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Biomedical subjects

H Y Kressel

Publications and source records attributed to H Y Kressel.

At least 19 recordsLinked to original sources
PubMed1994

Hepatic abscesses: MR imaging findings.

PURPOSE: To determine magnetic resonance (MR) imaging features that characterize hepatic abscesses. MATERIALS AND METHODS: Clinical records and MR studies of 18 patients with proved hepatic abscesses were evaluated. The abscesses were pyogenic in 15 patients, fungal in two patients, and amebic in one patient. RESULTS: A total of 122 lesions were identified. Most were round (n = 114) with sharp borders (n = 99), hypointense on T1-weighted images (n = 73), and very hyperintense on T2-weighted images (n = 88). After injection of gadopentetate dimeglumine in 43 lesions, all 43 enhanced with sharp margins and 37 showed rim enhancement. All abscesses followed up diminished in size (50 of 50), and perilesional edema resolved before the central cavity did. CONCLUSION: MR imaging findings seen in hepatic abscesses include high signal intensity on T2-weighted images (72%) and perilesional edema (43 of 122 [35%]). Rim enhancement (86%) and increased conspicuity (35 of 43 [81%]) were found after injection of gadopentetate dimeglumine.

Adult↗
PubMed1994

Rectal tumor stage: correlation of endorectal MR imaging and pathologic findings.

PURPOSE: To develop magnetic resonance (MR) imaging criteria for staging rectal cancer. MATERIALS AND METHODS: Thirty-six patients with rectal tumors underwent MR imaging with an endorectal surface coil. MR images were compared with specimens from the resected tumor. RESULTS: Rectal wall layers were reliably demonstrated. The MR imaging-determined tumor stage agreed with pathologic findings in 81% of cases. A retrospective review found the integrity of the rectal wall layers at the lesion center an accurate criterion for interpreting the local extent of the lesion. Lymph nodes as small as 2 mm were demonstrated. Although sensitive for demonstrating perirectal adenopathy, MR imaging had a specificity of only 72% for N1 disease. CONCLUSION: Endorectal surface coil MR imaging shows promise for staging rectal lesions. Additional studies are necessary to further establish criteria for interpreting the images.

Humans↗
PubMed1994

MR imaging with spatial modulation of magnetization in the evaluation of chronic central pulmonary thromboemboli.

PURPOSE: To assess the diagnostic value of magnetic resonance (MR) imaging with SPAMM (spatial modulation of magnetization) in the identification of chronic central pulmonary thromboemboli. MATERIALS AND METHODS: Twelve patients with pulmonary hypertension and five healthy volunteers were prospectively studied with a 1.5-T MR imaging system. The SPAMM technique was integrated into a conventional cardiac-synchronized spin-echo (SE) sequence. Six of the 12 patients had central thromboemboli. RESULTS: In the healthy subjects, intravascular stripes in the central pulmonary arteries disappeared as a result of flow within 100 msec after the R wave. Areas of persistent stripes were identified in seven of eight central pulmonary arteries with thromboemboli. Conversely, in the 16 central pulmonary arteries without clot, intraluminal stripes disappeared despite the presence of flow-related signal (sensitivity = 88%, specificity = 100%, accuracy = 96%). CONCLUSION: SPAMM appears to be a simple and effective technique for differentiating central pulmonary arterial thromboemboli from flow-related signal frequently observed with pulmonary hypertension.

Adult↗
PubMed1994

Magnetic resonance imaging in cervical carcinoma: diagnosis, staging, and follow-up.

Clinicians have long looked for an imaging modality that can provide accurate and useful information on cervical carcinoma. In the past 10 years, magnetic resonance imaging (MRI) has come to play an important role in evaluating patients with this disease before treatment and in monitoring them afterward. Before treatment, MRI can accurately depict tumor size (volume) and extension. MRI thus has the potential to supplant the traditional clinical International Federation of Gynecology and Obstetrics (FIGO) staging system for this disease, which is based on clinical findings and is inherently subjective. Promising areas of research include endorectal, endovaginal, and phased-array coils.

Female↗
PubMed1993

The effect of dietary protein depletion on hepatic 5-fluorouracil metabolism.

BACKGROUND: Protein calorie malnutrition, which is highly prevalent in tumor-bearing hosts, increases toxicity to 5-fluorouracil (5-FU), but the mechanisms are unclear. This study investigated the effects of protein depletion on 5-FU in vivo hepatic metabolism using F19-nuclear magnetic resonance spectroscopy (19F-NMRS). METHODS: Rats received normal (21.5%) or low (2.5%) protein diet for 25 days. 5-FU was injected intraperitoneally, and hepatic fluorine spectra were obtained. Parallel experiments were conducted to determine serum 5-FU pharmacokinetics using high-performance liquid chromatography (HPLC) and to measure hepatic dihydropyrimidine dehydrogenase (DPD) activity. RESULTS: The mean time of initial detection of fluoro-beta-alanine and the mean duration of the 5-FU signal in the liver were significantly prolonged in the low-protein group. 5-FU clearance and hepatic DPD activity were significantly lower in the low-protein group. Low-protein animals demonstrated increased toxicity, with diarrhea, weight loss, leukopenia (P < 0.001), and an 85% mortality, compared with regular diet animals, who had mild diarrhea and weight loss but no leukopenia and a 12% mortality. CONCLUSION: Protein depletion results in increased toxicity to 5-FU, which is associated with a significantly decreased rate of hepatic metabolism and clearance of 5-FU and a significant decrease in hepatic DPD activity. 19F-NMRS can noninvasively identify these alterations of 5-FU metabolism in vivo and may serve as a useful guide to determining chemotherapy dosage adjustments to reduce toxicity.

Animals↗
PubMed1993

Current role of MR imaging in the staging of adenocarcinoma of the prostate.

Surgical cure of adenocarcinoma of the prostate (ACP) is possible in over 80% of cases when the disease is confined to the gland capsule. The endorectal probe for magnetic resonance (MR) imaging has increased resolution of the prostate gland and capsule, which has improved the sensitivity and specificity for staging ACP (.65 sensitivity, .69 specificity for body coil; .87 sensitivity, .85 specificity for the endorectal coil). Normal glandular regions in the peripheral zone and central zone have significantly higher citrate levels than ACP and fibromuscular and fibrous benign prostatic hyperplasia at proton spectroscopy. ACP has a higher phosphomonoester-phosphocreatine ratio than normal glandular tissue at phosphorus spectroscopy. The combination of endorectal coil MR imaging for local spread, and body coil MR imaging for advanced disease, makes MR imaging the premier imaging modality for the preoperative staging of ACP.

Adenocarcinoma↗
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↗