Magnetic resonance imaging in cystic fibrosis.

A clinical dilemma in patients with cystic fibrosis is the determination of the nature of linear areas of decreased aeration in the lungs. It is difficult using chest roentgenograms or even computed tomography to differentiate atelectasis, mucoid impacted bronchi, or peribronchial inflammatory disease from normal pulmonary vascularity. Magnetic resonance imaging is a noninvasive sensitive means that provides the distinction. Pulmonary vessels are easily identified, because with the spin-echo sequence that we use, the rapidly flowing blood within the vessels has no signal intensity. In contradistinction, mucoid-impacted bronchi appear as high-intensity linear branching structures. Peribronchial inflammatory disease appears as curvilinear areas of high intensity, representing inflammatory edema, around central lucencies representing bronchi.

Orbital tumors in children. Characterization by computed tomography.

CT characteristics of orbital masses in 39 children were reviewed. Histological types and their relative frequencies differed considerably from reported adult cases. Analysis of seven separate CT characteristics for each type of mass indicated certain trends which may aid in the differential diagnosis.

Magnetic resonance imaging of the thorax in childhood. Work in progress.

Magnetic resonance (MR) imaging was performed in 10 children with intrathoracic disease. Entities imaged included mediastinal lymphoma and neuroblastoma, pulmonary metastases from hepatoblastoma and osteogenic sarcoma, hemorrhagic pleural effusion, and nonmalignant disease such as abscess, cystic fibrosis, and bronchogenic cyst. MR imaging was particularly valuable in delineating mediastinal and parenchymal masses from adjacent vascular structures without the need for contrast material enhancement. However, MR was insensitive to lesion calcification. Since pulmonary vessels give very low signal, differentiation of high-intensity pulmonary nodules from vessels is readily apparent. For similar reasons, MR was excellent in distinguishing endobronchial mucus plugs from peripheral pulmonary vessels.

Nuclear magnetic resonance imaging of the brain in children.

Nuclear magnetic resonance imaging of the hydrogen nucleus provides a unique noninvasive display of proton dynamics in biologic tissues and fluids as well as internal anatomy in a sectional imaging format. No ionizing radiation is utilized. Our experience with NMR imaging of the brain in 14 pediatric patients is presented and compared with computed tomography. The major advantages of NMR over CT include its greater sensitivity to blood flow, edema, hemorrhage, and myelinization and its lack of beam-hardening artifacts. In addition, the potential for tissue characterization exists by determination of T1 and T2 relaxation times and of mobile proton density. Disadvantages of NMR over CT include its failure to demonstrate calcification and bone detail and longer data acquisition times.

Juvenile rheumatoid arthritis of the knee: MR evaluation with Gd-DOTA.

Synovial hypertrophy, effusion, and articular cartilage status were evaluated with gadolinium tetraazacyclododecanetetraacetic acid (DOTA)-enhanced magnetic resonance (MR) imaging in 24 knees in 24 pediatric patients (17 female, seven male; mean age, 10 years; range, 3-18 years) with juvenile rheumatoid arthritis (JRA). T1-weighted spin-echo sequences were performed with a 0.5-T unit before and immediately after injection of Gd-DOTA (0.1 mmol/kg). Substantial enhancement of synovial proliferation was seen in 23 of 24 knees, allowing precise assessment of pannus extension (n = 23), joint effusion (n = 21), cartilage loss (n = 21), and meniscal hypotrophy (n = 23). On T1-weighted images without contrast enhancement, cartilage thickness, loculation of joint effusion, and pannus extension were underestimated. Thus, Gd-DOTA-enhanced MR imaging is mandatory in the assessment of knee involvement in children with JRA and may prove to be useful in the evaluation of response to therapy.

Work in progress: nuclear magnetic resonance study of a paramagnetic nitroxide contrast agent for enhancement of renal structures in experimental animals.

A piperidinyl nitroxide stable free radical derivative, TES, was tested as an NMR contrast enhancer of renal structures in normal animals and animals with experimentally induced unilateral renal ischemia, renal vascular congestion, and hydronephrosis. Physiologic measurements indicated that TES is rapidly excreted in the urine with a clearance rate equal to the glomerular filtration rate. Because the compound is strongly paramagnetic, it increases the observable NMR intensity within the kidneys and urine in relatively low doses (0.04 to 0.9 g/kg). TES-enhanced spin echo renal images clearly demonstrated the presence of disease and functional abnormalities in diseased kidneys. These abnormalities were either not evident or only indirectly suggested on nonenhanced NMR images.