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J O Barentsz

Publications and source records attributed to J O Barentsz.

At least 19 recordsLinked to original sources
PubMed2007

Prediction of chemotherapeutic response of colorectal liver metastases with dynamic gadolinium-DTPA-enhanced MRI and localized 19F MRS pharmacokinetic studies of 5-fluorouracil.

Systemic chemotherapy is effective in only a subset of patients with metastasized colorectal cancer. Therefore, early selection of patients who are most likely to benefit from chemotherapy is desirable. Response to treatment may be determined by the delivery of the drug to the tumor, retention of the drug in the tumor and by the amount of intracellular uptake, metabolic activation and catabolism, as well as other factors. The first aim of this study was to investigate the predictive value of DCE-MRI with the contrast agent Gd-DTPA for tumor response to first-line chemotherapy in patients with liver metastases of colorectal cancer. The second aim was to investigate the predictive value of 5-fluorouracil (FU) uptake, retention and catabolism as measured by localized (19)F MRS for tumor response to FU therapy. Since FU uptake, retention and metabolism may depend on tumor vascularization, the relationship between (19)F MRS and the DCE-MRI parameters k(ep), K(trans) and v(e) was also examined (1). In this study, 37 patients were included. The kinetic parameters of DCE-MRI, k(ep), K(trans) and v(e), before start of treatment did not predict tumor response after 2 months, suggesting that the delivery of chemotherapy by tumor vasculature is not a major factor determining response in first-line treatment. No evident correlations between (19)F MRS parameters and tumor response were found. This suggests that in liver metastases that are not selected on the basis of their tumor diameter, FU uptake and catabolism are not limiting factors for response. The transfer constant K(trans), as measured by DCE-MRI before start of treatment, was negatively correlated with FU half-life in the liver metastases, which suggests that, in metastases with a larger tumor blood flow or permeability surface area product, FU is rapidly washed out from the tumor.

Adult↗
PubMed2006

Evaluation of chemotherapy with magnetic resonance imaging in patients with regionally metastatic or unresectable bladder cancer.

OBJECTIVES: To determine whether the failure of chemotherapy in patients with regionally metastatic or unresectable transitional cell carcinoma (TCC) of the bladder can be predicted early in the course of chemotherapy with magnetic resonance (MR) imaging. METHODS: In this prospective study, 36 patients with regionally metastatic or unresectable TCC of the urinary bladder underwent MR imaging before and after two, four, and six cycles of chemotherapy with Methotrexate, Vinblastine, Adriamycin (doxorubicin) and Cisplatin (MVAC). The response after two cycles of MVAC was evaluated by using conventional tumour size parameters with unenhanced MR imaging and with changes in the time to the start of tumour or lymph node enhanced at fast dynamic contrast-enhanced MR imaging. The results obtained with these techniques were compared with the findings at histopathology in cystectomy or transurethral resection specimens that were obtained after chemotherapy. Duration of survival was defined as the time from the start of chemotherapy until disease-specific death. Kaplan-Meier curves were drawn to determine the difference in prognosis between responders and nonresponders. RESULTS: After two cycles of chemotherapy, the accuracy, sensitivity, and specificity in distinguishing responders from nonresponders with conventional MR imaging were 69%, 81%, and 50%, respectively. With the fast dynamic contrast-enhanced technique, accuracy, sensitivity, and specificity were 92%, 91%, and 93% respectively. The median bladder cancer specific survival was 28 months for all patients studied. Responders to chemotherapy at fast dynamic contrast-enhanced MR had better median disease-specific survival than nonresponders (42 months vs. 12 months [p<0.0001]). CONCLUSION: We can predict whether a patient will respond to chemotherapy after two cycles of chemotherapy with fast dynamic contrast-enhanced MR imaging.

Adult↗
PubMed2003

Magnetic resonance imaging of the main pulmonary artery: reliable assessment of dimensions in Marfan patients on a simple axial spin echo image.

OBJECTIVE: To investigate if a simple axial spin echo (SE) image can be used for reliable assessment of pulmonary artery dimensions in patients with Marfan syndrome. METHODS: Fifty Marfan patients (mean age 33 +/- 10 years; 34 men, 16 women) and 15 normal subjects (mean age 28 +/- 4 years; nine men, six women) underwent cardiac magnetic resonance imaging (MRI). Pulmonary artery dimensions were obtained on axial SE images at two different levels: (1) the level of the pulmonary artery root, and (2) the level of the pulmonary artery bifurcation. To evaluate the accuracy of axial plane measurements 10 Marfan patients also underwent contrast-enhanced MR angiography (CE-MRA). RESULTS: In the 10 Marfan patients who also underwent CE-MRA, the mean diameter at the pulmonary bifurcation assessed with CE-MRA (31.5 +/- 3.6 mm) was almost equal to mean diameter assessed with axial SE (30.7 +/- 3.6 mm). Agreement of methodology according to Bland and Altman analysis showed a 95% confidence interval ranging from -2.6 to + 4.4 mm for all distances of the pulmonary artery root. In Marfan patients the mean right-left diameter measured on both axial SE images and CE-MRA was approximately 2.5 mm larger than the anterior-right and anterior-left diameters (p < 0.001). CONCLUSIONS: Axial SE MRI is a reliable and easy acquisition to measure pulmonary artery dimensions in patients with Marfan syndrome, and could be used for follow-up, especially in patients with severe involvement of the cardiovascular system. Not only the pulmonary artery trunk but also the asymmetric pulmonary root should be measured, although the clinical relevance of the asymmetric root is not yet known.

Adult↗
PubMed2003

Mycotic aneurysm of the popliteal artery as a complication of intravesical BCG therapy for superficial bladder cancer. Case report and literature review.

A 67-year-old man was treated with maintenance intravesical BCG for superficial bladder cancer. As a culture-proven complication of this therapy, he developed general malaise, high fever, granulomatous hepatitis and a mycotic aneurysm in his left knee. All complications were treated successfully with antituberculous therapy. No vascular surgery was necessary. This case report again stresses the necessity to recognise complications of BCG treatment and to start adequate therapy as soon as possible.

Adjuvants, Immunologic↗
PubMed2001

Characterization of low-intensity lesions in the peripheral zone of prostate on pre-biopsy endorectal coil MR imaging.

The aim of this study was to determine which morphological features of low-intensity lesions in the peripheral zone of the prostate are predictable of prostate cancer on pre-biopsy T2-weighted integrated endorectal phased-array MR images. The MR examinations were performed in 69 consecutive patients with elevated level of prostate-specific antigen (>4 ng/ml) and/or a positive digital rectal examination before transperineal 12-site biopsy. Two radiologists evaluated presence of lesions, their morphological features, and possibility of malignancy in divided into four sections of the peripheral zone. Imaging analysis findings were compared with biopsy results. Discriminative features were selected by stepwise logistic regression. Descriptive statistics and receiver operating characteristics (ROC) curves were also calculated. Sixty-eight benign lesions and 23 malignant lesions were found. Wedge shape and diffuse extensions without mass effect were significantly associated with benignity ( P=0.0105 and 0.002, respectively). Lesion size was significantly associated with malignancy ( P=0.0001). For evaluating probability of malignancy for lesions, regression model showed a comparable accuracy with the total impression for the readers in ROC analysis (Az 0.9095 vs 0.9266, respectively). Wedge shape, diffuse extension without mass effect, and size are the morphological features of low-intensity lesions in the peripheral zone on pre-biopsy T2-weighted MR images that give the best prediction of malignancy.

Aged↗
PubMed2001

Magnetic resonance imaging and mammography in women with a hereditary risk of breast cancer.

BACKGROUND: Although breast cancer screening is recommended to start at a younger age for women with a hereditary risk of breast cancer, the sensitivity of mammography for these women is reduced. We compared magnetic resonance imaging (MRI) with mammography to determine which is more sensitive and whether MRI could play a role in the early detection of breast cancer for these women. METHODS: We constructed a retrospective cohort of all breast MRI and mammography surveillance reports made in our department from November 1994 to February 2001. All of the 179 women in the cohort had received biannual palpation in addition to annual imaging by MRI, mammography, or both. The 258 MRI images and the 262 mammograms were classified with the use of the BI-RADS (i.e., Breast Imaging Reporting and Data System) scoring system, which has five categories to indicate the level of suspicion of a lesion. Receiver operator characteristic curves were generated for MRI and mammography, and the area under each curve (AUC) was assessed for the entire cohort of 179 women and for a subset of 75 women who had received both an MRI and a mammographic examination within a 4-month period. All statistical tests were two-sided. RESULTS: In the cohort of 179 women, we detected 13 breast cancers. Seven cancers were not revealed by mammography, but all were detected by MRI. For the entire cohort, the AUC for mammography was 0.74 (95% confidence interval [CI] = 0.68 to 0.79), and the AUC for MRI was 0.99 (95% CI = 0.98 to 1.0). For the subset of women who had both examinations, the AUC for mammography was 0.70 (95% CI = 0.60 to 0.80), and the AUC for MRI was 0.98 (95% CI = 0.95 to 1.0). CONCLUSION: MRI was more accurate than mammography in annual breast cancer surveillance of women with a hereditary risk of breast cancer. Larger prospective studies to examine the role of MRI in screening programs are justified.

Adult↗
PubMed2001

Post-radiotherapy contrast enhancement changes in fast dynamic MRI of cervical carcinoma.

This pilot study determines fast dynamic gadolinium enhanced MRI contrast enhancement parameters (onset of enhancement and time to peak enhancement) before and after radiotherapy in 10 cervical carcinoma patients. Before radiotherapy, onset of enhancement and time to peak enhancement were early, with a median of 4.5 and 5.2 seconds, respectively. High-grade tumors showed early enhancement, compared with low-grade. After radiotherapy, contrast enhancement patterns differed. In survivors, onset of enhancement after radiotherapy was later than before radiotherapy. In non-survivors, onset of enhancement after radiotherapy was still early. The median difference in onset of enhancement before and after radiotherapy in survivors and non-survivors was an increase of 3.2 and a decrease of 1.1 seconds, respectively. Early onset of enhancement after radiotherapy was a better predictor for survival than a high-signal intensity zone on post radiotherapy unenhanced T1/T2-weighted MRI. It is concluded that enhancement parameters from fast dynamic Gd-enhanced MR images can provide additional functional information with regard to tumor vascularization, and may have prognostic significance. It complements clinical examination and unenhanced MRI in determining the effectiveness of radiotherapy treatment in cervical carcinoma. Future studies will focus on the clinical utility and improvements of the estimation of contrast-enhanced parameters with this new technique.

Contrast Media↗
PubMed2001

Accurate estimation of pharmacokinetic contrast-enhanced dynamic MRI parameters of the prostate.

Quantitative analysis of contrast-enhanced dynamic MR images has potential for diagnosing prostate cancer. Contemporary fast acquisition techniques can give sufficiently high temporal resolution to sample the fast dynamics observed in the prostate. Data reduction for parametric visualization requires automatic curve fitting to a pharmacokinetic model, which to date has been performed using least-squares error minimization methods. We observed that these methods often produce unexpectedly noisy estimates, especially for the typically fast, intermediate parameters time-to-peak and start-of-enhancement, resulting in inaccurate pharmacokinetic parameter estimates. We developed a new curve fit method that focuses on the most probable slope. A set of 10 patients annotated using histopathology was used to compare the conventional and new methods. The results show that our new method is significantly more accurate, especially in the relatively less-enhancing peripheral zone. We conclude that estimation accuracy depends on the curve fit method, which is especially important when evaluating the peripheral zone of the prostate.

Aged↗
PubMed2000

Preoperative MRA assessment of the coronary arteries in an ascending aortic aneurysm.

We present a patient with an aneurysm that included both the aortic root and the ascending aorta. Visualization of the coronary arteries by x-ray angiography was not technically feasible. Magnetic resonance angiography (MRA) was thus performed and allowed an accurate evaluation of the involvement of the coronary arteries in the aneurysm and the patency of the proximal coronaries, as well as visualization of the aneurysm itself.

Adult↗
PubMed2000

Correlation of high-resolution breast MR imaging with histopathology; validation of a technique.

A high-resolution three-dimensional surface gradient coil set was used to obtain magnetic resonance (MR) images of breast specimens, using a gradient-echo pulse sequence (TR/TE 1000/8 msec, flip angle 75 degrees), with 117 micrometer in-plane resolution and 1 mm slice thickness. Breast tissues were obtained from one autopsy and three surgical specimens. High-resolution breast MR images and histopathology sections (7 micrometer thickness) were acquired in the same anatomical plane. Radiographs were acquired of the sliced specimens (approximately 5 mm thick) so that images from all three methods could be correlated. It was found that in vitro high-resolution breast MRI correlated well with low-resolution microscopic histology, demonstrating normal anatomy (lobules, ducts, connective tissue strands, blood vessels) and pathology (tumor content, margins, and presence of microcalcifications) of the breast more clearly than conventional pre-gadolinium breast MRI. High-resolution breast MRI may improve specificity, when added to a conventional breast MRI protocol.

Biopsy↗
PubMed2000

The role of MR imaging in invasive cervical carcinoma.

In this article the role of MR imaging in the management of cervical cancer is reviewed and illustrated. The appearance of the normal uterine cervix and of cervical carcinoma is shown. Important factors for optimal MR imaging of cervical carcinoma are reviewed. The value of MR imaging in the staging of cervical carcinoma is illustrated by showing parametrial invasion and lymph node involvement. Finally, the value of MR imaging staging is compared with clinical staging, CT staging, and surgical findings. The role of new imaging techniques, such as fast dynamic enhanced MR imaging, is described.

Cervix Uteri↗
PubMed2000

Prostate cancer staging: should MR imaging be used?--A decision analytic approach.

PURPOSE: To determine the appropriate use of magnetic resonance (MR) imaging for preoperative staging of prostate cancer. MATERIALS AND METHODS: Literature review was performed by using the principles of evidence-based medicine and medical technology assessment. A decision analytic model was used to compare (a) the strategy that radical prostatectomy is performed on the basis of clinical staging with (b) the strategy that extracapsular disease detected at MR imaging contraindicates radical prostatectomy in patients who were considered surgical candidates on the basis of clinical staging. RESULTS: After review of the literature, expert panel opinion did not recommend MR staging. No studies in which therapeutic efficacy was addressed were found. The decision analytic model indicated that the strategy including MR staging decreased costs (MR imaging, $10,568; radical prostatectomy, $11,669) and resulted in almost equal life expectancy (MR imaging, 12.59 years; radical prostatectomy, 12.60 years) and quality-adjusted life-years ([QALYs] MR imaging, 12.53; radical prostatectomy, 12.52). Results of sensitivity analyses demonstrated that the MR strategy was both more effective and less costly if the prior probability of extracapsular disease was at least 39% when considering QALY and 50% when considering unadjusted life expectancy. CONCLUSION: It is not yet conclusively determined whether preoperative MR staging is appropriate, but results of decision analysis suggest that MR staging is cost-effective for men with moderate or high prior probability of extracapsular disease.

Contraindications↗
PubMed2000

Accuracy of normal-dose contrast-enhanced MR angiography in assessing renal artery stenosis and accessory renal arteries.

OBJECTIVE: The purpose of this study was to evaluate the accuracy of breath-hold contrast-enhanced MR angiography in the assessment of renal artery stenosis and accessory renal arteries using a standard dose of gadolinium. SUBJECTS AND METHODS: Thirty-eight patients suspected of having renal artery stenosis underwent MR angiography and intraarterial digital subtraction angiography, which was the method of reference. Three-dimensional gradient-echo MR subtraction angiography (TR/TE, 5.8/1.8 msec) was performed on a 1.5-T imager using a phased array body coil. Before imaging, a separate timing bolus sequence was used, administering 1.0 ml of contrast agent. Gadopentetate dimeglumine (15 ml) was injected using an MR power injector. Two observers, who were unaware of each other's interpretation and of MR findings, assessed digital subtraction angiography. Likewise, two other observers assessed MR angiography. RESULTS: Digital subtraction angiography depicted 75 main and 17 accessory renal arteries (n = 92). All main renal arteries and 13 accessory renal arteries were identified on MR angiography. Compared with digital subtraction angiography, MR imaging correctly classified 57 of 66 arteries without a hemodynamically significant stenosis (0-49%), 22 of 22 arteries as significantly stenotic (50-99%), and four of four occluded arteries; five stenoses were overestimated. There was one false-positive finding of an accessory renal artery on MR angiography that was identified retrospectively on digital subtraction angiography. Interobserver agreement was high. Sensitivity and specificity for grading significant stenosis were 100% and 85%, respectively. CONCLUSION: Contrast-enhanced MR angiography, using +/-0.1 mmol/kg of gadolinium, is an accurate method in the assessment of renal artery stenosis and accessory renal arteries.

Adolescent↗