MRI to Arthroscopy Correlations in SLAP Lesions and Long Head Biceps Pathology.

Superior labral anterior and posterior lesions and long head biceps injury are 2 common sources of shoulder pain. The presenting complaints and physical examination findings for these etiologies are often nonspecific, making diagnosis challenging. Further complicating their diagnoses, these 2 pathologies often cooccur together or with other shoulder pathologies such as subacromial bursitis, rotator cuff tear, and shoulder instability. However, with advancement in magnetic resonance imaging and shoulder arthroscopy techniques the ability to diagnose and treat these pathologies has vastly improved over the past 30 years. This review provides a case-based description of the correlation between magnetic resonance imaging and arthroscopic findings in common superior labral anterior and posterior and long head biceps injury, accompanied with current management strategies.

Isolated sciatic nerve entrapment by ectopic bone after femoral head fracture-dislocation.

Although posttraumatic pelvic heterotopic ossification (HO) after hip fracture dislocation is well established, and nerve encasement by HO may occur, the development of neurologic deficit is rare. A thorough history and adequate clinical suspicion are imperative in the workup of affected patients. Computed tomography and magnetic resonance imaging provide good visualization and assist in surgical planning. If symptoms persist and are recalcitrant to conservative management, surgical intervention with HO excision and nerve neurolysis can be performed with success.

Evaluation of the glenoid labrum with 3-T MRI: is intraarticular contrast necessary?

OBJECTIVE: The purpose of this study was to evaluate the diagnostic accuracy of 3-T MRI versus 3-T MR arthrography for assessing labral abnormalities in the shoulder using arthroscopy as the gold standard. SUBJECTS AND METHODS: Forty-two patients (28 men, 14 women; mean age, 33 years) underwent MR arthrography and conventional MRI of the same shoulder. Two patients underwent bilateral shoulder examinations, for a total of 44 shoulder examinations. Twenty-two shoulders underwent arthroscopy. The results of arthroscopy were used as the reference standard. Three musculoskeletal radiologists prospectively and independently interpreted MRI and MR arthrography examinations. Differences in performance of conventional MRI and MR arthrography were analyzed for statistical significance by the two-tailed McNemar test. RESULTS: Of the 22 arthroscopies performed, 26 labral tears were found in 18 shoulders and four shoulders were normal with respect to the labrum. There were 12 superior, nine posterior, and five anterior labral tears identified at arthroscopy. By consensus review, conventional MRI identified nine of 12 superior (sensitivity, 75%; specificity, 100%), seven of nine posterior (sensitivity, 78%; specificity, 92%), and three of five anterior (sensitivity, 60%; specificity, 94%) labral tears. MR arthrography identified nine of 12 superior (sensitivity, 75%; specificity, 100%), eight of nine posterior (sensitivity, 89%; specificity, 100%), and five of five anterior (sensitivity, 100%; specificity, 100%) labral tears. CONCLUSION: Although the power of our preliminary study is small, the results suggest that intraarticular contrast material is helpful in diagnosing labral tears in the shoulder, particularly tears of the anterior labrum. Our preliminary results suggest that MR arthrography adds value for diagnosing labral tears in the shoulder compared with conventional MRI even at 3 T.

Utility of CT-guided biopsy of suspicious skeletal lesions in patients with known primary malignancies.

OBJECTIVE: Patients with a known primary malignancy and one or more suspicious skeletal lesions are often assumed to have skeletal involvement by the known malignancy. We set out to determine how often one would be correct in making this assumption. MATERIALS AND METHODS: All CT-guided bone biopsies performed at our institution between January 2006 and January 2009 in patients with a history of a single biopsy-proven malignancy were retrospectively reviewed. Pathology results were assigned to one of three outcomes: skeletal involvement by known malignancy, newly diagnosed malignancy, or no malignancy identified. Patients categorized as no malignancy identified required repeat biopsy or stability on follow-up imaging for confirmation. RESULTS: Of 104 patients with a known primary malignancy, 11 were excluded. Of the 93 included patients, there was skeletal involvement by the known malignancy in 82 (88%), a newly diagnosed malignancy in seven (8%), and no malignancy identified in four (4%). CONCLUSION: Biopsy of a suspicious skeletal lesion in a patient with a solitary known malignancy reveals a newly diagnosed malignancy or no evidence of malignancy in 12% of patients, emphasizing the importance of biopsy.

Clinical significance of intramuscular cysts in the rotator cuff and their relationship to full- and partial-thickness rotator cuff tears.

OBJECTIVE: Secondary signs have been sought to help in the MR diagnosis of rotator cuff tears, especially partial-thickness tears. We sought to determine whether intramuscular cysts are always present with rotator cuff tears and the types of rotator cuff tears with which they present, and to establish the clinical significance of finding intramuscular cysts. MATERIALS AND METHODS: Retrospective analysis of our institution's database of 5,101 MRI examinations of the shoulder during an 8-year period resulted in 187 examinations in 185 patients who were thought to have intramuscular cysts. Of the 187 examinations, 134 shoulders in 132 patients (62 women, 70 men) met our criteria for an intramuscular cyst. RESULTS: Of the 134 shoulders with intramuscular cysts, 102 (76.1%) showed imaging findings of both intramuscular cysts and rotator cuff tears. Thirty-two of the 134 (23.9%) shoulders were diagnosed with only an intramuscular cyst and were not associated with a rotator cuff tear. Fifty-five of 102 (53.9%) shoulders consisted of an intramuscular cyst associated with a full-thickness rotator cuff tear, and 47 of 102 (46.1%) shoulders presented with a partial-thickness rotator cuff tear. Forty-eight of 102 (47.1%) shoulders with both an intramuscular cyst and a rotator cuff tear also underwent the reference standard arthroscopy examination to confirm the MRI findings. In 46 of 48 (95.8%) shoulders that underwent arthroscopy, the findings confirmed the imaging evidence; the other two cases were shown to have an intact rotator cuff at arthroscopy. CONCLUSION: Our study echoes the findings of previous studies that suggest a relationship between intramuscular cysts and full- and partial-thickness rotator cuff tears but illustrates that the incidence of an isolated intramuscular cyst is higher than previously expected. When intramuscular cysts present with rotator cuff tears, they present with full- and partial-thickness rotator cuff tears in relatively equal proportions. The presence of an intramuscular cyst on MRI, although it may be an isolated finding, should prompt a thorough search of all the rotator cuff tendons for tears so that the patient may receive appropriate follow-up.

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 one's ability to detect subtle abnormalities and can perhaps lead to improvements in diagnosing and understanding injuries to this area.

Musculoskeletal radiology curriculum for radiology residents.

This article outlines a curriculum for resident education in musculoskeletal radiology that addresses the current requirements for assessment of the general competencies as set forth by the Accreditation Council for Graduate Medical Education.

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.

Magnetic resonance imaging findings associated with surgically proven rotator interval lesions.

OBJECTIVE: To identify shoulder magnetic resonance imaging (MRI) findings associated with surgically proven rotator interval abnormalities. MATERIALS AND METHODS: The preoperative MRI examinations of five patients with surgically proven rotator interval (RI) lesions requiring closure were retrospectively evaluated by three musculoskeletal-trained radiologists in consensus. We assessed the structures in the RI, including the coracohumeral ligament, superior glenohumeral ligament, fat tissue, biceps tendon, and capsule for variations in size and signal alteration. In addition, we noted associated findings of rotator cuff and labral pathology. RESULTS: Three of three of the MR arthrogram studies demonstrated extension of gadolinium to the cortex of the undersurface of the coracoid process compared with the control images, seen best on the sagittal oblique images. Four of five of the studies demonstrated subjective thickening of the coracohumeral ligament, and three of five of the studies demonstrated subjective thickening of the superior glenohumeral ligament. Five of five of the studies demonstrated a labral tear. CONCLUSIONS: The MRI arthrogram finding of gadolinium extending to the cortex of the undersurface of the coracoid process was noted on the studies of those patients with rotator interval lesions at surgery in this series. Noting this finding-especially in the presence of a labral tear and/or thickening of the coracohumeral ligament or superior glenohumeral ligament-may be helpful in the preoperative diagnosis of rotator interval lesions.

Upper extremity compartmental anatomy: clinical relevance to radiologists.

Malignant tumors of the upper extremity are uncommon, and their care should be referred to specialized facilities with experience treating these lesions. The Musculoskeletal Tumor Society (MSTS) staging system is used by the surgeon to determine appropriate surgical management, assess prognosis, and communicate with other healthcare providers. Magnetic resonance imaging (MRI) is employed pre-operatively to identify a lesion's compartment of origin, determine extent of spread, and plan biopsy and resection approaches. Involvement of neurovascular structures may result in devastating loss of upper extremity function, requiring amputation. Violation of high-resistance compartmental barriers necessitates more extensive surgical resection. Biopsy may be performed by the radiologist using imaging guidance. Knowledge of compartmental anatomy allows the radiologist or surgeon to use an easily excisable biopsy approach and prevent iatrogenic spread to unaffected compartments. Case examples are presented to illustrate the importance of compartmental anatomy in the management of benign and malignant upper extremity tumors.

Evaluation of the acetabular labrum at 3.0-T MR imaging compared with 1.5-T MR arthrography: preliminary experience.

Institutional review board approval and informed consent were obtained for this HIPAA-compliant study. The purpose of this study was to prospectively compare imaging of the acetabular labrum with 3.0-T magnetic resonance (MR) imaging and 1.5-T MR arthrography. Eight patients (four male, four female; mean age, 38 years) with hip pain suspicious for labral disease were examined at both MR arthrography and MR imaging. Presence of labral lesions, paralabral cysts, articular cartilage lesions, subchondral cysts, osteophytes, and synovial herniation pits was recorded. There was arthroscopic correlation of findings in five patients. MR imaging depicted four surgically confirmed labral tears that were identified at MR arthrography, as well as one that was not visualized at MR arthrography. MR imaging helped identify all other pathologic conditions that were diagnosed at MR arthrography and helped identify one additional surgically confirmed focal articular cartilage lesion. These results provide encouraging support for evaluation with 3.0-T MR imaging over 1.5-T MR arthrography.

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.

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.

Role of MRI in prevention of metatarsal stress fractures in collegiate basketball players.

OBJECTIVE: Metatarsal stress fractures are common and represent debilitating and potentially season-ending injuries for basketball players. Bone marrow edema is readily visualized on MRI and can be a sign of stress changes. Twenty-six asymptomatic male National Collegiate Athletic Association basketball players were imaged before the 2003-2004 season and 14 players were reimaged after the conclusion of the season with a screening study of long- and short-axis fat-suppressed T2-weighted images (TR/effective TE, 3,500/56) to identify bone marrow edema in the metatarsals. CONCLUSION: Six (12%) of 52 feet showed a signal indicating bone marrow edema in the metatarsals. MRI depicts bone marrow edema in the feet before a fracture becomes evident. Identification of this edema may reveal stress changes, allowing early treatment and prevention of debilitating stress fractures.

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.

The drop sign, a radiographic warning sign of elbow instability.

Persistent instability or redislocation is uncommon but of significant concern in treating elbow dislocations. Finding an objective, static radiographic sign that might correlate with the presence of instability was the purpose of this study. Pre- and post-reduction radiographs of 10 consecutive simple and complete adult elbow dislocations were reviewed and compared with radiographs of 20 consecutive adult elbows without any trauma history. A statistically significant measured increase in static ulnohumeral distance was noted on the routine unstressed post-reduction lateral radiographs of patients sustaining dislocation. We have termed this increased distance the drop sign. It differs from the radiographic ulnohumeral separation noted during O'Driscoll's test for posterolateral rotary instability, which is present only with axial compression. The drop sign becomes concerning only if persistent after the first reduction radiograph and may be a warning sign of the presence of instability.

Comparison of fast spin-echo versus conventional spin-echo MRI for evaluating meniscal tears.

OBJECTIVE: We compare sensitivities of conventional spin-echo and fast spin-echo sequences in the evaluation of meniscal tears. Furthermore, we reevaluate the results from prior studies comparing these two sequences to understand why there are differing conclusions regarding the efficacy of fast spin-echo sequences as a commensurate replacement for conventional spin-echo sequences. MATERIALS AND METHODS: We used records from a control group of 64 patients (128 menisci) who had undergone arthroscopy to determine the sensitivity of conventional spin-echo sequences for detecting meniscal tears. Two hundred sixteen consecutive patients (432 menisci) were then imaged using conventional spin-echo and fast spin-echo sequences to evaluate for meniscal tears. Both sequences were proton density-weighted with fat suppression. RESULTS: Of the 432 menisci, 170 tears were detected on conventional spin-echo imaging. Only 128 tears were detected on the fast spin-echo sequence. The sensitivities of conventional spin-echo and fast spin-echo imaging were found to be 93% and 80%, respectively. In addition, findings from conventional spin-echo and fast spin-echo sequences were discordant for 72 menisci (17%, p < 0.01). CONCLUSION: The sensitivities of conventional spin-echo and fast spin-echo imaging for detecting meniscal tears have been shown to be greater than 90% and approximately 80%, respectively. However, some authors advocate substituting conventional spin-echo imaging with fast spin-echo imaging. We urge the abandonment of fast spin-echo imaging for evaluating meniscal tears because a loss of greater than 10% in sensitivity is unacceptable.

Lower extremity compartmental anatomy: clinical relevance to radiologists.

A thorough understanding of compartmental anatomy is necessary for the radiologist participating in the care of a patient with a lower extremity musculoskeletal malignancy. Localization of tumor to compartment of origin and identification of extracompartmental spread preoperatively are needed to correctly stage a tumor and determine the appropriate surgical management. An understanding of the locations of fascial boundaries, extracompartmental tissues, and neurovascular structures of the thigh and lower leg facilitates this diagnostic process. For the radiologist planning to biopsy a suspicious musculoskeletal lesion, consultation with the referring orthopaedic surgeon is recommended in order to jointly select an appropriate percutaneous biopsy approach. Adequate preprocedural planning ensures selection of an approach which prevents iatrogenic tumor spread beyond the compartment of origin, protects neurovascular structures, and allows complete resection of the biopsy tract and scar at the time of surgical resection without jeopardizing a potential limb-sparing procedure. Cross-sectional anatomic review and case examples demonstrate the importance of a detailed understanding of compartmental anatomy when approaching the patient with a lower extremity musculoskeletal tumor.

MR imaging appearance of 180-360 degrees labral tears of the shoulder.

Glenoid labral tears exceeding 180 degrees are an uncommon entity in which characteristic clinical and MR imaging features can lead to a more accurate preoperative diagnosis. We provide a description of glenoid labral tears that exceed 180 degrees, and their characteristic magnetic resonance imaging features. In the young, heavily muscled male athlete, the identification of multiple sites of labral pathology and isolated, extensive posterior labral injuries are features that should raise suspicion for labral tears that exceed 180 degrees.