients, all over the age of 55 years, had mild sclerosis of the symphysis, but no plain film evidence of sacroiliac abnormalities. Conclusion. We have found a group of athletes in whom stress injuries to the pubic symphysis are associated with changes in the sacroiliac joint as demonstrated by degenerative changes or in the sacrum as manifested as a sacral stress fracture. These findings are probably due to abnormal stresses across the pelvic ring structure that lead to a second abnormality in the pelvic ring. The abnormality in the sacrum is not always well seen with conventional imaging. Recognition of the association of stress injury of the symphysis with back pain is important in that it can help avoid inappropriate studies and diagnostic confusion.

Automated Percutaneous Discectomy

Automated percutaneous discectomy is a new, safe procedure for treating herniated lumbar discs still contained by the annulus or posterior longitudinal ligament. In 1985, one of the authors reported a percutaneous nucleus aspiration technique using a 2-mm aspiration probe. This small probe produced minimal tissue damage, allowing the procedure to be done on an outpatient. In this series, 518 patients were treated using this technique for an overall success rate of 85%. Compensation patients, elderly patients, and patients with previous surgery were treated successfully using percutaneous discectomy on an outpatient basis. No intraoperative or postoperative complications occurred.

Discoid lateral meniscus and the frequency of meniscal tears.

Abstract Objective. To use MRI to determine the incidence of discoid lateral menisci in a large study population, and to compare those patients with those without a discoid meniscus in order to assess the impact of a discoid lateral meniscus on the frequency of meniscal tears. Design and patients. Results of 1250 knee MRI studies were retrospectively reviewed. Using the criterion of three or more meniscal body segments on sequential sagittal images, 56 patients were found to have a discoid lateral meniscus. After exclusion of patients with prior knee surgery, 49 patients with a discoid lateral meniscus were compared with 1146 patients without a discoid meniscus. Patients were categorized as having tears of the medial meniscus, lateral meniscus, or both menisci. Results. In our study population, there was a 4.5% incidence of discoid lateral meniscus. Seventy-one percent of patients with a discoid lateral meniscus had one or more meniscal tears, compared with 54% of the comparison group (P=0.01). The frequency of solitary lateral meniscal tears in the discoid group was also higher than in the comparison group: 20%.versus 11% (P=0.03). The frequency of solitary medial meniscal tears and concomitant tears of both menisci were not significantly different between the two groups. Conclusions. The discoid lateral meniscus is an uncommon variant, but not as rare as once believed. Compared with the normal semilunar meniscus, the discoid lateral meniscus has a higher frequency of meniscal tears, and solitary tears of the lateral meniscus are more common in the discoid variant. The frequency of medial meniscal tears is not altered by the presence of a discoid lateral meniscus.

Radial Meniscal Tears: Significance, Incidence, and MR Appearance

OBJECTIVE The purpose of this study was to assess the prevalence of radial meniscal tears at arthroscopy and the ability of MRI to detect radial tears preoperatively. In addition, the ability of four radiologic signs to detect radial tears was assessed. Those signs are the truncated triangle, cleft, marching cleft, and ghost meniscus signs. MATERIALS AND METHODS Arthroscopy of the knee was performed by a single orthopedic surgeon on 196 consecutive patients. The surgeon noted each radial tear he encountered. The MR images that were obtained at our institution were reviewed, whereas those patients who were imaged elsewhere were excluded. The preoperative MRI reports were reviewed to assess the ability to prospectively identify radial meniscal tears. In addition, a retrospective analysis of the MRI studies was performed by two radiologists in which four radiologic signs were applied to detect radial tears. RESULTS Twenty-nine patients (15%) had radial tears at arthroscopy. Eighteen of the 29 patients had their imaging performed at our institution and were selected for review. There were 19 radial tears found at surgery. Seven (37%) of the 19 tears were identified as radial prospectively. Retrospectively, using the four signs for radial tears, reviewers identified 17 (89%) of 19 radial tears. CONCLUSION A more accurate preoperative diagnosis may be rendered using the four described signs to detect radial tears, thus allowing informative preoperative counseling and consideration of new therapies that are available for radial meniscal repair.

Magnetic resonance imaging findings in anterolateral impingement of the ankle

Abstract Objective. To demonstrate the MR imaging findings of anterolateral impingement (ALI) of the ankle. Design and patients. Nine patients with a history of ankle inversion injury and chronic lateral ankle pain were imaged with MR imaging, and the findings correlated with the results of arthroscopy. Three additional patients with clinically suspected ALI of the ankle were also included. Ankle MR imaging studies from 20 control patients in whom ALI was not suspected clinically were examined for similar findings to the patient group. Results. MR imaging findings in the patients with ALI included a soft tissue signal mass in the anterolateral gutter of the ankle in 12 of 12 (100%) cases, corresponding to the synovial hypertrophy and soft tissue mass found at arthroscopy in the nine patients who underwent arthroscopy. Disruption, attenuation, or marked thickening of the anterior talofibular ligament was seen in all cases. Additional findings included signs of synovial hypertrophy elsewhere in the tibiotalar joint in seven of 12 patients (58%) and bony and cartilaginous injuries to the tibiotalar joint in five of 12 (42%). None of the control patients demonstrated MR imaging evidence of a soft tissue mass in the anterolateral gutter. Conclusions. ALI of the ankle is a common cause for chronic lateral ankle pain. It has been well described in the orthopedic literature but its imaging findings have not been clearly elucidated. The MR imaging findings, along with the appropriate clinical history, can be used to direct arthroscopic examination and subsequent debridement.

Epinephrine exacerbates arthritis by an action at presynaptic b2-adrenoceptors

Sympathetic efferents contribute to the severity of joint injury in experimental arthritis in the rat, [Levine J. D. et al. (1986) J. Neurosci. 6, 3423-3429] and beta 2-adrenergic receptor antagonists suppress the disease [Levine J. D. et al. (1988) Proc. natn. Acad. Sci. U.S.A. 85, 4553-4556]. The present study was directed at determining the endogenous ligand for, and target of, the beta 2-receptor contribution to arthritis. We report that adrenal medullectomy significantly reduced joint injury in experimental arthritis, but that severe joint injury was re-established in adrenal medullectomized rats chronically treated with epinephrine or the beta 2-agonist, salbutamol. The ability of these two drugs to enhance joint injury in adrenal medullectomized rats was blocked by sympathectomy. These data suggest that adrenal medulla-derived epinephrine acts at beta 2-adrenoceptors on sympathetic efferent nerve terminals, to contribute to the severity of experimental arthritis.

Observer variability in assessing lumbar spinal stenosis severity on magnetic resonance imaging and its relation to cross-sectional spinal canal area.

Study Design. Magnetic resonance image grading of lumbar spinal stenosis severity was analyzed retrospectively using a common clinical format. Objective. To assess the interobserver and intraobserver reliability of magnetic resonance image used to grade patients with lumbar spinal stenosis, as compared with cross-sectional spinal canal area. Summary of Background Data. Physicians currently classify the degree of lumbar spinal stenosis on magnetic resonance imaging as mild, moderate, or severe. Unfortunately, there is no consensus on criteria for these definitions. Methods. The magnetic resonance image scans of 15 patients with lumbar stenosis were blindly rated by seven observers for the degree of central, lateral recess, and foraminal stenosis between L1–L2 and L5–S1. Weighted kappa statistics were performed to analyze the inter- and intraobserver agreement. Digitized spinal canal area measurements were calculated. Linear regression models were used to assess the reliability of the grading system in predicting the cross-sectional area. Results. The average interobserver kappa score was 0.26. Within different specialties, the interobserver reliability was higher among radiologists (0.40), followed by neurosurgeons (0.21) and orthopedic surgeons (0.15). The average intraobserver kappa score was 0.11, rising to 0.43 after categories were combined (P = 0.001). The classification of central stenosis highly predicted spinal canal area (P < 0.001). Conclusions. The findings indicate only a fair level of agreement among all observers. However, the ability of the various readers to predict the degree of central stenosis was high. Further studies should evaluate a consensus-based, standardized magnetic resonance image classification aimed at improved agreement among observers.