Bone contusions of the knee: increased lesion detection with fast spin-echo MR imaging with spectroscopic fat saturation

Sports-related groin pain: evaluation with MR imaging

Our purpose was to assess the role of MRI in evaluating the musculoskeletal system in athletes with chronic pain laterally in the groin of unknown etiology. Magnetic resonance imaging (MRI) of the pubic ring was performed in 11 young athletes (soccer players) with long-standing groin pain. MR findings were compared with plain films and isotope examination (bone scan Tc 99M). Abnormal MRI findings included a broadened and irregular symphysis with a characteristic pattern of low signal intensity on T1W and high signal intensity on T2W images localized in the superior pubic ramus at a distance from the symphysis. Positive findings were also observed on plain films and on nuclear medicine studies. However, the imaging findings in the superior public ramus of the symphysis was located considerably more laterally on MRI. MRI is a valuable method for evaluating discrete and ambiguous pelvic pain in athletes, particularly for identifying concomitant changes in the superior ramus, which may give rise to long-standing pain localized laterally in the groin.

Coronal fat suppression fast spin echo images of the knee: evaluation of 202 patients with arthroscopic correlation

We optimized fat-suppressed fast spin echo (FS-FSE) parameters for coronal imaging of the knee and then evaluated the technique in a clinical setting. Five volunteers and 12 patients were used to evaluate various repetition (TR), echo (TE), and echo train lengths (ETL). Then, 202 patients underwent both knee MR imaging using coronal plane FS-FSE and arthroscopy. The coronal FS-FSE images were compared with radial multiplanar gradient-recalled echo (MPGRE), axial T1-weighted SE, and parasagittal double echo SE images. Proton density images (2,000/19) with an ETL of 2 best depicted the menisci, ligaments, and capsules. The conspicuity of osteochondral abnormalities depicted by the coronal FS-FSE imaging was significantly higher than for axial T1-weighted SE (p < .003) and parasagittal echo SE images (p < .003). The accuracy of the coronal FS-FSE imaging for medial and lateral meniscal tears was 91.6% and 87.6%, respectively. Combined imaging interpretation of the coronal FS-FSE, axial T1-weighted SE, and radial MPGRE imaging improved the accuracy for meniscal tears slightly over any sequence used alone, but the difference was not statistically significant. Fourteen capsular injuries were demonstrated by the coronal FS-FSE imaging. FS-FSE imaging in the coronal plane is a useful complementary sequence in MR examinations of the knee for the evaluation of meniscal tears, capsular injuries, and osteochondral abnormalities.

Subfracture insult to the human cadaver patellofemoral joint produces occult injury

The current criterion used by the automotive industry for injury to the lower extremity is based on visible bone fracture. Studies suggest, however, that chronic joint degeneration may occur after subfracture impact loads on the knee. We hypothesized that subfracture loading of the patellofemoral joint could result in previously undocumented microtrauma in areas of high contact pressure. In the current study, seven patellofemoral joints from human cadavers were subjected to impact with successively greater energy until visible fracture was noted. Transverse and comminuted fractures of the patella were noted at 6.7 kN of load. Approximately 45% of the impact energy then was delivered to the contralateral joint. Subfracture loads of 5.2 kN resulted in no gross bone fracture in five of seven specimens. Histological examination of the patellae horizontal split fracture in the subchondral bone, at the tidemark, or at the interface of calcified cartilage and subchondral bone. The trauma appeared predominantly on the lateral facet, adjacent to or directly beneath preexisting fibrillation of the articular surface. Surface fibrillation was noted in histological sections of control patellae (not subjected to impact loading), but occult damages were not observed. Although the mechanism of this occult trauma is unknown, similar damage has been shown to occur from direct shear loading. As these microcracks can potentiate a disease process in the joint, this study may suggest that the current criterion for injury, based on bone fracture alone, is not sufficiently conservative.

Evaluation of meniscal tears: fast spin-echo versus conventional spin-echo magnetic resonance imaging

RATIONALE AND OBJECTIVES

We compared the performance of fast spin-echo (FSE) with conventional spin-echo (CSE) magnetic resonance (MR) imaging sequences in the detection of meniscal tears.

METHODS

Seventy-three patients underwent MR examination of the knee for suspected internal derangement. Each patient was scanned with a CSE sequence and one of two FSE sequences. The primary difference between the two FSE sequences consisted of the echo train length (ETL). Thirty-seven patients (group 1) were scanned with the FSE I sequence (ETL = 8), and 36 patients (group 2) were scanned with the FSE II sequence (ETL = 4). Menisci were graded as torn or not torn on the basis of their MR appearance. The sequences were compared with each other and with the surgical findings in 31 patients who underwent arthroscopy.

RESULTS

In group 1, there was a significant discrepancy between the CSE and FSE I techniques (p = .006). The FSE I sequence detected only 11 of 19 surgically proven torn menisci as opposed to 18 of 19 detected with the CSE sequence. The FSE II sequence performed significantly better in group 2, with an accuracy equal to that of the CSE sequence.

CONCLUSION

FSE sequences are extremely technique dependent with regard to detecting meniscal tears and should not replace CSE sequences in this setting until further studies are performed to optimize the technique.

Bone bruises: their patterns and significance

MR imaging is sensitive in the detection of occult stress and posttraumatic fractures in and around the knee joint. In some patients, the pain from these bony injuries can mimic that of meniscal tears. The abnormality of the bone may explain completely the patient's symptoms and obviate the need for any further work-up. The types of injuries detected by MRI include bone bruises, stress or insufficiency fractures, and osteochondral fractures. Bone bruises or contusions are characterized by a diffuse or localized pattern of low signal intensity on T1-weighted images without a defined fracture. Blood, edema, hyperemia, and perhaps microfracture of the trabeculae may all contribute to the marrow signal alterations. Anterior cruciate ligament injuries often are accompanied by a characteristic bone contusion pattern, such as hemorrhage or edema in the posterior aspect of the lateral tibial plateau, as well as the anterior aspect of the lateral femoral condyle.