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Biomedical subjects

V B Ho

Publications and source records attributed to V B Ho.

At least 37 records · Page 2Linked to original sources
PubMed1997

Preoperative gadolinium-enhanced magnetic resonance pulmonary venography in an adolescent with atrial septal defect.

The conventional preoperative evaluation of congenital heart disease in the adult using only echocardiography and cardiac catheterization is frequently limited. We report a case in which newer magnetic resonance imaging with gadolinium angiographic techniques proved helpful by conclusively documenting normal pulmonary venous return in a patient with secundum [corrected] atrial septal defect. This evaluation obviated the need for referral to a more specialized tertiary-care center for congenital heart disease and dramatized the value of an interdisciplinary approach to the adult patient with newly diagnosed congenital heart disease.

Adolescent↗
PubMed1996

Contributions of newer MR imaging strategies for congenital heart disease.

Magnetic resonance (MR) imaging is a valuable noninvasive adjunct in the evaluation of congenital heart disease (CHD). With its multiplanar image acquisition, good spatial resolution, and large-field-of-view image display, MR imaging can allow appreciation of vascular connections not readily apparent at echocardiography or angiography. Evaluation of CHD with MR imaging has two components: definition of cardiovascular anatomy and characterization of blood flow. However, the variety of MR imaging options is large and often confusing. Besides spin-echo and gradient-echo imaging, MR imaging techniques for evaluation of CHD include MR angiography, cine MR imaging, and flow quantification. An understanding of the potential MR imaging options enables formulation and more efficient application of MR imaging strategies. When performed well, MR imaging greatly enhances surgical planning and can even obviate cardiac catheterization. MR imaging is also an excellent modality for serial evaluation of surgical results and complications in cases of CHD.

Blood Flow Velocity↗
PubMed1995

Juvenile Huntington disease: CT and MR features.

PURPOSE: To describe the clinical and radiologic manifestations of juvenile Huntington disease and to determine whether adult imaging criteria for Huntington disease are helpful for pediatric patients. METHODS: Six patients (3 to 18 years of age; mean age, 9.8 +/- 5.6 years; 3 female, 3 male) with juvenile Huntington disease were studied with CT (n = 6) and/or MR (n = 3). CT and MR studies were evaluated for frontal horn distance/intercaudate distance and bicaudate ratios, which were compared with those of 24 age-matched healthy children and 12 age-matched patients with Leigh (n = 9) or Wilson (n = 3) disease. RESULTS: Atrophy of the caudate nuclei was identified in all Huntington patients. The frontal horn distance/intercaudate distance (1.64 +/- 0.39) and bicaudate (0.205 +/- 0.060) ratios of the patients with juvenile Huntington disease were found to be significantly different from those of healthy children and that of those patients with Leigh/Wilson disease. The 3 patients with Huntington disease who underwent MR evaluation were noted to have increased proton density- and T2-weighted signal in the caudate nuclei and putamina. CONCLUSION: As in adult patients, the use of frontal horn distance/intercaudate distance and bicaudate ratios are helpful for the diagnosis of Huntington disease in pediatric patients. On MR, increased proton density- and T2-weighted signal in the atrophic caudate nuclei and putamina are additional features of juvenile Huntington disease.

Adolescent↗
PubMed1993

Mitochondrial encephalomyopathy, lactic acidosis, stroke-like episodes (MELAS): clinical, radiological, pathological, and genetic observations.

We reviewed 10 patients (5 males, 5 females) with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes. The age of symptom onset ranged from 3 months to 12 years. All had lactic acidosis, multiple stroke-like events with secondary neurological deficits, radiological changes of progressive brain infarction, and muscle biopsy showing ragged-red fibers. In patients with earlier onset of symptoms (< 2 yr), involvement tended to be more diffuse, with failure to thrive and early onset of delayed development. Patients whose symptoms appeared later tended to have focal neurological deficits with migraine-like headache, and a rate of cognitive regression reflecting the rapidity of disease progression. Radiological changes included multiple areas of infarction with initial predilection for parietal occipital areas, progressing to generalized atrophy. Pathological findings in muscle biopsies included type 1 fiber predominance, ragged-red fibers, increased intermyofibrillar lipid deposition, and abnormal mitochondria. Four patients showed mitochondrial DNA tRNA mutation at position 3,243. No difference was noted in clinical, radiological, or pathological findings in patients with and without this mutation, suggesting that multiple sites of point mutation may give rise to mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes.

Base Sequence↗
PubMed1993

Bilateral basal ganglia lesions: pediatric differential considerations.

Computed tomography (CT) and magnetic resonance (MR) imaging have dramatically improved the ability to visualize the deep gray structures of the basal ganglia (primarily, the caudate nucleus, putamen, and globus pallidus). Any process that alters cerebral metabolism can lead to basal ganglia damage. This article presents the spectrum of disease that may be seen with bilateral basal ganglia abnormalities in the pediatric population. A simplified approach to the differential diagnosis of these entities is based on acute versus chronic conditions and radiologic manifestations. Acute processes include hypoxia, hypoglycemia, carbon monoxide poisoning, hemolytic-uremic syndrome, osmotic myelinolysis, and encephalitis. Chronic conditions include inherited ("inborn errors of metabolism," Huntington disease, and dysmyelinating diseases) or acquired (sequelae of acute disorders) conditions that represent abnormal biochemical or structural processes within the basal ganglia. Elimination of acute causes gives little hope for improvement. Recognition of chronic disorders is important for counseling purposes, since most of these conditions have specific patterns of inheritance.

Acute Disease↗
PubMed1993

Extraosseous Tc-99m MDP uptake: a pathophysiologic approach.

Scintigraphy with technetium-99m methylene diphosphonate (MDP) delineates a wide spectrum of nonosseous disorders. Neoplastic, hormonal, inflammatory, ischemic, traumatic, excretory, and artifactual entities demonstrate abnormal soft-tissue uptake of Tc-99m MDP. Mechanisms leading to increased extraosseous Tc-99m MDP uptake include extracellular fluid expansion, enhanced regional vascularity and permeability, and elevated tissue calcium concentration. The composition of the calcium deposition and the presence of other metallic ions (eg, iron and magnesium) are important. Soft-tissue Tc-99m MDP uptake is seen in benign (tumoral calcinosis, myositis ossificans) and malignant (sarcomas, adenocarcinomas, metastases) neoplastic entities. Hormonal disturbances in calcium metabolism, especially in hyperparathyroidism, can lead to metastatic calcification, visualized with Tc-99m MDP scintigraphy. Tissue damage from inflammation, infection, or physical trauma results in localized hyperemia, edema, or calcium (and hemosiderin) deposition based on their pathophysiologic characteristics. Urinary tract obstruction, anomalies, or dysfunction are demonstrated by Tc-99m MDP imaging. Common artifacts are related to faulty radiopharmaceutical preparation, Tc-99m MDP administration, and imaging technique. Recognition of these modes of extraskeletal Tc-99m MDP uptake can enhance the diagnostic value of bone scintigraphy.

Adult↗
PubMedDate not supplied

Mycotic aneurysm of the aorta: MRI and MRA features.

Mycotic aneurysms of the abdominal aorta are potentially fatal but uncommon. We report the MRI and MRA features of an abdominal aortic mycotic aneurysm in a patient who presented with nonspecific low back pain. By delineating the saccular nature of the aneurysm and identifying the coexistence of vertebral enhancement, MRI was crucial for the final diagnosis. A potential pitfall of contrast-enhanced MRA is also demonstrated.

Aged↗
PubMedDate not supplied

Dorsal defect of the patella: MR features.

Dorsal defect of the patella (DDP) is a benign lesion with characteristic radiologic features. We describe the MR appearance of a typical DDP and a healed DDP as seen in two patients. The classic CT appearance is also described.

Adult↗
PubMedDate not supplied

Primary cardiac lymphoma: CT and MR findings.

Primary cardiac lymphomas, defined as those involving only the heart and pericardium, are extremely rare tumors. These tumors are commonly fatal and until recently were rarely diagnosed antemortem. We describe the CT and MR findings in a case of primary lymphoma of the heart currently responding to chemotherapy.

Heart Neoplasms↗
PubMedDate not supplied

Thoracic MR aortography: imaging techniques and strategies.

Three-dimensional (3D) gadolinium-enhanced magnetic resonance (MR) angiography is a promising technique for thoracic aortography that complements electrocardiographically gated T1-weighted spin-echo imaging and cine MR imaging. Axial and left anterior oblique T1-weighted spin-echo images are well suited to measurement of aortic dimensions and evaluation of aortic aneurysms. Sagittal and coronal spin-echo images are helpful in evaluation of vascular rings and aortic dissection. Cine gradient-echo and cine phase-contrast imaging allow dynamic evaluation of aortic and valvular flow. Cine phase-contrast imaging also enables noninvasive quantification of blood flow. Capable of being performed during a single breath hold, 3D gadolinium-enhanced MR angiography provides high-resolution 3D data that can be readily used for projection angiography and multiplanar reformation. This technique enables further demonstration of subtle pathologic conditions. Three-dimensional gadolinium-enhanced MR angiography allows more comprehensive and efficient evaluation of the thoracic aorta.

Aged↗
PubMedDate not supplied

Chemical shift: the artifact and clinical tool revisited.

The chemical shift phenomenon refers to the signal intensity alterations seen in magnetic resonance (MR) imaging that result from the inherent differences in the resonant frequencies of precessing protons. Chemical shift was first recognized as a misregistration artifact of image data. More recently, however, chemical shift has been recognized as a useful diagnostic tool. By exploiting inherent differences in resonant frequencies of lipid and water, fatty elements within tissue can be confirmed with dedicated chemical shift MR pulse sequences. Alternatively, the recognition of chemical shift on images obtained with standard MR pulse sequences may corroborate the diagnosis of lesions with substantial fatty elements. Chemical shift can aid in the diagnosis of lipid-containing lesions of the brain (lipoma, dermoid, and teratoma) or the body (adrenal adenoma, focal fat within the liver, and angiomyolipoma). In addition, chemical shift can be implemented to accentuate visceral margins (e.g., kidney and liver).

Artifacts↗