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W J Shih

Publications and source records attributed to W J Shih.

At least 55 records · Page 3Linked to original sources
PubMed1999

Planning and analysis of repeated measures at key time-points in clinical trials sponsored by pharmaceutical companies.

In this paper we explore the possible reasons why medical papers reporting clinical trials sponsored by the pharmaceutical industry often analyse repeated measures data at certain key time-points instead of employing sophisticated models of repeated measures proposed by many statisticians. A survey indicated that the priority reason in the industry for having repeated measures in clinical trials is to monitor the trial and to utilize the early results for strategic decision making. We discuss what the common statistical methods do and do not offer for analysis of repeated measures in such clinical trials. We advocate the need to improve the understanding of the medical interest in conducting longitudinal trials in the industry, and to plan and analyse the repeated measures accordingly. We address the medical interest by formulating the problem and give illustrative examples for both phases II and III trials.

Alendronate↗
PubMed1999

Testicular lymphoma with bone/bone marrow metastases illustrated by scrotal sonography, spinal MRI, and total body Tc-99m HMDP and Tc-99m MIBI images.

An 83-year-old man with testicular lymphoma demonstrated progressive scrotal enlargement with non-homogeneity sonographically and abnormally increased uptake in the scrotum of Tc-99m HMDP and Tc-99m MIBI scintigraphically. Extensive bone/bone marrow metastases were exhibited by Tc-99m MIBI and Tc-99m HMDP scintigraphies and MRI of the spine. In addition, focal/tubular activity of the femoral bone marrow on Tc-99m MIBI imaging was consistent with skeletal scintigraphic findings. It is emphasized that Tc-99m MIBI total body imaging enabled the demonstration of testicular lymphoma as increased uptake and the illustration of skeletal/bone marrow metastases as diffuse and/or focal increased uptake, especially focal/tubular MIBI activity of the femoral marrow.

Aged↗
PubMed1999

Axillary lymph node uptake of Tc-99m MIBI resulting from extravasation should not be misinterpreted as metastasis.

Ipsilateral axillary lymph node visualization due to extravasation of Tc-99m MDP intravenous injection has been well documented. A patient with suspected angina underwent Tc-99m MIBI myocardial SPECT who had extravasation of Tc-99m MIBI in the antecubital region resulting in ipsilateral axillary lymph node uptake. This finding should not be misinterpreted as lymphatic nodal metastasis in a patient with breast cancer or lung cancer.

Angina Pectoris↗
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↗
PubMed1999

Normal variants of a photon-deficient area in the lower sternum demonstrated by bone SPECT.

PURPOSE: A highly variable normal appearance of the sternal area makes interpretation difficult on planar bone imaging. These normal variants occur especially in the area above the xiphoid process of the sternum in which an oval photopenic area on anterior planar images may be seen. This finding is most likely caused by localized incomplete fusion. METHODS: Of a group of 188 patients, 35 patients (33 men, 2 women; age range, 30 to 85 years; mean age, 57 years) were examined with sternal SPECT and planar bone imaging. These patients, who had no history of sternal trauma, surgery, radiation, or infection, were referred for bone scan for metastatic work-up (n = 20), back pain (n = 6), and other conditions (n = 9). Thus 11 of 35 (31%) patients had a SPECT study that showed a photopenic area in the lower sternum. RESULTS: The incidence of this normal variant was higher than the 2% to 7.7% previously reported, indicating improved detection by SPECT. The normal variant appears to be less apparent on planar bone images and is seen more clearly on SPECT images. CONCLUSION: Differentiation from malignancy appears to be related to lesion symmetry, location, midline, and evenly distributed radioactivity surrounding the edge of the photopenic area.

Adult↗
PubMed1999

Bone agent localization in hepatic metastases.

We present the bone scintigrams of two patients, which demonstrate diffuse extraosseous uptake of a bone agent in metastatic masses in the liver, one from a primary lung tumor and one from a primary breast tumor. The bone imaging agent did not localize in the brain metastases in these patients. CTs of the abdomen in both patients showed massive metastases in the liver with multiple areas of tumor necrosis. The CT of the abdomen of the breast cancer patient showed multiple small hepatic calcifications. Autopsy revealed massive tumor necrosis with calcifications in the enlarged liver. In routine bone scintigraphy, diffuse uptake of bone agents in the liver of a patient with a known malignancy should be considered suggestive of massive hepatic metastases.

Adenocarcinoma↗
PubMed1999

Localization of a bone imaging agent in a calcified hematoma.

A patient with chronic renal failure and secondary hyperparathyroidism had iliac bone biopsy. The procedure was complicated by a soft-tissue hematoma, which had calcified. A 3-4-cm palpable mass was visible in the lower left abdominal wall. Intense uptake of 99mTc-HMDP corresponded with the location of the calcified hematoma in this patient.

Adult↗
PubMed1999

Myositis ossificans demonstrated by positive gallium-67 and technetium-99m-HMDP bone imaging but negative technetium-99m-MIBI imaging.

Gallium-67-citrate and 99mTc-diphosphate bone imaging agents are localized in myositis ossificans, a tumor-like benign soft-tissue mass that makes it impossible to differentiate between malignant tumor and the infection/inflammatory process. We present such a myositis ossificans patient whose bone and 67Ga-citrate imagings showed increased uptake in the left thigh and two foci of the right gluteal region leading to inconclusive results. Technetium-99m-MIBI imaging showed the absence of substantial uptake in these regions. ACT scan confirmed myositis ossificans. The lack of 99mTc-MIBI uptake in myositis ossificans means that 99mTc-MIBI imaging may be useful in the differential diagnosis.

Aged↗
PubMed1999

Reverse mismatched ventilation-perfusion pulmonary imaging with accumulation of technetium-99m-DTPA in a mucous plug in a main bronchus: a case report.

The phenomenon of reverse mismatched ventilation-perfusion on pulmonary scintigraphy is a fairly common occurrence. We present a patient who was experiencing decreasing oxygen saturation and had a reverse mismatched ventilation-perfusion imaging pattern associated with radiotracer retention in a main bronchus. Technetium-99m-DTPA aerosol lung imaging showed tracer retention in the trachea and right main bronchus, absent ventilation in the right lung, and normal ventilation in the left lung. Technetium-99m-MAA perfusion lung images showed normal perfusion of the left lung and some perfusion in the right lung. These findings represented a reverse ventilation-perfusion mismatch. Reverse mismatched ventilation-perfusion, or totally absent ventilation with preservation of some perfusion in the right lung, resulted in functional intrapulmonary shunting, which explained the decreasing oxygen saturation observed in this patient. A concurrent portable chest radiograph showed elevation of the right hemidiaphragm, a shift of the mediastinum to the right, deviation of the endotracheal tube, narrowing of the intercostal space of the right thorax, and collapse of the right lower lobe. The radiographic findings of underventilation of the right lung with atelectasis of the right lower lobe were due to mucous plugging the right main bronchus.

Adult↗
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↗