Injuries about the knee and tibial/fibular shafts.

Injuries to the knee and tibial/fibular shafts are extremely common, with knee injuries alone accounting for over 1.3 million emergency department visits yearly in the United States. Many of these injuries will present with straightforward radiographic findings, but others will have a subtle or complex appearance. This article reviews injuries of the knee and proximal tibial/fibular shaft with emphasis on normal anatomic features that, when disrupted, indicate the presence of subtle but important bone or soft tissue trauma. Although the emphasis is on plain radiography, magnetic resonance (MR) and computed tomographic (CT) findings are discussed where appropriate.

An in vivo magnetic resonance imaging study of changes in the volume (and fluid content) of the lumbar intervertebral discs during a simulated diurnal load cycle.

STUDY DESIGN: Magnetic resonance imaging was used to measure the changes in volume of the lumbar intervertebral disc in vivo during a load cycle. OBJECTIVES: To measure changes in volume of the lumbar intervertebral disc during a load cycle and relate these changes to changes in fluid content. SUMMARY OF BACKGROUND DATA: There have been very few experiments conducted to measure the volume and fluid changes in intervertebral discs in vivo. METHODS: Five healthy subjects were recruited (aged 27, 29, 31, 34, and 52 years) in a study using magnetic resonance imaging to measure the changes in volume of the lumbar intervertebral disc in vivo, during a load cycle. The experiment was designed to simulate a diurnal load cycle, but over less time. The load cycle consisted of bed rest, followed by walking with a 20-kg backpack for 3 hours, followed by bed rest for 3 hours. Magnetic resonance imaging scans of the lumbar spine were obtained 10 times during this load cycle. The disc volume was calculated by summing the disc area contained in each slice of the scan. The changes in volume of the discs (L2-L3, L3-L4, and L4-L5) recorded at the 10 times were then related to the fluid changes. RESULTS: Load-induced changes in disc volume can be detected and measured using MR imaging. The average volume increase 3 hours after removing a highly compressive load was 5.4%. The water content of the nucleus and anulus in the disc of the young human is said to be approximately 80% and 70%, respectively. If the disc gained 5.4% of its initial total volume, and assuming that the initial fluid content was approximately 75%, then it gained approximately 7% (i.e., 5.4%/75% x 100% approximately 7%) of its fluid. CONCLUSIONS: Load-induced changes in disc volume can be detected and measured using magnetic resonance imaging.

The use of the diagnostic radionuclide ascites scan to facilitate treatment decisions for hepatic hydrothorax.

A 44-year-old man had an intractable right-sided pleural effusion due to cirrhosis, despite the absence of abdominal ascites. Instillation of Tc-99m macroaggregated serum albumin under CT guidance into the peritoneal space demonstrated transdiaphragmatic communication. This finding indicated the necessity for decompressing the portal system to treat the hydrothorax. The diagnostic radionuclide ascites scan may play an important role in the treatment approach to such patients.

Diffuse abdominal uptake of technetium-99m-HDP after colectomy in Gardner's syndrome.

A 37-yr-old man presented with increasing abdominal girth and multiple palpable intra-abdominal masses 3 yr after colectomy for polyposis coli. Whole-body skeletal scintigraphy performed prior to laparotomy demonstrated diffuse abdominal uptake of 99mTc-HDP consistent with mesenteric fibromatosis confirmed at surgery. When diffuse abdominal uptake of skeletal imaging agents occurs in patients with prior colectomy for polyposis coli, mesenteric fibromatosis as a manifestation of Gardner's syndrome should be suspected. This case illustrates another cause of diffuse abdominal uptake of skeletal imaging agents.

Tibial plateau fractures: evaluation with MR imaging.

Thirty patients with 31 tibial plateau fractures, initially diagnosed with standard radiography, were further studied with biplane linear tomography and magnetic resonance (MR) imaging. Each fracture was categorized according to the Schatzker classification. The extent of comminution and articular depression was determined for each modality. MR images were also evaluated for the presence of accompanying meniscal and ligamentous injury. In each case, MR imaging was noted to be as effective as tomography in depicting the amount of articular depression. MR imaging was found to be more effective than tomography in determining the extent of comminution. Beyond demonstrating the fracture, MR imaging was capable of revealing associated ligamentous and meniscal injuries. There was an increased prevalence of accompanying soft-tissue injuries in those fracture types that are associated with more violent forces and as the extent of articular depression increased. MR imaging is a useful and effective means of preoperatively evaluating tibial plateau fractures.

Search for influence of 1.5 Tesla magnetic field on growth of yeast cells.

We have used a clinical magnetic resonance imager to search for the possible effects of a 1.5 T magnetic fields on the growth of the yeast Saccharomyces cerevisiae. Yeast samples were grown in nutrient broth contained in constant-temperature boxes, both in and out of the magnetic field of the imager. Growth was measured by using a hemocytometer and light microscope to calculate cell densities. Over the time span corresponding to approximately seven cell divisions, we find no convincing statistical evidence for an effect of magnetic field on cell density.

Apparent change in cardiac geometry during single-photon emission tomography thallium-201 acquisition: a complex phenomenon.

We investigated the frequency and extent of changes in heart position and geometry independent of body motion during stress single-photon emission tomography (SPET) thallium-201 myocardial perfusion imaging. Following an exercise treadmill test, patients had a 22.1-min SPET acquisition which was followed immediately by a static image acquisition for 1 min with the camera position identical to the first view of the SPET study. Point sources were placed on the body to monitor patient motion. Cardiac motion was assessed by an approach which mimicked a cross-correlation technique applied to cardiac count profiles along the horizontal and vertical directions from the first view of the SPET study and the static image. A large percentage (87.5%) of cases had some degree of horizontal or vertical motion. Pixel shifts in cardiac position of > or = 2 pixels (12 mm) occurred in 60% of patients. In 37% of patients who moved the cardiac motion was consistent with simple translation of the heart and thus amenable to correction using proposed SPET motion-correction programs. The peak heart rate achieved during stress and the ratio of the heart rate immediately before SPET acquisition to the resting heart rate were determined to be independent predictors of patient motion during SPET acquisition. Cardiac motion changes were minimal at (13.3 +/- 2.2) min after cessation of exercise. The implications of these findings for the accuracy of SPET 201Tl require further investigation.

Evaluation of phlegmasia cerulea dolens using radionuclide venography.

Phlegmasia cerulea dolens (PCD) is characterized by the presence of massive venous occlusion of the veins in an extremity, leading to ischemia and sometimes gangrene. We report a case of phlegmasia cerulea dolens that was evaluated by radionuclide venography. We report both this case and information regarding phlegmasia and therapy of PCD to promote awareness of this disorder among radiologists and nuclear medicine physicians who perform radionuclide venograms.

Magnetic resonance imaging of knee menisci. Comparison of spin echo pulse sequences.

Magnetic resonance imaging (MRI) is accurate in evaluating meniscal tears using spin echo pulse sequences. The purpose of this study was to systematically compare T1-weighted pulse sequences to two echo proton density/T2 (2eT2)-weighted sequences. Menisci were separated into four grades based on signal characteristics. In addition, all menisci were graded as positive or negative for tear. Twenty-three patients (46 menisci) were studied with both pulse sequences and the results were compared with arthroscopic findings. Using T1 sequences, 14 of 18 torn menisci and 26 of 28 untorn menisci were identified. Using 2eT2 sequences, 13 of 18 torn menisci and 26 of 28 untorn menisci were correctly identified. There was high correlation between T1 and 2eT2 sequences for torn versus untorn menisci and for grade of injury (P = .99). There is very little difference between T1- and 2eT2-weighted pulse sequences in evaluation of meniscal tears.

A directed approach to MRI of the athletic knee.

Surface coil MRI is now frequently utilized to assess acutely injured knees. In dedicated athletes, unique considerations exist which modify standard diagnosis and therapy. Concrete clinical findings must justify the potential loss of livelihood from even a "negative" arthroscopy. Seventeen injured athletes were evaluated by an orthopedic surgeon experienced in sports injuries and a preliminary localizing diagnosis was rendered, followed by knee MRI. Of 17 patients with significant injuries, MRI agreed with operative findings or clinical follow-up in 15 cases. Knee MRI prompted early intervention in those patients with conflicting subjective and/or objective findings. Furthermore, it helped direct the arthroscopist's surgical approach and encouraged close examination of areas less optimally visualized arthroscopically. MR and arthroscopy were complementary modalities in diagnosing certain ligamentous and cartilaginous lesions. MR effectively evaluated the cruciate ligaments often difficult to visualize by arthroscopy; arthroscopy better assessed articular surfaces. A cooperative effort existed between orthopedic surgeon and radiologist in directing both the MR study and arthroscopy. This was of particular benefit in maximizing scan efficiency in these large individuals who often filled the gantry. The team directed approach between orthopedic surgeon and radiologist affords deliberate and efficient diagnosis and therapy in this select population.

False positive V/Q imaging in pulmonary contusion.

Pulmonary contusion and embolism are frequent complications of trauma. The radionuclide imaging finding of pulmonary embolism, a segmental ventilation/perfusion mismatch, has been documented in the literature to occur in pulmonary contusion, without, however, excluding concurrent pulmonary embolus by arteriography. The authors report a case of ventilation/perfusion mismatch due to pulmonary contusion with normal pulmonary arteriography.

MRI of the athletic knee. Findings in asymptomatic professional basketball and collegiate football players.

For the dedicated athlete in whom minor injuries are frequent and major injuries relatively common, a noninvasive knee assessment could either obviate the need for arthroscopy or focus its direction. The opportunity to study asymptomatic athletes was not feasible before the advent of magnetic resonance imaging (MRI). In this preliminary work, we examined 40 knees in 20 asymptomatic volunteer athletes, including five professional basketball players and 15 collegiate football players. Images were obtained at 0.5 T or 1.5 T. Spin echo sequences were used to obtain 5.0 mm thick coronal and sagittal sections. Fifty percent of asymptomatic athletes (10/20) had significant baseline MRI abnormalities that could have adversely affected scan interpretation in the context of an acute injury. Half of these athletes with MRI abnormalities, or 25% of the total (5/20), had no previous surgery and were unaware of significant injury.

MR imaging diagnosis of rotator cuff tears.

Thirty-one symptomatic patients were studied with MR imaging to evaluate the sensitivity and specificity of shoulder MR in the diagnosis of rotator cuff tears. Correlative studies included arthroscopy in 19 patients and arthrography in 12 patients. Images were obtained on either a 0.5- or 1.5-T Philips superconducting magnet using spin-echo pulse sequences (650-850/30 [TR, TE], 2000/30, 100) with 5-mm slices oriented in an oblique coronal plane perpendicular to the glenohumeral joint. The MR studies were initially interpreted without knowledge of the results of other diagnostic procedures. The MR diagnosis of cuff tear was made when irregularity, discontinuity, and increased signal were identified in the rotator cuff. MR images showed tears in 10 patients (32%) and were negative for tear in 21 patients (68%). MR correlated with arthroscopy and arthrography in 17 of 18 normal patients, in eight of 10 patients with complete tears, and in one of three patients with partial tears. For complete rotator cuff tears, the sensitivity, specificity, and accuracy were 80%, 94%, and 89%, respectively. For all tears (partial and complete), the sensitivity, specificity, and accuracy were 69%, 94%, and 84%, respectively. These data suggest that MR imaging is an accurate procedure for the diagnosis of complete rotator cuff tears. The number of partial tears (three) in this series is too small to evaluate the value of MR imaging in the diagnosis of partial tears.

Splenic infarction at low altitude in a child with hemoglobin S-C disease.

We describe a 15-year-old black boy with hemoglobin S-C disease living in Atlanta (altitude 1,034 ft), with no prior history of aircraft or mountain travel, who developed splenic infarction. The clinical picture was characterized by severe left upper quadrant abdominal pain, fever, splenomegaly, and hematologic and scintigraphic evidence of functional asplenia. The diagnosis was suggested by liver/spleen scintigraphy and further confirmed by ultrasonography and computerized tomography (CT) of the spleen. Treatment consisted of analgesics, intravenous fluids, and short-term antibiotic therapy. The child recovered without sequelae.

Comparison of cardiac function in surgically corrected and congenitally corrected transposition of the great arteries.

The capacity of the anatomic right ventricle to sustain normal function against systemic pressure long after atrial baffle procedures in patients with complete transposition of the great arteries remains unknown. Pulmonary and systemic ventricular function was measured by first-pass radionuclide studies in 11 children 7 +/- 3 years (+/- standard deviation) after baffle procedures. For comparison, similar measurements were made in eight patients with isolated congenitally corrected transposition of the great arteries and in 10 children in a control group. Exercise increased heart rate and cardiac index to similar levels in all three groups. Ventricular volumes were greater than control volumes in both groups with congenital heart disease. Exercise increased pulmonary ventricular ejection fraction in the control and congenitally corrected groups, but not in the surgically corrected group. Systemic ventricular ejection fraction increased during exercise in the control group, but remained unchanged in both transposition groups. These results show that cardiac index during exercise is maintained in patients after baffle procedures for complete transposition of the great arteries. However, pulmonary and systemic ventricular ejection fractions fail to increase with exercise, and ventricular volumes are markedly greater than normal.

Relation of coronary artery stenosis and pressure gradient to exercise-induced ischemia before and after coronary angioplasty.

The purpose of this investigation was to evaluate the relation of coronary artery stenosis and associated pressure gradient to the magnitude of exercise-induced left ventricular dysfunction in patients with single vessel coronary artery disease. The percent stenosis and minimal cross-sectional area were measured before and after percutaneous transluminal coronary angioplasty and compared with radionuclide measurements of left ventricular function before and after angioplasty in 41 patients with proximal left anterior descending coronary artery lesions, providing 82 points of comparison. The gradient could be measured for 75 comparisons. Forty stenoses less than 50% were associated with a mean left ventricular exercise ejection fraction of 0.66 +/- 0.08 (mean +/- SD), 25 stenoses from 50 to 75% with a mean ejection fraction of 0.59 +/- 0.12 and 17 stenoses greater than 75% with a mean ejection fraction of 0.49 +/- 0.08. Thirty-five stenoses with a gradient less than 20 mm Hg were associated with a mean ejection fraction of 0.65 +/- 0.09, 24 with a gradient from 20 to 50 mm Hg with a mean ejection fraction of 0.58 +/- 0.13 and 16 with a gradient greater than 50 mm Hg with a mean ejection fraction of 0.53 +/- 0.10. These data document a relation between the magnitude of coronary artery stenosis and associated gradient to exercise-induced left ventricular dysfunction in homogeneous patient groups. However, discordance of these variables occurs commonly in individual patients.

Ectopic parathyroid gland. Localization with thallium-201 SPECT.

Dual isotope Tl-201/Tc-99m subtraction is a useful technique for localization of abnormal parathyroid glands. A case of tomographic localization of nonsubtracted Tl-201 to a mediastinal parathyroid is reported and the possible benefit of this method discussed.