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Biomedical subjects

D F Yankelevitz

Publications and source records attributed to D F Yankelevitz.

At least 55 records · Page 3Linked to original sources
PubMed1994

Lung cancer: evaluation with MR imaging during and after irradiation.

We used magnetic resonance (MR) imaging to evaluate treatment response of 10 consecutive lung cancer patients while they were receiving radiation therapy. Patients were scanned before treatment, during treatment, at completion of treatment, and if possible, at 3-month intervals thereafter. The initial tumor response to radiation was increasing signal intensity and increasing heterogeneity, best seen on T2-weighted images. Small tumors virtually disappeared, whereas larger masses remained as complex cystic structures or developed cavities. The adjacent irradiated lung parenchyma had increased signal on both the T1- and T2-weighted images as early as 17 days after start of treatment. The signal intensity continued to increase for several months after treatment, but subsequently decreased.

Adult↗
PubMed1993

Needle-tip localization for CT-guided biopsies.

Exact localization of the needle tip during CT-guided needle biopsy is important for accurate diagnosis. Using a phantom model we evaluated different methods for localization. The most reliable method was direct visualization of a distinct feature of the needle such as a notch near the needle tip. Visualization of a black shadowing artifact and review of adjacent CT images to the one used for needle tip placement were less reliable.

Artifacts↗
PubMed1993

Percutaneous CT biopsy of chest lesions: an in vitro analysis of the effect of partial volume averaging on needle positioning.

OBJECTIVE: Accurate needle biopsy of chest lesions requires knowledge of both the direction of the needle and the exact location of the tip of the needle. The purpose of this study was to analyze and illustrate the relationships between the location of the nodule, the size of the nodule, the CT slice thickness, and the needle length. An understanding of these relationships should minimize localization errors due to partial volume averaging and thus increase the accuracy of biopsies. MATERIALS AND METHODS: Geometric principles were used to determine mathematical relationships between the size of the nodule, the CT slice thickness, the length of the needle, and the direction of the needle. A styrofoam model simulating the patient and the lesion to be sampled was developed so that radiographs and CT scans of the model could be obtained with different needle placements to illustrate the phenomenon of partial volume averaging. RESULTS: The accuracy of the CT-guided biopsy can be increased by reducing the CT slice thickness, using longer needles, minimizing the distance to be traversed within the patient, and maximizing the portion of the lesion contained in the CT section used for needle tip localization. Mathematical equations developed from the in vitro model can be used to select the most appropriate CT section and the best length and angle of the needle. CT scans of the model illustrate the use of these equations. CONCLUSION: We found these principles helpful in improving the accuracy of CT needle biopsies, particularly when the lesions are very small and when an angled approach is required. Ideally, the smallest possible CT slice thickness and the longest possible needles should be used, but some practical limitations exist.

Biopsy, Needle↗
PubMed1991

Effect of radiation therapy on thoracic and lumbar bone marrow: evaluation with MR imaging.

Bone marrow suppression is often the limiting factor in the use of radiation therapy. In order to determine if MR imaging can be used to quantify bone marrow changes, we performed a serial prospective study of patients with lung cancer (six cases) and lymphoma (six cases). Quantitative and qualitative assessments of T1-weighted sagittal images, 750/33 (TR/TE), obtained at 0.6 T before, during, and after radiotherapy showed increased signal intensity in the radiated portions of the spine. These changes appeared as early as 2 weeks after the beginning of radiation, continued to increase until a maximum value was attained, and then persisted during the follow-up period of 2 years. A significantly higher (p less than .04) ratio of pretreatment to maximum posttreatment signal intensity was seen in patients with lymphoma than in those with lung cancer, and pretreatment values in patients with lymphoma were significantly lower (p less than .01). The lower pretreatment values found in the patients with lymphoma may have been due to the smaller amount of yellow marrow in these patients, who were significantly younger (33 vs 62 years). The higher ratio of pre- and posttreatment signal intensity may have been related to the larger amount of hematopoietic marrow available to undergo fatty replacement. The persistence of elevated signal intensity for as long as 2 years after radiation suggests an endpoint in the process of marrow conversion, but not reversal in the form of regeneration of hematopoietic bone marrow. Quantitative MR evaluation of bone marrow may be of considerable value as a noninvasive means of monitoring the effects of radiotherapy.

Adult↗
PubMed1989

Pleural effusions: pathogenesis, radiologic evaluation, and therapy.

The imaging of pleural effusions by plain radiography, sonography, computed tomography (CT), and magnetic resonance imaging (MRI) has greatly facilitated the planning of both initial diagnostic thoracentesis and subsequent therapeutic management. The normal anatomy and physiology of the pleura, the pathogenesis of effusions, and the clinical criteria for classifying effusions are briefly summarized. The usefulness of each imaging modality is then discussed, particularly with regard to the problems of detecting small effusions, identifying loculation of fluid, distinguishing pleural from intraparenchymal disease, and assessing the extent to which a pleural process has become organized.

Diagnostic Imaging↗
PubMed1989

The pathogenesis, radiologic evaluation, and therapy of pleural effusions.

Radiology has played a pivotal role in the management of patients with pleural effusions. By confirming the presence of an effusion and providing information regarding the size and distribution of fluid, chest radiography greatly facilitates initial diagnostic thoracentesis. Identification of even small effusions is important because these commonly occur and may have clinical significance. The development of improved antibiotics and a wider range of interventional techniques has increased the reliance on the radiologic imaging of pleural disease in order to plan appropriate therapy. The newer imaging modalities of CT and sonography have proved to be particularly valuable in detecting small effusions and demonstrating single or multiple loculations. Additional features, such as the degree to which a pleural process has become organized and whether there is adjacent lung parenchymal disease, are well assessed on CT. Experience with MR has been limited, but preliminary data suggest that it may be a valuable addition and/or alternative to CT.

Animals↗
PubMedDate not supplied

Pleural diseases: multimodality imaging and clinical management.

The parietal and visceral pleura are specialized membranes which are highly efficient in keeping the pleural space essentially dry and free of protein and particulate matter. Radiology has played a pivotal role in the understanding of pleural diseases because radiography and, more recently, computed tomography (CT), sonography, and magnetic resonance imaging (MRI) have allowed in vivo visualization of abnormalities. In addition, these newer modalities have been invaluable in guiding diagnostic and therapeutic measures. Cross-sectional imaging techniques, particularly CT, are frequently of assistance in determining whether tube thoracostomy or other surgical measures are indicated, and when these procedures should be performed. The application of newer imaging modalities in expediting the management of pleural diseases is emphasized. The anatomy, histology, and physiology of the pleura, in both normal and disease states, are also reviewed.

Diagnostic Imaging↗
PubMedDate not supplied

CT of the airways.

Explore the source record for details and available documents.

Bronchi↗
PubMedDate not supplied

MR appearance of radiation hepatitis.

The histopathologic changes of radiation hepatitis have been well described. The magnetic resonance (MR) appearance, however, has been described only in two case reports. We obtained serial MR scans of patients undergoing therapeutic irradiation for Hodgkins lymphoma to determine the time course of changes in signal intensity of the liver. We found an increased signal intensity of the irradiated portion of the liver on T2-weighted images. Changes first detected at 4 weeks following 3600 cGy to the abdomen returned to normal signal intensity within 60 days following completion of radiation therapy. One patient demonstrated a subtle increase in signal intensity of the irradiated region as early as 7 days after receiving 2000 cGy. Our results suggest that MR imaging is a useful noninvasive means of tracing the course of radiation hepatitis.

Adult↗
PubMedDate not supplied

Angulated needle placement in CT-guided percutaneous needle biopsy of the thorax.

Computed tomography (CT)-guided percutaneous needle biopsy is often necessary to evaluate small intrathoracic lesions. Not infrequently, an overlying structure such as a rib or vessel precludes insertion of the biopsy needle within the CT slice containing the lesion. Insertion and angulation of the needle at a site within an adjacent CT slice is then required. In order to determine the optimal skin-entry site and degree of angulation for biopsy needle insertion, we analyzed the geometric relationship between lesion depth, needle length, and needle angulation.

Biopsy, Needle↗
PubMedDate not supplied

Transthoracic needle biopsy. What size syringe?

Using a vacuum gauge we demonstrated that with less effort, the identical vacuum can be obtained using a 10-cc syringe as opposed to a 50-cc syringe. We recommend using a 20 cc syringe during transthoracic needle aspiration since the syringe is easier to handle and still allows sufficient vacuum to be developed, even if a small amount of air enters the syringe.

Biopsy, Needle↗
PubMedDate not supplied

Evaluation of competing tests for the diagnosis of pulmonary embolism and deep vein thrombosis, Part I.

Tests for pulmonary embolism (PE) and its most frequent source, deep vein thrombosis (DVT), include angiography, ventilation-perfusion nuclear medicine scans, venous sonography with Doppler, and contrast and radionuclide leg venography. Although selective angiography is the definitive procedure for the diagnosis of PE, the associated risk of death, although small, as well as the morbidity associated with injection of contrast agents, are high enough that alternative, less accurate, but safer diagnostic procedures are performed in an attempt to avoid the higher-risk procedure. Effective cost (EC) of each test represents the dollars spent per unit of diagnostic information and is defined as the ratio of the expected direct cost (EDC) of the test to its diagnostic performance (DU). EDC includes the base cost or charge of the test and the estimated cost of the morbidity and mortality that can be incurred in performing the test, while DU is determined from the test sensitivity and specificity. With the lowest EC as the selection criterion for the best test and representative costs, sensitivity, specificity, and morbidity and mortality rates, five different tests for PE or DVT were compared. Doppler sonography yielded the most diagnostic information per dollar spent, as its EC was the lowest, primarily because its base cost was low compared to that of the other tests. Radionuclide leg venography had the second lowest EC. Selection among the remaining three tests depended on the prevalence of PE and morbidity and mortality costs.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗