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Biomedical subjects

G R Ramsby

Publications and source records attributed to G R Ramsby.

At least 19 recordsLinked to original sources
PubMed1999

Brain morphometric analysis in neurofibromatosis 1.

RATIONALE AND OBJECTIVES: To investigate the relationships between brain and skull base growth in patients with neurofibromatosis 1 (NF1) compared with healthy control subjects using brain magnetic resonance imaging (MRI) for morphometric analysis. METHODS: Evaluated patients included children who underwent T1- and T2-weighted or dual-echo proton density axial and T1-weighted sagittal brain MRI from January 1, 1988, to December 31, 1995. Study subjects (n = 27) received a diagnosis of NF1 by accepted National Institutes of Health clinical criteria and were compared with an age- and sex-matched control group (n = 43). Twenty-four predetermined ventricular and brain parenchymal dimensions and area calculations were evaluated. Data were analyzed using 2-tailed t tests, chi2 analysis, analysis of variance, and analysis of covariance adjusted for age and sex. Correlational analyses with respect to subject type and age were performed separately. RESULTS: There were 27 patients (20 boys, aged 1.0-17.7 years; mean age, 8.8 years) and 43 controls (22 boys, aged 0.1-17.7 years; mean age, 5.9 years). The mean ages between groups (boys, girls, and totals) were not statistically different. Significant differences were appreciated for 6 of 24 measures. Patients with NF1 had a significantly larger bicaudate width (P = .002), biatrial width (P<.001), and biparietal diameter (P = .003), but not hemispheric length. They also had significantly increased iter measures (P = .004), descending sigmoid sinus (P<.001), and an age-specific increase in brainstem height (P = .03) not seen in controls. CONCLUSIONS: Patients with NF1 experience dynamic changes in brain morphometry, resulting in a predominant lateral volume expansion of the supratentorial compartment and an increasing velocity of brainstem growth as they age. These data underscore brain-region-specific parenchymal overgrowth potential.

Adolescent↗
PubMed1997

Dosimetry and cost of imaging osseointegrated implants with film-based and computed tomography.

Thermoluminescent dosimeters were used to measure radiation doses at craniofacial sites in a tissue-equivalent phantom during film-based multidirectional tomography with the Tomax Ultrascan (Incubation Industries, Ivyland, Pa.) and during computed tomography with the Elscint Excel 2400 (Elscint Corp., Tel Aviv, Israel). Mean absorbed doses for presurgical mandibular and maxillary canine and molar implant assessments were converted to equivalent doses, which were then multiplied by published weighting factors and summed to give effective doses. The computed tomography device consistently delivered higher doses than the Tomax Ultrascan to all anatomic locations; the differences were most pronounced when only one or two implant sites were evaluated. The reasons for the dose disparities are considered both anatomically and procedurally. A survey of examination cost revealed film-based multidirectional tomography to be less expensive than computed tomography.

Dental Implantation, Endosseous↗
PubMed1997

Concurrence of Graves' disease and dysplastic cerebral blood vessels of the moyamoya variety.

We describe two Caucasian women with the concurrence of Graves' disease and the moyamoya phenomenon (radiological evidence of collateral cerebral blood vessels like "puffs of smoke" due to cerebrovascular occlusive disease). One patient presented with acute cerebrovascular ischemia due to Moyamoya disease shortly after radioactive iodine therapy for Graves' disease and the second presented with Graves' disease 10 years after being diagnosed with moyamoya dysplastic cerebral vessels. The optimal treatment of hyperthyroidism in these patients is unknown; however, careful control of the hyperthyroidism by any modality seems reasonable. Our limited experience suggests that antithyroid drugs and radioactive iodine therapy are rational options. Thyroidectomy appears to be a safe therapeutic alternative, although long-term efficacy may be difficult to assure. Both of our patients had to be treated twice for hyperthyroidism. Whether Graves' disease and Moyamoya coexist because of an aggressive autoimmune mechanism is a concept that remains to be settled.

Adult↗
PubMed1995

Sensitivity of percutaneous endoscopy compared with ultrasonography in the detection of residue or mucosal lesions after topical gallbladder stone dissolution.

BACKGROUND: Early gallstone recurrence in some patients after "successful" percutaneous topical dissolution may be due to residual debris. An endoscope small enough to be introduced without dilating the existing percutaneous track was used for gallbladder examination after stone dissolution. METHODS: The sensitivity of gallbladder endoscopy was compared with ultrasonography and double-contrast cholecystography for the detection of residual debris or mucosal lesions in 18 patients who underwent percutaneous topical dissolution. All examinations were performed before catheter removal and after the gallbladder was deemed stone-free by the traditionally employed technique of single-contrast cholecystography. RESULTS: Residual debris was detected in only one patient by ultrasonography and in none of the 18 patients by double-contrast cholecystography, yet endoscopy showed stone fragments ranging from 1 to 3 mm in 13 of the 18 patients. In all these patients, catheter repositioning and additional solvent perfusion resulted in elimination of the debris as assessed endoscopically. Two patients had endoscopically detected erosions. Double-contrast fluoroscopy found only one of these, whereas ultrasonography detected neither. CONCLUSIONS: Percutaneous gallbladder endoscopy is a more sensitive imaging modality for the detection of residual stone debris or mucosal lesions after gallstone dissolution.

Cholecystography↗
PubMed1995

Brain morphometric analysis in achondroplasia.

RATIONALE AND OBJECTIVES: We undertook an MRI brain morphometric analysis to investigate the relationships between brain and skull base growth and clinical function in patients with achondroplasia as compared to normal controls. METHODS: Patients selected for evaluation included pediatric patients who underwent T1 and T2 or dual-echo, proton-density axial T1- and T2-weighted and T1 sagittal brain MRI during 1988 to 1992. Study subjects (n = 11) were diagnosed with achondroplasia by clinical and radiologic criteria and compared to an age- and gender-matched control group (n = 25). Twenty-four predetermined ventricular and brain parenchymal dimensions and area calculations were evaluated. Data were analyzed using two-tailed t tests, chi-squared analysis, ANOVA, and ANCOVA, adjusting for age and sex. Correlational analyses with respect to subject type and age were done separately. RESULTS: There were 36 patients (11 subjects with 15 MRI examinations, mean age 2.3 years, and 25 controls with 26 MRI examinations, mean age 3.0 years). Significant differences existed for 11/17 measures. Achondroplasts had a significantly larger bifrontal width (p < 0.0001), bicaudate width (p < 0.0001), frontal horn diagonal length (p < 0.05), biatrial width (p < 0.0001), biparietal diameter (p < 0.05), and iter to incisural line distance (p < 0.0001). Achondroplasts had significantly smaller frontal lobe depths (p < 0.01), optic tract angles (p < 0.0001), foramen magnum diameters (p < 0.0001), and sinojugular transition zones (p < 0.05). There were no differences in brainstem heights or fourth ventricular widths between achondroplasts and controls. Furthermore, with respect to age, frontal lobe depth was smaller when compared to controls and the descending sigmoid sinus area became increasingly larger. CONCLUSIONS: Achondroplastic subjects experience dynamic changes in brain morphometry resulting in a rostral displacement of the brainstem with gradual compression of the frontal lobes due to enlargement of the supratentorial ventricular spaces commensurate with an increase in venous sinus distension.

Achondroplasia↗
PubMed1994

Conscious sedation for imaging and interventional studies.

Some radiology patients may need medication to decrease anxiety and control pain. In this comprehensive article, the authors describe quality care for patients receiving conscious sedation, effective ways of delivering this service and detailed descriptions of the conscious sedation program at a northeastern university hospital. A valuable chart of recommended drugs, dosages, considerations and possible side effects is included.

Adult↗
PubMed1993

Familial band heterotopias simulating tuberous sclerosis.

We report the clinical and neuroimaging findings of a mother and daughter with seizure disorders and band heterotopias seen on magnetic resonance imaging studies. These clinicoradiologic findings simulate those for a diagnosis of tuberous sclerosis complex. Clinicians should be aware of this migrational anomaly and its neuroimaging characteristics, as well as the potential for this specific migrational anomaly to be genetically transmitted.

Adolescent↗
PubMed1989

Adrenocorticotropin-independent bilateral macronodular adrenal hyperplasia: an unusual cause of Cushing's syndrome.

Inappropriate ACTH secretion with bilateral diffuse or macronodular adrenal hyperplasia is the most common cause of Cushing's syndrome. This report describes a patient with Cushing's syndrome and feminization due to ACTH-independent bilateral macronodular adrenal hyperplasia. A 47-yr-old black man presented with Cushingoid features, diabetes mellitus, hypertension, impotence, and gynecomastia. Urinary cortisol and 17-hydroxycorticosteroid excretion were 94 nmol/mmol creatinine (normal, less than 32) and 5.8 mumol/mmol creatinine (normal, 0.6-3.6), respectively. Both decreased by less than 30% after administration of dexamethasone (8 and 16 mg/day), and urinary 17-hydroxycorticosteroid excretion did not increase after metyrapone (750 mg, orally, every 4 h for six doses). Plasma ACTH was undetectable (less than 1 pmol/L) and was not stimulated by administration of metyrapone or ovine CRH. Serum testosterone was 5.2 nmol/L (normal, 7-30), FSH was 5 U/L (normal, 3-18), LH was 2.8 U/L (normal, 1.5-9.2), and estrone was 767 pmol/L (normal, 55-240). Both adrenal glands were enlarged, with a total weight of 86 g (normal, 8-10), and contained multiple nodules (diameter, greater than 0.5 cm) composed of two active cell types, one of which was also observed between the nodules. Cushing's syndrome with feminization due to ACTH-independent bilateral macronodular adrenal hyperplasia is an unusual process of unknown etiology that should be included with the other known causes of Cushing's syndrome.

Adrenal Glands↗
PubMed1988

Renovascular hypertension in moyamoya syndrome. Therapeutic response to percutaneous transluminal angioplasty.

Moyamoya ("puff of smoke") syndrome is a disease of children and young adults caused by fibromuscular dysplasia of the internal carotid and proximal cerebral arteries and is rarely associated with hypertension. We report a 34-year old woman with moyamoya syndrome who presented with symptomatic severe hypertension associated with unilateral renal artery stenosis. The patient underwent percutaneous transluminal angioplasty of the right renal artery with subsequent improvement in blood pressure control on reduced, and later, no antihypertensive therapy. This case illustrates that moyamoya syndrome may be an intracranial manifestation of a systemic arterial disorder. Renal artery stenosis may, in appropriate cases, be managed by percutaneous transluminal angioplasty.

Adolescent↗
PubMed1987

Computerized tomography of the patellofemoral joint before and after lateral release or realignment.

Computerized tomography (CT) provides an accurate diagnostic tool for evaluating tilt and subluxation of the patella. Using a previously described technique, this study reviews 62 computerized tomograms, including those of 21 patients before and after lateral release or anteromedial tibial tubercle transfer. One patient was evaluated before and after soft-tissue realignment of the patella. Additional CT studies were evaluated to establish the most appropriate reference line for determining patellar tilt. Results show that lateral retinacular release effectively reduces abnormal patellar tilting as determined by CT. Anteromedial tibial tubercle transfer similarly reduces abnormal tilt. Patellar subluxation may improve substantially following either lateral release or anteromedial tibial tubercle transfer, but this study suggests that correction of subluxation is less consistent than reduction of abnormal tilt with tibial tubercle transfer or lateral release alone. Once articular degeneration has progressed to the point of facet collapse, lateral release fails to restore normal tilt.

Adult↗
PubMed1987

Skeletal measurements using a flying spot digital imaging device.

A flying spot digital imaging unit was devised to measure skeletal length and angles. This device uses a spinning chopper wheel and fixed slit collimator in front of a conventional X-ray tube to produce a scanning pencil beam that passes through the patient and onto an electronic detector. The beam scans the patient transversely and the device moves longitudinally, creating a digital image with a skin dose of less than 2 mrad (0.02 mGy). Patients can be imaged both when upright and when recumbent. A large field of view makes it possible for the entire length of the spine or lower extremities to be included in a single image. Built-in computer algorithms are used to make measurements of skeletal lengths and angles. The accuracy of the digital device was tested by making measurements of known angles and lengths using protractors and rulers. Skeletal measurements were then made on a number of patients. Interobserver error was tested using both patient and nonpatient images. The following patient measurements were made: Cobb angle in 166 patients with scoliosis; knee joint angles in 120 patients undergoing knee surgery; lower extremity lengths in 78 patients with length inequalities; bony fragment angulation and displacement in 30 patients with healing fractures. These studies have shown the device to be accurate with low interobserver error, while delivering much lower patient dose than more conventional methods. The ability to manipulate window levels and widths enables visualization of thick and thin body parts on the same image. Our experience both in the laboratory and with patients has been encouraging, and the method appears to have several advantages over more conventional techniques.

Bone and Bones↗
PubMed1986

Computed tomographic classification of patellofemoral pain patients.

A preliminary study was undertaken at the University of Connecticut Sport Injury and Knee Clinic to evaluate a small series of patients with peripatellar pain as well as a group of asymptomatic controls. With the encouragement of the initial results, this experience has been expanded to include a larger number of patients. Based on CT criteria of subluxation and tilt, it has become possible to categorize patellofemoral tracking abnormalities. The purpose of this article is to clarify further a classification system for patellofemoral pain patients.

Adolescent↗
PubMed1986

The evaluation of patellofemoral pain using computerized tomography. A preliminary study.

There are well-recognized limitations of conventional axial radiographs of the patellofemoral joint in assessing patients with peripatellar pain, particularly in the first 20 degrees of knee flexion. Computerized tomography (CT) was used, therefore, to evaluate 20 patients with persistent patellofemoral pain and ten asymptomatic volunteers. Multiple midpatellar images were obtained between zero degrees and 30 degrees -40 degrees (sometimes 40 degrees) of flexion, with and without maximal quadriceps contraction. Three distinct patterns of malalignment were identified. When compared to controls, 11 patients had lateralized patellae based on high-congruence angles in extension. With progressive flexion to 30 degrees, all but one reduced into the trochlea. This group was subdivided into those lateralized with or without associated patellar tilting. There were seven patients whose patellae progressively tilted between zero degrees and 30 degrees of flexion while remaining centered in the trochlea. Anatomic differences demonstrated by CT appear to be a factor in distinguishing these groups. Computerized tomography may be the optimal method of radiographically evaluating the patellofemoral joint. Patients have been identified with lateralized patellae in extension that subsequently become congruent by 30 degrees of flexion and therefore may not be appreciated on traditional radiographs. An awareness of different patterns of malalignment is a significant advantage of computerized tomography when planning selective surgical realignment for these patients.

Adolescent↗
PubMed1985

Hypertension from isolated thoracic aortic coarctation associated with neurofibromatosis.

A 14-year-old boy presented with hypertension and symptomatic cervical root neurofibromatosis. Isolated thoracic aortic coarctation and large collaterals adjacent to the cervical spine were identified. Surgical correction of the coarctation allowed safe excision of the neurofibroma and reversal of hypertension. Hypertension in the presence of neurofibromatosis requires evaluation of a number of correctable etiologies.

Adolescent↗