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Biomedical subjects

R E Koehler

Publications and source records attributed to R E Koehler.

At least 19 recordsLinked to original sources
PubMed1998

Expandable metal stents for the treatment of colonic obstruction: techniques and outcomes.

BACKGROUND: Acute left-sided colonic obstruction is a surgical emergency whose management is controversial. Because experience using expandable metal stents for relief of this type of obstruction is limited, we evaluated their effectiveness, feasibility, safety, and outcome. METHODS: Twenty-five patients with acute colorectal obstruction underwent placement of various metal stents under fluoroscopic and endoscopic guidance. On an intent-to-treat basis, stents were placed for decompression before one-stage surgical resection in 10 patients and palliatively in 15 patients. Two preoperative patients had unresectable malignant disease, and stents were left for palliation resulting in 17 palliative and 10 preoperative patients for analysis. RESULTS: Stent placement was technically successful in 94% of patients. Overall effectiveness in relieving obstruction was 85% (palliative 82%, preoperative 90%). In the palliative group, stent duration ranged from 2 to 64 weeks (mean 17.3 weeks). Major complications occurred in 7 patients (30%). CONCLUSIONS: Expandable metal stents are a feasible, effective adjunct and alternative to surgery for acute colorectal obstruction.

Acute Disease↗
PubMed1998

Hysterosalpingography with videofluoroscopy: effect on radiologic practice in an academic medical center.

RATIONALE AND OBJECTIVES: The authors attempted to determine whether videotaping the fluoroscopic portion of hysterosalpingography would result in changed diagnoses or an increase in diagnostic confidence. MATERIALS AND METHODS: Ninety-nine consecutive outpatients underwent routine hysterosalpingography. The fluoroscopic portion of the examination was captured on videotape. Two consecutive interpretations of each hysterosalpingogram were made by attending radiologists. First, spot radiographs were interpreted alone. Second, these images were viewed along with videofluoroscopy. Concordance of and confidence in findings for the two interpretations were assessed with the two-tailed Fisher exact test. RESULTS: Interpretations of spot radiographs alone and with videofluoroscopy were in agreement in 92 of 99 uterine examinations and 164 of 198 tubal examinations. For uterine examinations classified as normal, interpretations of spot radiographs and videofluoroscopy were in agreement in 56 of 57 cases; there was no change in confidence with review of videofluoroscopic images. For uterine examinations interpreted as abnormal, agreement was noted in 36 of 42 cases (P = .04), and confidence increased with videofluoroscopy in 10 of 42 cases (P = .00001). With normal tubal findings, interpretations agreed in 94 of 118 cases, and confidence increased in 56 of 118 cases (P = .002). With abnormal tubal findings, interpretations agreed in 70 of 80 cases, and confidence increased in 20 of 80 cases (P = .002). When findings with and without videofluoroscopy were discordant, confidence was always higher after review of video-fluoroscopic images. CONCLUSION: Review of videofluoroscopic images obtained during hysterosalpingography increases the accuracy and confidence of diagnoses compared with review of spot radiographs alone.

Academic Medical Centers↗
PubMed1997

Treatment of colonic obstruction with expandable metal stents: radiologic features.

OBJECTIVE: The purpose of this prospective study was to evaluate the efficacy of expandable metal stents for colonic decompression in patients presenting with acute malignant obstruction and to describe the associated radiographic findings. SUBJECTS AND METHODS: Using both fluoroscopic and endoscopic guidance, we placed expandable metal stents within the colons of 13 patients presenting with acute malignant obstruction. Stents were placed in four patients to permit a standard bowel cleansing before surgical resection with primary anastomosis. In the other nine patients, stents were placed for palliation of nonresectable tumors, obviating colostomy. Outcomes and complications were analyzed. The radiologic aspects of procedural planning, stent placement, assessment after placement, and detection of complications were evaluated. RESULTS: Of the four surgical candidates who were successfully resected with primary anastomosis, two received incomplete bowel cleansing because of stent migration with recurrent obstruction. Eight of the nine patients who had stents placed for palliation of nonresectable tumors had relief of acute obstruction. Complications in this group included two perforations, one that required immediate colostomy and one that was self-limited and conservatively treated. Two other patients of the eight developed early stent obstruction, requiring colostomy in one. The other patient who had a stent placed for palliation of a nonresectable tumor declined further treatment. Contrast-enhanced enema examination proved useful in assessing the suitability of lesions for stent decompression, directing the choice of stent type and the most appropriate position for the patient during the stent placement. Immediately after stent placement, plain abdominal radiographs and water-soluble contrast enema examinations helped us verify stent position and patency. CONCLUSION: These results suggest that placement of expandable metal stents in patients presenting with acute, malignant colonic obstruction is a viable alternative to colostomy and can potentially decrease morbidity and mortality. Radiologic assessment before, during, and after stent placement plays an integral role in the management of patients undergoing stent decompression of the colon.

Acute Disease↗
PubMed1997

Timed barium swallow: a simple technique for evaluating esophageal emptying in patients with achalasia.

OBJECTIVE: Our purpose was to define a simple technique for timing a barium swallow by which radiologists can assess esophageal emptying in patients with achalasia before and after minimally invasive therapy. Our purpose was also to determine the best method of quantifying the degree of emptying using this timed technique. MATERIALS AND METHODS: In the barium swallow technique, upright frontal spot films of the esophagus are obtained at 1, 2, and 5 min after ingestion of 100-200 ml of low-density (45% weight in volume) barium sulfate (volume of barium determined by patient tolerance). Forty-two of these barium swallows done by 23 patients with achalasia were retrospectively reviewed. The examination served either as a baseline study or as a 1-month follow-up study after patients had undergone pneumatic dilatation or Clostridium botulinum toxin injection. The spot films were digitized, and a region of interest was drawn around the column of barium by two observers. The change in area seen in the region of interest on the 1- and 5-min films served as the gold standard for percentage of emptying. The spot films were then analyzed by four other observers, each of whom independently, subjectively, and qualitatively estimated the percentage of emptying between the 1- and 5-min spot films. Percentages were divided into quintiles. On a separate occasion, each of these four observers also independently measured the height and width of the barium column on the 1- and 5-min spot films. The product of height times width seen on the 1- and 5-min films became the quantitative estimate for percentage of emptying. RESULTS: We found no statistically significant difference between the percentage of emptying as measured on the digitized images by the two observers and the height-times-width calculations or qualitative emptying percentage as estimated by the four observers. Interobserver agreement for the area evaluated on the digitized films as well as the height-times-width measurements and qualitative estimates of emptying was almost perfect (the correlation coefficients being 0.99, 0.87, and 0.93, respectively). CONCLUSION: The timed barium swallow is a simple and reproducible technique. Both qualitative assessment and estimated change in area based on height-times-width measurements of the barium column are accurate methods of estimating esophageal emptying.

Adolescent↗
PubMed1995

Mast cell cholangiopathy: another cause of sclerosing cholangitis.

A 75-year-old woman with known systemic mastocytosis presented with abdominal pain, ascites, and bile duct thickening on computed tomography and ultrasonography. A liver biopsy specimen showed infiltration with mast cells. Endoscopic retrograde cholangiography showed ductal changes compatible with those found in primary sclerosing cholangitis. Brush cytology of the intrahepatic bile ducts confirmed mast cell infiltration. Systemic mastocytosis can infiltrate the biliary system, producing a cholangiopathy radiographically similar to primary sclerosing cholangitis.

Aged↗
PubMed1995

Nodular sarcoidosis of the liver and spleen: analysis of 32 cases.

PURPOSE: To describe the computed tomographic (CT) appearance of nodular hepatosplenic sarcoidosis and its association with stage with chest radiography and clinical status. MATERIALS AND METHODS: Thirty-two patients (21 women, 11 men; aged 25-68 years) with nodular hepatosplenic sarcoidosis were evaluated. CT findings were described along with chest radiographic stage, clinical status, and level of angiotensin-converting enzyme (ACE). RESULTS: Nodules were small, multiple, and of low attenuation. Organomegaly was common. Abdominal adenopathy was present in 76% of the patients. Chest radiographs were normal in 25%; 61% had stage 1 or 2 radiographs. Abdominal or systemic symptoms were present in 66%. ACE level was elevated in 10 (91%) of 11 patients tested. No change in chest radiographic stage was noted in 74% of patients with follow-up radiographs. CONCLUSION: Nodular hepatosplenic sarcoidosis is associated with organomegaly, adenopathy, and symptoms. Nodules were not associated with advanced lung disease and did not herald a change in chest radiographic stage. An elevated ACE level may be helpful in diagnosis.

Adult↗
PubMed1995

Picture archiving communication systems in the intensive care unit.

The authors review the potential of picture archiving and communication systems (PACS) in the critical care environment. Presented and analyzed is a university hospital intensive care unit (ICU) PACS project. The objective of the project is to provide reliable, timely viewing of bedside radiographs in selected ICUs within the hospital. Key features include redundancy of critical hardware components and viewing stations that are simple to operate. The system was implemented in phases with incremental evaluation of performance and goals. PACS subsystems are discussed. On the basis of this experience, ICU PACS specifications and general considerations are presented. Also presented is a comparison of 10-year cost projections for conventional screen-film radiography and an ICU PACS that incorporates computed radiography. The costs of the two alternatives are comparable. PACS is a viable alternative to conventional screen-film imaging in the ICU setting and offers improved and more efficient patient care.

Alabama↗
PubMed1994

Flow cytometry: potential utility in monitoring drug effects in breast cancer.

Flow cytometric analysis of DNA ploidy and S-phase fraction are well recognized prognostic indicators in breast cancer. The present paper deals with the widening of the applications of flow cytometry to monitoring the effectiveness of antiestrogen therapy, detecting clonal selection and emergence of drug resistance, and monitoring chemosensitizing properties of drugs. Antiestrogen activity can be studied by DNA flow cytometry to address clinical research problems such as patient-specific pharmacokinetics, dosing compliance, and acquired antiestrogen resistance. Patient plasma specimens containing various concentrations of triphenylethylenes can be monitored for drug-induced effects using cell cycle measurements and correlated to in vivo drug levels. DNA flow cytometry has also been instrumental in the study of the effects of prolonged low-dose (0.5 microM for > 100 days) tamoxifen treatment on human estrogen receptor negative MDA-MB-231 cells, where it was shown that tamoxifen may significantly alter cell cycle kinetics and tumorigenicity of these cells, selecting a new, more aggressive, and rapidly growing clone. Lastly, it has been shown that the chemosensitizing properties of another triphenylethylene antiestrogen, toremifene, on estrogen receptor negative, multidrug resistant MDA-MB-231-A1 human breast cancer cells can be studied using flow cytometric analysis. Toremifene (and its metabolites N-desmethyltoremifene and toremifene IV) are able to "resensitize" MDA-MB-231-A1 cells to vinblastine and doxorubicin, as reflected in a marked shift of cells to G2/M phase of the cell cycle. Flow cytometry is a widely available technique that might be applied clinically to monitor, at the cellular level, drug effects on tumors, including the modulators of drug resistance.

Antineoplastic Agents↗
PubMed1994

Omeprazole versus H2-receptor antagonists in treating patients with peptic stricture and esophagitis.

BACKGROUND/AIMS: Although dysphagia in patients with peptic stricture is attributed to a decreased luminal diameter, coexistent esophagitis may be an equally important cause. The goals of this study were to determine whether medical healing of esophagitis in patients with stricture improves dysphagia and decreases dilatation need and to compare the efficacy and cost-effectiveness of omeprazole versus H2-receptor antagonists (H2RA). METHODS: Thirty-four dysphagic patients with peptic stricture and erosive esophagitis were dilated and randomized to omeprazole 20 mg every day versus H2RA (ranitidine 150 mg twice daily or famotidine 20 mg twice daily). Patients received further dilatations only if dysphagia frequency was greater than or equal to once per week. At 3 and 6 months, patients were assessed for esophagitis healing, dysphagia relief, and bougienage requirements. Cost-effectiveness of omeprazole and H2RA was determined. RESULTS: Patients with healed esophagitis at 3 and 6 months were more likely to dysphagia-free and to require fewer dilatations than patients with persistent esophagitis. At 6 months, omeprazole produced a significantly (P < 0.01) higher rate of esophagitis healing, dysphagia relief, and fewer dilatations compared with H2RA. Omeprazole was also 40%-50% more cost-effective. CONCLUSIONS: Esophagitis healing improves dysphagia and decreases dilatation need in patients with peptic stricture. Omeprazole heals esophagitis and relieves dysphagia more efficaciously than H2RA while decreasing costs to patients.

Aged↗
PubMed1994

Detection of gastroesophageal reflux: value of barium studies compared with 24-hr pH monitoring.

OBJECTIVE: Monitoring of esophageal pH is widely held to be the most sensitive test for gastroesophageal reflux, but it is expensive and is not available in all centers. Controversy surrounds the role of barium studies in the detection of reflux despite years of experience with their use. We studied the efficacy of fluoroscopic detection of spontaneous and provoked gastroesophageal reflux compared with 24-hr monitoring of esophageal pH. SUBJECTS AND METHODS: In 117 subjects with clinical findings suggestive of gastroesophageal reflux, we recorded fluoroscopic observations of spontaneous reflux and of reflux elicited by coughing, the Valsalva maneuver, rolling from supine to the right lateral position, and the water-siphon test. Subjects were considered to have reflux if 24-hr monitoring of esophageal pH within 14 days of the barium examination showed esophageal pH to be less than 4 for intervals exceeding the 95th percentile values previously reported for a control group. RESULTS: Barium studies showed unprovoked, spontaneous reflux in 26% of subjects proved by pH measurements to have gastroesophageal reflux. When the water-siphon test was used, the sensitivity of fluoroscopic detection rose to 70%, with a specificity of 74% and positive predictive value of 80%. Clinically significant reflux was detected radiographically in five patients in whom it was not detected by pH monitoring. CONCLUSION: These data are contrary to prior reports and indicate that barium studies are useful for screening patients with clinical findings suggestive of gastroesophageal reflux. The sensitivity of barium studies is highest when maneuvers are used to elicit reflux.

Adolescent↗
PubMed1994

Treatment of achalasia: the best of both worlds.

OBJECTIVE: To conduct a retrospective analysis of one center's experience with treating achalasia over 4 yr with skilled gastroenterologists using primarily the Rigiflex balloon dilator and with a senior surgeon performing Heller myotomies. METHODS: Newly diagnosed cases of achalasia were identified by a computer search of hospital records. Charts were reviewed for the presence/severity of dysphagia, regurgitation, heartburn, and chest pain. Weight loss was also recorded. Esophageal manometries and barium swallows were reviewed. Choice of treatment was made freely by patients. With an a priori definition of success, follow-up was conducted by telephone interviews. RESULTS: A total of 45 achalasia patients (mean age, 46 yr; 32 females, 13 males) were identified with a symptoms-frequency as follows: dysphagia, 100%; regurgitation, 78%; heartburn, 50%; and chest pain, 42%. Mean weight loss was 17.5 pounds. Primary treatment was pneumatic dilation in 36 patients and surgery in nine patients. In a total of 45 pneumatic dilations, three (6.6%) were complicated by perforation. Five (14%) patients required repeat dilation. Mean duration of follow-up for pneumatic dilation and surgery was 27 months and 20.8 months, respectively. The overall excellent-good success rates were: pneumatic dilation 88% and surgery 89%. In comparing the efficacy of pneumatic dilation versus surgery, all symptoms were improved significantly (p < 0.01) in both groups, except heartburn, which increased postmyotomy. CONCLUSIONS: If both procedures are available by skilled operators, pneumatic dilation and surgery are equally effective in the treatment of achalasia.

Adolescent↗
PubMed1993

A breast cancer clone selected by tamoxifen has increased growth rate and reduced sensitivity to doxorubicin.

The in vivo growth rate and the chemosensitivity patterns of a cell clone selected by tamoxifen from the estrogen receptor-negative human breast cancer cell line MDA-MB-231 was studied in the nude mouse model and with flow cytometry. To investigate the growth rate of the wild-type and clone cells in vivo, the cells were inoculated into the opposite flanks of 5 male nude mice. Drug sensitivity to doxorubicin (10 ng/mL), vinblastine (1 ng/mL), and paclitaxel (1 ng/mL) was examined in wild-type/clone cell mixture using flow cytometry. Northern blot technique was used to study the expression of mdr-1 messenger RNA in both the wild-type and the clone cells. The tumors derived from the clone and wild-type cells were, following a 3-week growth period, 260.2 +/- 78.8 mm2 vs. 68.3 +/- 50.8 mm2 in size, respectively (P < 0.001). Following a 28-day continuous exposure, doxorubicin was selectively, toxic to the wild-type cells, while having no apparent effect on the clone population. However, paclitaxel- and vinblastine-treated wild-type/clone cell mixtures did not exhibit a differential cytotoxic effect on either cell population. It was concluded that the clone selected by tamoxifen shows an aggressive growth rate in vivo and an altered chemosensitivity pattern to doxorubicin in vitro.

Animals↗
PubMed1990

Computer facilitation of the resident selection process.

A personal computer software system has been designed and implemented to facilitate the numerous complex tasks involved in the resident selection process. The computer tracks the status of each candidate, monitors each application for incomplete documentation, generates personalized correspondence, computes and maintains a scoring system based on evaluation by each Resident Selection Committee member, and provides various data printouts (eg, list of candidates by medical school; persons granted an interview; and ranking lists). Developed with the intent to share with the academic community, the system improves organization and accuracy, and notably decreases time spent by administrative assistants and staff members in the resident selection process.

Computer Systems↗
PubMed1988

Preoperative evaluation of abdominal aortic aneurysm by MR imaging with aortography correlation.

Sonography, computed tomography, and most recently, magnetic resonance imaging (MRI) have been advocated as noninvasive imaging methods for the preoperative evaluation of patients with abdominal aortic aneurysms (AAA). We prospectively assessed the value of MRI in this clinical setting. Twenty of 23 patients with AAA referred for evaluation with biplane aortography underwent MRI within 3 days of aortography. MR and angiographic studies were interpreted prospectively and independently and then the results were compared with each other and with the operative findings. All angiographically demonstrated infrarenal and suprarenal aneurysms except one were documented as such by MRI. The distal extent of the aneurysm on MRI agreed with that on angiography in all but 3 cases. MRI is an accurate method for assessing the size and extent of AAA and its relationship to the main renal artery origins. MRI is not accurate in detecting vascular obstructions or accessory renal arteries. Therefore, the usefulness of MRI and the need for aortography in preoperative assessment of AAA depends upon the specific information the surgeon requires prior to aneurysmectomy in a given patient.

Aorta, Abdominal↗
PubMed1987

Malignant hemangiopericytoma: computed tomography and magnetic resonance imaging.

Computed tomography and magnetic resonance imaging of a malignant hemangiopericytoma in a 58-year-old woman are described. The tumor was initially found in the abdomen and resected 34 years ago, but recurred 18 years later, followed by repeated recurrence and eventually metastasis to the lung and then to the liver. The lung nodules were round or oval, homogeneous, and well circumscribed while the massive tumor in the right lobe of the liver was poorly delineated with irregular areas of cystic necrosis. With proper setting of the repetition time and echo delay, the metastatic tumor became distinct from the uninvolved hepatic tissue on magnetic resonance imaging. In this case computed tomography and magnetic resonance imaging were complementary in evaluation of such a tumor.

Abdominal Neoplasms↗
PubMed1987

The case for radioprotective eyewear/facewear. Practical implications and suggestions.

Numerous eyeglass lens materials have been recommended for protection of radiologists' eyes from the cataractogenic effect of radiation during fluoroscopic procedures. For the most part, these lenses coincidentally attenuate x-ray beams because they contain elements of high atomic number that are added to increase refractive index. With a bean hardened to simulate scatter, direct transmission ratios were measured for 32 commercially available lens materials. Scatter to the eye, both through and around the glass lenses and secondary scatter to the eye from the radiologist's head, was determined with lenses mounted on a head phantom and a 1-cm3 ion chamber in the position of the eye. Transmission ratios for the various lenses ranged from 3% to 98% for an 80 kVp x-ray beam (HVL = 4.5 mm Al). Measurements with the head phantom in place show that secondarily scattered radiation from the fluoroscopist's head contributes significantly to ocular exposure. Optimal radiation protection of the eyes during fluoroscopy depends not only on eyeglasses with leaded glass, but also on shielding of sufficient size and shape to reduce exposure to the surrounding head.

Cataract↗