Biomedical subjects

S H Ruijs

Publications and source records attributed to S H Ruijs.

At least 19 recordsLinked to original sources

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

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↗

PubMed1998

Evaluation of chemotherapy in advanced urinary bladder cancer with fast dynamic contrast-enhanced MR imaging.

PURPOSE: To evaluate if the failure of chemotherapy in patients with advanced urinary bladder cancer can be predicted early in the course of chemotherapy with fast dynamic contrast material-enhanced magnetic resonance (MR) imaging. MATERIALS AND METHODS: In this prospective study, 22 consecutive patients with histologically proved advanced urinary bladder cancer underwent MR imaging before and after two, four, and six cycles of chemotherapy with methotrexate, vinblastine, adriamycin, and cisplatin (MVAC). The response after two chemotherapy cycles was evaluated by using conventional tumor size parameters at unenhanced MR imaging and with changes in the time to the start of tumor or lymph node enhancement at fast dynamic contrast-enhanced MR imaging. The results obtained with these techniques were compared with the findings at histopathology in cystectomy (n = 9) or multiple transurethral resection (n = 13) specimens obtained after completion of chemotherapy. RESULTS: After two MVAC cycles, the accuracy, sensitivity, and specificity in distinguishing responders from nonresponders with conventional MR imaging were 73%, 79%, and 63%, respectively. With the dynamic technique, these were 95%, 93%, and 100%, respectively. Although the differences between these values are not significant (P = .48 for sensitivity, .25 for specificity, and .07 for accuracy), the data indicate that dynamic enhanced MR imaging performed better than unenhanced MR imaging. Dynamic imaging yielded correct results after two MVAC cycles in 21 cases, and in all cases after four cycles. After four MVAC cycles, the accuracy of dynamic MR imaging was significantly better (P < .05). Persisting early enhancement after four MVAC cycles correctly corresponded with lack of response in all nine cases, and after two cycles in eight of these cases. The unenhanced MR technique showed initial tumor size reduction in three of these cases. CONCLUSION: Conventional and dynamic enhanced MR imaging were used to evaluate chemotherapy after two, four, and six cycles of MVAC in 22 patients with bladder cancer. After two cycles, dynamic MR imaging helped detect 13 of 14 responders and eight of eight nonresponders. It helped detect five of seven lymph node responders and two of two nonresponders. Thus, it may be possible to predict after two MVAC cycles whether a patient will respond to chemotherapy.

Adult↗

PubMed1997

Proton MR spectroscopy of the normal human prostate with an endorectal coil and a double spin-echo pulse sequence.

This report describes the use of an endorectal coil and a double spin-echo pulse sequence for localized 1H MR spectroscopy of the normal prostate in volunteers. The spectra showed well-resolved signals for citrate, (phospho)choline, and creatine protons. Additional signals were assigned to taurine and myoinositol protons. J modulation of the main and outer peaks of citrate could be monitored in vivo. Apparent relaxation times T1 and T2 have been estimated for the methyl protons of cholines and creatine. An effective T1 relaxation time was estimated for the main peaks of the citrate multiplet. Ratios of the integrals of these resonances have been evaluated, and tissue contents of choline and creatine were estimated using the H2O signal as an internal reference. Spectroscopic imaging experiments revealed a lower relative citrate signal in central parts of the prostate than in peripheral parts.

Adult↗

PubMed1997

Mammographic changes in postmenopausal women on hormonal replacement therapy.

The purpose of this study was to investigate the extent of the effects of hormonal replacement therapy (HRT) on the mammographic breast pattern in postmenopausal women. In a hospital-based study mammographic examinations of 81 postmenopausal women were evaluated retrospectively, before and after 1-2 years of treatment with oestrogens or a combination of oestrogens and progestagens. Each individual mammographic film was examined separately, and the glandular tissue was classified according to a modified Wolfe classification. In a screening-centre-based study two consecutive mammograms, with a 2-year interval, of 645 women, of whom 70 were using some kind of hormone therapy, were evaluated retrospectively. In the hospital-based study 31 % of patients treated with combination HRT showed an increase in fibroglandular tissue compared with only 8.7 % in the group treated with oestrogens alone. The difference was statistically significant (p = 0.046). In the screening-based study 14.3 % of the women using hormonal therapy showed an increase, whereas in the non-users no increase was found (p = 1.24 x 10(-10)). After beginning HRT many women (between 14 and 25 % in our experience) can be expected to undergo a mammographically detectable increase in fibroglandular tissue. Radiologists should be aware of the aetiology of such changes, and can obtain information on HRT most conveniently by having the technologist routinely question each patient.

Aged↗

PubMed1997

Dynamic TurboFLASH subtraction technique for contrast-enhanced MR imaging of the prostate: correlation with histopathologic results.

PURPOSE: To assess whether a TurboFLASH (fast low-angle shot) magnetic resonance (MR) sequence can improve the accuracy of fast spin-echo (SE) endorectal coil MR imaging in the staging and localization of prostate cancer. MATERIALS AND METHODS: In 57 patients with prostate cancer, MR imaging was performed with the following sequences: T1-weighted SE, T2-weighted fast SE, single-section gadolinium-enhanced dynamic subtracted TurboFLASH (one image every 1.25 or 2.5 seconds), and late-phase gadolinium-enhanced T1-weighted SE. Retrospectively, two blinded independent readers graded onset and steepest slope of enhancement and assessed tumor involvement and capsular penetration. MR findings were correlated with histopathologic results. RESULTS: On TurboFLASH images, prostate cancer was characterized by early and rapidly accelerating enhancement compared with that of surrounding tissues. Average sensitivity, specificity, and accuracy for detection of tumor involvement for the two readers with TurboFLASH images were 73.5%, 81.0%, and 77.5%. These values with fast SE images were 57.5%, 80.5%, and 72.0%. Depiction of capsular penetration and delineation and staging of tumor were better when TurboFLASH images were included with fast SE images. Differences between the two sequences, however, were not statistically significant. CONCLUSION: Because the TurboFLASH sequence did not statistically significantly improve tumor localization and staging results, routine use is not recommended. The technique may be useful for selected patients with equivocal evidence of capsular penetration.

Aged↗

PubMed1996

Staging urinary bladder cancer after transurethral biopsy: value of fast dynamic contrast-enhanced MR imaging.

PURPOSE: To evaluate contrast enhancement patterns of urinary bladder cancer and surrounding structures and to evaluate a fast dynamic first-pass magnetic resonance (MR) imaging technique in tumor and node staging and in differentiation of urinary bladder cancer from postbiopsy effects. MATERIALS AND METHODS: Sixty-one consecutive patients with histologically proved urinary bladder cancer were referred to undergo unenhanced and dynamic MR imaging 1-4 weeks after transurethral resection or biopsy. Subtraction and time (to beginning of enhancement) images were acquired. RESULTS: Results with unenhanced T1- and T2-weighted images were compared with those obtained with the unenhanced images plus dynamic contrast material-enhanced single-section turbo fast low-angle shot (FLASH) images. Urinary bladder cancer started to enhance 6.5 seconds +/- 3.5 (standard deviation) after the beginning of arterial enhancement, which was 4 seconds earlier than most other structures (postbiopsy tissue, 13.6 seconds +/- 4.2). In differentiation of postbiopsy tissue from malignancy on the basis of the beginning of enhancement depicted on time and subtracted images, accuracy improved from 79% to 90% (P < .02) and specificity improved from 33% to 92% (not significant). Overall, tumor staging accuracy improved significantly from 67% to 84% (P < .01) by adding the turbo FLASH images. CONCLUSION: Fast dynamic first-pass MR imaging, with at least one image acquired every 2 seconds, improved delineation of urinary bladder cancer, tumor staging, and detection of metastases.

Biopsy↗

PubMed1995

Guidelines for the assessment of new diagnostic tests.

RATIONALE AND OBJECTIVES: Because new diagnostic tests become available rapidly, the authors determined a need for proper assessment of tests before their implementation in clinical practice. Three factors are of pivotal importance: the selection of the proper study population, the determination of the diagnostic power including its related statistical analysis, and the relation of the new test to current diagnostic tools. Patients suspected of having a disease are those who would benefit from the application of a new test. Therefore, only those patients need be involved in the assessment study. METHODS: Summary measures of diagnostic power other than sensitivity and specificity are advocated because these conventional measures depend on cutoff points and are susceptible to selection bias. The relation between the new test and existing diagnostic tools must be established to determine if the new test contributes to the diagnostic process. RESULTS AND CONCLUSION: To avoid waste of effort and money, the authors suggest a prudent assessment approach in phases. Whereas the initial challenge consists of selection of an adequate patient population, subsequently all determinants of diseases (signs, symptoms, comorbidity, and other diagnostic factors) and factors influencing the decision to use a test (patient burden and cost) are considered.

Bayes Theorem↗

PubMed1995

Staging urinary bladder cancer: value of T1-weighted three-dimensional magnetization prepared-rapid gradient-echo and two-dimensional spin-echo sequences.

OBJECTIVE: The purpose of this study was to evaluate a magnetization prepared-rapid gradient-echo (MP-RAGE) sequence as a three-dimensional T1-weighted MR imaging technique for staging urinary bladder cancer and to compare this technique with a commonly used two-dimensional T1-weighted spin-echo sequence technique. SUBJECTS AND METHODS: For 28 consecutive patients with urinary bladder cancer, MR findings and staging results were compared with histopathologic findings after surgery or autopsy. MR imaging was performed at 1.5 T with a Helmholtz double-surface coil. Conventional T1-weighted spin-echo, three-dimensional MP-RAGE, T2-weighted spin-echo or turbo-spin-echo, and dynamic T1-weighted fast gradient-echo sequences were used. Signal difference-to-noise ratios and T1 contrast were calculated by use of operator-defined regions of interest. RESULTS: The signal difference-to-noise ratios for fluid-tumor and fat-tumor were, respectively, factors of 1.6 and 2.7 better with T1-weighted spin-echo sequences. T1 contrast of fluid-tumor was a factor of 2.6 better with three-dimensional MP-RAGE sequences, resulting in better recognition of small tumors, ascites, and dilated ureters. T1 contrast for fat-tumor was a factor of 2.0 better with T1-weighted spin-echo sequences. With the MP-RAGE sequence, motion artifacts were fewer in number than those noted with the T1-weighted spin-echo sequence, and susceptibility artifacts were equal in number to those noted with the T1-weighted spin-echo sequence. Using the three-dimensional technique, we performed off-line reconstruction of 1- to 2-mm high-resolution images in every desired plane. Because of higher spatial resolution, the availability of multiplanar reconstructions, and better fluid-tumor contrast and despite lower signal difference-to-noise ratios, three-dimensional MP-RAGE images resulted in better recognition of local tumor extension (n = 11), adhesions and bowel wall invasion (n = 5), lymph node metastases (n = 2), and bone marrow metastases (n = 2). The staging accuracy for the combination of three-dimensional MP-RAGE, T2-weighted, and dynamic sequences was 93%; that for the combination of two-dimensional T1-weighted spin-echo, T2-weighted, and dynamic sequences was 78%. Nodal staging was also more accurate with MP-RAGE sequences (accuracy of 93% vs 86% for T1-weighted spin-echo sequences). CONCLUSION: Compared with two-dimensional T1-weighted spin-echo imaging, three-dimensional MP-RAGE imaging resulted in a 15% improvement in staging. Our findings suggest that optimal staging of urinary bladder carcinoma requires three-dimensional imaging techniques.

Adult↗

PubMed1994

Magnetic resonance imaging for volume estimation of large multinodular goitres: a comparison with scintigraphy.

As a result of increasing interest in non-surgical treatment for the reduction of goitre size the use of magnetic resonance (MR) imaging for volume estimation of large multinodular goitres was evaluated in 20 patients (three males and 17 females; age 61 +/- 21 years) with a multinodular goitre larger than 100 ml. In addition, MR measurements were compared with scintigraphic (SC) volume estimations. Intraobserver coefficient of variation (CV) of MR measurements was 2.2 +/- 2.0% (Observer 1) and interobserver CV 4.1 +/- 2.2% (Observers 1 and 2). In all 20 patients signs of mechanical complications were shown on MR images. For SC measurements intraobserver CV was 7.5 +/- 5.7% (Observer 3) and 5.4 +/- 5.1% (Observer 4). Interobserver CV was 10.1 +/- 6.1%. The correlation between measurements with both methods was not strong (r = 0.665) and the resulting CV was 17.3 +/- 14.2%. Underestimation of SC volumes could not be explained by the presence of cysts on the surface of the thyroid. It is concluded that MR imaging can be used for in vivo thyroid volume estimation in large multinodular goitres. The high precision of MR measurements makes this technique potentially useful for the evaluation of thyroid growth and non-surgical treatment for reducing goitre size. Scintigraphic volume measurements do not suffice for this purpose. An additional advantage of MR imaging is the detailed anatomical information it provides with regard to mechanical complications of large goitres.

Adult↗

PubMed1994

Diagnosis of hypertrophic pyloric stenosis: value of sonography when used in conjunction with clinical findings and laboratory data.

OBJECTIVE: This study aimed to determine the value of sonography in the diagnosis of hypertrophic pyloric stenosis in patients with no palpable olive-shaped mass. MATERIALS AND METHODS: One hundred and five children with projectile vomiting but no palpable mass had sonography because of possible hypertrophic pyloric stenosis. The patients' history, signs and symptoms, and results of laboratory tests were incorporated into the statistical analysis. Using medical history, signs and symptoms, and laboratory results in one case and history, signs and symptoms, laboratory results, and pyloric measurements based on sonographic findings in another case, we composed the best predicting logistic regression models. RESULTS: The ability to predict hypertrophic pyloric stenosis is greatly increased by adding information obtained from sonography. At 91% specificity of the final model, only 5% of the patients with no evidence of the abnormality actually had hypertrophic pyloric stenosis. The positive predictive value is thus 94%, and the negative predictive value is 95%. CONCLUSION: The results justify the use of sonography as the diagnostic procedure of choice for infants suspected of having hypertrophic pyloric stenosis.

Female↗

PubMed1993

Differential effects of glucocorticoids on cortical appendicular and cortical vertebral bone mineral content.

The susceptibility to glucocorticoid-induced bone loss may vary in different parts of the skeleton. We studied 62 patients with rheumatoid arthritis, 26 of whom were on low-dose glucocorticoid treatment. Bone mineral content (BMC) in the forearm was measured by single photon absorptiometry at a cortical, diaphyseal, and at a mixed cortical and trabecular, metaphyseal site. Lumbar BMC was measured by dual energy computed tomography in a trabecular and a cortical region of interest. The presence of vertebral deformities was evaluated on lateral spine radiographs. After correction for possibly confounding variables, prednisone therapy significantly influenced BMC at both the trabecular (-22.0%, 95% confidence interval -36.0% to -8.1%) and cortical (-24.8%, 95% confidence interval -39.3% to -10.3%) lumbar site. A significant effect was also seen at the metaphyseal (-15.7%, 95% confidence interval -27.1% to -4.2%), but not the diaphyseal (-3.9%, 95% confidence interval -14.1% to 6.4%) site in the forearm. Correlations between peripheral and vertebral BMC were moderate at best. The diaphyseal to metaphyseal BMC ratio did not identify patients with vertebral osteoporosis. It is concluded that the anterior cortical rim of the vertebral body is more susceptible to the effects of glucocorticoids than the cortical bone in the forearm, and that measurements of trabecular and anterior cortical vertebral BMC are essential in the management of patients with possible glucocorticoid-associated osteoporosis.

Absorptiometry, Photon↗

PubMed1993

The role of MR imaging in carcinoma of the urinary bladder.

In this article, the role of MR imaging in the management of carcinoma of the urinary bladder is reviewed and illustrated. The appearance of the normal urinary bladder and of bladder carcinoma on MR images is shown. Important factors for optimal MR imaging of urinary bladder carcinoma are reviewed. New developments such as three-dimensional and fast spin-echo sequences and the use of contrast agents, endorectal imaging, and phased array coils are discussed. Finally, the value of MR imaging in the staging of bladder carcinoma is described, and MR staging is compared with clinical staging, staging based on findings from intravesical sonography, and CT staging.

Artifacts↗

PubMed1993

Magnetic resonance imaging of urinary bladder cancer: an overview and new developments.

The role of magnetic resonance (MR) imaging in the management of carcinoma of the urinary bladder is reviewed and illustrated. In vivo and in vitro MR images of the normal urinary bladder, carcinoma, and surrounding structures are presented. Factors for optimal MR imaging of urinary bladder carcinoma are reviewed. Pulse sequence optimization, (endorectal) surface coils, and other new developments such as fast spin echo, subtraction turbo-fast low angle shot (FLASH), three-dimensional rapid acquisition gradient echo sequences, and the use of contrast agents are discussed. Finally, the value of MR imaging in staging urinary bladder carcinoma is compared with clinical staging, staging based on findings from computed tomography and intravesical sonography.

Humans↗

PubMed1992

A view from the Nijmegen PACS project.

A view on PACS is given from a radiology department involved in PACS as part of its medical research environment. Special attention is payed to historical developments in medical imaging to study the context of actual PACS developments. Some directions of future diagnostic developments are indicated. Both image data-acquisition and presentation techniques are of interest to medical as well as industrial applications. It is pointed out how PACS is thought to depend on contextual factors.

Diagnostic Imaging↗

PubMed1992

Vertebral osteoporosis in rheumatoid arthritis patients: effect of low dose prednisone therapy.

The effect of low dose prednisone therapy on spinal bone mass is controversial. We measured lumbar trabecular and cortical bone mineral density (BMD) in 74 rheumatoid arthritis (RA) patients by dual energy quantitative computerized tomography in a cross-sectional study. The presence of vertebral deformities was evaluated on a lateral spine radiograph. Patients who had never been treated with corticosteroids (n = 44) were compared with patients on long-term low dose (less than or equal to 10 mg/day) prednisone therapy (n = 30). After correction for confounding variables the lumbar BMD was highly significantly influenced by prednisone therapy in postmenopausal patients (estimated influence -31.2% on trabecular BMD and -37.2% on cortical BMD). Vertebral deformities were also significantly more frequent in prednisone treated postmenopausal patients. No negative effect of prednisone treatment could be demonstrated in male patients. In contradiction to previous reports we conclude that long-term prednisone therapy may be associated with development of spinal osteoporosis in postmenopausal RA patients, even when low doses are used.

Arthritis, Rheumatoid↗

PubMed1992

Single- versus dual-energy quantitative computed tomography for spinal densitometry in patients with rheumatoid arthritis.

Lumbar bone mineral density was measured by both single- and dual-energy quantitative computed tomography in 109 patients with rheumatoid arthritis. The results were corrected for the age-related increase in vertebral fat content by converting them to percentages of expected densities, using sex and energy-level specific regression equations obtained in a normal reference population. The percentages of expected density are approximately 10% lower in the single- than in the dual-energy mode, both in the patients with and without prednisone therapy. This difference is statistically highly significant, and is positively correlated with the duration of the disease and with the degree of radiological joint destruction. The data suggest that the vertebral fat content may be increased in patients with rheumatoid arthritis, as a consequence of disease-dependent mechanisms.

Adipose Tissue↗

PubMed1989

The value of intravesical echography combined with double-surface coil magnetic resonance imaging in staging bladder cancer.

Correct staging of bladder tumours is essential for planning the best therapeutic strategy and is therefore directly related to the prognosis. In this study of 15 patients with bladder cancer, a new method using magnetic resonance imaging (MRI) with a newly developed double-surface coil was tested for bladder cancer staging and compared with other existing techniques. Ultrasonography produced 2 cases of overstaging and 2 of understaging. This was due to the inability of this method to evaluate muscular infiltration accurately. All superficial bladder tumours were staged correctly with ultrasound with the exception of 1 case that was overstaged because of superficial tumour calcification. Double-surface coil MRI correctly staged all infiltrating tumours. Two small superficial tumours were missed by MRI, while another superficial tumour was overstaged. It is suggested that double-surface coil MRI and intravesical ultrasonography are good complementary examinations in the pre-operative staging of bladder tumours. Larger studies are necessary to prove the reliability of this conclusion.

Adult↗