PubMed Health⌕ Search

Biomedical subjects

H Y Kressel

Publications and source records attributed to H Y Kressel.

At least 19 recordsLinked to original sources
PubMed1992

Magnetic resonance imaging of abscesses using lipid-coated iron oxide particles.

RATIONALE AND OBJECTIVES: The authors investigated whether iron oxide particles can be used as a magnetic resonance imaging (MRI) contrast agent to image abscesses in a two-stage experimental design. METHODS: Human buffy coat was incubated with iron oxide particles of different sizes and coatings. Smears of the incubation mixture were made on a glass slide and stained for iron. The percentage of iron oxide uptake was determined by counting 100 neutrophils and monocytes and scoring the number of cells that contain iron. Subcutaneous abscesses were created in the flanks of 18 Sprague-Dawley rats by injecting them with 0.1 mL of turpentine. Iron oxide was given intravenously, and the animals were imaged by MRI (1.5 T) 12 to 24 hours later. Different iron oxide coatings and doses were compared. RESULTS: The four different types of coating (constant fragment [Fc] of IgG, bovine serum albumin [BSA], lipid [Ferrosome], and dextran) had an uptake of 72% +/- 5.3%, 61% +/- 6.2%, 30.5% +/- 6.8%, and 5% +/- 2.5%, respectively. Comparison of two particle sizes (mean, 90 versus 35 nm) showed the large particles to have higher uptake (61% +/- 6.2%) compared with the small particles (6% +/- 1.8%) (P less than .001). Post-contrast imaging of the rats showed a hypointense ring around the abscess only in the animals injected with the lipid-coated agent. The effect was discernible within 12 hours after contrast injection and at a dose of 25 mumols iron/kg. Histologic sections showed phagocytic cells with iron granules in the periphery of the abscess. No hypointense ring on MRI or iron granules on histologic sections was seen around the abscess of the control animals or those injected with BSA-iron oxide or Fc-iron oxide. CONCLUSIONS: Lipid-coated iron oxide particles can be used to image abscesses by virtue of their phagocytosis into surrounding inflammatory cells. Positive uptake of these particles by human phagocytes in vitro suggests that similar results may be applicable in humans.

Abscess↗
PubMed1992

Magnetic resonance angiography of the pelvis and lower extremities. Works in progress.

Two-dimensional time-of-flight (TOF) magnetic resonance angiography (MRA) of the lower extremities has recently been rediscovered as a technique that can be used to find small vessels in the foot and leg for surgical revascularization in patients with severe peripheral vascular disease. The purpose of this article is to acquaint the reader with some of the common problems that may be encountered in this imaging technique and to show their derivations and solutions were applicable. In addition, the authors show receiver operator curve analysis of one radiologist's ability to determine the location and patency of arteries using this technique to be outstanding (AZ, 0.9737). This represents a promising new technique for imaging the arterial system in patients with severe peripheral vascular disease.

Blood Vessels↗
PubMed1992

Magnetization transfer of hepatic lesions: evaluation of a novel contrast technique in the abdomen.

The authors evaluated the technique of magnetization transfer to determine if it could enable distinction of benign from malignant liver lesions. Thirteen patients with 27 hemangiomas or cysts and 13 patients with 31 malignant liver lesions underwent magnetic resonance imaging. Hepatic malignancies demonstrated magnetization transfer similar to that of the liver. However, hemangiomas and cysts showed significantly less magnetization transfer than malignant liver lesions. Gradient-recalled-echo imaging with the off-resonance saturation pulse showed increased lesion contrast compared with the liver for hemangiomas and cysts but not for malignancies. On the basis of signal intensity measurements alone (ie, ignoring morphologic criteria), the magnetization transfer studies showed an area under the receiver operating characteristic curve of 0.96 for distinguishing benign from malignant liver lesions. Though the separation of these two groups was imperfect, it was comparable with that achieved with qualitative analysis of signal intensity ratios at spin-echo imaging.

Cysts↗
PubMed1992

The seminal tract in patients with ejaculatory dysfunction: MR imaging with an endorectal surface coil.

Twenty-six patients with signs and symptoms of ejaculatory dysfunction (hemospermia, hypospermia, oligospermia, or painful ejaculation) were examined with high-resolution MR imaging with an endorectal surface coil. Findings were abnormal in 15 patients. Abnormalities detected included four cases of müllerian cysts, three cases of wolffian cysts, one case of anaplastic prostatic carcinoma, and various noncystic abnormalities of the seminal vesicles and ejaculatory ducts, including ejaculatory duct obstruction and seminal vesiculitis. In all cases, depiction of both the normal and abnormal anatomy of the entire seminal tract, including the vas deferens, seminal vesicles, and ejaculatory ducts, was excellent. This depiction of the detailed anatomy of the prostatic cysts made it possible to suggest specific diagnoses. Our results show the value of MR imaging with an endorectal surface coil in the examination of patients with ejaculatory dysfunction.

Adolescent↗
PubMed1992

First principles of fast spin echo.

Fast spin echo (FSE), a variant of the rapid acquisition with refocused echoes pulse sequence, is now being widely considered as an alternative to conventional spin echo for proton density and T2-weighted imaging. Although the medical experience with this sequence is relatively limited, relevant aspects of the technique have been well understood in the context of spectroscopic applications for many years. This article attempts to portray the subject in an appropriate historical context. Such a viewpoint promotes a deeper understanding of the artifacts, determinants of contrast, and future evolution of FSE. Hopefully, this may not only be of benefit in the design of optimal clinical imaging protocols for current state of the art but may also be of use in fashioning the criteria by which new developments in this field may be judged.

Artifacts↗
PubMed1992

Evaluation of gynecologic malignancy by magnetic resonance imaging.

Currently, MR imaging has demonstrated the greatest accuracy and has potentially the greatest clinical utility for the staging of cervical carcinoma. Endometrial carcinoma also can be staged by MR imaging with reasonable accuracy, although the clinical indications for preoperative endometrial carcinoma staging are less clear. MR imaging has unparalleled capacity for the tissue characterization of adnexal disease and has demonstrated utility for diagnosis of common adnexal masses such as pedunculated leiomyoma, endometrioma, and ovarian dermoid. Its use in the evaluation or staging of ovarian, vaginal, and vulvar carcinoma has not been evaluated fully. MR imaging can demonstrate complications of radiation therapy and surgery and can distinguish most recurrent carcinomas from postradiation fibrosis. New techniques such as arrayed use of surface coils, endoluminal surface coils, fast spin-echo acquisitions, and contrast agents show promise for contributing to the already rapid pace of technologic advancement in the field of MR imaging of the female pelvis.

Female↗
PubMed1991

Integrated magnetic resonance imaging and phosphorus spectroscopy of soft tissue tumors.

Eighteen patients with soft tissue masses underwent integrated magnetic resonance imaging (MRI) and phosphorus spectroscopy (31P-MRS) to evaluate benign and malignant tumor morphology and metabolism. Spectra from soft tissue tumors had a significantly higher proportion of phosphate in the low-energy portion of the 31P spectrum (P less than 0.001) with a concomitant decrease in phosphocreatine (P less than 0.01) compared with 31P spectra from normal muscle. Malignant tumors had a mean pH of 7.35 +/- 0.13 which was greater than that of muscle tissue with a mean pH of 7.08 +/- 0.07 (P less than 0.001). All tumors had greater relative levels of phosphomonoesters, inorganic phosphate, and phosphodiesters compared with those in muscle tissue but considerable variability among tumors was noted due to tumor size, extent of tumor necrosis, and muscle contamination. Integrated MRI/MRS studies are necessary to provide exact localization of the tumor and a more correct interpretation of the 31P-MRS data.

Adolescent↗
PubMed1991

MRI appearance of femoral head osteonecrosis following core decompression and bone grafting.

We used magnetic resonance imaging (MRI) to evaluate retrospectively 32 hips with avascular necrosis of the femoral head before and after core decompression and bone grafting. At a median follow-up time of 15 months, 4 of 9 large lesions had undergone femoral head collapse; 2 small lesions had decreased in size; and 14 small, 6 moderate, and 5 large lesions were unchanged. One hip with biopsy-proven avascular necrosis had diffuse marrow edema which resolved after surgery. The signal pattern within the lesions was analyzed in 17 hips. Fifteen lesions were unchanged, while one fat-like lesion became fibrous-like and one edema-like lesion resolved. Analysis of the femoral neck marrow signal in one patient revealed that premature fatty marrow conversion had reverted to hemopoietic marrow 2 years after surgery. Most lesions that appeared stable on MRI were clinically stable or improved. MRI can demonstrated changes in size and signal characteristics as well as femoral head collapse after core decompression and bone grafting. Changes in the surrounding marrow signal, including resolution of marrow edema and reconversion from fatty to hemopoietic marrow, can also be detected.

Adult↗
PubMed1991

In vivo and ex vivo magnetic resonance imaging evaluation of early disc degeneration with histopathologic correlation.

The in vivo and ex vivo microanatomic appearance of early disc degeneration were identified by magnetic resonance imaging and correlated with their respective histopathologic findings. Five cadaver spines (18 discs) and 25 patient studies (122 discs) all imaged at 1.5 Tesla were studied. Two signs of early degenerative disc disease were found: infolding and the central dot. Infolding of the central fibers of the outer annulus coalesced into a central dot of low signal intensity that was seen on both the ex vivo and in vivo images. Infolding was seen 29 of 122 times, and the central dot was observed 15 to 122 times on the in vivo images. A later form of degenerative disc disease was identified as a separation of the nucleus pulposus from the hyaline cartilage end-plate. This separation was seen as a linear area of either low or high signal intensity on the ex vivo images but only as a band of high signal intensity on the in vivo spin-echo 2,500-msec/80-msec images. Only 7 of 122 in vivo discs showed this separation. Internal herniation of nucleus pulposus into the outer annulus was seen only on the ex vivo images. Early degenerative disc disease may exist before there is loss of disc height or signal intensity on the long time-to-repetition (TR)/time-to-echo (TE) magnetic resonance images.

Adult↗
PubMed1991

Prostate cancer: local staging with endorectal surface coil MR imaging.

Endorectal surface coil magnetic resonance (MR) imaging was used to stage the local extent of prostate cancer in 22 patients. The endorectal coil images were acquired with a 10-12-cm field of view and a 4-mm section thickness. All pathologic specimens were reviewed by one pathologist. Endorectal surface coil MR imaging was 82% accurate in the differentiation of stage B from stage C cancer. One case was overestimated, and three cases were underestimated. The three underestimated cases consisted of two cases of microscopic capsular invasion and one case of minimal seminal vesicle invasion. In a comparison of retrospective, blinded readings of endorectal coil and body coil images, there was an average improvement in accuracy of 16% in staging prostate cancer with endorectal coil images.

Carcinoma↗
PubMed1991

Trabecular structure: preliminary application of MR interferometry.

A new approach to probe the structure of trabecular bone in the vertebral bodies in humans was evaluated, and preliminary data are presented. The proposed method is based on the hypothesis that the presence of two physical phases--bone and bone marrow--causes a magnetic field distribution across the imaging voxel. The resulting spread in resonance frequency produces line broadening, which is measured as the decay rate of the region of interest signal intensity that has the properties of an interferogram. The interferogram is the result of two principal chemically shifted components of bone marrow--fat and water--getting in and out of phase with one another while being attenuated by T2* processes from the magnetic field distribution within the measuring volume. The time constant for the decay (T2*) can then be obtained by means of curve-fitting techniques. T2* in healthy persons is found to increase slightly with age. However, patients with osteoporosis (low bone mineral density and/or spine compression fractures) have significantly prolonged T2* values, which are interpreted as arising from an increase in the intertrabecular space.

Adolescent↗
PubMed1991

High-signal-intensity rim surrounding uterine leiomyomas on MR images: pathologic correlation.

A high-intensity rim surrounding uterine leiomyomas was identified on T2-weighted magnetic resonance (MR) images in five of 13 patients with histopathologically confirmed leiomyomas. These peripheral high-intensity rims were not associated with subject age or with size, location, or degeneration of the leiomyomas. Histologic examination revealed markedly dilated lymphatic vessels, dilated veins, edema, or a combination of these features to correspond to the location of the high-intensity rims. These benign causes of high intensity in the myometrium should not be confused with clinically important processes such as adenomyosis or invasion by endometrial carcinoma.

Adult↗
PubMed1991

Cervical carcinoma: MR imaging with an endorectal surface coil.

Ten consecutive patients with biopsy-proved invasive cervical carcinoma underwent magnetic resonance (MR) imaging with both a standard body coil and with an endorectal surface coil. The endorectal coil provided a markedly improved signal-to-noise ratio, enabling the use of small fields of view; thus, the images had significantly improved in-plane resolution. The images were assigned an MR imaging stage based on the clinical staging system of the International Federation of Gynecology and Obstetrics. Vaginal wall, vaginal fornix, parametrium, and pelvic side-wall invasion by tumor were all well demonstrated. When compared with body coil images, the endorectal coil images provided increased anatomic detail and demonstrated tissue planes between tumor and normal structures that were not seen on the body coil images. This preliminary investigation indicates that use of an endorectal surface coil is a promising technique to obtain high-resolution images of the female genital tract. This technique has the potential to improve the accuracy of staging for cervical carcinoma.

Adult↗
PubMed1991

Hepatic colorectal metastases: correlation of MR imaging and pathologic appearance.

Results of magnetic resonance (MR) imaging examinations for 76 patients with proved colorectal metastases to the liver were retrospectively reviewed. Signal intensity and morphologic patterns of 157 lesions were scored. The morphologic patterns were correlated with the histologic material obtained at segmental hepatic resections or excisional biopsies in 33 patients. In 154 lesions (98%) colorectal metastases to the liver were found to be hyperintense on MR images acquired with a long repetition time/echo time; in 77 lesions (49%) central low-signal-intensity changes were seen. Virtually all larger lesions demonstrated areas of low signal intensity within the tumor. These areas were found to reflect histologic findings of coagulative necrosis and desmoplasia within the tumor. Peripheral hyperintense halos around central hypointense areas encompassed the growing tumor margin and variable degrees of cell necrosis. Hypointense peripheral rims, which correspond to abnormalities of surrounding hepatic parenchyma, were seen in 40 lesions (25%). This sign should not be assumed to represent the fibrous pseudocapsule of primary hepatic malignancy. No correlation between tumor grade (differentiation) and tumor morphology was observed.

Adenocarcinoma↗
PubMed1991

Combined chemical-shift and phase-selective imaging for fat suppression: theory and initial clinical experience.

Incomplete fat suppression with a chemical-shift-selective (CHESS) or phase-selective (Dixon) technique is partially due to the olefinic fat component, which precesses at the same frequency as water. The authors developed a new method of fat suppression--the opposed-fat saturation (OP-ES) sequence--that combines both techniques to obtain superior fat saturation. Fat suppression was verified in phantom studies, which showed that the CHESS portion can eliminate most of the aliphatic fat signal except for a small residual component because of steady state effects and magnetic field imperfections. This residual component is cancelled by the olefinic fat with the phase-selective opposed portion of the sequence. Furthermore, this sequence was superior to another hybrid technique, chopper Dixon in combination with CHESS. When used in 10 healthy volunteers, the OP-FS sequence showed consistently better suppression of the subcutaneous and retroperitoneal fat compared with CHESS alone. Additional advantages for clinical abdominal imaging include its compatibility with respiratory compensation, use of a single excitation, and ease of implementation with gradient-echo imaging. Preliminary application in 10 patients illustrated other potential advantages, including clarification of fat-containing diseases and increasing conspicuity of some lesions.

Adipose Tissue↗
PubMed1991

Rectal carcinoma: staging at MR imaging with endorectal surface coil. Work in progress.

To increase the accuracy of local staging of rectal carcinomas at magnetic resonance (MR) imaging, the authors placed on endorectal coil mounted on a balloon in a position adjacent to the lesion. Use of such a local coil resulted in increased signal-to-noise ratio compared with use of a body coil; higher-resolution images were obtained because the field of view was decreased. The depth of wall invasion by rectal carcinoma was correctly staged with endorectal MR imaging in 11 of 12 patients. In the detection of perirectal adenopathy, use of MR enabled correct identification of positive perirectal nodes in four of seven patients (57%). There were no false-positive diagnoses of perirectal adenopathy at MR. Endorectal MR imaging is an evolving and promising technique for the local staging of rectal carcinomas, but further studies are needed to demonstrate its efficacy.

Female↗