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Biomedical subjects

P Bloch

Publications and source records attributed to P Bloch.

At least 19 recordsLinked to original sources
PubMed1992

[Diffuse leiomyomatosis of the esophagus. Analysis of a case and review of the literature].

Diffuse leiomyomatosis of the esophagus is a rare affection which is characterized by a diffuse hypertrophy of esophageal muscles, without involvement of the muscularis mucosae. This disease involves children and young adults, occasionally associated with other localisations of leiomyomatosis. The case of a 21 year old female, successfully treated by total esophagectomy, is reported herein. In this patient, proteinuria and hematuria led to the discussion of an aspect of Alport's syndrome which is characterized by association of leiomyomatosis, deafness, cataract, and hematuria.

Adult↗
PubMed1992

[The value of computer reconstruction of the frontal and sagittal planes of the facial structures].

The authors evaluate the merits of computer reconstructions in the coronal and sagittal planes to assess the anatomy of the facial structures. If the patient can be kept motionless, the coronal plane provides information similar to those obtained by a study with direct sections. The ethmoidofrontal recesses, the lamina cribrosa, the thin relief of the middle meatus, the floor of the orbit are perfectly examined. The sagittal plane provides a new approach of the anterior and posterior cortical bone, of the frontal sinus, of the nasofrontal canal, of the ethmoidal cells, of the sphenoid sinus and of the vault of the palate.

Ethmoid Sinus↗
PubMed1991

The use of T2 distribution to study tumor extent and heterogeneity in head and neck cancer.

Demarcation of the extent of malignant tissue is essential for planning a course of radiotherapy. MR images may provide additional information for delineating the target volume because of the large difference in the proton magnetic resonance relaxation times between normal and malignant tissues. In 13 patients with head and neck tumors the distribution of the proton spin-spin relaxation times, T2, at 1.5 Tesla were evaluated throughout the physician designated target volume and normal surrounding tissue. The T2 values within the tumor were always elevated compared with normal tissue, the highest values being in the nominal center of the tumor and decreasing toward the periphery. The regional distribution of T2 values within the tumor is a measure of the tissue heterogeneity within the tumor volume. In addition, the large differences in T2 relaxation times between normal and disease tissues were used in a computer algorithm to automatically demarcate the boundary of abnormal tissue in each axial MRI section. This potentially could significantly expedite the time required to identify the target volume on multiple sections and thus remove one of the major time constraints for 3D treatment planning.

Head and Neck Neoplasms↗
PubMed1990

31P localized magnetic resonance spectroscopy of head and neck tumors--preliminary findings.

Magnetic resonance imaging (MRI) is a powerful tool for accurate assessment of the anatomic extent of head and neck neoplasms. The development of methods for spatial localization by use of multiply tuned radio frequency coils that permit the measurement of multiple nuclear MR spectra (1H and 31P) from precisely defined volumes of interest has provided a basis for integrating spectroscopy into the clinical MRI examination. This offers a means for noninvasive monitoring of relative concentrations of mobile metabolites within a tumor. With the use of imaging to determine proper coil placement, a test-retest variance of about 17% is seen on MR spectroscopy. Data are presented from MRI/MRS studies for four head and neck lesions: (1) a squamous cell carcinoma of the lip; (2) a juvenile angiofibroma extending into the nasal cavity; (3) a massive chondrosarcoma of the nasal septum; and (4) a cervical nodal metastasis of a squamous cell carcinoma of the pharynx. Spectra are evaluated by comparison of relative concentrations of phosphorus compounds. The concentrations of phosphomonoesters and phosphodiesters are significantly higher in the neoplasms studied than in normal skeletal muscle. The developing role of integrated MRI/MRS to monitor the response of malignant neoplasm to radiation therapy is discussed.

Adult↗
PubMed1990

[Post-surgical inflammatory rectal stenosis].

A case of mid rectum stenosis after pelvic surgery is reported. The conservative treatment used here seems to be the more effective compared to the cases reported in the literature.

Adult↗
PubMed1989

[Diffuse retroperitoneal lymphangioleiomatosis].

A case of diffuse retroperitoneal lymphangiomatosis manifested by oedema of the left lower limb is reported. Non-invasive exploratory methods revealed a retroperitoneal pseudo-tumoral image. At laparotomy, a retro- and subperitoneal infiltration was discovered, and histology showed benign smooth muscle proliferation developed from the muscular layer of lymph vessels. There is no known successful surgical procedure for this type of lesion, and none of the treatments tested (oophorectomy or hormonal therapy) has proved to be effective.

Adult↗
PubMed1989

The use of magnetic resonance imaging and spectroscopy in the assessment of patients with head and neck and other superficial human malignancies.

The proper demarcation of diseased tissue is important for radiation therapy planning and treatment. The volume to be irradiated is usually identified on radiographs or on x-ray computed tomography (CT) sections. Magnetic resonance (MR)-derived images of the proton T2 relaxation times in small pixel elements, typically 0.5 mm2 or less, provide significantly sharper differentiation between normal and diseased tissue. The T2 values in tissue depend on the tissue composition, histologic condition, and physiologic environment within the tumor. Furthermore, for many tumors the histogram of T2 values has a clear biphasic distribution suggesting that T2 maps may be useful for the identification of necrotic or hypoxic regions within tumors. The distribution of T2 values within the tumor bed shows the general pattern that the T2 values are elevated with a range greater than that seen in normal muscle. Elevated T2 values are not by themselves diagnostic of malignancy; however, they demonstrate the heterogeneity of the microenvironment present within a tumor. The spatial distribution of T2 values is being explored as a method for computer assistance in the delineation of the target volume for treatment planning. In addition, MR P-31 spectroscopic examinations were performed on 30 patients with squamous cell carcinomas of the head and neck. Although hampered by muscle contamination in some P-31 spectra obtained with surface coil profile localization techniques, significant trends can still be appreciated in our data. These trends include the following: (1) the P-31 spectra from malignant tissue have well-resolved spectral lines in the upfield region that correspond to Pi, phosphomonoester (PME), and phosphodiester (PDE) not usually seen in normal muscle; (2) the PDE/B-ATP and PME/B-ATP ratios are greater than unity in all cases; and (3) most of the tumors have higher PME peaks than PDE peaks. The P-31 spectra from patients treated with ionizing radiation changed during and after therapy. Some of the changes could be associated with alteration of the tumor metabolic activity or synthesis and breakdown of lipoproteins. These studies suggest that magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) studies may be useful for both radiotherapy treatment planning and the noninvasive monitoring of patients both before and during treatment.

Carcinoma, Squamous Cell↗
PubMed1989

[Massive hemobilia caused by erosion of the hepatic artery by cholelithiasis with cholecysto-duodenal fistula].

The authors present a case of gastrointestinal haemorrhage due to erosion of the hepatic artery by a gallstone trapped in the neck of the gallbladder. The unusual feature of this case resides in the exteriotisation of this haemorrhage via two anatomical routes: in the form of heamobilia via the common bile duct and in the form of gastrointestinal haemorrhage via a cholecysto-duodenal fistula. Haemostasis was achieved by ligation of the hepatic artery after failure of direct repair.

Aged↗
PubMed1989

Integrated magnetic resonance and 31p spectroscopy.

Magnetic resonance imaging (MRI) has proven to be a powerful tool for accurate assessment of the anatomical extent of head and neck neoplasms. The ability to localize precisely defined volumes of interest within tissue with measurement of multinuclear magnetic resonance spectra (1H and 31P) has provided a basis for integrating spectroscopy into the clinical MRI examination. This technique which offers a means for noninvasive monitoring of relative concentrations of mobile metabolites at specific regions within a tumor is discussed. Examples of data obtained from integrated MRI/MRS studies for representative head and neck lesions are presented. The potential role of integrated MRI/MRS to monitor the response of neoplasms to therapy is reviewed.

Carcinoma, Squamous Cell↗
PubMed1988

Portal radiographs: digital enhancement of contrast.

The quality of low-contrast portal radiographs for radiation therapy can be improved with electronic contrast enhancement. After the image is copied digitally with a laser scanner microdensitometer into 4,096 gray-scale levels (12 bits) and 1,686 X 2,048 pixels, a special software package permits linear, logarithmic, exponential, or sigmoid transformations of the optical density. The precise representation of the portal image can then be interactively adjusted to emphasize the desired anatomy. Clinical examples demonstrate the value of the digital enhancement approach.

Radiographic Image Enhancement↗
PubMed1987

Practice of 3-dimensional treatment planning at the Fox Chase Cancer Center, University of Pennsylvania.

The use of 3-dimensional (3-D) dose distributions and dose-volume histograms in radiation therapy treatment planning is illustrated on a patient with a head and neck tumor. The patient was immobilized in a rectangular tissue compensation bolus box. The treatment was planned with a 14 MeV D-T derived fast neutron therapy beam. The isodose distributions and the dose-volume histograms at multiple adjacent levels are used to evaluate the adequacy of coverage of target volumes and the doses to the normal tissues. Such dose-volume histograms are useful and practical in summarizing the dose distribution throughout the irradiated volume, assessing the degree of uniformity of the dose distribution within the target volume, quantifying the amount of normal tissue irradiated, and evaluating rival treatment plans for both particle and nonparticle beams.

Fast Neutrons↗
PubMed1987

Rapid three-dimensional treatment planning: I. Ray-tracing approach to primary component dose calculations.

Algorithms for fully three-dimensional divergent-beam radiotherapy treatment planning have been developed to achieve very high sampling of dose in heterogeneous (inhomogeneous density) tissue throughout an arbitrarily oriented patient volume, in clinically acceptable times of calculation. Dose is calculated at points along numerous rays which sample each beam. To display the dose distribution, the calculated dose values for each beam are interpolated onto rectilinear grids of (arbitrary) parallel planes, scaled for beam weight and finally merged with the weighted dose contributions of other beams. In this paper we describe and demonstrate the algorithm for the primary component of the three-dimensional photon dose distribution delivered to a patient.

Clinical Trials as Topic↗
PubMed1986

An x-ray fluorescence technique to measure in situ the heavy metal burdens of persons exposed to these elements in the workplace.

Assays of hair and body fluid concentrations may be valuable measurements of acute exposure to a heavy metal, but they do not provide insight into the total heavy metal intake when the intake is low and chronic. The use of an x-ray fluorescence technique (XRF) enables measurement of the long-term retention of various heavy metals in select tissues in vivo. XRF was used to measure the mercury content of head and bone tissue in 298 dentists with long-term exposure to mercury-containing amalgams. It was also used to evaluate the lead burden of persons suspected of having elevated lead exposure at the workplace, and to assay the lead levels in urban and rural children. These studies indicated that the x-ray fluorescence method of assaying heavy metals in vivo is noninvasive, safe, rapid, and sensitive to levels of many heavy metals that accumulate in human tissues.

Adult↗
PubMed1979

[Intestinal polyposis (author's transl)].

Recto-colonic polyposis is typical of pre-malignant lesions. Recognition and the application of appropriate treatment offer true prophylaxis against recto-colonic carcinoma in sufferers. Careful study should be made of other family members, the only way in which latent forms may be discovered before the stage of malignant change.

Colonic Neoplasms↗