Biomedical subjects

Thomas H Helbich

Publications and source records attributed to Thomas H Helbich.

At least 19 recordsLinked to original sources

PubMed2006

Validation of image quality in full-field digital mammography: is the replacement of wet by dry laser printers justified?

OBJECTIVE: Dry laser printers have replaced wet laser printers to produce hard copies of high-resolution digital images, primarily because of environmental concerns. However, no scientific research data have been published that compare the image quality of dry and wet laser printers in full-field digital mammography (FFDM). This study questions the image quality of these printers. MATERIALS AND METHODS: Objective image quality parameters of both printers were evaluated using a standardized printer test image, i.e., optical density and detectability of specific image elements (lines, curves, and shapes). Furthermore, mammograms of 129 patients with different breast tissue composition patterns were imaged with both printers. A total of 1806 subjective image quality parameters (brightness, contrast, and detail detection of anatomic structures), the detectability of breast lesions, as well as diagnostic performance according to the BI-RADS classification were evaluated. In addition, the presence of film artifacts was investigated. RESULTS: Optical density values were equal for the dry and the wet laser printer. Detection of specific image elements on the printer test image was not different. Ratings of subjective image quality parameters were equal, as were the detectability of breast lesions and the diagnostic performance. Dry laser printer images showed more artifacts (164 versus 27). However, these artifacts did not influence image quality. CONCLUSION: Based on the evidence of objective and subjective parameters, a dry laser printer equals the image quality of a wet laser printer in FFDM. Therefore, not only for reasons of environmental preference, the replacement of wet laser printers by dry laser printers in FFDM is justified.

Adult↗

PubMed2006

Preoperative core needle biopsy does not increase local recurrence rate in breast cancer patients.

OBJECTIVE: Several case reports and clinical studies in the literature demonstrate needle track seeding after core needle biopsy in patients with breast cancer in up to 50% of cases. The impact of this observation on local recurrence and overall survival rate is, however, not fully investigated. PATIENTS AND DESIGN: We retrospectively analysed 719 patients after breast conserving surgery and postoperative radiotherapy for stage I and II breast cancer. We divided this group into patients with (189) and without (530) preoperative core needle biopsy. Demographic data, local recurrence and overall survival rate were compared between these two groups. RESULT: Preoperative core needle biopsy did not significantly influence the local free recurrence rate (median follow-up time of 78 and 71 months, respectively). The prognostic factors and the postoperative therapy did not differ significantly between the two groups. CONCLUSION: Preoperative core needle biopsy seems to have no detrimental impact on local recurrence and overall survival after breast conserving surgery and postoperative radiotherapy.

Aged↗

PubMed2006

MRI-Guided percutaneous biopsy of breast lesions: materials, techniques, success rates, and management in patients with suspected radiologic-pathologic mismatch.

MR imaging of the breast allows the detection of suspicious breast lesions that are occult at mammography and ultrasound. For the histologic verification of such lesions, percutaneous MR imaging-guided biopsy techniques can now be offered as an alternative to open breast biopsy. This review focuses on the currently available devices and techniques for MR imaging-guided percutaneous breast biopsy and reports their achievable diagnostic accuracy. Technical success rates and strategies for patient management are also outlined. In addition, new developments in MR imaging-guided minimally invasive therapeutic interventions are discussed, as well as the potential for research opportunities and directions.

Biopsy↗

PubMed2006

Axillary lymph node metastases in patients with breast carcinomas: assessment with nonenhanced versus uspio-enhanced MR imaging.

PURPOSE: To prospectively assess the accuracy of nonenhanced versus ultrasmall superparamagnetic iron oxide (USPIO)-enhanced magnetic resonance (MR) imaging for depiction of axillary lymph node metastases in patients with breast carcinoma, with histopathologic findings as reference standard. MATERIALS AND METHODS: The study was approved by the university ethics committee; written informed consent was obtained. Twenty-two women (mean age, 60 years; range, 40-79 years) with breast carcinomas underwent nonenhanced and USPIO-enhanced (2.6 mg of iron per kilogram of body weight intravenously administered) transverse T1-weighted and transverse and sagittal T2-weighted and T2*-weighted MR imaging in adducted and elevated arm positions. Two experienced radiologists, blinded to the histopathologic findings, analyzed images of axillary lymph nodes with regard to size, morphologic features, and USPIO uptake. A third independent radiologist served as a tiebreaker if consensus between two readers could not be reached. Visual and quantitative analyses of MR images were performed. Sensitivity, specificity, and accuracy values were calculated. To assess the effect of USPIO after administration, signal-to-noise ratio (SNR) changes were statistically analyzed with repeated-measurements analysis of variance (mixed model) for MR sequences. RESULTS: At nonenhanced MR imaging, of 133 lymph nodes, six were rated as true-positive, 99 as true-negative, 23 as false-positive, and five as false-negative. At USPIO-enhanced MR imaging, 11 lymph nodes were rated as true-positive, 120 as true-negative, two as false-positive, and none as false-negative. In two metastatic lymph nodes in two patients with more than one metastatic lymph node, a consensus was not reached. USPIO-enhanced MR imaging revealed a node-by-node sensitivity, specificity, and accuracy of 100%, 98%, and 98%, respectively. At USPIO-enhanced MR imaging, no metastatic lymph nodes were missed on a patient-by-patient basis. Significant interactions indicating differences in the decrease of SNR values for metastatic and nonmetastatic lymph nodes were found for all sequences (P < .001 to P = .022). CONCLUSION: USPIO-enhanced MR imaging appears valuable for assessment of axillary lymph node metastases in patients with breast carcinomas and is superior to nonenhanced MR imaging.

Adult↗

PubMed2006

Image quality of a wet laser printer versus a paper printer for full-field digital mammograms.

OBJECTIVE: The purpose of our study was to compare the image quality of a wet laser printer with that of a paper printer for full-field digital mammography (FFDM). MATERIALS AND METHODS: For both a wet laser printer and a paper printer connected to an FFDM system, image quality parameters were evaluated using a standardized printer test image (luminance density, dynamic range). The detectability of standardized objects on a phantom was also evaluated. Furthermore, 640 mammograms of 80 patients with different breast tissue composition patterns were imaged with both printers. Subjective image quality parameters (brightness, contrast, and detection of details of anatomic structures-that is, skin, subcutis, musculature, glandular tissue, and fat), the detectability of breast lesions (mass, calcifications), and the diagnostic performance according to the BI-RADS classification were evaluated. RESULTS: Both the luminance density and the dynamic range were superior for the wet laser printer. More standardized objects were visible on the phantom imaged with the wet laser printer than with the paper printer (13/16 vs 11/16). Each subjective image quality parameter of the mammograms from the wet laser printer was rated superior to those of the paper printer. Significantly more breast lesions were detected on the wet laser printer images than on the paper printer images (masses, 13 vs 10; calcifications, 65 vs 48; p < 0.05). With the paper printer images, BI-RADS 4 and 5 categories were underestimated for 10 (43.5%) of 23 patients. CONCLUSION: For FFDM, images obtained from a wet laser printer show superior objective and subjective image quality compared with a paper printer. As a consequence, the paper printer should not be used for FFDM.

Adult↗

PubMed2005

Lesion miss rates and false-negative rates for 1115 consecutive cases of stereotactically guided needle-localized open breast biopsy with long-term follow-up.

PURPOSE: To retrospectively determine the lesion miss rate and false-negative rate of needle-localized open breast biopsy (NLOBB) with stereotactic guidance in a large study population. MATERIALS AND METHODS: The ethical review board approved the study; the need for informed consent was waived. A total of 1115 stereotactic NLOBBs performed in 1068 women aged 22-90 years (mean age, 54 years) were tracked to determine outcomes. In cases of malignancy, NLOBB was considered to be diagnostically successful. The mammographic outcomes in all patients with benign results at NLOBB were tracked for at least 2 years. Cases without such mammographic follow-up were cross-referenced with a tumor registry after at least 54 months. The lesion miss rate was based on all malignant lesions and all lesions with long-term mammographic follow-up. Results from all 1115 NLOBBs were used to report the false-negative rate. RESULTS: Of 1115 NLOBBs, 472 (42%) had malignant results. Mammographic follow-up data were available for 535 (83%) of 643 NLOBBs with benign results. Mammographic follow-up revealed 11 lesions that were missed with NLOBB, of which five were malignant and six benign. Thus, the lesion miss rate with NLOBB was 1.1% (11/[472 + 535]). Among the 643 cases, in 108 of them without mammographic follow-up (17%), cross-referencing with a tumor registry did not reveal missed cases of breast carcinoma. The false-negative rate was therefore 1.0% (5/[472 + 5]). CONCLUSION: On the basis of the results of long-term follow-up, the authors noted a lesion miss rate of 1.1% and a false-negative rate of 1.0%, which indicate that NLOBB with stereotactic guidance is an accurate method for diagnosing breast lesions.

Adult↗

PubMed2005

Unenhanced multi-detector row CT in patients suspected of having urinary stone disease: effect of section width on diagnosis.

PURPOSE: To assess prospectively the effect of section width in multi-detector row computed tomographic (CT) evaluation of patients with acute flank pain who are suspected of having or known to have urinary stone disease. MATERIALS AND METHODS: This study was approved by the ethics committee of the authors' university, and written informed consent was obtained from all patients. One hundred forty-seven patients (age range, 11-101 years; mean, 51.4 years +/- 18.7 [standard deviation]) suspected of having urinary stone disease underwent unenhanced multi-detector row CT. CT was performed with four detector rows, a section thickness of 1.0 mm, an effective tube current-time product of 100 mAs, and a tube voltage of 120 kVp (CT dose index, 11.4 mGy). From these data, three sets of transverse images were reconstructed with section widths of 1.5, 3.0, and 5.0 mm and approximately 50% of overlap each. Scans were evaluated in varying random orders by two radiologists for the number, size, and location of uroliths and nephroliths and for the presence of phleboliths, renal cysts, and secondary signs of obstruction. The significance of differences between the numbers of detected calcifications and the numbers of associated abnormalities on the scans obtained with varying section widths was tested with the McNemar test at a P level of less than .05. Spearman rho rank correlation coefficients were calculated to assess the correlation between the presence of uroliths and the presence of secondary signs. RESULTS: Uroliths were found in 72 of 147 (49.0%) patients, and nephroliths were found in 16 patients (10.9%). There was no significant difference between section widths of 1.5 and 3.0 mm with regard to the number of detected stones (264 uroliths and 61 nephroliths for both protocols). Transverse sections 5.0-mm wide revealed significantly fewer uroliths (n = 231; P < .001) and nephroliths (n = 47; P < .016). The final diagnosis was changed in four of 72 patients. All missed renal and ureteral stones measured less than 3 mm in diameter. CONCLUSION: Overlapping 3-mm sections are sufficient for the detection of urinary stone disease. Small calculi (<3 mm) may be missed on 5.0-mm-thick sections.

Adolescent↗

PubMed2005

Computer-assisted quantitative assessment of power Doppler US: effects of microbubble contrast agent in the differentiation of breast tumors.

RATIONALE AND OBJECTIVES: To objectively quantify the effects of a microbubble contrast agent to differentiate breast tumors with power doppler ultrasound and to compare these results with color doppler ultrasound (CD US). METHODS: In 47 patients a microbubble contrast agent was injected intravenously. Computer-assisted quantitative assessment of the color pixel density was performed to evaluate the increase in Doppler signals. Results were compared to previously published results of a color Doppler ultrasound study. RESULTS: Peak color pixel density at contrast-enhanced power Doppler ultrasound was higher for carcinomas than for benign tumors (P < 0.03). Time to peak enhancement was shorter in carcinomas than in benign tumors (P < 0.01). For both parameters, diagnostic accuracy of power Doppler ultrasound was 69 and 78%, and for color Doppler ultrasound 62 and 76%, respectively. CONCLUSIONS: Quantitative assessment of contrast-enhanced power Doppler ultrasound showed significant differences in malignant and benign breast tumors. Diagnostic accuracy of contrast-enhanced power Doppler ultrasound was higher compared to color Doppler ultrasound.

Adult↗

PubMed2005

Potential of dose reduction after marker placement with full-field digital mammography.

OBJECTIVES: The purpose of our study was to assess the potential for radiation dose reduction in digital postinterventional digital mammograms after marker placement. MATERIALS AND METHODS: One hundred consecutive cases of marker placement (hook-wire localization or postbiopsy clip marker placement), with 200 full-field digital baseline mammograms (craniocaudal and mediolateral), were included in this prospective trial. For the postinterventional digital mammograms, the milliampere seconds were reduced either by 50% or by 75%. Dose-reduced images were evaluated for sufficient image quality to verify the position of the marker. RESULTS: In 193 of 200 cases (96.5%), image quality was sufficient to verify the correct position of the marker. One (1%) case with insufficient image quality occurred in the 50% dose-reduction group and 6 (6%) in the 75% dose-reduction group (P = 0.06). CONCLUSION: Our results indicate that under evaluation of each individual case, a dose reduction of 50% to 75% can be recommended in postinterventional digital mammograms.

Breast Neoplasms↗

PubMed2005

Characterization of benign and malignant breast lesions with computed tomography laser mammography (CTLM): initial experience.

OBJECTIVES: The aim of this study was to characterize benign and malignant breast lesions with computed tomography-laser mammography (CTLM). MATERIALS AND METHODS: In a prospective study, 100 female patients with 105 breast lesions classified as BIRADS IV to V at mammography underwent mammography, CTLM, and histologic verification at our institution. CTLM images were analyzed by radiologists with knowledge of the lesion's position but who were blinded to histology and morphologic findings from mammography. Two radiologists independently evaluated whether there was increased absorption, a sign of malignancy, on CTLM and assessed the appearance (volumes or linear branching) and shape (round or irregular) of the lesions. RESULTS: Histologic analysis revealed 55 benign (52.4%) and 50 malignant (47.6%) breast lesions. Increased absorption was observed significantly more often in malignant than in benign lesions (70.0% vs. 32.7%, P = 0.028). Invasive cancer showed increased absorption in 76.2%, and ductal carcinoma in situ in 37.5%. Common morphologic characteristics of increased absorption were "volumes" (85.7% of malignant and 77.8% of benign lesions) with round shape (78.1% of malignant and 73.3% of benign lesions). CONCLUSION: Our data indicate that CTLM, when used as an adjunct to mammography, may provide additional information to characterize benign and malignant breast lesions.

Adolescent↗

PubMed2005

The negative predictive value of electrical impedance scanning in BI-RADS category IV breast lesions.

OBJECTIVES: We sought to prospectively assess the value of electrical impedance scanning (EIS) in discriminating benign from malignant lesions classified as BI-RADS category IV in mammography in comparison with ultrasound (US), with a special focus on negative prediction. MATERIALS AND METHODS: EIS was performed on 128 BI-RADS category IV lesions in 121 women (mean, 51.8 years). The newly developed EIS software 2.67 calculates a BI-RADS-like level of suspicion (LOS) on a 5-grade scale. LOS 1, 2, and 3 were considered negative; LOS 4 and 5 were considered positive. Histopathologic results were obtained in all lesions. RESULTS: Histology proved 37 lesions malignant, 91 benign. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of EIS compared with US were 94.6%, 74.7%, 80.5%, 60.3%, 97.1% versus 90.5%, 33.8%, 47.2%, 29.7%, 92.0%, respectively. In 43 lesions sized < or = 10 mm, EIS demonstrated better sensitivity, specificity, accuracy, PPV, and NPV of 100%, 83.3%, 90.7%, 82.6%, and 100%, respectively. Although NPV was also high, US showed no sufficient results in 39 (30.5%) lesions because of microcalcifications. Receiver operating curve analysis revealed best results for a combined use of US and EIS. CONCLUSIONS: With a NPV of 97.1% of EIS in BI-RADS category IV breast lesions, a negative result in these lesions could be firm indication to manage them as BI-RADS-category III and refer patients for a 6-month short-interval follow-up rather than performing a biopsy. The best adjunctive diagnostic performance can be achieved by a combination of US and EIS. Costs and patient morbidity could be minimized.

Breast↗

PubMed2004

Follow-up of palpable circumscribed noncalcified solid breast masses at mammography and US: can biopsy be averted?

PURPOSE: To determine whether palpable noncalcified solid breast masses with benign morphology at mammography and ultrasonography (US) can be managed similarly to nonpalpable probably benign lesions (Breast Imaging Reporting and Data System [BI-RADS] category 3)-that is, with periodic imaging surveillance-and to determine whether biopsy can be averted in these lesions. MATERIALS AND METHODS: No institutional review board approval or patient consent was required. This retrospective analysis, based on final imaging reports, included 152 patients (age range, 28-77 years; mean age, 48.3 years) with 157 palpable noncalcified solid masses that were classified as probably benign at initial mammography and US. Of 152 patients, 108 underwent follow-up with mammography and US (6-month intervals for 2 years, then 12-month intervals). The remaining 44 patients underwent surgical or needle biopsy after initial imaging. Lesions were analyzed at initial and follow-up examinations. Statistical analysis included Student t test and corresponding exact 95% confidence intervals. RESULTS: In 108 patients who underwent follow-up only, 112 lesions were palpable. In 102 (94.4%) of 108 patients, masses remained stable during follow-up. Lesions were followed for at least 2 years (mean, 4.1 years; range, 2-7 years). In six (5.6%) patients, palpable lesions increased in size during follow-up; these lesions were benign at subsequent open biopsy. No breast carcinoma was diagnosed in the 44 patients with 45 palpable lesions who underwent biopsy after initial imaging. Of 157 lesions, no malignant tumors were observed (exact one-sided 95% confidence interval: 0%, 1.95%). CONCLUSION: The data strongly suggest that palpable noncalcified solid breast masses with benign morphology at mammography and US can be managed similarly to nonpalpable BI-RADS category 3 lesions, with short-term follow-up (6-month intervals for 2 years). More data, based on a larger series, are required to determine whether this conclusion is correct.

Adult↗

PubMed2004

Stereotactic 11-gauge vacuum-assisted breast biopsy: influence of number of specimens on diagnostic accuracy.

PURPOSE: To determine whether number of specimens obtained at stereotactic 11-gauge vacuum-assisted breast biopsy with the patient prone influences diagnostic accuracy and to determine whether this number varies depending on mammographic appearance of lesions as masses or microcalcifications. MATERIALS AND METHODS: Biopsy was prospectively performed in 100 patients (median age, 55 years; range, 31-81 years) with 100 lesions that were mammographically evident as masses (n = 50) and microcalcifications (n = 50) with standardized protocol to acquire 20 specimens per lesion in three 360 degrees probe rotations at one skin entry site. Specimens were histologically evaluated sequentially, and findings were compared with results of surgical excision or of mammographic follow-up for at least 24 months. Differences in diagnostic yield after each probe rotation and differences in diagnostic yield between masses and microcalcifications were determined with chi(2) test. RESULTS: Up to 12 specimens harvested within two 360 degrees probe rotations were necessary to yield correct diagnosis in 96% of patients with masses and 92% of patients with microcalcifications. Diagnostic yield was not improved with more than 12 specimens for masses or microcalcifications. In two (4%) of 47 patients with lesions that were eventually diagnosed as cancer, results at stereotactic biopsy indicated they were benign. Underestimation of diagnosis of lesions as atypical ductal hyperplasia and ductal carcinoma in situ occurred in two (50%) of four and two (17%) of 12 lesions, respectively. With 20 specimens harvested during three probe rotations, there was no statistically significant difference in diagnostic yield between patients with masses and those with microcalcifications (P =.68). CONCLUSION: At 11-gauge vacuum-assisted biopsy, highest diagnostic yield was achieved with 12 specimens per lesion, independent of mammographic appearance of the lesion. Even with standardized retrieval of 20 specimens per lesion, underestimation of disease still occurs.

Adult↗

PubMed2003

Quantification of breast tumor microvascular permeability with feruglose-enhanced MR imaging: initial phase II multicenter trial.

PURPOSE: To investigate use of the macromolecular contrast agent feruglose for differentiating and grading of human benign and malignant breast tumors on the basis of their microvascular characteristics. MATERIALS AND METHODS: Sixty-three women with 63 primary breast lesions were examined with dynamic T1-weighted gradient-echo magnetic resonance (MR) imaging after intravenous injection of feruglose. A two-compartment unidirectional kinetic model applied to the dynamic data yielded estimates of the endothelial transfer coefficient, KPS, and the fractional plasma volume of the tumors. These MR imaging-derived parameters were correlated with the histologic tumor grade and quantified according to the Scarff-Bloom-Richardson (SBR) score by means of Pearson product moment correlation analyses. Differences between malignant and nonmalignant breast lesions with respect to KPS for feruglose were evaluated by means of the chi2 test and by calculating the sensitivity, specificity, and positive and negative predictive values. RESULTS: Histologic analysis revealed 26 benign and 37 malignant tumors. A moderate yet statistically significant correlation between KPS and SBR score was found (R = 0.496, P <.001). No significant correlation was observed between fractional plasma volume and SBR score (R = 0.085, P =.507). The KPS values were zero for 19 (73%) of the 26 benign tumors and were greater than zero for 27 (73%) of the 37 carcinomas. This distribution was significantly different (chi2 = 13.035, P =.001). With the criterion KPS > 0 in carcinomas, sensitivity was 0.73, specificity was 0.73, and the positive predictive value was 0.79. CONCLUSION: Quantitative measures of tumor microvascular permeability can be used for breast tumor characterization. The probability of breast tumor microvascular hyperpermeability to be associated with malignancy is 79%.

Adult↗

PubMed2003

Using a dedicated lung-marker system for localization of pulmonary nodules before thoracoscopic surgery.

OBJECTIVE: Our aim was to evaluate the effectiveness of a commercially available dedicated lung-marker system for localization of pulmonary nodules before video-assisted thoracoscopic surgery. SUBJECTS AND METHODS: Guidewires were positioned under CT fluoroscopy guidance in 16 patients (11 men, five women; age range, 39-79 years; mean age, 60.4 years). We measured the size of the targeted nodule, its distance to the closest pleural surface, the angle between the introducer needle and the chest wall, and the time for performance of the procedure in each patient. Note was made of any complications after guidewire placement. RESULTS: In the 16 patients, the average nodule size was 6.7 mm (range, 3-12 mm), the average distance to the pleural surface was 10.6 mm (range, 3-22 mm), and the average pleural puncture angle was 59 degrees (range, 25-78 degrees). The marking procedure was completed within an average of 9.5 min (range, 7-15 min). Small pneumothoraces occurred in five (31.3%) of 16 patients. In 15 (93.8%) of 16 patients, thoracoscopic resection of the targeted nodule was successful; in one patient with dyspnea (6.3%), inaccurate localization resulting in an open thoracotomy occurred because an intervening fissure was not visualized. Dislodgement of the guidewire into the pleural space occurred in one patient (6.3%). CONCLUSION: The dedicated lung-marker system is a fast and effective method for localization of pulmonary nodules before thoracoscopic resection.

Adult↗

PubMed2003

[Diagnostic management of nipple discharge].

Nipple discharge may be a symptom of a variety of diseases. The importance of nipple discharge is its possible association with breast carcinoma. Not only the precise clinical evaluation but also particularly imaging evaluation by mammography, ultrasound, galactography or MR-galactography is necessary to establish the exact diagnosis and plan proper treatment. Depending on the underlying pathology--most commonly intraductal papilloma, fibrocystic changes or breast carcinoma--the optimal therapeutic regimen, such as single lactiferous duct excision on the one end and modified radical mastectomy on the other end of the spectra may be chosen.

Breast Cyst↗

PubMed2003

[Factors influencing quality of mammograms].

Due to its outstanding role for screening and diagnosis of breast cancer, optimizing the quality of mammographies was in the main focus of interest within the past two decades. However, there exist additional, non-technical factors influencing diagnostic confidence of mammograms, which were usually not part of discussions concerning mammographic image quality. Nevertheless, these non-technical factors are of great interest into the female population. Information and instruction of the patient prior to mammography helps to increase the compliance of the patient during mammography, and thus not only cooperation during examination is optimized, but also cooperation in the screening program. Furthermore, timing the examination within the first part of the menstrual cycle and regarding specific patient-related factors can decrease pain and discomfort during mammography, which will increase image quality.

Austria↗

PubMed2002

Dynamic contrast-enhanced magnetic resonance imaging as a surrogate marker of tumor response to anti-angiogenic therapy in a xenograft model of glioblastoma multiforme.

PURPOSE: To evaluate the effects of a neutralizing anti-vascular endothelial growth factor (anti-VEGF) antibody on tumor microvascular permeability, a proposed indicator of angiogenesis, and tumor growth in a rodent malignant glioma model. MATERIALS AND METHODS: A dynamic contrast-enhanced magnetic resonance imaging (MRI) technique, permitting noninvasive in vivo and in situ assessment of potential therapeutic effects, was used to measure tumor microvascular characteristics and volumes. U-87, a cell line derived from a human glioblastoma multiforme, was implanted orthotopically into brains of athymic homozygous nude rats. RESULTS: Treatment with the monoclonal antibody A4.6.1, specific for VEGF, significantly inhibited tumor microvascular permeability (6.1 +/- 3.6 mL min(-1)100 cc(-1)), compared to the control, saline-treated tumors (28.6 +/- 8.6 mL min(-1)100 cc(-1)), and significantly suppressed tumor growth (P <.05). CONCLUSION: Findings demonstrate that tumor vascular permeability and tumor growth can be inhibited by neutralization of endogenous VEGF and suggest that angiogenesis with the maintenance of endothelial hyperpermeability requires the presence of VEGF within the tissue microenvironment. Changes in tumor vessel permeability and tumor volumes as measured by contrast-enhanced MRI provide an assay that could prove useful for clinical monitoring of anti-angiogenic therapies in brain tumors.

Animals↗