Nancy M. Major

Sensitivity of MR Arthrography in the Evaluation of Acetabular Labral Tears

OBJECTIVE MRI has historically provided suboptimal visualization of tears of the acetabular labrum. Degenerative fraying and underlying cartilage abnormalities can often mimic tears of the labrum on conventional MRI. Administration of intraarticular gadolinium enhances the MRI appearance of the labrum to improve detection of labral abnormalities. This study examined the improved diagnostic sensitivity of MR arthrography compared with conventional MRI and the importance of confining the study to a small field of view. MATERIALS AND METHODS Fifty-one hips were imaged in 48 patients. Fourteen hips underwent conventional MRI with a large field of view (30-38 cm). Seven hips underwent conventional MRI with a small field of view (14-20 cm). Thirty hips underwent MR arthrography with a small field of view (14-20 cm). Labral tears were diagnosed when contrast material was identified within the labrum or between the labrum and the acetabulum, when a displaced fragment was noted, or when a paralabral cyst was identified. All study results were compared with findings at the time of hip arthroscopy. RESULTS Conventional MRI with a large field of view was 8% sensitive in detecting labral tears compared with findings at the time of arthroscopy. Diagnostic sensitivity was improved to 25% with a small field of view. MR arthrography with a small field of view was 92% sensitive in detecting labral tears. CONCLUSION A combination of MR arthrography and a small field of view is more sensitive in detecting labral abnormalities than is conventional MRI with either a large or a small field of view.

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.

MRI of Internal Impingement of the Shoulder

OBJECTIVE Internal impingement is a condition that occurs in athletes in which the shoulder is put in extreme abduction and external rotation during overhead movements. During this motion, the posterior fibers of the supraspinatus tendon, anterior fibers of the infraspinatus tendon, or both can get impinged between the humeral head and the posterior glenoid. The purpose of this study was to evaluate the ability of MRI to show the findings of internal impingement of the shoulder. CONCLUSION As opposed to our six patients with clinically and surgically diagnosed internal impingement, the control patients had isolated pathology in the rotator cuff, labrum, or humeral head. We found that the constellation of findings of undersurface tears of the supraspinatus or infraspinatus tendon and cystic changes in the posterior aspect of the humeral head associated with posterosuperior labral pathology is a consistent finding diagnostic of internal impingement.

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.

Coracohumeral Interval Imaging in Subcoracoid Impingement Syndrome on MRI

OBJECTIVE The coracohumeral interval previously has been described as predictive of subcoracoid impingement on dynamic screening. The purpose of this study was to determine whether a coracohumeral interval acquired from routinely performed MRI can reliably diagnose subcoracoid impingement. MATERIALS AND METHODS Preoperative MRI examinations of 19 patients (16 males, three females) with subsequent surgical confirmation of subcoracoid impingement were reviewed retrospectively and compared with MRI studies of 41 control subjects (22 males, 19 females). Axial and oblique sagittal coracohumeral interval measurements were taken. The morphology of the coracoid process and lesser tuberosity was assessed. Postanalysis application of the data to two smaller groups of patients was performed. The first group consisted of nine subjects (three males, six females) for whom subcoracoid impingement was diagnosed prospectively on the basis of abnormalities found by MRI. The second group consisted of seven patients (two males, five females) who were referred for MRI evaluation because of clinically suspected subcoracoid impingement. RESULTS The average coracohumeral interval for females was 3 mm smaller than that for males. Using sex-adjusted data, we found a statistically significant difference between individuals with or without subcoracoid impingement in the axial coracohumeral interval (p = 0.01). This value, however, was poorly predictive (area under the receiver operating characteristic curve, 0.73). An 11.5-mm axial coracohumeral interval had 84% sensitivity but only 44% specificity. A 10.5-mm axial coracohumeral interval had 79% sensitivity and 59% specificity. The shoulder morphologic features assessed and intraarticular contrast use were not statistically significantly related to the coracohumeral interval. In postanalysis application of data, in the group of nine subjects without clinical diagnosis of subcoracoid impingement, all prospective MRI subcoracoid impingement diagnoses were falsely positive. However, if subcoracoid impingement was the referring diagnosis, prospective MRI evaluation more often was correct (n = 7 [three true-negatives, two true-positives, two false-negatives]). CONCLUSION A sex-adjusted coracohumeral interval of 10.5-11.5 mm, although statistically significantly related to subcoracoid impingement, is poorly predictive of this diagnosis when acquired via routinely performed MRI. Subcoracoid impingement is primarily a clinical diagnosis that may be supported, but not established, by this means.

The relationship of age, gender, and degenerative changes observed on radiographs of the shoulder in asymptomatic individuals

Radiographs of the shoulders of 84 asymptomatic individuals aged between 40 and 83 years were evaluated to determine changes in 23 specific areas. Two fellowship-trained orthopaedic radiologists graded each area on a scale of 0 to II (normal 0, mild changes I, advanced changes II). Logistic regression analysis indicated age to be a significant predictor of change (p < 0.05) for sclerosis of the medial acromion and lateral clavicle, the presence of subchondral cysts in the acromion, formation of osteophytes at the inferior acromion and clavicle, and narrowing and degeneration of the acromioclavicular joint. Gender was not a significant predictor (p > 0.05) for radiological changes. Students t-test determined significance (p < 0.05) between age and the presence of medial acromial and lateral clavicular sclerosis, subchondral acromial cysts, inferior acromial and clavicular osteophytes, and degeneration of the acromioclavicular joint. Radiological analysis in conditions such as subacromial impingement, pathology of the rotator cuff, and acromioclavicular degeneration should be interpreted in the context of the symptoms and normal age-related changes.

The Posterolateral Corner of the Knee

OBJECTIVE The purpose of this article is to review the clinical importance and MRI appearances of injuries to the posterolateral corner of the knee. CONCLUSION Injuries to the posterolateral corner structures of the knee can cause significant disability due to instability, cartilage degeneration, and cruciate graft failure. Becoming familiar with the anatomy of this region can improve ones ability to detect subtle abnormalities and can perhaps lead to improvements in diagnosing and understanding injuries to this area.

Choosing a specialty in medicine: Female medical students and radiology

OBJECTIVE The purpose of this study was to determine whether there are identifiable factors that dissuade female medical students from entering the field of radiology. MATERIALS AND METHODS An anonymous survey was completed by medical students at the end of their third- or fourth-year radiology clinical clerkships at five institutions. In addition to demographic data and residency choice, respondents ranked 10 factors in order of importance to their choice of career. For respondents who did not consider radiology a possible career, a second set of eight factors was ranked for importance in dissuading them. RESULTS Two hundred eighty-eight respondents completed the survey, 152 (53%) men and 136 (47%) women. Both men and women reported direct patient contact and intellectual stimulation as the most important factors in deciding on a specialty. For those who chose radiology, intellectual stimulation and use of emerging technology were significantly (p < 0.05) more important than other factors. The factor that most strongly (96%) dissuaded men and women from a career in radiology was lack of direct patient contact. There was no significant difference between men and women in ranking factors that dissuaded them from applying to radiology residencies; however, nearly one third of the female respondents cited competitiveness of the residency process as important. CONCLUSION Patient contact remains an important factor for medical students choosing a career. To attract high-caliber students, medical schools should expose students to areas of radiology involving patient interaction. Academically qualified women should be identified early during their careers and encouraged to apply for radiology residencies.

The MR imaging appearance of longitudinal split tears of the peroneus brevis tendon.

Purpose Longitudinal split tears of the peroneus brevis tendon have been increasingly reported as a source of lateral ankle pain and disability. MR imaging is useful in identifying the appearance of longitudinal split tears of the peroneus brevis tendon to differentiate this entity from other causes of chronic lateral ankle pain. We observed variations in anatomy associated with these tears. MATERIALS AND METHODS Twenty-two patients (eleven males, eleven females) were identified as having longitudinal split tears of the peroneus brevis tendon. These cases were reviewed retrospectively to evaluate for the following: shape of the peroneus brevis tendon, high signal in the peroneus brevis tendon, tendon subluxation, appearance of the superior peroneal retinaculum, presence of osseous changes in the ankle, lateral ankle ligaments, presence of a bony fibular spur, flattening of the peroneal groove of the fibula and presence of a peroneus quartus. A control group consisted of twenty ankles imaged for reasons other than lateral ankle pain. The same structures were assessed in this group. A Fishers exact P-value was used to determine the significance of each finding in the two groups. RESULTS Statistically significant associated findings were chevron shaped tendon (p = .0001), high signal in the peroneus brevis (p = .0017), bony changes (p = .0001), flat peroneal groove (p = .0001), abnormal lateral ligaments (p = .0004), and lateral fibular spur (p = .0006). Conclusions MR imaging is useful in differentiating longitudinal split tears of the peroneus brevis tendon from other lateral ankle disorders. It can show the extent of the abnormality in the tendon and the associated findings of soft tissue and/or bone variations which must be addressed at the time of surgery.

Malignant giant cell tumor of soft parts

Giant cell tumor of soft parts (GCTSP) is an extremely rare lesion with an unpredictable behavior. Some patients are cured with a simple surgical excision whereas others will develop metastatic disease within a relatively short interval. To date, there are no consistently reliable criteria, either clinical or histologic, to separate the benign from more aggressive lesions. We describe the clinical, histologic and radiologic features of a case with malignant behavior. The patient presented with a fungating skin and soft tissue mass and concurrent pulmonary nodules. The lesion recurred rapidly despite wide resection with negative surgical margins. Biopsy of the pulmonary lesions demonstrated metastatic disease.