Magnetic resonance imaging of posterior cruciate ligament injuries: assessment of healing.

This study evaluated posterior cruciate ligament (PCL) healing using magnetic resonance imaging (MRI). Forty knees with acute PCL injuries underwent acute and follow-up (>6 months) MRI examinations. Twenty-three knees had isolated injuries, and 17 knees had associated ligament damage. The initial MRI scans showed 22 high-grade injuries with complete disruption, 14 with midgrade injuries with extensive edema on T2 images with some bridging fibers present, and 4 patients had low-grade injuries. At a mean time of 3.2+/-1.3 years after the initial MRI, the follow-up MRIs revealed the PCL healed with continuity in all of the low-grade and mid-grade injuries, and in 19 of 22 high-grade injuries. Of the 19 high-grade PCL tears that healed, 4 healed with normal contour and 15 were continuous with altered morphology at follow-up. Of 11 high-grade PCL-injured knees with associated ligament damage, only 1 PCL failed to regain continuity. The 3 PCLs that did not regain continuity were in 2 patients with isolated injuries and 1 patient with associated anterior cruciate and medial collateral ligament injuries. These results demonstrate that most nonoperatively treated PCL injuries, even in association with other knee ligament damage, can heal with continuity.

MR imaging of anterior cruciate ligament injuries.

MR imaging has become the imaging modality of choice to evaluate the integrity of the anterior cruciate ligament (ACL). This article discusses the normal anatomy of the ACL and the clinical diagnosis of ACL disruption. The MR imaging appearance of chronic and acute ACL injuries, and the relative value of primary and secondary signs in injury diagnosis are reviewed. The clinical value of MR imaging in the evaluation of the ACL-deficient knee is also discussed.

Anterior translocation of the tibia at MR imaging: a secondary sign of anterior cruciate ligament tear.

The authors evaluated measurement of the degree of anterior subluxation ("translocation") of the tibia in regard to the femur as a predictor of anterior cruciate ligament (ACL) tear. Eighty-nine magnetic resonance (MR) imaging studies of patients with either an arthroscopically confirmed intact (n = 29), acutely torn (n = 27), or chronically torn (n = 33) ACL were retrospectively reviewed. The degree of translocation was measured on hard-copy images by using two methods. Buckling of the posterior cruciate ligament (PCL) was also evaluated. Anterior tibial translocation, when measured at the midsagittal plane of the lateral femoral condyle with regard to a plane parallel to the cephalocaudal axis of the image, was a relatively specific indicator of ACL disruption. Subluxation of 5 mm or more had 58% sensitivity, 93% specificity, and 69% accuracy for an ACL tear. All knees with subluxation of 7 mm or more had torn ACLs. Buckling of the PCL was less sensitive and less accurate than anterior translocation as an indicator of ACL disruption.

MR imaging of meniscal tears: narrow versus conventional window width photography.

Narrow window width photography of magnetic resonance (MR) images of knee menisci is promoted as a useful tool in the detection of meniscal tears. To assess the diagnostic efficacy of this method, conventional and narrow window width MR images of 48 patients (96 menisci, 37 tears) were interpreted by two experienced observers. Images were graded on a five-point scale to enable receiver operating characteristic (ROC) curve analysis. The ROC curves constructed from the conventional window width interpretations were similar to those of the narrow window width interpretations for both observers. It was not possible to prove that the areas under the two curves were significantly different. This suggests that there is no globally significant improvement in the detection of meniscal tears when narrow window width images are used for interpretation.

The prevalence and significance of cyst-like changes at the cruciate ligament attachments in the knee.

Approximately 1% of the total population referred for magnetic resonance imaging (MRI) of the knee at our facility have cystic changes at or near the attachment of the anterior or posterior cruciate ligaments (ACL, PCL). Cases were collected prospectively from a group of 1710 consecutive knee MR examinations, and a retrospective study analyzed the typical appearance of these cysts and any associated findings. Although most of the cysts were an incidental finding, two were associated with significant adjacent marrow edema.

Acute and chronic tears of the anterior cruciate ligament: differential features at MR imaging.

To evaluate the differential features of acute and chronic tears of the anterior cruciate ligament at magnetic resonance (MR) imaging, the authors performed a retrospective evaluation of findings in 81 MR examinations correlated with results at arthroscopy. Intact anterior cruciate ligaments (ACLs) were present in 29 patients; acute complete ACL tears, in 22; and chronic complete ACL tears, in 30. Acute tears were accurately distinguished from intact ligaments and were characterized by the presence of edema. Chronic tears had a more variable appearance: Nine (30%) were depicted at MR as intact bands with low signal intensity that bridged the expected origin and insertion of the ACL. This appearance is likely due to the presence of bridging fibrous scars within the intercondylar notch. Five of these nine cases were correctly characterized as chronically torn because of the presence of focal angulation. In four of these nine cases the scarred fragments produced a relatively straight band that mimicked an intact ligament. Although chronic and acute ACL tears usually have distinct findings at MR, a chronic tear will occasionally be difficult to distinguish from an intact ligament.

MR imaging of the knee: pseudotear of the lateral meniscus caused by the meniscofemoral ligament.

Sagittal MR images of the knee often show a linear band of increased signal in the medial aspect of the posterior horn of the lateral meniscus that can be confused with a meniscal tear. This pseudotear is due to the meniscal insertion of the meniscofemoral ligament. To study the normal appearance of the medial aspect of the posterior horn of the lateral meniscus, we analyzed 109 MR examinations and correlated the findings with the results of arthroscopy. The meniscofemoral ligament was visualized in 54 cases (50%), and in 42 cases (39%) it caused the appearance of a pseudotear on sagittal images. The pseudotear had one of two orientations. The most common (35/42) was an oblique orientation coursing from the superior surface posteriorly and inferiorly. The other (7/42) was a more vertical orientation parallel to the base of the meniscus. Knowledge of the characteristic location and orientation of the meniscofemoral ligament should help to distinguish it from a true meniscal tear on MR images.

MR diagnosis of pancreatic transplant rejection.

To determine the role of MR imaging in the assessment of pancreatic transplant rejection, we prospectively obtained 13 MR scans in nine transplant patients. The presence of rejection was verified pathologically by pancreatic transplant biopsies in five patients. In two additional patients, rejection was proved by concordant renal transplant biopsy as well as by compatible clinical and laboratory data. In the remaining two patients, in whom no biopsy was done, clinical and laboratory data showed no evidence of rejection. The mean T2 of the seven pancreata undergoing rejection was significantly elevated (86 msec) compared with the mean T2 of the two transplants not undergoing rejection (59 msec) (p less than .002). These preliminary results suggest that MR may be useful in the noninvasive diagnosis of pancreatic rejection.

State-of-the-art barium examination in opportunistic esophagitis.

This report presents a comparison of state-of-the-art esophagography and endoscopy in the diagnosis of pathologically proven esophagitis. The modern multiphasic esophagogram is shown to have a sensitivity of 92% for the detection of opportunistic esophagitis in the immunocompromised patient. State-of-the-art esophagography provides a sensitive and inexpensive method for investigating patients in whom opportunistic esophagitis is suspected and for monitoring their response to therapy.

Enteroclysis in partial small bowel obstruction.

In a 5 year period, 56 patients with suspected partial small bowel obstruction were evaluated by enteroclysis or the antegrade small bowel enema. Mechanical partial obstruction was diagnosed by enteroclysis in 38 of the patients, 24 of whom required surgery. The diagnosis by enteroclysis was confirmed in 23 of the patients. In the single patient with "false-positive" enteroclysis, the obstruction had been interpreted as minimal. The thirteen remaining patients were managed conservatively. The possibility of significant mechanical obstruction was excluded by enteroclysis in 19 patients. There were no complications associated with the procedure. Enteroclysis is a safe, rapid, and accurate method for the evaluation of patients with partial small bowel obstruction.