Arthur A. De Smet

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.

Reassessment of the MR criteria for stability of osteochondritis dissecans in the knee and ankle

Abstract Objective. T2-weighted MR images has been reported to be an accurate method for assessing osteochondritis dissecans. We reviewed our MR experience to confirm the accuracy of the published criteria of instability. We also assessed the value of each of four MR signs of instability. Design. We reviewed the original MR interpretations, arthroscopic reports, and MR examinations of 40 patients with osteochondritis dissecans of the talar dome or femoral condyles. Arthroscopy was used as the gold standard for stability. The MR examinations were reviewed retrospectively for a high-signal-intensity line or cystic area beneath the lesion, a high-signal-intensity line through the articular cartilage, or a focal articular defect. Patients. All patients who had undergone MR imaging for osteochondritis dissecans from 1990 to 1993 were reviewed. Forty patients were identified who had arthroscopy after the MR examination. There were 30 male and 10 female patients with an average age of 25.7 years. Thirty-one lesions were in a femoral condyle and nine were in the talar dome. Results and conclusions. The original MR interpretations correctly identified 35 of the 36 unstable lesions and all 4 stable lesions, giving a sensitivity of 0.97 and specificity of 1.0. There was a 98% agreement between the original and retrospective diagnoses. A high-signal-intensity line was seen beneath 72% of the 36 unstable lesions. The other three signs were noted in 22–31% of the unstable lesions. Fifty-six percent of the unstable lesions showed only one sign of instability. MR imaging is a highly sensitive method for detection of unstable osteochondritis dissecans. The presence of any one sign indicates instability, the most frequent sign being an underlying high-signal-intensity line. Because we examined only four stable lesions, our 95% confidence interval of 0.40–1.0 for a specificity of 1.0 gives only a limited estimate of the specificity of MR.

Untreated osteochondritis dissecans of the femoral condyles : prediction of patient outcome using radiographic and MR findings

Abstract Objective. We investigated the usefulness of plain film and MR findings in predicting the outcome of conservatively treated patients with femoral osteochondritis dissecans. Design. Without knowledge of the clinical outcome, we retrospectively reviewed the initial plain films and MR examinations. Each MR examination was evaluated for the four MR findings of instability. Patients. Fourteen patients were studied in whom osteochondritis dissecans of a femoral condyle had been treated conservatively for periods ranging from 1.2 to 8.5 years. Results and conclusion. Three of five patients with an open femoral growth plate and one of nine patients with a closed growth plate had a good clinical outcome. Both patients with lesions smaller than 160 mm2 in area had a good outcome and ten of 12 patients with larger lesions had a poor outcome. Both patients with stable lesions by MR imaging had a good outcome while ten of 12 patients with a lesion unstable by MR imaging had poor outcomes. All six patients with a cartilage fracture or articular defect had poor outcomes. The results of this study should be considered preliminary since only 14 patients were followed. However, it appears that a good clinical outcome is likely when the femoral growth plate is open, when the osteochondritis dissecans is small, and when the lesion is stable by MR imaging. When a cartilage fracture or articular defect is found on MR imaging, the patient is likely to have a poor outcome.

Correlation of MRI findings with clinical findings of trochanteric pain syndrome

ObjectiveGreater trochanter pain syndrome due to tendinopathy or bursitis is a common cause of hip pain. The previously reported magnetic resonance (MR) findings of trochanteric tendinopathy and bursitis are peritrochanteric fluid and abductor tendon abnormality. We have often noted peritrochanteric high T2 signal in patients without trochanteric symptoms. The purpose of this study was to determine whether the MR findings of peritrochanteric fluid or hip abductor tendon pathology correlate with trochanteric pain.Materials and methodsWe retrospectively reviewed 131 consecutive MR examinations of the pelvis (256 hips) for T2 peritrochanteric signal and abductor tendon abnormalities without knowledge of the clinical symptoms. Any T2 peritrochanteric abnormality was characterized by size as tiny, small, medium, or large; by morphology as feathery, crescentic, or round; and by location as bursal or intratendinous. The clinical symptoms of hip pain and trochanteric pain were compared to the MR findings on coronal, sagittal, and axial T2 sequences using chi-square or Fisher’s exact test with significance assigned as p < 0.05.ResultsClinical symptoms of trochanteric pain syndrome were present in only 16 of the 256 hips. All 16 hips with trochanteric pain and 212 (88%) of 240 without trochanteric pain had peritrochanteric abnormalities (p = 0.15). Eighty-eight percent of hips with trochanteric symptoms had gluteus tendinopathy while 50% of those without symptoms had such findings (p = 0.004). Other than tendinopathy, there was no statistically significant difference between hips with or without trochanteric symptoms and the presence of peritrochanteric T2 abnormality, its size or shape, and the presence of gluteus medius or minimus partial thickness tears.ConclusionsPatients with trochanteric pain syndrome always have peritrochanteric T2 abnormalities and are significantly more likely to have abductor tendinopathy on magnetic resonance imaging (MRI). However, although the absence of peritrochanteric T2 MR abnormalities makes trochanteric pain syndrome unlikely, detection of these abnormalities on MRI is a poor predictor of trochanteric pain syndrome as these findings are present in a high percentage of patients without trochanteric pain.

Juvenile versus Adult Osteochondritis Dissecans of the Knee: Appropriate MR Imaging Criteria for Instability

PURPOSE To retrospectively compare the sensitivity and specificity of previously described magnetic resonance (MR) imaging criteria for the detection of instability in patients with juvenile or adult osteochondritis dissecans (OCD) of the knee, with arthroscopic findings as the reference standard. MATERIALS AND METHODS Informed consent was waived by the Institutional Review Board for this HIPAA-compliant study. The study group consisted of 32 skeletally immature patients (25 boys, seven girls; mean age, 14.4 years) with 36 juvenile OCD lesions of the knee and 33 skeletally mature patients (25 men, eight women; mean age, 26.2 years) with 34 adult OCD lesions of the knee. All patients had been evaluated with MR imaging and arthroscopy. MR studies were retrospectively reviewed by two radiologists in consensus to determine the presence of previously described MR imaging criteria for OCD instability (ie, high T2 signal intensity rim, surrounding cysts, high T2 signal intensity cartilage fracture line, and fluid-filled osteochondral defect). Sensitivity and specificity of the criteria were calculated separately for juvenile and adult OCD lesions. RESULTS Separately, previously described MR imaging criteria for detection of OCD instability were 0%-88% sensitive and 21%-100% specific for juvenile OCD lesions and 27%-54% sensitive and 100% specific for adult OCD lesions. When used together, the criteria were 100% sensitive and 11% specific for instability in juvenile OCD lesions and 100% sensitive and 100% specific for instability in adult OCD lesions. CONCLUSION Previously described MR imaging criteria for OCD instability have high specificity for adult but not juvenile lesions of the knee.

Arthroscopic Validation of Radiographic Grading Scales of Osteoarthritis of the Tibiofemoral Joint

OBJECTIVE The purpose of this study was to use the Kellgren-Lawrence, Ahlback, and Brandt grading scales to correlate radiographic grade of osteoarthritis with the actual degree of articular cartilage degeneration within the tibiofemoral joint in patients with chronic knee pain. SUBJECTS AND METHODS The study group consisted of 125 patients with symptomatic osteoarthritis of the tibiofemoral joint. For all patients, standing anteroposterior radiographs of the knee were obtained before arthroscopic knee surgery. Each articular surface of the tibiofemoral joint was graded at arthroscopy. Two radiologists retrospectively reviewed the knee radiographs without knowledge of the arthroscopic findings to determine the presence and severity of osteoarthritis of the tibiofemoral joint using the Kellgren-Lawrence, Ahlback, and Brandt grading scales. Correlation coefficients describing the relation between grade of osteoarthritis and severity of articular cartilage degeneration were calculated for each grading scale. RESULTS The correlation coefficients for the Kellgren-Lawrence, Ahlback, and Brandt grading scales were 0.49, 0.41, and 0.56, respectively. The differences between the correlation coefficients for the Kellgren-Lawrence and Ahlback grading scales and the correlation coefficients for the Brandt and Ahlback grading scales were statistically significant (p < 0.05). Many patients with no radiographic findings of osteoarthritis had significant articular cartilage degeneration within the tibiofemoral joint. CONCLUSION The Kellgren-Lawrence and Brandt grading scales were equally effective in defining the presence of and estimating the severity of osteoarthritis of the tibiofemoral joint but had only a moderately strong correlation with the actual degree of articular cartilage degeneration.

Comparison of 1.5- And 3.0-T MR imaging for evaluating the articular cartilage of the knee joint

PURPOSE To retrospectively compare the diagnostic performance of 1.5- and 3.0-T magnetic resonance (MR) imaging protocols for evaluating the articular cartilage of the knee joint in symptomatic patients. MATERIALS AND METHODS This HIPAA-compliant study was performed with a waiver of informed consent from the institutional review board. The study group consisted of 200 symptomatic patients undergoing MR examination of the knee at 1.5 T (61 men, 39 women; mean age, 38.9 years) or 3.0 T (52 men, 48 women; mean age, 39.1 years), who also underwent subsequent arthroscopic knee surgery. All MR examinations consisted of multiplanar fast spin-echo sequences with similar tissue contrast at 1.5 and 3.0 T. All articular surfaces were graded at arthroscopy by using the Noyes classification system. Three musculoskeletal radiologists retrospectively and independently graded all articular surfaces seen at MR imaging by using a similar classification system. The sensitivity, specificity, and accuracy of the 1.5- and 3.0-T MR protocols for detecting cartilage lesions were determined by using arthroscopy as the reference standard. The z test was used to compare sensitivity, specificity, and accuracy values at 1.5 and 3.0 T. RESULTS For all readers combined, the respective sensitivity, specificity, and accuracy of MR imaging for detecting cartilage lesions were 69.3%, 78.0%, and 74.5% at 1.5 T (n = 241) and 70.5%, 85.9%, and 80.1% at 3.0 T (n = 226). The MR imaging protocol had significantly higher specificity and accuracy (P < .05) but not higher sensitivity (P = .73) for detecting cartilage lesions at 3.0 T than at 1.5 T. CONCLUSION A 3.0-T MR protocol has improved diagnostic performance for evaluating the articular cartilage of the knee joint in symptomatic patients when compared with a 1.5-T protocol.

Magnetic resonance imaging of myositis ossificans: analysis of seven cases

Myositis ossificans typically presents as soft tissue swelling with progressive ossification on radiographs. Since magnetic resonance imaging (MRI) is commonly used to evaluate soft tissue masses, we analyzed eight MR examinations in seven patients with myositis ossificans to determine if typical patterns were present. One acute lesion had homogeneous intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Two subacute lesions had low signal intensity margins with slightly increased signal intensity centers on T1-weighted images and very high signal intensity on T2-weighted images. Five chronic lesions had two different patterns. All five were well-defined with low signal intensity borders. Three had signal intensity patterns characteristic of fat on T1-weighted and T2-weighted images. The other two lesions had intermediate signal intensity on T1-weighted images and slightly increased signal intensity on T2-weighted images.We conclude that typical MR appearances of myositis ossificans do exist. A low signal intensity rim is a common finding. However, these patterns are not unique to myositis ossificans and resemble those that have been reported in other lesions. It is important to be aware of the spectrum of MR findings of myositis ossificans when considering the differential diagnosis of a soft tissue mass.

MRI Findings of Osteochondritis Dissecans of the Capitellum with Surgical Correlation

OBJECTIVE Few studies have described the MRI findings of osteochondritis dissecans of the capitellum. Our objective was to describe the MRI findings of 10 patients with osteochondritis dissecans of the capitellum and to correlate the imaging findings with surgical findings of stability and instability. CONCLUSION The MRI findings of unstable and stable osteochondritis dissecans of the capitellum are similar to the findings described for osteochondritis dissecans of the femoral condyles and talar dome. Unstable osteochondritis dissecans lesions are surrounded by a rim of high signal intensity or a fluid-filled cyst on T2-weighted images. Stable osteochondritis dissecans lesions show no surrounding signal abnormality on T2-weighted images.

Vastly Undersampled Isotropic Projection Steady-State Free Precession Imaging of the Knee: Diagnostic Performance Compared with Conventional MR

PURPOSE To compare a vastly undersampled isotropic projection steady-state free precession (VIPR-SSFP) sequence and routine magnetic resonance (MR) imaging for evaluating the cartilage, ligaments, menisci, and osseous structures of the knee in symptomatic patients. MATERIALS AND METHODS All subjects signed written informed consent prior to participation in this prospective, HIPAA-compliant, institutional review board-approved study. VIPR-SSFP was added to the routine 1.5-T MR imaging performed on 95 symptomatic patients (52 men, 43 women; average age, 41.6 years) who subsequently underwent arthroscopic knee surgery. All MR examinations were independently reviewed twice by two musculoskeletal radiologists to detect cartilage lesions, anterior and posterior cruciate ligament tears, meniscal tears, and bone marrow edema lesions, first by using routine MR and second by using VIPR-SSFP. By using arthroscopy as the reference standard, the sensitivity and specificity of both MR protocols were calculated. The z test was used to compare sensitivity and specificity values. RESULTS VIPR-SSFP had significantly higher specificity (P < .01) for helping detect cartilage lesions (92.2% for VIPR-SSFP and 88.4% for routine MR), while routine MR had significantly higher sensitivity (P = .02) and accuracy (P = .05) for helping detect lateral meniscal tears (73.2% sensitivity and 88.4% accuracy for VIPR-SSFP and 87.5% specificity and 93.2% accuracy for routine MR). There was no significant difference (P = .14 to >.99) between VIPR-SSFP and routine MR in the remaining sensitivity and specificity values. VIPR-SSFP helped detect 69.3% of bone marrow edema lesions identified at routine MR. CONCLUSION VIPR-SSFP can provide important clinical information regarding the cartilage, ligaments, menisci, and osseous structures of the knee, but is less sensitive than conventional MR imaging at helping detect lateral meniscal tears and bone marrow edema lesions.