Long-term forest monitoring reveals constant mortality rise in European forests.

European forests are an important source for timber production, human welfare, income, protection and biodiversity. During the last two decades, Europe has experienced a number of droughts which have been exceptional within the last 500 years, both in terms of duration and intensity. These droughts seem to leave remarkable imprints on the mortality dynamics of European forests. However, systematic observations on tree decline, with emphasis on a single species, has been scarce so far so that our understanding of mortality dynamics and drought occurrence is still limited at a continental scale. Here, we make use of the ICP Forest crown defoliation dataset, permitting us to retrospectively monitor tree mortality for all major conifers, major broadleaves, as well as a pooled dataset of minor tree species in Europe. In total, we analysed more than three million observations gathered during the last 25 years and employed a high-resolution drought index which can assess soil moisture anomaly based on a hydrological water-balance and runoff model. We found overall and species-specific increasing trends in mortality rates, accompanied by decreasing soil moisture. A generalized linear mixed model identified a previous-year soil moisture anomaly as the most important driver of mortality patterns in conifers, but the response was not uniform across the numerous analysed plots. We conclude that mortality patterns in European forests are currently reaching a concerning upward trend which could be further accelerated by global change-type droughts in the near future.

Acetabular paralabral cyst: an uncommon cause of sciatica.

The association between tears of the acetabular labrum and paralabral cysts has been well documented, and magnetic resonance imaging (MRI) has been shown to be the most accurate noninvasive method of depicting not only the normal anatomic structures of the hip, but also the common pathologic processes such as labral tears and paralabral cysts. We present the case of an acetabular paralabral cyst that resulted in clinically symptomatic compression of the sciatic nerve.

Medial patellofemoral ligament injury following acute transient dislocation of the patella: MR findings with surgical correlation in 14 patients.

PURPOSE: The purpose of this study was to determine the accuracy of MRI in determining both the extent and the location of injury to the medial patellofemoral ligament (MPFL). METHOD: MR findings were compared to the surgical results of 14 consecutive patients who experienced transient patellar dislocation. Two musculoskeletal radiologists, blinded to the surgical results, retrospectively reviewed the MR studies, and a consensus reading was obtained. RESULTS: Surgery demonstrated complete disruption of the MPFL in 7 of 14 patients (50%), with stretching or partial tearing of the MPFL in the remaining 7 (50%) patients. MRI was 85% sensitive and 70% accurate in detecting MPFL disruption. Vastus medialis obliquus muscle elevation was present in 12 of 14 (85%). CONCLUSION: MRI accurately depicts both the extent and the location of MPFL injury following transient patellar dislocation and can therefore play a significant role in directing surgical management of these patients.

Autogenous osteochondral "plug" transfer for the treatment of focal chondral defects: postoperative MR appearance with clinical correlation.

OBJECTIVE: To describe the MR appearance following autogenous osteochondral "plug" transfer for the treatment of focal chondral defects of the knee. DESIGN AND PATIENTS: Twenty-nine 1.5-T MR knee studies including dynamic gadolinium enhancement were performed on 21 patients following autogenous osteochondral "plug" transfer. Three musculoskeletal radiologists retrospectively reviewed images to evaluate graft and donor site appearance and MR findings were correlated with clinical outcomes. RESULTS: MR images demonstrated graft protuberance (n=12/21; range 1-2 mm), depression (n=2/21; range 1 mm), and surface incongruity: mild (n=17/21), moderate (n=2/21), marked (n=1/21). The T2 signal of graft cartilage was similar to that of adjacent cartilage in 25 of 29 examinations, and increased in four. Graft cartilage thickness relative to adjacent cartilage was <50% in six patients, 50-100% in 15. Graft enhancement in bone was absent at 2 weeks, but present at between 4 and 6 weeks following surgery. All patients had clinical follow-up examinations and knee outcome survey scores were obtained in 15 patients with follow-up greater than 3 months after surgery. All patients demonstrated the expected short-term progressive clinical improvement. CONCLUSION: MR images reveal a wide range of appearances following osteochondral "plug" transfer. Minor variations in graft orientation and surface congruity do not result in adverse clinical outcome in the short term.

MR imaging of the posterior cruciate ligament graft: initial experience in 15 patients with clinical correlation.

PURPOSE: To describe the magnetic resonance (MR) appearance of the posterior cruciate ligament (PCL) graft in the 1st postoperative year and to correlate the MR findings with clinical examination findings. MATERIALS AND METHODS: Nineteen MR examinations were performed in 15 patients (with 15 grafts) 1-33 months after PCL reconstruction. Results of clinical follow-up were available in 14 patients. Graft shape and thickness were recorded, and intrasubstance signal intensity at T2-weighted imaging was graded. The MR findings were correlated with the time between surgery and clinical examination. RESULTS: At MR imaging, 13 grafts appeared intact, one could not be assessed owing to hardware artifact, and one initially appeared disrupted. Graft thickness was 7-19 mm. There was no significant difference between graft thickness versus time since surgery and signal intensity versus time since surgery (P =.14). In two of three patients who underwent sequential MR examinations, graft thickness and intrasubstance signal intensity decreased as the time between reconstruction and MR imaging increased. Two of 14 patients who underwent physical examination had a posterior drawer, and one also had an anterior cruciate ligament graft tear. Both patients with knee instability demonstrated intact PCL graft fibers at MR imaging. There was no correlation between knee stability and graft thickness, signal intensity, or shape. CONCLUSION: After PCL reconstruction, MR imaging in the 1st year depicts a thickened graft with increased signal intensity. There does not appear to be a relationship between clinical stability and findings at MR imaging.

MR imaging of meniscal cysts: incidence, location, and clinical significance.

OBJECTIVE: The purpose of this study was to determine the incidence of medial versus lateral meniscal cysts as seen on MR imaging. MATERIALS AND METHODS: A total of 2572 knee MR imaging reports were retrospectively reviewed for the presence of meniscal tears and cysts. Two musculoskeletal radiologists reviewed all images with reported cysts. The type and location of meniscal tear and the presence and location of meniscal cysts were recorded. RESULTS: A total of 1402 meniscal tears were reported in 2572 MR examinations (922 [66%] of 1402 in the medial compartment; 480 [34%] of 1402 in the lateral compartment). Meniscal cysts were present in 109 (4%) of 2572 knees. Of the 109 cysts, 72 (66%) were in the medial compartment, and 37 (34%) were in the lateral compartment. Meniscal cysts were found in association with 72 (7.8%) of the 922 medial meniscal tears and 37 (7.7%) of the 480 lateral meniscal tears. Meniscal cysts showed direct contact with an adjacent meniscal tear in 107 (98%) of 109 cases, with the tear showing a horizontal component in 96 (90%) of 107 cases. CONCLUSION: Meniscal cysts occur almost twice as often in the medial compartment as in the lateral compartment. Medial and lateral tears occur with the same frequency. These findings, when viewed in the context of the historical literature on meniscal cysts, suggest that MR imaging detects a greater number of medial meniscal cysts than physical examination or arthroscopy, and that MR imaging can have an important impact on surgical treatment of patients.

Imaging of osteochondral injuries.

Acute injuries can produce fragments consisting of cartilage alone or cartilage and underlying bone. A purely cartilaginous fragment creates no direct radiographic abnormalities, whereas one containing calcified cartilage and bone appears as a radiodensity. The advent and refinement of MR imaging have led to the detection of occult injuries of subchondral bone and cartilage that can escape identification on routine radiographic analysis. The available data appear to indicate a substantial role for MR imaging in the analysis of lesion stability in cases of osteochondritis dissecans; however, further studies are required to determine its advantages over other methods, in particular, arthroscopy. Indirect evidence of cartilage abnormality on MR images relates to the identification of fluid at the interface between the fragment and the parent bone. The MR imaging technique influences dramatically whether such fluid is identified. MR arthrography employing the intra-articular injection of gadolinium compounds can be advantageous in the delineation of the chondral surface and in the detection of intraarticular bodies. Optimally, MR imaging would allow direct analysis of the cartilage surface, and specific imaging sequences that are most suited to this analysis are still evolving.

Radiographic imaging of musculoskeletal neoplasia.

BACKGROUND: Imaging is an integral part of the diagnosis, staging and evaluation of outcomes for bone and soft-tissue neoplasms. Each of the available imaging tools has a different role. METHODS: The authors reviewed the efficacy of the current imaging modalities in the diagnosis, staging, and follow-up of patients with musculoskeletal neoplasia. RESULTS: Plain-film radiography remains the gold standard in the differential diagnosis of bone lesions. Bone scintigraphy is an excellent screening modality, and computed tomography is especially useful in evaluating lesions of the axial skeleton. The superior soft-tissue resolution and multiplanar capabilities achieved with magnetic resonance imaging, however, has replaced the need for CT scans in many cases. CONCLUSIONS: The technological advances seen in recent years in all areas of imaging have improved the capabilities of these modalities to assist in the diagnosis, definition of tumor extent, and accurate staging of musculoskeletal tumors.

Subtendinous bone marrow edema patterns on MR images of the ankle: association with symptoms and tendinopathy.

OBJECTIVE: We sought to describe a pattern of subtendinous bone marrow edema on MR images of the ankle and to determine if there is an association with location of symptoms and overlying tendinopathy. MATERIALS AND METHODS: At 1.5 T, 141 MR examinations of the ankle (116 clinical examinations of patients with chronic pain, 25 of asymptomatic control patients) were performed using T1-weighted, proton density-weighted fast spin-echo, and T2-weighted fat-suppressed fast spin-echo sequences. Images were retrospectively reviewed by two musculoskeletal radiologists for presence of bone marrow edema occurring in a subcortical location associated with the course of the medial or lateral tendon groups, as well as focal thickening or increased T2 signal within the tendons. These findings were correlated with clinical information regarding symptom location. The association of subtendinous marrow edema with tendinopathy and symptom location was statistically analyzed. RESULTS: Subtendinous bone marrow edema was present at 26 sites on 24 ankle MR examinations (17%) (at the medial malleolus [n = 17] associated with the posterior tibialis tendon, at the lateral malleolus [n = 6] and the calcaneus [n = 2] associated with the peroneus longus and brevis tendons, and at the cuboid [n = 1] associated with the peroneus longus tendon). These subtendinous bone marrow edema patterns were significantly associated with overlying tendon abnormality medially (p = 0.001) and laterally (p = 0.001), and with symptoms medially (p = 0.0016) but not laterally (p = 0.078). CONCLUSION: On MR images of the ankle, bone marrow edema localized in a subtendinous location is associated with overlying tendinopathy medially and laterally and with ankle pain medially.

Magnetic resonance imaging at different time periods following hamstring harvest for anterior cruciate ligament reconstruction.

PURPOSE: The purpose of this study was to evaluate the magnetic resonance imaging (MRI) appearance of the hamstring graft harvest site after harvesting the hamstring tendons to reconstruct a torn anterior cruciate ligament (ACL). TYPE OF STUDY: Case series. METHODS: We performed MRI on 21 patients who had previously undergone hamstring harvest and ACL reconstruction. Twenty of the patients (7 female and 13 male; mean age, 37 years; range, 16 to 84 years), all volunteers, were selected from a series of 45 ACL reconstructions performed by the senior author during a 20-month period. Another patient, a 32-year-old man, underwent ACL reconstruction elsewhere 32 months before. Both the semitendinosus and gracilis tendons were harvested in all cases. All MRIs were obtained on a 1.5-T magnet and were prospectively evaluated by 2 experienced musculoskeletal radiologists who were blinded to the time interval between graft harvest and MRI. RESULTS: Two weeks after graft harvest, MRI showed ill-defined intermediate signal on T1-weighted images and increased signal on T2-weighted images, consistent with fluid in the harvest site, with no discernable tendon. At 6 weeks, structures were seen at the level of the superior pole of the patella that had morphology and signal characteristics similar to native tendon. By 3 months, structures with normal morphology and signal characteristics were seen to the level of the joint line, and by 12 months, to the level of 1 to 3 cm above that of the tibial attachment. At 32 months, the tendons appeared on MRI to normalize to a level of 1 to 2 cm above their tibial attachment. CONCLUSION: Following hamstring tendon harvest, MRI demonstrates an apparent regeneration of tendons beginning proximally and extending distally over time.

Bone contusion patterns of the knee at MR imaging: footprint of the mechanism of injury.

Bone marrow contusions are frequently identified at magnetic resonance imaging after an injury to the musculoskeletal system. These osseous injuries may result from a direct blow to the bone, from compressive forces of adjacent bones impacting one another, or from traction forces that occur during an avulsion injury. The distribution of bone marrow edema is like a footprint left behind at injury, providing valuable clues to the associated soft-tissue injuries. Five contusion patterns with associated soft-tissue injuries occur in the knee: pivot shift injury, dashboard injury, hyperextension injury, clip injury, and lateral patellar dislocation. The classic bone marrow edema pattern seen following the pivot shift injury involves the posterolateral tibial plateau and the midportion of the lateral femoral condyle. Edema occurs in the anterior aspect of the proximal tibia following the dashboard injury. Hyperextension results in the "kissing" contusion pattern involving the anterior aspect of the proximal tibia and distal femur. The clip injury results in a prominent area of edema involving the lateral femoral condyle and a smaller area of edema involving the medial femoral condyle. Finally, lateral patellar dislocation results in edema involving the inferomedial patella and anterior aspect of the lateral femoral condyle. In many instances, the mechanism of injury can be determined by studying the distribution of bone marrow edema, which then enables one to predict with accuracy the specific soft-tissue abnormalities that are likely to be present.

Imaging techniques for the evaluation of glenohumeral instability.

The ability to image lesions associated with glenohumeral instability has evolved significantly over the past 2 decades. In the past, several imaging techniques ranging from conventional radiography to computerized axial arthrography and, most recently, to magnetic resonance imaging have been used to depict various labral abnormalities. In most instances, conventional radiography remains the initial imaging study for evaluating the patient with persistent shoulder pain and instability. Recently, however, magnetic resonance arthrography has been firmly established as the imaging modality of choice for demonstrating specific soft tissue abnormalities associated with glenohumeral instability. This article will review the role of various imaging modalities including conventional radiography, conventional arthrography, computerized axial arthrography, magnetic resonance imaging, and magnetic resonance arthrography. Emphasis will be placed on the role of magnetic resonance arthrography as it pertains to the lesions associated with glenohumeral instability. A thorough discussion of the appearance of normal anatomic structures, anatomic variations that mimic abnormality, and the various lesions associated with glenohumeral instability will be provided.

Direct MR arthrography of the shoulder: is exercise prior to imaging beneficial or detrimental?

PURPOSE: To define the beneficial and detrimental effects of adding exercise to direct magnetic resonance (MR) shoulder arthrography. MATERIALS AND METHODS: Direct, intraarticular, gadolinium arthrography of the shoulder was performed in 41 patients, who underwent 1.5-T MR imaging before and after 1 minute of arm swinging. Fourteen milliliters of dilute gadolinium solution was injected. Two readers blinded to exercise independently graded the randomly distributed images with a five-point scale for capsular contrast material resorption; extraarticular contrast material leakage; rotator cuff, glenoid labrum, and anterior capsule conspicuity; and partial-thickness or full-thickness rotator cuff tear and labral tear detectability. The sign test was performed to evaluate the significance of differences between preexercise and postexercise grading for each reader. A second review was performed, with direct side-by-side comparison of preexercise and postexercise images. RESULTS: There was evidence of increased capsular resorption after exercise but no alteration in the depiction of the rotator cuff tendons or glenoid labrum. There was no significant extraarticular contrast material leakage after exercise and no alteration in depiction of the anterior capsule. There was no difference in the detectability of rotator cuff or labral tears. CONCLUSION: Exercise with direct shoulder MR arthrography has no beneficial or detrimental effect on image quality or on the depiction of rotator cuff or labral tears.

Association of intramuscular cysts of the rotator cuff with tears of the rotator cuff: magnetic resonance imaging findings and clinical significance.

Cystic lesions that arise adjacent to the shoulder have been reported in association with labral tears or as an unusual manifestation of massive rotator cuff tears. The purpose of this study was to define the relationship between intramuscular cysts of the rotator cuff and tears of the rotator cuff. Thirteen cases of intramuscular cysts of the rotator cuff were identified on magnetic resonance imaging of the shoulder and analyzed retrospectively along with the clinical data. Surgical findings were retrospectively reviewed in 5 patients who underwent follow-up arthroscopy. This series shows that intramuscular cysts of the rotator cuff are associated with small, full-thickness tears or partial undersurface tears of the rotator cuff. These cysts are easily identified on T2-weighted sequences and, when present, should always prompt a thorough search for associated rotator cuff pathology.

Oblique meniscomeniscal ligament: another potential pitfall for a meniscal tear--anatomic description and appearance at MR imaging in three cases.

Three patients with an arthroscopically proved normal variant, the oblique meniscomeniscal ligament, underwent prospective magnetic resonance (MR) imaging of the knee. In the first case, the ligament was misinterpreted as a displaced flap tear of the posterior horn of the lateral meniscus. In the two subsequent cases, the ligament was identified correctly at MR imaging as the oblique meniscomeniscal ligament.

Paralabral cyst: an unusual cause of quadrilateral space syndrome.

A paralabral cyst arising from a detached inferior glenoid labral tear was shown by magnetic resonance imaging (MRI) to dissect into the quadrilateral space, resulting in a compressive neuropathy of the axillary nerve. Three consecutive MRI examinations were performed over a 5-year period in a 47-year-old man with a long history of worsening shoulder pain. The MRI examinations revealed a slowly enlarging paralabral cyst extending into the quadrilateral space with progressive atrophy of the teres minor muscle.

Fracture of the lateral process of the talus: appearance at MR imaging and clinical significance.

The case of a 59-year-old man with chronic lateral ankle pain following an inversion injury is presented. MR imaging performed to evaluate for soft tissue injury revealed an unsuspected fracture of the lateral process of the talus. The patient underwent surgical exploration of the fracture with debridement of adjacent loose bodies and is currently undergoing aggressive physical rehabilitation.

The glenolabral articular disruption lesion: MR arthrography with arthroscopic correlation.

OBJECTIVE: The purpose of this study was to describe the MR arthrography appearance of the glenolabral articular disruption (GLAD) lesion. Proper diagnosis of this lesion is important because it can be a source of persistent shoulder pain that requires surgical repair and because it is often difficult to diagnose clinically. MATERIALS AND METHODS: Findings on MR arthrography were retrospectively correlated with the clinical histories and physical examination findings of six patients in whom we saw the typical appearance of the GLAD lesion. Four of these patients underwent follow-up arthroscopy that included surgical proof of GLAD lesions. RESULTS: Five of the six patients had a documented glenohumeral impaction injury associated with an abducted externally rotated shoulder. All six patients had persistent shoulder pain, but their shoulders were stable during routine examination. In all patients, MR arthrography showed a superficial tear of the anteroinferior labrum with an adjacent articular cartilage injury. The torn labrum remained firmly attached to the anterior scapular periosteum, and contrast material was seen to extend into the labral tear and cartilaginous defect. CONCLUSION: The MR arthrography findings of GLAD lesions include a nondisplaced tear of the anteroinferior labrum with an adjacent chondral injury. The pattern of chondral injury can range from a cartilaginous flap tear to a depressed osteochondral injury of the articular cartilage and underlying bone.