Iron-based second-sphere contrast agents for magnetic resonance imaging: development of a model system and evaluation of iron (III) tris (tironate) complex in rats.

RATIONALE AND OBJECTIVES: Iron(III) complexes have been developed as magnetic resonance (MR) contrast agents based on the use of ligands capable of providing coordinative saturation at iron and allowing the second-sphere hydrogen bonding of water molecules. METHODS: Studies of solution-phase binding of a probe ion to a diamagnetic metal catecholate complex and molecular orbital calculations were performed. R1 values were determined. Toxicity studies of iron(III) tris(tironate) were conducted with rats. Excretion studies were performed by analysis of urine samples. MR measurements were made. RESULTS: Second-sphere coordination of a probe ion to a metal catecholate complex occurred in solution. Molecular orbital calculations suggested flexibility in design. Iron(III) tris (catecholate) complexes were shown to have high R1 values. Images of the kidneys and liver showed dose-dependent enhancement in T1-weighted images. The onset of toxicity was at approximately 0.30 mmol/kg. Urine analysis indicated essentially complete clearance (0.1-0.2 mmol/kg) within 24-48 hours. CONCLUSION: Interactions between water molecules and basic sites within a paramagnetic metal-ligand complex allow for application of suitable complexes as T1 agents.

MR demonstration of anomalous muscles about the volar aspect of the wrist and forearm.

Magnetic resonance (MR) examination of 42 normal wrists was performed for evaluation of anomalous musculature. A total of 23 muscle variations were found. An accessory abductor digiti minimi was found in 10 wrists (24%), an absent palmaris longus was found in seven wrists (16%), a muscular palmaris longus tendon was found in three wrists (7%), a muscular flexor digitorum superficialis was found in two wrists (5%), and an aberrant lumbrical muscle originating from within the carpal tunnel was found in one wrist (2.4%). Such muscle variations can be distinguished by MR from other mass lesions at the wrist and a knowledge of their frequency, appearance, and location can be of help in this regard.

A 45-year-old woman with right shoulder pain.

The following case is presented to illustrate the roentgenographic and clinical findings of a condition of interest to the orthopedic surgeon. Initial history, physical findings, and roentgenographic examinations are found on the first page. The final clinical and roentgenographic differential diagnoses are presented on the following pages.

Comparison of bone contusion seen by MRI in partial and complete tears of the anterior cruciate ligament.

OBJECTIVE: Bone contusions are frequently found in association with complete tears of the anterior cruciate ligament (ACL) and can be a helpful secondary sign in diagnosis. We compare the frequency, location, and significance of bone contusions in complete and partial ACL tears. MATERIALS AND METHODS: Twenty-nine patients with complete and 42 patients with incomplete tears of the ACL were examined by MRI for the presence of accompanying bone contusions within 1 month of injury. RESULTS: Bone contusions were found in 72% of the complete ACL tears but in only 12% of the partial tears. Of the partial ACL tears with accompanying contusions, 80% were high grade injuries that eventually went on to complete rupture within 6 months. Only 16% of the partial ACL injuries without bone contusion progressed to complete rupture at 1-2 year follow-up. There was no difference between the bone contusions of partial and complete tears in terms of general appearance and location. They were predominantly in the lateral compartment (90%) and had a specific predilection for the mid portion of the lateral femoral condyle and the posterior portion of the lateral tibial plateau, often occurring in tandem. CONCLUSION: Bone contusions occur with much less frequency in partial ACL tears than in complete tears but their presence in partial rupture favors a high grade tear that is likely to become complete.

MR demonstration of an anomalous muscle in a patient with coexistent carpal and ulnar tunnel syndrome. Case report and literature summary.

An aberrant muscle is demonstrated by magnetic resonance (MR) imaging in a patient presenting with focal wrist swelling and compression neuropathy of median and ulnar nerves following 4 months of carpentry work. The muscle originated from the palmaris longus tendon and ulnar antebrachial fascia at the lower half of the forearm as a single belly, then diverged medially from palmaris longus tendon and bifurcated. Both portions of the split muscle extended into the distal ulnar tunnel or Guyon's canal. One segment joined with the abductor digiti minimi muscle and the other with the flexor retinaculum. MR was able to clearly delineate this hypertrophied, symptomatic muscle anomaly. It may be helpful when mass effect is suspected in either tunnel, or in patients with atypical work-related carpal tunnel syndrome with evidence of significant ulnar neuropathy for evaluation of underlying anomalous musculature. Normal MR images of the wrist are included for comparison and the literature is reviewed.

Current status of percutaneous vascular procedures.

The current nonsurgical therapeutic options for patients with peripheral vascular disease are rapidly expanding. No longer is conservative management the only alternative for patients with significantly symptomatic but noncritical limb ischemia. Certainly for vascular disease above the inguinal ligament interventional procedures especially with adjunctive stent placement have excellent success and long term patency. Femoropopliteal vascular disease of relatively limited nature also is well-treated with interventional procedures. Infrapopliteal vascular disease treated with a surgical venous bypass appears to have superior results than intervention. However, for poor surgical risk patients or in patients without the necessary venous conduit, limb salvage is still good with a percutaneous approach. Renal artery stenosis appears now to be well treated with interventional techniques. Early data with up to one year follow-up shows that even ostial stenoses respond well when vascular stents are utilized. Extending the life of failing hemodialysis grafts is another area where interventional techniques are of benefit. In the future, more extensive vascular disease and other vascular disease entities such as cerebrovascular disease and abdominal aortic aneurysm may be successfully treated by a percutaneous approach.

Case report 802: Ewing's tumor of the proximal phalanx of the third finger with radiographic progression documented over a 6-year-period.

In summary, a case of Ewing's tumor of the proximal phalanx of the long finger of the right hand was presented. This case is unusual because of its location as well as the unusually long clinical course before the correct diagnosis was made. The major point to be stressed is that Ewing's tumor may initially present with a "benign" appearance mimicking a bone cyst [17] or angioma [12]. Timely follow-up of so-called benign lesions, particularly when recurrent swelling occurs, would help in avoiding prolonged delays in diagnosis.

MR demonstration of a persistent median artery in carpal tunnel syndrome.

The median artery of the forearm appears early in embryological development and normally involutes before birth. In rare cases, it persists into adult life. Although usually asymptomatic, it can be a cause for carpal tunnel syndrome (CTS). This report describes the MR appearance of a persistent median artery in a patient with CTS. The symptoms were relieved after resection of the aberrant vessel.

MRI of suprascapular neuropathy in a weight lifter.

Suprascapular neuropathy results from abnormal compression of the suprascapular nerve, typically at the suprascapular or spinoglenoid notch. This may be produced by either mass effect such as ganglion cyst or by certain repetitive shoulder motions producing wide scapular excursion (e.g., hyperabduction), which causes traction upon the nerve. Certain sports activities such as weight lifting predispose to this type of neuropathy. The clinical presentation is frequently not specific and the patient may be sent for MR evaluation to rule out rotator cuff tear or other more common shoulder abnormalities. This entity should be suspected if MR images demonstrate selective atrophy of the spinatus muscles with a structurally intact rotator cuff.

Chronic bursitis presenting as a mass in the pes anserine bursa: MR diagnosis.

A case of chronic, nonspecific synovial inflammation presenting as a mass in the pes anserine bursa is demonstrated by MRI. The lesion was well demarcated and surrounded by a low intensity rim. On spin echo images it was homogeneous and of intermediate signal intensity, whereas on T2-weighted images it showed scattered areas of high signal producing a heterogeneous pattern. It is contrasted with a typical example of acute pes anserine bursitis, presenting as simple fluid within the bursa. The differential considerations vary accordingly between the acute and chronic forms of pes anserine bursitis, with the latter requiring differentiation from other forms of synovitis, synovial hemangioma, and synovial sarcoma. The MR features of these entities are reviewed as an aid in differential diagnosis.

Post-traumatic synovitis presenting as a mass in the suprapatellar bursa of the knee. MRI appearance.

A lobulated mass in the suprapatellar bursa of the knee is presented with MRI findings simulating the features of focal pigmented villonodular synovitis (PVS). Microscopic examination demonstrated a nonspecific, inflammatory mass of hypertrophied synovium. The MRI features of various forms of synovitis are reviewed from recent literature and differential considerations of a suprapatellar, intrabursal mass are discussed.

MR imaging of the quadriceps tendon: normal layered configuration and its importance in cases of tendon rupture.

OBJECTIVE: The quadriceps tendon is a multilayered structure with separate layers arising from different muscle groups. We examined this layered configuration on MR images to determine if it is relevant in the evaluation of the traumatized quadriceps tendon. MATERIALS AND METHODS: Sagittal and axial T1-weighted MR images of 52 knees with normal tendons were reviewed to determine the number and the muscle origins of these layers. Five knees with traumatized quadriceps tendons were imaged with T1 and T2 weighting to determine the relationship between the layered configuration and the injury. RESULTS: All the normal quadriceps tendons had a laminated appearance with either four (6%), three (56%), or two (30%) layers. In 8%, the laminations were barely perceptible. The site of origin of each layer was consistent, and each favored a given muscle. The superficial layer originated from the posterior fascia of the rectus femoris muscle, and the deep layer originated from the anterior fascia of the midline vastus intermedius muscle. The middle layer(s) arose from the deep fascia separating the vastus medialis and the vastus lateralis muscles from the vastus intermedius muscle. When only two layers were present, the middle layer merged with the superficial and deep layers. In the injured tendon, complete rupture produced transection of all the layers. Incomplete ruptures were seen as focal discontinuities of individual layers; other layers remained intact. CONCLUSION: The existence of a layered configuration of the quadriceps tendon is significant in the MR examination of partial ruptures. It can help not only in detecting and localizing injuries but also in determining appropriate treatment based on the number or thickness of injured layers.

MRI versus CT and US in the evaluation of a patient presenting with superior vena cava syndrome. Case report.

Three cross-sectional imaging modalities are compared in the evaluation of a patient with Superior Vena Cava Syndrome. The apparent and potential advantages of magnetic resonance imaging (MRI) over computer tomography (CT) and ultrasound (US) are discussed.

The ulnar tunnel at the wrist (Guyon's canal): normal MR anatomy and variants.

The ulnar tunnel (Guyon's canal) is a fibroosseous tunnel along the anteromedial portion of the wrist that contains the ulnar nerve and artery. As with the adjacent carpal tunnel, its main clinical significance is that it may cause nerve compression. The purpose of this study was to determine whether the anatomy of this area could be depicted in sufficient detail by MR imaging for MR to be useful in the evaluation of patients with ulnar neuropathy. MR studies of 36 wrists of volunteers were reviewed with attention to the size and shape of the canal, its anatomic boundaries, the presence of anomalous muscles, the size and bifurcation of the ulnar nerve, and the presence of a fibrous or muscular arch overlying the deep motor branch of the ulnar nerve. T1-weighted transverse MR images of 3-mm-thick sections were obtained by using either an extremity coil or dedicated wrist coil. Excellent anatomic delineation was achieved. The boundaries and shape of the canal varied from proximal to distal, but no statistical differences were present in the mean cross-sectional area of the canal. Anomalous muscles were present in the canal in nine (25%) of 36 wrists; six (67%) of the nine were bilateral. The ulnar nerve had a mean diameter of 3 mm and bifurcated an average distance of 12 mm from the proximal margin of the pisiform bone. Delineation of the fibromuscular arch at the origin of the flexor digiti minimi brevis muscle was limited by imager resolution, but 50% were judged to be fibrous and 50% to be muscular. Our results show that MR images depict the ulnar tunnel in excellent detail. Since those structures associated with ulnar neuropathy are clearly delineated by MR, the procedure should be useful in the evaluation of patients suspected of having ulnar nerve compression within the tunnel.

Marginal fractures of the lateral malleolus in association with other fractures in the ankle region.

Eight cases of avulsion-type fracture of the distal fibula associated with fracture of the calcaneus, talus, or ankle region were identified. This avulsion fracture can be identified on routine radiographs as well as on CT scans of the ankle and is pathognomonic of rupture of the superior peroneal retinaculum with or without peroneal tendon displacement. Recognition of this avulsion fracture, with subsequent proper management of the underlying peroneal tendon pathology by immobilization or surgery, may prevent future tendon dysfunction. It may also alter the treatment of other associated injuries.

Internal fixation of radial neck fracture in a fracture dislocation of the elbow. A case report.

A 27-year-old manual laborer presented with dislocation of the right elbow, complete separation of the radial head at the neck level, and avulsion of the coronoid process. Closed reduction of the elbow resulted in ulnohumeral instability. As an alternative to silastic implant, the radial head was reduced, internally fixed, and used as a spacer to restore elbow stability. The radial head fracture healed with no sequelae. At two years follow-up examination, the patient had a stable elbow with nearly full range of motion.

Titanium hip implants for improved magnetic resonance and computed tomography examinations.

The value of magnetic resonance imaging (MRI) for assessment of the hip has been demonstrated, particularly in cases of avascular necrosis. Magnetic resonance imaging can be used to provide anatomic evaluation of the femoral head, acetabulum, hip joint, joint fluid, and the surrounding structures. MR examinations of two patients with hip fractures fixed with stainless steel hip implants were compared with nine patients with hip fractures fixed with titanium hip implants, one of which showed avascular necrosis of the femoral head. The titanium implants resulted in less MRI artifacts, allowing for improved depiction of the femoral head and surrounding soft tissue. For this reason titanium fixation devices are recommended as a substitute for stainless steel in the hip joint region in a patient who may need future MR examination.

The radiologic diagnosis of autopsy-proven ventilator-associated pneumonia.

An abnormal chest roentgenogram is essential for the diagnosis of ventilator-associated pneumonia. The diagnostic accuracy of various roentgenographic signs of pneumonia has not been assessed previously in the portable anteroposterior roentgenograms obtained in ventilated patients. Seven roentgenographic signs (air bronchograms, alveolar infiltrates, silhouette sign, cavities, fissure abutment, atelectasis, and asymmetric infiltrates superimposed on diffuse bilateral infiltrates) were evaluated for their accuracy in predicting pneumonia alone, in combination with other signs, or in combination with clinical parameters. The last roentgenogram prior to autopsy of 69 ventilated patients was interpreted by three reviewers and the above signs were correlated with autopsy evidence of pneumonia. Pneumonia was present in 24 (35 percent) of the 69 autopsies. No roentgenographic sign had a diagnostic efficiency of greater than 68 percent. By stepwise logistic regression, the presence of air bronchograms was the only roentgenographic sign that correlated with pneumonia in the total group, correctly predicting 64 percent of pneumonias. In patients without adult respiratory distress syndrome (ARDS), the presence of air bronchograms or alveolar infiltrates correlated with pneumonia, while in patients with ARDS, no roentgenographic sign and only the clinical parameter of purulent sputum correlated with pneumonia. Only a minority (7/22) of worsening alveolar infiltrates in all groups were due to pneumonia and were often confused with ARDS. Alveolar hemorrhage occurred with a surprising frequency (38 percent of autopsies), including 13/45 (29 percent) patients without pneumonia. Alveolar hemorrhage was associated with 29 percent of multiple air bronchograms and 30 percent of bilateral alveolar infiltrates in patients without pneumonia. We conclude that in intubated patients with diffuse bilateral roentgenographic infiltrates, no roentgenographic sign correlates well with pneumonia. No clinical parameter added to the accuracy of either an alveolar infiltrate or an air bronchogram in patients without diffuse infiltrates. Pulmonary hemorrhage and/or infarction are frequent autopsy findings in intubated patients and may be confused radiologically with pneumonia.

Percutaneous decompression for femoral neuropathy secondary to heparin-induced retroperitoneal hematoma: case report and review of the literature.

Retroperitoneal hematoma resulting in femoral nerve injury is a serious potential complication of systemic heparin anticoagulation. Review of the literature reveals lack of agreement with respect to conservative versus surgical management. The authors report the first case in which return of function was established by percutaneous decompression of a retroperitoneal hematoma in a patient who was not a candidate for immediate surgery. The favorable result suggests that percutaneous drainage may represent a reasonable alternative or first step in surgical treatment of this compression.