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Biomedical subjects

K Shaffer

Publications and source records attributed to K Shaffer.

At least 19 recordsLinked to original sources
PubMed2003

Dynamic infrared imaging of newly diagnosed malignant lymphoma compared with Gallium-67 and Fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography.

Staging and therapy monitoring of malignant lymphomas relies heavily on imaging using arbitrary size criteria from computed tomography (CT) and sometimes non-specific radionuclide studies to assess the activity of the disease. Treatment decisions are based on early assessment of the response to therapy and the residual volume of the disease. Our initial experience is reported using a new noninvasive, inexpensive, and reproducible passive imaging modality, Dynamic Infrared Imaging (DIRI), which may add a new dimension to functional imaging. This system relies on its ability to filter the raw infrared signal using biological oscillatory behavior. It detects and analyzes minute oscillations of temperature and heat distribution in tumors.

Adult↗
PubMed2001

Clinical competence assessment in radiology: introduction of an objective structured clinical examination in the medical school curriculum.

RATIONALE AND OBJECTIVES: Traditional oral and written examinations can be limited in predicting future clinical performance. Therefore Objective Structured Clinical Examinations (OSCEs) have been introduced in other specialties. The authors assessed their value in radiology. MATERIALS AND METHODS: The study includes 122 Harvard medical students who undertook 1-month compulsory clerkships at one of three hospitals (A, B, or C) in their 3rd and 4th year and a compulsory OSCE in their 4th year. The OSCE was constructed from five cases. Each had eight or nine standardized questions designed to test, within a set time, the perception of essential findings, their interpretation, and clinical judgment (maximum possible score, 100). Clerkship grades were high honors (score of 3), honors (score of 2), satisfactory (score of 1), and fail (score of 0). Predictors of OSCE scores-clerkship grade and affiliated hospital-were modeled as linear functions. Time elapsed between clerkship and OSCE was modeled as a nonlinear function. RESULTS: Although there was a positive relation between clerkship grade and OSCE grade, it accounted for an increase of only 5.7% in OSCE score per clerkship grade and did not predict performance of individual students. Students who trained in hospital B showed significantly higher OSCE grades. OSCE scores were highest when the examination was taken 8 months after the clerkship. CONCLUSION: The OSCE may be useful to uncover deficits in individuals and groups beyond the ones detected with traditional clerkship evaluations and provide guidance for remediation. The improved performance after additional clinical exposure suggests that the OSCE may be well suited to test the integration of radiologic and clinical knowledge.

Clinical Clerkship↗
PubMed2000

Profile of medical student teaching in radiology: teaching methods, staff participation, and rewards.

RATIONALE AND OBJECTIVES: The purpose of this study was to collect demographic information about radiology departments and rewards for teaching activities, as well as the impact of new digital imaging methods on teaching. MATERIALS AND METHODS: Two surveys were conducted of directors of medical school clerkships in radiology. The initial survey focused on numbers of staff and students, courses taught, and perception of rewards for teaching. The follow-up survey more specifically addressed teaching methods. RESULTS: Sixty-nine (50%) of the initial surveys sent to 139 departments and 46 (39% of a total of 119) of the follow-up surveys were returned. Clerkship directors spent an average of 9 hours per week teaching and performing administrative tasks, with most given no additional time off. Eighty-four percent of departments provide either no or insignificant rewards for teaching. Many departments have integrated the use of computers in teaching, and most have computers that students use during the radiology course. At the same time, digital imaging and picture archiving and communication systems (PACS) are used, or will be used within 1 year, in most departments. CONCLUSION: Clerkship directors receive little compensation in terms of time and rewards for medical student teaching. Teaching methods are evolving in response to the increasing use of computers, digital imaging, and PACS for at least part of the workload in most radiology departments.

Clinical Clerkship↗
PubMed1999

Role of radiology for imaging and biopsy of solitary pulmonary nodules.

Both imaging and image-directed biopsy play a major role in evaluating solitary pulmonary nodules. Imaging is used to determine whether the nodule is actually solitary or if multiple nodules are present. Once a nodule has been detected, imaging techniques can be used to characterize the nodule in terms of whether it is likely benign or malignant. As technology has improved, smaller nodules are now more easily detected, which may create a management dilemma. With the advent of video-assisted thoracoscopic techniques, however, sampling of these lesions has become much easier. Once a solitary pulmonary nodule is detected, image-guided biopsy is often considered, which can be undertaken using CT or fluoroscopy. Technical limitations, the location of the solitary pulmonary nodules, and clinical conditions must be considered when determining the role of image-guided biopsy. Other concerns include the role of on-site cytology and the use of more recent technical advances. Image-guided biopsy should be used as part of a multimodality approach to patient management, and decisions should be discussed with the radiologist and other caregivers to determine the cost-effectiveness and safety of the procedure for each patient.

Biopsy, Needle↗
PubMed1998

Microlithographic determination of axonal/dendritic polarity in cultured hippocampal neurons.

High resolution substrates, created using patterned self-assembled monolayers, are shown to direct axonal and dendritic process extension at the level of a single hippocampal neuron. Axons and dendrites were identified using morphological characteristics and immunocytochemical markers. Patterns were formed on glass coverslips from a co-planar monolayer of cell adhesive aminosilanes and non-adhesive fluorinated silanes. On patterned surfaces, the percentage of the total number of cells attached to the 0.71 mm2 substrate field with compliance to the 25-micron diameter 'somal adhesion site' reached 41 +/- 7% (mean +/- S.D., 428 cells counted). A total of 76 +/- 11% of cells that adhered to a somal attachment site developed a lone process > or = 100 microns oriented in the direction of the continuous aminosilane pathway which was shown to express axonal markers. Cells on either the fluorinated silane, which is non-permissive for neurite outgrowth, or localized on an aminosilane region only 5 microns wide failed to extend major processes. This approach is amenable to a variety of industry standard fabrication techniques and may be used to study the role of fine scale spatial cues in neuronal development and synapse formation.

Animals↗
PubMed1997

Imaging and medical staging of lung cancer.

Chest radiography and CT scanning remain the backbone of imaging of lung cancer, and they continue to play a pivotal role in staging. This role is best defined as providing a roadmap to oncologists and surgeons to assist in definitive pathologic staging, rather than as competing with these methods. Much more sensitive and specific imaging tools must be developed before noninvasive radiologic staging can replace surgical staging. New nuclear medicine techniques including PET scanning and use of monoclonal antibodies linked to radionuclides offer the best hope for such definitive radiologic staging in the future.

Humans↗
PubMed1997

Radiologic evaluation in lung cancer: diagnosis and staging.

Radiology and surgery are not competing but are complementary modalities in the care of patients with lung cancer. In certain areas, such as evaluation of the solitary pulmonary nodule, radiologic studies can have an important impact on patient care. Mediastinal staging with imaging studies is inexact, and CT may be most effective as a road map for more definitive surgical staging. MRI currently offers no advantages over CT in staging of the mediastinum but can be helpful in evaluation of parts of the chest not well demonstrated on axial images. A discussion of newer nuclear medicine imaging modalities is included.

Humans↗
PubMed1996

Analysis of prostate and seminal vesicle motion: implications for treatment planning.

PURPOSE: To quantify prostate and seminal vesicle positional changes (target motion) between treatment planning and delivery, and to identify the factors contributing to target motion. METHODS AND MATERIALS: Thirty patients with adenocarcinoma of the prostate were prospectively evaluated by analyzing two sequential planning computerized tomography (CT) scans (S1, obtained prior to treatment, and S2, obtained during the fourth week of treatment) for each patient. All anatomical volumes of interest (soft tissue and bony) were reconstructed from transverse CT images and projected onto anterior and lateral beam's-eye view projections. Positional changes between S1 and S2 were eliminated by applying a rigid body translation and rotation. Target motion was then measured by recording the positional change between S1 and S2 at the edges (right, left, superior, inferior). Potential correlation of target motion with bladder volume, rectal volume, and rectal diameter changes were evaluated by linear regression analysis. RESULTS: Neither the prostate nor seminal vesicles remained fixed with respect to bony anatomy between S1 and S2. The distribution of positional changes were generally small (< 0.5 cm), but maximum displacements of 1.5-2.2 cm did occur, particularly in the lateral view. In this study, bladder volume changes between the scans were small and did not correlate with target motion (P = 0.67). Both rectal volume and rectal diameter changes correlated with target motion for both the prostate (p = 0.004 and 0.005, respectively) and seminal vesicles (p < 0.001 and < 0.001, respectively). However, neither the initial rectal volume nor the initial rectal diameter could be used to predict subsequent target motion when evaluated either singly or as part of a multiple regression model. CONCLUSIONS: Target motion occurs during the course of treatment planning and delivery and should be considered when designing conformal radiation fields. Although the target position at the time of planning CT may differ substantially from the mean treatment position, target motion cannot be predicted by evaluating simply measured parameters from a single scan, or double scan sequence.

Adenocarcinoma↗
PubMed1996

Usefulness of the routine magnification view after breast conservation therapy for carcinoma.

PURPOSE: To assess the usefulness of the routine supplementary magnification view in patients who have undergone breast conservation therapy. MATERIALS AND METHODS: Four hundred seventy-one mammograms in 392 patients were evaluated. Conventional craniocaudal and mediolateral oblique views were obtained in each patient. After a preliminary interpretation was made, a magnification view of the excision site was evaluated and any additional information was documented. RESULTS: In 115 examinations (24%), the magnification view was considered necessary to better evaluate equivocal or questionable calcifications seen on standard views. In 18 cases (4%), review of the magnification view influenced the decision to perform biopsy. None of the magnification views that were considered unnecessary caused the interpretation made from conventional views to be altered. CONCLUSION: Magnification mammographic views should be obtained in patients who have undergone breast conservation therapy only when considered necessary after review of findings on conventional views.

Breast Neoplasms↗
PubMed1996

Primary mediastinal large-B-cell lymphoma: radiologic findings at presentation.

OBJECTIVE: Primary mediastinal large-B-cell lymphoma was recently reclassified as a distinct clinical entity. We wished to review the imaging findings for this disease and to compare the findings with those for other disorders with a similar appearance. MATERIALS AND METHODS: We retrospectively reviewed plain films, gallium scintigrams, MR images, and CT scans for 43 patients with primary mediastinal large-B-cell lymphoma. RESULTS: All but one lesion arose in the anterior mediastinum. Areas of fluid attenuation within the masses were evident on CT scans in 50% of cases. Pleural effusions were seen by chest radiography in 33% of patients. Pericardial effusions were present in 32% of patients who underwent CT scans. Of the 21 patients who underwent gallium scintigraphy, all were reported to have positive findings. Also, MR imaging showed evidence of superior vena cava syndrome in one patient. CONCLUSION: Primary mediastinal large-B-cell lymphoma typically is seen as a bulky anterior mediastinal mass that often contains areas of necrosis.

Adult↗
PubMed1995

Scintigraphic and radiographic patterns of skeletal metastases in breast cancer: value of sequential imaging in predicting outcome.

OBJECTIVE: To determine whether temporal changes in scintigraphic and bone radiographic findings have prognostic significance in patients with skeletal metastases from breast cancer. DESIGN: Clinical information and films were retrospectively reviewed in 101 randomly selected patients with skeletal metastases. Images from sequential bond scans and bone radiographs were correlated with survival after detection of the metastases. RESULTS: Time to detection of skeletal metastases and the length of time for which patients were classified as radiologically stable after development of skeletal metastases correlated with survival (r = 0.843; r = 0.821, respectively). Failure to develop a radiographically and scintigraphically stable pattern after treatment was associated with significantly decreased survival compared with the rest of the patients (mean survival 2.1 +/- 1.3 years vs 4.3 +/- 2.3 years; p < 0.001). Scintigraphic regression of metastases was associated with significant survival benefit and longer stabilization of disease compared to all other patterns (mean survival 5.0 +/- 2.7 years of regressive disease vs 3.7 +/- 1.9 years for stable disease and 2.2 +/- 1.3 years for progressive disease; p < 0.001). CONCLUSIONS: Sequential scintigraphic and radiographic imaging is useful in breast cancer patients not only for detection of metastases and monitoring of treatment effect, but also because these studies provide valuable prognostic information.

Adult↗
PubMed1994

Thoracic lymphangioma in adults: CT and MR imaging features.

OBJECTIVE: Lymphangiomas are rare benign tumors most often seen in childhood. When they occur in adults, radiologic diagnosis can be difficult. A retrospective study of the CT and MR appearances of thoracic lymphangiomas in adult patients was performed in order to describe the range of radiologic features of these tumors. MATERIALS AND METHODS: Cases of adult lymphangioma at three institutions were identified in the records of 19 patients, predominantly female, 18-67 years old. RESULTS: The most common CT appearance was a smoothly marginated cystic mass. Unusual features included calcification, spiculated margins, and homogeneous soft-tissue attenuation. The majority of cases were located in the anterior or superior mediastinum. Unusual locations included the pericardium, pulmonary hilum, and pulmonary parenchyma. Signal characteristics on MR images varied. CONCLUSION: The radiographic appearance of lymphangiomas in the chest in adult patients is varied. The diagnosis cannot be suggested on the basis of radiologic studies alone.

Adult↗
PubMed1994

Expediting the turnaround of radiology reports: use of total quality management to facilitate radiologists' report signing.

OBJECTIVE: The purpose of this study was to determine whether total quality management techniques could be used to speed radiologists' performance on the task of signing reports. SUBJECTS AND METHODS: Total quality management represents a group of tools that can be used to improve the functioning of complex processes in the workplace. The steps involved in our total quality management project were as follows: (1) commit to improving radiologists' performance, (2) commission an interdisciplinary study team, (3) propose hypotheses for the causes of signing delays, (4) identify the key issues constraining performance (Pareto analysis), (5) intervene to correct systematic problems in a test system, (6) evaluate the results of intervention on radiologists' report signing performance, and (7) hold the gains achieved by the intervention. An interdisciplinary study team identified five key obstacles to prompt signing of reports: (1) radiologists' absence from the department when reports were available for signing (e.g., nights and weekends), (2) dysfunctional hand-off between transcriptionist and radiologist, (3) requirement that a fellow or resident sign before a staff radiologist, (4) lack of a system for signing by proxy (if primary radiologist is away), (5) perceived lack of impact of signed report on clinical decision making. RESULTS: Interventions included (1) providing home computer terminals, (2) implementing a buddy system for proxy signing, (3) eliminating the requirement for a signature from a fellow or resident, (4) teaming groups of radiologists with specific transcriptionists, and (5) streamlining transcription service. When these enhancements were used in a test system, the mean time required to sign reports decreased 59% from 26.0 +/- 8.4 hr (mean +/- standard error) in the baseline period to 10.6 +/- 2.9 hr (in the enhanced period, p = .05). CONCLUSION: We conclude that total quality management methods can accelerate radiologists' signing of reports.

Authorship↗
PubMed1994

The job market for radiology residents and fellows graduating in 1994.

OBJECTIVE: In response to anecdotal reports of grave deterioration in the job market for graduates of radiology training programs, the American College of Radiology undertook a systematic appraisal of this job market for 1994. MATERIALS AND METHODS: Between mid-April and mid-May 1994, the American College of Radiology surveyed 40 directors of randomly chosen diagnostic radiology training programs and 20 directors of randomly chosen radiation oncology training programs. We achieved a response rate of 80% or more in both categories. The survey asked, among other questions, the number of graduates, how many had jobs, the number of offers received by graduates this year and last, and how difficult the job market was relative to recent years. RESULTS: Directors reported that 96% of graduating residents and 86% of graduating diagnostic fellows had commitments for positions. Of those with commitments, 94% of residents and 84% of diagnostic fellows were reported to have jobs that reasonably matched their training and job goals. Program directors estimated that the average graduate received two job offers but, on average, rated the job market as somewhat more difficult than was typical of recent years and reported that 1993 graduates had received more job offers. Plans to change size were reported for one fourth of programs, but the job market situation was not an important reason for these planned changes. CONCLUSION: Although the overwhelming majority of 1994 graduates obtained jobs, and these overwhelmingly were jobs of interest, program directors reported that the job market was weakening. Given the changes in the socioeconomic environment--managed care, for example--and the changing job market, training programs should give more attention to the job market in planning for changes in size.

Data Collection↗
PubMed1993

Large-cell and immunoblastic lymphoma of the mediastinum: prognostic features and treatment outcome in 57 patients.

PURPOSE: A retrospective study was performed to define clinical characteristics and therapeutic outcome for patients with large-cell and immunoblastic lymphoma of the mediastinum. PATIENTS AND METHODS: Fifty-seven patients who presented with primary, mediastinal large-cell and immunoblastic lymphoma were retrospectively studied to determine initial sites of disease, radiologic characteristics, treatment, outcome, and factors that have prognostic significance for progression-free and overall survival. RESULTS: Fifty-six of the 57 patients had disease that was confined to sites above the diaphragm. Bulky disease and extensive intrathoracic infiltration were common in these patients. All patients were treated with intensive chemotherapy regimens, and 44% of patients received chest irradiation. The overall 5-year survival by Kaplan-Meier estimation was 50% with a freedom-from-relapse rate of 45%. Predictors of disease relapse after chemotherapy included the presence of a pleural effusion (P = .015), a number of involved extranodal sites (P < .01), and a lactic dehydrogenase (LDH) ratio > 3.0 (LDH value/upper limit of assay; P = .04) as well as an incomplete treatment response as evidenced by residual mass on chest radiograph (P = .02) or persistent gallium 67 avidity (P = .01) after chemotherapy. Predictors of decreased survival included the presence of pleural effusion (P = .001), the number of involved extranodal sites (P = .022), and a positive posttreatment 67Ga scan (P = .027). CONCLUSION: Patients with primary mediastinal large-cell and immunoblastic lymphoma have an approximate 50% chance of surviving disease-free after initial therapy. The presence of pleural effusion at presentation was associated with an extremely poor outcome. Bulk disease per se was a negative predictive factor only in patients without pleural effusions when compared with patients who did not have bulk disease. In addition, all patients with involvement of two or more extranodal sites relapsed when treated with standard chemotherapy.

Actuarial Analysis↗
PubMed1993

Identification of internal mammary lymph nodes: value of the frontal chest radiograph.

The article describes eight patients with enlarged internal mammary lymph nodes visualized on the frontal plain chest radiograph. Enlarged internal mammary lymph nodes cast shadows that initially may be mistaken for a mediastinal or pleural abnormality. Although the lateral film alone may suggest these nodes, the findings on the frontal film help lateralize the abnormality.

Female↗