PubMed Health⌕ Search

Biomedical subjects

G J Jager

Publications and source records attributed to G J Jager.

At least 19 recordsLinked to original sources
PubMed2004

Accuracy of rigid CT-FDG-PET image registration of the liver.

Diagnostic and surgical strategies could benefit from accurate localization of liver malignancies via CT-FDG-PET image registration. However, registration uncertainty occurs due to protocol differences in data-acquisition, the limited spatial resolution of positron emission tomography (PET) and the low uptake of 18F-fluorodeoxyglucose (FDG) in normal liver tissue. To assess this uncertainty, methods were presented to estimate registration precision and systematic bias. A semi-automatic, organ-focused method was investigated to minimize the uncertainty well beyond the typical uncertainty of 5-10 mm obtained by commonly available methods. By restricting registration to the liver region and by isolating the liver on computed tomography (CT) from surrounding structures using a thresholding technique, registration was achieved using the mutual information-based method as implemented in insight toolkit (ITK). CT and FDG-PET images of 10 patients with liver metastases were registered rigidly a number of times. Results of the organ-focused method were compared to results of three commonly available methods (a manual, a landmark-based and a 'standard' mutual information-based method) where no dedicated image processing was performed. The proposed method outperformed the other methods with a precision (mean+/-s.d.) of 2.5+/-1.3 mm and a bias of 1.9 mm with a 95% CI of [1.0, 2.8] mm. Unlike the commonly available methods, our approach allows for robust CT-FDG-PET registration of the liver, with an accuracy better than the spatial resolution of the PET scanner that was used.

Fluorodeoxyglucose F18↗
PubMed2002

Efficacy of fluorine-18-deoxyglucose positron emission tomography in detecting tumor recurrence after local ablative therapy for liver metastases: a prospective study.

PURPOSE: The aims of this prospective study were to investigate the potential role of fluorine-18-deoxyglucose (FDG) positron emission tomography (PET) in determining the efficacy of the local tumor ablative process and to determine the added value of FDG-PET in the detection of tumor recurrence during follow-up. PATIENTS AND METHODS: Twenty-three patients with unresectable colorectal liver metastases were followed up after local ablative therapy consisting of a standard protocol including FDG-PET scanning, computed tomography (CT) scanning, and carcinoembryonic antigen measurements. The mean follow-up period was 16 months (range, 10 to 21 months). RESULTS: Ninety-six lesions was treated, 56 by local ablative treatment. Within 3 weeks after local ablative treatment, 51 lesions became photopenic on FDG-PET, while five lesions (in five patients) showed persistent activity on FDG-PET. In four of five FDG-PET-positive lesions, a local recurrence developed during follow-up; one FDG-PET-positive lesion turned out to be an abscess. None of the FDG-PET-negative lesions developed a local recurrence during a mean follow-up period of 16 months. During follow-up, 11 patients showed recurrence in the liver outside of the treated area. In all cases, previously negative FDG-PET scans became positive. Extrahepatic recurrence was encountered in nine patients during follow-up; FDG-PET showed all nine cases of tumor recurrence. There was one false-positive FDG-PET caused by an intra-abdominal abscess. In all patients, the time point of detection of recurrence by FDG-PET was considerably earlier than the detection by CT. CONCLUSION: FDG-PET seems to have a significant impact in measuring treatment efficacy directly after local ablative therapy. Furthermore, FDG-PET has an added value in patient follow-up because it reveals recurrences earlier than conventional diagnostic modalities.

Aged↗
PubMed2002

Value of positron emission tomography with [F-18]fluorodeoxyglucose in patients with colorectal liver metastases: a prospective study.

PURPOSE: To assess prospectively the value of fluor-18-deoxyglucose (FDG) positron emission tomography (PET), in addition to conventional diagnostic methods (CDM), as a staging modality in candidates for resection of colorectal liver metastases. PATIENTS AND METHODS: In 51 patients analyzed for resection of colorectal liver metastases, clinical management decisions were recorded after a complete work-up with CDM. Afterward, FDG-PET scans were performed and any change of clinical management according to FDG-PET results was carefully documented. Discordances between FDG-PET and CDM results were identified and related to the final diagnosis by histopathology, intraoperative findings, and follow-up. RESULTS: In 10 (20%) out of 51 patients, clinical management decisions based on CDM were changed after FDG-PET findings were known. FDG-PET detected unresectable pulmonary (n = 5) and hepatic metastases (n = 1) and ruled out extrahepatic (n = 2) and hepatic disease (n = 2). Due to FDG-PET, eight patients were spared unwarranted liver resection or laparotomy and two other patients were identified as candidates for liver resection. When the results of FDG-PET were regarded as decisive in a retrospective analysis, potential change of management was 29% (15 patients). FDG-PET and CDM showed discordant extrahepatic results in 11 patients (22%) and discordant hepatic results in eight patients (16%). Compared with CDM, FDG-PET resulted in true upstaging (n = 11), true downstaging (n = 5), false upstaging (n = 1), and false downstaging (n = 2). The detection rate of liver metastases on a lesion basis was generally better for computed tomography than for FDG-PET (80% v 65%); this was related to tumor size. CONCLUSION: FDG-PET as a complementary staging method improves the therapeutic management of patients with colorectal liver metastases, especially by detecting unsuspected extrahepatic disease.

Adult↗
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

Long-term results of treating hepatic colorectal metastases with cryosurgery.

BACKGROUND: The purpose of this study was to determine the long-term efficacy of cryosurgery as an adjunct to hepatic resection in patients with colorectal liver metastases not amenable to resection alone. METHODS: Thirty patients met the following inclusion criteria: metastases confined to the liver and judged irresectable, ten or fewer metastases, cryosurgery alone or in combination with hepatic resection allowed tumour clearance. RESULTS: Median follow-up was 26 (range 9--73) months. Overall 1- and 2-year survival rates were 76 and 61 per cent respectively. Median survival was 32 months. Disease-free survival at 1 year was 35 per cent, at 2 years 7 per cent. Six patients developed recurrence at the site of cryosurgery; given that the total number of cryosurgery-treated lesions was 69 the local recurrence rate was 9 per cent. CONCLUSION: In patients with colorectal liver metastases, local ablative techniques can be used as an effective adjunct to hepatic resection to obtain tumour clearance.

Aged↗
PubMed2001

Patient selection for magnetic resonance imaging of prostate cancer.

BACKGROUND: Routine magnetic resonance (MR) imaging for local staging of prostate cancer is controversial, due to moderate staging performance. However, MR imaging may be beneficial in a subgroup of patients with clinically localized prostate cancer. OBJECTIVE: To define the patient group in which local staging of prostate cancer using MR imaging is useful for treatment outcome. METHODS: We used a decision analytic model based on data found in the literature to define the patient subgroup which may benefit from local staging with MR imaging. We applied the threshold approach to calculate the threshold where direct surgery and surgery after MR imaging (surgery-MR imaging threshold) result in equal utility. Additionally, we calculated the threshold where direct radiation and radiation after MR imaging (MR imaging-radiotherapy threshold) result in equal utility. RESULTS: We found that the surgery-MR imaging threshold was at a probability of 45% of having stage > or =T(3) disease. The MR imaging-radiotherapy threshold was at a prior probability of 81% of having stage > or =T(3) disease. CONCLUSIONS: The application of the threshold approach indicated that MR imaging should be limited to patients with an intermediate-high risk of having stage T(3) disease.

Aged↗
PubMed2001

High prevalence of testicular adrenal rest tumors, impaired spermatogenesis, and Leydig cell failure in adolescent and adult males with congenital adrenal hyperplasia.

In male patients with congenital adrenal hyperplasia, testicular tumors, or so-called adrenal rest tumors, have been described, but their presence in well controlled patients is thought to be rare. In this study, the prevalence of testicular tumors in 17 adolescent and adult male patients with congenital adrenal hyperplasia (age, 16-40 yr) was investigated. In 16 of 17 patients, one or more testicular tumors, ranging in maximal length from 0.2-4.0 cm, were found on ultrasonography. In 6 patients, the testicular tumors were palpable. Undertreatment, defined as the presence of a salivary androstenedione level (mean of 6 saliva samples collected over 24 h with intervals of 4 h) above the upper reference morning level, was found in 5 of 17 patients at the time of investigation. The other 12 patients were treated adequately or even over treated at the time of investigation. Nevertheless, 11 of these 12 patients showed testicular tumors on ultrasonography. Neither the presence of undertreatment at the time of investigation nor characteristics of the therapeutic regimen (daily dose of hydrocortisone equivalents per body surface, the use of glucocorticoid medication either two or three times a day, or the time of taking the highest glucocorticoid dose either in the morning or the evening) could predict tumor size (maximal diameter of largest tumor). In patients who were heterozygous or homozygous for the deletion or conversion of the CYP21 gene, tumor size was significantly larger than in patients who did not have this genotype. Impairment of Leydig cell function as manifested by decreased plasma levels of T was found in 6 of 17 patients. Semen analysis in 11 patients revealed azoospermia in 3 patients and poor semen quality in 4 patients. We conclude that, when carefully sought for, testicular adrenal rest tumors are frequently present in adolescent and adult males with congenital adrenal hyperplasia and are often accompanied by impaired spermatogenesis and Leydig cell failure.

17-alpha-Hydroxyprogesterone↗
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↗
PubMed1999

Fast dynamic gadolinium-enhanced MR imaging of urinary bladder and prostate cancer.

Among the noninvasive imaging modalities, contrast enhanced magnetic resonance (MR) imaging is the most powerful tool with which to visualize vascularity. Common pathology only shows microvessel density, whereas dynamic MR imaging is sensitive to the total endothelial surface area of perfused vessels. Therefore, dynamic MR imaging may be of additional value in tumor staging and in evaluating therapies that affect the perfused microvessel density or surface area, such as chemo-, radiation, or anti-angiogenic therapy. In urinary bladder cancer, this technique results in improved local and nodal staging, in improved separation of transurethral granulation tissue and edema from malignant tumor, and in improved evaluation of the effect of chemotherapy. In prostate cancer, dynamic MR imaging may be of help in problematic cases. This technique can assist in determining seminal vesicle infiltration, in depicting of minimal capsular penetration, and in recognizing tumors within the transitional zone. Also, based on very rapid enhancement, very poorly differentiated tumors can be recognized. Evaluation of the effects of therapy is another promising area, however a lot of research remain to be done. This article reviews some basics of fast enhancement techniques, provides practical information, and shows recent developments, in using these fast techniques for staging and grading of bladder and prostate cancer, and for evaluating the effect of therapy.

Contrast Media↗
PubMed1999

Human prostate: multisection proton MR spectroscopic imaging with a single spin-echo sequence--preliminary experience.

The authors investigated the feasibility of a multisection proton magnetic resonance (MR) spectroscopic imaging technique for the acquisition of metabolic information in the human prostate. Multisection MR spectroscopic imaging was performed of a citrate phantom and of the prostates of eight adult volunteers. High-quality proton MR spectra and citrate metabolite maps of the prostate were obtained with this method.

Adult↗
PubMed1998

[A role for cryosurgery in the treatment of non-resectable liver metastases of colorectal neoplasms].

Liver metastases occur in over 40% of patients with colorectal carcinomas. The best prospect of cure is achieved by resection of the metastases. However, only 10-15% of the patients with hepatic metastases are estimated to be candidates for resection. When curative resection cannot be performed the options for treatment are limited. Response rates to chemotherapy are around 40% and even then survival benefit is generally limited to a few months. Hepatic cryosurgery recently provided a new therapeutic approach for unresectable liver metastases. For cryosurgery tumour tissue is located by ultrasonography and then cooled by liquid nitrogen to a temperature of -196 degrees C, which results in necrosis of tumour tissue. In a limited number of series encouraging results of cryosurgery have been reported. One year and two year survival rates of respectively 70% and 50% were reported after cryosurgery for hepatic metastases. Disease free survival rate after 2 years varies from 20% to 28%. If recurrence of the disease occurred in the liver it was generally outside the areas treated by cryosurgery. Benefit in survival is only achieved when all tumour tissue is treated adequately. Hepatic cryosurgery is appropriate in those patients with unresectable metastatic disease in whom cryosurgery alone or in combination with resection is able to eradicate all metastatic disease in the liver.

Antineoplastic Agents↗
PubMed1998

Meniscal cysts: detection with high-resolution sonography.

OBJECTIVE: The purpose of this study was to determine the feasibility of high-resolution sonography for the detection of meniscal cysts and associated meniscal tears and for the differentiation of meniscal cysts from other masses at the knee joint. SUBJECTS AND METHODS: Fifty consecutive patients (51 knees) with a palpable mass at the knee joint were examined prospectively using a 7.5-MHz annular array transducer. Mass consistency and location and meniscal integrity were evaluated. Sonographic findings were correlated with surgery (46/51) and histopathology (15/51). Five patients did not undergo surgery. RESULTS: At surgery, 32 masses appeared to be meniscal cysts, whereas 19 were other types of masses. Sonographically, 31 of the 32 meniscal cysts were diagnosed correctly. Sonographic differentiation of the other types of masses from meniscal cysts could reliably be made in 17 of 19 cases; two masses were falsely interpreted as meniscal cysts. Sensitivity, specificity, and accuracy of sonography in the depiction of meniscal cysts were 97%, 86%, and 94%, respectively. The positive predictive value was 94% and the negative predictive value was 92%. Meniscal tears (31/46) and meniscal tears concomitant with meniscal cysts (26/32) were detected with an accuracy of 83% and 88%, respectively. CONCLUSION: Sonography is an accurate imaging technique for the detection of meniscal cysts and associated meniscal tears. Differentiation of meniscal cysts from other cystic and solid masses at the knee joint can be reliably made with sonography.

Adolescent↗