David A. Cory

Imaging the diaphragm and its disorders

Although a radiologic evaluation of the diaphragm is important in many clinical situations, visualization of the diaphragm is difficult because of its thinness, its domed contour, and its contiguity with abdominal soft tissues. Each clinical situation involving the diaphragm presents its own imaging difficulties, and each radiographic technique has advantages and disadvantages. No one modality is best for all situations. Often, several imaging modalities must be used to resolve the clinical question. The particular difficulties in diaphragmatic imaging are (1) distinguishing eventration from paralysis or hernia, (2) distinguishing lipoma from herniated omental fat, and (3) distinguishing unilateral paralysis from weakness and bilateral paralysis from respiratory fatigue. By selecting and applying the appropriate radiographic techniques, the radiologist can serve an essential role in assessing the disorders of the diaphragm.

Failure of percutaneous drainage in children with traumatic pancreatic pseudocysts

Recent reports have documented the successful use of percutaneous drainage (PD) in the management of traumatic pancreatic pseudocysts in children. This study presents four cases of pancreatic pseudocyst in which percutaneous catheter drainage was performed. In one instance, no operative therapy was required. However, in the other three cases PD failed to resolve the problem and distal pancreatectomy with splenic salvage was performed when contrast studies (endoscopic retrograde cholangiopancreatography or catheter injection) demonstrated disruption of the main pancreatic duct. This report suggests that children with pancreatic pseudocysts unresponsive to PD require prompt investigation of ductal anatomy to rule out transection or other major injury.

Digital imaging of the newborn chest

The study reports initial experience on utilising an area plate digital imaging system to obtain portable radiographic images on newborn infants. Initial results suggest that the system is a practical alternative to conventional portable radiography with potential advantages of decreasing the number of retake films and also of decreasing radiation dose.

Phosphor plate computed radiography : response to variation in mAs at fixed kVp in an animal model. Potential role in neonatal imaging

Computed digital radiography offers a number of potential advantages over conventional film-screen imaging. To determine the applicability of these to portable neonatal examinations we performed a controlled prospective study comparing conventional 200 speed film-screen with a computed radiography unit in an animal model. Images acceptable for diagnostic purposes were obtained on the digital system over an exposure range many orders of magnitude greater than was possible on the film-screen system. Digital imaging offers potential for elimination of repeat examinations due to suboptimal exposure factors, and for reduction in radiation dose to the patient. We believe that computed digital radiography should be particularly suited to portable neonatal imaging.

Evaluation of pulmonary parenchymal disease by magnetic resonance imaging

Thirty-eight patients with a wide variety of different disorders of the lung have been imaged using magnetic resonance. The disorders studied include congenital abnormalities, acute and chronic inflammation, vascular disorders, primary and secondary tumours of the lung, haematomas and infarcts. Magnetic resonance imaging identified all lesions seen on chest radiographs, but it is not quite as sensitive as computed tomography is for detection of very small abnormalities. Magnetic resonance may provide information to aid in differentiation of a wide variety of disorders causing diffuse pulmonary abnormality and might also prove helpful in differentiating acute inflammation from pulmonary collapse or fibrosis. In some disorders, such as lobar emphysema, cystic adenomatoid malformation and sequestration, the findings on the magnetic resonance scan alone will permit a correct diagnosis to be made in many cases. It is believed that magnetic resonance imaging has more potential for pulmonary imaging than has previously been recognised.

Magnetic resonance imaging of systemic venous anomalies

Seven cases of anomalous development of the systemic great veins were found in the first 18 months of adult body imaging with a 0.15 T resistive magnetic resonance unit. Comparison was made with CT. In most cases, CT and MRI were equivalent in demonstrating the abnormality. In one case, MRI was superior to a drip-infusion CT. MRI was less successful when the low signal abnormal vein was adjacent to normal structures of low signal. Awareness of the MRI appearance of venous anomalies will aid their recognition as incidental findings.

Uptake of technetium 99m MDP by hepatoblastoma

Focal uptake of 99mTc-MDP was seen in a case of hepatoblastoma. The focal uptake corresponded to an area of calcification on CT, which was shown histologically to consist of osteoid with mineralization. The mechanism of uptake by the tumor in this case is likely to be the same as for skeletal uptake.

Comparison of computerized digital and film-screen radiography: Response to variation in imaging kVp

A controlled prospective study, in an animal model chosen to simulate protable neonatal radiography, was performed to compare the response of the Philips Computed Radiography (CR) system and conventional 200 speed film-screen (FS) to variation in imaging kVp. Acceptable images were obtained on the CR system over a very wide kVp range. In contrast the FS system produced acceptable images over a narrow kVp range. This ability suggests that the CR system should eliminate the need for repeat examinations in cases where a suboptimal kVp setting would have resulted in an unacceptable FS image. CR technology should therefore be ideally suited to portable radiography especially in situations where selection of correct exposure factors is difficult as in the neonatal nursery.

Magnetic resonance imaging of extremity masses.

Twenty-seven adults with extremity masses were examined by magnetic resonance imaging (MRI). In 26/27 cases, computed tomography (CT) scans were available for comparison. Imaging with multiple pulse sequences is necessary to optimize diagnosis by MRI. Advantages of MRI include direct sagittal and coronal imaging, demonstration of vessels without contrast and superior soft tissue contrast. CT better demonstrates cortical destruction and small calcifications, which may be important in some cases. For noncalcified masses without bone involvement, MRI is equivalent or superior to CT. In those cases with calcification or bone involvement, MRI plays a role complementary to CT.