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Biomedical subjects

K P Wang

Publications and source records attributed to K P Wang.

At least 19 recordsLinked to original sources
PubMed2000

MR imaging of mediastinal lymph nodes: evaluation using a superparamagnetic contrast agent.

The purpose of this study was to determine whether intravenous injection of a magnetic resonance (MR) contrast agent, ultrasmall superparamagnetic iron oxide (ferumoxtran-10), can be useful in characterizing lymph nodes in patients with lung cancer. Twelve patients with known or suspected lung cancer were studied. Pre- and postcontrast injection of ferumoxtran-10 MR scans of the chest were obtained. Analysis of the signal intensities and bronchoscopic fine needle aspiration of a single node were performed in each patient. Six of 12 patients had a final diagnosis of lung cancer. T1-weighted images were best for localizing mediastinal lymph nodes. Signal intensity changes before and after contrast were best visualized on T2-weighted and gradient-echo images. All four patients with lung cancer who had nodes positive for malignancy at biopsy had no change in signal intensity of the nodes on T2 images. The signal intensity decreased in the remaining two patients, and the nodes were benign. Of the eight patients with benign disease, five had no change in signal intensity of the nodes. Therefore the sensitivity for tumor involvement of the nodes is 100%, but the specificity is only 37.5%. Ferumoxtran-10 is a contrast agent that can alter the signal intensity of lymph nodes. Lack of signal change may be due to malignant or inflammatory change. Studies in a larger population of lung cancer patients may help to characterize the utility of this agent further. J. Magn. Reson. Imaging 2000;12:899-904.

Aged↗
PubMed2000

Three-dimensional CT-guided bronchoscopy with a real-time electromagnetic position sensor: a comparison of two image registration methods.

STUDY OBJECTIVES: To compare two different image registration methods for accurately displaying the position of a flexible bronchoscope on a previously acquired three-dimensional CT scan during bronchoscopy. SETTING: Bronchoscopy suite of a university hospital. PATIENTS: Fifteen adult patients scheduled for nonemergent bronchoscopy. METHODS: A miniature electromagnetic position sensor was placed at the tip of a flexible bronchoscope. Previously acquired three-dimensional CT scans were registered with the patient in the bronchoscopy suite. Registration method 1 used multiple skin fiducial markers. Registration method 2 used the inner surface of the trachea itself for registration. Method 1 was objectively assessed by measuring the error distance between the real skin marker position and the computer display position. Methods 1 and 2 were subjectively assessed by the bronchoscopist correlating visual bronchoscopic anatomic location with the computer display position on the CT image. RESULTS: The error distance (+/- SD) from known points for registration method 1 was 5.6 +/- 2.7 mm. Objective error distances were not measured for method 2 because no accurate placement of the bronchoscope sensor could be correlated with CT position. Subjectively, method 2 was judged more accurate than method 1 when compared with the fiberoptic view of the airways through the bronchoscope. Additionally, method 2 had the advantage of not requiring placement of fiducial markers before the CT scan. Respiratory motion contributed an error of 3.6 +/- 2.6 mm, which was partially compensated for by a second tracking sensor placed on the patient's chest. CONCLUSION: Image registration method 2 of surface fitting the trachea rather than method 1 of fiducial markers was subjectively judged to be superior for registering the position of a flexible bronchoscope during bronchoscopy. Method 2 was also more practical inasmuch as no special CT scanning technique was required before bronchoscopy.

Biopsy↗
PubMed1999

Endobronchial laser therapy.

We have sought to briefly outline the history and current role of laser therapy in airway obstruction. A primary goal in the use of laser therapy is the safe, effective, and rapid palliation of symptoms owing to tracheal or bronchial obstruction. This seems clearly supported in the literature despite some variation in definitions as to measurement of success. Objective criteria for improvement has also been studied, with authors noting improvement in walk tests, spirometric studies, and caliber of airways after treatment in significant percentages of patients. Patient survival, as noted by Ramser and Beamis, may not be the proper endpoint when discussing therapy, which for malignant causes, is meant to be palliative. Noting this, there are many benign conditions that may be effectively treated with laser therapy with a possible "cure" for some lesions defined as "carcinoma in situ." We believe laser therapy in the treatment of airway obstruction is an important tool that has proven beneficial in the therapy of benign and malignant lesions of the airway. Although future studies should prospectively examine survival characteristics, the current evidence firmly supports the use of laser as a useful modality of therapy in our endeavors to provide palliative and potentially curative care to our patients with lung disease.

Airway Obstruction↗
PubMed1996

The staging of lung cancer by bronchoscopic transbronchial needle aspiration.

The development of flexible transbronchial needles for hilar and mediastinal aspiration had made possible noninvasive staging at the time of the initial diagnostic bronchoscopic examination. Combining the specificity of TBNA with the sensitivity of thoracic CT scanning greatly enhances the utility of this procedure. A bronchoscopically oriented staging system that utilizes the complementary advantages of both of these techniques is outlined. The staging of bronchogenic carcinoma by TBNA is a safe and cost-effective technique that can be routinely utilized to stage lung cancer. Ultimately, its value will depend upon whether the initial encouraging reports of its use can be reproduced by bronchoscopists in practice.

Biopsy, Needle↗
PubMed1995

Transbronchial needle aspiration and percutaneous needle aspiration for staging and diagnosis of lung cancer.

In summary, knowledge of the exact location of lymph nodes in mediastinum and hilar areas and their relationship to the puncture site of TBNA is the first step to a successful TBNA. The necessity to determine the N3 status and multistation status of patients with bronchogenic carcinoma being evaluated for surgery and the current financial restraint of the medical care system further highlight the potential of this simple, effective, and safe procedure. TBNA can markedly enhance the diagnostic yield of flexible bronchoscopy. TBNA and PCNA are complimentary procedures.

Biopsy, Needle↗
PubMed1994

Transbronchial needle aspiration for cytology specimens.

Transbronchial needle aspiration (TBNA) for diagnosis and staging of bronchogenic carcinoma has evolved in the USA since the late 1970's. Initial reports advised that aspirated specimens be flushed into a container by normal saline or Hank's solution and processed in a cytology laboratory usually by Millipore filter and other techniques. A highly sophisticated cytology laboratory is the key to the success of this procedure. This study was designed to assess a simpler alternative method of processing the specimen by a direct smear technique. From June 1990 to September 1990, 40 procedures were performed on 34 consecutive patients. Seventy two paired direct smear and fluid specimens for cytology examination were collected. Fifty specimens were found to be negative in both types of specimen preparation. Fifteen were found to be positive in both types of specimens preparation, and six specimens were found to be positive only in the direct smear preparation. One of the 72 specimens was found to be positive in the Millipore and other preparation techniques. Based on our data, we conclude that the use of the direct smear for TBNA specimen preparation is an effective, simpler, and improved method. Proper use of it may increase the diagnostic yield and result in better acceptance of this new procedure.

Biopsy, Needle↗
PubMed1993

NdYAG laser closure of a bronchopleural fistula.

We report the successful closure of a small bronchopleural fistula, which developed following right lower lobe lobectomy for squamous cell carcinoma. The patient underwent fibreoptic bronchoscopy diagnosis of possible bronchopleural fistula, manifested by cough and hydropneumothorax, following right lower lobe lobectomy. A small fistula was found at the stump of the right lower lobe. A chest tube with suction was placed for drainage before the therapeutic fibreoptic bronchoscopy. Through the flexible bronchoscope, using the tip of the bare laser fibre, a superficial erosion and bleeding around the fistula was created and coagulated by using a defocused yttrium aluminium garnet (Yag) laser beam. Close follow-up of the patient showed air leakage had stopped completely in 48 h. The chest tube was removed and the fistula never recurred. We suggest that this procedure may be used in selective patients with a small bronchopleural fistula. If successful, it can reduce the morbidity of more invasive surgical procedures.

Adult↗
PubMed1992

[A comparative study of coronary arteriography and myocardial emission computed tomography in the diagnosis of coronary heart disease].

Both coronary arteriography (CAG) and myocardial emission computed tomography (ECT) were performed in 58 patients. According to CAG findings and clinical manifestations, 47 patients were diagnosed as coronary heart disease (CHD), while 11 not. CAG was abnormal in 39 patients of the 47. The sensitivity and specificity of CAG were 83% and 100% respectively. The diagnosis of CHD was made without any doubt in patients with abnormal CAG. The sensitivity of ECT was 97.9%, the specificity only 45.5%, and the predictive value of negative ECT 83.3%. Therefore, abnormal ECT should be closely related to the clinical manifestations in order to evaluate its significance and a normal ECT may rule out CHD with more reliability.

Adult↗
PubMed1991

Needle brush in the diagnosis of lung mass or nodule through flexible bronchoscopy.

Transbronchial needle aspiration (TBNA), in comparison with cytology brush and forceps biopsy, in the diagnosis of a pulmonary mass or coin lesions has been studied by Shure and Wang in the past. Both studies concluded that TBNA markedly increased the diagnostic yield. A new instrument, a "needle brush" (Mill Rose Lab), has been developed and compared with the following three instruments: a regular cytology brush was used first, followed by needle brush, TBNA, and forceps biopsy under fluoroscopy. Twenty-four patients were studied. A specific diagnosis was made in 16 patients (15 malignancies; one granuloma); in three patients, results were suspicious for malignancy, three patients had negative results, and in two patients the study was not complete. "Needle brush" biopsy was positive in 11 patients (exclusively in four); TBNA was positive in eight (exclusively in two). Regular brush biopsy was positive in seven (exclusively in none). Forceps biopsy was positive in four (exclusively in one; granuloma). We conclude that the needle brush and TBNA have a higher diagnostic yield in malignant lung masses or nodules. The use of regular brush and forceps biopsy did not increase the diagnostic yield in malignancy. Forceps biopsy might be more useful in benign diseases.

Biopsy, Needle↗
PubMed1991

Vernal keratoconjunctivitis with shield ulcer--a case report.

This 9-year-old boy had a three-year history of vernal keratoconjunctivitis. A shield ulcer developed in the superior part of the cornea. The shield ulcer is a rare manifestation of the disease. Although the cause of shield ulcer is unknown, the association of shield ulcer with large papillae suggests a mechanical cause. The symptoms of itching and mucous discharge were relieved after medications with topical steroid and cromolyn sodium, but the large shield ulcer was persistent. The vernal ulcer was treated with a 72 hours collagen shield. The ulcer healed rapidly within 5 days, leaving a corneal opacity about the level of Bowman's layer.

Child↗
PubMed1989

Flexible transbronchial needle aspiration for the diagnosis of sarcoidosis.

To determine the value of transbronchial needle aspiration biopsy in the diagnosis of sarcoidosis, we reviewed a 1-year experience of consecutive patients with sarcoidosis presenting with hilar and/or paratracheal adenopathy. The sensitivity of transbronchial needle aspiration biopsy in obtaining specimens of noncaseating granulomas was 90%. This yield exceeds that of most published reports of transbronchial lung biopsy and bronchial mucosal biopsy and suggests that transbronchial needle aspiration biopsy may be a valuable diagnostic tool in the evaluation of these forms of sarcoidosis.

Biopsy, Needle↗
PubMed1989

[Electrophysiologic studies on reentrant ventricular arrhythmia in the late myocardial infarction period].

The mechanisms of reentrant ventricular tachycardia were studied in canine post-infarction model. In 15 dogs that weighed 10-20 kg, the anterior descending coronary artery was ligated. 3 to 7 days after coronary artery occlusion, the dogs were reoperated to set up a composite electrode or a patch electrode with 32 bipolar electrodes. The composite electrode was utilized to record ventricular late potentials (VLPs) from the epicardial surface of the infarction zone (IZ) and adjacent normal zone (NZ). The bipolar electrodes were used to record the epicardial isochronal maps. 16 bipolar electrodes were placed over the area of infarction and its bordering zone and the other 16 bipolar electrodes were distributed over the remaining surface of the ventricle. Reentrant ventricular tachycardias were induced by programmed electrical stimulation. The VLPs and epicardial isochronal activation were recorded by SC-16 oscillograph and computerized mapping system during sinus rhythm and programmed stimulation. The experiments showed; 1) VLPs were demonstrated in 11 of the 15 dogs (73.3%) during programmed stimulation. 2) The reentrant circuit has a characteristic figure-8 configuration in the form of two circulating wave-fronts around arcs of functional conduction block that coalesce into a slow commun reentrant wave-front. One of the two synchronous circuits traveled clockwise and the other counter-clockwise. 3) VLPs represent a delayed depolarization at the ischemic myocardium, where the impulse conducts slowly in the reentrant circuit. It is clear that the present study may increase the understanding of the mechanism of ventricular arrhythmias in the late myocardial infarction period.

Animals↗