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W J Shih

Publications and source records attributed to W J Shih.

At least 19 recordsLinked to original sources
PubMed1999

Detection of abscesses with Tc-99m HMPAO leukocyte scintigraphy depends on their stage and location.

Two abscesses were shown on CT in a 72-year-old man: one in the left hip and one in the left pelvic region that resulted from a motor vehicle collision that occurred 8 months earlier. Bone scintigraphy showed increased uptake in the left hip area. On Tc-99m HMPAO leukocyte imaging, the hip area appeared to be photopenic, and the abscess of the left pelvis was not identified. Incidental uptake in the left lung base appeared to be an active acute inflammatory process as evidenced by an infiltrating lesion in the left lower lung on a chest radiograph. Because leukocyte scintigraphy cannot detect the presence of a chronic inflammatory process in the absence of acute inflammatory cells, the patient's abscesses in the left hip and the left pelvis did not localize Tc-99m HMPAO-labeled neutrophils. The cold lesion in the left hip area was most likely caused by the lesion in the reticuloendothelial system (bone marrow); the unidentifiable pelvic lesion was related to the area(s) outside the reticuloendothelial system. In interpreting a labeled leukocyte image, clinicians should be alert to the stage (chronic or acute) and location (regardless of whether in the reticuloendothelial system) of infectious lesion(s). In this patient, a wide spectrum of manifestations was evident on leukocyte scintigraphy.

Abscess↗
PubMed1998

Modifying the design of ongoing trials without unblinding.

Conventional group sequential designs provide an objective basis for reducing the sample size of a trial if the difference between the treatments is much more or much less than anticipated. The flexibility of group sequential designs can be enhanced by allowing the sample size to increase when the variability turns out greater than expected. This can be accomplished by examining the variability before unblinding the data at the first stage of the trial. Depending on the result of this examination, the trial may continue as planned, or the design may change in various ways, for example, by increasing the sample size or by changing the number of stages or the scheduling of the interim analyses. The effect of this adaptive flexibility on the error rates turns out as one would expect from the findings for fixed-sample designs: no material impact on the type I error rate and an effect on the power that depends on the final total sample size.

Clinical Trials as Topic↗
PubMed1998

Functional retention of Tc-99m MIBI in mediastinal lymphomas as a predictor of chemotherapeutic response demonstrated by consecutive thoracic SPECT imaging.

Tc-99m MIBI is used as a tumor imaging agent and has been proposed to measure p-glycoprotein function, which plays an important role in tumor multidrug resistance to chemotherapy. It has been reported that lung cancer and breast cancer with a high retention of Tc-99m MIBI have been more responsive to chemotherapy than tumors with low retention. Thus Tc-99m MIBI SPECT could be used as a measure of p glycoprotein function and consequently may serve as a predictor of the tumor's responsiveness to chemotherapeutic agents. Described here are two patients with lymphomas, one with non-Hodgkin's lymphoma and the other with Hodgkin's disease, who underwent Tc-99m MIBI thoracic SPECT before and after chemotherapy. The sequential studies demonstrated a reduction in tumor size and diminished tumor uptake in one patient and disappearance of tumor uptake after a course of chemotherapy in the other patient. The data suggest that elevated Tc-99m MIBI uptake in a tumor as a result of retention by p glycoprotein not only demonstrates mediastinal involvement of lymphomas but also may be used to forecast responsiveness to chemotherapy.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

Tc-99m MIBI thoracic SPECT for the detection of intrathoracic tumor masses.

Thirty-one men (age range, 46-76 years; mean age, 64.8 years) with intrathoracic masses suggesting possible malignancy on the basis of chest radiography or CT underwent preoperative Tc-99m MIBI SPECT examinations. Diagnosis was confirmed on pathologic examinations of samples obtained either at thoracotomy, esophagectomy, or by biopsy. Twenty-five patients had primary lung cancer, including squamous cell carcinoma, large cell carcinoma, adenocarcinoma, and small cell carcinoma. Two patients had lymphomas with spread to the mediastinum, and three patients had extrathoracic primary cancers (one squamous cell carcinoma of esophagus, one squamous cell carcinoma originating from a head and neck tumor, and one metastatic mediastinal leiomyosarcoma). One patient with a tuberculoma had negative results of the Tc-99m MIBI examination. Tc-99m MIBI had a 86.7% sensitivity rate, a 0% false-positive rate, and a 100% positive predictive value to detect malignant intrathoracic masses. There was a 13% false-negative rate, however, suggesting that MIBI-SPECT may underdiagnose malignant lesions. SPECT findings of these 31 patients can be classified as 1) mass with increased uptake, n = 23; 2) ring-like appearance of increased uptake, n = 3; 3) mass with absent uptake, n = 4; and 4) photon-deficient mass, n = 1. Absent uptake in patients with mass lesions could be explained by necrosis of the lesion (caseation necrosis or massive tumor necrosis with or without bleeding). Most malignant intrathoracic masses are Tc-99m MIBI avid and may be detected with a high degree of sensitivity and with an excellent positive predictive value. A positive MIBI scan may help in the clinical diagnosis of malignancy. The use of Tc-99m MIBI could serve not only as a tumor imaging agent, but also may be used to determine the extent of spread and potentially the chemotherapeutic responsiveness of a tumor.

Aged↗
PubMed1998

An unusual case of a tibial metastasis as the clinical presentation of bronchogenic adenocarcinoma.

A patient with initial complaints of leg pain and difficulty walking was found to have a large right tibial metastatic tumor and poorly differentiated adenocarcinoma of the lung. Findings from total-body bone scintigraphy include a large area of increased uptake in the proximal half of the right tibia with a photon-deficient area medially, and focal areas of uptake in a right rib, in the femoral neck and the left ileum. An irregular area of increased uptake in the left lung mass was shown by thoracic bone SPECT. This is an unusual case of a tibial metastasis as the first clinical presentation of bronchogenic adenocarcinoma.

Adenocarcinoma↗
PubMed1998

Stratified testing for treatment effects with missing data.

Dawson and Lagakos (1993, Biometrics 49,1022-1032) proposed a stratified test for repeated measures data that contain missing observations. They recommended stratification based on missing data patterns and considered sufficient conditions under which the size of the test is properly retained. In this paper, we point out some practical problems with these conditions and illustrate them with their CD4 count example as well as a stimulation study. We give a less stringent condition and delineate its merit. We also discuss what to do when none of the conditions are met.

Biometry↗
PubMed1997

Design for sample size re-estimation with interim data for double-blind clinical trials with binary outcomes.

Estimation of sample size in clinical trials requires knowledge of parameters that involve the treatment effect and variability, which are usually uncertain to medical researchers. The recent release within the European Union of a Note for Guidance from the Commission for Proprietary Medical Products (CPMP) highlights the importance of this issue. Most previous papers considered the case of continuous response variables that assume a normal distribution; some regarded the portion up to the interim stage as an 'internal pilot study' and required unblinding. In this paper, our concern is with the case of binary response variables, which is more difficult than the normal case since the mean and variance are not distinct parameters. We offer a design with a simple stratification strategy that enables us to verify and update the assumption of the response rates given initially in the protocol. The design provides a method to re-estimate the sample size based on interim data while preserving the trial's blinding. An illustrative numerical example and simulation results show slight effect on the type I error rate and the decision making characteristics on sample size adjustment.

Clinical Trials as Topic↗
PubMed1997

Testing for treatment differences with dropouts present in clinical trials--a composite approach.

A major problem in the analysis of clinical trials is missing data from patients who drop out of the study before the predetermined schedule. In this paper we consider the situation where the outcome measure is a continuous variable and the final outcome at the end of the study is the main interest. We argue that the hypothetical complete-data marginal mean averaged over the dropout patterns is not as relevant clinically as the conditional mean of the completers together with the probability of completion or dropping out of the trial. We first take the pattern-mixture modelling approach to factoring the likelihood function, then direct the analysis to the multiple testings of a composite of hypotheses that involves the probability of dropouts and the conditional mean of the completers. We review three types of closed step-down multiple-testing procedures for this application. Data from several clinical trials are used to illustrate the proposed approach.

Bias↗
PubMed1997

Multiple imagings to diagnose the chondrosseous metaplasia within a lipoma near the knee.

A 61-year-old man with a slow-growing, painless mass in the area of the right knee underwent radiographic, computed tomographic (CT), arthrographic, arteriographic, and bone scintigraphic imaging studies. Scintigraphy showed an area of intense uptake in the anterolateral part of the knee; the uptake of the knee was much higher than that of the knee joints, but the area was not connected to the joint. Radiographic findings suggested an osteocartilaginous mass which was seen to contain low-density fatty tissue on the CT exam. Arthrography revealed that there was no connection of the mass to the knee joint. Arteriography showed a mildly vascularized tumor mass. Upon removal, the mass was well encapsulated, measuring 10 x 7 x 7 cm, and consisted of integrated nodules of bone, cartilage, and fat tissue. Microscopic examination confirmed lipoma with osteochondromatous metaplasia. The intense uptake in the lipoma near the bone or joint on the bone scan and multiple osteochondromatous nodules shown on CT may serve as characteristic features of the rare chondrosseous metaplasia within a lipoma.

Arthrography↗
PubMed1997

Kawasaki disease evaluated by two-dimensional echocardiogram and dipyridamole 201Tl-chloride myocardial SPET.

Kawasaki disease (mucocutaneous lymph node syndrome) is a disease of unknown aetiology that affects infants and children, with most patients having myocardial involvement. To evaluate the incidence and nature of myocardial involvement, 30 patients with Kawasaki disease underwent both dipyridamole 201Tl-chloride myocardial single photon emission tomography (SPET) and two-dimensional echocardiography (2D-Echo), which were performed within 7 days of each other. The SPET image of 15 of 30 (50%) patients showed 27 segments with myocardial perfusion abnormalities: 6 patients had one or more segments showing redistribution; 6 patients had both one or more segments of reverse redistribution and redistribution; 2 patients had reverse redistribution; and one patient had one redistribution and one fixed defect. Eight of 15 (53.3%) SPET abnormalities included reverse redistribution. Of 15 patients with positive SPET, 13 were male (age 0.3-12 years, mean = 3.55) and 2 were female (age 3-4 years, mean = 3.5). The interval between the onset of disease and SPET ranged from 1 to 594 weeks. Of the 15 patients with a negative SPET, 10 were male (age 0.4-6 years, mean = 2.08) and 5 were female (age 0.2-5 years, mean = 1.8). The interval between the onset of the disease and SPET ranged from 2 to 54 weeks. There were no significant differences in age (P = 0.10), sex (P = 0.41) or interval between the onset of disease and SPET in the patients with positive SPET and those with negative SPET (P = 0.60). With 2D-Echo, 16 (11/15 patients with positive SPET and 5/15 patients with negative SPET) of 30 (53.3%) patients had demonstrable coronary aneurysms. There was no statistical difference (P = 0.4) in the ability to detect myocardial abnormalities between SPET and 2D-Echo. Combining SPET and 2D-Echo, detectability of myocardial involvement was 66.6% (20/30). We conclude (1) that more than 50% of the patients' myocardial involvement was expressed by the myocardial perfusion status on SPET or by coronary aneurysm on 2D-Echo. Combined SPET and 2D-Echo may be of additive benefit for the detection of myocardial involvement. All 15 patients with SPET abnormalities had one or more segments of redistribution and/or reverse redistribution, indicating myocardial ischaemia and/or damaged but viable myocardium.

Child↗
PubMed1997

A normal technetium-99m-DTPA renogram in renal cell carcinoma: a case report.

A 64-yr-old man with a renal mass had a preoperative 99mTc-DTPA renal flow study and renogram. An area of minimally relative increase in flow in the upper half of the right kidney was thought to reflect the high vascularity of the renal mass. A subsequent renogram showed no mass defect in the area of relatively high flow of the right kidney. The patient had a right nephrectomy. The removed kidney showed an extrarenal mass measuring 6 x 5.5 x 5 cm at the upper pole of the kidney. The mass was confirmed to be a renal cell carcinoma, clear cell type. There was no renal tissue invasion. These finding suggest an extrarenal mass pattern may be difficult to identify with a normal appearing renogram.

Carcinoma, Renal Cell↗