Multicapillary mixer of solutions.

A mixer made from a bundle of glass tubules can mix two solutions within 30 microseconds, with a total-solution flow rate of 1.33 milliliters per second. One solution passes through the interstices of the bundle; the other moves through the lumens of the tubes.

Automatic reservoir for serial pipetting.

An automatic reservoir for serial pipetting was constructed and used in radioimmunoassay determinations. This device features negligible priming volume, minimal solution loss, and lowered overall cost. In our experience, it has proven valuable when used with an automatic pipetting station. This apparatus has not affected the precision or accuracy of the procedure. It has made it possible to economize on costly antibody reagents supplied with radioimmunoassay kits, especially in use with low-volume assays.

Evaluation of bone graft viability.

Radionuclide bone single photon emission computed tomography (SPECT) scintigraphy is an excellent method for the assessment of the vascular patency and bone viability. The scintigraphic findings are important in the management of microvascularized bone grafts used in the reconstruction of bone defects. These living bone grafts are necessary when the blood supply at the host site has been compromised as a result of radiation therapy or when the bone defect is greater than 6 cm. Bone scintigraphy is unique because the uptake of radiopharmaceutical is dependent both on an adequate delivery system and a living network of osteocytes. SPECT scintigraphy provides improved imaging characteristics and structural detail of the grafted bone. Eleven patients with microvascularized bone grafts to the mandible demonstrated marked bone reaction of the entire bone graft in the postoperative period. The accumulation of radiolabelled 99mTc methylene diphosphonate (MDP) correlated extremely well with postoperative findings and clinical response. SPECT bone scintigraphy was a safe, simple and effective method for the assessment of both patency of anastomosed blood vessels and the metabolic viability of the microvascularized bone graft.

Experimental pulmonary infarction in a pig model.

RATIONALE AND OBJECTIVES: The authors sought to develop a reliable animal model for experimental pulmonary infarction, to evaluate it with radiologic-pathologic correlation, and to determine the use of high-resolution computed tomography (HRCT) in monitoring parenchymal lung damage due to infarction. METHODS: Selective left lower lobe pulmonary artery occlusion was performed in seven Yorkshire pigs with transcatheter silicone elastomer injection. After occlusion, 99m technetium (99mTc) macroaggregated albumin perfusion lung scans and sequential in vivo HRCT lung scans were obtained from days 0 to 46. The in vivo radiologic findings were correlated with specimen radiography, specimen HRCT, and histologic findings. RESULTS: A complete and permanent arterial occlusion was achieved, involving up to three orders of branching distal to the catheter. An anatomically defined perfusion defect was seen on 99mTc lung scans corresponding to the occluded area. HRCT changes consisted of confluent densities progressing to mixed alveolar and interstitial opacities within the first week after embolization. In the follow-up period, marked parenchymal clearing was observed. In all cases after pulmonary artery occlusion, the histologic findings were characteristic of pulmonary infarction and demonstrated alveolar edema, hemorrhage, limited alveolar wall damage, and septal thickening followed by residual fibrosis. CONCLUSION: Using this model, it is feasible to produce pulmonary infarction in the pig which may potentially be useful to study the pathophysiologic and radiologic changes of pulmonary infarction.

Pulmonary scintigraphy in elastase-induced emphysema in pigs. Correlation with high-resolution computed tomography and histology.

OBJECTIVES: The objective of this study is to evaluate the mild physiologic changes of elastase-induced pulmonary emphysema in the pig by radionuclide scintigraphy and to correlate these findings with high-resolution computed tomography (HRCT) and histologic examination. METHODS: Eight 7- to 12-week-old Yorkshire pigs were studied. Perfusion and ventilation studies were performed in six pigs at 1- or 2-week intervals after elastase instillation. HRCT was simultaneously performed for correlation with radionuclide scintigraphy. For the perfusion scans, technetium 99m (99mTc) macroaggregated albumin (MAA) was used, and both planar and single-photon emission CT (SPECT) images were obtained. Ventilation studies were performed with xenon-133 gas with dynamic sequential imaging. RESULTS: Histopathologic findings demonstrated dilatation and destruction of the alveoli and were similar to those previously reported by the authors. The SPECT perfusion images showed significantly impaired perfusion of the involved segment of the lung, corresponding to the region where elastase was instilled. The planar xenon-133 ventilation scintigraphy did not show abnormal air trapping. The mild emphysema induced with elastase manifested as decreased and impaired perfusion with no detectable ventilation abnormalities. The sensitivity of SPECT perfusion studies for the detection of the mild changes of elastase-induced pulmonary emphysema were higher than that of HRCT. CONCLUSIONS: The perfusion studies reflect functional or physiologic changes in contrast to structural changes seen on HRCT. This pig model was valuable to study the scintigraphic manifestation of elastase-induced pulmonary emphysema.

Radiation-induced lung injury using a pig model. Evaluation by high-resolution computed tomography.

RATIONALE AND OBJECTIVES: To assess the early phase of radiation-induced lung injury using high-resolution computed tomography (CT) under experimental conditions and to perform precise CT-pathologic correlation. METHODS: Five Yorkshire pigs received a single dose of 12.5 Gy to the right lower lung. Computed tomographic images were obtained at 2-week intervals. The animals were killed after follow-up periods of 4-16 weeks. The lungs were removed, inflated, fixed, dried, and sliced corresponding to the CT sections. Computed tomography, specimen radiography, and histologic findings were correlated. RESULTS: Various CT findings were observed during the first 16 weeks, including ground-glass opacity, discrete consolidation, patchy consolidation, thickened interlobular septum, and bronchovascular bundle. Ground-glass opacity was associated with thickened alveolar wall and scattered tiny fibrotic foci. Thickened interlobular septum and bronchovascular bundle were the results of fibrosis adjacent to these structures. Discrete consolidation correlated with intraalveolar edema with hemorrhage and infiltration of inflammatory cells. CONCLUSIONS: High-resolution CT correlated well with pathology of the lung due to radiation injury as verified by precise radiologic-pathologic correlation.

Feasibility of total thyroidectomy in the treatment of thyroid carcinoma: postoperative radioactive iodine evaluation of 140 cases.

The objective of this study was to evaluate our experience with so-called total thyroidectomy. Fifty cases (the retrospective group) had been operated on before the start of the study and had been on thyroid replacement therapy; this was discontinued, thyroid-stimulating hormone was administered, and iodine-131 studies were performed. Ninety cases (the prospective group) were evaluated 3 or more weeks postoperatively with no thyroid hormone having been administered. All patients were given 50 microcuries of iodine-131 and uptake studies were performed 24 hours later. All the patients were evaluated at a time when it was believed that practically all circulating hormone secreted by the thyroid gland before its removal had been metabolized or excreted from the body. If the patients with iodine-131 uptakes only in the region of the pyramidal lobe are considered to have had total thyroidectomy, we find that 85.7% of the patients studied had an uptake of less than 1.5%, and 96.4% had an uptake of less than 2.5%. There is increasing evidence to indicate that total thyroidectomy is the procedure of choice in the treatment of differentiated thyroid carcinoma. The present study indicates that with proper technique, total resection of the thyroid gland is feasible in nearly all cases of thyroid carcinoma.

Preoperative localization of parathyroid adenomas.

During a 12-month period, 64 patients were operated on for primary hyperparathyroidism. Sixty-one had single adenomas and 3 had double adenomas. Preoperative imaging was used to localize the adenomas. Half of the patients (32 of 64) had magnetic resonance, thallium-201/technetium-99m subtraction scintigraphy, and high-resolution ultrasonography; the other 32 patients had 1 or 2 of the imaging modalities. Sensitivity and specificity of magnetic resonance imaging was 82 percent and 97 percent, respectively; the sensitivity and specificity of the other two modalities was 59 and 98 percent for subtraction scintigraphy and 73 and 98 percent for ultrasonography. The use of preoperative imaging facilitated surgical exploration, reduced operating time, and resulted in an increased number of successful operations. There were no negative explorations in this series as compared with 19 negative explorations (2.6 percent) in our prior experience with 720 operations.

111Indium-tropolone labeled human PMNs: a rapid method of preparation and evaluation of labeling parameters.

Pure polymorphonuclear leukocytes (PMNs) have been isolated from a small amount of human blood by a single-step density gradient centrifugation method using a commercially available Ficoll-Hypaque mixture of density 1.114. The cells were labelled with [111In]tropolone in both buffer and plasma. Cell viability, ability to generate superoxide anion, and chemotaxis were found to be unaltered both before and after labeling. The optimum tropolone concentration for labeling was found to be 1 X 10(-4) M. Labeling efficiency was higher at 37 degrees C than at room temperature. Compared to [111In]oxine, tropolone preparation both in buffer and plasma resulted in consistently higher yields. Preliminary experiments of in vivo cell viability of the labeled PMNs were carried out in rabbits. The ability of the cells to localize in experimentally produced inflammatory lesions was found to be intact. The method of cell separation and labeling described has been found to be simple and rapid and could easily be incorporated in routine nuclear medicine laboratory practice.

Visualization of a pseudomeningocele on isotope cisternography.

Pseudomeningocele, a hernial protrusion of the meninges, most commonly forms in wounds that have been incompletely closed at surgery. They are frequently seen with hydrocephalus, with or without increased intracranial pressure. The authors present a case of an incidental finding of a posterior fossa pseudomeningocele seen on cisternography that was performed because of postoperative hydrocephalus after removal of a cerebellar astrocytoma.

Dental radiographic exposure normalization program (DENT). The experience in Nassau County, NY.

A Federally sponsored program for reducing unnecessary exposures from dental radiographic procedures is monitored over four years. The results are encouraging.

Radionuclide diagnosis of bleeding Meckel's diverticulum in children.

The preoperative diagnosis of rectal bleeding due to Meckel's diverticulum in children has major difficulties when only standard clinical and radiographic technics are utilized. During the past three years we have done 70 studies with Tc99m pertechnetate for this suspected diagnosis using scintillation camera imaging and computer analysis. Five positive cases were identified and all verified at surgery. No false positives were noted. We believe this to be a safe and available procedure that should be considered a primary diagnostic modality in the investigation of young children with suspected bleeding Meckel's diverticulum.

Diagnosis and management of complications of percutaneous nephrolithotomy.

The therapeutic management of the complications of percutaneous nephrolithotomy (PNL) depends on the early recognition of these complications. A review of 720 cases revealed the incidence of significant complications to be less than 4%. An algorithm was developed as a guideline for the diagnosis and management of complications of PNL. Early complications included transient bleeding (83 cases), extravasation of urine (52 cases), significant infection (11 cases [2 with septicemia and shock]), and migration of stone fragments into the retroperitoneum (7 cases). Nonrenal complications were present in less than 6% of these patients. These included pleural effusions or pneumothorax (24 cases) and lung atelectasis (19 cases). Late complications were seen in less than 2% of the patients. These included stricture of the ureter with obstruction (5 cases), A-V fistula with or without pseudoaneurysm (7 cases), and subcapsular hematoma (1 case). Therapeutic management included improvement of technique to the use of antibiotics to treat infection. The use of proper drainage and the placement of stent or catheter in the treatment and prevention of further complications has become an integral part of the algorithm for the treatment of complications of PNL. This algorithm recommends the proper diagnostic modality for the detection and evaluation of the extent of the complication. Once detected, the complications of PNL can be minimized with limited permanent changes.

Pneumatic dilation in patients with achalasia with a modified Gruntzig dilator (Levine) under direct endoscopic control: results after 5 years.

From 1985 to 1990, 62 patients have undergone pneumatic dilatation with the modified Gruntzig (Levine) dilator in the treatment of achalasia. A single dilatation with a 30-mm balloon dilator was successful in 85% of the patients. Nine patients required additional procedures. One elected for operative surgical repair, and eight patients underwent a second dilatation with a 35-mm balloon dilator. One patient required a third procedure with a 40-mm dilator. Two patients developed dysphagia for solids after pneumatic dilatation, and did not demonstrate delay or obstruction to the passage of technetium on follow up study. We have described this syndrome as dysfunctional dysphagia, and believe that it is related to the rapid ingestion of a food bolus, and is relieved by eating smaller portions at a slower rate. This is to be differentiated from reflux esophagitis and/or stricture secondary to reflux. One patient required bougie dilatation of a stricture, and three other patients were treated with omeprazole, ranitidine, or antacids with relief of reflux symptoms. The safety and efficacy of the procedure of pneumatic dilatation under direct endoscopic control with the modified Gruntzig dilator has been demonstrated in patients from 8 to 93 yr old, and in patients who have had prior Heller myotomy.

Postoperative radioactive iodine evaluation of total thyroidectomy for thyroid carcinoma: reappraisal and therapeutic implications.

The records of 430 patients who underwent total thyroidectomy with radioactive iodine (RAI) uptake studies performed postoperatively were reviewed. Indications for the administration of an ablative dose of iodine 131 are given. The majority (85.4%) had no or low (less than 2%) evidence of focal uptake and therefore were not treated with ablative doses of iodine 131. RAI scanning is necessary postoperatively to determine the completeness of the surgical procedure and to detect residual or metastatic disease. Small foci of residual disease or occult distant metastases can be adequately treated with therapeutic doses of RAI. Nodal or distant metastases that become clinically evident following thyroidectomy are usually not successfully treated with RAI.

Morphologic and functional changes in the kidney after percutaneous nephrosto-lithotomy.

Morphology and function of the kidney were studied before and after percutaneous stone extraction in 33 patients with unilateral calculus disease to assess damage secondary to the extraction procedures. Anatomic changes were studied using excretory urography before the procedure and at 3 to 6 months postoperatively, and using nephrostograms and noncontrast nephrotomograms several days after the procedure. Renal function was evaluated with radionuclide renography both before surgery and at either 4 to 6 weeks or about 1 year postoperatively. Six patients had early changes detected clinically and with nephrostograms, but only three of these had abnormalities on delayed excretory urography. Significant changes in renal function were found only in those patients who had clinically detectable complications (p less than 0.05), in one case before symptoms were manifest.