Biomedical subjects

L H Lowe

Publications and source records attributed to L H Lowe.

23 records · Page 2Linked to original sources

PubMedDate not supplied

Mass effect in the renal sinus: an anatomic classification.

Before the advent of modern imaging techniques, pathologic processes in the renal sinus were diagnostic enigmas. Many of the conditions create nonspecific deformities of the contrast-filled collecting system. In the past, the discovery of these abnormalities often led to unnecessary exploration. Modern imaging techniques usually allow a specific diagnosis to be made, but because a number of the pathologic conditions affecting the renal sinus have similar appearances on a single type of imaging study, complete delineation may require correlation of a number of diagnostic techniques. An understanding of the normal sinus anatomy allows classification of pathologic processes that occur in this region and ensures an orderly imaging investigation. The anatomic classification is based on the structure from which the mass arises. The source of the mass may be any structure within the renal sinus (intrinsic), the enveloping renal parenchymal (adjacent), or a source outside the kidney itself with subsequent sinus involvement (extrinsic). This classification will be used to review a number of pathologic processes that occur in the renal sinus and pertinent imaging features.

Diagnosis, Differential↗

PubMedDate not supplied

Sensorineural hearing loss in children.

A variety of pathologic conditions cause sensorineural hearing loss in infants and children. Modern imaging techniques such as high-resolution computed tomography (CT) and magnetic resonance (MR) imaging have made it possible to identify a specific cause of pediatric hearing loss in many cases. A classification system has been developed that groups these abnormalities into three anatomic locations along the cochlear nerve: the labyrinth, the internal auditory canal, and the brain stem and cerebrum. Unenhanced high-resolution CT remains the imaging modality of choice in evaluating most cases of pediatric sensorineural hearing loss. In general, CT is the preferred modality in cases of trauma and nonacute congenital otic capsular dysplasias, whereas contrast material-enhanced MR imaging is preferred in cases of inflammatory and neoplastic disorders. Documented acute hearing loss in an older child or adolescent should also be studied with contrast-enhanced MR imaging. Reliable radiologic evaluation requires accurate clinical information as well as knowledge of normal inner ear anatomy and abnormal imaging findings.

Brain↗

PubMedDate not supplied

Midface anomalies in children.

A variety of congenital midface anomalies occur in children. High-resolution computed tomography (CT) and magnetic resonance (MR) imaging have proved helpful in determining the nature and extent of dysplasia, thereby facilitating treatment planning. A classification system has been developed that groups these anomalies into four categories based on embryogenesis and anatomic location. These categories comprise anomalies that are related to the nasal cavity, nasofrontal region, nasolacrimal apparatus, and craniofacial syndromes. CT is the imaging modality of choice in children with possible choanal atresia, pyriform aperture stenosis, or anomalies of the nasolacrimal duct (eg, nasolacrimal duct stenosis, dacryocystoceles). MR imaging is the modality of choice in patients with congenital midface masses (eg, dermoid and epidermoid cysts, nasal gliomas, encephaloceles) and craniofacial syndromes (eg, Apert syndrome, Crouzon syndrome, Treacher Collins syndrome). In many cases, however, both CT and MR imaging are required to adequately evaluate midface anomalies. Familiarity with the characteristic imaging features of these anomalies along with knowledge of midface embryogenesis and normal developmental anatomy is essential to prevent misinterpretation of anatomic variations that may simulate disease.

Child↗

PubMedDate not supplied

Pediatric renal masses: Wilms tumor and beyond.

A variety of pediatric renal masses may be differentiated from Wilms tumor on the basis of their clinical and imaging features. Wilms tumor is distinguished by vascular invasion and displacement of structures and is bilateral in approximately 10% of cases. Nephroblastomatosis occurs most often in neonates and is characterized by multiple bilateral subcapsular masses, often associated with Wilms tumors. Renal cell carcinoma is unusual in children except in association with von Hippel-Lindau syndrome and typically occurs in the 2nd decade. Mesoblastic nephroma is the primary consideration in a neonate with a solid renal mass. Multilocular cystic renal tumor is suggested by a large mass with multiple cysts and little solid tissue. Clear cell sarcoma is distinguished by frequent skeletal metastases, and rhabdoid tumor is distinguished by its association with brain neoplasms. Angiomyolipoma frequently contains fat and is associated with tuberous sclerosis. Renal medullary carcinoma occurs in patients with sickle cell trait or hemoglobin SC disease and manifests as an infiltrative mass with metastases. Ossifying renal tumor of infancy is differentiated from mesoblastic nephroma by the presence of ossified elements. Metanephric adenoma lacks specific features but is always well defined. Renal lymphoma is characterized by multiple homogeneous masses, often with associated adenopathy.

Child↗

PubMedDate not supplied

Swelling at the angle of the mandible: imaging of the pediatric parotid gland and periparotid region.

The pediatric parotid gland and periparotid region are subject to a variety of lesions and are most often evaluated with ultrasonography (US), contrast material-enhanced computed tomography (CT), and magnetic resonance (MR) imaging. US may be used to assess the size of the parotid gland, distinguish diffuse from focal disease, assess vascularity and adjacent vascular structures, distinguish cystic from solid lesions, and guide fine-needle aspiration. However, further evaluation with CT or MR imaging may be needed to better define the nature and extent of disease. CT is the imaging modality of choice for most pediatric parotid disease (including acute inflammation, abscess, calculi, and major salivary duct obstruction) and most solid masses and may obviate sedation. However, a mass associated with facial nerve symptoms should be evaluated with MR imaging because it is the only modality that can consistently demonstrate the facial nerve. Findings at US, CT, and MR imaging allow localization of parotid lesions and may suggest a specific cause. Clinical information, familiarity with normal parotid anatomy at various stages of its development, and knowledge of the imaging characteristics of parotid and periparotid lesions are essential for appropriate radiologic evaluation. This information can be used to guide therapy and plan a surgical approach.

Child↗