Ferumoxides-enhanced MR imaging is more accurate than unenhanced MR imaging and at least as accurate as CTAP for the detection of hepatic metastases.

Airways remodelling is a feature of longstanding asthma, but may differ in persons with allergic and nonallergic asthma. To assess airways remodelling indirectly, we compared permanent CT-scan abnormalities in 70 subjects with allergic (median age: 30 yr) and 56 with nonallergic asthma (median age: 54.5 yr) who had had asthma of similar duration. None of the subjects were smokers. Asthma severity was assessed by Aas score and FEV1. Permanent high-resolution computed tomographic (HR-CT) scan abnormalities were characterized. In comparison with allergic asthmatic subjects, those with nonallergic asthma had a significantly greater frequency of cylindric (p < 0.0007, Mann-Whitney U test) and varicose (p < 0.004) bronchiectasis, emphysema (p < 0.0003), bronchial recruitment (p < 0.0001), and sequellar linear shadows (p < 0.0001). There was a significant correlation between Aas score and emphysema (p < 0.0001 for nonallergic and p < 0.0005 for allergic asthma; Kendall's test method) or Aas score and sequellar linear shadows (p < 0.007, nonallergic asthma). There was a significant increase in the extent of permanent abnormalities with increasing severity and duration of asthma in both groups. Patients with brittle asthma had few permanent abnormalities. This study confirms that after a similar course of the disease, patients with nonallergic asthma have a more extensive remodelling of the airways than those with allergic asthma.

CT scans have been studied only in asthmatics who were smokers, and no such study has been performed in patients with chronic uncomplicated asthma where a permanent bronchial destruction is likely to occur after a long course of the disease. The object of the study was to characterize CT-scan abnormalities and determine whether bronchial destructive lesions may be observed. Fifty-seven adults with chronic asthma of variable severity and etiology and 10 normal subjects were studied. None of the subjects smoked. Chest radiographs and HR-CT scans were performed in all patients. To discriminate between reversible and irreversible CT-scan abnormalities, two examinations were made in 10 patients with acute asthma both before and 2 wk after parenteral high dose corticosteroid treatment. The chest radiographs showed the expected abnormalities of asthma in 37.8% of the asthmatics. CT scans were abnormal in 71.9% of the asthmatics. Reversible abnormalities included mucoid impactions, acinar pattern, and lobar collapse. Irreversible abnormalities included bronchiectasis, bronchial wall-thickening, sequellar line shadows, and emphysema. Most of these abnormalities are likely to be related to bronchial destruction.

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An ultrasmall superparamagnetic iron oxide (USPIO) preparation was evaluated as a potential intravenous contrast agent for magnetic resonance (MR) imaging of bone marrow. One hour after administration of USPIO (40, 80, and 160 mumols of iron per kilogram body weight) in rats and rabbits, T1 and T2 relaxation times were, respectively, approximately 30%, 50%, and 65% lower than precontrast relaxation times. Maximum decrease in relaxation times of marrow occurred within 1-24 hours after intravenous administration; thereafter, relaxation times slowly returned to normal within 7 days. In vivo MR imaging of rabbits and rats confirmed that USPIO decreases signal intensity of red and yellow marrow. The decrease was most marked with gradient echo pulse sequences. An animal model of intramedullary tumor demonstrated the potential of USPIO to enable differentiation between tumor and normal red marrow. USPIO-enhanced MR imaging improves detection of smaller tumors and allows differentiation of tumor deposits from islands of hyperplastic or normal red marrow.