Nolan Karstaedt

MR imaging of anterior cruciate ligament repair.

Magnetic resonance (MR) imaging is an accurate means of analyzing disruptions of the native anterior cruciate ligament (ACL). Various techniques may be used to repair a disrupted ACL. A common repair is the Macintosh lateral-substitution over-the-top repair in which a strip of fascia lata from the iliotibial band is used as a “neoligament.” The results of 27 MR examinations of 17 athletes with this repair were analyzed to determine the appearance of the neoligament on MR. Thirteen of the 17 patients had returned to full athletic activity and four were capable of strenuous activity. Examinations were made at both 0.5 and 1.5 T in varied extents of external rotation from 0 to 20°, and at variable time intervals after surgery from 1 to nearly 40 months. Only two patients clinically required postrepair arthroscopy, but both had normal repairs. Neoligaments were classified as well-defined (n = 6 studies), ill-defined (n = 10), and not discernible (n = 11), based on clarity of appearance. Reasons for this variable appearance include the variable presence of fibrous and fatty tissue investing the neoligament. We conclude that the normal neoligament, unlike the normal active ACL, has a variable appearance, including nonvisualization on MR and that criteria used in evaluating the native ligament will be inadequate to assess the repair.

MR imaging of rhabdomyolysis

The use of magnetic resonance (MR) imaging in two cases of rhabdomyolysis, one resulting from prolonged muscle compression and one from electrical burns, is described. The involved muscles were clearly demonstrated with MR. Recognition and assessment of the extent of rhabdomyolysis are important since life-threatening sequelae including severe metabolic disorders are possible. In one case, spin-echo and inversion-recovery MR imaging provided greater detail of muscle abnormalities than did 99mTc-pyrophosphate radionuclide scanning. Both cases illustrate the usefulness of MR in evaluation of skeletal muscle disorders.

MRI findings of sciatic endometriosis

Endometriosis is a rare cause of sciatic mononeuropathy. We report a woman with cyclic, menstruation-related hip pain associated with right leg weakness and sensory loss. Examination and electrodiagnostic studies suggested sciatic nerve dysfunction. Magnetic resonance imaging (MRI) revealed abnormal signal consistent with endometriotic tissue in the region of the right sciatic nerve. The abnormal signal partially regressed after treatment of the endometriosis. This case further illustrates the utility of MRI in the assessment of rare pelvic disorders.

Magnetic Resonance Imaging of the Renal Mass

To compare the effectiveness of magnetic resonance imaging with that of excretory urography, retrograde pyelography, ultrasound, computerized tomography, angiography and venography 34 patients with renal masses, including 25 renal cell carcinomas, were examined on a 0.15 Tesla Picker 1100 magnetic resonance imager with multiple pulse sequences. Pathological proof was available for all cases except renal cysts, for which ultrasound or computerized tomographic findings were accepted. Differentiation of solid from cystic lesions was seen with magnetic resonance imaging, ultrasound and computerized tomography but not excretory urography. Tumor invasion of the renal vein and inferior vena cava was visualized in 7 patients by magnetic resonance imaging, ultrasound, computerized tomography and venography but not by excretory urography. Magnetic resonance T1 contrast scans best characterized renal masses, with good resolution of metastatic lymphadenopathy and renal cysts. Scans showing T2 contrast were best for identification of pseudocapsules in renal carcinoma, venous invasion by tumors and papillary adenocarcinoma. Advantages of magnetic resonance imaging include differentiation of solid masses from benign cystic lesions, and identification of major blood vessels and vascular invasion without administration of contrast medium. Disadvantages of magnetic resonance imaging are long imaging times and motion artifacts. Advances by the manufacturer in solving these problems will strengthen the role of magnetic resonance imaging in renal evaluation.

MR appearance of sternal hyperostosis

Sternal hyperostosis is characterized by prominent new bone formation and fibrosis with less pronounced areas of granulation tissue and round cell infiltration. In previously reported cases the process involved not only the sternum but adjacent bony areas as well. Depending upon the extent of disease, acquiring biopsy material for histologic analysis can be difficult. We report a case of sternal hyperostosis involving the sternum exclusively and extensively. Magnetic resonance imaging was useful in directing biopsy for optimal histologic yield. This unusual case of sternal hyperostosis is believed to be the result of an inflammatory process.

Nuclear magnetic resonance imaging.

Nuclear magnetic resonance imaging has reached the point at which it is clear that such images will have a definite role in clinical practice. This article reviews the basic physical principles of nuclear magnetic resonance imaging, its current uses in disorders of the central nervous system, and its potential future applications in this field. The technique is also compared with computed tomography and positron emission tomography. Because nuclear magnetic resonance imaging is still in its infancy and its potential is great, definitive statements on present clinical use are difficult. Continual change and expansion of the role of nuclear magnetic resonance imaging in clinical practice in the next few years should be the rule.

Unusual presentation of cholelithiasis on T1-weighted MR imaging.

Cholelithiasis usually appears on magnetic resonance as a signal void contrasting with the high signal of surrounding bile. We describe the appearance of two intraluminal gallstones as high-signal areas on a heavily T1-weighted scan and, based on infrared spectroscopic analysis of the stones, believe the fatty-acid content of the stones accounts for this unusual result. Increased focal intraluminal signal on strongly T1-weighted sequences does not, therefore, preclude a diagnosis of cholelithiasis.

Magnetic Resonance Imaging Evaluation of Immediate and Intermediate Changes in Kidneys Treated with Extracorporeal Shock Wave Lithotripsy

Magnetic resonance imaging (MRI) of kidneys was performed prior to extracorporeal shock wave lithotripsy (ESWLT), within 48 hours of treatment (immediate), and three months post-ESWL (intermediate) in 14 patients. Five patients underwent bilateral treatments for a total of 19 treated kidneys. With the pre-ESWL study serving as a control, immediate and intermediate examinations were evaluated for changes in renal volume, development of abnormalities in the corticomedullary junction (CMJ), development of intrarenal, subcapsular, or perinephric fluid, and alterations in the perinephric tissue and renal fascia. A statistically significant increase in renal volume occurred in the immediate post-ESWL period. This increase may have been secondary to parenchymal interstitial edema which resolved within three months. Thirty-two percent developed subcapsular bleeding and fascial and perinephric tissue prominence. All abnormalities identified on the immediate studies attributable to the ESWL treatment had resolved by the three-month study. No new cases of hypertension had developed within a three-month follow-up period.

Computed Tomography Versus Chest Radiography: Impact on Management of Patients with Lymphoma

To assess the influence of computed tomography of the thorax (CTT) in management of patients with lymphoma, we compared results of CTT and chest radiography (CXR) for 42 patients (65 examinations) with Hodgkins disease (HD) with 48 patients (57 examinations) with non-Hodgkin lymphoma (NHL). Six percent (7/122) of all CTs resulted in major changes in patient management (95% confidence interval = 2-12%). In four patients with HD, influential findings included of additional sites of lymphoma and clarification of x-ray results. In three patients with NHL (5%), management was altered as a result of identification of additional sites of lymphoma on CTT. Eleven percent of CTT examinations clarified equivocal CXR findings in NHL, and management was affected in two of these cases. Our findings suggest that CTT is valuable in clarifying equivocal CXR findings, and in staging or restaging patients for whom the detection of mediastinal adenopathy affect patient treatment.