MR imaging-based diagnosis and classification of meniscal tears.

Magnetic resonance (MR) imaging is currently the modality of choice for detecting meniscal injuries and planning subsequent treatment. A thorough understanding of the imaging protocols, normal meniscal anatomy, surrounding anatomic structures, and anatomic variants and pitfalls is critical to ensure diagnostic accuracy and prevent unnecessary surgery. High-spatial-resolution imaging of the meniscus can be performed using fast spin-echo and three-dimensional MR imaging sequences. Normal anatomic structures that can mimic a tear include the meniscal ligament, meniscofemoral ligaments, popliteomeniscal fascicles, and meniscomeniscal ligament. Anatomic variants and pitfalls that can mimic a tear include discoid meniscus, meniscal flounce, a meniscal ossicle, and chondrocalcinosis. When a meniscal tear is identified, accurate description and classification of the tear pattern can guide the referring clinician in patient education and surgical planning. For example, longitudinal tears are often amenable to repair, whereas horizontal and radial tears may require partial meniscectomy. Tear patterns include horizontal, longitudinal, radial, root, complex, displaced, and bucket-handle tears. Occasionally, meniscal tears can be difficult to detect at imaging; however, secondary indirect signs, such as a parameniscal cyst, meniscal extrusion, or linear subchondral bone marrow edema, should increase the radiologist's suspicion for an underlying tear. Awareness of common diagnostic errors can ensure accurate diagnosis of meniscal tears. Online supplemental material is available for this article.

High resolution ultrasound features of prostatic rib metastasis: a prospective feasibility study with implication in the high-risk prostate cancer patient.

OBJECTIVE: In a prior study, high resolution ultrasound (US) was shown to be accurate for evaluating rib metastasis detected on bone scan. However, that study did not address the specific US appearance typical of osteoblastic rib metastasis. Our objective was to determine the specific US imaging appearance of osteoblastic prostate carcinoma rib metastasis using osteolytic renal cell carcinoma rib metastasis as a comparison group. MATERIALS AND METHODS: The Institutional Review Board approval and informed consent were obtained for this prospective feasibility study. We performed high resolution US of 16 rib metastases in 4 patients with prostate carcinoma metastases and compared them to 8 rib metastases in 3 male patients with renal cell carcinoma. All patients had rib metastases proven by radiographs and computed tomography (CT). High resolution US scanning was performed by a musculoskeletal radiologist using a 12-5 MHz linear-array transducer. Transverse and longitudinal scans were obtained of each rib metastasis. RESULTS: All 16 prostate carcinoma metastases demonstrated mild cortical irregularity of the superficial surface of the rib without associated soft tissue mass, cortical disruption, or bone destruction. 7 of 8 (88%) renal cell carcinoma rib metastases demonstrated cortical disruption or extensive bone destruction without soft tissue mass. One of 8 (12%) renal cell carcinoma rib metastases demonstrated only minimal superficial cortical irregularity at the site of a healed metastasis. CONCLUSION: Osteoblastic prostate carcinoma rib metastases have a distinctive appearance on US. Our success in visualizing these lesions suggests that US may be a useful tool to characterize isolated rib abnormalities seen on a bone scan in high-risk prostate cancer patients who are being evaluated for curative surgery or radiation treatment.

MR Appearance and Clinical Significance of Changes in the Hip Muscles and Iliopsoas Tendon After Arthroscopic Iliopsoas Tenotomy in Symptomatic Patients.

BACKGROUND: Iliopsoas tenotomy is a treatment for snapping hip. Does this surgical procedure change the surrounding muscle and tendon anatomy? QUESTIONS/PURPOSES: This study seeks to evaluate the changes in the MR appearance of the hip muscles and iliopsoas tendon in patients following arthroscopic iliopsoas tenotomy. METHODS: One hundred sixty-nine consecutive adults were evaluated after iliopsoas tenotomy at the lesser trochanter. Each MR exam was evaluated independently by three radiologists for muscle edema, atrophy (grade 0-4), compensatory hypertrophy, signal within the iliopsoas tendon (increased on T1 or T2 sequences), and iliopsoas tendon morphology (distorted or disrupted) above, at, and below the iliopectineal eminence. A finding was considered positive if reported by two or three of the radiologists. RESULTS: Twenty subjects met the inclusion criteria. Muscle edema was present in 15% (3/20) of subjects within the iliacus, psoas, and quadratus femoris. Atrophy was observed in the following muscles: iliacus 85% (17/20), psoas 75% (15/20), quadratus femoris 10% (2/20), rectus femoris 5% (1/20), vastus lateralis 5% (1/20), and gluteus maximus 25% (5/20). There was no compensatory hypertrophy. Ninety percent (18/20) had increased T1 and 10% (2/20) had increased T2 signal within the iliopsoas tendon. Thirty-five percent (7/20) of the iliopsoas tendons was disrupted and 85% (17/20) was distorted, most commonly below the iliopectineal eminence. CONCLUSION: The majority of postoperative symptomatic patients has atrophy of the iliacus and psoas muscles and distortion and disruption of the iliopsoas tendon and should be recognized as a normal imaging appearance following iliopsoas tendon release.

Imaging appearance of the normal and partially torn ligamentum teres on hip MR arthrography.

OBJECTIVE: The purpose of this study was to evaluate the MR arthrographic appearance of the normal and partially torn ligament teres and to determine if there are imaging criteria for diagnosing partial tears of the ligamentum teres. MATERIALS AND METHODS: One hundred sixteen patients underwent preoperative MR arthrography and hip arthroscopy. Each MR examination was evaluated independently by two musculoskeletal radiologists for the following: size and width of the ligamentum teres in the proximal, mid, and distal thirds of the ligamentum teres; overall length of the ligamentum; number of bundles (1-3); signal intensity (SI) within the ligamentum teres (low, intermediate, high); ligamentum teres fibers (normal, attenuated, thickened, wavy); ligamentum teres integrity (not torn, degenerated, frayed, partial tear); and femoral head edema at the ligamentum teres origin. Statistical analysis was performed using the Kruskal-Wallis rank sum test and Fisher exact test. RESULTS: Twelve of 116 (10%) subjects had partial ligamentum teres tears. One hundred four subjects had an intact ligamentum teres. The average size and width of the intact ligamentum teres was 12.6 × 4.38, 14.9 × 3.5, and 14.3 × 2.7 mm for proximal, mid, and distal, respectively, with an overall length 27.7 mm. It was most common to visualize two bundles in the proximal portion of the normal ligamentum teres (61 and 64/116). Low, intermediate, and high SI was common on all pulse sequences in normal and partially torn ligamentum teres for both readers (p = 0.33-0.84). For reader 1, there was no statistical difference between ligamentum teres fiber appearance in partial tears (p = 0.20). In contrast, reader 2 found partial tears associated with attenuated and wavy appearance (p = 0.003). Reader 1 diagnosed five of 12 (42%), and reader 2 diagnosed eight of 12 (67%) of the partial ligamentum teres tears (p = 0.47 and p = 0.0004). Edema of the femoral ligamentum teres origin was not associated with partial tears (p = 0.33-0.86). Retrospective review revealed that six partial tears had intra substance linear high SI on T2 images and peripheral irregularity, whereas four other tears had high SI within the ligamentum teres fibers without peripheral irregularity. CONCLUSION: The intact and partially torn ligamentum teres can have similar imaging findings on MR arthrography, making the diagnosis of partial ligamentum teres tears difficult. High SI within the substance of the fibers and irregularity suggest partial tearing; however, further research is warranted.

Is there an association between superolateral Hoffa fat pad edema on MRI and clinical evidence of fat pad impingement?

OBJECTIVE: Patients with symptomatic Hoffa fat pad impingement often exhibit fat pad edema on MRI. We studied two patient groups to determine the association between MRI fat pad edema and clinical symptoms of Hoffa fat pad impingement. MATERIALS AND METHODS: We studied 34 consecutive patients with an MRI diagnosis of fat pad edema and no injury in the prior year (group 1) and 47 consecutive patients with a knee MRI examination and no injury in the prior year (group 2). Two sports medicine physicians reviewed the clinical records to confirm or exclude symptomatic fat pad impingement. Two musculoskeletal radiologists independently scored 12 Hoffa fat pad locations for the presence of edema, noting the epicenter. RESULTS: Seventeen of the 34 patients in group 1 had clinical symptoms of fat pad impingement, with all 34 having fat pad edema. There was no association between clinical fat pad impingement and fat pad edema in any specific location (p > 0.183), but patients with fat pad impingement had a greater number of regions of edema (p = 0.005, 0.026 for two observers). In group 2, all four patients with clinical fat pad impingement had MRI fat pad edema, but 38 of the 43 patients without clinical impingement had MRI fat edema; 11 of the 38 had edema centered in the superolateral fat pad. CONCLUSION: Edema is present on MRI in the superolateral region of Hoffa fat pad in patients with clinical fat pad impingement. However, such edema can also be present in patients without symptoms of fat pad impingement.

How I diagnose meniscal tears on knee MRI.

OBJECTIVE: The goal of this article is to summarize the literature about the diagnosis of meniscal tears on MRI including the normal appearance of the meniscus and the appearance of the various types of meniscal tears. In addition, I discuss my experience with the causes of errors in the MR diagnosis of meniscal abnormalities and the nuances of meniscal abnormalities that can mimic a meniscal tear. CONCLUSION: MRI is a highly accurate imaging method for diagnosing meniscal tears. To avoid errors in diagnosing meniscal tears, those interpreting MR examinations of the knee need to be aware of the attachments of the menisci and the normal variations in meniscal anatomy that may resemble a meniscal tear. In addition, by being aware of the patterns of meniscal tears, it is easier to diagnose the less common tears.

Short-term clinical importance of osseous injuries diagnosed at MR imaging in patients with anterior cruciate ligament tear.

PURPOSE: To determine the association between osseous injuries and short-term clinical outcome in patients with anterior cruciate ligament (ACL) tear. MATERIALS AND METHODS: The retrospective study was performed with institutional review board approval, and the requirement to obtain informed consent was waived. The study group consisted of 114 patients (57 male and 57 female patients with a mean age of 26.1 and 25.1 years, respectively) with ACL tear who underwent magnetic resonance (MR) imaging and ACL reconstruction surgery and who filled out International Knee Documentation Committee (IKDC) knee evaluation questionnaires before and 1 year after surgery. All MR images were independently reviewed by two radiologists to determine the presence of a cortical depression fracture on each surface of the knee joint. Bone marrow edema volume was quantified by using segmentation software. Correlation coefficients were used to determine the association between bone marrow edema volume and IKDC score. A multivariate analysis model was used to compare IKDC scores in patients without fracture, patients with a single fracture, and patients with multiple fractures. RESULTS: There was no significant association between total bone marrow edema volume and preoperative or postoperative IKDC score (P = .32 and P = .91, respectively). The mean preoperative and postoperative IKDC scores were 53.4 ± 18.6 and 93.0 ± 5.0, respectively, for patients without fracture, 54.8 ± 13.6 and 87.3 ± 10.8 for patients with a single fracture, and 53.1 ± 17.2 and 83.4 ± 12.7 for patients with multiple fractures. Patients with single and multiple fractures had similar (P = .91) preoperative IKDC scores but significantly lower (P < .001) postoperative IKDC scores compared to patients without fracture. CONCLUSION: Cortical depression fractures in patients with ACL tear are associated with decreased clinical outcome scores 1 year after ACL reconstruction surgery.

MRI appearance of the proximal hamstring tendons in patients with and without symptomatic proximal hamstring tendinopathy.

OBJECTIVE: The purpose of our study was to determine if six MRI findings of the proximal hamstrings differ in frequency in hamstrings with and without symptoms of tendinopathy. MATERIALS AND METHODS: We reviewed the MRI examinations of 118 consecutive patients who had undergone pelvis MRI and evaluation by a musculoskeletal clinical specialist. The proximal hamstrings were evaluated at four consecutive axial locations for tendon size, internal T1 and T2 signal, peritendinous T2 signal, and ischial tuberosity edema. Statistical analysis was performed to determine the association of the MRI findings with symptomatic hamstring tendinopathy. RESULTS: Twenty-one patients had a clinical diagnosis of unilateral proximal hamstring tendinopathy. The mean width or anteroposterior size was significantly larger in symptomatic hamstrings at all three proximal levels (p = 0.002-0.040). More than 90% of hamstring tendons had increased internal T1 or T2 signal that was not associated with hamstring symptoms. Both hamstrings with and without symptoms of tendinopathy had peritendinous T2 signal, but this was significantly more common in hamstrings with tendinopathy symptoms at the three most distal levels (p = 0.001-0.041). Ischial tuberosity edema and a feathery appearance of the peritendinous T2 signal distally were significantly more common in symptomatic hamstrings (p = 0.004 and 0.001, respectively). CONCLUSION: Increased T1 and T2 signal is commonly seen within the proximal hamstrings but is not associated with symptoms of hamstring tendinopathy. Increased tendon size, peritendinous T2 signal with a distal feathery appearance, and ischial tuberosity edema are significantly associated with symptomatic hamstring tendinopathy but can be seen in asymptomatic individuals.

Evaluation of the menisci of the knee joint using three-dimensional isotropic resolution fast spin-echo imaging: diagnostic performance in 250 patients with surgical correlation.

OBJECTIVE: To compare the diagnostic performance of FSE-Cube, a three-dimensional isotropic resolution intermediate-weighted fast spin-echo sequence, with a routine magnetic resonance (MR) protocol at 3.0 T for detecting surgically confirmed meniscal tears of the knee joint in a large patient population. METHODS: FSE-Cube was added to a routine MR protocol performed at 3.0 T on 250 patients who underwent subsequent knee arthroscopy. Three radiologists independently used FSE-Cube during one review and the routine MR protocol during a second review to detect medial and lateral meniscal tears. Using arthroscopy as the reference standard, the sensitivity and specificity of FSE-Cube and the routine MR protocol for detecting meniscal tears were determined for all readers combined. McNemar's tests were used to compare diagnostic performance between FSE-Cube and the routine MR protocol. RESULTS: FSE-Cube and the routine MR protocol had similar sensitivity (95.5%/95.3% respectively, P = 0.94) and similar specificity (69.8%/74.0% respectively, P = 0.10) for detecting 156 medial meniscal tears. FSE-Cube had significantly lower sensitivity than the routine MR protocol (79.4%/85.0% respectively, P < 0.05) but similar specificity (83.9%/82.2% respectively, P = 0.37) for detecting 89 lateral mensical tears. For lateral meniscal tears, FSE-Cube had significantly lower sensitivity (P < 0.05) than the routine MR protocol for detecting 19 root tears but similar sensitivity (P = 0.17-1.00) for detecting all other tear locations and types. CONCLUSION: FSE-Cube had diagnostic performance similar to a routine MR protocol for detecting meniscal tears except for a significantly lower sensitivity for detecting lateral meniscal tears, which was mainly attributed to decreased ability to identify lateral meniscus root tears.

MR arthrographic appearance of the postoperative acetabular labrum in patients with suspected recurrent labral tears.

OBJECTIVE: The objective of our study was to evaluate the MR arthrographic appearance of the acetabular labrum in patients with a suspected recurrent acetabular labral tear after previous arthroscopic resection of a labral tear. CONCLUSION: The labrum after excision will appear shortened on MR arthrography. A recurrent labral tear can be diagnosed by the identification on MR arthrography of a new line to the labral surface, an enlarged and distorted labrum, or a new paralabral cyst.

MR arthrography of the hip: comparison of IDEAL-SPGR volume sequence to standard MR sequences in the detection and grading of cartilage lesions.

PURPOSE: To compare the diagnostic performance of iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL)-spoiled gradient-recalled echo (SPGR) with that of standard magnetic resonance (MR) arthrography sequences for detecting and grading cartilage lesions within the hip joint during MR arthrography. MATERIALS AND METHODS: Following institutional review board approval, 67 consecutive hip MR arthrograms were retrospectively reviewed independently by three musculoskeletal radiologists and one musculoskeletal fellow. IDEAL-SPGR images and the two-dimensional images, the latter from the routine MR arthrography protocol, were evaluated at separate sittings to grade each articular surface of the hip joint. By using arthroscopy as the reference standard, the sensitivity and specificity of the two techniques for detecting and grading cartilage lesions were determined. The McNemar test was used to compare diagnostic performance. Interreader agreement was calculated using Fleiss κ values. RESULTS: For all readers and surfaces combined, the sensitivity and specificity for detecting cartilage lesions was 74% and 77%, respectively, for IDEAL-SPGR and 70% and 84%, respectively, for the routine MR arthrography protocol. IDEAL-SPGR had similar sensitivity (P = .12) to and significantly lower specificity (P < .001) than the routine MR arthrography protocol for depicting cartilage lesions. When analyzing the differences in sensitivity and specificity by reader, the two readers who had experience with IDEAL-SPGR had no significant difference in sensitivity and specificity for detecting cartilage lesions between the two sequences. For all readers and surfaces combined, IDEAL-SPGR had a higher accuracy in correctly grading cartilage lesion (P = .012-.013). Interobserver agreement for detecting cartilage lesions did not differ between the two techniques. CONCLUSION: IDEAL-SPGR had similar sensitivity and significantly lower specificity for detecting cartilage lesions and higher accuracy for grading cartilage lesions than did a routine MR arthrography protocol; the lower specificity of IDEAL-SPGR for detecting cartilage lesions was not seen in experienced readers.

Magnetic resonance imaging in traumatic hip subluxation.

Athletic traumatic hip subluxations are rare. Classic radiographic features have been well described. This case highlights the potential pitfalls of immediate magnetic resonance imaging. Femoral head contusions and acetabular rim fractures are common associated findings usually apparent with magnetic resonance imaging (MRI). However, in this case an MRI done 3 hours post injury failed to show any edema in either location, making the appearance of these findings on subsequent MRIs difficult to interpret. An acute MRI more than 48 hours post injury may have been more helpful.

Arthroscopic partial meniscectomy: MR imaging for prediction of outcome in middle-aged and elderly patients.

PURPOSE: To determine whether preoperative magnetic resonance (MR) imaging could help identify factors associated with poor clinical outcome after arthroscopic partial meniscectomy (APM) in middle-aged and elderly patients with meniscal tears. MATERIALS AND METHODS: The prospective, institutional review board-approved, HIPAA-compliant study was performed with informed consent in 53 men and 47 women (average ages, 54.5 and 56.6 years, respectively). Patients underwent knee MR imaging before APM; clinical symptoms were evaluated preoperatively and 1 year postoperatively with International Knee Documentation Committee (IKDC) questionnaire. Overall severity of knee joint degeneration and severity of each feature of joint degeneration were assessed with Boston Leads Osteoarthritis Knee (BLOK) scoring system. Tear length was measured, and type of meniscal tear was classified. Spearman correlation coefficients and relative risks showed the relationship between clinical outcome after APM (difference between preoperative and postoperative IKDC scores) and severity of joint degeneration. RESULTS: Seventy-four patients with isolated medial APM had a significant (P < .05) inverse correlation between clinical outcome and severity of cartilage loss and bone marrow edema in the medial femoral condyle and medial tibial plateau. Fifteen patients with isolated lateral APM had a significant (P < .05) inverse correlation between clinical outcome and severity of cartilage loss in the lateral femoral condyle and lateral tibial plateau and bone marrow edema in the lateral femoral condyle. One hundred patients with APM had a significant (P < .05) inverse correlation between clinical outcome and severity of meniscal extrusion, total BLOK score, and meniscal tear length. A significantly (P < .05) increased relative risk that a patient would not definitely improve after APM was observed if a meniscal root tear was present. CONCLUSION: Poorer clinical outcome after APM was associated with greater severity of cartilage loss and bone marrow edema in the same compartment as the meniscal tear, greater severity of meniscal extrusion, greater overall severity of joint degeneration, a meniscal root tear, and a longer meniscal tear at preoperative MR imaging.

Association of parameniscal cysts with underlying meniscal tears as identified on MRI and arthroscopy.

OBJECTIVE: Although patients with parameniscal cysts usually have underlying meniscal tears, we noted that this association was less common with anterior lateral cysts. We wished to determine whether the frequency of a meniscal tear underlying a parameniscal cyst varied with cyst location. MATERIALS AND METHODS: We reviewed a database of 7,771 knee MR examinations and identified 134 patients with an MR diagnosis of 138 parameniscal cysts and correlative arthroscopy in 78 patients. We reviewed their medical records and MR studies to determine the location of the cysts and presence of an underlying meniscal tear as determined by MRI or arthroscopy. RESULTS: There were 50 lateral and 88 medial parameniscal cysts. Medial meniscal tears were found underlying a cyst in 96% of arthroscopy patients and 86% of patients who had only MR examinations without a location difference in tears (p = 0.68). Meniscal tears were found on MRI or arthroscopy in all 28 patients with a lateral cyst overlying the body or posterior horn of the lateral meniscus, whereas a tear was found on MRI or arthroscopy in only 14 (64%) of 22 patients with cysts adjacent to or extending to the lateral meniscus anterior horn (p = 0.006). Anterior lateral cysts extended medially either into the root or into Hoffa fat-pad, but the type of extension did not correlate with the presence of an underlying meniscal tear. CONCLUSION: In contrast to medial parameniscal cysts or cysts at other locations adjacent to the lateral meniscus, anteriorly located lateral parameniscal cysts are less likely to have underlying meniscal tears.

Musculoskeletal mnemonics: differentiating features.

Mnemonics are often used in musculoskeletal radiology to help radiologists remember long differential diagnoses. However, unless the specific appearance of each entity on a differential is also recalled, mnemonics become useless. This article presents 8 mnemonics with their corresponding differential diagnoses and distinguishing features. Bubbly lucent lesions of bone are recalled with the FEGNOMASHIC mnemonic, but when only lucent lesions of the diaphysis are included, a more appropriate mnemonic is FEMALE. The lucent lesions of bone differentials often can be narrowed based on specific characteristics of the lesion but radiographic findings elsewhere and clinical information often help. Osseous metastases may present as lucent or sclerotic lesions; when sclerotic, the differential is best remembered with the mnemonic 5 "BEES" Like Pollen. The mnemonic for Wormian bones is PORKCHOPS. The Wormian bones in most of these entities are indistinguishable, so one must rely on radiographic findings outside the skull for diagnosis. By contrast, differentiating causes of acro-osteolysis is often possible with findings seen only on the hand radiographs; the mnemonic for acro-osteolysis is RADSHIP. In skeletally immature patients with frayed metaphyses, the mnemonic is CHARMS. Although the appearance of the fraying is seldom diagnostic, findings in the adjacent portions of the long bones may be characteristic. FETISH is the mnemonic used to remember the entities for the differential diagnosis of vertebra plana. Age of the patient, clinical history, and findings in the adjacent spine often help to provide the specific diagnosis. Nearly all the entities on the differential diagnosis for distal clavicle erosion (mnemonic: SHIRT Pocket) are included in other differentials in this article.

Clinical usefulness of adding 3D cartilage imaging sequences to a routine knee MR protocol.

OBJECTIVE: The objective of our study was to determine whether 3D sequences can improve the diagnostic performance of a routine MR protocol for detecting cartilage lesions within the knee joint at 3 T. SUBJECTS AND METHODS: An iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) spoiled gradient-recalled echo (SPGR) sequence (n = 75 patients) or an IDEAL gradient-recalled acquisition in a steady state (GRASS) sequence (n = 75 patients) was added to routine 3-T knee MR protocol to examine 150 patients who subsequently underwent arthroscopic knee surgery. Each articular surface of the knee joint was graded at arthroscopy. All MR examinations were independently reviewed twice by two musculoskeletal radiologists. During the first review, the routine MR protocol was used alone to grade each articular surface of the knee joint; during the second review, the routine MR protocol was used with IDEAL-SPGR or IDEAL-GRASS. Using arthroscopy as the reference standard, the sensitivity and specificity for detecting cartilage lesions and the proportion of correctly graded cartilage lesions were determined for the routine MR protocol alone and for the routine MR protocol with IDEAL-SPGR or IDEAL-GRASS. The McNemar test was used to compare sensitivity, specificity, and accuracy values and proportions of correctly graded cartilage lesions. RESULTS: There was a statistically significant improvement in the specificity (p < 0.05) but not the sensitivity (p = 0.08-0.32) for detecting cartilage lesions when using the routine MR protocol with IDEAL-SPGR or IDEAL-GRASS. There was also a statistically significant (p < 0.05) improvement in the proportion of correctly graded cartilage lesions when using the routine MR protocol with IDEAL-SPGR or with IDEAL-GRASS. CONCLUSION: Adding 3D sequences to a routine MR protocol improves the diagnostic performance for detecting cartilage lesions within the knee joint at 3 T.

Hip injuries in athletes.

Hip injuries are common in athletes, and there is an extensive differential diagnosis of potential causes. This article reviews the anatomy of the hip, and discusses the imaging findings of hip pathology in athletes including skeletal, intraarticular, and extra-articular abnormalities. The role of radiography, computed tomography (CT), magnetic resonance (MR) imaging, MR arthrography, CT arthrography, and sonography in evaluating each condition is discussed.

3.0-T evaluation of knee cartilage by using three-dimensional IDEAL GRASS imaging: comparison with fast spin-echo imaging.

PURPOSE: To compare the diagnostic performance of iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) gradient-recalled acquisition in steady-state (GRASS) imaging with a routine magnetic resonance (MR) imaging protocol for evaluating knee cartilage at 3.0 T in patients by using arthroscopy as the reference standard. MATERIALS AND METHODS: This prospective Health Insurance Portability and Accountability Act-compliant study was performed with a waiver of informed consent from the institutional review board. IDEAL GRASS was added to routine 3.0-T knee MR protocol performed in 95 symptomatic patients (48 males, mean age, 34.5 years; 47 females, mean age, 35.5 years) who underwent subsequent arthroscopic surgery. Radiologists used the routine MR protocol during the first review and IDEAL GRASS during the second to grade each articular surface and to determine the presence of meniscal tears. By using arthroscopy as the reference standard, the sensitivity, specificity, and accuracy of both imaging methods for detecting cartilage lesions and meniscal tears were determined. RESULTS: By using the z test to compare parameters between methods, the respective sensitivity, specificity, and accuracy for detecting all 192 cartilage lesions were 68.5%, 92.6%, and 84.5% for IDEAL GRASS and 66.1%, 92.9%, and 83.9% for the routine MR protocol. There was no significant difference (P = .34-.83) in parameters between methods for detecting cartilage lesions. The respective parameters for detecting 50 medial meniscal tears were 85.0%, 91.1%, and 87.9% for IDEAL GRASS and 94.0%, 90.0%, and 92.1% for the routine MR protocol. The parameters for detecting 31 lateral meniscal tears were 58.0%, 90.6%, and 80.0% for IDEAL GRASS and 80.1%, 91.4%, and 87.9% for the routine MR protocol. The routine MR protocol had a significantly higher sensitivity for detecting medial meniscal tears (P = .04) and lateral meniscal tears (P = .01) and significantly higher accuracy for detecting lateral meniscal tears (P = .03) than IDEAL GRASS. CONCLUSION: IDEAL GRASS has similar diagnostic performance as routine MR protocol for evaluating the articular cartilage of the knee in clinical patients at 3.0 T but has significantly lower sensitivity and accuracy for detecting meniscal tears.

Ultrasound imaging of normal displacement of the extensor carpi ulnaris tendon within the ulnar groove in 12 forearm-wrist positions.

OBJECTIVE: Instability of the extensor carpi ulnaris (ECU) tendon can be a difficult clinical diagnosis because of normal changes in tendon position during wrist motion. Our goal was to determine the normal variation of ECU tendon displacement in 12 forearm-wrist positions. SUBJECTS AND METHODS: Ultrasound imaging of the ECU tendons of 40 symptom-free wrists of healthy volunteers (13 women, seven men; mean age, 22.3 years; range, 20-25 years) was performed. Each ECU tendon was examined in 12 positions: four wrist positions (ulnar deviation, radial deviation, flexion, and extension) in each of three forearm positions (pronation, supination, and neutral). RESULTS: ECU tendon displacement in the right hand was not significantly different from that in the left, and displacement in men did not differ significantly from that in women. There was a small but significant difference between displacement in the dominant and that in the nondominant hand (p < 0.02). Mean ECU tendon displacement was greatest in the supinated forearm position (p < 0.001) followed by the neutral position (p < 0.001) and was least in the pronated position (p < 0.001). Both ulnar deviation (p < 0.001) and flexion (p < 0.002) were associated with greater ECU tendon displacement than were radial deviation (p < 0.001) and extension (p < 0.002). Maximum percentage displacement volar to the ulnar border of the groove was 50% in flexed supination and ulnar deviation. The maximum displaced distance volar to the ulnar border of the groove was 5 mm. CONCLUSION: Sonographic evaluation of the ECU tendon is simple and practical. Knowledge of normal ECU displacement relative to the ulnar groove may help in evaluation of ulnar-sided wrist pain.

Knee joint: comprehensive assessment with 3D isotropic resolution fast spin-echo MR imaging--diagnostic performance compared with that of conventional MR imaging at 3.0 T.

PURPOSE: To determine whether a three-dimensional isotropic resolution fast spin-echo sequence (FSE-Cube) has similar diagnostic performance as a routine magnetic resonance (MR) imaging protocol for evaluating the cartilage, ligaments, menisci, and osseous structures of the knee joint in symptomatic patients at 3.0 T. MATERIALS AND METHODS: This prospective, HIPAA-compliant, institutional review board-approved study was performed with a waiver of informed consent. FSE-Cube was added to the routine 3.0-T MR imaging protocol performed in 100 symptomatic patients (54 male patients with a median age of 32 years and 46 female patients with a median age of 33 years) who subsequently underwent arthroscopic knee surgery. All MR imaging studies were independently reviewed twice by two musculoskeletal radiologists. During the first review, the routine MR imaging protocol was used to detect cartilage lesions, ligament tears, meniscal tears, and bone marrow edema lesions. During the second review, FSE-Cube with multiplanar reformations was used to detect these joint abnormalities. With arthroscopic results as the reference standard, the sensitivity and specificity of FSE-Cube and the routine MR imaging protocol in the detection of cartilage lesions, anterior cruciate ligament tears, and meniscal tears were calculated. Permutation tests were used to compare sensitivity and specificity values. RESULTS: FSE-Cube had significantly higher sensitivity (P = .039) but significantly lower specificity (P = .003) than the routine MR imaging protocol for detecting cartilage lesions. There were no significant differences (P = .183-.999) in sensitivity and specificity between FSE-Cube and the routine MR imaging protocol in the detection of anterior cruciate ligament tears, medial meniscal tears, or lateral meniscal tears. FSE-Cube depicted 96.2% of medial collateral ligament tears, 100% of lateral collateral ligament tears, and 85.3% of bone marrow edema lesions identified on images obtained with the routine MR imaging protocol. CONCLUSION: FSE-Cube has similar diagnostic performance as a routine MR imaging protocol for detecting cartilage lesions, cruciate ligament tears, collateral ligament tears, meniscal tears, and bone marrow edema lesions within the knee joint at 3.0 T.