Biomedical subjects
Publications and source records attributed to S Chuang.
Forty-three infants and children underwent conventional or CT ventriculography after instillation of metrizamide into the ventricular system. The procedure had few complications. Anatomic detail of intraventricular obstruction was good. With CT additional physiologic information can be obtained.
The air gap type of CT scanner with tilting gantry allows the use of head positions other than the standard semi-axial. The modified Water's or clival-perpendicular position is especially useful in the diagnosis of posterior fossa disease. The position offers a view that is approximately coronal to the clivus and tentorium. The clival-perpendicular view easily separates the supra- and infratentorial compartments. It also helps to differentiate extra- and intra-axial lesions and to locate the fourth ventricle, and it gives far better vertical orientation of posterior fossa pathology.
Computed tomographic metrizamide myelography (CTMM) has developed into a highly sophisticated and accurate neuroradiologic technique in the diagnosis of childhood spinal dysrhaptic states. Of the 84 patients studied by this technique, 31 with the dysrhaphic spine also had lesions such as a tethered and low conus, diastematomyelia, or neuroenteric cysts. We believe that the exquisite pathologic anatomy obtained by CTMM obviates all neuroradiologic techniques other than a preliminary anteroposterior and lateral spinal roentgenograph.
A rare case of hypertrophic osteoarthropathy (HO) limited to one lower extremity is described in a male with a history of familial polyposis coli and bilateral aortofemoral grafts. The precise etiology remains unknown. Radiography depicted the HO, but 99m Tc-methylene diphosphonate imaging showed more extensive involvement. An intra-aortic injection of 99m Tc-macroaggregates of albumin portrayed a larger blood flow to the involved limb compared to the contralateral extremity. The major part of this increase was in bone rather than in the adjacent soft tissue.
Computed tomographic metrizamide myelography (CTMM) is an accurate and satisfactory method for examining the spinal cord in infants and children. Twenty-three patients with spinal dysraphism have been studied by CTMM. This method has proven more informative than conventional myelography in the evaluation of the dysraphic state.
Expiratory collapse of the trachea was demonstrated radiographically in three infants with esophageal atresia who developed episodes of severe upper respiratory obstruction in the first few weeks of life. The abnormality is most readily seen fluoroscopically in such patients, though tracheal narrowing may be visible on an expiratory lateral chest radiography. An unusually long tracheostomy tube may be required to bypass the site of obstruction.
The utility of 99mTc-phosphate imaging of fractured bones adjacent to joints soon after injury is examined. Joints usually respond to trauma by a generalized increased regional concentration of the radiopharmaceutical; but with careful attention to technique, a superimposed focal deposition due to the fractured bone can be seen. Fractures which were initially indefinite or which seemed normal at radiography were revealed as early as 7 hours after injury. In our experience, failure to show a focal concentration beyond 3 days excludes a fracture. However, a focal concentration need not necessarily represent a gross fracture; a ligamentous avulsion of a bone chip and/or periosteum could yield the same picture and not be disclosed by radiography. Radionuclide imaging of joint fractures is a useful adjunct to clinical assessment.
The phenomenology of the manic state and its response to lithium drug treatment were intensively studied as part of a larger NIMH Clinical Research Branch Collaborative Program on the Psychobiology of Depression. In view of the weaknesses in current methods for measuring the components of the manic state, a new instrument was developed, the Manic Diagnostic and Severity Scale (MADS). Its sensitivity in diagnosis and in measuring change was compared to other scales already in use. Finally baseline clinical data is presented that suggests that the presence of a "mixed" manic state is a predictor of lack of clinical response to lithium treatment.
The precise etiology of intellectual impairment in Duchenne muscular dystrophy (DMD) is unknown. Histopathologic and computed tomographic studies have revealed structural brain changes; however, to our knowledge, no cranial magnetic resonance imaging (MRI) studies have been performed on DMD patients to further delineate these structural changes. We prospectively studied 4 DMD patients by cranial MRI, DNA deletion analysis, clinical evaluation, and intelligence testing. There was no significant correlation between verbal intelligence scores and MRI findings, DNA deletion, or the clinical severity of the disease. These first MRI studies of DMD did not reveal any significant anatomic brain alteration, other than mild atrophy in 2 patients. We believe these results must be considered when investigating the etiology of intellectual impairment in DMD in future studies with larger patient samples.
Temporomandibular joint (TMJ) disease is uncommon in children but frequently occurs in juvenile rheumatoid arthritis (JRA). Involvement is often asymptomatic; however, it can lead to growth disturbances and facial deformity. Thirty TMJs in 15 children (11 girls and 4 boys aged 3.5-18 years) with JRA were evaluated clinically and by MRI. Plain films were reviewed when available. Magnetic resonance imaging parameters included T1-weighted and in some cases T2-weighted or gradient recall echo sequences. We assessed condylar configuration, glenoid fossa changes, presence of erosions, disk abnormality, range of motion, and presence of joint effusions or pannus. Abnormalities included cortical erosions (n = 19), disk thinning (n = 18), and perforation (n = 2). Reduction of joint movement (n = 20), joint locking (n = 3), and pannus/effusions (n = 5) were also found. Magnetic resonance imaging is a useful technique for the detection of TMJ involvement in JRA. Early detection and therapeutic intervention may lessen or prevent subsequent deformities.
This paper presents a theoretic study of pharmacokinetic and cell kinetic models for cancer chemotherapeutic systems. The mathematic analysis is based on a modified procedure deduced from DeVita's scheme of the relationship between the cellular kinetics of normal and tumor tissues and the pharmacokinetics of antitumor agents for designing an optimal dose and schedule for cancer treatment. In this scheme pharmacokinetic models and cell-drug interactions at the tumor site are incorporated into the cell cycle kinetic models to form the cancer chemotherapeutic model systems. Three cell cycle kinetic models are presented under alternative hypotheses concerning the mechanism of the resting cells, while each tumor mass is comprised of cells in proliferating (consisting of the four cycle phases G1, S, G2, and M), resting (Go), and non dividing (D, dead) states. An algorithm and a computer program for simulating the tumor populations during scheduled treatments have been prepared. By a suitable selection of expressions for cell-drug interactions, the program is able to simulate tumor behavior during scheduled treatments with different classes of anticancer agent such as cell cycle phase-specific, cell cycle-specific, or cell cycle-specific, or cell cycle-nonspecific drugs. A preliminary study of the L1210-ara-C therapeutic system is included to demonstrate the computer simulation procedures.
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Imaging studies from 13 patients with caudal regression were reviewed retrospectively to assess the spectrum and findings of this anomaly. Seven patients were evaluated with MR and six with myelography (supplemented with CT in three). The level of regression varied from T9 to the coccyx. Although osseous abnormalities were more readily identified and characterized by CT, MR effectively depicted the level of vertebral regression, presence of central spinal stenosis, and vertebral dysraphic anomalies. MR demonstrated a characteristic wedge-shaped (longer dorsally) cord terminus in seven of the patients. When this characteristic cord terminus is seen, imaging of the lower lumbar and sacral regions should be performed to verify the diagnosis of caudal regression. Tethered spinal cords have been described in patients with caudal regression and were seen in two of our patients. We present the first cases of individuals who have survived with absence of vertebrae above the T10 level and an unusual case of caudal regression with absent lumbar vertebrae and preserved lower sacral and coccygeal vertebrae. The syndrome of caudal regression encompasses a wide spectrum of pathology that is analyzed well by modern imaging techniques.
Radiographic findings are reviewed in 31 children with primitive neural ectodermal tumors seen at the Hospital for Sick Children from 1962 through 1983. Seventeen children were initially evaluated with computed tomography (CT). Ten of these had both CT studies and angiography. The tumors were large, irregular, typically iso- to hyperdense, and showed dense, heterogeneous contrast enhancement. Cysts were present in 65% and calcifications in 71% of cases. The angiographic findings were nonspecific, ranging from avascular to markedly vascular. Although these tumors were usually found in the cerebral hemisphere, particularly the frontal lobes, two cases are included of tumors arising elsewhere: one in the pineal and one in the suprasellar region. Epidemiologic data are reviewed.
It is proposed that the vein of Galen aneurysm represents a venous ectasia secondary to an increased flow (usually caused by a deep-seated arteriovenous shunt draining either directly into the vein of Galen aneurysm or into a tributary of the vein of Galen) associated with obstruction of a dural sinus distal to the aneurysm. The closer the venous obstruction is to the vein of Galen, the better the chances are of developing obstructive (noncommunicating) hydrocephalus and the more likely it is that the venous drainage from the rest of the brain will be unaffected. The farther the venous obstruction is from the vein of Galen aneurysm, the better the chances are of developing a communicating type of hydrocephalus. The development of cardiac failure is related to the magnitude of the arteriovenous shunt. Brain damage, seizures, and hemorrhage may be related to the retrograde venous engorgement, causing impaired drainage of the healthy brain. Careful attention should be paid to the venous drainage characteristics of the lesion because the types of dural venous obstructions and anomalies vary from case to case. The term "vein of Galen aneurysm" should be abandoned in favor of the term "vein of Galen ectasia."
Four children are reported in whom marked contrast enhancement of the spinal cord and roots was demonstrated by computed tomography months to years after relatively low dose therapeutic irradiation of paraspinal tumors, the radiation field including the cord. This phenomenon, previously unreported, probably represents subclinical radiation injury. None of the children had any neurologic abnormalities.
Preoperative diagnosis of intracranial cysts has been simplified and made more rapid and accurate with computed tomography (CT). By means of conventional CT and CT metrizamide ventriculography, the position and communication of intracranial cysts with the ventricular system and subarachnoid space or cisterns can be demonstrated. Suprasellar arachnoid cysts can produce significant neurologic and endocrinologic abnormalities due to their position. They are a surgically curable cause of hydrocephalus. Preoperative differentiation from aqueduct stenosis or other causes of a large third ventricle is important. The usefulness of coronal CT and CT metrizamide ventriculography in the investigation of these lesions is illustrated in six patients.
Fourteen cases of inadvertent iatrogenic embolization of cerebral vessels occurring in a consecutive series of 3,731 angiographies in infants and children were studies. The incidence of embolization(0.9% of all patients ond 0.4% of all angiographic examinations) was about the same as has been reported in adults, but the clinical consequences were much milder, only one patient having documented transient neurologic symptoms. Also the angiographic appearance of the emboli differed from those described in adults. These differences may in part be due to the technique (general anesthesia with hyperventilation) but also to different reactions towards ischemia and to different types of emboli in children.