RESUMEN

The aim of this study was to investigate the presence of fibrocartilage within the distal posterior tibial tendon (PTT) before its division correlating with size and signal variation on MR images through a radio-anatomic and pathologic study. Eight fresh cadaveric feet underwent MR imaging were cut into 4-mm slices in the axial plane. The PTT specimens were harvested at the tendon distal portion before its division and sent to pathology. Thirty-three asymptomatic subjects underwent axial double-echo turbo-spin-echo MR imaging. Proximal and distal PTT signal and diameter were evaluated. In cadavers, every PTT flared distally. Intratendinous fibrocartilage and ossified sesamoid were found in, respectively, 87.5 and 12.5% of the cases. Distal PTT flaring was demonstrated in 100% of the asymptomatic subjects (mean diameter 8 mm). An intratendinous high signal intensity on proton-density-weighted images and sesamoid bone were evidenced in, respectively, 36 and 33% of the cases. Proximally, PTT presented a 4-mm mean diameter and was hypointense in 100% of the cases. Only one accessory navicular bone was detected. Laterally off-centered increased intratendinous signal intensity as well as PTT distal widening with otherwise normal MR imaging features are related to an intratendinous fibrocartilage.

Asunto(s)

RESUMEN

The aims of this study were to (a) provide an accurate description of the anterior talo-fibular ligament (ATFL) multifasciculated feature by means of cadaver study, and (b) to further delineate contour and signal variations on MR images related to this feature in a group of asymptomatic subjects. After MR imaging, three cadaveric feet were frozen and cut in the coronal plane. The ATFL were harvested and sent to pathology. Another cadaveric foot was dissected. The MR imaging was performed in 3 healthy volunteers and 19 patients without pathology of the ATFL. For both cadaveric feet and subjects, MR imaging protocol consisted of axial and coronal proton-density (PD) and T2-weighted turbo-spin-echo (TSE) sequences (TR/TE: 3500 ms/17-119 ms). On MR images, ATFL signal and fascicle numbers were assessed, respectively, in the axial and coronal planes. Gross anatomy and pathology confirmed the ATFL bifasciculated aspect. On cadaveric coronal MR images, 3 of 4 ATFLs were bifasciculated and one of four was striated. On patients' coronal MR images, 2 of 22 of the ATFL were monofasciculated, 12 of 22 bifasciculated, and 8 of 22 striated. On axial MR images, 16 of 22 of the ATFL demonstrated a low signal intensity and 8 of 22 an intraligamentous subtle increased signal intensity. Two of 22 of the ATFL had contour irregularities. Isolated anterior talo-fibular intraligamentous signal abnormalities or contour irregularities on axial PD and T2-weighted MR images with an otherwise normal ATFL aspect on coronal MR images and no other MRI criteria for ankle sprain may reflect normal anatomy.

Asunto(s)

Asunto(s)

RESUMEN

The purpose of this paper is to present the contribution of imaging in the assessment of synovial diseases, especially in the differentiation between infectious synovitis and rheumatoid arthritis, and in the diagnosis of tumoral and pseudotumoral synovial lesions (idiopathic (osteo)chondromatosis, pigmented villonodular synovitis, synovial hemangioma, lipoma arborescens...).

Asunto(s)

RESUMEN

OBJECTIVE: We determined the prevalence of clinically silent Morton's neuroma and searched for distinguishing MR imaging features of Morton's neuroma in patients with clinical complaints related to this entity and in patients with clinically silent lesions. MATERIALS AND METHODS: One radiologist who was unaware of clinical findings retrospectively reviewed 85 consecutive foot MR examinations. MR imaging criteria for Morton's neuroma included a low- to intermediate-signal-intensity soft-tissue mass in the intermetatarsal space. The size, location, and signal intensity of each neuroma and the presence of intermetatarsal bursae were recorded. The patients were subdivided into symptomatic or asymptomatic groups on the basis of the patients' answers on a questionnaire documenting the locations and characteristics of symptoms and discussions with each referring physician about clinical findings. Surgical confirmation was available in eight of 25 symptomatic patients. RESULTS: The prevalence of Morton's neuroma in patients with no clinical evidence of this condition was 33% (19/57). Twenty-five patients had symptomatic Morton's neuroma, 19 had Morton's neuroma based on MR imaging findings with no clinical manifestations, and 41 did not have Morton's neuroma. Slightly larger lesions were observed in the symptomatic group, although significant overlap was noted between the two groups. The mean transverse diameter of symptomatic neuromas was 5.3 mm (standard deviation, 2.14) compared with 4.1 mm (standard deviation, 1.75) for asymptomatic neuromas; this difference was marginally significant (p = 0.05). CONCLUSION: The MR imaging diagnosis of Morton's neuroma does not imply symptomatology. Careful correlation between clinical and MR imaging findings is mandatory before Morton's neuroma is considered clinically relevant.

Asunto(s)

RESUMEN

OBJECTIVE: The purpose of this study was to compare the diagnostic efficacy of low- and high-field-strength MR imagers in the diagnosis of anterior cruciate ligament tears and meniscus tears. SUBJECTS AND METHODS: In 219 patients with suspected internal derangement of the knee, MR imaging at 0.2 and 1.5 T was performed with similar sequences. Only patients with surgically confirmed diagnosis (n = 90) were included in the statistical analysis. Radiologists were unaware of diagnosis and field strength. Sensitivity, specificity, diagnostic accuracy, and inter- and intraobserver variability were determined. RESULTS: There was excellent correlation between the field strengths in accuracy, sensitivity, and specificity for anterior cruciate ligament and meniscus tears. Accuracy for medial meniscus, lateral meniscus, and anterior cruciate ligament tears was 91-93%, 88-90%, and 93-96%, respectively, at 0.2 T and 91-94%, 91-93%, and 97-98%, respectively, at 1.5 T. Inter- and intraobserver variability values showed excellent correlation (kappa > 0.8). CONCLUSION: The level of diagnostic accuracy in anterior cruciate ligament tears and meniscus tears is comparable for low- and high-field-strength MR imagers.

Asunto(s)

RESUMEN

PURPOSE: To determine the magnetic resonance (MR) imaging features that characterize tear of the peroneus longus tendon at the midfoot. MATERIALS AND METHODS: Medical records and MR images in nine patients with a tear of the middle segment of the peroneus longus tendon were retrospectively reviewed. All nine patients had undergone routine ankle MR imaging; three had undergone additional oblique coronal MR imaging. Surgical proof of a tear was available for three patients. RESULTS: Partial tear was present in four patients, and complete tear was present in five. Partial tears were characterized by heterogeneous signal intensity and thickening of the tendon. Complete tears were characterized by discontinuity of the tendon. Additional findings included fluid in the tendon sheath (n = 6), marrow edema of the lateral calcaneal wall (n = 3), enlarged peroneal tubercle (n = 3), and tear of the peroneus brevis tendon (n = 2). The extent of the tear was better assessed with oblique coronal MR images. CONCLUSION: The characteristic MR imaging appearance of complete or partial tear of the middle portion of the peroneus longus tendon includes foci of increased signal intensity in the distal tendon, morphologic alterations, and/or discontinuity of tendon. Bone marrow edema along the lateral calcaneal wall may be suggestive of the diagnosis. Additional oblique coronal midfoot MR images may help in assessment of the extent of the tear.

Asunto(s)

RESUMEN

Cortical septic osteitis is defined as a predominant or exclusive infection of the cortex which may lead to diagnosis pitfalls. With the two cases presented here, principal radiological features allowing a correct diagnosis are recalled.

Asunto(s)

RESUMEN

The aim of this study was to provide a basis of knowledge of the anatomy of the venous plexuses in the lumbar spine both in anatomical slices and in MR images in order to help the analysis of these structures in MR images of living subjects. Four fresh cadaveric lumbar spines were studied after the injection of coloured gelatin mixed with gadolinium. The specimens were injected by an intraosseous technique. Axial and sagittal fat-saturated T1-weighted MR images were performed on the specimens. Thereafter, specimens were frozen and cut into 5-mm thick slices, three in the axial plane and one in the sagittal plane. All the components of the internal and external venous plexuses were identified on the MR images in correlation with the corresponding anatomic sections. The MR anatomy of the venous system of the lumbar spine is important as it has been implicated in many pathophysiological mechanisms and as it may also cause pitfalls in MR imaging.

Asunto(s)

Asunto(s)

RESUMEN

Fat suppression is commonly used in magnetic resonance (MR) imaging to suppress the signal from adipose tissue or detect adipose tissue. Fat suppression can be achieved with three methods: fat saturation, inversion-recovery imaging, and opposed-phase imaging. Selection of a fat suppression technique should depend on the purpose of the fat suppression (contrast enhancement vs tissue characterization) and the amount of fat in the tissue being studied. Fat saturation is recommended for suppression of signal from large amounts of fat and reliable acquisition of contrast material-enhanced images. The main drawbacks of this technique are sensitivity to magnetic field nonuniformity, misregistration artifacts, and unreliability when used with low-field-strength magnets. Inversion-recovery imaging allows homogeneous and global fat suppression and can be used with low-field-strength magnets. However, this technique is not specific for fat, and the signal intensity of tissue with a long T1 and tissue with a short T1 may be ambiguous. Opposed-phase imaging is a fast and readily available technique. This method is recommended for demonstration of lesions that contain small amounts of fat. The main drawback of opposed-phase imaging is unreliability in the detection of small tumors embedded in fatty tissue.

Asunto(s)

RESUMEN

MR imaging has become the diagnostic modality of choice for the evaluation of traumatic ligamentous and tendinous injures of the foot and ankle, occult bony trauma, and osteochondral lesions of the talus. This article reviews the current applications of MR imaging for the evaluation of sports-related injuries of the foot and ankle, including fractures, sprains, tendon injuries, and heel pain.

Asunto(s)

RESUMEN

PURPOSE: To determine the ability of MRI to detect the presence of crystals of calcium pyrophosphate in the articular cartilage of the knee. DESIGN AND PATIENTS: The MR studies of 12 knees (11 cases) were reviewed retrospectively and correlated with radiographs (12 cases) and the findings at arthroscopy (2 cases) and surgery (1 case). A total of 72 articular surfaces were evaluated. Radiographic, surgical or arthroscopic demonstration of chondrocalcinosis was used as the gold standard. Additionally, two fragments of the knee of a patient who underwent total knee replacement and demonstrated extensive chondrocalcinosis were studied with radiography and MRI using spin-echo T1-, T2- and proton-density-weighted images as well as two- and three-dimensional fat saturation (2D and 3D Fat Sat) gradient recalled echo (GRE) and STIR sequences. RESULTS: MRI revealed multiple hypointense foci within the articular cartilage in 34 articular surfaces, better shown on 2D and 3D GRE sequences. Radiographs showed 12 articular surfaces with chondrocalcinosis. In three cases with arthroscopic or surgical correlation, MRI demonstrated more diffuse involvement of the articular cartilage than did the radiographs. The 3D Fat Sat GRE sequences were the best for demonstrating articular calcification in vitro. In no case was meniscal calcification identified with MRI. Hyperintense halos around some of the calcifications were seen on the MR images. CONCLUSION: MRI can depict articular cartilage calcification as hypointense foci using GRE techniques. Differential diagnosis includes loose bodies, post-surgical changes, marginal osteophytes and hemosiderin deposition.

Asunto(s)

RESUMEN

Chylous cysts are in frequent entities which may have a variable pathogenesis. Their clinical and radiological presentation is fairly similar in each case report. Their CT appearance is very specific, but only histopathology can certify their etiology and their benign nature.

Asunto(s)