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Biomedical subjects

B C Lee

Publications and source records attributed to B C Lee.

At least 181 records · Page 10Linked to original sources
PubMed1986

Craniotomy versus transsphenoidal excision of large pituitary tumors: the usefulness of magnetic resonance imaging in guiding the operative approach.

Fifteen patients with large pituitary tumors were studied with computed tomography (CT) and magnetic resonance imaging (MRI). CT was performed using General Electric 8800 and 9800 scanners (General Electric Co., Medical Systems Division, Milwaukee, Wisconsin). MRI was performed utilizing a Technicare superconducting scanner (Technicare, Cleveland, Ohio) at 0.5 tesla. Based on the operative findings, the tumors were divided into two groups. Tumors in Group 1 (n = 12) were described by the surgeon as soft or partially necrotic and easily removed by suction and curettage. Tumors in Group 2 (n = 3) were firm and required sharp dissection or the laser for removal. The tumors were divided into four categories based on MRI signal: (a) isointense with surrounding brain on spin echo (SE) 30 and SE 90, (b) increased signal intensity on SE 30 and SE 90, (c) decreased signal intensity on SE 30 and increased signal intensity on SE 90, and (d) isointense signal on SE 30 and increased signal intensity on SE 90. All three of the firm tumors were isointense with brain on MRI appearance. The tumor consistency (firm vs. soft) was not differentiable on CT scan. The transsphenoidal approach is less satisfactory than craniotomy in cases of firm, fibrous pituitary tumors. Based on our preliminary data, if the MRI signal in the tumor is isointense, then the surgeon should be prepared to deal with a fibrous tumor and might elect a transcranial rather than a transsphenoidal approach.

Adult↗
PubMed1986

Periventricular hyperintensity as seen by magnetic resonance: prevalence and significance.

Periventricular hyperintensity was identified using long repetition and echo times in spin-echo magnetic resonance imaging of patients with white-matter disease (e.g., multiple sclerosis) caused by local demyelination and in hydrocephalic patients caused by transependymal migration of spinal fluid. A review of 365 consecutives studies revealed that some degree of periventricular hyperintensity is present in most patients (93.5%) regardless of diagnosis. Mild periventricular hyperintensity was seen in patients with no other evidence of intracranial pathology. Periventricular hyperintensity is a normal finding that should not be considered indicative of either demyelinating disease or hydrocephalus. More extensive and severe periventricular hyperintensity is associated with intracerebral pathology, but the finding often is nonspecific. For example, mild periventricular edema from hydrocephalus is impossible to differentiate from the increased periventricular hyperintensity seen in patients with multiple white-matter lesions. Thus, the pattern of periventricular hyperintensity has proven to be of limited value in the clinical assessment of hydrocephalic patients.

Adolescent↗
PubMed1985

Concurrent osteoblastoma and aneurysmal bone cyst of the ethmoid sinus: case report.

A unique case of osteoblastoma and aneurysmal bone cyst of the ethmoid sinus is reported. A causal relationship may exist between the two entities. The computed tomography appearance consisted of a dense lesion with a thin sclerotic rim containing a low-attenuation center, causing ethmoid sinus enlargement. Similar radiologic appearances are seen with other less rare pathologies.

Adolescent↗
PubMed1985

Results of revascularization and amputation in severe lower extremity ischemia: a five-year clinical experience.

Aggressive revascularization of the ischemic lower extremity in atherosclerotic occlusive disease by femoropopliteal (FP) and femorotibial (FT) bypass or profundaplasty (P), as indicated, has been advocated by some authors for all patients. Others have recommended primary amputation, particularly for tibial occlusive disease. To clarify this clinical dilemma, we reviewed the results of 547 procedures performed during the last 5 years: revascularization in 375 (69%) instances and below-knee amputation (BKA) in 172 (31%) cases. Bypass procedures were used in 246 cases: FP in 155 (64%) and FT in 91 (37%). Reversed autogenous saphenous vein (ASV) was used preferentially in 125 (51%) cases, whereas polytetrafluoroethylene (PTFE) was used in 121 (49%) cases. P was performed in 129 instances accompanied by inflow procedures in 92 (71%) of these cases. Cumulative limb salvage (LS) exceeded bypass patency in all categories and resulted in 2- and 5-year LS rates of 83% and 81% for FP with the use of ASV and 52% and 35% for PTFE. The LS rate for FT was 53% and 47%, respectively, for ASV and 20% and 15% for PTFE. Rest pain was successfully relieved by P in 99 cases (77%), whereas healing occurred in only 51% of cases with tissue loss. The perioperative mortality rate for revascularization was 3%; 42% of the group died during follow-up, death usually resulting from complications of atherosclerosis. Of the 172 BKAs, primary healing occurred in 80%, but the perioperative mortality rate was 13%. FP and FT bypasses are preferred procedures if ASV is available, whereas use of PTFE should be limited to FP bypasses only. Rest pain is relieved by P but tissue loss should prompt consideration for bypass. BKA should be considered in cases of severe tibial disease only in the absence of a suitable ASV, as the perioperative mortality rate is high and ultimate rehabilitation (64%) is limited.

Amputation, Surgical↗
PubMed1985

Sellar and juxtasellar lesion detection with MR.

We compared the effectiveness of magnetic resonance (MR) imaging and computed tomography (CT) in evaluating sellar and juxtasellar lesions. Fifty-five lesions were imaged with a Technicare 0.5-T superconducting MR imager and GE 9800 and 8800 CT scanners: 26 pituitary adenomas (including six microadenomas), six craniopharyngiomas, two empty sellae, five meningiomas, four optic chiasmal gliomas, five hypothalamic gliomas, two giant aneurysms, and one each of teratoma, gasserian ganglion neuroma, histiocytoma, cholesteatoma, and metastases. Although CT scans showed the abnormalities in most cases, MR was superior in delineating distortions of the optic chiasma and other suprasellar structures, and in demonstrating the status of the carotid arteries. MR can reveal fat, hematoma, and cyst and can be used to differentiate the pathologic features of many lesions. Microadenomas that do not enlarge the sella were not demonstrated with current MR techniques.

Adenoma↗
PubMed1985

MRI assessment of human callosal surgery with neuropsychological correlates.

MRI imaging using recovery and spin-echo techniques was carried out on three patients after surgical section of the corpus callosum to control intractable epilepsy. The scans revealed that the total callosotomy had been obtained in two patients, while partial sparing of splenial and rostral fibers was seen in the third.

Corpus Callosum↗
PubMed1985

MR imaging of syringomyelia and hydromyelia.

The relative effectiveness of plain computed tomography (CT), metrizamide CT, conventional myelography, and magnetic resonance (MR) imaging was compared for the examination of cystic spinal cord lesions. Intramedullary cavities in 18 patients were demonstrated by MR imaging: cavities were uncomplicated in 13 patients, associated with spinal tumors in two, and studied after occipital craniectomy for treatment of Chiari malformation and syringomyelia in two. Cavities were shown by MR imaging in all enlarged spinal cords, but a cavity was shown in only one of four small cords. The rostral limits of the cavities were demonstrated better than were the caudal extensions. Ventricular communication was not demonstrated. Chiari malformation was shown only in cavities that did not involve the medulla. Syringes associated with tumor were indistinguishable from uncomplicated cavities, but the tumor had abnormal signal on long spin-echo sequences in two cases. Cystic cord tumor (one case) had an inhomogeneous appearance. Caudal displacement of the cerebellar hemisphere through the surgical defect associated with compression of the fourth ventricle was shown in two cases after posterior fossa craniectomy. Thirteen patients were studied with metrizamide CT also. MR imaging proved to be as accurate as metrizamide CT in the diagnosis of intramedullary cavities that result in spinal cord enlargement, but it was less sensitive in detecting cavities within normal-sized or diminished spinal cords. It had the advantage that tumor tissue could be distinguished from associated syrinx cavities by differences in signal characteristics; and cerebellar ectopia was evaluated easily on sagittal MR views.

Arnold-Chiari Malformation↗
PubMed1985

The role of contrast arteriography in suspected arterial injuries of the extremities.

The records of 215 patients presenting with 218 penetrating or blunt injuries to the extremities from 1977 through 1983 have been reviewed. All patients presenting with pulsatile hemorrhage, expanding hematoma, or absent distal pulses were explored immediately. Patients with injuries in close proximity to a major artery but without classical signs of arterial injury were explored routinely from 1977 through 1980. Thereafter, similar patients were evaluated initially with contrast arteriography and explored only if arteriographic abnormalities suggested arterial injury. Routine exploration of proximity injuries has been compared with selective exploration based on contrast arteriography. Sixty-one patients (group 1) underwent routine exploration for proximity injuries. Vascular injuries were detected in ten (16%) patients, while 51 (84%) of the explorations were negative. Eighty-four patients (group 2) with proximity injuries were studied arteriographically. Ten patients (11.9%) were explored on the basis of abnormal arteriograms, and eight arterial injuries were confirmed. Two (2.4%) of the 84 patients in this group had negative explorations. The use of contrast arteriography enabled the authors to reduce their negative exploration rate from 84 to 2.4 per cent in the management of proximity injuries.

Adolescent↗
PubMed1985

Reoperation for sepsis.

A retrospective study of 50 patients undergoing reoperation for sepsis was performed to evaluate the ability of commonly available clinical and laboratory tests to predict the findings at reoperation and the outcome after operation. The influence of multiple organ failure on these parameters was also studied. No laboratory finding helped to predict operative findings. Computed tomographic scanning (80% accurate) was the most helpful radiographic procedure. A low total lymphocyte count and a high serum creatinine level both predicted a fatal outcome. No single organ failure or combination predicted a positive reexploration. Infection was found in 75 per cent of patients with multiple organ failure and 79 per cent of patients who did not have this syndrome. Patients having three-organ failure did have a significantly higher mortality. The mortality of a negative reexploration was 18.2 per cent, slightly lower than the 28.2 per cent mortality of patients with a positive exploration. No patient without organ failure died. The authors conclude that laboratory tests are not helpful in predicting the presence of infection on reexploration, that the decision to reoperate is one based primarily on clinical judgment, and that if reoperation is performed before the development of organ failure, the risk associated with a negative exploration is worth taking.

Adult↗
PubMed1985

Simultaneous determination of brachial and femoral arterial pressures during reactive hyperemia and papaverine vasodilation.

Accurate assessment of aortoiliac occlusive disease often requires direct intraarterial pressure determination. Since these measurements may alter systemic pressure, brachial arterial pressure (BAP) and femoral arterial pressure (FAP) were obtained simultaneously to quantitate these changes. BAP and FAP were measured at rest, and then during vasodilation produced by postischemic reactive hyperemia and intra-arterial injection of papaverine. The gradient between FAP and BAP was used to assess the significance of an aortoiliac stenosis. Sixty-eight observations were performed in 19 limbs. During reactive hyperemia (n = 28), BAP was 142 +/- 7 mm Hg, which was not significantly different from the baseline BAP of 142 +/- 5 mm Hg. However, during thigh tourniquet inflation, BAP increased significantly to 158 +/- 7 mm Hg. Following papaverine injection (N = 21) BAP was 144 +/- 8 mm Hg, which was significantly different from both the baseline BAP (150 +/- 6 mm Hg) and the preinjection BAP (156 +/- 6 mm Hg). Postischemic reactive hyperemia and papaverine vasodilation produced comparable brachial to femoral pressure gradients. Use of baseline BAP is recommended for calculating gradients during reactive hyperemia, since the BAP is significantly elevated during tourniquet occlusion. Simultaneous recording of brachial and femoral pressures is recommended with intra-arterial papaverine injections, since the BAP varies significantly throughout the examination.

Aortic Diseases↗
PubMed1984

Effect of a potent gonadotropin releasing hormone antagonist on pulsatile testosterone and gonadotropin secretion in the male nonhuman primate.

A potent gonadotropin releasing hormone (GnRH) antagonist [Ac-delta 3Pro1, pFDPhe2, DTrp3,6]-GnRH was given to adult male monkeys to determine the acute effect on pulsatile testosterone and gonadotropin secretion. Blood was drawn at 30 min intervals over 54 h without anesthesia using a mobile vest and tether assembly to support an indwelling catheter. After a 6 h control period, 0.1, 1.0, 2.0, 4.0 mg GnRH antagonist/kg bw in 1 ml corn oil sc, was given to intact adult male monkeys. The highest dose of GnRH antagonist decreased circulating testosterone within 6 h and for approximately 24-36 h duration. These data demonstrate that this GnRH antagonist can reduce serum testosterone both acutely and for intervals greater than 24 h and that the effective dose in intact animals is several-fold (up to 20 times) greater than in castrate animals.

Animals↗
PubMed1984

Occlusive vascular disease in asphyxiated newborn infants.

Six full-term severely asphyxiated newborn infants underwent evaluation with digital intravenous angiography. All infants were comatose and flaccid and had seizures, depressed brainstem function, and signs of intracranial hypertension. An initial brain CT scan revealed diffuse hypodensities and compressed ventricles. Follow-up noncontrast CT scans showed areas of increased attenuation. Digital intravenous angiography demonstrated venous sinus thrombosis in five infants, two of whom also had arterial thrombosis, and hypervascularity in the sixth infant. Our data document that occlusive vascular disease is a prominent feature of severe perinatal asphyxia.

Arterial Occlusive Diseases↗
PubMed1984

Posterior fossa lesions: magnetic resonance imaging.

Studies of 40 patients with abnormalities of the posterior fossa shown on magnetic resonance (MR) imaging were reviewed and compared with CT scans. Thirteen lesions were demonstrated on MR only. Twenty-four lesions were shown on CT but MR provided more data. Three lesions were better shown on CT than on MR. MR is superior to CT because of the lack of streak artifacts and better contrast discrimination. At least two imaging sequences are required for evaluation of the lesions.

Brain Diseases↗
PubMed1984

The assessment of skin blood flow in peripheral vascular disease by laser Doppler velocimetry.

The helium-neon laser Doppler (LD) is designed to measure skin blood flow velocity (SBFV). Flow velocity and pulse wave amplitude are expressed in millivolts (mv) relative to a zero-flow reference. The authors have reviewed their initial experience in ten persons (20 limbs) without peripheral vascular disease (PVD, group I) and nine patients (12 limbs) with severe PVD (group II). The finger, palm, great toe, and forehead had a significantly (P less than 0.05) greater flow velocity than the plantar and dorsal foot, distal and proximal leg, thigh, chest, arm, and forearm. Baseline and hyperemic SBFV, measured at the great toe, were compared in groups I and II. In group I, the baseline SBFV (mv, mean +/- standard error of the mean (SEM] in the great toe was 197 +/- 38 compared with 67 +/- 12 in group-II patients (P less than 0.05). The pulse wave amplitude (mv, mean +/- SEM) was 77 +/- 14 in group I and 5.4 +/- 1.1 in group II (P less than 0.05). The time to maximal hyperemic response (seconds, mean +/- SEM) in group I was 18 +/- 1.5 compared with 150 +/- 14 in group II (P less than 0.05). LD is a sensitive indicator of changes in SBFV, allowing differentiation between normal persons and patients with PVD. The LD tracing in patients with PVD is characterized by a baseline SBFV that is significantly less than normal and also by the attenuation or absence of pulse waves. The diagnostic accuracy is enhanced by the use of reactive hyperemia.

Adult↗