Our objectives were to evaluate the reliability of MRI in distinguishing simple lipomas, lipoma variants, and well-differentiated liposarcomas (atypical lipomas) and to identify various imaging ...mimics of well-differentiated liposarcoma.
One hundred twenty-six consecutively imaged grossly fatty masses were retrospectively reviewed. MRI examinations, their prospective interpretations, and their corresponding pathology reports were compared to determine the reliability of MRI in distinguishing simple lipomas, lipoma variants, and well-differentiated liposarcomas.
The success of MRI in identifying well-differentiated liposarcomas among other fatty masses was as follows: sensitivity, 100%; specificity, 83%; accuracy, 84%; positive predictive value, 38%; and negative predictive value, 100%. MRI was 100% specific in the diagnosis of simple lipoma. Sixty-three percent of lesions considered suspicious for well-differentiated liposarcoma were actually simple lipomas (13%) and benign lipoma variants (50%), including chondroid lipoma (13%), osteolipoma (6%), hibernoma (6%), lipoleiomyoma (6%), angiolipoma (6%), and infarcted lipoma (13%).
Because of differences in treatment, prognosis, and long-term follow-up, it is important to preoperatively distinguish simple lipomas from well-differentiated liposarcomas. MRI is highly sensitive in the detection of well-differentiated liposarcomas and highly specific in the diagnosis of simple lipomas. However, when an extremity or body wall lesion is considered suspicious for well-differentiated liposarcoma, it is more likely (64%) to represent one of many benign lipoma variants.
To review retrospectively the magnetic resonance (MR) imaging findings and clinical information of patients with Parsonage-Turner syndrome (PTS).
The institutional review board did not require its ...formal approval or informed patient consent at the time of the study. However, the study was HIPAA compliant. The information in a computerized database of 2875 consecutive shoulder MR examinations was retrospectively reviewed. With use of key terms, the database software identified 81 examinations potentially associated with PTS. Both authors together reviewed the 81 imaging reports and the corresponding patients' medical records. In consensus, they made the diagnosis of PTS in 21 patients (two with bilateral involvement) on the basis of MR findings, electromyographic results, and clinical data. They also examined the data of an additional six patients (one with bilateral involvement) obtained from outside facilities. Ultimately, 30 shoulders of 27 patients (18 male, nine female; age range, 12-81 years; mean age, 41 years) were evaluated. The MR findings and clinical information (ie, regarding atrophy, pain, weakness, electromyographic results, neck and spine history, trauma, excessive overhead activity, recent surgery, vaccination, and illness) of all patients with PTS were reviewed. MR findings of diffuse high T2 signal intensity abnormality and fatty atrophy of muscles were evaluated to assess the pattern of nerve involvement. Structural causes (eg, ganglion cyst or other mass) of neurogenic high T2 signal intensity abnormality were excluded at MR imaging.
Twenty-nine (97%) of 30 shoulders had suprascapular nerve involvement; in 15 (50%) shoulders, the involvement was limited to this nerve. Fifteen (50%) shoulders had axillary nerve involvement; in only one (3%) shoulder, the involvement was limited to this nerve. One shoulder (3%) had subscapular nerve involvement. Nine (30%) shoulders demonstrated focal muscular atrophy. Eleven (41%) of 27 patients also underwent electromyography; all of these patients demonstrated neuropathies that matched the patterns of neurogenic high T2 signal intensity abnormality seen at MR imaging.
The suprascapular nerve was almost invariably involved (in 97% of shoulders) in patients with PTS. Axillary nerve involvement also was commonly observed (in 50% of shoulders). Subscapular nerve involvement was uncommon (in 3% of shoulders).
The purpose of this study was to evaluate the diagnostic accuracy of 3-T MRI versus 3-T MR arthrography for assessing labral abnormalities in the shoulder using arthroscopy as the gold standard.
...Forty-two patients (28 men, 14 women; mean age, 33 years) underwent MR arthrography and conventional MRI of the same shoulder. Two patients underwent bilateral shoulder examinations, for a total of 44 shoulder examinations. Twenty-two shoulders underwent arthroscopy. The results of arthroscopy were used as the reference standard. Three musculoskeletal radiologists prospectively and independently interpreted MRI and MR arthrography examinations. Differences in performance of conventional MRI and MR arthrography were analyzed for statistical significance by the two-tailed McNemar test.
Of the 22 arthroscopies performed, 26 labral tears were found in 18 shoulders and four shoulders were normal with respect to the labrum. There were 12 superior, nine posterior, and five anterior labral tears identified at arthroscopy. By consensus review, conventional MRI identified nine of 12 superior (sensitivity, 75%; specificity, 100%), seven of nine posterior (sensitivity, 78%; specificity, 92%), and three of five anterior (sensitivity, 60%; specificity, 94%) labral tears. MR arthrography identified nine of 12 superior (sensitivity, 75%; specificity, 100%), eight of nine posterior (sensitivity, 89%; specificity, 100%), and five of five anterior (sensitivity, 100%; specificity, 100%) labral tears.
Although the power of our preliminary study is small, the results suggest that intraarticular contrast material is helpful in diagnosing labral tears in the shoulder, particularly tears of the anterior labrum. Our preliminary results suggest that MR arthrography adds value for diagnosing labral tears in the shoulder compared with conventional MRI even at 3 T.
The Posterolateral Corner of the Knee Vinson, Emily N; Major, Nancy M; Helms, Clyde A
American journal of roentgenology (1976),
02/2008, Letnik:
190, Številka:
2
Journal Article
Recenzirano
The purpose of this article is to review the clinical importance and MRI appearances of injuries to the posterolateral corner of the knee.
Injuries to the posterolateral corner structures of the knee ...can cause significant disability due to instability, cartilage degeneration, and cruciate graft failure. Becoming familiar with the anatomy of this region can improve one's ability to detect subtle abnormalities and can perhaps lead to improvements in diagnosing and understanding injuries to this area.
New observations on meniscal cysts Anderson, Jada Jean; Connor, Gregory F.; Helms, Clyde A.
Skeletal radiology,
12/2010, Letnik:
39, Številka:
12
Journal Article
Recenzirano
Objective
The purpose of this study was to determine the incidence of meniscal cysts, assess the frequency of various magnetic resonance (MR) imaging characteristics, and emphasize radiographic ...observations not commonly reported.
Materials and methods
A total of 2,095 consecutive knee MR imaging reports from a 22 month period were retrospectively reviewed for the presence of meniscal cysts. Two musculoskeletal radiologists reviewed the cases where cysts were reported. A meniscal cyst was considered present if abnormally increased signal was identified within an enlarged meniscus (i.e., intrameniscal cyst) or if a loculated fluid-intensity lesion with a clear connection to the adjacent meniscus was identified (i.e., parameniscal cyst). Presence or absence of a meniscal tear, intrameniscal and parameniscal signal intensity, patient age, sex, location of meniscal cyst, presence of discoid meniscus, and size of the parameniscal cyst component were recorded. All knee imaging examinations were performed on a 1.5T MR unit. Imaging findings were correlated with arthroscopic reports when available.
Results
A total of 167 cases (8.0%) of meniscal cysts were diagnosed in 161 patients. Of the 167 cysts, 69 (41.3%) were located in the lateral meniscus and 98 (58.7%) in the medial meniscus. In 6 patients (3.7%), meniscal cysts were present in both menisci of the same knee. Twelve (7.2%) meniscal cysts were associated with discoid menisci. Ninety-seven (57.8%) meniscal cysts were associated with meniscal tears. Of the total number of meniscal cysts, 104 (62.3%) had a parameniscal cyst. An isolated intrameniscal cyst was present in 63 (37.7%) cases. One hundred (96%) of the parameniscal cyst components were isointense to fluid on T2-weighted FSE images. All cysts exhibited abnormal intrameniscal signal. Only 14 (8.4%) of the intrameniscal components were isointense to fluid on T2-weighted FSE images. The arthroscopic reports of 88 of the 161 (54.7%) patients were available for review and correlation. A tear extending to the articular surface of the meniscus was reported to be present in 74 of the 88 (84%) arthroscopic examinations.
Conclusions
Knowledge of the spectrum of findings and the relative frequency of various MR imaging characteristics as well as common potential pitfalls is important to the accurate diagnosis and management of mensical cysts. In particular, controversy exists as to the incidence of articular surface tears in association with meniscal cysts, with some authors reporting greater than 98% correlation with tears. Only 58% of cysts were associated with an articular surface tear. Ninety six percent of the parameniscal signal was isointense to fluid, only 8% of the intramensical signal was isointense to fluid.
The purpose of our study was to describe the MRI findings in the posterior cruciate ligament (PCL) analogous to mucoid degeneration in the anterior cruciate ligament (ACL); to correlate MRI findings ...in the PCL with ligamentous stability; to differentiate the PCL tram-track appearance from the appearance of PCL tears; and to emphasize the coexistence of PCL and ACL mucoid degeneration, cruciate ganglia, and meniscal cysts.
The tram-track PCL appearance commonly coexists with ACL mucoid degeneration; ganglia; and, less frequently, meniscal cysts. Both PCL tears and MRI findings suggestive of PCL mucoid degeneration show ligament thickening and increased PCL signal intensity. Tram-track PCLs are usually asymptomatic and typically have no ligamentous instability.
The purpose of this study was to assess the prevalence of radial meniscal tears at arthroscopy and the ability of MRI to detect radial tears preoperatively. In addition, the ability of four ...radiologic signs to detect radial tears was assessed. Those signs are the truncated triangle, cleft, marching cleft, and ghost meniscus signs.
Arthroscopy of the knee was performed by a single orthopedic surgeon on 196 consecutive patients. The surgeon noted each radial tear he encountered. The MR images that were obtained at our institution were reviewed, whereas those patients who were imaged elsewhere were excluded. The preoperative MRI reports were reviewed to assess the ability to prospectively identify radial meniscal tears. In addition, a retrospective analysis of the MRI studies was performed by two radiologists in which four radiologic signs were applied to detect radial tears.
Twenty-nine patients (15%) had radial tears at arthroscopy. Eighteen of the 29 patients had their imaging performed at our institution and were selected for review. There were 19 radial tears found at surgery. Seven (37%) of the 19 tears were identified as radial prospectively. Retrospectively, using the four signs for radial tears, reviewers identified 17 (89%) of 19 radial tears.
A more accurate preoperative diagnosis may be rendered using the four described signs to detect radial tears, thus allowing informative preoperative counseling and consideration of new therapies that are available for radial meniscal repair.
There is little in the radiology literature regarding the MRI appearance of a torn posterior cruciate ligament (PCL). The purpose of this study was to describe the MRI appearance of surgically proven ...PCL tears and to emphasize previously unreported signs.
The PCL is usually injured as the result of stretching deformation; on MRI, the ligament maintains continuity as a single structure with apparent thickening. On sagittal T2-weighted images, an anteroposterior diameter of 7 mm or more is highly suggestive of a torn PCL. Increased intrasubstance signal intensity in the PCL on proton-density images with lower signal intensity on T2-weighted images is another common feature.
Objective
To describe imaging findings in patients with synovial fringe (SF) syndrome of the elbow and to compare with a control population.
Materials and methods
Nine patients (5 men, 4 women) whose ...mean age was 35.7 years were diagnosed with SF syndrome and had undergone preoperative elbow MRI. The radiohumeral (RH) plica was assessed for thickness, cross-sectional area, coverage of one third or more of the radial head, blunting of the free edge, and T2 signal intensity abnormality. Other abnormalities of the RH joint were also assessed, including adjacent articular cartilage defects, subcortical bone marrow signal abnormality in the capitellum, and synovitis. Results were compared with 15 control patients who were asymptomatic laterally and posteriorly.
Results
Mean thickness and cross-sectional area of the RH plica were 1.8 mm and 19.4 mm
2
respectively in controls, compared with 2.5 mm and 21.9 mm
2
respectively in symptomatic patients. No statistically significant differences in the distribution of the mean thickness or cross-sectional area of the RH plica were found between the two groups. However, 67% of SF syndrome patients had a RH plica thickness greater than 2.6 mm compared with only 13% of controls (
p
= 0.021). Other abnormalities of the RH plica occurred more frequently in patients with SF syndrome compared with controls, but were not statistically significant.
Conclusion
In patients presenting with posterolateral pain or mechanical symptoms in the elbow, RH plica thickness greater than 2.6 mm on elbow MRI examinations may help identify patients with SF syndrome.
