Mechanism-based pattern approach to classification of complex injuries of the knee depicted at MR imaging.

Complex knee injuries are common, often resulting from multiple forces: varus, valgus, hyperextension, hyperflexion, internal rotation, external rotation, anterior or posterior translation, and axial load. Certain combinations of forces are known to cause specific injury patterns. After a review of the literature, the authors developed a mechanism-based classification system based on patterns of bone marrow edema and ligament injury for complex knee injuries depicted at magnetic resonance imaging. The classification system takes into account knee position and forces and recognition of patterns of bone injury and complementary soft-tissue injury. Ten mechanism-based injury patterns were recognized: (a) pure hyperextension, (b) hyperextension with varus, (c) hyperextension with valgus, (d) pure valgus, (e) pure varus, (f) flexion with valgus and external rotation, (g) flexion with varus and internal rotation, (h) flexion with posterior tibial translation, (i) patellar dislocation (flexion, valgus, and internal rotation of femur on fixed tibia), and (j) direct trauma. Recognition of these patterns may help assess the full extent of knee injury, particularly at the posterolateral and posteromedial corners of the knee.

Evaluation of bone contusions with fat-saturated fast spin-echo proton-density magnetic resonance imaging.

OBJECTIVE: To evaluate the efficacy of fast spin-echo proton-density magnetic resonance imaging (MRI) with fat saturation sequences in the evaluation of bone contusions at the knee. METHODS: Analysis of 46 consecutive knee MRI examinations performed on patients referred from a sports medicine clinic after knee trauma. All examinations included coronal fast spin-echo proton-density fat saturation, fast spin-echo proton-density and fast spin-echo T2-weighted sequences. All 3 coronal sequences were blindly reviewed independently of each other by 3 experienced musculoskeletal radiologists to identify and grade bone contusions. RESULTS: Thirty-five bone contusions were identified in 24 patients. All bone contusions were identified on fast spin-echo proton-density fat saturation sequences, which was significantly greater than the percentage identified on either fast spin-echo T2-weighted sequences (21/35, 60%, p < 0.001) or fast spin-echo proton-density sequences (10/35, 29%, p < 0.001). Fourteen (40%) of the contusions were identified only on the fast spin-echo proton-density fat saturation sequences. The average grade of contusion for all 35 examinations was also significantly higher on the fast spin-echo proton-density fat saturation sequences than on the fast spin-echo proton-density and fast spin-echo T2-weighted sequences (p < 0.05). CONCLUSION: Fast spin-echo proton-density fat saturation sequences are more sensitive in the detection of bone contusions than fast spin-echo proton-density and fast spin-echo T2-weighted sequences. Assessment of other structures in the knee with fast spin-echo proton-density fat saturation MRI provides good spatial resolution and adequate T2-weighted information. It may have advantages over the more heavily T2-weighted fast spin-echo T2 fat saturation and inversion recovery sequences.

Frequency analysis of echo texture in tendon.

A texture discriminant based on spatial frequencies is proposed for characterizing B-scans of Achilles' tendon. The anisotropic echo texture of normal tendon has an ellipsoidal spatial spectrum that can be quantified by the ratio of the major-to-minor axis and by the direction of the major axis. Applying a moving window to the B-scan, a corresponding tissue elliptical axis ratio (TEAR) image is derived that segments out tendon. The algorithm was applied to B-scan images taken from 13 volunteers, 6 of whom had tendon abnormalities: tendon rupture (n = 3) or cholesterol deposits (xanthomas) in patients with heterozygous familial hypercholesterolemia (n = 3). The average TEAR value was 1.75 +/- 0.17 for normal tendon, 1.04 +/- 0.06 for torn tendon, and 1.31 +/- 0.16 for tendons with xanthomas. The dispersion of the directionality vectors was used to further differentiate tendons with xanthomas from normal tendons. This technique appears to be useful for characterizing both diffuse and focal tendon abnormalities.

Semi-quantitative ventilation/perfusion scintigraphy and single-photon emission tomography for evaluation of lung volume reduction surgery candidates: description and prediction of clinical outcome.

Ventilation/perfusion scans with single-photon emission tomography (SPET) were reviewed to determine their usefulness in the evaluation of lung volume reduction surgery (LVRS) candidates, and as a predictor of outcome after surgery. Fifty consecutive planar ventilation (99mTc-DTPA aerosol) and perfusion (99mTc-MAA) scans with perfusion SPET of patients evaluated for LVRS were retrospectively reviewed. Technical quality and the severity and extent of radiotracer defects in the upper and lower halves of the lungs were scored from visual inspection of planar scans and SPET data separately. An emphysema index (EI) (extent x severity) for the upper and lower halves of the lung, and an EI ratio for upper to lower lung were calculated for both planar and SPET scans. The ratios were compared with post-LVRS outcomes, 3, 6 and 12 months after surgery. All perfusion and SPET images were technically adequate. Forty-six percent of ventilation scans were not technically adequate due to central airway tracer deposition. Severity, extent, EI scores and EI ratios between perfusion and SPET were in good agreement (r = 0.52-0.68). The mean perfusion EI ratio was significantly different between the 30 patients undergoing biapical LVRS and the 17 patients excluded from LVRS (3.3+/-1.8 versus 1.2+/-0.7; P<0.0001), in keeping with the anatomic distribution of emphysema by which patients were selected for surgery by computed tomography (CT). The perfusion EI ratio correlated moderately with the change in FEV1 at 3 months (r = 0.37, P = 0.04), 6 months (r = 0.36, P = 0.05), and 12 months (r = 0.42, P = 0.03), and the transition dyspnea index at 6 months (r = 0.48, P = 0.014) after LVRS. It is concluded that patients selected to undergo LVRS have more severe and extensive apical perfusion deficits than patients not selected for LVRS, based on CT determination. SPET after aerosol V/Q imaging does not add significantly to planar perfusion scans. Aerosol DTPA ventilation scans are not consistently useful. Perfusion lung scanning may be useful in selecting patients with successful outcomes after LVRS.

Treatment of micronodular lung metastases of papillary thyroid cancer: are the tumors too small for effective irradiation from radioiodine?

Our purpose was to determine if micronodular lung metastases from papillary thyroid cancer had diameters that were less than 1 mm and therefore of a size for which irradiation by radioiodine (131I) is inefficient. In five patients, lung metastases seen on computed tomography (CT) were enumerated and sized in the entire right lung and right upper lung giving volumes of measurable, ie, more than 1 mm diameter, tumors. Concentrations of diagnostic 131I were quantified scintigraphically in the same regions. Fractions of administered 131I per milliliter of tumor and the absorbed radiation from the subsequent treatments were calculated to see if the 131I levels in lungs were greater than expected for the visible tumor volumes. Two other patients manifesting similar findings had lung biopsies that were reviewed for size of metastases. The calculated fractions of administered activity per milliliter of tumor and the absorbed radiations from the treatments with 131I were exceptionally high. Biopsies revealed numerous tumors below the resolution of CT. We conclude that the fractions of administered activity and absorbed radiations of 131I in tumors were high because the measured tumor volumes underestimated the total tumor volumes. Many lung metastases were less than 1 mm in diameter.

Correlation of Continuous EEG Monitoring with [O-l5]H2O Positron Emission Tomography Determination of Cerebral Blood Flow during Balloon Test Occlusion of the Internal Carotid Artery. Experience in 34 cases.

SUMMARY: The purpose of this paper was to evaluate the utility of continuous electroencephalography (EEG) during balloon test occlusion (BTO) of the internal carotid artery (ICA). Continuous EEG monitoring and [O-15] H2O PET cerebral blood flow (CBF) studies were completed in 34 patients undergoing BTO of the ICA. CBF determinations were obtained as a baseline without carotid occlusion, and following balloon occlusion, with continuous EEG monitoring. Patients were divided into three groups based on clinical and CBF response to BTO. Group I had no clinical signs or symptoms and had a CBF decrease less than 10 ml/l00 g/min ipsilateral to the occlusion. Group II had no symptoms but CBF fell to 35 to 25 ml/l00 g/min on the occluded side. Group III were clinically unable to tolerate occlusion or CBF fell to less than 25 ml/l00 g/min on the occluded side. The results of continuous 21 channel EEG monitoring were assessed at the time of the examination and retrospectively reviewed for changes in the EEG pattern indicative of ischaemia. On the basis of PET CBF, eighteen patients were classified as Group I, four as Group II, and twelve as Group III. EEG evidence of ischaemia was seen in three patients, all members of Group III. Of the three patients, only one patient had clinical signs or symptoms of ischaemia. All four patients in Group II had PET quantitated CBF levels indicating carotid sacrifice should be done with caution or following a presacrifice by-pass procedure, and nine patients in Group III with PET quantitated CBFs below eligibility for carotid sacrifice, were not identified by EEG monitoring. Even when CBF falls below 25 ml/100 g/minute continuous EEG monitoring is insensitive to reduction in perfusion. Reliance upon EEG for detection of cerebral hypoperfusion in interventionl neuroradiological procedures will significantly underestimate ischaemic risk.

[O-15]H2O Positron Emission Tomography Determination of Cerebral Blood Flow Reserve after Intravenous Acetazolamide during Balloon Test Occlusion of the Internal Carotid Artery.

SUMMARY: The purpose of this paper was to evaluate the effects of acetazolamide on cerebral blood flow (CBF) measured by [O-15]H2O positron emission tomography (PET) during balloon test occlusion (BTO) of the internal carotid artery (ICA). [O-15]H2O PET cerebral blood flow studies were completed in 20 patients undergoing BTO CBF determinations were obtained without carotid occlusion as a baseline, following balloon occlusion, and as a third scan with balloon occlusion after an intravenous acetazolamide bolus. The balloon was left deflated between scans, and was only inflated immediately before and during the 90 second period of time needed for CBF determination. Significance was determined at the P < 0.05 level. Two of twenty studies were technical failures. Prior to acetazolamide there was a significant decrease in CBF (P < 0.0007) ipsilateral to the occlusion. After acetazolamide administration there was no statistically significant change in flow on the occluded side (P < 0.3047); however, there was a significant increase in cerebral blood flow (P < 0.0002) on the non-occluded side. In this patient population, there was no acetazolamide-induced CBF decompensation (steal) phenomenon or haemodynamically significant risk in CBF ipsilateral to the occlusion.

Methods of cardiopulmonary support: a review for radiologists.

Physicians are generally aware of the use of bypass pumps during open heart surgery and of the intraaortic balloon pump in treatment of cardiogenic shock. In selected research centers, other advanced methods of cardiopulmonary support are being introduced. Some devices such as the total artificial heart fail clinical trials and disappear from use. Others, like some of the partial artificial hearts, improve outcomes and gain wider clinical use. Some devices temporarily support the circulation in patients recovering from acute circulatory collapse, whereas others provide longer-term circulatory support for patients awaiting transplantation. Permanently implanted devices provide circulatory assistance in cases of chronic, debilitating heart failure. Technology to support lung function in the setting of acute respiratory failure, allowing healing to take place, is also under study. Radiologists should be familiar with the operating principles and radiographic appearances of these emerging techniques to maintain their role as consultants to cardiopulmonary specialists.

Thin-section CT obtained at 10-mm increments versus limited three-level thin-section CT for idiopathic pulmonary fibrosis: correlation with pathologic scoring.

OBJECTIVE: The purpose of our study was to determine if three-level thin-section CT depicts idiopathic pulmonary fibrosis (IPF) pathology as accurately as CT obtained at 10-mm increments throughout the entire lungs. SUBJECTS AND METHODS: Thin-section (1.0- to 1.5-mm) images at 10-mm increments were obtained and scored prospectively in 25 consecutive patients with newly diagnosed IPF who were participating in a Special Center of Research grant for interstitial lung disease. Each patient's lobe was scored by four thoracic radiologists on a scale of 0-5 for both ground-glass attenuation and fibrosis. The radiologists used three images (limited CT) and also used the entire data set (complete CT). CT scores were compared with pathology scores from 67 open and thoracoscopic biopsies. Limited and complete scores were compared with each other (Pearson correlation coefficient). Interobserver variation in the CT scoring system was assessed using kappa values. RESULTS: CT fibrosis scores strongly correlated with pathology fibrosis scores for complete (r = .53, p = .0001) and limited (r = .50, p = .0001) CT. CT ground-glass scores correlated with the histologic inflammatory scores for each lobe on complete (r = .27, p = .03) and limited (r = .26, p = .03) CT. The desquamative subcomponent of the pathology inflammatory score had the highest correlation with the CT ground-glass scores (complete: r = .29, p = .01; limited: r = .33, p = .007). Good interobserver agreement existed for both the alveolar and fibrosis components of the CT scoring system (kappa values ranging from .51 to .83) for each lobe of the lung on limited and complete CT. CONCLUSION: Limited thin-section CT reveals the pathologic changes associated with IPF as well as CT obtained at 10-mm increments. An added advantage of limited thin-section CT is that it exposes patients to less radiation.

Specificity of radioiodinated MIBG for neural crest tumors in childhood.

UNLABELLED: The high sensitivity of metaiodobenzylguanidine (MIBG) scintigraphy for sympathomedullary tumors such as neuroblastoma and pheochromocytoma is well documented. The specificity of MIBG scintigraphy for these tumors is also high but has been incompletely characterized for other neural crest tumors and non-neural crest tumors of childhood. METHODS: The medical records and MIBG scans of all children who had undergone MIBG scintigraphy for known or suspected neuroblastoma or pheochromocytoma were retrospectively reviewed at five major referral centers. Those patients found to have pathologies other than neuroblastoma or pheochromocytoma form the basis of this study. RESULTS: One hundred children with a total of 110 lesions met the inclusion criteria. All had negative MIBG scans except 1 of 2 children with infantile myofibromatosis, 1 of 2 with neuroendocrine carcinomas, 1 of 2 with pancreaticoblastomas and 1 of 10 with primitive neuroectodermal tumors. CONCLUSION: MIBG scintigraphy is highly specific for neuroblastoma and pheochromocytoma. Only 4% (4/100) of nonsympathomedullary tumors (non-pheochromocytoma and non-neuroblastoma) in childhood showed MIBG uptake, of which only 2% (2/100) were of non-neural crest origin.

CT appearance of lipomatous hypertrophy of the interatrial septum.

OBJECTIVE: We undertook this study to determine the CT findings of lipomatous hypertrophy of the interatrial septum, an asymptomatic and underrecognized benign proliferation of fat within the atrial septum. MATERIALS AND METHODS: We retrospectively identified 12 cases of lipomatous hypertrophy of the interatrial septum by searching the radiology records at our institution from 1991 to 1995. We reviewed the CT scans of these patients to determine the distribution and morphology of fat within the interatrial septum. RESULTS: In all patients with lipomatous hypertrophy, a mass of fat attenuation extended from the coronary sinus to just above the level of the aortic root with relative sparing of the fossa ovalis, which resulted in a dumbbell configuration. Average dimensions were 7 cm for craniocaudal extent (range, 6-9 cm), 4.5 cm along the interatrial septum (range, 3.6-6.2 cm), and 2.7 cm perpendicular to the septum (range, 1.5-4.8 cm). Increased epicardial fat was seen on CT scans in 10 patients (83%). CT revealed mediastinal lipomatosis in six patients (50%). No patients had undergone corticosteroid treatment or total parenteral nutrition. No electrocardiographic or functional cardiac abnormalities were seen. CONCLUSION: On standard, high-resolution, and enhanced CT images, lipomatous hypertrophy of the interatrial septum is shown as a nonenhancing smoothly marginated homogeneous dumbbell-shaped mass of fat attenuation confined to the interatrial septum. These characteristic morphologic features allow confident diagnosis and help differentiate this benign condition from other cardiac masses.

131-I treatment of micronodular pulmonary metastases from papillary thyroid carcinoma.

BACKGROUND: Pulmonary metastases from papillary thyroid carcinoma shorten the survival of the hosts. Treatments with 131-I have been reported to induce disappearance of these tumors in a large proportion of afflicted patients. In this study, consecutive patients with diffuse micronodular lung metastases from papillary thyroid carcinoma were examined to determine if disappearance of tumor occurred, and how much disappeared, after substantial amounts of 131-I were administered. METHODS: Of 232 patients treated with 131-I for thyroid carcinoma between 1985 and 1994, 12 patients between the ages of 5 and 45 years exhibited evidence of micronodular metastases to the lungs that concentrated 131-I. Each patient had undergone total or nearly total thyroidectomy and cervical lymph node dissection. All neoplasms were well differentiated papillary carcinoma, but one also had focal, poorly differentiated insular components. Follicle formation by tumors varied from less than 10% to 100% of the histologic sections. Effects of treatment were measured by three indices: chest X-ray and/or CT images, scintigraphic images, and serum thyroglobulin levels. Individual activities of 131-I ranged from 2.2 gigabequerel (GBq) (initial activity in the 5-year-old patient) to 13 GBq, and were greater than 7.4 GBq in 6 patients. Only one treatment was given to three patients, two were given to seven, and more than two were given to two. The duration of follow-up was at least one year. RESULTS: In two patients, the only evidence of lung metastases was on scintigraphic images made a few days after treatment. Another patient had a normal X-ray but showed diffuse uptake of 131-I in the lungs on a diagnostic scintiscan. Of the nine patients with abnormal X-ray and CT images, seven showed improvement, but tumors disappeared in only two. In the ten patients with abnormalities on the diagnostic scintiscans, five eventually manifested no abnormality. At the outset, thyroglobulin levels exceeded 10 ng/mL in each patient; 3 individuals exhibited a decline in level by 25% or more, and a value of less than 6 ng/mL, uncomplicated by thyroglobulin antibodies, was seen in two patients. Only two patients attained normality in all three indices. Hematologic toxicity was modest and reversible. CONCLUSIONS: Despite a number of previous reports that pulmonary metastases from thyroid carcinoma disappear in approximately half of patients treated with 131-I, evidence of tumor reduction was found in most, but a complete remission occurred in only 2 of 12 patients. Nevertheless, 131-I therapy may be useful to decrease the tumor burden in many such patients.

Pneumomediastinum: elucidation of the anatomic pathway by liquid ventilation.

Partial liquid ventilation is a new technique to improve oxygenation in patients with severe acute respiratory distress syndrome. In a patient with status asthmaticus and tension pneumothorax treated with subsequent liquid ventilation, radiopaque perfluorocarbon was identified along brochiovascular structures, in the mediastinum, and in the retroperitoneum. Perfluorocarbon outlined on CT and chest radiography the anatomic pathway by which spontaneous pneumomediastinum develops following alveolar rupture, as described earlier by histopathologic study in animals. This represents the radiopaque equivalent of radiolucent pneumomediastinum. Perfluorocarbon remained in the pulmonary interstitium on radiography 30 days after beginning liquid ventilation, without sequelae.

Extracorporeal membrane oxygenation in adults: radiographic findings and correlation of lung opacity with patient mortality.

PURPOSE: To describe the radiographic appearance of extracorporeal membrane oxygenation (ECMO) in adults and to correlate lung opacity with physiologic parameters and mortality. MATERIALS AND METHODS: Chest radiographs of 50 adults treated with ECMO were reviewed; pre-ECMO radiographs were available in 35 patients. Lung opacity was assigned a score of 0-4. Complications of ECMO seen at chest radiography were recorded. RESULTS: The lung opacity scores of the first post-ECMO radiographs were higher than those of the pre-ECMO radiographs in 17 of 35 patients (P = .0005). Maximum opacity score was significantly lower for patients who survived compared with those who died (P = .001). Twelve of 14 patients (86%) with a maximum opacity score of 4 died, compared with eight of 29 patients (28%) with a maximum score of 3. Sixteen of 26 patients (61%) with evidence of baro-trauma died, compared with six of 24 patients (25%) without pneumothorax (P = .02). Four patients developed hemothorax. CONCLUSION: Lung opacity increases immediately after initiation of ECMO. Increased opacity corresponds to decreased pulmonary function, and severe opacity correlates strongly with mortality.

Pulmonary zygomycosis: CT appearance.

OBJECTIVE: We describe the CT appearance of pulmonary zygomycosis (mucormycosis), an opportunistic infection typically occurring in immunocompromised patients. MATERIALS AND METHODS: Eight patients with pulmonary zygomycosis imaged with CT were reviewed, seven at initial diagnosis and one with a subsequent complication. The appearance, number, and location of pulmonary lesions and the presence of pleural effusions and extrapulmonary involvement were assessed. Rim enhancement, air bronchograms, the halo sign, air crescent sign, cavitation, and central low attenuation suggesting necrosis were recorded. RESULTS: There were 14 nodules and 5 areas of mass-like or wedge-shaped consolidation. Pleural effusion was present in five patients, halo sign in three, central low attenuation in two, and cavitation in one. In the affected lobe 13 of 14 nodules and all consolidations were posterior. Of 19 lesions 16 (84%) were confined to the upper lobes, with 3 in the superior segment of a lower lobe. Endobronchial disease with lobar collapse was the only manifestation in one patient. Major complications were direct spinal invasion in one patient and multiple pulmonary artery pseudoaneurysms in another patient. CONCLUSION: In the appropriate clinical circumstance, nodules or mass-like or wedge-shaped consolidation, especially posteriorly in the upper lobes of the lung, should suggest zygomycosis. Endobronchial zygomycosis is less common.

Case report: radiological appearances in peliosis hepatis.

Peliosis hepatis is an unusual disorder characterized by blood filled hepatic spaces. We describe the appearances of this entity on ultrasonography, computed tomography and magnetic resonance imaging. The importance of peliosis hepatis is that it may be an indicator of a treatable underlying condition.