Principles and applications of echo-planar imaging: a review for the general radiologist.

Echo-planar imaging is a very fast magnetic resonance (MR) imaging technique capable of acquiring an entire MR image in only a fraction of a second. In single-shot echo-planar imaging, all the spatial-encoding data of an image can be obtained after a single radio-frequency excitation. Multishot echo-planar imaging results in high-quality images comparable to conventional MR images. However, echo-planar imaging offers major advantages over conventional MR imaging, including reduced imaging time, decreased motion artifact, and the ability to image rapid physiologic processes of the human body. The use of echo-planar imaging has already resulted in significant advances in clinical diagnosis and scientific investigation, such as in evaluation of stroke and functional imaging of the human brain, respectively. The clinical indications for echo-planar imaging are expanding rapidly, and it can now be applied to many parts of the body, including the brain, abdomen, and heart. Today, with the availability of echo-planar imaging-capable MR imagers at many sites, the general radiologist can benefit from echo-planar imaging and its clinical applications.

Magnetic resonance imaging in acute pyelonephritis.

The diagnosis of acute pyelonephritis in children remains a clinical challenge. We assessed the feasibility of magnetic resonance imaging (MRI) detection of pyelonephritis in four pediatric patients and compared the results with renal cortical scintigraphy. MRI revealed areas of high signal intensity in the kidney that coincided with photon-deficient regions in the radionuclide scans in two children with acute pyelonephritis. These findings confirm work in experimental animals and indicate that MRI can accurately detect acute pyelonephritis in children.

Deep juvenile xanthogranuloma: an unusual presentation.

Juvenile xanthogranuloma (JXG) is a disorder of histiocytes usually associated with cutaneous lesions. It may present a diagnostic dilemma in the absence of cutaneous lesions and when deeply located. Differentiation of JXG from other childhood histiocytosis syndromes, especially Langerhans' cell histiocytosis (LCH), is important. We describe an unusual case of deep JXG in a 27-month-old girl with multiple omental and peritoneal nodules presenting with ascites. Although a diagnosis of LCH was suspected clinically, the absence of Birbeck granules and S-100 protein and T6 antigen negativity, together with CD68 and factor XIIIa positivity, led us to a diagnosis of JXG. Physicians should be aware of the widening spectrum of manifestations of juvenile xanthogranuloma.

Extraperitoneal abdominopelvic inflammatory pseudotumor: report of four cases.

We describe four cases of inflammatory pseudotumor seen at our institution in the past 4 years. Four children were each found to have a large extraperitoneal mass on imaging studies, three of which were in the pelvis. Malignant sarcomatous tumors were suspected. Surgical biopsy of each mass, however, revealed inflammatory pseudotumor.

Pyloric volume: an important factor in the surgeon's ability to palpate the pyloric "olive" in hypertrophic pyloric stenosis.

OBJECTIVE: The objective of this study was to determine whether the size of the pyloric mass is one of the factors in the surgeon's ability to palpate the pyloric "olive". MATERIALS AND METHODS: The ultrasonographic images and medical records of 60 infants with surgically confirmed hypertrophic pyloric stenosis (HPS) were reviewed. The pyloric diameter (PD) and pyloric length (PL) were measured and the pyloric volume (PV) was calculated using the equation PV = 1/4pi x (PD)2 x PL. Based on the pediatric surgeon's physical examination the infants were divided into two groups: those with and those without palpable pyloric masses. RESULTS: Infants with a palpable pyloric mass had an average pyloric volume of 3.33 +/- 1.76 mm3, which was statistically larger than those whose hypertrophied pylorus could not be palpated (average volume 2.59 +/- 2.07 mm3, P < 0.01). There was no statistically significant age difference between the two groups. CONCLUSION: Clinical skill of the examiner and other clinical aspects (patient cooperation, etc.) determine palpability of the pylorus in HPS. The size of the hypertrophied pylorus is also an important factor affecting the clinician's ability to palpate the pyloric mass.

Spiral computed tomographic scanning of the chest with three dimensional imaging in the diagnosis and management of paediatric intrathoracic airway obstruction.

BACKGROUND: The usefulness of spiral computed tomographic (CT) scans of the chest with three dimensional imaging (3D-CT) of intrathoracic structures in the diagnosis and management of paediatric intrathoracic airway obstruction was assessed. METHODS: A retrospective review was made of five consecutive cases (age range six months to four years) admitted to the paediatric intensive care unit and paediatric radiology division of a tertiary care children's hospital with severe respiratory decompensation suspected of being caused by intrathoracic large airway obstruction. Under adequate sedation, the patients underwent high speed spiral CT scanning of the thorax. Non-ionic contrast solution was injected in two patients to demonstrate the anatomical relationship between the airway and the intrathoracic large vessels. Using computer software, three-dimensional images of intrathoracic structures were then reconstructed by the radiologist. RESULTS: In all five patients the imaging results were useful in directing the physician to the correct diagnosis and appropriate management. In one patient, who had undergone repair of tetralogy of Fallot with absent pulmonary valve, the 3D-CT image showed bilateral disruptions in the integrity of the tracheobronchial tree due to compression by a dilated pulmonary artery. This patient underwent pulmonary artery aneurysmorrhaphy and required continued home mechanical ventilation via tracheostomy. In three other patients with symptoms of lower airway obstruction the 3D-CT images showed significant stenosis in segments of the tracheobronchial tree in two of them, and subsequent bronchoscopy established a diagnosis of segmental bronchomalacia. These two patients required mechanical ventilation and distending pressure to relieve their bronchospasm. In another patient who had undergone surgical repair of intrathoracic tracheal stenosis three years prior to admission the 3D-CT scan ruled out restenosis as the reason for her acute respiratory decompensation. CONCLUSIONS: 3D-CT scanning is a useful additional diagnostic tool for intrathoracic airway obstruction in paediatric patients.

Simultaneous occurrence of osteosarcoma and osteochondroma following treatment of neuroblastoma with chemotherapy, radiotherapy, and bone marrow transplantation.

Radiation-induced bone changes and second malignancies, as well as benign tumors, following bone marrow transplantation are being reported with increasing frequency. An osteosarcoma of the fourth right rib and an osteochondroma of the left scapula developed in a long-term survivor of abdominal neuroblastoma treated with chemotherapy, local radiation, and bone marrow transplantation. All these treatment modalities are known to induce neoplasia.

Papillary-cystic neoplasm of the pancreas.

Papillary-cystic neoplasm of the pancreas is a rare, nonfunctioning low-grade malignant tumor seen in young patients, most often female. Ultrasound and CT show a circumscribed, solid nonhomogeneous mass with cystic areas, with peripheral but not central enhancement and occasional calcification. Prognosis after excision is usually excellent. We describe a case of the papillary-cystic neoplasm of the pancreas in a 13-year-old girl to illustrate the radiological findings.