Biomedical subjects

Y De Deene

Publications and source records attributed to Y De Deene.

22 records · Page 2Linked to original sources

PubMed1995

Noninvasive MRI thermometry with the proton resonance frequency (PRF) method: in vivo results in human muscle.

The noninvasive thermometry method is based on the temperature dependence of the proton resonance frequency (PRF). High-quality temperature images can be obtained from phase information of standard gradient-echo sequences with an accuracy of 0.2 degrees C in phantoms. This work was focused on the in vivo capabilities of this method. An experimental setup was designed that allows a qualitative in vivo verification. The lower-leg muscles of a volunteer were cooled and afterwards reheated with an external water bolus. The temperature of the bolus water varied between 17 degrees C and 37 degrees C. The in vivo temperature images can be used to extract the temperature in muscle tissue. The data in the fat tissue are difficult to interpret because of the predominance of susceptibility effects. The results confirm the method's potential for hyperthermia control.

Algorithms↗

PubMed1995

Static, dynamic and first-pass MR imaging of musculoskeletal lesions using gadodiamide injection.

Forty-five patients with known or suspected musculoskeletal tumors were examined with static and dynamic MR imaging to evaluate the safety, tolerability and diagnostic utility of gadodiamide injection and to assess the diagnostic value of dynamic MR imaging and parametric "first-pass" (FP) images. The proportion of patients presenting more diagnostic information on the contrast-enhanced compared to the precontrast spin-echo examinations was determined. The dynamic enhancement characteristics were evaluated with time-intensity curves and parametric images of the FP enhancement rate. The tolerance of gadodiamide injection was good. Contrast enhancement was useful for delineating tumor from muscle, and differentiating viable from necrotic tissue and cystic from solid lesions. Malignant tumors showed a significantly higher slope value, earlier onset of enhancement, and higher maximum enhancement than benign lesions. However, slope values could not be used to predict the malignant potential of a lesion, due to overlap between highly vascular benign and low vascular malignant lesions. By displaying highly vascular areas, parametric FP images provided useful information on the most active part in a tumor before biopsy and for assessing the incorporation of bone-chip allografts. Static, dynamic and FP MR imaging using gadodiamide injection appears safe and provides useful information for diagnosis, biopsy and follow-up of musculoskeletal lesions.

Adult↗

PubMed1994

First-pass images of musculoskeletal lesions: a new and useful diagnostic application of dynamic contrast-enhanced MRI.

The purpose of this study was to evaluate the diagnostic value of parametric images which display the first-pass of Gd-DTPA after intravenous bolus injection. Single slice dynamic contrast-enhanced MRI (Turbo-FLASH) with a temporal resolution of 2.41 s was performed in 40 benign and malignant musculoskeletal lesions. Parametric 'first-pass' images were obtained by using a new postprocessing technique, derived from a home written computer program, which calculated the steepest slope of the time-intensity curve pixel by pixel. First-pass images provided qualitative and quantitative information, which was useful for diagnosis and therapy. Demonstration of the areas with the highest vascularization was very helpful in planning the best biopsy site in 6 patients and to delineate tumor from peritumoral muscle edema in 4 patients. In 10 patients the first-pass images provided additional information, which was not visible on the conventional spin-echo images. The most promising application was the ability to evaluate the response to preoperative chemotherapy in a patient with Ewing's sarcoma. Although a highly statistically significant difference (p < 0.001) was found between the first-pass slope values of benign and malignant lesions, the sensitivity (77%) and specificity (71%) of this method were too low to permit a definite differentiation of highly vascular benign from malignant lesions. Pathologic examination of 17 lesions, performed in the plane of the first-pass image, showed a good correlation between the first-pass slope values and the vascularization of the tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1994

Benign and malignant musculoskeletal lesions: dynamic contrast-enhanced MR imaging--parametric "first-pass" images depict tissue vascularization and perfusion.

PURPOSE: To assess the diagnostic value of parametric magnetic resonance images that display the first pass (FP) of gadopentetate dimeglumine. MATERIALS AND METHODS: Dynamic, contrast material-enhanced, fast low-angle shot MR imaging was performed of 100 musculoskeletal lesions in 36 female and 64 male patients (aged 9-81 years [mean, 34 years]). The highest slope value of the time-intensity curve was calculated pixel by pixel and displayed on the FP image, with a gray-scale value equal to the slope value. Tissue vascularization and perfusion were evaluated at pathologic and angiographic examinations in 33 lesions. RESULTS: A significant difference (P < .001) was found between the FP slope values of benign (mean, 36.2% per second) and malignant (mean, 67.4% per second) lesions. FP images depicted tissue vascularization and perfusion rather than benignity or malignancy, because there is an overlap in the slope values of highly vascular benign lesions and malignant lesions. CONCLUSION: FP images provide diagnostically useful information by depicting tissue vascularization and perfusion.

Adolescent↗